Effect of Surcharge on Arching Phenomena in Back-to-Back MSE Walls

Back-to-Back walls are the complex geometry of MSE walls and are often used as approach embankments and bridge abutments. Surcharge loads acting on the Back to Back Mechanically Stabilized Earth Wall (BBMSEW) should be applied on BBMSE walls to understand the realistic behavior. In this study, Numerical modeling is performed with Plaxis ۲D to understand the consequence of surcharge on earth pressures, surface settlement profiles of BBMSE walls. A typical ratio of W/H= ۱.۵۵ is taken where a combination of a reinforced and unreinforced zone is present in BBMSEW for analysis and reinforcement stiffness of (J) from ۵۰ to ۵۰۰۰۰ kN/m is used to study the flexibility of the backfill with the reinforcement within. The stress analysis at the transition plane of the reinforced and unreinforced zone showed the arching phenomena. Due to the surcharge, the lateral pressure reduced nearly ۴۲.۳۱% from the Rankine’s active condition and the vertical stresses are very close to the analytical arching equation derived and reduced approximately ۶۳.۵۱% from the overburden pressure after surcharge is applied. It is found that the surface settlement profiles for a particular stiffness (i.e., J=۵۰۰۰۰kN/m) at different wall heights are decreasing from top to bottom. At ۶m height for J=۵۰kN/m, it is observed that the settlements have occurred in the reinforced zone whereas for the J=۵۰,۰۰۰kN/m the settlements were observed only in the unreinforced zone. From the analysis, it is concluded that arching is predominant in the transition zone of BBMSEW and must be considered for the estimation of earth pressure and design of BBMSEW.

Keywords:

Surcharge load , vertical stress , Arching , Numerical model , Back-to-back walls , Surface Settlement profile