an investigation on lateral earth pressure in integral bridges due to the cyclic loading

several relationships to assess at-rest pressure coefficient in retaining walls, have been developed by different researchers. these suggested relationships are generally a function of mechanical soil parameters such as internal friction angel, poison ratio and over-consolidation ratio. in integral bridges, however, this coefficient is also a function of many other parameters other than soil characteristics. the deck of this type of bridges is subjected to the horizontal movement, which results in cyclic load to be applied to the bridged wall. in the present research, the influence of this cyclic loading on the lateral earth pressure is investigated. a prototype laboratory model of a retaining wall, with cohesionless backfill, was developed in which different cycles of lateral displacement with various amplitudes were applied to the wall. the model was instrumented by small pressure cells to measure the earth pressure at-rest, active and passive conditions. additionally, the applied load and displacement to the wall were measured, using load cell and lvdt.the results of this study indicate that the variation of at-rest earth pressure coefficient with depth is not linear and it is not only a function of internal friction angel but dependent to the depth and number of cycles. finally, it could be concluded the cyclic loading causes the backfill material becomes stiffer and stiffer so that an arching is formed. this results in a reduction in lateral earth pressure in the lower parts of the wall.