Mechanical Property Of Semi-Infinite Geotechnical Medium And Stability Of Slopes Subjected To Penetration And Explosion Load

As the rock and unsaturated soil are common natural defense materials of the protection engineering, it is essential to study the mechanical property and slope stability of these geotechnical medium subjected to the penetration and explosion load, which is significant for the development of precision-guided weapon warhead and the design of underground defensive project. Based on the continuum theory, this dissertation, setting the military engineering application as the ultimate goal, studied the anti-penetration capacity of the semi-infinite geotechnical medium according to the unified strength theory and analyzed the stability as well as the sliding volume of the geotechnical slope under penetration and explosion load by theoretical inference and MATLAB software. In addition, many factors were considered together in this calculation method, including the strain rate effect, intermediate stress effect, strength criteria, shape and sliding friction of the projectile. The primary work and achievements are as follows:(1) Combining the unified strength theory with a physical model of rock or unsaturated soil, which describes the relationship between dynamic strength and strain rate effect, the rate-dependent dynamic unified strength criteria of rocks as well as unsaturated soils were deduced under the dynamic loading. The rate-dependent dynamic unified strength criteria proposed in this dissertation have comprehensively considered the influence of strain rate effect, intermediate stress effect and strength criteria, and they have included a series of dynamic strength criteria and static strength criteria. Therefore, the proposed criteria herein are a strength criterion series, which are more coincident with the actual situation and applicable to solve problems of complicated stress state.(2) Based on the rate-dependent dynamic unified strength criterion of rocks and the soil disc model, the computing formulae of whole average floating lock stress and strain were deduced with the consideration of impacts of the strain rate effect, intermediate stress effect and strength criteria. According to the physical process of the penetration, a calculating program was developed by using Runge-Kutta method. Furthermore, dynamic responses of the long rod projectile and the target were gained in cases of medium-low speed(V ?900 m/s) projectile penetrating semi-infinite rock targets. The results indicate that the proposed computing method can precisely describe the motion laws of projectiles and the dynamic responses of targets. Through this method, a series of different criteria-based analytic solutions can be gotten and both upper limit and lower limit of the penetration depth can be predicted effectively.(3) For the problem of low speed(V ?300 m/s) projectile penetrating semi-infinite unsaturated soil target, dynamic responses of the long rod projectile and the target were studied by using cylindrical cavity expansion theory and MATLAB software. Moreover, influence characters of such parameters as intermediate stress effect, strength criteria, matric suction, projectile shape and projectile mass were analyzed. The results show that the proposed computing method can predict the penetration depth well and has established quantitative relations for different criteria-based analytic solutions of the saturated soil and unsaturated soil.(4) According to the unified strength theory, quasi-static inertial force method, rigid limiting equilibrium method and Swedish Slipicircle Method, unified expressions of dynamic safety factor for rock slopes and unsaturated slopes were derived under the load of penetration and explosion. Consequently, the loss rate of the safety factor and the maximum slipping volume of the slope were calculated. In additon, influence rules of some parameters were gotten including intermediate stress effect, strength criteria, depth of explosion center and explosive quantity. The results show that the proposed calculating method is suitable to predict both upper limit and lower limit of the dynamic safety factor, the maximum slipping height and the maximum slipping volume.