International Journal of Civil JOURNAL OF CIVIL ENGINEERING(Print),   INTERNATIONAL Engineering and Technology (IJCIET), I...
International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print),ISSN 0976 – 6316(Online) Volu...
International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print),ISSN 0976 – 6316(Online) Volu...
International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print),ISSN 0976 – 6316(Online) Volu...
International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print),ISSN 0976 – 6316(Online) Volu...
International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print),ISSN 0976 – 6316(Online) Volu...
International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print),ISSN 0976 – 6316(Online) Volu...
International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print),ISSN 0976 – 6316(Online) Volu...
International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print),ISSN 0976 – 6316(Online) Volu...
International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print),ISSN 0976 – 6316(Online) Volu...
International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print),ISSN 0976 – 6316(Online) Volu...
International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print),ISSN 0976 – 6316(Online) Volu...
International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print),ISSN 0976 – 6316(Online) Volu...
International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print),ISSN 0976 – 6316(Online) Volu...
International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print),ISSN 0976 – 6316(Online) Volu...
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Numerical modeling of reinforced soil segmental wall under surcharge loading

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  1. 1. International Journal of Civil JOURNAL OF CIVIL ENGINEERING(Print), INTERNATIONAL Engineering and Technology (IJCIET), ISSN 0976 – 6308 AND ISSN 0976 – 6316(Online) Volume 4, Issue 1, January- February (2013), © IAEME TECHNOLOGY (IJCIET)ISSN 0976 – 6308 (Print)ISSN 0976 – 6316(Online)Volume 4, Issue 1, January- February (2013), pp. 01-15 IJCIET© IAEME: www.iaeme.com/ijciet.aspJournal Impact Factor (2012): 3.1861 (Calculated by GISI)www.jifactor.com © IAEME NUMERICAL MODELING OF REINFORCED SOIL SEGMENTAL WALL UNDER SURCHARGE LOADING Machhindra S.Purkar1, Sunil Y. Kute2 K. K. Wagh Institute of Engineering and Research Center, Nashik, Maharashtra, India. 1 Research Scholar 2 Professor and Head of Research Center. Correspondence to: M. S. Purkar, India. E-mail: purkarms@rediffmail.com ABSTRACT This paper outlines the finite element procedure for simulating the performance of a reinforced soil segmental (modular blocks) wall. Analyses were performed using a software code which is developed in FORTRAN and validated for reported case histories in the literature. The material properties of the wall like backfill, foundation, modular concrete fascia blocks and reinforcement were expressed using linear elastic models. A series of parametric studies was conducted to identify effects of reinforcement, stiffness and Poison’s ratio of backfill and foundation strata on the performance of the wall. Increased stiffness of backfill and foundation improves the performance of the wall by restraining the front face deformation. The design charts for deflections at top and bottom and also, height of rotation are developed in the current work by varying the stiffness of backfill and foundation. These charts are useful to the designer to choose appropriate backfill and also, to ascertain the suitability of available foundation for the construction of wall, considering codal provisions regarding deformation limits at the front face of the wall. Key words: reinforced earth wall; finite element analysis; yielding foundation; serviceability criteria; uniform surcharge; segmental wall. 1. INTRODUCTION The reinforced soil structure has gained increasing popularity for replacing the conventional retaining wall. As a result, various procedures have been proposed for designing the said structures [1]. However, the currently used design procedures could only be regarded as semi-empirical. They are mostly based on the limit equilibrium method (LEM) which 1
  2. 2. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print),ISSN 0976 – 6316(Online) Volume 4, Issue 1, January- February (2013), © IAEMEevaluates the internal and external stabilities of the structures at their ultimate strengthcondition. Due to its inability to consider the operational conditions of the structures, such asthe construction sequence, soil structure interaction and load-displacement relationship.LEM-based design has to be encompassed with high factor of safety. The study by Claybournand Wu [2], which evaluated the most commonly used LEM-based design procedures, clearlydemonstrated this fact and it directly reflects our general lack of understanding of theperformance of reinforced soil structures. When compared with LEM, the finite element method (FEM) more powerful analyticaltool for solving the boundary value problems. It renders informations such as the deformationand stress-strain distribution in the structure subject to complex geometries, boundary andloading conditions. These informations are highly required in designing the important civilengineering structures. Also, the design of any structure needs to consider two limit states,the serviceability and ultimate limit state. In case of reinforced soil the serviceability ischecked at working conditions to ensure that, it will retain the characteristics necessary for itto fulfill its function throughout its life without the need for abnormal maintenance. Theultimate limit state relates to all potential collapse mechanisms that can be identified, tomajor damage or deformations in excess of acceptable limits. Also, the behaviour of a reinforced soil retaining structures constructed on a rigidfoundation has been extensively investigated both experimentally and theoretically in pastand many current design criteria’s are based partly on this research [3-19]. However, thebehaviour of these reinforced soil walls constructed on soft or yielding foundations hasreceived limited attention [20-30] and many questions still remain as to the performance andresponse of these structures. The overall behaviour of a reinforced earth wall constructed onyielding foundation, including a review of the vertical stress and displacement at the base ofthe wall, the horizontal stress behind the wall facing and strain pattern in the reinforcement,has not been examined. Hence, the current investigation deals with a short-term analysis of areinforced soil wall constructed on a yielding foundation and analyses the key factorsinfluencing the wall behaviour.2. PARAMETRIC DETAILS The analysis of reinforced earth wall is carried out by considering the differentparameters which are discussed below.2.1 Typical cross section The typical cross section of the earth wall along with the underlying foundation stratais shown in Fig. 1, in which ‘b’ denotes the roadway width, and ‘H’ denotes the wall height.The underlying foundation strata are assumed to be a semi-infinite granular formation. Themodular concrete blocks with reinforcement attached to the blocks are assumed in theinvestigation. A concrete footing protection block was cast at the toe of the wall at the earlystages of construction to prevent the base of the wall from significantly pushing out. 2
  3. 3. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print),ISSN 0976 – 6316(Online) Volume 4, Issue 1, January- February (2013), © IAEMEFig. 1 Typical cross-section of reinforced earth wall resting upon the semi infinite foundation strata2.2 Soil in earth wall Three types of granular (c- φ ) soils are considered for the construction of the earthwall. The engineering properties of these three types of embankment (backfill) material arepresented in Table 1. [31]. Table 1. The engineering properties of the backfill material. Sr. Soil Soil modulus, Poison’s ratio Unit weight, No. designation E (kPa) (m) γ ( KN/m3) 1 E1 1.00E+05 0.300 18.5 2 E2 5.00E+04 0.275 18.0 3 E3 1.00E+04 0.250 17.52.3 Soil in the Foundation Strata Six types of soil are considered in the foundation strata. The engineering properties ofthese six types of soil are presented in Table 2. [31]. Table 2. The engineering properties of the soils constituting foundation strata. Sr. No. Soil Soil modulus, Soil density, γ Poison’s ratio (m) designation E (kPa) 3 ( KN/m ) 1 2 3 4 5 1 F1 1.00E+02 16.5 For each value of ‘E’ 2 F2 1.00E+03 17.0 shown in column-03, three 3 F3 1.00E+04 17.5 values of Poison’s ratio of 4 F4 1.00E+05 18.0 foundation strata namely 5 F5 1.00E+06 18.5 0.30, 0.35, and 0.40 are 6 F6 1.00E+07 19.0 considered. 3
  4. 4. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print),ISSN 0976 – 6316(Online) Volume 4, Issue 1, January- February (2013), © IAEME2.4 Steel reinforcement The reinforcement considered in the analysis is galvanized iron strips of 4 cm wideand sectional area of 1.0 cm2 placed at 50 cm vertical spacing. The elastic properties ofreinforcement assumed in the analysis are: modulus of elasticity (E) 200 GPa, and poison’sratio (m) 0.30. [32-33].2.5 Fascia modular concrete blocks A vertical column of the modular concrete blocks as a fascia element is provided tosupport the reinforced system. The fascia element is 20.0cm thick with a concrete of thegrade M25, hence its material properties are: E=2.5x107 kPa, γ =25 Kn/m3 and µ=0.15 [16].2.5 Surcharge loading (q) A uniform surcharge of magnitude 40 kPa for the considerations to the additionaltraffic road, extending over the full width of roadway is considered in the analysis [34].3. FINITE ELEMENT IDEALIZATION The software developed in FORTRAN for the analysis of reinforced earth retainingwall and tested for reported case histories in the literature is used to conduct the numericalanalysis. The reinforced earth wall with modular fascia concrete blocks was idealized as two-dimensional and a plain-strain FE analysis was performed.From Fig. 1, it is easy to recognize that the system under consideration has a vertical axis ofsymmetry; hence, it is adequate to analyze only half section as shown in Fig. 2. Theboundaries of the section being investigated are based on the following assumptions.i) The boundary defined by the vertical axis of symmetry represents a boundary withhorizontal displacement being restrained.ii) The infinite domain of the foundation strata is curtailed vertically at a depth ‘D’, and theboundary so formed is assumed to be restrained horizontally as well as vertically.iii) The infinite lateral boundary of the foundation strata on the left is curtailed at a distance‘L’, and resulting boundary is assumed to be restrained in horizontal direction.The zone so developed is idealized through square elements of size 0.5m by 0.5m. Thebackfill of earth wall and foundation soil have been discretized using 2D four noddedisoparametric plane strain quadrilateral element. The geometry nodal point locations, loadingand the coordinate system for this element are shown in Fig. 3. Every element is defined byfour nodal points having two degrees of freedom at each node, i.e. translation in X and Ydirections. A unit thickness is assumed for the element. The material properties as a input forthis element, for isotropic elastic case, are soil modulus ‘E’, Poison’s ratio ‘m’ and soildensity ‘ γ ’.The reinforcing elements have been modeled as two-dimensional line element. It is uniaxialtension/compression element with two degrees of freedom at each node (Translation in nodalX and Y directions). No bending of element is considered. The element is defined by twonodal points. The cross sectional area, and material properties (E, m) are the input for thiselement. The displacement direction for the line element is assumed to be linear.The fascia element have the behavior of that of an articulated column, hence it is representedthrough two nodded elements with only axial mode of deformation. In addition for in depthinvestigation between the line elements representing the fascia elements and the adjoiningwall surface, the interface elements are incorporated. As the fascia elements are line elements, 4
  5. 5. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print),ISSN 0976 – 6316(Online) Volume 4, Issue 1, January- February (2013), © IAEMEthe poisons ratio (µ) does not appear in the formation of the element characteristics. Pilot run of theproblems indicate that for a wide range of the interface moduli (Ks, Kn); the response is more or lessunaffected. Hence the following typical values for them are assumed in the current investigations forthe formulations of interface element i.e. Ks=90 kPa and Kn=60 kPa.It was found that, the common approach of providing equally spaced truncated reinforcement withreinforcement length (L) to wall height (H) ratio, L/H equal to 0.7, provides a relatively efficientdistribution of reinforcement force. In contrast, the approach of varying reinforcement spacing in anattempt to mimic the horizontal stress distribution provided to be less efficient and is notrecommended. Varying reinforcement length, i.e. reinforcement extended to the zero force line, didnot provide any significant improvement in force distribution relative to the truncated reinforcementof L/H=0.7. Hence, in the current investigation, the minimum ratio L/H=0.7 is maintained [35-36]. Fig. 2 The details of symmetrical section considered in the analysisFig. 3 Finite element idealization for reinforced wall system with modular concrete fascia blocks 5
  6. 6. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print),ISSN 0976 – 6316(Online) Volume 4, Issue 1, January- February (2013), © IAEME3.1 Details of Idealization Scheme Full information of the idealized system, considered in analysis is presented in Table3. The details of the four material types presented in Table 3 are, backfill material used forthe construction of earth wall, foundation material assumed below the earth wall, the steelreinforcement used as reinforcement in the earth wall and the modular concrete blocks usedto support the fascia of the wall. Table 3. Details of finite element idealization scheme Sr. H( b(m) Number of elements Total Tota Total N m) Backfi Foundati Reinfo Fascia wall no. of l no. no. of o. ll on r- Line Interfa eleme of bound cemen eleme ce nts node ary t nt eleme s nodes nt 1 7. 12.0 180 855 156 15 15 1221 1123 103 54. FINITE ELEMENT ANALYSIS The reinforced earth wall is discretized as discussed in section 3. The parametricinvestigations are carried out by varying the properties (vide Table 1 and Table 2) ofembankment and foundation strata. The response derived for deflected front face profile ofwall for wall height 7.5m and roadway width 12.0m, considering self-weight of wall arepresented in Figs. 4a-i. The modulus of elasticity of reinforcement equal to 200 GPa andsectional area of 1.0cm2 is kept constant for all investigations.The stiffness values of backfill and foundation are expressed in ‘kPa’ as shown in Figs. 4a-i.Each figure shows the variation of front face deflections for a particular value of stiffness(kPa) and Poison’s ratio of embankment and by varying the stiffness of foundation strata toseven types and keeping Poison’s ratio of foundation constant as shown in legend. Theoutward deflections from the vertical line of the wall at the base are plotted as negative valuesand inward deflections at the top are plotted as positive values. 8 Embankment 8 Embankment E=1.00E+05 E=1.00E+05 m=0.30 m=0.30 6 Foundation 6 FoundationHeight of wall, m. Height of wall, m. m=0.30 m=0.35 E=1.00E+02 E=1.00E+02 4 4 E=1.00E+03 E=1.00E+03 E=1.00E+04 E=1.00E+04 2 E=1.00E+05 2 E=1.00E+05 E=1.00E+06 E=1.00E+06 E=1.00E+07 E=1.00E+07 0 0 -5 0 5 -5 0 5 Deflection, mm Deflection, mm (a) (b) 6
  7. 7. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print),ISSN 0976 – 6316(Online) Volume 4, Issue 1, January- February (2013), © IAEME 8 Embankment 8 Embankment E=1.00E+05 E=5.00E+04 m=0.30 m=0.275 6 Foundation 6 FoundationHeight of wall, m. Height of wall, m. m=0.40 m=0.30 E=1.00E+02 E=1.00E+02 4 4 E=1.00E+03 E=1.00E+03 E=1.00E+04 E=1.00E+04 2 E=1.00E+05 2 E=1.00E+05 E=1.00E+06 E=1.00E+06 E=1.00E+07 E=1.00E+07 0 0 -5 0 5 -8 -4 0 4 8 Deflection, mm Deflection, mm (c) (d) 8 Embankment 8 Embankment E=5.00E+04 E=5.00E+04 m=0.275 m=0.275 6 Foundation 6 FoundationHeight of wall, m. m=0.40 Height of wall, m. m=0.35 E=1.00E+02 E=1.00E+02 4 4 E=1.00E+03 E=1.00E+03 E=1.00E+04 E=1.00E+04 2 E=1.00E+05 2 E=1.00E+05 E=1.00E+06 E=1.00E+06 E=1.00E+07 E=1.00E+07 0 0 -8 -4 0 4 8 -8 -4 0 4 8 Deflection, mm Deflection, mm (e) (f) 8 Embankment 8 Embankment E=1.00E+04 E=1.00E+04 m=0.25 m=0.25 Foundation Foundation 6 6Height of wall, m. Height of wall, m. m=0.30 m=0.35 E=1.00E+02 E=1.00E+02 4 4 E=1.00E+03 E=1.00E+03 E=1.00E+04 E=1.00E+04 2 E=1.00E+05 2 E=1.00E+05 E=1.00E+06 E=1.00E+06 E=1.00E+07 E=1.00E+07 0 0 -30 -15 0 15 30 -30 -15 0 15 30 Deflection, mm Deflection, mm (g) (h)Fig. 4 (a-i) Response details of front face deflected profile of earth wall for H=7.5m, b=12m 7
  8. 8. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print),ISSN 0976 – 6316(Online) Volume 4, Issue 1, January- February (2013), © IAEME4.1 Wall resting on weak foundation The results presented in Figs. 4a-i, show that, so long as the foundation stiffnessrepresented by the value of ‘E’ is less than that of backfill (i.e. wall resting on weakfoundation), the vertical face of the wall deflects in a manner which is shown schematicallyin Fig. 5a. The deflected profile as shown in Fig. 5a. is characterized by inward deflection atthe top of the wall and outward deflection at the base; thereby, it has point of rotation overthe wall height. The profile shape is approximately parabolic and if, its theoretical details arerequired, then over the data, the parabolic expression could be fitted by considering the pointof rotation and its location and the amount of deflection at the top and the base of the wall.Hence to define the complete behavior of deflected profile, it needs to define the maximumdeflection at top and base and also the height of rotation. 8 Embankment 8 Embankment E=5.00E+04 E=5.00E+04 Height of wall, m m=0.275 m=0.275 Height of wall, m 6 6 Foundation Foundation m=0.40 m=0.40 4 4 2 2 E=1.00E+03 E=1.00E+07 0 0 -10 -5 0 5 10 -10 -5 0 5 10 Deflection, mm Deflection, mm (a) (b)Fig. 5. Response of wall. (a) resting on weak foundation and (b) resting on strong foundation 4.2 Wall resting on strong foundation In case of the foundation soil having value of stiffness ‘E’ equal to or more than thatof the reinforced backfill (i.e. wall resting on strong foundation), it is observed that, thedeflection at the top is in the inward direction and significant and the deflection at the base isalmost zero. Thereby, it has point of rotation over the wall height. The profile shape isapproximately parabolic. The apex of the parabola defines the maximum outward deflectionsuffered by the wall (Fig. 5b). Hence for strong foundation to check the codal serviceabilityrequirement, the deflections at top, deflection at bulge and its location is necessary. Themaximum deflections at bulge and its location for various wall heights will be reported in thenext paper (part-II).As reported in section 4, the analysis of reinforced earth wall is carried out for self-weight, isalso carried out for a uniform surcharge of 40 kPa extending over a full width of the wall.The front face deflections at top and base and the height of rotation from base in percentageheight are plotted in Figs. 6a-i, for the entire range of three types of embankment and seventypes of foundations. In each Figure the stiffness and Poison’s ratio of embankment is keptconstant. Front face deflections are plotted by varying the stiffness of foundation to six types.First three series shows the variation of front face deflections by varying Poison’s ratio offoundation to 0.30, 0.35 and 0.40 for self-weight of the wall. Next three series shows thevariation of front face deflections by varying the Poison’s ratio of foundation to 0.30, 0.35and 0.40 for a constant surcharge of 40 kPa extended over full width of the wall. 8
  9. 9. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print),ISSN 0976 – 6316(Online) Volume 4, Issue 1, January- February (2013), © IAEME 4 Embankment E=1.0E+05, m=0.30 3 m=0.30,q=0.00 Deflection, mm. m=0.35,q=0.00 2 m=0.40,q=0.00 m=0.30,q=40.0 Kpa 1 m=0.35,q=40.0 Kpa m=0.40,q=40.0 Kpa 0 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07 Foundation stiffness, kPa) (a) 8 Embankment E=5.0E+04, m=0.275 6 m=0.30,q=0.00 Deflection, mm. m=0.35,q=0.00 4 m=0.40,q=0.00 m=0.30,q=40.0 Kpa 2 m=0.35,q=40.0 Kpa m=0.40,q=40.0 Kpa 0 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07 Foundation stiffness, kPa (b) 40 Embankment E=1.0E+04, m=0.25 30 m=0.30,q=0.00 Deflection, mm. m=0.35,q=0.00 20 m=0.40,q=0.00 m=0.30,q=40.0 Kpa 10 m=0.35,q=40.0 Kpa m=0.40,q=40.0 Kpa 0 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07 Foundation stiffness, kPa (c) 9
  10. 10. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print),ISSN 0976 – 6316(Online) Volume 4, Issue 1, January- February (2013), © IAEME 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07 Embankment 0 E=1.0E+05, m=0.30 m=0.30,q=0.00 Deflection, mm. -2 m=0.35,q=0.00 m=0.40,q=0.00 -4 m=0.30,q=40.0 Kpa m=0.35,q=40.0 Kpa m=0.40,q=40.0 Kpa -6 Foundation stiffness, kPa (d) 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07 Embankment 0 E=5.0E+04, m=0.275 m=0.30,q=0.00 Deflection, mm. -2 m=0.35,q=0.00 -4 m=0.40,q=0.00 m=0.30,q=40.0 Kpa -6 m=0.35,q=40.0 Kpa m=0.40,q=40.0 Kpa -8 Foundation stiffness, kPa (e) 20 Embankment E=1.0E+04, m=0.25 10 m=0.30,q=0.00 Deflection, mm. m=0.35,q=0.00 0 m=0.40,q=0.00 m=0.30,q=40.0 Kpa -10 m=0.35,q=40.0 Kpa m=0.40,q=40.0 Kpa -20 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07 Foundation stiffness, kPa (f) 10
  11. 11. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print),ISSN 0976 – 6316(Online) Volume 4, Issue 1, January- February (2013), © IAEME 1 Embankment E=1.0E+05, m=0.30 0.8 m=0.30,q=0.00 Height, (%) 0.6 m=0.35,q=0.00 m=0.40,q=0.00 0.4 m=0.30,q=40.0 Kpa 0.2 m=0.35,q=40.0 Kpa m=0.40,q=40.0 Kpa 0 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07 Foundation stiffness, kPa (g) 1 Embankment E=5.0E+04, m=0.275 0.8 m=0.30,q=0.00 Height, (%) 0.6 m=0.35,q=0.00 m=0.40,q=0.00 0.4 m=0.30,q=40.0 Kpa 0.2 m=0.35,q=40.0 Kpa m=0.40,q=40.0 Kpa 0 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07 Foundation stiffness, kPa (h) 1 Embankment E=1.0E+04, m=0.25 0.8 m=0.30,q=0.00 Height, (%) 0.6 m=0.35,q=0.00 m=0.40,q=0.00 0.4 m=0.30,q=40.0 Kpa 0.2 m=0.35,q=40.0 Kpa m=0.40,q=40.0 Kpa 0 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07 Foundation stiffness, kPa (i)Fig. 6 Response details, (a, b, c) front face deflections at the top, (d, e, f) deflections the base,and (g, h, i) the height of rotation, for H=7.5m and b=12.0m. 11
  12. 12. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print),ISSN 0976 – 6316(Online) Volume 4, Issue 1, January- February (2013), © IAEMEThe observations noted from Figs. 6a-i, show that, the response derived for the 7.50m wallheight and 12.0m road width, for above parametric investigation, with self-weight as well aswith a surcharge of 40.0 kPa remains same. But the magnitudes of inward front facedeflections at top, in case of weak foundation increase by 30% to 40% due to surcharge andfor strong foundation the front face deflections at top are also, inward and they increase 50%to 60%.due to surcharge. The outward front face deflections at base for weak foundationincrease by 30% to 40%.due to surcharge and for strong foundation they tend to zero. Forweak foundation, the front face deflections are sensitive to Poison’s ratio, but for strongfoundation, they are insensitive to Poison’s ratio. The height of rotation which is expressed in terms of percentage wall height is observed tobe almost constant for weak and strong foundation and it varies from 70% to 75% for self-weight of wall and 75% to 85% for a surcharge of 40kPa.11. SUMMARY AND CONCLUSIONS The physical data presented in this paper and the lessons learnt after investigating theresponse of a reinforced soil with segmental wall are of value to researchers engaged indeveloping better understanding of reinforced soil wall behavior. Specific importantconclusions in this regard are summarized below.1. When the wall resting on strong foundation, the rotation of reinforced earth wall is observed at a particular height, imparting inward deflection at the top of wall and outward deflection at the base of wall.2. In case of wall resting on strong foundation also, the rotation of reinforced earth wall is observed at a particular height. But, inward deflection at the top of wall is significant and the deflection at the base of wall tends to zero.3. In case of weak foundation, the response of the wall is sensitive to Poison’s ratio. The front face deflections are changing as the Poison’s ratio increases. But for strong foundation, the response is insensitive to Poison’s ratio.4. Design correlations have been plotted using finite element method for three types of embankments and seven types of foundation strata for different parameters like, deflections at top, deflections at base, height of rotation.. This will help the designer to choose appropriate backfill and also, to ascertain the suitability of foundation for the construction of wall considering codal provisions regarding deformation limits at the front face of the wall.REFERENCES1. B R Christopher and D Leshchinsky. ‘Design of geosynthetically reinforced slopes’. Proceedings of ASCE Geotechnical Engineering Congress, Boulder, 1991, pp. 988-1005.2. A F Claybourn and J T H Wu. ‘Case history comparison of geoynthetic-reinforced soil walls’. Proceedings of Geosynthetic, 91 Conference, 1991, pp. 549-559.3. R J Bathurst, W F Wawrychuk, P M Jarret. ‘Laboratory investigation of two large-scale geogrid reinforced soil walls’. In: Jarret, P. M., McGown, A. (Eds), The application of polymetric reinforcement in soil retaining structures. Kluwer Academic Publishers, Dordrecht, 1988, pp. 71-125. 12
  13. 13. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print),ISSN 0976 – 6316(Online) Volume 4, Issue 1, January- February (2013), © IAEME4. R J Bathurst, D J Benjamin, P M Jarrett ‘.An instrumented geogrid reinforced soil wall’. Twelfth International Conference on Soil Mechanics and Foundation Engineering, Rio de Janeiro, August 1989, Balkema, Rotterdam/ Brookfield, 1989, pp. 1223-1226.5. R J Bathurst and D J Benjamin. ‘Failure of geogrid-reinforced soil wall’. Transportation Research Record 1288, pp. 109-116.6. K Karpurapu and R J Bathurst. ‘Analysis of geosynthetic reinforced soil wall by the finite element method’. Fourth International Conference on Numerical Models in Geomechanics: NUMOG 4, Swansea, U.K., 24-27 August 1992. Balkema, Rotterdam/Brookfield, 1992, pp. 861-870.7. J T H Wu. ‘Measured behaviour of the Denver walls’. International Symposium on Geosynthetic-Reinforced soil walls, Denver, Colrado, USA, 8-9 August 1991. Balkema, Rotterdam/Brookfield, 1992a, pp. 31-428. J T H Wu. ‘Predicting performance of the Denver walls: General Report. International Symposium on Geosynthetic-Reinforced soil walls, Denver, Colorado, USA, 8-9 August 1991. Balkema, Rotterdam/Brookfield, 1992b, pp. 3-20.9. S K P Ho. ‘A numerical investigation in to the behaviour of reinforced soil walls’. Ph. D. Thesis, The University of Western Ontario, Londan, Ontario, Canada, 1993.10. R K Rowe and S K P Ho. ‘A review of the behaviour of reinforced soil walls’. In: Ochiai, H., Hayashi, S., Otani, J. (Eds), Earth Reinforcement. Balkema, Rotterdam/Brookfield, 1993, pp. 801-830.11. R K Rowe and S K P Ho. ‘Some insights into reinforced wall behaviour on finite element analysis’. In: Ochiai, H., Yasufuku, N., Omine, K. (Eds), Earth Reinforcement. Balkema, Rotterdam/Brookfield, 1996, pp. 485-490.12. R J Bathurst and M R Simac. ‘Geosynthetic reinforced segmental retaining wall structures in North America’. Fifth International Conference on Geotextiles, Geomembranes and related products, Singapore, 5-9 September 1994. Southeast Asia Chapter of the International Geotextiles Society, 1994, pp. 1275-1298.13. R L Michalowski. ‘Limit analysis in stability calculations of reinforced soil structures’. Geotextiles and Geomembranes, vol. 16, no. 6, pp. 311-331.14. S M B Helwany, G Reardon, J T H Wu. ‘Effects of backfill on the performance of GRS retaining walls’. Geotextiles and Geomembranes, vol. 17, no. 1, 1999, pp. 1-6.15. A Porbaha, A Zhao, M Kabayashi, T Tishida. ‘Upper bound estimate of scaled reinforced retaining walls’. Geotextiles and Geomembranes, vol. 18, no. 6, 2000, pp. 403-413.16. C S Desai and Khaled E. EI-Hoseiny. ‘Prediction of field behaviour of reinforced soil wall using advanced constitutive model’. J. of Geotech. and Geoenvironmential Engg., vol. 131, no. 6, 2005, pp. 729-739.17. .K Hatami and R J Bathurst. ‘Numerical model to reinforced soil segmental walls under surcharge loading’. J. of Geotech. and Geoenvironmental Engg., vol. 132, no. 6, 2006, pp. 673-684.18. G Q Yang, B Zhang, P Lv, Q Y Zhou. ‘Behaviour of geogrid reinforced soil retaining wall with concrete-rigid facing’. Geotextiles and Geomembranes, vol. 27, 2009, pp. 350- 356.19. J Han and D Leshchinsky. ‘Analysis of back to back mechanically stabilized earth walls’. Geotextiles and Geomembranes, vol. 28, 2010, pp. 262-267.20. J R Bell, R K Barrett, A C Ruckman. ‘Geotextile earth-reinforced retaining wall tests: Glenwood Canyon, Colorado’. Transportation Research Record, PP. 59-69. 13
  14. 14. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print),ISSN 0976 – 6316(Online) Volume 4, Issue 1, January- February (2013), © IAEME21. G R Schmertmann, S H Chew, J K Mitchell. ‘Finite element modeling of reinforced soil wall behaviour’. Department of Civil Engineering, University of California, Berkely, Geotechnical Engineering Report No. UCB/GT/ 89-01, 1989.22. D T Bergado, R Shivashankar, C L Sampaco, M C Alfaro, L R Anderson. ‘Behaviour of a welded wire wall with poor quality, cohesive-friction backfill on soft Bangkok clay: a case study’. Canadian Geotechnical Journal, vol. 28, pp. 860-880.23. D T Bergado, N T L Menil, R Rimoldi, R S Douglas. ‘Performance of full scale embankment on soft Bangkok clay with geogrid reinforcement’. Fifth International Conference on Geotextiles, Geomembranes and related products, Singapore, 5-9 September 1994. Southeast Asia chapter of the International Geotextiles Society, 1994, pp. 1-4.24. N N S Chau. ‘Performance of geosynthetic reinforced soil walls’. Ph.D. Thesis, University of Colorado at Boulder, Colorado, U.S.A., 1992.25. E M Palmeria and L M Monte. ‘The behaviour of model reinforced walls on soft soils. Geosynthetics, 97, Long Beach California, USA, 11-13 March 1997’. Industrial Fabrics Association International, 1997, pp. 73-84.26. J Otani, T Hirai, H Ochiai, S Shinowaki. ‘Evaluation of foundation support for geosynthetic reinforced soil wall on sloping ground’. Sixth International Conference on Geosynthetics, Atlanta, USA, 25-29 March 1998. Industrial Fabrics Association International, 1998, pp. 601-603.27. R K Rowe and G D Skinner. ‘Numerical analysis of geosynthetic reinforced retaining wall constructed on a layered soil foundation’. Geotextiles and Geomembranes, vol. 19, 2001, pp. 387-412.28. D T Bergado, S Youwai, C Teerawattanasuk, P Visudmedanukul. ‘The interaction mechanism and behaviour of hexagonal wire mesh reinforced embankment with silty sand backfill on soft clay’. Computers and Geotechnics, vol. 30, 2003, pp. 517-534.29. R K Rowe and G D Skinner. ‘Design and behaviour of a geosynthetic reinforced retaining wall and bridge abutment on a yielding foundation’. Geotextiles and Geomembranes, 2005, vol. 23, 2005, pp. 234-260.30. D T Bergado, C Teerawattanasuk. ‘2D and 3D numerical simulations of reinforced embankment on soft ground’. Geotextiles and Geomembranes, vol. 26, 2008, pp. 39-55.31. T W Lambe and R V Whitman. ‘Soil Mechanics’. John Wiley, 1969, pp. 353-373.32. R J Bathurst, T M Allen, D L Walters. ‘Reinforcement loads in geosynthetic walls and the case for a new working stress design method (Mercer Lecture)’. Geotextile Geomembrane, vol. 23, no. 4, 2005, pp. 287-322.33. A Bayoumi, A Bobet, J Lee. ‘Pullout capacity of a reinforced soil in drained and undrained condition’. Finite Element in Analysis and Design, vol. 44, 2008, pp. 525-536.34. IRC: 6- (1966). ‘Standard specifications and code of practice for roads and bridges, section II, loads and stresses, Reprint’. 1994, pp. 1-37.35. Swami Saran, K G Gerg, R J Bathurst. ‘Retaining wall with reinforced cohesionless backfill’. J. Geotech. Eng., ASCE, vol. 118, no. 12, 1992, pp. 1869-1889.36. S K Ho and R K Row.’Effect of wall geometry on the behavior of reinforced soil walls’. Geotextile Geomembrane, vol. 14, no. 10, 1996, pp. 521-541.37. V.K.Chakravarth, K.Ramu and M.R.Madhav, “Slope Stability Analysis of Basal Reinforced Embankment under Oblique Pull” International Journal of Civil Engineering & Technology (IJCIET), Volume1, Issue1, 2010, pp. 1 - 14, Published by IAEME 14
  15. 15. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print),ISSN 0976 – 6316(Online) Volume 4, Issue 1, January- February (2013), © IAEME38. S.R.Debbarma and S.Saha, “An Experimental Study on Growth of Time-Dependent Strain in Shape Memory Alloy Reinforced Concrete Beams and Slabs” International Journal of Civil Engineering & Technology (IJCIET), Volume3, Issue2, 2012, pp. 108 - 122, Published by IAEME39. Misam.A and Mangulkar Madhuri.N., “Structural Response of Soft Story-High Rise Buildings under Different Shear Wall Location” International Journal of Civil Engineering & Technology (IJCIET), Volume3, Issue2, 2012, pp. 169 - 180, Published by IAEME40. Wani Ahmad and Javed Ahmad Bhat, “Pre-Tensioned Precast Elements as A Replacement to Wooden Bracings in the Armature Cross Wall System: An Abstract Attempt to Revive the Forgotten Heritage” International Journal of Civil Engineering & Technology (IJCIET), Volume3, Issue2, 2012, pp. 181 - 187, Published by IAEME 15

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