隧道开挖的围岩损伤扰动带分析

在给出隧道开挖损伤扰动带的概念、主要影响因素基础上,提出了隧道开挖损伤扰动带的力学、渗流特征及表征方法。在现场实测基础上,利用数值法研究了隧道开挖后的不同开挖方法的变形、渗流场变化规律。结果表明:开挖损伤主要决定于隧道开挖方法;隧道开挖引起的渗流影响边界大于力学影响边界。研究结果有助于合理地建立隧道开挖问题的流固耦合模型。

STUDY ON MECHANICAL AND HYDRAULIC BEHAVIOR OF TUNNEL SURROUNDING ROCK MASSES IN EXCAVATION-DISTURBED ZONE

The damage of tunnel surrounding rock masses usually results from the redistribution of stress in disturbed rock mass in tunnel excavation process. The excavation-disturbed zone (EDZ) is defined as the rock zone where the rock properties and conditions,such as fracture,stress and hydraulic aperture,have been changed due to the processes induced by excavation. EDZ is considered to be physically less stable and can form a continuous and highly permeable pathway of groundwater flow. The characterization of EDZ will affect tunnel support structure design,tunnel construction and tunnel surrounding rock mass stability analysis. Seismic survey techniques can be used to examine the nature of EDZ around the tunnel. Based on the concept of EDZ and the primary factors that lead to the change of rock properties,a methodology is proposed to depict mechanical and hydraulic behavior of EDZ. By using the in-situ data,deformability and hydraulic properties are studied by numerical analysis. The results show that the excavation damage depends on the excavation method. In addition, the influence boundary of the excavation-disturbed stress zone is smaller than that of the seepage. Therefore,the seepage boundary condition should be emphasized in establishing the coupled fluid-solid numerical models. The results will make the establishment of coupled fluid-solid model more reasonable.