Limit Equilibrium Analyses for Internal Design of Geosynthetic Reinforced Slopes: Influence of Potential Failure Surface
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ORIGINAL PAPER
Limit Equilibrium Analyses for Internal Design of Geosynthetic Reinforced Slopes: Influence of Potential Failure Surface and Strength Distribution Castorina Silva Vieira • Maria de Lurdes Lopes Laura M. Caldeira
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Received: 3 July 2012 / Accepted: 12 March 2013 / Published online: 20 March 2013 Ó Springer Science+Business Media Dordrecht 2013
Abstract The paper presents results from a computer code, based on limit equilibrium analyses, able to quantify earth pressure coefficients for the internal design of geosynthetic reinforced soil structures and identify the potential failure surfaces. Failure mechanisms assuming bilinear or logarithmic spiral failure surfaces are considered. The influence of the potential failure surface and geosynthetic strength distribution on the earth pressure coefficient is analysed. Required reinforcement tensile strengths calculated by the developed program are compared with values published in the literature. To further evaluate the capabilities of limit equilibrium analyses, the numerical modelling of a geosynthetic reinforced steep slope, designed at ultimate limit state conditions (FS = 1), is also presented. Good agreement was achieved between the potential failure surfaces predicted by limit equilibrium analyses and those obtained with numerical modelling.
C. S. Vieira (&) M. L. Lopes Faculty of Engineering, University of Porto, R. Dr. Roberto Frias, 4200-465 Porto, Portugal e-mail: [email protected] M. L. Lopes e-mail: [email protected] L. M. Caldeira National Laboratory of Civil Engineering, Av. do Brasil, 1700-066 Lisbon, Portugal e-mail: [email protected]
Keywords Geosynthetic reinforced structures Limit equilibrium analysis Internal stability Numerical analysis List of Symbols FS Factor of safety (dimensionless) H Height of structure (m) H Horizontal component of inter-wedge force (Fig. 1 and Eq. (1)) (kN) Kreq Equivalent earth pressure coefficient (dimensionless) uniform Equivalent earth pressure coefficient for Kreq uniform distribution of reinforcement (dimensionless) N Resultant force of normal stresses over the failure surface (kN) Pa Required force for equilibrium (kPa) r Radius of log spiral surface (m) S Resultant force of shear stresses over the failure surface (kN) Sv,i Contributory height for the ith layer (m) Ti Required strength for reinforcement layer, i (kN/m) Tmax Maximum reinforcement tensile force (kN/m) V Vertical component of inter-wedge force (kN) W Weight of failure mass (kN) XC Horizontal coordinate of the centre of gravity (failure mass) (m) XP Horizontal coordinate of the pole (m)
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Ya YC YP
Geotech Geol Eng (2013) 31:1123–1135
Elevation of Pa application point (above the base) (m) Vertical coordinate of the centre of gravity (failure mass) (m) Vertical coordinate of the pole (m)
Greek Letters b Slope angle (°) d Friction angle between the soil and the wall facing (8) esmax Maximum soil shear strain (dimensionless) / Soil internal friction angle (°) /d Design value of internal friction angle of backfill (°) c Backfil
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