bamboo pile case history inda jian chu

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Chapter 31

The Use of Bamboo and Bakau Piles for SoilImprovements and Application of Pile Raft Systemfor the Construction of Embankment on Peats andSoft Soils

Paulus P. Rahardjo

Professor of Geotechnical Engineering, Parahyangan Catholic University, Bandung,Indonesia

ABSTRACT

Construction of embankment on peats and soft soils has always been faced by the prob-lems of instability and large settlement. The conventional system conducted in practice byIndonesian engineers is the use of bamboo pile raft system (known as “cerucuk”), owingto its availability and low cost. Another aspect to be considered is simple technology.Bakau piles, Ulin and Gelam timber are also used as alternatives to bamboo piles. Whenused under water table, these materials are durable. In the past decade, mini concrete pileraft has emerged to replace bamboo pile raft to carry bigger load and overcome the limi-tation of bamboo or timber piles. Despite the more popular application of this system untilpresent, no method of design and analysis has been established, and approach for calcula-tion are based on experience or simplification. This chapter contains general informationon the occurrence and characteristics of soft soils in Indonesia, ideas and principles on theuse of bamboo, other timber or minipile raft system, method of installation of pile raftunder embankment over soft soils and peats, examples of the use of the system in a num-ber of projects in Indonesia and proposed methods of calculation. Results of full-scaleinvestigation and case histories are used to illustrate the behaviour of single or groupedpiles, to observe the suitability for certain soil condition and to gain an overview of itsapplicability. It has been proven that the system gives advantages to the increase of thebearing capacity of the soft foundation soils and reduce the settlement of the embankment.The system has been successfully applied in many projects and should be further investi-gated. In summary, this chapter gives insight and overview of the use of bamboo or othertimber piles and concrete pile raft system for geotechnical practice.

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1. INTRODUCTION

Many important facilities, infrastructures and even houses are located on soft soils. Inmany cases, the thickness of the soft soil is more than 30 m, that it is not economical toconstruct light structures on concrete or steel piles. Problems with soft soils are stability(during construction) and large deformation or settlement. For such a condition the use ofbamboo or bakau piles gives an alternative for cheap solutions and is very common inIndonesia. They can also be used for temporary support in the event of landslide, speciallyfor shallow sliding plane.

Bamboo or bakau piles are abundant in Indonesia and most South East Asian countries.The practical use of them are many, however very limited research and publications wereseen. The piles vary in size, usually in the order of 70–110 mm in diameter and about3.0–8.0 m long. The most common way for application is either using rows of single pilewith 4 m long driven at a spacing of 40–80 cm or a bundle of 5 or 7 bamboo piles (calledbamboo cluster) of 6.0–8.0 m long with 1.0–2.0 m distance between c/c. For embankmentconstruction, woven bamboo mattress with one or more layers are laid on top of the pilesfor some purposes. The mattress provides sufficient tensile capacity to give additional sta-bility and it separates the fill material from very soft clays or peats. To some extent, themattress reduces differential settlement and distribute the load more uniformly and also itmay give some effect of buoyancy. Spacing of the piles are from 0.30 to 1.50 m depend-ing on the size of each pile or cluster and the need for stability.

Basically, the piles are driven to depth without necessarily reaching stiff or bearing layer.In more developed countries, when piled embankment is designed, the piles are usuallydriven into bearing layer and the main purpose is to carry almost the full load of the embank-ment so that negligible load is to be carried out by the foundation soils. On the other hand,when “cerucuk” is selected, the embankment load is shared to the piles and the foundationsoils through the mattress. Hence the piles are not intended to carry the full load of theembankment. The piles are called “cerucuk” in Indonesia for bamboo piles in group. In somecases, stability is often achieved by the lateral resistance of the pile group and most proba-bly by buoyancy effect of the bamboo piles in the soft soils. Tested samples that were takenafter driving of the piles do not show significant increase in the soil shear strength, but thearea where bamboo piles are driven may have behaved as cluster of soft soil with some kindof reinforcement. A different assumption has been used for design but very little informationabout the real mechanism of the reinforcement effect was clarified. In fact, no standardmethod of design of “cerucuk” has been established and the subject still remain in research.

2. THE OCCURRENCE AND CHARACTERISTICS OF SOFT SOILS IN INDONESIA

Most of the soft soil in Indonesia occurred as alluvial or recent deposit spreading all overthe east coast of Sumatra and north coast of Java where many populated cities are located.

In Kalimantan, the soft soils are found in the east and south of the island, and the rest arealso found in Celebes and West Irian. Figure 1 shows distribution of soft soil in Indonesiaand Southeast Asia. The soils can be distinguished as soft inorganic clay and silt or organicand peat soils. The formation could be from sediment carried by rivers or deposit of veg-etation in low land and humid area.

The majority of soft soils in Indonesia may consist of deposit of Holocene clay. Thismaterial was from the ejecta of volcanoes with a potentially significant content of volcanicash (Barry and Rechlan, 2001). The properties of soft soils in Indonesia are different forthose found on the coastal plains and those inland as a result of fresh water leaching.Younger (1990) and Brenner (1987) also identify that the presence of volcanic derivedsoils give significant effect on the soil properties.

In many cases, the deposit is geologically very young. Cox (1970) provides a relation-ship between deposition rate and degree of consolidation as shown in Figure 2. The aver-age degrees of consolidation for deltaic clays in South East Asia could be from 20 to 100%depending on their location. For sediments in Indonesia for instance, the degree of con-solidation is predicted (from Figure 2) to be 70–80%. This means that the soft clays inmarine environment is underconsolidated.

The Use of Bamboo and Bakau Piles for Soil Improvements and Application 901

Figure 1. The occurrence of soft soil in Indonesia.

For normally consolidated marine clays, the cu/p values have been correlated with plas-ticity index such as suggested by Skempton or Bjerrum (1973), who provide curves foryoung and aged clays. However, when the shear strength of Indonesia soils are plotted tothese curves, it falls below the line which probably relate to the underconsolidation condi-tion. For soft clays in Jakarta, Semarang and Surabaya, some authors (Barry and Rachlan,2001; Rahardjo,1996) suggest that the plasticity indices fall in the range of 50–70%. Thesevalues are related to cu/p ϕ 0.28–0.33 according to Bjerrum, however the factual data formarine soils in Indonesia show that the ratio of cu/p ϕ 0.20–0.24.

3. USE OF BAMBOO AND BAKAU PILES IN INDONESIA

3.1. Use of Timber Piles for Temporary Support of Shallow SlidingMaybe the most common use of bamboo or bakau piles in the beginning was for the tem-porary support of shallow sliding of embankments or natural slopes. Figure 3 gives illus-tration of this application.

The principle of this method is to make use of the perpendicular resistance of the pilesalong the sliding plane and hence it is important that penetration of the piles into potentialsliding plane is sufficient to develop the required resistance. This principle also applies tothe use of soil nailing for a slope stabilization. However, soil nails are stronger and can pen-etrate deeper into the slope not limited by the natural length such as bamboo or bakau piles.The number of piles required to support the sliding mass depend on the depth of sliding

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Figure 2. Relationship between rate of sedimentation and degree of consolidation (Cox 1970).

plane from ground surface and the corresponding area, the angle of slope, the lateral resist-ance of each pile and the residual shear strength of the soil along the sliding plane.

3.2. Pile Raft System for the Construction of Embankment on Peats and Soft SoilsFor many years, bamboo piles with raft have been used by Indonesians in the constructionof embankment on soft soils. The main consideration is for stability reason and in certaincases to reduce the settlement. When the depth of the bearing soil is relatively shallow, thetimber piles maybe driven to reach this layer so that higher resistance may be expected. Thepile can be with have cap or without cap (Figures 4a,b). The use of pile cap is more effec-tive if upper soil layer is sufficiently stiff or a blanket of sand is used under the pile cap. Thecaps will be resting on the stiffer layer so that a portion of the embankment load is carriedby the pile caps. The main disadvantage for timber driven into hard bearing layer is the riskof buckling due to the development of negative skin friction or the fact that the thickness ofthe soft soils shortened to less than the length of the piles due to consolidation settlement.

In most cases the depth of the soft soils is much bigger than the available length of thetimber, and hence the piles are usually spaced at much shorter distance (say 30–50 cm)(Figure 4c). The bamboo piles are generally provided with mattress made of woven bam-boos or geotextile. In this case the main role of the piles and the mattress is to reinforcethe soft soil and form a cluster to support the load of the embankment and to reduce dif-ferential settlement and hence minimize damages of the road pavement and to increase thestability during construction. In practice, this system works very well. The reduction ofsettlement does not significantly depend on the spacing of the bamboo piles and based on


Figure 3. Use of timber piles for temporary support of sliding (Broms and Wong, 1985).

the full scale experimental study in Jakarta, it is reported that compared to untreatedground, the use of bamboo pile raft system reduced settlement of the soft ground to 30%(Rahadian et al., 2000b).

3.3. Bamboo Cluster for Reinforcement of Coastal RevetmentFor coastal revetment to protect high fill reclamation work and sea waves, longer andstronger piles are needed. The common practice in Indonesia is to use cluster of bambooof 3–7 pieces of bamboo tightened together to make a big pile. The raft is also made ofseveral sheets (3–7 layers) to make a strong mattress as shown in Figure 5. This structureis for protection of reclaimed land, north of Jakarta. The typical bamboo cluster is shownin Figure 6.

The main difference between revetment and road embankment is that the load actingon the revetment is not symmetrical. The active earth pressure acting on the landside maycause the structure to move laterally. Other aspects to consider are that the construction isunder water and daily tide level may influence the stability, and hence the embankment fillmaterial is generally of draining type.

3.4. Use of Timber Piles for Embankment on the Bridge ApproachThe construction of a bridge across river on soft soil may pose problem of sliding in the lon-gitudinal direction. The bridge approach is normally elevated and an embankment is con-structed to reach the elevation. It is expected that large settlement and stability will be a bigissue and, the use of bamboo or bakau piles is suitable under the approach (Figure 7).

3.5. Use of Bamboo Piles for Stability of Excavation in Soft ClayFor excavation where sheet pile is used, bamboo piles can be installed behind sheet pilewall or at the bottom of excavation in front of the sheet pile to increase the stability. Bromsand Wong (1985) suggested that the role of the timber piles is to reduce active earth pres-sure (when installed behind the wall) and to increase the passive pressure (when installedin front of the wall), however the real mechanism of this assumption is still unverified and

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Figure 4. The use of timber piles to support embankment on soft soil.

further research is needed. Figure 8 shows the method to estimate reduction of active pres-sure and addition of passive pressure.

The magnitude of active pressure reduction or passive pressure increase should beinfluenced by the length, spacing, and extent of the timber piles installed. Global stabilityneeds to be considered as well.

3.6. Method of ConstructionMethod of installation of bamboo or bakau piles varies depending on the available equip-ment. For a bamboo pile of 4 m long, a backhoe can be used to push the pile into softground. In certain areas where heavy equipment is not available, local drop hammer is


Figure 5. The use of bamboo cluster and raft to support revetment for coastal reclamation.

Figure 6. A cluster of piles consisting of seven bamboos.

common since local technology is made possible. The hammer weight is usually in therange of 300–700 kg. Such a method is illustrated by Figure 9.

Figure 10 explains the sequence of construction of embankments on soft soils withbamboo pile-raft system for a road project in Pelintung, Riau (East Sumatra). In this proj-ect, peats are found all over the area with thickness of 2 m near the coast to about 8 m, 3km away from the coastline. The bamboo pile raft was designed with 6 m and 12 m lengthof bamboo where the longer ones were positioned on the edge of the road and the shorterones were for the middle of the embankment. The bamboo piles were driven and bamboomattress bound in two layers is then laid on the ground surface before spreading the fill

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Figure 7. Tensar reinforced foundation platform over bakau piles–Sungai Serekai–Bridge Abutment–Sarawak(Younger, 1988).

Figure 8. The use of piles for the stability of excavation (Broms and Wong, 1985).

material. The fill placement was followed by compaction as shown on Figure 10f. Thissystem has been successfully applied.

4. MINI CONCRETE PILES AND PILE RAFT SYSTEM FOR EMBANKMENT ON

SOFT SOILS

Instead of the use of bakau and bamboo piles, mini concrete pile may replace them in casewater table is low or permanent structure is required.

4.1. Piles and Geosynthetic for Embankment ConstructionGeosynthetic reinforcement is sometimes required to provide additional stability in theconstruction of embankment on soft soil. However, it can only help stability to a certainlimit. Geosynthetic cannot reduce pore water pressure during fill placement and hence set-tlement is still a big issue. In Europe, it is common to combine pile with cap underneaththe Geosynthetic to carry the load of embankment by the axial capacity of the pile. TheGeosynthetic reinforcement carry part of the embankment load so that the soft soil stressesare reduced (Lawson, 1992) (Figure 11).

4.2. Mini Pile Raft System for Embankment Construction on Soft SoilsSimanjuntak (1997) introduced a similar system of combination of mini concrete pile andpile cap connected to each other. This connection enables tensile forces to be developed


Figure 9. Installation of Bakau Piles with drop hammer (Broms and Wong, 1985).

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Figure 10. The sequence of embankment construction on soft soil with bamboo pile raft system at Pelintung,Riau, East Sumatra. (a) Driving bamboo piles; (b) arrangement of the 1st bamboo raft layer; (c) installation of2nd raft layer; (d) completion of bamboo pile raft (“cerucuk”); (e) placement and spreading of fill material; (f)

fill compaction.

due to the load of embankment. The piles used may have a dimensions of 9 � 9 cm2 to 13� 13 cm2, and the pile cap range from 74 � 74 to 110 � 110 cm2. Basically this systemis similar to the Geosynthetic reinforcement pile embankment described by Lawson,except that the concrete mattress is more rigid and designed to carry partial embankmentload and acting as shallow foundation and hence it is a pile raft system. In this case thebearing capacity of the pile cap is supplementary to the piles. The system was imple-mented for the first time in Jakarta in the year 2000 and research was conducted at BerengBengkel, Kalimantan in the same year (Rahadian and Nurjaman, 2000a).

5. APPROACH FOR ANALYSIS

Problems of constructing embankment on soft soil is governed directly by the shearingresistance of the foundation soils; in other words by the bearing capacity of the soils.Consideration in the stability of embankment on soft soil is most critical during construc-tion. This is due to low permeability of the soft clay which does not allow drainage andconsolidation during loading, so that very little or no shearing resistance of the foundationsoil may be developed. However, after consolidation takes place the resulting shearingresistance in the foundation soil will completely remove the need for reinforcement. Thissituation is explained in Figure 12.

When the bamboo piles are to carry embankment load, the load is transferred through themattress and hence the requirement for pile spacing is governed by the height of the embank-ment, the strength of the foundation soil, rigidity of the mattress and the lengthof pile (hence the axial bearing capacity of the soil). The idea of mini concrete pile andpile raft system is almost similar to piled embankment with Geosynthetic reinforcement. Theprinciple is that the Geosynthetic reinforcement or the raft is required to transferthe embankment loading directly to the piles, thus the soft/foundation soil support negligible


Figure 11. Role of geosynthetic in transferring the vertical embankment loading onto the pile caps (Lawson, 1992).

load. The use of piles as foundation improves stability and reduce settlement. It also enablesembankment to be constructed to any height at an unrestricted rate (Lawson, 1992).Conventionally, the bearing capacity of the pile should be sufficient to carry the weightof the fill above it with an equivalent area of s2, where s is the distance between pile. Figure 13illustrates the method. This approach is too conservative since in practice, the mattress or pilecap also carry the embankment load and acting interactively with the pile.

For global stability a number of approaches are suggested by Broms and Wong (1985),Poulos and Davis (1980), Rahardjo (1996) and others.

5.1. Method Suggested by Poulos and Davis (1980)Poulos and Davis (1980) suggested that the lateral resistance of the pile should be used forstability analysis. Any limit equilibrium analysis such as Bishop method can be used,where additional safety factor is added as summation of the ultimate capacity of the piletimes the moment arm of each pile (Figure 14):

FS �

whereMd is the driving moment, Mr is the resisting moment by the shear strength of the soils

ΔMr � �Hi�ri is the additional resisting moment by the piles.

5.2. Method Suggested by Broms & Wong (1985)Broms and Wong (1985) suggested that the contribution of the pile to the slope stability isdue to axial capacity of pile. The method is basically similar to Poulos and Davis method

�(Mr�ΔMr)��Md

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Figure 12. Influence of reinforcement on stability of embankment on soft soils (Jewell, 1987).


Figure 13. Determination of maximum pile spacing (Lawson, 1992).

Figure 14. Approach for stability analysis based on suggestion by Poulos and Davis (1980).

(1980) except that the piles contribution to the stability are the summation of the axialcapacity instead of the lateral capacity (Figure 15).

The stability at the toe may be analysed by the moment equilibrium equation involvingthe calculation of active earth pressure, the weight of the lower portion of the embankmentand the pile resistance (Figure 16).

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Figure 15. Approach for stability analysis based on suggestion by Broms and Wong (1985).

Figure 16. Stability at the toe of the slope (Broms and Wong, 1985).

5.3. Method Suggested by Rahardjo (1996)Rahardjo (1996) suggested that the inclusion of bamboo piles may be modelled as theimproved ground or a cluster with increased shear strength. For simplicity, the cohesion invertical direction in increased by Pult�s2 and the cohesion in horizontal direction isincreased by Hult�s2, where Pult is the axial bearing capacity of the bamboo pile, Hult the ultimate lateral resistance and s the distance between piles. It has to be understood that Pult

and Hult is dependent on the initial shear strength of the soils and the calculation is valid forundrained condition. For long-term analysis, the effective or drained soil parameters shouldbe used and the increase of shear strength after consolidation is taken into account.

5.4. Finite Element Analysis for Bamboo Pile Raft SystemIt seem that Broms’s approach is more realistic when the tip of the pile reaches bearing stra-tum and negligible lateral movement may occur in the pile. Poulos approach is more reli-able for floating pile. In fact, soil layering and method of construction are also important.Rahardjo approach may be used for conventional analysis as well as finite element method.

Probably the best approach at present time by using finite element modelling or empir-ical method. Rahardjo and Handoko (2004) show the behaviour of timber pile under tankfoundation on soft soil in Samarinda, East Kalimantan. The tank has 9 m height of liquidand the soil condition is very soft clay (known as Delta Mahakam deposit) of 30 m depth.The use of pile foundation will require at least 35 m length of piles and hence cerucuk wasselected with the risk of settlement. The upper soft layer was replaced by 1.5-m-thick com-pacted sand. Since the upper layer is improved with much more stiff soil, significant shearmay result in the pile at the boundary of the soil layer with significantly different moduli.Figures 17 and 18 show the modelling and result of analysis for internal forces (shear andmoment) to the pile. The result of finite element analysis conclude that the previousapproach need to be revised accordingly since the behaviour of the timber pile is differentfor pile in the periphery and the pile in the center. Shear and moment for periphery pilesare 10 times than those for center piles.

6. CASE HISTORIES

6.1. Research on Lateral Capacity of Bamboo PileThe work was conducted at Kalipucang, Banjar, West Java by Brotodihardjo et al. (1991) con-sisting of lateral load test on single pile and grouped piles of bamboo. The soil condition issoft silty clays with average tip resistance of CPT, qc � 5 kg/cm2 through the entire depth ofthe bamboo piles. The water content ranges from 69% to 85% with an average value of 78%.The liquid limit is 77.7–110.2% and plastic limit 38.4–44.4%. Laboratory strength test on thesoil shows the value of c � 3.7–12.5 kPa and φ � 3.5–17°. The vane shear tests on the softclay give a range of undrained shear strength of Su � 2–10 kPa, however for analysis, theresearchers suggested an average value of Su � 3 kPa. Theoretically, the lateral response of


the pile depends on the strength of the soil and the rigidity of the pile. The following data givesthe properties of bamboo from Banjar, West Java:

● Species: Gigantochloa Apus Kurz Bambusaceae● Local name: Bambu Tali, Banjar● Average outside diameter: 7.15 cm

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Figure 17. Modelling of timber pile under tank foundation (Rahardjo and Handoko, 2004).

Figure 18. Typical shear and moment over the length of the bamboo pile in the periphery (Rahardjo andHandoko, 2004).

● Elastic moduli (E): 170.63 kg/cm2

● Tensile strength (σa): 1000–4000 kg/cm2

● Compressive strength (σt): 250–1000 kg/cm2

The location of research work is at the mouth of Kalipucang river in the bank ofCitanduy river surrounded by rice fields. There are a number of tests conducted; howeveronly two selected tests will be reported in this chapter, a single bamboo pile and a groupof seven bamboos. Length of pile embedment is 4.0 m and all bamboos were tested underfree head condition. The test result is shown in Figure 19. A single pile fails under lateralload of 225 kg, while group of seven bamboos reached resistance of 600 kg in the condi-tion of yielding. Further test on the group, resulted in an ultimate group capacity of 900kg. Hence the group efficiency was 0.57.

6.2. Case on the Use of Mini Concrete Pile Raft SystemRahadian and Nurjaman (2000a) reported this system for case at Sentiong River, Jakarta. Inthis project, previously, embankment was supported using concrete sheet pile that failed dur-ing construction. The soft soil is 10 m indepth with average shear strength of 6–10 kPa. Theunderlying layer is medium to stiff clay with various thicknesses. Reconstruction was con-ducted using mini concrete pile raft system, which is driven to 12 m. The concrete mattressconsisted of segmental cap of 74 � 74 cm2 and connected to each other. The piles were posi-tioned under each pile cap. Finite element analysis conducted by Rahadian and Nurjaman(2000a) give a safety factor of 0.46 without the reinforcement and rising to 1.26 by the inclu-sion of mini concrete pile. Figures 20 and 21 illustrate the construction activities.


Lateral load test result

0

100

200

300

400

500

600

700

0 20 40 60 80

Deflection (mm)

Lat

eral

load

(kg

)

1 pile7 piles

Figure 19. Compression of horizontal resistance of single bamboo pile and group of seven bamboos (data fromBrotodihardjo et al., 1991).

6.3. Design and Construction of Embankment on Soft Soils with Bamboo Pile-RaftSystem for Road Project at Pelintung, East SumatraThe project site is located in Pelintung, Sumatera, about 30 km east of Dumai, across theRupat Island, where an industrial site is being developed. Figure 22 shows the location andgeology of the project area. Based on the geological map, the area is described as coastalplain formed during Holocene period. The plain is dominated by soft clay sediment andvegetation forms the peats.

The main goal of the design is to improve the soil for road construction as shown in Figure23. The testing program consists of 4 drilling holes of 30 m depth with SPT and sampling, 3DMTs and 14 CPTs. Based on data from drilling holes, the site may be characterized as softrecent deposits consisting of about 6 m peats underlined by soft silty clays. The void ratio ofpeats are found as high as 3–16 and water content in the range of 250–900%. The void ratioand water content of soft clays are substantially lower than the peats (Figure 24).

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Figure 20. The construction of mini concrete pile raft in Jakarta (JHS Pile Document).

Figure 21. Compaction of fill material over concrete mattress (JHS Pile Document).

As a consequence of the high water content the peats is very compressible as depictedby compression index (Figure 25). The range of Cc is as high as 2–6 while the clay layerhas a much, smaller range of 0.3–1.0. Creep is also an issue to the deformation of the soilsin long term , and hence it is interesting to measure the creep parameter represented by Cα.Owing to the fact that the peat has much higher void than the clay, it is shown that the coef-ficient of consolidation (and hence the permeability) could be 2–30 times higher. It is inter-esting that the value of Cv decreases rapidly by overburden pressure.

Figure 26 shows typical analysis for the embankment on peats and soft soil where thepile raft system is modelled as a cluster with increasing shear strength using Rahardjoapproach (1996). The designed shear strength of the peats is 5 kPa and increased to 13 kPaconsidering the presence of the bamboo piles. The safety factor during constructionreached 1.3 (minimum required � 1.25). Construction method is presented in Figure 10.

7. CONCLUSION SUMMARY

● Many infrastructures are located on soft soils and peats. In certain cases where thethickness of the soft soils is very deep, the use of pile foundation is not economicalspecially for light structure such as road pavement. Bamboo piles provide cheap solu-tion and is reliable to maintain stability and to reduce settlement and differential set-tlement. The risk of long-term settlement can be overcome by nonpermanent pavementsuch as paving block.


Figure 22. Geology of site and location of the project.

● The disadvantage of the bamboo and timber piles is the durability specially if the sys-tem is applied above water table or moisture changes can occur due to ground waterfluctuation. However, once the soft soil is consolidated, the need for reinforcement andstability is replaced by the increase of the shear strength of the foundation soils.

● Mini concrete pile raft system emerges as an alternative for more permanent and heav-ier load and is subject to further research.

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BH-01

CPT-04

CPT-03

CPT-02

CPT-05

CPT-01

CPT-11

DMT-01DDMT-01

4.50

4.50

DMT-02DDMT-03

300

m30

0 m

300

m60

0 m

AA

B

B

Legend :

Drilling / SPT

CPT

MDMT/UNPAR-DDMT

CPT-08CPT-07

CPT-06

CPT-09

CPT-10

CPT-12

CPT-13

CPT-14

BH-03

BH-02

BH-04

DDMT-02DMT-04 DMT-03

5.00

5.00

5.505.50

6.50

6.50

7.50

7.50

6.00

6.00

7.00

7.00

8.00

8.00

Figure 23. Project description and testing programme.

● A number of methods for analysis have been proposed and yet an established oneshould be backed up by more experimental research.

● Some examples have been presented and in summary the paper gives insight on thepractical use of the bamboo and other timber piles for the construction of embankmenton soft soils.


0

5

10

15

20

0 250 500 750 1000

Water content (%)D

epth

(m

)

Dep

th (

m)

PeatsClay

0

5

10

15

20

0 5 10 15 20

Initial void ratio

PeatsClay

Figure 24. Water content and void ratio vs depth (Rahardjo et al., 2004).

0

5

10

15

20

0 2 4 6

Dep

th (m

)

0

5

10

15

20

Dep

th (m

)

Compression Index (Cc)

PeatsClay

Cα

PeatsClay

0 0.1 0.2 0.3

Figure 25. Compression index and values of Cα with depth (Rahardjo et al., 2004).

REFERENCES

Barry, A.J. & Rachlan, A. (2001) Embankment on soft soils in North Java. Embankments on SoftSoils, Proceedings of the Preconference volume, International Conference on In situMeasurement of Soil Properties and Case Histories, Bali, Indonesia.

Bjerrum, L. (1973) Problems of Soil Mechanics and Construction on Soft Clays, Proceedings of the8th International Conference on Soil Mechanics and Foundation Engineering, Moscow.

Bo, M.W., Rahardjo, P.P. & Bawajee, W. (1998) Physical Characteristic of Jakarta Bay Silt,Proceedings of the 13th Southeast Asian Geotechnical Conference, 16–20 November, 1998,Taipei, Taiwan, ROC.

Broms, B.B. & Wong, I.H. (1985) Embankment Piles. Soil Improvement Methods, Proceedings ofthe Third International Geotechnical Seminar, Nanyang Technological Institute, Singapore,27–29 November 1985.

Brotodihardjo, W.Y., Arnaya, W.T. & Sundaya, A. (1991) Penelitian Gaya Horizontal pada PondasiCerucuk Lokasi Daerah Kalipucang, Banjar, Jawa Barat (Research on Lateral Capacity ofBamboo Piles Group at Kalipucang, Banjar, West Java). Pusat Penelitian dan PengembanganPengairan.

Cox, J.B. (1970) The Distribution and Formation of Recent Sediments in South East Asia,Proceedings of the 2nd South East Asia Conference on Soil Engineering, pp. 30–47.

Jewell, R.A. (1982). A Limit Equilibrium Design Method for Reinforced Embankments on SoftFoundations., Proceedings of the 2nd International Conference on Geotextiles, Las Vegas, pp671–676.

Jewell, R.A. (1987) The Mechanics of Reinforced Embankments on Soft Soils, Report No. OUEL1694/87, University of Oxford.

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Figure 26. Example of analysis assuming simplification of shear strength increase in the cluster due to theinclusion of bamboo piles.

Lawson, C.R. (1992) Applied Ground Improvement Techniques, Workshop Applied GroundImprovement Techniques. Southeast Asian Geotechnical Society (SEAGS), Asian Institute ofTechnology, Bangkok, Thailand.

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