超大埋深特长公路隧道初始地应力场反演分析

发布时间：2018-04-30 11:11

本文选题：隧道工程 + 初始地应力场　；参考：《中国公路学报》2017年10期

【摘要】：为探明蓝家岩超大埋深特长公路隧道轴线方向的初始地应力场状态,依据工程地质勘察报告,利用有限元计算软件ANSYS建立了工程区三维地质模型;以现场水压致裂法测得的初始地应力资料为研究基础,通过地质力学分析确定影响初始地应力场形成的主要因素,并将其表达为数值计算所需的边界和初始条件;在各影响因素单独作用下,计算得到水压致裂法各测点位置的地应力量值;运用多元回归分析获得了蓝家岩隧道轴线方向上的初始地应力场分布规律。根据蓝家岩隧道轴线处地应力场回归方程,计算得到现场应力解除法各测点位置处的地应力,并与实测结果进行比较,从而验证反演回归计算结果的合理性。结果表明:主应力量值随埋深呈现出近似线性增长的关系,垂直主应力等于或略大于单位面积上覆岩层的自重应力;主应力量值呈现出S_H(最大水平主应力)S_h(最小水平主应力S_V(垂直主应力)的规律,表明蓝家岩隧道初始地应力场以水平构造应力为主导;主应力量值大部分在20 MPa以上,说明蓝家岩隧道为高地应力场隧道;最大水平主应力与最小水平主应力的量值相差较大,根据摩尔-库仑强度理论可知隧道水平面内存在较大剪应力,易导致围岩产生过大变形或破坏;在断层经过区域,受断层挤压剪切作用,地应力变化剧烈,相对断层前后的地层而言有一定的应力松弛。
[Abstract]:In order to investigate the initial in-situ stress field in the direction of the axis of the super-large buried ultra-long highway tunnel in Lanjiayan, a three-dimensional geological model of the engineering area was established by using the finite element calculation software ANSYS, according to the engineering geological survey report. Based on the initial in-situ stress data measured by the in-situ hydraulic fracturing method, the main factors affecting the formation of the initial in-situ stress field are determined by geomechanical analysis, and expressed as the boundary and initial conditions required for numerical calculation. Under the influence of each factor alone, the in-situ stress values of the sites measured by hydraulic fracturing method are calculated, and the distribution law of initial geostress field in the axis direction of Lanjiayan tunnel is obtained by multivariate regression analysis. According to the regression equation of in-situ stress field at the axis of Lanjiayan tunnel, the in-situ stress at each measuring point of the in-situ stress relief method is calculated and compared with the measured result, which verifies the rationality of the inverse regression calculation result. The results show that the principal stress value increases linearly with the buried depth, and the vertical principal stress is equal to or slightly greater than the gravity stress of the overlying strata per unit area. The principal stress value shows the rule of Sch (minimum horizontal principal stress) Sv (vertical principal stress), which indicates that the initial geostress field of Lanjiayan tunnel is dominated by horizontal tectonic stress, and the principal stress value is above 20 MPa. It shows that Lanjiayan tunnel is a tunnel with high ground stress field, and the maximum horizontal principal stress and the minimum horizontal principal stress differ greatly. According to the Mohr Coulomb strength theory, there are large shear stresses in the horizontal plane of the tunnel. It is easy to cause excessive deformation or failure of surrounding rock, and in the area of fault passing through, the ground stress changes sharply by the action of compression and shearing of fault, and there is certain stress relaxation relative to the strata before and after the fault.
【作者单位】：西南交通大学交通隧道工程教育部重点实验室;西南交通大学土木工程学院;
【基金】：国家重点研发计划项目(2016YFC0802201,2016YFC0802202)
【分类号】：U452.11

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