| Landslides are a common geological disaster that causes widespread damage to socioeconomic development,human life,and property.The implementation area of the "Western Development" and "Belt and Road Initiatives" for our country closely coincides with the area prone to landslide geological disasters.Slope stability analysis and reinforcement have always been important research topics in geotechnical engineering due to the complexity and severity of landslide disasters.It is a critical step in determining a reasonable value for the slip surface shear strength parameters in landslide stability evaluation and prevention engineering design.By examining the "randomness and uncertainty" and "nonlinearity" of rock and soil shear strength parameters,as well as the actual "three-dimensional shape" and "failure mechanism" of complex landslides,the main research contents and results of this dissertation are as follows:(1)In view of the different failure modes,taking overall sliding landslides,progressive landslides,and bedding landslides as examples,combined with the failure characteristics of specific engineering examples,the corresponding stability analysis model is constructed.Considering the randomness of shear strength parameters,a new method for the reliability back analysis method of the shear strength parameters is proposed by solving the maximum probability combination value of shear strength parameters corresponding to the minimum reliability index.The randomness and uncertainty in slope engineering can be considered,and the engineering problem of determining multiple shear strength parameters based on a single landslide section can be solved.(2)Considering the three-dimensional geometric characteristics of the actual landslide,a reliability back analysis method of three-dimensional landslide shear strength parameters is proposed based on the upper bound limit analysis method.Bayesian theory is introduced to update prior information using field experimental data,and a more reasonable irregular sliding surface generation method is used to simulate the real irregular three-dimensional shape of the sliding surface,which can more accurately grasp the parameters information,carry out finer bar column division,and obtain more reasonable inversion results.It addresses the issue that the traditional two-dimensional parameter back analysis method does not take lateral constraints and three-dimensional spatial characteristics of landslides into account.(3)The reliability back analysis method of nonlinear Mohr-Coulomb shear strength parameters of two and three-dimensional soil landslide is established based on the real nonlinear characteristics of soil strength parameters.The difference of back analysis between linear Mohr-Coulomb failure criterion and nonlinear Mohr-Coulomb failure criterion is compared and analyzed.It demonstrates that the landslide’s anti-sliding force is affected by the stress level on the actual sliding surface,and the nonlinear characteristics of rock and soil strength cannot be ignored.The problem of determining the values of nonlinear shear strength parameters of soil landslide has been solved.(4)Considering the nonlinear characteristics of rock mass material and structural plane strength parameters,the stability analysis methods of two-dimensional and three-dimensional slope are built.The initial value range of nonlinear strength parameters is determined using the field test,photogrammetry and engineering analogy,and the reliability back analysis method of nonlinear strength parameters of rock landslide is proposed.For engineering practice,a simple and practical method for determining the nonlinear shear strength parameters of rock landslides is provided.(5)The slope reliability reinforcement design method with anchor cable is proposed based on the reliability back analysis theory of nonlinear shear strength parameters of landslides.It is discovered that as parameter variability improves,the depth of the sliding surface increases,as does the anchoring force required to achieve the target reliability index.It can provide a theoretical basis for the application of reliability back analysis method of shear strength parameters and reliability reinforcement theory in landslide treatment design.This dissertation has 105 figures,45 tables and 341 references. |
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