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FACULTY OF CIVIL ENGINEERING
Eng. DORIN AŞCHILEAN
ABSTRACT
The Thesis
THE INFLUENCE OF THE FOUNDATION SYSTEMS ON THE QUALITY AND
EFFICIENCY OF THE CONSTRUCTIONS
The evaluation committee of the thesis :
CHAIRMAN: - Conf.dr.eng. Anca Popa – Vice Dean, Faculty of Construction, Technical
University of Cluj-Napoca;
MEMBERS: -Prof.dr.eng. Mihai Iliescu - Scientific Coordinator, Faculty of Civil
Engineering, Technical University of Cluj-Napoca;
- Prof.dr.eng. Anghel Stanciu - Reviewer, Faculty of Engineering and
Systems, Technical University "Gheorghe Asachi" of Iasi;
- Prof.dr.eng. Marin Marin - Specialist, Department of Construction,
Polytechnic University of Timisoara.
- Prof.dr.eng. Augustin Popa - Referee, Faculty of Engineering, Technical
University of Cluj-Napoca;
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ABSTRACT
The Thesis
The following PhD thesis is structured into 6 chapters. It contains 203 pages and it is
sustained by a bibliography of 137 references.
The purpose of the thesis is to analyze the influence of the foundation systems on the
quality and efficiency of the constructions, both in terms of global domain knowledge and
through the experience acquired by developing a large number of reference works.
Although the diversity of the foundation execution technologies increases the difficulty of
designing foundation systems, the detailed study presented in the thesis will help at outlining
technical and economic considerations regarding the choice of foundation systems, especially on
improved ground.
Moreover, the applicability of the ELECTRE 1 multicriterial analysis method, allows the
most efficient choosing, of several possible options, of the foundation execution technology.
Chapter 1 – General considerations
1.1. The need of constructions
People have carried out various constructions since prehistoric times and the execution
technology has been improved over time.
The first buildings made by the people, were simple huts, tents and shelters, and the first
bridges were probably wooden logs placed across rivers.
The most famous buildings of the antiquity are the seven wonders of the world,
representing tokens of those times. The oldest known version, of the list, belongs to Antipater of
Sidon and was developed in the IInd century BC. This list seems to be based on popular Greek
travel guides and includes only buildings around the Mediterranean.
1.2. The evolution of the constructions in Romania
During the Roman domination, on this country’s territory a first network of roads, with
stability and quality value, has been built. Its goal was linking this new province through roads
similar to the ones that were built in the entire the Roman Empire.
The "Trajan's Bridge", built by Apollodorus of Damascus, dating from the Roman
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occupation times and it is the oldest known bridge in Dacia, while the first bridge crossing the
Danube and also, one of the great buildings of the Roman Empire.
Until the application of the Organic Regulation in the Romanian Country, in 1831 and in
1832 in Moldova, it cannot be talked about a concern on the servicing or the construction of roads
in United Principalities. The Organic Regulation has appended the building of paved roads with
cross slopes.
In 1870 the cubic stone paving of the streets has began in Bucharest and in 1872, the first
tests on natural asphalt paving compaction for the roadway have been carried out. In the same
period of time, the execution of wooden pavements has been allowed for some of the streets of
Bucharest.
After the great financial crisis, from the beginning of the last century, engineers have tried
to use as few materials brought from abroad as possible, and thus reinforced concrete bridges
have been developed; first smaller and then increasingly larger.
The year 1903 was the moment when the reinforced concrete has began to be widely used;
the year when the Directorate of Service for Bridges and Highways has began to design and
execute concrete bridges. The first bridges had been built on the Pitesti - Curtea de Arges road,
with an opening of 5 m, and the one near Piatra - Neamt, with an opening of 6 m.
The variety of solutions that are required to the execution of the foundations, depending
on the nature of the soil, the different sizes of the loads, and their action mode, etc. are generally
making the typification of the foundation solutions to be laborious, thereby contributing to
increasing the duration of execution of the cycle 0, the boosting of the cost and to lower
productivity.
1.3. A “modest" history of the foundation systems’ development
The history of the foundation systems’ development is strictly related to the beginning of
the technology and of the art of building. It has been a long, arduous road, strewn through
millenniums with some buildings that, although carried out empirically, have resisted so far,
defying time.
Wood, natural stone, brick, lime mortar, concrete, reinforced concrete and even metal, are
ones of the building materials that have been used over time.
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The first foundation systems have appeared before almost five thousand years ago, at the
building of the pyramids. Most of them have the base (foundation) made of stone blocks, with
racks inclined inwards and resting on layers of limestone in the base layer, Fig. 1.7.
Fig. 1.7. Foundation of the pyramid
It can be said that we are at the first direct foundation solution on a difficult foundation
terrain (loose / medium). Creating a foundation on the base perimeter could be considered to be
an avant-garde solution, as it is a precursor of the foundation solutions that use this system of foot
contour "skirt", in order to eliminate the plasticization phenomena.
An examination of the Meidum pyramid, the only one that suffered structural damage,
showed that the foundation blocks rested directly on the desert sand, instead of leaning beneath it,
whereas the other pyramids rested on rock, and the foundation blocks are arranged with
horizontal joints not inclined towards the inside Fig. 1.8.
Fig. 1.8. The Pyramid of Meidum foundation
However, the system was not effective for areas with seismic, horizontal arrangement,
because the joints favoured the slip and fall of the blocks located on the faces of the pyramid.
This lesson was not forgotten by Imhotep, the greatest mathematician and engineer of
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Egyptian history, who has designed the Great Pyramid of Giza. He adopted the foundation
solution of Fig. 1.7. At all of the other pyramids this foundation solution has been adopted.
Closer to us, in ancient Greece and in the Middle Ages, monumental buildings mark
important steps in construction technology, although still largely, we are in a craft stage. The
monumental constructions made in this era, though still made of stone walls, introduce the first
foundation solution on pillars of wood (1406). The roads, churches, castles, houses of this period,
mainly all used foundations made of stone walls, without any hard rock to rest on. Is the time in
which the building of the tower of Pisa (1174) has started, a construction performed on a
foundation of circular stone walls, but placed on a weak foundation soil.
During the Renaissance (XV and XVI centuries) the bases of the building foundations’
construction and of the related sciences, primary of the construction mechanics have been put.
Foundations have been developed over pillars of wood and on wooden soles.
Beside at the realisation of indirect foundation systems, wood has been used at the
building of the first weak soil consolidation solutions, in the form of wooden slats arranged at the
base of the foundation.
In our country, the implementation of systems using wood foundation appeared later, and
one of the major constructions, where this solution has been used, is the Hunyadi Castle. Later on,
the use of pillars of wood as a foundation solution can be found in Cluj, at retaining walls’
execution, in order to build the walls of the Morii channel (Romtelecom, Emil Isac, etc.).
More recently, the use of wood pillars was an effective solution to the foundation of the
Danube Ports (1884). The bays were founded on wooden pillars, with a length of 12m that were
beaten with steam drop hammers. Since the soil was poor, pilots have been passed through a
network of fascia rolls, the solution being reliable, so docks are still in operation even today.
With the replacement of stone masonry with burned brickwork, in the technique of
foundation works, the foundations began to be made of burnt clay bricks or lime mortar.
The introduction of reinforced concrete foundation work led to the first use of reinforced
concrete pillars in Romania. The first reinforced concrete pillars, in Romania, have been used in
the grain silo foundations of the Constanta harbour (then Galati and Braila). Pillars of 10-12m
have been used, which were introduced in the ground through steam pillar drivers.
Beside the direct foundation systems, indirect foundation systems (isolated, continuous,
slab), began to be introduced on improved ground. If the first solution is made by introducing
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wooden pillars, the expansion of alternatives for poor soil with good terrain, gravel, so-called
"ballast cushion”, began further.
The first works for soil improvement by adding materials have been used since 1802,
when French engineer Charles Berigny used a stiffening solution based on "Italian puzzolan" to
strengthen the platforms of Dieppe harbour.
The use of the suspension of Port soil cement was made after 1821.
In the Cluj soil, the first works of consolidation by injection was made in 1953 during the
bracing works of the Pharmacy 1 building in Liberty Square.
The execution of elastic foundations of reinforced concrete has not sought to develop
immediately the scopes of reinforced concrete. Thus, at the Hungarian Theatre of Cluj, where for
the first time in Romania to run a concrete dome (1909), the foundation solution was: concrete
blocks under each pillar of the structure.
Chapter 2 - General terms of work quality
2.1. Generalities
Throughout human history the concept of "quality" unfolded various modifications. But
whatever the historical moment, through "quality" was understood the extent to which those
interested in someone or something were satisfied by that something or someone. Thus, we speak
of the quality of a product, the quality of a person or organization, as the extent in which those
interested in them, get satisfaction in relation to them. Also, the "quality" has been integrated into
concepts related to scientific management since its appearance.
The evolution of the concept of "quality" through four stages:
- product quality – as defined in the starting times of civilization;
- quality assurance - After 1940;
- total quality - from the 1980s;
- Total quality management (TQC / TQM) - After 1990.
Since the '80s, the concept of total quality has been addressed in Europe. The objective of
this concept is successful symbiosis between quality, production and motivation, in the
performed work.
It is, moreover, the EU's economic philosophy that has and put it in practice, beginning
with the "New Approach" (1985) and the "Global Approach" (1989). This economic philosophy
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has been assumed by Romania as a basis for the accession process to the Union European,
through the full adoption of EU legislation (acquis communautaire).
JOSEPH MOSES JURAN had a significant contribution to the development of the global
quality management.
2.2. The ISO 9000 family of standards
The implementation and the continuous improvement of the EU quality system
transposition, standards, rules and technical regulations, involve simultaneously all economic
factors, public and private, each in its own sphere of responsibility. Depending on the information
received, the level of accumulated knowledge and available resources, each firm, each private
entity that plays a role in the implementation and every public authority, is directly involved in
the success / delay and / or failure, not only of the rendition of these "tools" but mainly in their
efficient use.
The European Union manner of management systems’ implementation is governed by the
"ISO 9000" quality system family.
ISO - International Organization for Standardization - is a worldwide federation of bodies
of national standards (ISO member committees). The international standards development activity
is carried out through ISO technical committees. Each committee member interested in a topic,
wherefore a technical committee has been established, has the right to be represented on that
committee. International organizations, governmental or nongovernmental, in connection with
ISO, also participate in works of this nature.
The ISO family of standards are a collection of standards that contain requirements for the
various processes carried out within the organization (such as process design, marketing,
production, service delivery, sales, supply, treatment noncompliance, etc.).
The Quality Management is a set of activities aimed at achieving certain objectives
through the optimal use of resources. This set includes the planning, coordination, organization,
and control and quality assurance.
Thus, the quality management carries out the most influence on the organization
processes, it has a direct influence in defining, documenting and the mode of application of
national rules relating to various organizational operations, a major influence on how the staff
applies those rules and not least, it guides the manner in which employees perceive and represent
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reality, and it also directs the approach on dealing with various situations arising in, or outside the
organization.
The intense competition for customers, both locally and globally, has led to a significant
increase in the importance of quality, both for products and services. Accurate identification of
consumer needs and their satisfaction before, during and after the sale (regardless of the type of
product or service features) are considered key competitive advantages. To achieve this
competitive advantage, many organizations began to be interested in implementing a quality
management system - a systematic attempt to achieve continuous improvement of product quality
and / or of the services that they provide.
Like any science, quality management is based on a series of principles that set out key
directions that an organization must follow, in order to provide maximum satisfaction to those
interested in its results.
Fig. 2.1. Quality management principles
The PDCA cycle is present in all professional grounds, in everyone's life and is used both
formally and informally, consciously or unconsciously in everything we do. Any activity, no
matter how simple or complex, follows this model.
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Fig. 2.3. PDCA Cycle
The SDCA cycles (Standardises Run-Check-Act) were generated in the modern
approaches, in addition to the PDCA cycle. While SDCA involves standardizing and stabilizing
current processes, PDCA improves them, therefore results a new SDCA cycle, Fig. 2.4.
Fig. 2.4. PDCA cycle-SDCA
The organization must operate to eliminate existing and potential causes of
nonconformities, in order to prevent their recurrence. In order to do that, organizations can use, if
necessary, corrective or preventive actions.
Quality management systems help organizations increase customer satisfaction, which is
one of the principles of quality management.
A quality system that is implemented and certified, according to the requirements of
international standards, is a real opportunity for organizations to survive in the current conditions.
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2.3. The quality management of construction works
Construction works, through their complexity and diversity, appeal for a great effort from
designers and contractors, in order for them to ensure quality work in accordance to the
requirements of technical specifications.
Although the quality legislation in Romania has been harmonized with the European
legislation, companies develop extremely laborious quality management systems, and their
effective application is done only in a reduced degree.
The alignment of requirements of the quality construction in Romania to the international
requirements has materialized trough Law. 10/1995 regarding construction quality, which has
been published in the Official Gazette no. 12 of 24 January 1995.
In 2000, the EN ISO 9001, EN ISO 9002 or EN ISO 9003 standards were combined in
standard ISO 9001 on quality management system requirements. The ISO 9001 standard was
updated in 2008 and is currently the only standard whose requirements must be met in order to
get certified.
A large construction project is always based on research. Previous results, rules,
regulations and standards, data, the experience and design of research institutes are utilized.
Given the phased implementation of the constructions, the qualitative evolution of this
activity can reveal a quality spiral, Fig. 2.5.
Fig. 2.5. The spiral of quality construction works
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Quality control must be present at all stages of execution for detailed analysis, finding
sources of materials and testing materials, marking works and the verification of the works’
compliance with the projects, etc. Laboratory test results are the base of the quality control. All
tests on materials and works are carried out by laboratories and authorized personnel according to
the inspection and testing plans.
The main phases of the design are investigating the site, making soil surveys, framing the
design and the technical specifications, drawing out the pre-estimation, obtaining necessary
permits and licenses, and finally, preparing the details of execution.
Performing work is done according to approved programs offered by the manufacturer
and the customer, generally presented starting with the bidding work stage.
The work’s acceptation is done in two stages, on completion and at the end of the
warranty period. For the acceptance on completion as required by Government Decision no. 273
of June 14, 1994, regarding the approval of the construction works’ acceptation regulation and
related facilities and rules for drawing up the technical building book, all the documents prepared
before and during construction, work quality, compliance, projects, are to be checked.
The manufacturer must restore all the work that is degraded due to failure of quality
requirements, during the warranty time-frame.
Chapter 3 – The system analysis foundation conditions - efficiency - quality
3.1. General notions about foundations
Foundations are the building blocks that are situated in contact with the good foundation
ground and are conducting to it, all the loads acting on the building.
The loads are to be distributed on the sole of the foundation as uniform as possible so that
they could be supported by the construction without repercussions on it.
In order to design and the execute the foundations, it is necessary to know the following:
- the foundation soil structure on the site of construction, both from geological and
hydro-geological point of view, the depth of the active area - the nature, thickness,
mechanical and physico-chemical properties of the layers of the soil, groundwater and
surface water, their chemical properties, aggressiveness, penetration ability in
endowments.;
- the climatic conditions – frost depth, amount of rainfall;
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- the dimensions and clearances of construction;
- the significance of the building;
- the seismicity of the region;
- the actions that are transmitted to the foundation, their nature and their most
unfavourable combinations;
- the reactions that occur on the surfaces of contact between the foundation foot and the
foundation ground;
- stress distribution on the foundation sole, loads arising in the construction elements,
that make up the foundation and the mechanical characteristics of the materials it is
made of;
- the external factors that may affect the foundation stability by changing the
characteristics of the foundation soil or by giving birth to additional forces.
Depending on the depth whereat the good foundation ground can be found, foundations
can be classified in:
- Direct foundations, foundations called surface or shallow foundations:
o rigid foundations, made of natural stone, concrete or cyclopean concrete;
o elastic foundations, made of reinforced concrete;
o foundations for road structures.
- indirect or deep foundations, made in order to transmit the loads of the construction
to the layer of foundation situated at depth (D> 5m, D> 1.5 B)
o foundations on pillars;
o foundations on caissons;
o foundations on bars (moulded walls).
An evaluation of the economic efficiency of different foundation systems adoption can be
made according to Table 3.1.
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Table 3.1. Direct and indirect foundation structures
Superstructure Foundation structure
Cost
small environmen
t high
very
high
Bearing
masonry
- Rigid strip foundations;
- Continuous concrete foundations;
- The independent foundation
supports;
Structural Walls
- Rigid strip foundations;
- Reinforced concrete foundations;
- Reinforced concrete slab
Frames
- Isolated rigid foundation;
- Insulated concrete foundations;
- Tumbler foundations;
- The continuous beams
foundation;
- Reinforced concrete slab
Regardless of
the structural
system
Foundations on pillars;
Foundations on open caissons;
Foundations on straps
3.2. The compliance of the infrastructural resistance
The structural system of the building means all the elements of construction which ensure
durability and stability under the action of static and dynamic loads.
Structural elements can be grouped into four subsystems:
S - body;
B - substructure;
F - Foundations;
TF - The plot of the foundation.
For the selection of the type of foundation the geometry of the building elements, the type
of superstructure, the materials used and the mainly the sensitivity of the structural system to
compaction are required.
The framing of the foundation soil in one of the two groups of great importance for the
choice of the foundation system, direct or indirect foundation and for the choice of type of
foundation.
For a better understanding of the behaviour of different types of ground under the
influence of external loads, an analysis of different types of ground is made in Chapters 3.2.3.
14
The infrastructure conditions affect an important weight among the factors that can
influence the behaviour of the building and the neighbouring buildings. The following factors
have been highlighted:
The depth of excavation and the means of ensuring the stability of the excavation;
The existence of an aria of influence of the excavation at some buildings;
The existence of groundwater and draining system.
Independent foundations apply to structures with reinforced concrete pillars and metal.
They can be also used for continuous structural elements, if the structure is designed considering
the concentrated boundaries.
The types of independent foundations are classified in terms of the nature of the material
from the running superstructure.
Another classification of independent foundations can be made depending on the nature of
the structural element (monolith or prefabricated) in:
- Tumbler foundations;
- Other types of foundations, according to the joint pole–foundation system.
Fig. 3.8. Tumbler foundation for prefabricated pillars
Outside the monolith tumbler foundation, they can be executed:
- Prefabricated Tumbler foundations;
- Foundations with prefabricated tumbler.
For metal poles they can be adjusted to one of the following types of foundations, Fig.
3.12:
- Foundation blocks and bushings;
- Sole type of reinforced concrete foundations.
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Fig. 3.12. Foundations for metal posts
Continuous concrete foundations shall be adopted under continuous rows of monolith
concrete pillars, Fig. 3.13.
Fig. 3.13. Continuous concrete foundations
For soil prone to significant differential subsidence and where an increase of structural
rigidity of the overall plan of foundations cannot be done, the continuous foundation system, on
both main directions of the building is used, Fig. 3.14.
Fig. 3.14. Continuous concrete foundations in two directions
By adopting a system of columns fixing (tumbler, anchor bolts, etc.) continuous
foundations can be used for precast concrete columns, Fig. 3.15 or structures with metal poles.
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Fig. 3.15. Continuous foundations for precast concrete columns
A classification of the types of structural foundations in masonry wall constructions can
be made by the construction height:
- Ground floor + floor buildings;
- Buildings with basement.
For buildings without a basement, for the interior walls, depending on the geotechnical
conditions of the site, one of the following types can be used:
- Block foundation with one step, Fig. 3.16. a;
- Block foundation with two or three steps up, Fig. 3.16. b;
- Socket block foundations, Fig. 3.16. c.
a b
Fig. 3.16. Foundations for buildings without basement, b and c
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For the exterior wall foundations, the composition and safety features will be considered,
thus we have:
- Block foundations under the outer wall, Fig. 3.17. a, b;
- Cap and block foundations, Fig. 3.17. c);
- Foundations for exterior walls made of brick masonry, Fig. 3.17. d.
a c
b d
Fig. 3.17. Foundations under exterior walls
For buildings located in difficult terrain, as defined in Chapter 3.3 and where uneven
subsidence’s are to be expected, you can choose two structures of foundation:
- Foundations belts at the top (PUCM) or at the top and bottom, Fig. 3.20. a, b;
- Foundations which with superstructure and infrastructure form a special rigidity of
the assembly, or a flexible structure adaptable to large deformations.
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a b
Fig. 3.20. Reinforced concrete belt foundations
For the construction of reinforced concrete structural walls, two types of foundations can
be used:
- Rigid foundations of the concrete base bushings type, Fig. 3.21.;
- Elastic foundations, Fig. 3.22.
Fig. 3.21. Rigid foundations of the Fig. 3.22. Elastic foundations
concrete base bushings type
General rafts can take the following constructive solutions:
a) General raft type slab, with or without embedded beams, Fig. 3.23.a;
b) General raft, mushroom slab floor type, Fig. 3.23.b;
c) General foundation plate and beams, on one or two directions, Fig. 3.23.c;
d) General foundation plate with vute, Fig. 3.23.d;
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e) General foundation box, Fig. 3.23.e.
a b
c d
e
Fig. 3.23. a, b, c, d and e: Flasks concrete
The following foundations types are used as indirect foundation structures:
- Foundations on micro pillars d300mm;
- Foundations on pillars d = 300mm - 600mm, d> 600;
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- Foundations on caissons, prefabricated;
- Foundations on open caissons;
- Foundations on the caissons with compressed air;
- Moulded wall foundations;
3.3. The main types of ground and their behaviour under the action of disturbing
factors
Soil is defined as a type of sedimentary rocks, debris, with uncemented links in between
the solid fragments. Grounds that make up the foundation soil are identified and classified by
physical characteristics – mechanical characteristics, determined by laboratory tests or by on the
scene tests.
The plot of the foundation is composed of layers of soil with distinct geotechnical
parameters. Based on laboratory tests or / and the ground tests the ground stratification is
delimited, in plan and section, with certain limits in between the variables.
The accurate evaluation of the foundation soil stratification and of the geotechnical
parameters of each layer is particularly important for choosing the foundations’ structural system,
and to assess possible degradation at the foundations.
Soils are classified according to several criteria; the main criterion is the grain size
fraction.
Basic soils are the soils which have which are formed of uniform grains as specified
depending on the maximum size of the predominant grain.
Another classification based on the behaviour of the soil under the action of external
factors and external loads (request dynamic, changing humidity cycles frost-thaw, etc.) divides
the soils in 3 groups (NP 074-2007)
- good soils;
- medium soils;
- difficult soils.
The existence of the foundation ground of one or more types of soil, requires an analysis
mainly to test the behaviour under the influence of external loads:
- uncohesive soil:
o sand;
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o gravel and blocks (cobble).
- cohesive soil:
o clays;
o sandy soil.
- rocky rocks:
o sandstone;
o schists;
o clay soils;
o chalk;
o Limestone.
- Soils with special conditions of foundation are: soils whose behaviour under the
influence of external loads are not normal under the action of loads transmitted by
foundations.
Their determination should be based on several factors:
- Technical conditions;
- Ground conditions;
- Conditions of execution.
The most important factor that classifies the soils in the foundation soils with special
conditions group are the difficult soils.
A distribution of these types of soil in Cluj-Napoca is presented in Figure 3.36.
22
Fig. 3.36. Contractile soil areas in Cluj-Napoca
The following types of soil can be considered in this group:
- Loose sand and gravel;
- Liquefying sands and sands susceptible of liquefaction;
- Fine soils with reduced consistency;
- Loess soils belonging to the group B of wetting sensitive soils;
- Clay soils with high swelling and contraction;
- Soils with high content of organic matter (OM> 5%);
- Sloping soils with potential downhill sliding;
- Saturated clay soils, strong compressible;
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- Gelive soils;
- Saltings soils;
- Fillings.
Based on the author's experience a macro zoning of organic soils in Cluj-Napoca has been
done, Fig. 3.39.
Fig. 3.39. Organic soil areas in Cluj-Napoca
24
A possible assessment of foundation conditions and of foundation structures for
constructions on organic soils is presented in Table 3.11.
TABLE 3.11. Possibilities of organic soil foundation
Name Description
A. Light centrically loads
construction
The foundation is made directly after a prior removal of the
vegetal layer;
The replacement of the fully organic soil deposit, with a
cushion of compacted local materials, or on the object surface;
The improvement of the soil deposit by embedding its mass
with a pillow or blocks of stone ballast (lamb head);
B. Statically determined
Constructions (with
articulated elements
articulated in between)
A replacement is performed with a deposit on the surface of the
ground, able to bare the object’s loads;
Boat type structure;
The puddling of the material is achieved by introducing blocks
of stone on smaller areas or all over world;
C. Construction admitting
large subsidence Directly, with drainage at larger depths (ship type);
D. Construction rigid Deep foundations with the discharge of any restriction
(foundations on pillars, caissons, bars)
It is further presented an indicative of foundation methods and organic soil improvement
in Transylvania, executed with / without the participation of the author.
TABLE 3.12. Foundation improvement methods and organic soil improvement
No. Method name Implementation stage Comments The cost
of work
1 Foundation on pillars
bearing on the top
Applied at:
- ACE CLUJ
- Military Hospital
- Extension of the
Academy Library
- BCR Bank Cluj
Solution verified in time as
the safest in terms of
stability and his discharge of
the subsidence of the peat
layers phenomenon.
high
costs
2
Foundation through a
cushion of earth,
ballast, stone
Applied at:
- Hypermarket Miercurea
Ciuc
- Student Hostel for UBB
- Treleborg Industrial
Hall
The solution proposed the
total removal of the peat
layer, only possible for a
thickness up to about 3m of
the layer and if located near
the surface soil. Expensive
solution whose quality
expensiv
e
25
depends solely on the
execution quality.
3 Foundation on wells
Applied at:
- UMF Hostel on Avram
Iancu Street
- Ursus brewery
Applicable solution to about
6 m depth, at this level
depending on the existence
of a resistant layer with high
bearing capacity.
expensiv
e
4
A slab foundation,
after the prior
puddling of the
natural soil
Applied at:
- Maestro Center Cluj
At this solution general
subsidence of up to 20-30
cm and considerable
differential subsidence are
expected.
average
costs
5
Direct foundation
layer of clay or peat
gravel underneath,
through a second
basement filled
Applied at:
- The UBB –D Hostel
- Sinterom Hypermarket
Uneconomic solution,
dependent on the existence
of relatively small depth of
on this good foundation
layer and on its bearing
capacity
Very
high
costs
6
Foundation with rock
embedment in the
peat layer or in banks
(rock jam)
Applied at:
- Hypermarket in
Miercurea-Ciuc
Cumbersome solution,
achievable through knocker
battery (5 to).
The results are difficult to
assess, without the
realization of a puddling of
the layer of peat or mud but
its side discharge.
expensiv
e
7 Foundation through
concrete cores
Applied at:
Cipariu market,
Intre Lacuri District etc.
Solution achieved by
vibration. The results
revealed the insufficient
capacity for buildings with
multiple stores (12N).
high
costs
8
Through ballast
foundation plots
(vibrated, vibrated
twice, combined and
with concrete core)
Applied at
- Hypermarket in
Bucharest
Solution with good results expensiv
e
3.4. The effect of the groundwater
The high level of underground water can cause several phenomena that influence the
stability of the building, and also on the cost of the work. Several phenomena can be shown [81]:
o The phenomenon of negative pressure (UPL), which can lead to hydraulic fracture
26
at the excavation bottom;
o The phenomenon of swelling of the bottom of the excavation (HYD);
o The negative pressure effect on underground constructions or on the construction
frame foundation;
o The effect of uncohesive soil subsidence under the effect of drain works.
The high level of underground water can cause several phenomena that influence the
stability of the building but also the cost of the work.
The water under-pressure has a very important effect on the stability of tall buildings:
wind-driven electric power stations, funnels, TV towers etc. The effects of water negative
pressure lead to a significant decrease in the value of the vertical charges resulted on the foot of
the foundation.
3.5. The effect of running building conditions
The implementation of deep digging (H> 5m), in urban areas, has the most important on
the neighbouring constructions. Foundations located in the area of influence of vertical
excavation may suffer deformation.
3.6. Technologies used on the construction foundation in difficult
foundation terrain
The difficult foundation terrain represents the most significant group of the special
foundation conditions
The construction emplacement on such soil location requires the approach of special
foundation technologies.
Beside of the soil type influence which can be found in the foundation terrain, from the
author’s experience, other risks that may arise on a site, should be evaluated. The main objectives
that need to be pursued are:
o Obstacles that present seemingly risks and require special attention;
o The presence of neighbouring constructions (the quality of the foundations, the
depth of the foundations etc.).
o The nature of the fillings from the coatings (organic material, crushed or broken
bricks etc. which contain sulphur. The presence of slag, coal);
27
o Possibility of soil slides’ emergence.
The choice of the foundation solution, to sites with difficult foundation ground, can be
made using one of the solutions described below:
- Independent foundations/ continuous on pilots;
- General foundation raft on pilots;
- Independent foundations / general strike straps;
- Direct foundation systems on improved soil.
Due to the broad use of the system, I consider that a presentation of the methods and
technologies, used in foundation ground improvement both by past experience but also for future
experience, to be necessary.
The TC17 Technique has given a more extensive classification of soil improvement
technologies, Table 3.19. According to it the soil improvement technologies are classified in 6
groups [7].
Table 3.19. The classification of the improvement methods adopted by TC17
Category Method Principle
A.
Improvements
of soil without
additives; in
uncohesive
soil or fillers
A1. Dynamic
compaction
The puddling of granular soil through
compaction with the heavy knocker
A2. Vibrated
compaction
The puddling of granular ground by using a
vibrator inserted in ground
A3. Compaction by
explosion
Shock or vibration waves generated by
explosives, so that it would cause the granular
soil stabilization by liquefaction or
compaction
A4. Compaction through
electric shock
The puddling of granular soil through shock
waves and using energy generated by
electrical pulses under ultra-high voltage
A5. Compacting the
surface (including the
impact compaction)
The compaction of soil filling from the surface
or of depths, using a variety of compaction
equipment
B.
Improvements
of soil not
containing
cohesive
material
B1. The replacement /
dislocation (including
reducing of the load
using lightweight
materials)
The replacement of inadequate soil by
excavation or displacement and its
replacement with good soil or gravel. Some
lightweight materials can be used as fillers to
reduce the load on the soil.
B2. The pre-loading
using fillers (including
the use of vertical
drains)
Filling is applied to compressible soil in order
to pre-consolidate so that the compressibility
would be greatly reduced when future loads
are applied
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B3. The pre-loading
using the vacuum
(including fillings and
vacuum combination
between)
Vacuum pressure up to 90kPa is used so that
compressibility is reduced when future loads
are applied
B4. Dynamic
strengthening with
drainage (including the
use of vacuum)
Similar to dynamic compaction by providing
horizontal and vertical drains (or together with
the vacuum) are used to dissipate the pore
water pressure generated during compaction in
ground
B5. Electro-osmosis or
electro-kinetic
consolidation
DC currents cause the flowing of the water or
of the liquids in soil, from the anodes to the
cathodes, installed in ground.
B6. Thermal
stabilization using the
warming up or the
freezing of the soil
Changing the physical or mechanical
properties of permanent or temporary soil
through the warming up or through the
freezing of the soil
B7. Hydrodynamic
compaction
Loess soils are compacted by a combined
method of wetting and explosion with drilling
in depth
C.
Improvement
by soil
additions or
inclusions
C1. The Vibro-
replacement or columns
of ballast
Drilling of holes in with loose grounds and
filled with ballast or sand compacted to form
columns
C2. The dynamic
replacement
Aggregates are introduced in ground by strong
dynamic impact so that it would form
columns. The filling can be sand, ballast,
gravel or rubble
C3. Compacted sand
pillars
The sand is introduced in the ground with a
metal column and compacted by vibration,
dynamic impact or static load, as to form
columns
C4. Geotextile limited
columns
The sand is placed in the holes drilled in
geotextile cylinders, to form columns
C5. Rigid inclusions (or
composite foundations)
The use of rigid or semi-rigid pillars or
columns that are prefabricated or formed in
situ in order to improve the soil
C6. Columns or
embankments reinforced
with geosynthetics with
pilots
The use of pilots or of rigid or semi-rigid
columns, surrounded with geosynthetics in
order to enhance stability and to reduce the
embankment instability
C7. Microbiological
methods
The use of microbiological materials in order
to change the soil by enhancing its resistance
and reducing its permeability
C8. Other methods
Unconventional methods such as sand pilots’
forming by blasting and the use of bamboo,
wood and other natural products
29
D.
Improvement
of the soil with
additions such
as cementing
D1. Cementation
Soil cementation or cementation of the
granular cavities or cracks in soil or rocks, by
injecting cement or other solutions to increase
the strength and reduce the permeability of the
soil
D2. Injecting chemicals
The solution consists of injecting two or more
chemicals in the ground’s pores to form in gel
or solid matter in order to increase resistance
and reduce the permeability of the soil.
D3. Mixing Methods
(including pre-mixing or
mixing in depth)
Weak in-situ soil treatment by mixing with
cement, lime or other substances using a
mixing device or before the emplacement
D4. Jet grouting High-pressure jets at depth erode soil and
inject cement to form column straps or walls
D5. Cementation by
compaction
Very rigid cements, such as mortar are
injected in certain areas and remain in a
homogeneous mass thus increasing the density
of the soil
D6. Cementation by
offsetting
Particles in suspension of medium or high
viscosity are injected into the soil, between an
excavated subsurface and a structured in order
to eliminate or reduce building settlement
taking into account the running the
excavations.
E. Soil
reinforcement
E1. Mechanically or
geotextile stabilized soil
Using the tensile resistance of various types of
structural steel or geosynthetics materials to
improve the shear resistance of the soil and the
stability of the roads, foundations,
embankments, slopes or retaining walls
E2. Using anchors
Using tension resistant anchors in order to
improve the stability of slopes or retaining
walls
E3. Biological methods
using vegetation
The use of the roots of vegetation to stabilize
slopes.
F. The
replacement of
the soil
F1. Pillow or mattress of
stone or improved soil
(geosynthetics)
3.7. Solutions for the improvement of the bearing capacity of the road bed
According to the definitions of SR 4032-1-2001, the improvement layer of the foundation
is the material used to increase the bearing capacity of the embankments’ foundation and other
structures of the highway. Thus at the level of the road bed, appropriate or inappropriate material
may be found.
30
The selection of the method will be based on economic and technical considerations, and
graphic of the works.
The most efficient solution, in terms of the execution time, is the stabilization with earth
binding materials.
3.8. Assessments of the economic efficiency of the weak soil improvement
systems
The applicability of the weak foundation soil improvement system is an important criterion
in the economic efficiency evaluation of the solution. Based on the possible areas of use of the
improvement systems, choosing the most economic solution must take into account the
sustainability of the system.
The choice of improvement or consolidation of the foundation soil must take into account
several criteria:
Type the earth;
Advantages and disadvantages of the system;
Possibility of using local materials (fillings);
Type of construction;
Technical equipment of the manufacturer;
Manufacturer experience.
All these criteria can be considered only after knowledge of the advantages and
disadvantages of technology improvement and the mechanism by which it contributes to
increasing stability and limiting deformation.
Table 3.31. Methods used to improve soil in Transylvania
Method Name
Applicable to various types of soil
Eco
nom
y
Status of
implementation in
Transylvania
(Cluj xx)
Loess
soils
Loose
sand
Mud
and
soft
clay
Unorganized
fillings
Dusty,
loose
soil
1. Pillows
1.1.Soil x - - x x CN xx
1.2.Granular
material x - x x x CNI xx
2. Surface
compaction
2.1. Heavy x x - - - CMA x
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knocker
2.2. Knocker
super-heavy x x x x x CMA
2.3. Vibro-
knocker x CMA x
3. Compaction
in depth
3.1. Ballast
Columns x x x x x CME x
3.2. Vibro-
flotation - x - - - CMA
3.3. Vibration - x x x x CME x
3.4. Deep
Explosions x x x - - CM xx
3.5. Ballast - - x - x CN xx
4. Injection
4.1. Silicating x x x FM xx
4.2.
Cementation x x x x FM xx
5. Geosynthetics x x x CME xx
Note: CN - negligible cost;
CMI - low cost;
CME - average costs;
CMA - high costs;
MFF - high costs
The work experience of ACI CLUJ SA, during its existence of over 59 years, showed that in
addition to conventional technologies, (MPB, MCD, etc..) solutions to improve the quality of
compaction can be addressed also.
Knowing the advantages and disadvantages of these methods is necessary in order to
address future improvement technologies of the foundation soil, in both the study and the quality
performance enhancement and in terms of cost optimization.
3.9. The sustainability of the foundation works
Determining the costs incurred by the company for a construction, can be done by studying the
ecological parameters that appear in the execution cycle, including mining extraction, raw materials,
basic materials, building materials industry, installation and maintenance, etc.
Performance parameters associated ecological foundations or foundation soil consolidation are:
a.) The energy content of materials that make up the system;
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b.) The amount of water required for processing materials;
c.) The need for gravel crushed stone, stone blocks, etc.
d.) Pollution during construction;
e.) Labour costs for materials processing, transport, construction;
Sustainable construction has been identified as one of the future trends of the European market.
And that, due to the potential for innovation, ability to meet market needs, etc. To meet these challenges
is in need of innovative construction systems of all structures. The effect of these interventions is in
proportion to the building structural system.
3.10. Technical and economic considerations - foundation choice on
improved soil
The construction settlement is decisively influenced by the foundation soil properties and
the nature of its geological structure and the importance and purpose of the construction. The
tendency to spend as little as possible on the settlement of the building on the ground has led to
the use of so-called "foundation grounds"; the link between building and soil is usually
accomplished through the surface foundation systems, whose share of the total cost of the
construction represent 15% and 12% as working time.
The development of population centres, industrial areas and the exploitation of natural
resources, related to environmental protection, increasingly requires the location of buildings in
areas where physical and mechanical properties of the ground are difficult. Fended in the natural
deposits, these soils offer adverse conditions to the foundations effectuation. They usually lead to
higher costs for providing infrastructure, sometimes reaching up to 40% or more of the total
weight of the works, due to the use of deep foundation systems.
In the recent decades, the foundation on difficult terrain, characterized by low deformation
and mechanical properties, and the macro-pore soils, there is a tendency to replace the indirect
foundation systems with various methods to improve the soil on the depth of influence of
foundations, on whereon is then made, the surface foundation system.
The possibilities and foundation solutions that can be applied, if difficult terrain appears
on the site, depend on: the nature and properties of the difficult terrain, the thickness of this layer
and the position of the natural stratification of the deposit, the size of the loads transmitted by the
construction and their nature, and the technical scope for bringing into effect the foundation.
33
One decisive factor the completion of the foundation solution is represented by the layer
position and the depth of the difficult terrain.
If the difficult foundation terrain is composed of soil granular, fine sand dust, dust and
loose sand in saturated state, we obtain good results by carrying on depth enhancements by using
the vibration technique.
When designing foundations on improved soil, it has to be considered that the effective
pressure on the foundation sole would not exceed the bearing capacity of the improved soil, by
establishing testing on plate or natural size foundations and we have to ensure that at the contact
of improved soil with the difficult terrain, it is not exceeded the bearing capacity of the difficult
foundation terrain; the calculation being made to the limit state of deformations.
Chapter 4 – Recommended methodology regarding the quality –efficiency-conditions of
foundation
4.1. Using multi-criteria analysis methods in order to develop decision
The development of the decisions must be made with great responsibility, using appropriate
analytical tools and methods. Both investors and designers are forced to choose the “optimal"
solution for a variety of options on the market.
In 1960, the multicriterial analysis has appeared, in order to facilitate the decision developing
on the applicable solution. It is used for comparative analysis of alternative projects or different
criteria or objectives. Through the multi-criteria analysis, several objectives, in complex situations,
can be taken simultaneously into account.
Since there is no perfect solution, the solution that best fits the requirements of the investor
will be chosen; this actually being a compromise between all the requirements of the investor.
Generally, the multi-criteria analysis should be organized as follows:
- objectives must be expressed in measurable variables - they should not be redundant, but
may be alternative;
- once the "vector targets" have been built, a technique for information aggregating has to
be found, in order to make a choice; to the objectives, a weight reflecting the relative
importance assigned must be rendered;
- defining evaluation criteria - these criteria should relate to the priorities followed by the
different subjects involved or should refer to particular aspects of evaluation;
34
- impact analysis - this activity is to consider, for each of the criteria chosen, the effects it
produces, and the results may be quantitative or qualitative;
- the estimation of the effects of the investment in the selected criteria;
- the identification of the types of subjects involved in the investment and the collection of
such preferences (weight) given to various criteria;
- The aggregation of the scores of the different criteria based on the revealed preferences –
each score can be aggregated giving each a numerical rating of the investment,
comparable to other similar investments.
Among the many multicriterial methods which are used in the world, the ELECTRE
(Elimination Et Choix Traduisant Real) method family, developed by the French school, has been
chosen.
4.2. The ELECTRE 1 method
The ELECTRE 1 method belongs to the selection problem. The problem arises in terms of
choosing the best of the actions.
It is based on exploiting the relationship of surpassing, which is a binary relation defined on
the A set of actions and whose meaning is: an action ai outperforms an action ak if it is possible to
say with convincing arguments, that for those who decide ai is at least as good (or not worse) than
ak.
4.3. The choice of technology of foundations implementation using
multicriterial analysis
Multicriterial analysis using the ELECTRE 1 method and we intend to choose the best
foundation technology.
In carrying out the ELECTRE 1 method through 4 stages have to be completed.
Stage 1
It sets out the decision and makes an inventory of all potential actions.
Step 2
In this stage, the criteria need to be chosen, that will be the basis for decision making. The
method recommends that their number shouldn’t be higher than 10 and that they should be coherent,
comprehensive and non-redundant.
35
It should be emphasized that the share of each criterion is subjective: it express the will or
the policy of the one called to decided and can be remote from individual to individual.
Step 3
To assess the actions, a scale instead of numerical grades is used: very good (FB), good (B),
medium (M), satisfying (S) and unsatisfying (NS).
Because of the calculation of the discrepancy indices, numbers are needed, conversion of the
grades to numbers is necessary.
Based on the values in the performance tables and after converting the grades to numbers, the
numerical performance chart is established.
Step 4
In this stage, the calculation of the concordance index, of the discordance index and the final
choice sensitivity analysis are made, using the relationship of surpassing.
The calculation of the concordance index is made by dividing the weighted sum of the
criteria concordant with the hypothesis on the weighted sum of all criteria.
The calculation of the discordance index represents the ratio between the largest discrepancy
in relation to the hypothesis and the length of the largest scale that has been used.
An action surpasses another if it is at least as good as the other in regard to the most of the
criteria, without being too much inferior to the other, relative to the rest of the criteria.
The main steps that are taken in order to solve a multicriterial problem are:
It is determined the decision subject and an inventory of all potential actions;
It is determined the family criteria that decision will be based on and the weights are
assigned;
Every action is assessed through each of the criteria and the scales of evaluation are
established;
The aggregation procedure is performed.
The concordance thresholds, respectively the discordance thresholds function like filters,
each refining the core of the "good" activities. A current practice is to demandingly start the
sensitivity analysis, with stringent thresholds, in order to detect what is stable in the nucleus,
followed by a relaxation in order to extend the area of focus.
Multicriterial methods are a powerful and subtle analysis tool where it comes to the choice in
between several possible options. In this context, ELECTRE 1 method is a method of "common
36
sense", based on realistically concepts. Unlike the classical weighted average, it brings more clarity
through the game of choosing weights and scales, allowing a sensitivity analysis, by testing various
scenarios.
Chapter 5 – The analysis and presentation of constructions
With special foundation technology
5.1.The DN1, Cluj-Napoca – Huedin rehabilitation
The DN 1 Rehabilitation Project provides the rehabilitation of 53.9 km of road, between
Cluj and HUEDIN and it consists of the road expansion to a platform of 10m, a length of 42.6 km
and a platform of 12m on a length 11.3 km.
For the execution of the road works, four technical solutions were designed and applied on
different sections, as follows:
Solution no. 1 - reinforcement of the existing road system by maintaining the old
road system.
Solution no. 2 - reinforcement of the old road system by maintaining only the
foundation layer of concrete and milled cement-bound macadam.
Solution no. 3 - reinforcement of the road system by maintaining the existing
pavement layers as the basic layers of foundation.
Solution no. 4 – reconstruction of the road system.
As I described in the previous chapter, the ELECTRE I method has been applied for this
example.
5.2. Commercial space hall type in the city of St. George
The hall type commercial space is located in the eastern part of the town, between the Olt
embankment and DN12.
In order to establish the foundation solution for this objective, a geotechnical study has
been made. In accordance with the NP 074 normative 7 drillings at a depth of 8 - 11m and heavy
dynamic penetration tests (DPH) have been executed in July.
The ground prospecting was completed with two heavy dynamic penetration tests (DPH),
both performed on the southern platform (DPH1 + DPH2).
37
The tests for determining the mechanical characteristics of the equipment were made
using the Zorn ZFG 02 equipment.
In order to determine the road bearing capacity, a deflectometer with the Benkelman
anchored lever have been done. A total 46 tests were on 5 strings in the car-park, 10 in the
docking area and 12 on the road.
Solutions for foundation systems suggested by the design:
Solution 1 – Direct foundations on improved ground with columns of ballast of
60cm diameter and length of 6.6 cm at a minimum, recessed at least 0.70 m in
sandy gravel layer – level 518.00.
Solution 2 - Foundations on pillars of reinforced concrete run by the Bachy
Soletange method.
Solution 3 – Direct foundations on improved ground with columns of cemented
ballast of 60cm diameter and length of 6.6 cm minim, recessed at least 0.70 m in
sandy gravel layer – level 518.00 without cement paste injection.
And in this instance the ELECTRE I method has been applied in order to choose the best
foundation technology for these works.
5.3. Emergency Military Hospital "Dr. Constantin Papilian "
In the Emergency Military Hospital "Dr. Constantin Papilian "of Cluj-Napoca, street Gen.
Traian Mosoiu no. 22, we executed a new pavilion for medical activities.
Fig. 5.9. Emergency Military Hospital "Dr. Constantin Papilian "
The pavilion for medical activities is located in the built area of Cluj-Napoca, in an area
completely systematized. Between the boulevard and the barracks courtyard there is a difference
38
of approx. 7.5 m, where the basement and ground floor pavilion for medical activities are
situated.
For the design, the geotechnical study that has been conducted at the site, where the
conventional base pressure is Pconv = 190kPa, was considered. Because of this two methods
were suggested: the performance of a system with general slab foundation on drilled pillars and
the enforcement through a ballast cushion of 1.5 m thickness. The bottom slab rests on concrete
pillars with a diameter of 600mm and 800mm.
By using the multicriterial analysis ELECTRE 1 method, we focused again, on choosing the
best foundation technology for these works.
Chapter 6 - Conclusions and the author's personal contribution
6.1. Conclusions
The worldwide population growth, especially in big cities has a major impact on the soil
use for construction and at same time, on the safeguard of the environment. These issues require
the economic use of the existing soil, putting special emphasis on the use of unsuitable grounds
for building.
The sustainable development problem requires besides the balanced management of the
soil surface, the protection of the environment from chemical and physical degradation and the
efficient use of the mineral reserves which Earth provides us. Finally, it requires that the
technologies that we develop for producing them and activating the building materials, the carbon
emissions, dust and power degradation, not to lead to the degradation of the living conditions and
the depletion of mineral resources.
People have done various constructions since the prehistorically period and technologies
were enhanced over time.
When discussing about constructions, the first things that come to our thoughts are
buildings, bridges, viaducts, underground constructions etc. But the foundations stand on the
basis of all constructions; they are less visible, but with great advocacy to their quality and their
lives. The construction technology development both worldwide and in Romania was strictly tied
to the development of foundation systems. The multitude of solutions of foundation underlying
,the nature of the foundation soil, the dimensions of the loads, are generally influencing
foundation solutions, contributing to the expansion execution duration and to increased
39
infrastructure costs. It requires the search for new solutions, new technologies that shorten the
ensuing performance and economic efficiency.
However, these issues cannot be achieved without implementing a total quality
management system, with three objectives: quality, production and motivation.
Construction works, through their complexity and diversity, are demanding for a great
effort from the designer and from the contractor, in regard of the quality assurance of the works.
The analysis of the foundation system conditions - Efficiency – Quality primarily requires
an assay of the behaviour of the types of soil, under external loads. The soil types that require a
more careful research are the difficult foundation soils, the soft and the weak soils. Knowing their
behaviour under external loads or under the external factors, can offer an image on the manner of
influence of their behaviour. An important soil category of the difficult soils is represented by the
organic soils. The foundation possibilities of the organic soils and the establishment of their
behaviour improvement technologies are to be assessed primarily, on the experience acquired
through executed works.
One of the most effective foundation solutions in difficult terrain of reduced / medium
depth is the foundation on pillars solution.
Currently, a relatively high number of the pillars execution technologies exist in the world;
in Romania the technologies with a global frequency greater than 14% are being frequently used.
For medium and large thicknesses of the difficult terrain, an economically viable
foundation alternative consists of the surface foundation on improved ground.
The methods of soil improvement are divided into at least three categories: temporary
improvements, the filler material consolidation and the permanent treatment. Within each of the
categories, improvement methods were developed based on principles that advert to soil
properties’ modification.
The knowledge of the main technologies within each of the categories is important not
only for the evaluation of the economical level of the improvement systems but also for the
estimation of the advantages and the disadvantages, of each of the methods.
The development of constructions on difficult terrain represents an obstacle to the
beneficiary of the purposed construction. The pertinent analysis of the influence of the systems on
obtaining quality but also the entire construction process streaming constitutes a strict current
concern.
40
The proposal on the election foundation pertinent to the foundation systems’ solution:
indirect foundations or foundations on improved soil, through a multicriterial analysis, are leads
to the most efficient solutions for a construction.
From above aspects, results that the approach of the foundation system concept approach -
Quality - Efficiency, concerning any construction, constitutes an optimized, modern and of
internal nature refinement, for the researchers in this branch.
6.2. Personal Contributions
Among the personal contributions of the thesis, I am recalling the following:
The consultation of a bibliography of current theme in the ground of work,
including the latest legislation and technical literature;
A summary of construction progress in Romania;
A history of the foundation systems’ development;
The synthesis, systematization and analysis of the general concepts of quality of
construction works;
A summary of the types of foundations and an assessment of the economic
efficiency of their adoption;
The overview of the main types of soil and of the main difficult foundation soils,
assessing their behaviour under the influence of disturbing factors;
The characteristically mapping of Cluj-Napoca, in connection with the expansion
of the contractile soils and of soils with a high content of organic matter;
A summary of foundation possibilities, on organic soils and of the possible and
applied methods of organic soil improvement
The assessment of the possibility of the furnishing of the organic soil areas with
buildings;
The estimation of the cases of intervention to works of slopes’ strengthening and
of the economic efficiency of their approach;
An appraisal of the economic efficiency of the pillar execution technologies’
adaptation;
The systematization and the classification of the foundation soil improvement
methods and an appreciation of the economic efficiency of the soil improvement systems;
41
A systematic method of bearing capacity improvement, of the road bed;
An analysis of the sustainability of the foundations work;
A proposed methodology regarding the quality-effectiveness- foundation
conditions’ system;
Case studies on the application of indirect foundation systems and solutions to
improve the foundation soil.
The application of multicriterial methods in public tenders.
The sequencing to construction quality measurement –the quality spiral.
6.3. Recommendations for future research
Studies addressing the influence of foundation construction on the quality and efficiency
are a broad ground for future construction industry preoccupation, namely:
Creating a foundation systems’ guide, based on two parameters: quality and efficiency;
Further calculations on using various economic strategies;
Extending the studies applicable to introducing simplifying assumptions on approaching
actual multi-criteria analysis;
Studies and researches on the use of multi-criteria analysis in the construction and putting
this analysis into effect at public auctions;
The application of multicriterial analysis to choice of equipment and suppliers;
Risk estimation.
Cluj-Napoca, August 2011 Eng. Dorin Aşchilean
