Maintenance of Roads in Deserts and Hills

8/7/2019 Maintenance of Roads in Deserts and Hills

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MAJOR PROJECTMAINTENANCE OF ROADS IN DESERTS &

HILLS

PROJECT GUIDE : Lt. COL.(RETD.) M.K.PANT (H.O.D) CIVILENGINEERING DEPT.


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World College Of Technology AndManagement

Farrukhnagar, Gurgaon

CERTIFICATE

This is to certify that the project entitled MAINTENANCE OF ROADSIN DESERTS & HILLS is a record of the bonfire work done by Mr.ASHOK DALAL (08/CE/07), Mr. HARISH LAMBA BY (19/CE/07), Mr.LALIT SHARMA (24/CE/07), Mr. MANOJ KUMAR SHARMA(26/CE/07) and Mr. PREETAM SINGH (37/CE/07), Ms. VIMMI BARTRA(75/CE/07) under my supervision and guidance. This report is submitted toWORLD COLLEGE OF TECHNOLOGY AND MANAGEMENTGURGAON in fulfillment of the credits requirements for the major project.

Lt. Col. (RETD.) M. K. PANTHead of Department CivilWorld College of Technology and ManagementGurgaon


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ACKNOWLEDGEMENTS

We express our sincere thanks to LT. COL. (RETD.) M.KPANT, Head of Department for his invaluable support,motivation and guidance for the entire duration of myproject and for explaining various constructiontechniques, specifications and tests. His practical

experience and exhaustible research experience morethan two decades help us a lot.


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MAINTENANCE OF ROADS IN DESERTS

INTRODUCTION Road maintenance in Deserts pose special engineering and

administrative problems due to following peculiarities of such areas:- The fine sand which is the main soil mass in such areas is highly

vulnerable to wind erosion and rain cuts resulting in extensive damagesto embankments and unpaved shoulders.

Excessive heat and scarcity of water during summer months. Strong wind storms and shifting sand dunes. Lack of vegetation and scarce population. Long leads involved in transporting good quality constructional

materials. Limited working hours due to extreme heat condition during mid

day causing sun strokes, exhaustion etc. The wear and tear on various components of veh/plant/eqpt are

comparatively more due to dry weather, high temperature ,sand , dust,heavy and strong wind storms, saline water etc. This calls for extra

precautions for maintenance of the machines.The above aspects, in so far these are related to road maintenance, arebrought out in succeeding paragraphs.

SAND DUNES The main item for maintenance of desert roads is the clearance of

sand months from May to August. If the road alignment happens to cutacross the primary sand dunes and make box cuts through such dunes.The problem gets compounded. With every sand storm, the sand gets

deposited on the road surface which requires a very heavy maintenanceeffort during the summer months. Such large deposit of sand on roadsurface creates serious traffic hazards.


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The incidence of road blockage on occurrence of sand dunes is

however far less if:- The alignment runs parallel to the sand dunes. The road crosses the sand dunes without disturbing their existing

natural profile.If the above two precautions are taken during the original

construction, the subsequent maintenance cost is far less.

TACKLING SAND DUNES

IDENTIFICATION OF SAND DUNES AND PLACEMENT OFRESOURCES AT VULNERABLE POINTS

Over the decades, the sand dunes have more or less establishedthemselves in certain areas. These areas can be identified and resources

placed near vulnerable places before the onset of sand storms so that anyroad blocks can be cleared with the least amount of delay.

CLEARANCE OF SAND FROM ROAD SURFACE

This can be done either manually or with machines like farm tractorequipped with a rear blade.

PLANTATION OF SHELTER BELTSA number of rows of trees and bushes should be planted on windward

side, about 15 mtrs away from road edge, at sand dune location, to act as


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shelter belts to reduce the shifting of sand on to the road surface.Suitable undergrowth in the form of low bushes ad grass can be plantedin the interspaces between rows of trees. 5 to 6 rows of trees are requiredto be planted about 3 mtrs apart.

These trees and bushes should be planted in early July and can bewatered for a period of 3 to 4 months and should be properly nurturedtill they are capable of surviving on their own. Grass can also be plantedover the sand dune area to provide ground vegetative cover.

PLANTS AND GRASSES SUITABLE FOR ARID ZONES

TREES Babbol Kumat Khejdi Farash Jal

GRASSES Sewan Dhaman Munj


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Murat

BRUSH WOOD BARRIERSLocal brush wood can be collected and barriers made on the surface

of the sand dune, sufficiently away from the road, to check themovement of sand. Such brush wood barriers will require regularmaintenance and repairs.

OBSTRUCTIONS ON LEEWARD SIDEAny obstruction even in the form of trees, bushes prevents the free

flow of sand. The sand drops down and accumulates near the base ofsuch obstruction. It is therefore, necessary that any obstruction. It istherefore, necessary that any obstruction near the road edge on the lee-ward side is got removed to avoid any accumulation of sand on the roadsurface or very near to it. Any accumulation of sand on leeward sideshould be removed urgently to avoid further accumulation on account ofthis obstruction.

In case any plantation is proposed to be done on the lee-ward side, itshould be sufficiently away from the road. Say 15 to 20 mtrs, to allowfree flow of sand.

CLEARANCE OF EXTRA WIDTHIt is advisable to clear width, say 10 to 15 mtrs on either side of theroad, so that even if some quantity of sand accumulates, it will be awayfrom the road and will not cause obstruction to the traffic. It will takesome time for the accumulation to reach the road surface, by which timeclearance arrangements can be made.

DOUBLE CARRIAGEWAY WIDTH AT SAND DUNESIn case, he underneath surface is hard, the vehicles can negotiate low

height sand dunes without getting bogged down. In this respect,providing double width carriage way at sand dune location is helpful. Incase, the fund does not allow such provisions, moorum or kankar can belaid on the shoulders to provide hard surface for the extra width.


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RAIN CUTSGULLY EROSIONThe sand is cohensionless and thus has high erodibility. Even with

scanty rains, gully formation takes place. The problem is more

pronounced in case of high embankments where the side slopes geteroded both due to rain and wind. High embankments in some cases areunavoidable due to crossing of sand dunes at summit points within thelimiting gradients.

REPAIRS OF RAIN CUTSFilling back the rain cuts with locally available sand does not provide

an effective solution. These rain cuts should be filled with moorum,kankar, gravel or any other hard material available nearby at reasonableleads. If stone is available nearby, it is so much better.

SHOULDERSThe worlds hit by rains are the shoulders on a desert road. Where-

ever funds permit, shoulders should be pave with moorum, kankar,gravel, stone or any other hard material available at reasonable distance.


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EMBANKMENT SLOPES The solutions for the rain cuts on embankment slopes are as

under :- Boulder pitching

Turfing by grass, bushes, shrubs etc. Brush wood barricading across the embankment slopes. Lining of chutes. Provision of edge walls or check walls. Asphalt Mulching.

BREACHES OF ROAD FORMATIONIn case breach in road formation takes place due to floods, it is not

advisable to build the formation again to the same level. The site shouldbe properly examined to find out a suitable technical solution. At suchlocations, a cause-way at the level of the bed of the stream could be amore suitable solution to provide safe cross passage to flood waters.

CONCLUSION At the time of finalization of the road alignment, it is advisable to

follow the lie of the land in keeping with the natural terrain. Suchroads will have less maintenance problems later.

Sand dune areas should be identified and resources placed atsuitable locations for speedy clearance e of road blocks.

Proper emphasis should be laid on plantation and providingvegetative covers for stabilization of sand dunes.

Lee-ward side of the road should be kept clear of any obstructionto avoid accumulation of sand dunes.

The protection against rain cut and wind erosion may call for provision of hard shoulders with suitable material, boulderpitching, lining of chutes, provision of check walls, turfing on side

slopes and creating brush wood barriers etc. Additional clearance in sand dune area for 10 to 15 mtrs on either

side of the road. Providing double carriage way width or at least paved shoulders at

sand dune locations to provide hard surface to enable vehicles tonegotiate low sand accumulation on the road surface.


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MAINTENANCE OF ROADS IN HILLY AREAS EXPERIMENTSON ROAD CUTTINGS IN NEPAL


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1. INTRODUCTION

Nepal is a small land-locked kingdom about the size of England,lying along the northern border of India in the Himalayan mountain

range. The Himalayan mountain belt is one of the most difficult terrainsin which to build roads: the first motor able road into the mountainsconnecting the capital, Kathmandu, to the plains in the south, wascompleted only in 1956.

A number of roads have now been built into the interior and theyhave all suffered from landsliding to a greater or lesser extent. Thedevelopment of instability above and below a road results in sterileagricultural land and contributes to the already serious loss of soil fromthe slopes into the rivers, creating problems of siltation and hydraulicdisturbance, often many kilometres downstream. The problems ofhighway design and maintenance in mountain regions are by no meansrestricted to Nepal. Population pressures, deforestation and soilerosion, are common in mountainous countries everywhere.

The aim of the research therefore goes beyond a need to reduce thecosts of clearing landslides and delay to vehicles. The methods underinvestigation are intended to develop low cost engineering solutions toinstability that are within the capability of indigenous resources in termsof materials, institutional organization and manual skills. It is hoped that


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the research will generate greater empathy between highway engineeringand community life in Nepal that could have implications for manyother countries.

The British government has funded the construction of two roads in Nepal, a 110km section of the East-West Highway from Butwal toNarayanghat that was opened in 1975, and a 55km road from Dharan toDhankuta, completed in 1982. After completion of the two roads, it wasevident that the Nepalese Department of Roads, while capable ofclearing landslides and repairing the road surface, could not provide theresources necessary for extensive and long term repairs to unstablehillslopes. The Overseas Development Administration accordingly setup a Roads Remedial Works Unit, in conjunction with the RoadsDepartment, under the management of Roughton and Partners,consulting engineers. The duty of the RRWU is to carry out repairs onthe two roads other than normal recurrent maintenance, for a period ofthree years initially. Roughton and Partners hire and supervise localcontractors to carry out the work.

The Overseas Unit of TRRL operates independently, in collaborationwith the RRWU. Shortly after the establishment of the RRWU in 1984,

TRRL visited Nepal to set up the experimental project and select sitesfor study. TRRL staff visit the sites at least once every year to monitorperformance and review the research programmed. To date the siteshave experienced one monsoon season.

2. ENGINEERING GEOLOGY

2.1 Geology

The development of the Himalayan mountain chain took place some26 - million years ago, although even today movement has still not


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ceased. The rate of rise of the land mass was so rapid (in geologicalterms) and the rate of downcutting by rivers so vigorous, that themountain slopes was left in a barely-stable state. The present climate ofhot monsoon conditions, with both high and intense rainfall, has resulted

in deep weathering profiles, on slopes that are near the limit of stability.Landsliding is so common that it can be considered the norm rather thanthe exception in this landscape. Intense rainfall causes severe soilerosion, aggravated by deforestation and farming of marginal land where

population pres-sures in the hill districts are high. More than threequarters of Nepal lies within the Himalayan fold mountain chain. Thecountry can be divided into four litho logical and structural units, threeof which affect the roads under study:

1) Terai: The Terai is an almost level alluvial plain, representing themost northerly extent of the Indo-Gangetic Plain. It is an area ofintense agricultural activity, the most productive area of Nepal.

2) Siwalik Hills: Rising sharply from the terai, the Siwalik Hillsconsist of sedimentary rocks. The hills rise to some 800 m in thevicinity of the Butwal-Narayanghat road.

The Dauney Hills are made up of sediments of the Siwalik group,


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consisting of alternating sequences of sandstones and mudstones, mostof which are micaceous and silty in nature. The rocks vary in thicknessfrom about 0.5 m to several metres, but are usually less than 1 m thick.In addition there are several beds of sandstone more than 20 m thick. All

the rocks areporous by nature and have been tilted and faulted toproduce much fractured rock masses that are highly permeable. Waterenters the joints and penetrates to a depth of many metres, creating deepweathering zones and lubricating potential failure planes. It also

permeates the body of many rocks, causing them to become internallyweak.

3) Mahabharat Lekh or Lower Himalaya: The metamorphic rocksof the Mahabharat are dissected into ranges of hills increasing in altitudeto the north. The Mahabharat rocks of the Dharan - Dhankuta areaconsist for the most part of metamorphosed phyllites, schists andquartzite. These rocks have been intensely folded and crushed duringmetamorphism, and now form shattered masses that are very prone toweathering and collapse.

4) High Himalaya: The great mountains of the Himalayan range.

2.2 Mechanisms of slope failure

A mechanism of slope failure is the process that causes onecomponent of a slope to move downhill in relation to another. Acommon misconception is that "the landslide" consists only of themixture of soil and rock debris that lies in the slide path and on the road.But the debris is only part of a much larger phenomenon, and it isnecessary to consider the slope failure as a whole if the slide is to be

permanently stabilized.


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The occurrence of a landslide event marks the start of a period ofactivity that may last at least several years, during which time thelandslide grows. The duration of instability depends upon the rock typeand structure, but sliding eventually diminishes as the landslideapproaches a stable angle, or stable rock planes are exposed. One largedebris slide, which was voluminous and blocked the road in the 1981monsoon, is dwindling now that relatively stable rock planes are

exposed in the head area.

To stabilize a landslide the source of supply must be identified and


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detachment from the hillside should be prevented wherever possible. Alandslide can be envisaged as consisting of three components. Sometypical mechanisms are illustrated in Plates 1 - 3.


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It is important to note that all the landslides contain more than onemechanism of failure. At the experimental sites great care has beentaken to identify which mechanism pre dominates in each part of a slide,its likely cause, and to decide which kind of remedial measure is most

economically appropriate at that point.

3. ORIGINAL ENGINEERING MEASURES

It is the practice in Nepal to protect the road pavement and side drainsby the provision of toe walls and cut-off drains.

3.1 Toe Walls

Two types are generally used. Where there has been a clear need toretain a soil or rock mass gabion walls have been constructed. These areof conventional design and construction, and rely on their deadweight toresist sliding or overturning. Gabions are especially appropriate for

Nepal because the nature of the design permitsconsiderable distortion to occur whilst still retaining material. Howeverthere are many instances where the wall has been overtopped, or where

buckling has been sufficient for individual wires to fail.

Toe wall

Where erosion at the toe of the exposed cut face was expectedrevetment walls have been employed. These have been constructed of


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dressed dry stone masonry blocks, strengthened by mortared masonry"frames". These walls fail where ground movement creates forces

behind the wall.

3.2 Cut-off drains

These drains have been provided in numerous locations and havebeen constructed of bound masonry with a trapezoidal cross-section.

Cut-off drains so constructed have two major shortcomings. Becausethey are necessarily remote from the road clearing of debris is oftenforgotten. Also the drain can fracture due to slight ground movement orimpact from a boulder. The inherent inflexibility of the bound masonryconstruction makes this more likely. Clogging or fracturing can result insevere concentrated erosion which may be worse than that which wouldhave occurred if the drain had not been built.

It is evident that the potential threat to new roads from instability wasrecognized by the original designers. Well understood techniques wereemployed to retain the small slides encountered. Structural failure hasmostly been due to subsequent changes in site conditions that were

unforeseen at the time of construction. It is not always possible topredict such changes but a clearer understanding of the mechanismscreating the instability may assist the engineer to make adequate

provision for them. Performance has also been affected by subsequentlack of maintenance. For this reason, experimental designs are suggestedwhich, as far as possible, require little or no maintenance.

4. EXPERIMENTAL TECHNIQUES

Nepal, like most developing countries, has very limited foreignexchange resources and a severe shortage of qualified engineers andtechnicians. This situation has limited the techniques to be tested tothose which:-

(a) utilize materials readily available in Nepal.(b) Require no knowledge of specialist techniques.


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(c) Do not require specialized plant and equipment.(d) Require minimal recurrent maintenance.These requirements have not been satisfied in every case. However, it

is believed that the techniques, if successful, can be modified to suit the

requirements of Nepal and similar developing countries.

4.1 Support structures

These structures may be required either (a) to retain a soil mass whichwould otherwise endanger the road pavement or (b) arrest the movementof surface material down slope which would otherwise damagevegetation, promote erosion or pose a threat to the road pavement orside drains.

4.1.1 Earth retaining structures

Earth retaining structures have generally not been recommended as asolution to land sliding because they do not tackle the problem ofstabilizing the source zone and halting the supply of material to thedebris slide. But there are occasions when a heavy retaining structure at

the toe is unavoidable. An alternative design to aconventional gabion wall is being tried which it is hoped will provideequally effective restraint at less cost. Cost reduction should be achieved

by faster construction and the use of unprocessed fill rather than the broken stone required for conventional gabions. There is also aconsiderable reduction in the quantity of gabionwire required for a given height and length of wall although this will be

partially offset by the need for other materials.

The construction proposed is illustrated in Fig 3. The wall comprisescylindrical columns abutting one another to form a continuous structure.Each column is formed by eight vertical steel bars wrapped in gabionwire and 'Lotrak' fabric. This fabric is being used because a quantity is


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available on site although geotextile fabrics are not made in Nepal. Ifthe design is successful an alternative to geotextile will be sought forfurther structures. The cylinders are filled with sand or gravel andcapped with concrete. The design of the cylinders provides a structurewhich:-

(a) Resists sliding due to its deadweight and the base being lowerthen the surrounding ground.

(b) Has a very high resistance to overturning.(c) Has a high resistance to deformation. Internal stresses are

transmitted to the skin which is cylindrical and taut. The concrete cap

resists vertical displacement of thefill.(d) Facilitates the escape of drainage water, through the narrow gapbetween cylinders.

4.1.2 Surface material restraint


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A simple modification to the design of the mortared frame revetmenthas been introduced at a site where differential vertical displacementmay occur. To accommodate this, while retaining the integrity of thewall, joints between the mortared columns were left unbounded.

Catch fences are a successful method of preventing erosion in loosematerials, and encouraging the growth of vegetation. Two types have

been developed, to suit the particle size of the debris. Where fine grainedmaterial predominates woven wattle catch fences have been installed.The fences must be placed horizontally to minimize concentration ofwater flow. The soil platforms form an ideal environment for plant

growth. It will be apparent that the fences have very little strength andcan be easily breached or damaged by scree or boulders. Where coarsematerial pre-dominates a wire fence, similar in principle to the wattlefence, has been introduced, illustrated in Plate 8. The wire fences have amuch greater resistance to damage, and can survive even when seriouslydistorted by large volumes of material.

4.2 Surface coverings

To arrest the erosion or weathering of relatively soft material with asteep exposed face where vegetation would be impossible to introduce arange of surface treatments has been devised utilizing locally availablematerials. All the techniques, except perhaps bitumen, are well-proven,

but the principal objective is to determine which technique is the mostcost-effective. Figure shows a site where they have been tried


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simultaneously as individual surfacing.

4.2.1 Bricks and masonry facing

One section of the site has been covered with bricks, laid flat withoutfurther keying. Another has been covered with a dressed dry stonerevetment. These surfacing are appropriate because brick is very widelyused as a building material in northern India where natural aggregate isscarce, and dressed stone masonry is a local skill in Nepal, muchexploited in the construction of walls and gabions.

4.2.2 Chunam and Ferro-cement

Chunam is a rendering composed of Portland cement, lime and clayeyweathered aggregate (1:3:20). It is applied in two equal layers 20 mmthick and keyed to the previously cleaned face by bamboo dowels

projecting from the surface. Weep holes are left to drain any groundwater from the protected rock as it is intended to providean impermeable surface. Ferro-cement is an alternative rendering placedin one layer composed of Portland cement and coarse, sharp sand (1:2).Adhesion to the previously cleaned face is achieved by fixing"Weldmesh" reinforcement or similar, overlain with 10 mm aperturewire mesh prior to application of the mortar. Weep holes are provided as

before.


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4.2.3 Bitumen

Bitumen has been successfully used in the past to hold seeds in placelong enough to allow germination to take place. In that case the bitumen

is required to adhere to the surface for only a relatively short time. Toresist erosion the material must bond successfully for many years.Observation of the technique in other parts of Nepal suggested that thiswould be difficult to achieve, particularly where moisture is present.Two applications of cutback bitumen have been applied using a handlance connected to a pump and tank. A very low viscosity cut-back wasused (MC30 or less) to ensure penetration of the first coat into the rocksurface. This comprised 60% 80/100 pen. Bitumen and 40% cuttingagent made from kerosene and diesel oil blended 3:1 respectively. Weepholes were built in to remove as much as possible of any moisture in therock.

4.3 Surface seals

With prolonged rainfall during the monsoon, water percolates toseveral meters into the soil. The effect is greatly exacerbated if slightground movement should occur, opening up cracks in the surface. An

inexpensive measure is to cover the cracks, to mitigate the effect ofwater running into open fissures, sufficient at least to give time for a fullappraisal of the landslide to be made, or for the slide to reconsolidateand stabilize itself.

Cracks may occur singly around the head of a slide, or all over amoving surface. For these bituminized jute covers are proposed. Cracksalso appear behind the head of a slide, for which roofing felt has beentried.

4.3.1 Bitumenised jute

Jute is indigenous to Nepal and is available as a woven fabric. Beinga natural substance it detoriates and rots rapidly in the presence of water


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unless protected in some way. To seal both individual cracks on a slopeand large areas of exposed ground, jute fabric has been sprayed with cut-

back bitumen and laid directly on the previously cleared surface. Thesame design principle is used for both single cracks and multiple cracks:the jute is secured on the upslope side only to allow further ground


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movement to take place without disturbing the covering. The covering isprotected from animal hooves and sunlight by a layer of loose stonerubble.

4.3.2 Roofing felt

Cracking occurs around the head of slide scars by collapse of theunsupported vertical face, causing the head to retreat rapidly. A methodhas been proposed of covering the 'brow' of the scar with roofing felt tokeep the brow area dry. The felt is resistant to sunlight and weathering.Strips are lapped to keep water out, and secured at the rear edge only toallow for some loss of material at the edge without disruption of thecover. The front edge of the cover is weighted to prevent wind damage,

and the whole protected with stone rubble as before. This technique hasmet with success in preventing the head ward retreat of a landslide. Thehead scar now forms an overhang where material has continued to fallaway at the base of the scar, presenting a further problem to be solved

before the head area can be considered stable.


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4.4 Drainage measures

The measures introduced are designed to improve the performance of

standard surface and sub-surface drainage methods. The main problemsassociated with cut-off drains are blockage by debris from higher up theslope, and cracking due to movement or impact. To reduce these effectsa simple steel mesh cover has been proposed which is hinged on oneedge to allow access for clearance. A fully flexible design was notconsidered to be feasible but, where cracking of the structure is a danger,channels have been lined with short overlapping lengths of roofing felt,laid transverse to the direction of flow. Minor cracking will not theneffect its operation. French drains are another well-tried technique, butthey are generally installed in ground that is not expected to move.Experimental drains have been laid in debris masses, wrapped in 'Lotrak'and wire mesh so that they retain their integrity even after considerabledistortion has occurred. Such drains can be laid in a landslide track whenfurther falls of debris are inevitable. The drain would then be buried, butcontinue to be effective in conveying ground water away from the debrismass.


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4.5 Vegetation

The effectiveness of vegetation in combating certain types of

instability is recognized. In relatively wet, tropical areas, naturalvegetation will usually be reestablished very rapidly, but this may stillleave substantial areas of ground exposed to erosion. Also, specieswhich naturally establish themselves most quickly may not be the mosteffective or desirable for improving stability or for future exploitationfor agriculture or forestry.

Local inhabitants make extensive use of vegetation as sources offirewood animal fodder and building: material. In many areas supply is

barely able to keep pace with depletion. It is hoped that if vegetation can be established on landslides and a management system introduced,surplus produce could supplement local supply, leaving sufficientvegetation to continue to provide erosion protection.

Vegetation


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5. MONITORING OF EXPERIMENTS

Two preliminary site visits were made by TRRL to make a

geotechnical appraisal of the mechanisms of failure that appear to betaking place, and to draw up a schedule of remedial measures for eachexperimental site. It is not possible to be certain about the mode ofdeterioration of a slide without observing it over a long period; thereforethe monitoring techniques are designed to collect permanent records forsubsequent analysis. Ideally, each experiment should be installed andleft to withstand several monsoons without interference. But,unavoidably some sites were commissioned before others, and there arecases where modifications had to be made to measures installed beforeand during the first monsoon. However, it is expected that all 21experimental sites will be prepared in readiness for the next rains in June1986.

5.1 Photogrammetric survey

The photogrammetric survey is the principal source of geometricdata. TRRL has let a contract with the City University to take terrestrial

photogrammetric photographs of each experimental site, from whichwill be constructed digital terrain surface models. The models willprovide site contour plans, elevations and profiles.Models for different epochs, subtracted one from another, will be usedto measure for example the distance over which a slope has retreated, orthe volume of material lost. Preliminary measurements indicate that

points can be plotted to within an accuracy of -10 mm over a distance of30 m. The photogrammetric survey is repeated every year, ideallyshortly before and shortly after each monsoon. Negligible movements of

slopes take place during the dry season; therefore two records per yearare adequate.

5.2 Periodic photography

The monsoon is the period of landslide activity, when slides can


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costs will be reported as (a) total labor hours (b) total operating hours foreach item of plant and (c) total material quantities. The maintenanceengineer will then be in a position to balance the likely cost of theremedial measures against the probability of a future landslide event by

applying appropriate local rates to the data and comparing these with thecosts of future maintenance computed in a similar manner.

Documents

Maintenance of Roads in Deserts and Hills