Calculation And Analysis Of The Seismic Earth Pressure On Retaining Walls

Retaining wall is a kind of supporting structure to prevent the unstable failure of rock and soil, which is commonly used in civil engineering, hydraulic engineering, traffic engineering and so on. Earthquakes have a great influence on earth pressure of retaining wall. The seismic design of retaining wall has become one of the key topics in geotechnical engineering, so it has an important theoretical and practical significance to study the calculation method of retaining wall seismic earth pressure.Based on the Coulomb theory, Traditional Mononobe-Okabe (hereinafter referred to as the M-O) theory uses pseudo-static method in which the seismic loads are simplified as the inertia forces acting on the sliding wedge, has become the theoretical basis of the seismic design of retaining structures for its simple calculation process and clear mechanics concept. However, a large number of engineering practice and research shows that:the traditional seismic earth pressure have certain limitations for some hypotheses, the calculation results will not able to fully reflect the actual stress state of the retaining wall, and the theory itself has many disputes. Based on the summarizes of previous studies results, this paper carried out research on retaining wall seismic earth pressure computing theory in the following aspects:(1)The granular limit equilibrium equation is used to study the distribution of earth counterforce and the action point of resultant force along the planar rupture surface which is given by the M-O assumption, and the analytical solution of the height of resultant force action point of seismic active earth pressure is given with torque balance method. It makes up the deficiency of M-O theory effectively.(2)Based on the assumption of M-O theory, the method of static equilibrium analysis is used to deduce the generic seismic earth pressure formula, which considers a series of factors including filled soil cohesion, adhesion between soil and wall, uniformly overload on fill surface, surface cracking of cohesive soil, and the analytical solution of critical rupture angle is obtained by graphic method.(3)In light of the deficiency of overall limit equilibrium analysis method by which the earth pressure resultant and its action point cannot given, and considering the effect of retaining wall deflection on earth pressure, the diagonal slice method is used to deduce the strength distribution of seismic cohesive earth pressure under complex states; earth pressure resultant and its action point.(4)Considering the effect of seismic acceleration and the change of time and phase, pseudo-dynamic method is used to achieve the semi-analytic solution of seismic earth pressure of cohesive soil and its distribution. The stability against overturning and sliding based on pseudo-dynamic method is studied.(5)The horizontal level analysis was utilized to deduce the strength distribution of seismic earth pressure; earth pressure resultant and its action point under varied displacement modes. The analytical solution of critical rupture angle is given with graphical method. Then the effects of the retaining wall displacement modes and the reduction coefficient on the seismic earth pressure is analysed.This paper effectively improve the calculation theory of seismic earth pressure, and has a certain reference value on the seismic design of retaining structure.