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由于在许多实际条件下,比如节理岩体中,线性的M-C准则不太适用,非线性的Hoek-Brown比较适用,因此,可以尝试使用这一非线性屈服准则对洞室变形进行研究。研究隧洞变形时,将围岩分为弹性区、应变软化区、塑性流动区。采用Hoek-Brown准则和非关联流动法则对洞室变形进行了理论推导;软化区域围岩参数随着塑性变形增加而变化,解析法难以求得应力,采用龙格-库塔方法进行数值计算,求解得到塑性软化区和流动区半径,并最终求得洞室变形。通过算例计算表明,在不考虑软化区和流动区时,方法和Carranza-Torres计算结果相差甚小;随着原岩应力的增加,膨胀角对洞室变形的影响增大。
Since the linear M-C criterion is not suitable for many practical conditions, such as jointed rock mass, and the nonlinear Hoek-Brown method is suitable, we can try to study the deformation of the cavern using this nonlinear yield criterion. When studying tunnel deformation, the surrounding rock is divided into elastic zone, strain softening zone and plastic flow zone. The Hoek-Brown criterion and the non-associated flow rule are used to deduce the deformation of caverns. The surrounding rock parameters in the softened zone change with the increase of plastic deformation. It is difficult to obtain the stress by analytic method. The Runge-Kutta method is used for numerical calculation. Calculate the radius of the plastic softening zone and the flow zone, and finally determine the deformation of the cavern. The calculated results show that there is little difference between the method and Carranza-Torres method when the softening zone and the flow zone are not considered. With the increase of the original rock stress, the influence of the expansion angle on the deformation of the cavern increases.