| The gravity retaining structures depend on the wall tare weight to balance the earth pressure generated at the wall back. They are widely used in slope retaining engineering of general zones, flooded areas and seismic areas. Owning to their advantages of simple forms, easy drawing materials and simple constructions, they are used on a wide scale in the railway engineering.Some hypotheses are adopted in the design and calculation of gravity retaining structures, for example, filling materials of wall back should accord with the Coulomb theory, earth pressure is Coulomb active earth pressure, conversion soil column method is used for train load and its influence on the wall is paralleled to the fracture plane and so on. In ordinary railway, these hypotheses can meet the safety requirements, but with the raising of train speed and the increasing of axle loads, the dynamic effect of train is growing significantly. Especially for the low shoulder and embankment wall,the result derived from Coulomb active earth pressure method,differs from that of the test, which may affects the stability of retaining structures. As a result, it is necessary to have a further study on the changes of load cases of gravity retaining structures with the rising of dynamic loads, and finally achieve a distribution of dynamic earth pressure of retaining structures.In order to study the effection of dynamic stresses on retaining structures, this paper is organized in the following sections:1. Summarize the development and innovation of gravity retaining structures. Moreover, discuss the previous research of gravity retaining structures in statics and dynamics, as well as the general purpose calculation theory currently used at home and abroad. This paper studied the magnitude and distribution of earth pressure of gravity retaining structures at wall back.2. Based on the 1:1 full scale model test of gravity retaining structures, the dynamic earth pressure and its distribution on the back of different types of walls under dynamic loads in different amplitude and at different loading distance are tested and analyzed. By comparing the values calculated with Coulomb Theory and the tested ones on embankment wall and balanced wall, we discuss the difference between theoretical and measured values under different loading distance and loading amplitude.3. With ANSYS finite element model, the numerical simulation values are calculated. In the meantime, a series of instructive conclusions are acquired and compared with theoretical values and measured values. 4. With the systematic and comparative analysis of the numerical simulation values, theoretical values and measured values, the distribution of dynamic stress and the changes of dynamic load under the different loading distance and loading amplitude are obtained. We also address some constructive suggestions to decrease the dynamic earth pressure and strengthen the wall,which can be useful in construction and future research. |
