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地下工程施工一般需分步、分段进行,其边界会随着开挖过程不断发生变化。而多数岩石又具有流变特性。因此,隧道施工中围岩力学分析应考虑岩体流变时效与动态施工的共同作用。本文从一般粘弹性时变力学方程出发,用拉普拉斯变换法得出了弹性问题和粘弹性问题间的对应性关系。当把岩石模拟为H-Kilvin粘弹性体,根据对应性关系求得了两向不等压下圆形隧洞任意形式断面开挖过程中的应力和位移积分形式解答。通过折减地应力,也可考虑纵向施工效应影响。当隧洞半径随时间线性变化时,通过某算例分析了断面开挖时不同施工速度、不同角度和侧压系数对位移和应力的影响。结果显示,开挖越缓慢,位移变化也比较平缓,且其施工结束时的位移越大,达到稳定所需的时间越短。
Construction of underground projects generally need to be carried out step by step, the boundary will continue to change as the excavation process. Most rocks, in turn, have rheological properties. Therefore, rock mechanics analysis of surrounding rock should take into account the synergistic effect between rheological aging of rock mass and dynamic construction. In this paper, based on the general viscoelastic time-varying mechanical equations, the corresponding relations between elastic and viscoelastic problems are obtained by Laplace transform. When the rock is modeled as H-Kilvin viscoelastic body, the solution to the integral form of stress and displacement in the excavation of arbitrary section of circular tunnel under two-way unequal pressure is obtained according to the corresponding relationship. By reducing the stress, but also consider the impact of the vertical construction effect. When the radius of the tunnel changes linearly with time, the effects of different construction speed, different angles and lateral pressure coefficients on the displacement and stress at the section excavation are analyzed by an example. The results show that the slower the excavation and the more gradual change of displacement, and the greater the displacement at the end of construction, the shorter the time required to achieve stability.