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International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.

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  1. 1. As’ad Munawir, Sri Murni Dewi, Agoes Soehardjono, MD, Yulvi Zaika / International Journalof Engineering Research and Applications (IJERA) ISSN: 2248-9622 www.ijera.comVol. 3, Issue 3, May-Jun 2013, pp.150-154150 | P a g eSafety Factor on Slope Modeling with Composite Bamboo PileReinforcementAs’ad Munawir*, Sri Murni Dewi**, Agoes Soehardjono, MD***, YulviZaika*****(Civil Engineering, Brawijaya University, Malang, Indonesia)**(Civil Engineering, Brawijaya University, Malang, Indonesia)***(Civil Engineering, Brawijaya University, Malang, Indonesia)****(Civil Engineering, Brawijaya University, Malang, Indonesia)ABSTRACLandslide phenomenon especially onslopes always become interesting issues to bediscussed. Last few years, composite bamboo pileis one of the innovative slope reinforcementmethods to increase slope stability. Slopemodeling with composite bamboo reinforcementwas using an experiment box with 1,50 m aslength; 1,0 m as width and 1,0 m as height. Itused sand soil with fine gradation and compositebamboo pile with various diameters and spacebetween piles. The load has modeled as a stripfooting with continuous increases load by loadcell until the limit load reached. The problemthat occurred in laboratory has analysed withFinite Element Method. It changed 3D slopemodeling to be 2D modeling. Composite bamboopile has choosen as a new utilization innovationof bamboo to be pile reinforced and a positivevalue to optimize bamboo local material to be asteel reinforced replacement material. The resultof experiment shown that utilizing of pilereinforcement on slope has increased slopestability. It shown with significally increase ofsafety factor, bearing capacity improvement andmaximum limit load that able to reached on slope.Keyword - Bearing capacity improvement,Composite bamboo pile, Finite element method,Slope reinforcement, Slope stability1. INTRODUTIONWhen a shallow footing placed on slopesurface, not only bearing capacity of footing but alsoslope stability will be significally decreased, dependon location of the footing to slope inclination. Forsolve that problem, it is used a reinforced systemwith install the composite bamboo pile. The methodto install pile at the top of slope has a function as aresistant element and at once to resist all lateralforces that work. It work with reduced that lateralforces by transfer of the force to compositebamboo pile reinforcement that installed on somedistance at slope.Some researches has been done toresearched the slope stability with pile reinforcement(De Beer and Wallays, 1970; Ito and Matsui, 1975;Ito et al, 1981; Viggiani, 1981; Ito et al, 1982;Poulos, 1995; Lee et al, 1995; Hong da Han, 1996;Chen et al, 1997; Hassiotis et al, 1997; Ausilio et al,2001; Hull and Poulos, 1999; Cai and Ugai, 2000;Won et al, 2005; Eng Chew Ang, 2005; Lee andWang , 2006; Wei and Cheng , 2009). One of themost important things on evaluating slope stabilitywith pile reinforcement is limit soil pressure whichmobilized on pile-soil interface. There are twosystem analysis on slope stability with pilereinforcement, which are pile stability and slopestability2. SLOPE STABILITY WITH PILEREINFORCEMENT2.1 Bearing Capacity Improvement Analysis(BCI)Bearing capacity improvement factor isfactor that explain the differences of limit loadbefore and after pile reinforcement. The increasingof BCI values shows the increasing of slope stabilityas seen on greater limit load. BCI values can bewrote as equation 1:BCIu=𝑞 𝑢 (𝑅)𝑞 𝑢(1)Where :qu(R) = ultimit bearing capacity with reinforcementqu = ultimit bearing capacity withoutreinforcement2.2 Slope Stability AnalysisThe result from earlier research showed globalsafety factor for slope stability with pilereinforcement estimated from limit equilibrium orfinite element method. Duncan (1990) explained,slope stability with pile reinforcement can adoptedfrom same method for slope stability withoutreinforcement. Ito et al (1979) suggested, slopestability with pile reinforcement analysis to resistshear moment. Safety factor of slope stability withreinforcement can be wrote as equation 2:FSlereng=𝑀 𝑟𝑀 𝑑=𝑀 𝑟𝑠 +𝑀 𝑟𝑝𝑀 𝑑(2)Where :Mr = resistance momenMd = driving momenMrs = resistance momen along critical circle
  2. 2. As’ad Munawir, Sri Murni Dewi, Agoes Soehardjono, MD, Yulvi Zaika / International Journalof Engineering Research and Applications (IJERA) ISSN: 2248-9622 www.ijera.comVol. 3, Issue 3, May-Jun 2013, pp.150-154151 | P a g e𝑴 𝒓𝒑 = additional resistance pile reinforcementmomen2.3 Safety Factor Analysis Using Finite ElementMethodThis research used PLAXIS 8.2 as a finiteelement method program to analize safety factor onslope with non-reinforcement and safety factor onslope with pile reinforcement. PLAXIS 8.2 is used2D modeling which very different with laboratorymodeling that was a 3D modeling. To find the effectfor diameter and space between piles, it cannot enterthe material value directly into initial input. Thequantities of diameter and space between piles mustbe changed into EI and EA form. Furthermore, theyhave to be transformed into equivalent EI form. Theprevious research has been done the plane strainanalysis with equivalenting pile that used in themodeling to sheet pile which has same stiffness toaverage stifness from row of piles and soil, as shownon Fig. 1. Thereby, it can be analyze using thetransformation value between piles and soil to EIequivalen form.Figure 1. EI and EA transformation value betweenpiles and soilPLAXIS modeling in this case, used Mohr-Coloumb method model. Mohr-Coloumb model isvery popular as initial approximation to understandabout general soil behaviour. Parameters on thismodel are; Modulus Young (E), Poison ratio (v),cohession (c), friction angle of soil (φ) and dilatationangle ( ψ ). Table 1 shows the parameters that usedon this model.Table 1. Soil Parameters for PLAXISParameter UnitValueDr74%Dr88%E soil kN/m2311 2427v 0,3 0,3C kN/m20,5 0,5ϕ ° 34,40 38,68𝜓 ° 3,2 7,53. MATERIALS AND METHODS3.1 Box Model and FootingPrime element that used is box, made offiber glass with length : 1,50 m; width : 1,0 m andheight : 1,0 m. Base of box using sheet steel withthickness 1,2 cm. The box made to be rigid enoughfor maintain strain plane condition. Fiberglass usedon box to make observation more easier inlaboratory. The experimental box presented in Fig. 2.Figure 2. Experimental boxReinforcement system consist of hydraulicjack that manually operated with 10 tons capacityand load cell that has been calibrated as a load gaugewhich occured in proving ring reading. A continuousfooting with length 100 cm, width 10 cm and height10 cm located on slope surface that directly linkedwith hydraulic jack. Upper end from hydraulic jacklinked to a rection beam that restraint on steelprimary framework. Load increment process usedstress control that connected with two dial gauges formeasuring footing settlement.3.2 Sand Soil TestSand soil that used in this research is sand soilwith fine gradation. Specific gravity of sand soil’sparticles determined with standart procedure basedon ASTM standart. Mechanical parameters can bedetermined using direct shear test with sample thattook directly from slope experimental model atdesirable density. For determine grain sizedistribution, it is using sieve analysis. The result ofgrain size analysis can be shown on Fig. 3. Physicaland mechanical parameters presented in Table 2.Figure 3. Grain size analysis
  3. 3. As’ad Munawir, Sri Murni Dewi, Agoes Soehardjono, MD, Yulvi Zaika / International Journalof Engineering Research and Applications (IJERA) ISSN: 2248-9622 www.ijera.comVol. 3, Issue 3, May-Jun 2013, pp.150-154152 | P a g eTable 2.Sand Soil CharacteristicsExplanationValueUnitDr74%Dr88%Specific Gravity Gs 2,69 -Dry volumegravityγd 13,2 16,1kN/m3Cohesionc 0,4 0,5kN/m2Friction angle Ф 34,4 38,68 o3.3 Procedure and Experimental ProgramSand soil model compacted every layerwith height 10 cm using standart proctor untilreached the desirable density. After that, it shaped toa slope with desirable inclination angle (50o).Composite bamboo pile reinforcement installed inspecific position. Variables that used are; diameter ofcomposite bamboo pile which symbolized with Dand space between piles that symbolized with D1.Space between center of piles (D1) and pileparameters presented in Fig. 4.(a)(b)Figure 4.(a) Space between piles (D1), (b) Pilesection.This research used composite bamboo piles with 4bamboo sticks as reinforced that installed incomposite piles on circle line as shown in Fig. 5.Figure 5. Bamboo reinforced position in compositepile reinforcementVariation of diameter (D) that used are; 1,27 cm;1,905 cm; 2,54 cm and 3,175 cm. For space betweenpiles (D1), it divided into 4 variations; 7,5 cm; 10cm; 12,5 cm and 15 cm. Whereas for pile location, itused Lx/L ratio with Lx is a distance from sub-slopeto pile location and L is a slope horizontal length.Pile reinforcement variations that used in thisresearch can be shown in Table 3.Table 3. Variables in Slope Model TestNoConstantparametersIndependent variable Exp.1Nonreinforcementb = 0,5 BDr = 74%; 88%-2 H/B = 4D/B=0,127;0,1905;254;0,3175rowLx/L = 0,452D1/B= 0,75; 1; 1,25; 1,5Dr=74%; 88%This experiment produced load and settlement data.From those data, safety factor and BCI value can beproceed as final results.4. RESULT AND DISCUSSION4.1 Effect of Pile Diameter to Safety Factor onSlope with Pile ReinforcementTo find effect of pile diameter to safetyfactor on slope with pile reinforcement, theexperiments must be done using pile reinforcementwith 4 variation of diameters, there are; 1,27 cm;1,905 cm; 2,54 cm and 3,175 cm that located onmiddle of slope (Lx/L = 0,452) with length of pile 40cm. Result of experiment shows that greater pilediameter brings greater BCI and SF as shown on Fig.6,7 and 8.
  4. 4. As’ad Munawir, Sri Murni Dewi, Agoes Soehardjono, MD, Yulvi Zaika / International Journalof Engineering Research and Applications (IJERA) ISSN: 2248-9622 www.ijera.comVol. 3, Issue 3, May-Jun 2013, pp.150-154153 | P a g eFigure 6. Relation between BCI and ratio pilespacing – foundation width with different pilediameterFigure 7. Relation between SF and ratio pile spacing– foundation width with different pile diameter onsecond conditionFigure 8. Relation between SF and ratio pile spacing– foundation width with different pile diameter onfourth condition4.2Effect of Space Between Piles to Safety Factoron Slope with Pile ReinforcementTo find effect of space between piles tosafety factor on slope with pile reinforcement, theexperiments must be done using pile reinforcementwith 4 variation of spaces, there are; 7,5 cm; 10 cm;12,5 cm and 15 cm that located on middle of slope(Lx/L = 0,452) with length of pile 40 cm. Result ofexperiment shows that fewer space between pilesbrings greater BCI and SF as shown on Figure 9,10and 11.Figure 9. Relation between BCI and ratio pilediameter – foundation width with different spacebetween pileFigure 10. Relation between SF and ratio pilediameter – foundation width with different spacebetween pile on second conditionFigure 11. Relation between SF and ratio pilediameter – foundation width with different spacebetween pile on fourth condition1.43751.251.18751.1251.51.3751.31251.251.8751.6251.3751.312521.751.56251.3750.811. 0.50 1.00 1.50 2.00BCID1 / B0,12700,19050,25400,3175KeteranganD / B :1.4351.441.4451.451.4551.461.4651.470 0.5 1 1.5 2SafetyFactor(SF)D1 / B0,1270,19050,2540,3175KeteranganD/B:0.720.7250.730.7350.740.7450.750 0.5 1 1.5 2SafetyFactor(SF)D1 / B0,1270,19050,2540,3175KeteranganD/B:1.43751.51.87521.251.3751.6251.751.18751.31251.3751.56251.1251.251.31251.3750.811. 0.1 0.2 0.3 0.4BCID / B0,751,001,251,50KeteranganD1 / B :1.4351.441.4451.451.4551.461.4651.470 0.1 0.2 0.3 0.4SafetyFactor(SF)D / B0,7511,251,5KeteranganD1/B:0.720.7250.730.7350.740.7450.750 0.1 0.2 0.3 0.4SafetyFactor(SF)D / B0,7511,251,5KeteranganD1/B:
  5. 5. As’ad Munawir, Sri Murni Dewi, Agoes Soehardjono, MD, Yulvi Zaika / International Journalof Engineering Research and Applications (IJERA) ISSN: 2248-9622 www.ijera.comVol. 3, Issue 3, May-Jun 2013, pp.150-154154 | P a g e5. CONCLUSION1. Slope reinforcement with pile reinforcement hasa significant effect to increase safety factor ofslope stability2. On various pile diameter, SF and BCI reachedthe maximum point on 2,54 cm as pile diameter.3. On various space between piles, SF and BCIreached the maximum point on 7,5 cm as spacebetween piles.REFERENCES[1] Eng Chew Ang, “ Numerical Investigationof Load Transfer Mechanism in SlopesReinforced With piles “, Dissertation,Faculty of the Graduate School Universityof Missouri-Columbia, 2005.[2] Gehan E. Abdelrahman, MahmoudS.Abdelbaki dan Youssef G. Yousef,“ Analysis of Stabilizing Slopes UsingVertical Piles “, Eleventh InternationalColloqium on Structural and GeotechnicalEngineering “, Egypt, 2005[3] Ghazi Hassen, Patrick de Buhan,“ Numerical Implementation of aMultiphase Model for the Analysis andDesign of Reinforced Slopes “, First EuroMesiterranean in Advance on Geomaterialand Structure “, Tunisia, 2006.[4] Ito T. dan T. Matsui, “ Methods to EstimateLateral Force Acting on Stabilizing Piles “,Soils and Foundations, Vol. 15, 1975.[5] Ito T. dan T. Matsui dan WP. Hong,“ Design Method for for Stabilizing PilesAgainst Landslide-One Row of Piles ”, Soiland Foundation, Vol. 21, 1981.[6] Jasim M.A. et al.,” Single Pile Simulationand Analysis Subjected to Lateral Load “,EJGE, Vo. 13.,2008.[7] X.P., S.M.H.E. dan C.H. Wang, “ StabilityAnalysis of Slope Reinforced With PilesUsing Limit Analysis Method “, Advancesin Earth Structure Research to Practice,2006.[8] Mostafa A. El Sawwaf, “ Footing Behavioron Pile and Sheet Plie-Stabilized SandSlope “, Alexandria Engineering Journal,Vol. 43, 2004.[9] Mehmet et al.,”Determination of LateralLoads on Slope Stabilizing Piles”,Pamukkale Universitesi MiihendislikBilimreli Dergisi, Sayi,Sayfa,194-202,2009.[10] Osamu Kusakabe et al.” Bearing Capacityof Slope Under Strip Loads on The TopSurfaces”, Soil and Foundation, JapaneseSociety of Soil Mechanics and FoundationEngineering, Vol.21, 1981.[11] Ren-Ping Li, “ Stability Analysis of CuttingSlope Reinforced With Anti-Slidee Piles byFEM “, GeoHunan InternationalConference , 2009.[12] Seyhan Firat, “ Stability Analysis of Pile-Slope System “, Academic Journal, Turkey,Vol. 4, 2009.[13] Toshinori Sakai and Tadatsugu Tanaka,”Finite Element Analysis for Evaluation ofSlope Induced Cutting”, Mei UnivercityJapan and Univercity of Tokyo Japan.[14] Wei W.B. , Y.M. Cheng, “ StrengthReduction Analysis for Slope ReinforcedWith One Row of Piles “, Computer andGeotechnics, 2009.[15] W.R.Azzam et al,” Experimental andnumerical Studies of Sand Slopes Loadedwith Skirted Strip Footing”, EJGE, Vol.15,2010