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Foundation Design
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An-Najah National University
Engineering College
Civil Engineering Department
Design of Foundation forNablus Industrial School""
Submitted bySameh Jamal Zalmout
SupervisorDr. Sami Hijjawi
Introduction to Foundation
A foundation is a structure that transfers loads to the earth.
Foundations are generally broken into two categories
Types of Foundations
1 -Shallow Foundation
2 -Deep Foundation
Shallow Foundation
1 -Spread Footing
2 -Mat Slab
3- Slab on grade
Deep Foundation
2-Pier and grade beam foundation
1-Pile foundation systems
3-Specialty piles
Specialty Piles
1-Micropiles
2-Tripod piles
3-Sheet piles
4-Soldier piles
5-Suction Piles
6-Vibro Stone Columns
7-Piled walls
8-Pipe piles
12-Screw Piles
11-Timber Piles
10-Cylinder Piles, (hollow concrete piles)
9-Pre-stressed concrete piles
13-Platform on Piles
Project Description andGeotechnical Investigation
-The school consists 4 stories
-Plan construction area 606-1053 square meter in the first and second basement, and 902 square meter in the ground and first floors
-No ground water within the depth of the borehole
-6 boreholes
-The soil is high plastic silty clay layer
-The studied area is flat
ElevationSoil type
Depth(m)
B(m)
L(m)
C(KN/m2)
Ø(t/m3)Bearing
capacity(kg/cm2)
104.5(BH.1-4)
Silty Clay (CH)2.03.02.0361061.6
102.0(BH.4)
Marl2.03.02.03310201.8
106.0(BH.1-6)
Marl+gravel2.03.02.01221202.5
103.0(BH.3-2-5)
Silty clay(CH)
4.03.02.0301261.7
99.0(BH.1-4)
Marl+gravel5.53.02.0923184.7
Structural Analysis
Gravity loads divided into 2 types;
Dead Load (D.L)
Live Load (L.L)
Service load=1.2 D.L+1.6 L.L
D.L= Area (around column)*Slab thickness*Density of the concrete
Thickness of slab =0.4 meter
Density of the concrete =2500 Kg/m³
L.L= 600 Kg/m³
Mat Foundation
Mat foundation is a combined footing that may cover the entire area under a structure supporting several columns
and walls
Mat foundations are sometimes preferred for soil that have low
bearing capacity
The project consists of two
symmetrical mat foundation
The following figure shows the mat foundation (using sap2000 version 12)
Mat depth= 0.75 meter
!Fc =280 kg/cm²
Fy = 4200 kg/cm²
Column height = 3.5 meter.
Pile Foundation
Piles are long and slender members which transfer the load to deeper soil or rock of
high bearing capacity avoiding shallow soil of low bearing
capacity
Single Pile
The ultimate load can be carried is equal to the sum of ultimate resistance of the base of the pile and the ultimate skin friction over the embedded shaft
of the pile
Qs= (∑ (F*Cu*P))*ΔL
qp = Nc * Cu
Qp= qp*Ap
Q allowable= 3
Qs Qp
All piles used in this project was (0.7,0.8) meters diameter with
several lenghts
Total number of piles
105 piles
Settlement of piles
Se = Se (1) +Se (2) + Se (3)
Se (1) = elastic settlement.
Se (2) = elastic settlement due to load at pile tip.
Se (3) = elastic settlement due to skin friction (shaft)
Pile Caps
Pile Cap is defined as a concrete block cast on the head of a pile to
transmit the load from the structure to the pile or group of piles.
According to the nature and characteristics of the materials
encountered in the drilled boreholes (Fill materials with well
defined layers of high swelling silty clay at a shallow depth followed by marlstone and
occasionally boulders) ,
as well as the low soil bearing capacity, I suggest to consider the design of pile foundations for the building to reduce or avoid the detrimental effects of soil volume change (swelling and shrinkage) along the bored depth of the boreholes
Thank You