岩体开挖后受扰动而产生应力重分布过程极其复杂,尤其是在不良地质环境下更甚。对于地质条件差、地应力为高~极高的软弱围岩,其结构受力大小与受力特征对隧道结构安全尤为重要。针对目前研究中存在的问题,结合工程中出现的问题和实际需求,以高地应力软弱围岩条件下的关角隧道、木寨岭隧道等工程为背景,通过地应力现场实测、理论研究与数值分析,对高地应力软岩隧道围岩压力和围岩与支护结构相互作用机制进行研究。主要进行以下几方面的研究工作:(1)在中国地应力场分布规律统计分析基础上,统计得到我国青藏地区平均水平地应力与垂直地应力的比值随深度变化的分布曲线。(2)采用水压致裂法进行兰渝线天池坪隧道和两水隧道地应力现场实测。在此基础上,分析隧道所处的原始高地应力水平及隧道开挖后的地应力分布规律;采用改进的BP神经网络进行了木寨岭、天池坪等隧道的宏观地应力场拓展分析,获得地应力的宏观分布形态与特点。(3)针对现有本构关系,对高地应力软岩尚不具有广泛代表性和卡斯特耐尔公式无法直接计算出在塑性区范围不同发展过程对应的塑性形变压力的问题,以原岩应力和隧道容许位移(或支护后实际量测位移)为出发点,采用岩体软化“直–曲–直”模型,推导了隧道形变压力计算公式。(4)利用台阶法开挖中存在的空间效应和改进的BP人工神经网络模型预测位移以及多项式拟合预测方法,提出两类在高地应力软弱围岩条件下使用开挖应力释放率模型的方法。通过在关角隧道和木寨岭隧道大战沟斜井高地应力软岩地段的应用,探讨其结构荷载与应力释放规律,其结果得到三维数值分析的验证。(5)为验证卡斯特耐尔扩展公式合理性,基于参数全过程变化的应变软化FLAC3D三维数值模型,模拟木寨岭隧道正洞高地应力软岩地段隧道开挖支护过程。三维数值结果与卡斯特耐尔扩展公式计算结果吻合,进一步证明该公式在高地应力软弱围岩条件下应用的可靠性、适用性。在统计青藏地区地应力分布规律基础上,结合现场实测和拓展分析,准确获得高地应力软岩隧道位置原始地应力,为研究围岩压力和围岩与支护结构相互作用机制提供依据。在原始地应力基础上,结合理论分析和数值仿真,获得高地应力软岩隧道的围岩压力计算方法和围岩与支护结构相互作用机制。主要创新点体现以下4个方面:(1)统计分析得到我国青藏地区平均水平地应力与垂直地应力的比值随深度变化的分布曲线。总结出青藏地区地应力分布规律与特点,为判别该区域地应力测试结果的合理性提供依据。(2)针对高地应力条件下软岩隧道大变形问题,引入岩体软化“直–曲–直”模型,推导出适用于高地应力软岩隧道基于原岩应力和隧道位移的隧道形变压力计算公式。(3)提出2种在高地应力软弱围岩条件下使用开挖应力释放率模型的方法。(4)为在三维数值分析中反映软弱围岩参数随坑道变形而不断变化的特性,引入参数全过程变化的应变软化模型,利用FLAC3D软件验证卡斯特耐尔扩展公式应用于高地应力软岩隧道的可靠性和适用性。 The process of stress redistribution caused by the disturbed rock mass after excavation is extremely complicated, especially under unfavorable geological conditions. For the weak geological conditions, the stress is high ~ high soft rock, the structure of the size and force characteristics of the tunnel structure safety is particularly important. In view of the problems existing in the current research, combined with the problems and actual needs in the project, with the projects of Guanjiao tunnel and Muzhailing tunnel under the conditions of high surrounding stress and weak surrounding rock as the background, through field measurement, theoretical study and numerical Analyzes the pressure of surrounding rock and the interaction mechanism between surrounding rock and supporting structure in soft rock tunnel with high geostress. The main work is as follows: (1) Based on the statistical analysis of the geostress field distribution in China, the distribution curve of the ratio of the geostress to the vertical geostress in the Qinghai-Tibet region is obtained through statistics. (2) The field stress field test of Tianchi Ping tunnel and two water tunnels on Lanzhou-Chongqing line was carried out by hydraulic fracturing method. On this basis, the analysis of the original highland stress level in the tunnel and the distribution of ground stress after tunnel excavation; using the improved BP neural network to expand the analysis of macroscopic geostress field of Muzhailing and Tianchiping tunnels, Macro - distribution patterns and characteristics of earth stress. (3) In view of the existing constitutive relation, the problem of plastic deformation pressure corresponding to different development in the plastic zone can not be calculated directly because of the fact that the soft rock with high geostress is not yet widely represented and the Crestale formula can not be directly calculated. Stress and tunnel allowable displacements (or actually measured displacements after support) are taken as starting points. The deformation formula of tunnel deformation pressure is deduced by soft rock mass “straight-curved-straight ” model. (4) Based on the space effect in stepped excavation and BP artificial neural network model to predict displacement and polynomial fitting forecasting method, two methods are proposed to use the model of excavation stress release rate under the condition of high geostress and weak surrounding rock . Through the application of stress and soft rock in the Daosigou trench in Guanjiao tunnel and Muzhailing tunnel, the structural load and stress release rules are discussed. The results are verified by three-dimensional numerical analysis. (5) In order to verify the rationality of Custer extension formula, a three-dimensional strain-softened FLAC3D numerical model based on the whole process of parameters was used to simulate the tunnel excavation and support process of the stress tunnel in the Zhengdong-Dong high stress area of ​​Muzhailing. The results of three-dimensional numerical results are in good agreement with the results of Castel Nile expansion formula, further demonstrating the reliability and applicability of the formula under high surrounding rock stress conditions. Based on the statistical analysis of the stress distribution in Qinghai-Tibet area and the field measurement and extension analysis, the original geostress of the soft rock tunnel with high ground stress can be accurately obtained, which provides the basis for studying the pressure of surrounding rock and the interaction mechanism between surrounding rock and supporting structure. On the basis of the original stress, combined with theoretical analysis and numerical simulation, the calculation method of surrounding rock pressure of soft rock tunnel with high geostress and the interaction mechanism between surrounding rock and supporting structure are obtained. The main innovations reflect the following four aspects: (1) Statistical analysis The distribution curve of the ratio of in-situ stress to vertical stress in Qinghai-Tibet area with depth is obtained through statistical analysis. Summarizes the laws and characteristics of the stress distribution in the Qinghai-Tibet region, and provides the basis for judging the rationality of the in-situ stress test results in this area. (2) Aiming at the large deformation of soft rock tunnel under high ground stress conditions, the softening “straight-curved-straight ” model of rock mass is introduced to derive the tunnel deformation pressure suitable for high ground stress soft rock tunnel based on the original rock stress and tunnel displacement Calculation formula. (3) Two methods for using the model of stress release rate of excavation under high geostress and weak surrounding rock are proposed. (4) In order to reflect the characteristics of the weak surrounding rock parameters changing with the tunnel deformation in the three-dimensional numerical analysis, the strain softening model of the whole process is introduced. The FLAC3D software is used to verify that the Kastell expansion formula is applied to the high-stress rock Tunnel reliability and suitability.