Analysis of Soil Stiffness Variation in Case of Cavity Generation in Underground below Subway Track using Light Weight Deflectometer

Cavities have been found many times recently in downtown of metropolitan area due to old and damaged utility pipes installed in the ground long time ago. The cavities are generated by spilling out of flowing water from the pipes mostly. The cavities generated below subway track can induce irregularities and unstabilities to the track. In this study, a finite element program ABAQUS is used to analyze stress and deflection spectrum in order to get soil modulus by simulating LWD test applied to the ground with cavity. It is found from the FE analysis of LWD test that the LWD test can be used effectively to check out cavity existence below subway track by checking modulus variation of the ground.