Study On Macroscopic Parameters And Strain Softening Constitutive Properties Of Slope Mud Means

The weak intercalation is one of the key factors of bedding slope instability. Specially, mudded intercalation—as one of the most common secondary type of weak intercalations—as a extremely low shear strength and as a result, it usually turns out be the control-factors of landslides. The key issue of mudded intercalation is about its strength,however, there has been a common problems appeared in the application of actual project which is that the mudded intercalation is always too thin to obtain the strength parameters exactly by direct shear tests or triaxial compression tests. In order to solve this actual problem, the paper attempts to start the research from the mesoscopic scanning of mudded intercalation micro-structure. Combined with the uniaxial compression test and digital speckle measurement technology, the deformation laws and failure characteristics under the uniaxial compression are acquired. Finally, the discrete element method is adopted to establish the numerical model of mudded intercalation and predict its strength by studying the strain softening constitutive characteristics, Specific research contents are as follows:(1) we have got the mudded intercalation mesoscopic structure message first by scanning electron microscopy. Then the binarization processing of scanning image we was carried out which is combined with threshold segmentation technique. Finally,by using matlab statistical analysis, we quantified the mesoscopic structure and mainly obtained the mudded intercalation porosity for the subsequent discrete element modeling.(2) By using digital speckle imaging techniques,we have monitored and recorded the deformation and failure of the mudded intercalation during the uniaxial compression test;By using strain failure criteria and limit equilibrium condition in soil mechanics,we have research and got the shear strength characteristics of the mudded intercalation.(3) We have established a discrete element model of the mudded intercalation by using PFC particle flow programming language, analyzed the parameter sensitivity in numerical uniaxial compression test and direct shear tests,mainly studied a number of factors affect sample stress-strain constitutive relation,such as particle contact stiffness, friction coefficient between particles, bond strength, vertical stress and loading rate, and so on.Combined with the result of the indoor uniaxial compression test,we calibrated the mesoscopic mechanics parameters in discrete element model of the mudded intercalation.Finally,we got a numerical model that could reflect the real state and mechanical properties of the mudded intercalation.(4) We have researched the shear damage mesoscopic mechanism and characteristics of strain softening on the mudded intercalation by using numerical direct shear tests and repeated shear test.Predicted the peak and residual strength of the mudded intercalation.With the advance of western development and a large number of highways being built in western mountainous areas, problems about embankment slope stability that caused by mudded intercalation have become increasingly prominent. This thesis aims to provide a basis for parameter in slope stability evaluation in practical engineering.