极高地应力区隧道地质特征及围岩变形机制研究

以某在建高速铁路隧道作为工程实例,结合地质情况,从初始应力、岩体结构和地下水分析了影响围岩的因素。运用理论分析和现场监控量测反馈结果等综合方法,从监控量测数据时态曲线特征、方向性、累计变化量、变形速率、时效性、现场围岩变形情况、隧道施工影响、变形段变形差异性等方面系统分析了极高地应力区隧道围岩变形特征及机制,并得出如下主要结论:1)极高地应力区围岩应力释放有一定的过程,不同的围岩应力释放的速度可能不同,爆破对围岩产生扰动,将一定程度加速围岩应力的释放。2)围岩地质条件不同,变形规律会表现出一定的差异性。3)围岩的变形机制,层状围岩的变形破坏一般形成几个区域:破坏区,崩塌,滑动滑移,张裂、弯曲及折断。4)本隧道围岩变形特征主要是由极高地应力和岩体结构综合决定的,隧道初期支护变形情况一定程度上是隧道围岩变形特征的有效反映。

Geological Characteristics of Tunnels with Extremely High Geostress and Study of Surrounding Rock Deformation Mechanism

The influencing factors on surrounding rock of a high speed railway tunnel under construction are analyzed in terms of initial stress, rock structure and ground water on basis of geological conditions. The characteristics and mechanism of surrounding rocks deformation of tunnel with extremely high geostress are systematically analyzed by comprehensive method of theory analysis and site monitoring feedback in terms of characteristics, directivity, accumulated variation, deformation velocity and timeliness of time dependent curves of monitoring data, site deformation of surrounding rock, tunnel construction influence and deformation difference between two deformation sections. Some conclusions are drawn as follows: 1) The stress release of surrounding rock with extremely high geostress needs time, the stress release velocities of different surrounding rocks are different, and blasting construction will cause disturbance to surrounding rock and speed up the stress release. 2) The deformation laws of surrounding rocks vary as the geological conditions vary. 3) The deformation destruction of layered surrounding rock will form some zones, i.e., destruction zone, collapse, sliding, tension crack, bending and breaking. 4) The deformation characteristics of tunnel surrounding rocks are mainly determined by extremely high geostress and rock structure; and the deformation of tunnel primary support can effectively reflect the deformation characteristics of tunnel surrounding rocks to a certain extent.