Researches On The Roadbed Structure Dynamic Stability

China is an earthquake-prone country, especially in its Midwest. Although the earthquake happened occasionally, if occur, it would lead to catastrophic damage. There is no exception for highway. The roadbed and retaining structure of highway undergo a very complicated process under dynamic load, which has an important impact on its safety. However, few study involved in the property of roadbed soil and dynamic stability under seismic load were carried out in previous researches. Earthquake intensity is the only reference standard in the current earthquake-resistance design criterion till now, the quake frequency and duration are not included, so it can't exactly reflect the character of the roadbed under the earthquake load. In order to solve these problems, the paper did some studies on quasi-static method, large scale shaking table test and finite element method as followings:1. The dynamic stability of the roadbed structure has been improved with quasi-static method. The retaining walls under seismic load of the body were affected by the earthquake. Then the calculation of earth pressure in the retaining wall was taken into account of the impact of the acceleration distribution coefficient. For the roadbed earthquake resistance, the formula was improved by introducing the acceleration distribution coefficient. And the quasi-static method formula for roadbed slope stability was also proposed.2. The method that calculates the residual deformation of roadbed under seismic load was developed. Since the general elastoplastic model can not compute the yield stress point in the plastic deformation plane, the bounding surface elastic-plasticity model was developed based on the Mohr-Column yield function combined with the concept of bounding surface and then the dynamic constitutive model of the roadbed soil was established accordingly. The dynamic triaxial test result was simulated with a self compiled program, and then compared to the ABAQUS calculated result obtained by this model. Consequently, the implementation achievement was proved to be correct.3. A large-scale shaking table model test of roadbed structure with the scale of 1∶20 was introduced. A series of tests were performed with different input seismic wave kinds, amplitudes and frequencies. The dynamic characteristics and dynamic responses of roadbed structure under earthquake, as well as the influence of ground motion parameters were discussed. And also the changes in earth pressure on the retaining wall and the residual deformation of the roadbed slope were studied.4. The dynamic stability of the roadbed structure has been studied with finite element method. Two dynamic numerical simulation models of roadbed slopes were established with ABAQUS program and the validity of simulation was verified by the shaking table model test. The tests were performed with 11 kinds of seismic wave input considering full influence of dynamic intensity of ground motion. Accordingly, the influences of parameters of ground motion on the responses under dynamic loads and the dynamic stability of the roadbed structure were both studied. Moreover, the effect of different amplitude frequency and duration of seismic load on the structure of roadbed was also analyzed.