圆形断面隧道开挖引起的地表及岩土体的位移和变形计算研究

STUDY ON MOVEMENT AND DEFORMATION OF GROUND AND SOIL AND ROCK MASS RESULTED FROM EXCAVATION OF TUNNEL WITH CIRCLE SECTION

隧道开挖必然会对地表环境产生一些影响,使地表产生沉降和水平位移等。基于随机介质理论推导出隧道开挖引起的地表及岩土体移动和变形的一般公式,并对圆形断面隧道开挖进行专门研究,求得一般计算方程。由于该方程在数学上的积分困难,采用在水平方向进行积分,而在深度方向进行若干条分的方法,求得圆形断面隧道开挖引起的地表及岩土体的位移及变形的半解析解,并通过计算机编程实现计算,应用方便。最后根据地表保护分类等级,探讨隧道开挖对周围环境影响的安全评价问题,提出地表变形破坏准则,即当地下开挖引起的地表水平变形大于6mm/m时,可以认为是不安全的。通过工程实例,将理论分析结果和现场实测资料比较,二者较为吻合,说明所提出方法的可靠性,研究成果为减少隧道施工所造成的对地面建筑物和设施的损害提供理论依据并对隧道安全施工有一定的指导意义。

Tunnel excavation will affect the safety of the surroundings, which induces the displacement and deformation of the above ground. Based on the stochastic medium theory, formulas for predicting the displacement and deformation of the ground and rock mass induced by tunnel excavation are deduced, especially for the tunnels with circle section. Because of the difficulty in the integration, semi-analytical solution of prediction of the displacement and deformation of the above ground is obtained through integrating the horizontal direction and dividing many strips along the depth. Furthermore, a program is developed to compute the movement and deformation of the ground and rock mass resulted from excavation of the tunnel with circle section, which is convenient to be applied in the engineering. Finally, according to the classification of the construction protection, the safety estimation of the influence on the surroundings induced by tunnel excavation is discussed and the criterion of ground deformation failure is put forward, namely, it is in danger when the ground horizontal deformation is larger than 6mm/m, otherwise, it is safe. Through an engineering example, the theoretical results and the on-the-spot survey data are consistent, which proves that the computing methods provided are reasonable. The results of the research are significant for tunnel safety construction, and it would be beneficial for the reduction of damage in the constructions and establishments induced by the tunnel excavation.