Deformation control law of rock fatigue failure,real-time X-ray CT scan of geotechnical testing,and new method of stability analysis of slopes and dam foundations

Some progresses were presented on the field of rock and soil mechanics for the past few years.Firstly,the test results of rock fatigue failure were discussed.A lot of tests have shown that the strain of fatigue failure is controlled by the whole stress-strain process curve.The testing techniques and the characteristics of the new testing machine for rock mechanics,RMT were introduced.The post-failure curves of type I and type II for rock were reviewed.More emphasis should be paid on the deformations in rock strength theory research based on the rock fatigue failure tests.Secondly,the creative testing technique in rock and soil mechanics experiments,the X-ray computerized tomography(CT) real-time scan was presented.The testing principles and methods were given.The triaxial testing results of Nanqiao sandstone were discussed.The whole stress-strain process curve of Nanqiao sandstone was obtained,and comparison between the former and the typical whole process curve was analyzed.A new approach was provided for rock and soil mechanics,and it connected the macro-mechanical properties of rock materials with the meso-structures including the compression and growth of microcracks,bifurcation,and crack fracture.Thirdly,the vector sum method of stability analysis for dam foundation and slope was given.The safety factor by the vector sum method was defined based on the vector characteristics of the forces.The significance of the vector sum method safety factor was clear in physics.The calculating process was simple,and it facilitated the application of this analysis method in engineering.The 2D slope calculation models with fixed circle slip surface,non-circle slip surface and curved slip surface were discussed.The results indicate that the safety factor obtained by vector sum method is in good agreement with the safety factors obtained by the limit equilibrium method.It is shown that the new method is more stable.The calculation formula of safety factor for the 3D problem by vectors sum method is also given.