深埋高地应力水工隧洞节理岩体开挖塑性区特征及分布规律研究

Study on the Characteristics and Distribution Laws of Plastic Zone Induced by Deep-buried High-geostress Hydraulic Tunnelling in Jointed Rock Mass

深埋高地应力水工隧洞处于复杂的地质力学环境中,开挖过程中围岩塑性区的分布及演化规律是隧洞稳定控制的关键。为了揭示高地应力水工隧洞开挖塑性区特征及分布规律,文章采用理论分析与数值模拟相结合的方法,推导了塑性区范围的计算公式,并引入新的无量纲参数作为非圆形隧洞围岩塑性区的评价指标,分析了节理岩体在高地应力条件下,侧压力系数以及开挖扰动对围岩塑性区的影响。研究结果表明,开挖扰动对于岩体开挖塑性区发展的轴向影响范围大约为1.0~1.5倍洞径,对于存在节理面的岩体,该影响范围可达到2倍洞径。侧压力系数直接影响围岩的塑性区形状,围岩塑性区有顺着节理面进行不规则扩展的趋势;水平应力与垂直应力差异性越大,节理面对围岩塑性区范围的影响越大,同时节理面有阻止塑性区沿垂直节理面方向扩展的作用。

The deep-buried high-geostress hydraulic tunnel is located in a complicated geomechanical environ⁃ment,and the distribution and evolution laws of plastic zone of surrounding rock during excavation are key to con⁃trolling tunnel stability.In order to reveal the characteristics and distribution laws of plastic zone during excavation of hydraulic tunnels with high-geostress,this paper combines theoretical analysis with numerical simulation,de⁃rives a calculation formula of plastic zone range,introduces a new dimensionless parameter to evaluate the plastic zone of surrounding rock in a non-circular tunnel,and analyzes the influences of lateral pressure coefficient and ex⁃cavation disturbance on the plastic zone of jointed rock mass with high geostress.The study result shows that the axi⁃al development range of rock plastic zone affected by excavation disturbance is about 1.0-1.5 times the tunnel diam⁃eter,while the influence range can be 2 times the tunnel diameter for the rock mass with joint plane.It is concluded that the lateral pressure coefficient directly affects the shape of the plastic zone of the surrounding rock,with the ten⁃dency of irregular development of the rock plastic zone along the joint plane.The greater the difference between the horizontal stress and vertical stress is,the greater the influence range of the joint plane on the plastic zone of the sur⁃rounding rock will be.In addition,the joint plane can prevent the plastic zone from development along the vertical joint plane.