Experimental Study On Static And Dynamic Characteristics Of Clayed Altered Rock In Baige Landslide Area

The geological structure evolution of the southeastern Qinghai-Tibet Plateau is extremely complex.It has experienced multiple periods of strong tectonic magmatism and accompanied by magmatic hydrothermal mineralization and hydrothermal alteration.The above activities have prompted the distribution of a large number of clay-altered rock belts in the Sichuan-Tibet traffic corridor area.The construction of hydropower and railway projects is facing complex engineering geological problems related to clay-altered rocks.The clay altered rock developed in this area has the characteristics of low strength and large deformation,which is easy to produce significant deformation and failure,which should be paid special attention to in engineering activities.In this paper,taking the clay-altered rock developed in Baige landslide area in Sichuan-Tibet traffic corridor as an example,the static and dynamic characteristics of clay-altered rock are studied by using Dynatriax dynamic triaxial test system.The following work is completed :(1)With the help of conventional geotechnical tests,the basic physical and mechanical properties of clay-altered rocks were analyzed,and the development characteristics and distribution of clay-altered rocks were identified.The clay minerals of clay-altered rocks were quantitatively analyzed by XRD diffraction,and the degree of alteration of samples was determined by alteration coefficient.(2)The effects of confining pressure,water content and shear rate on the static characteristics of clayed altered rock were studied by consolidated undrained triaxial shear tests.The stress-strain curve of clay altered rock is mainly strain hardening type.Using the Duncan-Chang model to fit the static elastic modulus,the fitting effect of the model on the strain hardening curve was verified.The effects of water content and shear rate on shear strength and its indexes were analyzed.The strength indexes under different conditions were linearly fitted to obtain the fitting formula of strength indexes.(3)The dynamic triaxial test of clay altered rock under multi-stage loading under stress control was carried out to study the variation of dynamic deformation,dynamic modulus and damping ratio of altered rock under different confining pressures and vibration frequencies.The modified H-D model is used to fit the dynamic modulus curve,and the fitting effect is better.By using data analysis software,the multivariate nonlinear fitting of initial dynamic elastic modulus with confining pressure and vibration frequency is carried out,and the fitting formula is obtained.(4)The dynamic triaxial test of clay altered rock under single-stage loading under stress control is carried out to study the relationship between dynamic strength of altered rock and dynamic stress amplitude,confining pressure and vibration frequency.The critical dynamic stress ratio of clay altered rock under different conditions is obtained by analyzing the experimental data.According to the relationship between the dynamic stress value and the failure vibration times,the dynamic strength curve is drawn,the dynamic strength value and the dynamic shear strength index of the clay altered rock under the specified vibration times are obtained,and the relationship between the dynamic strength index and the vibration times and the vibration frequency is obtained.