不衬砌压力隧洞数值分析中的节理模型

The numerical analysis model of unlined pressure tunnels in jointed rock

本文提出一种有限单元法不衬砌压力隧洞的数值分析,可定量地模拟岩石节理的一系列水力-力学特性,如峰前、峰后的塑性特性,剪胀特性及渗透性等;可以进行固体和流体(岩体和裂隙水流)相互作用的耦合分析;非线性计算中采用的割线刚度法,只要平衡条件满足,可保证在任何情况下(包括应变软化)收敛至正确解答;并通过采用全平面应变模型,避免了平面应变模型的局限性,即隧洞轴线必须平行于一个主地应力方向.本文分析并首次定义了水力剪裂的概念,通过对简化的典型情况的分析,确认了无衬砌压力隧洞的三种基本破坏模式:岩石节理的水力胀裂,水力剪裂和地表上抬.

In this paper a numerical analysis model of unlined pressure tunnels using FEM has been presented. It can simulate quantitatively a series of hydraulic and mechanical characteristics of jointed rock, such as plastic character before and after peak, expansion due to shear and permeability, it can also carry out coupling reaction analysis between solid and liquid. Non-linear computation is implemented by a secant stiffness menthod. Three major failure modes, namely,the hydraulic jacking, hydraulic shearing of joints and uplift of the ground surface, are identified. The concept of hydraulic jacking is first presented.