The Mechanism Of The Reduction Of Earth Pressure And Bridge Abutment Displacement With Reinforced Filling Behind The Abutment

The bridge abutment has been built before the soil is filled. The geogrid is laid in soil, and becoming reinforced structure to reduce earth pressure and displacement of abutment. In fact, the displacement, shear strength and friction characteristic of contact surface between soil and geogrid are not yet clearly understood. The research of the basic theory is obviously fall behind engineering practice. Therefore, further researches on shear strength and friction characteristic of contact surface between soil and geogrid are really necessary, the main content of this paper include:1. Based on theoretical studies and experiments of predecessors in reinforced soils, the mechanism of contact surface between soil and geogrid is summarized and analyzed.2. The calculation method of earth pressure is deduced by considering cohesion of soil and displacement of retaining wall, and the rule that the value is calculated by the method is well reflected the value of measure. The method of calculation reflects the characteristic that earth pressure changes with displacement of retaining wall, and at the same time it considers the effect on earth pressure because of the characteristics of filling soil. So this method is applicable and rational.3. The field test is done in the Dong yi-dao s viaduct bridge of Ninghuai expressway (there is no geogrid in the soil filling of the east abutment, but there is geogrid in the soil filling of the west abutment). The equipment to measure earth pressure and displacement of abutment are installed on the east and the west abutment. The data are then analyzed. The results showed that: The value of earth pressure and displacement of the west abutment are smaller than that of the east abutment.4. In order to study shear strength and friction characteristics of contact surface between geogrid and soil in various water content of soils, the direct shear test is done with different normal loads. The results of experiment showed that : For the same value of normal load, there is only minor change of shear strength of contact surface between geogrid and soil when water content of the filling soil is at±3% range of optimum water content, so before-mentioned water content can be used to practice engineering.In summary, the theory of reinforced earth is studied by laboratory test and field test, having certain practical meanings and offering some reference for fill construction in the future.