Failure Analysis of Strip Foundation on Layered Soil Under Static Loading

Abstract

A soil underneath foundation structure must satisfy design criteria of bearing capacity analysis which is safety against failure and tolerable settlement. Failure analysis of bearing capacity shows differently for a strip foundation on a single layer of soil or layers of soil in a deposit. For a design criterion, the strip foundation on layer deposit can be analyzed easily by using analytical and experimental approaches. Besides, the strip foundation failure behaviour on single soil is also predictable. However, foundation failure on layered soil is difficult to analyze and predict for the complex behaviour of soil underneath the foundation by analytical or experimental method. Thus, a three-dimensional finite element of strip foundation failure is analyzed. The three-dimensional geometry model of layered soils incorporated in the geotechnical finite element of PLAXIS (V8) program with the Mohr-Coulomb soil failure criterion model were chosen in the analysis. The strip foundation bearing capacity on dense sand overlying soft clay with ratio foundation width (B) to the top layer thickness (H) subjected to vertical loading was evaluated. The shear failure mechanism of strip foundation on layered soils was investigated. The numerical analysis results were verified with theoretical analytical formula from published equations. It shows that the ultimate capacity of strip footing bearing on layered soils increase in width of footing (B). The general shear failure mechanism is observed for dense overlying soft clay in all cases except for B/H = 0.5 (B = 2 m) shows local shear failure mechanism.KeywordsShear failureStrip foundationStatic loadingThree-dimensionalFinite element method