从施工地质灾害看岩体结构动态控制作用

在我国岩石工程规模加大、趋深而施工扰动范围趋广和趋强的今天，难以避让的不良地质体中常出现的施工地质灾害已成为影响工期和造价的极重要因素。工程实践观测到以不良地质体为主的岩体结构动态变化及其对快速、高强度工程开挖扰动的响应很复杂。理论上需认识不同层次和不同部位岩体变形破坏反映出的结构动态变化和调整，对其控制作用和工程调控需从相互作用时间变化角度加以表述，同时为“短进尺”等地下工程施工经验提供依据。通过总结、回顾岩体结构控制论发展和适用性，结合岩石工程中不良地质体有关的施工地质灾害防治实践，提出基于变形破坏时效性的岩体结构动态控制观(DDC)。以平行于背斜轴部展布的上公山隧洞围岩施工地质灾害导致工期延误和方案多次变更为例，说明岩体结构动态变化是工程施工扰动作用的集中体现和客观结果。本文结果或可为深入研究岩体变形破坏时效性提供一定地质基础。

INSIGHTS OF INNOVATION AND DEVELOPMENT OF ROCK MASS STRUCTURE DYNAMIC CONTROLLING FROCONSTRUCTION- TRIGGERED GEOHAZARD

The deformation-controlling theory of rock mass structure，a basic theory in engineering geology，is critically important for understanding the deformation and failure patterns of rocks. It is also essential for calibration of mechanical parameters and stability evaluation of rock masses. At present，artificial construction- induced disturbance is intense；and the dynamic variations of rock mass discontinuities and the rapidly intensive excavation disturbance associated with engineering performances become extremely complicated. The strength criteria of rock mass need to be considered in combination of rock deformation monitoring. Therefore，the dynamic control and adjustment of the rock mass structure are one of great challenging issues for engineering geologists. Although it is not easy to predict geological defects，we need to know the dynamic variations of geological structures in terms of construction-induced geohazards. Consequently，the controlling effects should be updated with elapsed time. Based on this，the discontinuity dynamic adjusting and controlling opinion(DDC) is put forward，which may be as attributed to the development of rock mass structure controlling theory. For comparison，a case of the Shanggongshan tunnel was employed where dynamic control and adjustment of rock mass during construction were not considered. Various geological defects such as caves and faults along the anticline axis were unexpectedly encountered in construction of this project. Thus，back analysis of the TBM accidents which were time-consuming and caused frequent variations in designs was performed to better understand this issue. This case shows that the dynamic changes in rock mass structure are the results of excavation-induced disturbances. Consequently，counter-measures are to be considered in the framework of the proposed DDC to avoid those unexpected results.