The Study On Traction Landslide Of Revetment Slope Caused By Plastic Flow Of Soft Soil

Reservoir engineering is an important part in the process of economic development. In recent years, as China’s economic development, the original reservoir has gradually can not meet the needs of industrial and agricultural water and water for the residents, so the existing dams require upgrading. In this paper, combing with an upgrade project of a dam in Nanjing Gaochun, through the analysis of the instability of the soft dam foundationIn this paper, carried out the research of soft plastic flow stability law in dam foundation under the dam loads, it can provide a scientific theory to the dam design in soft soil areas. The main research contents are as follows:(1) The paper analyses the related research at home and abroad of the Undrained shear strength, we can derived undrained shear strength simplified calculation method based on effective consolidation stress method through triaxial consolidated undrained test envelope, then use it to compare with the Mesri method based on Zhejiang Du Lake Reservoir Engineering Investigation data. We can find out that measured values of the effective consolidation stress method is more consistent.(2) Based on the Boussinesq stress solutions at any point in the semi-infinite space under vertical concentrated force and elasticity theory superposition principle, analyze the stress field of soft soil levee foundation, determined shear effect of combined effects by loading and unloading.(3) Combined the stress field under dam loads and the recommended calculation method of the undrained shear strength, introduce Mohr-Coulomb strength failure criterion to determine the calculation method of plastic flow stability. Through the independent preparation of Mathematica analysis procedures to analyse the plastic zone, carried out analysis of depth and scope of the plastic zone, revealing the levee failure mechanism of the traction instability by soft soil plastic flow.(4) Using the method of plastic flow stability analysis to analyse the instability example of a soft dam foundation in Nanjing Gaochun, and comparison with the sliding stability analysis, verified the accuracy of the idea that the reason of the soft dam foundation which can meet the sliding stability requirements still occurs instability is can not meet the requirements of plastic flow stability. Discuss the impact of plastic zone carried out by the factors of excavation near the slop toe and the hard shell layer exists.