Failure of Saturated Silty Loam Deposit Subjected to Cyclic Shear

On the basis of the liquefaction test results, failure of a saturated silty loam deposit during earthquakes is investigated theoretically. First, from the liquefaction test results, it is shown that the silty loam failed when the pore water pressure ratio reached 0.4 to 0.8 by cyclic shear stress, and its failure was essentially similar to liquefaction of sands. Second the changes of the pore water pressure induced in the deposit by the ground motions (the El Centro earthquake (1940) and the simulated earthquake) are calculated by use of the seismic response analysis, and the change of pore water pressure obtained from the test. Analytical results show the relationship between the ratio of the amplitude of the equivalent sinusoidal acceleration to that of the earthquake accelerations which are required to cause the failure of the deposit, and equivalent number of cycles.