【作者】 石磊；

【导师】 张明；

【作者基本信息】 清华大学 ， 水利工程， 2019， 硕士

【摘要】 城市特长输水工程通过跨地调水,解决城市居民生活用水和城市工业用水,保障农业粮食生产,缓解城市地下水开采压力,为生态环境保护提供支持。本文以吉林省中部城市输水工程为背景,在输水干线施工方案中,选择6个典型断面作为研究对象,利用Abaqus有限元软件进行二维数值建模,分析钻爆法和TBM两种施工方法下围岩稳定性和衬砌结构设计,通过调整衬砌厚度和复合衬砌荷载分配的方法,进行衬砌优化设计。主要成果如下:⑴对比分析钻爆法和TBM对隧洞开挖后的围岩稳定性影响,对钻爆法开挖断面设置围岩物理力学参数折减区,模拟钻爆法施工对围岩的损伤。钻爆法开挖的断面中,围岩主应力值在围岩扰动区和相邻未受影响区域是不连续的,由于隧洞开挖导致围岩扰动区岩体刚度减小,使其最小主应力比相邻未受影响区域更大。⑵隧洞开挖后,围岩平面最大主应力和最小主应力均为负值,说明围岩单元均处于受压状态,符合岩石抗压强度大于抗拉强度的力学特性;计算围岩安全系数F_s值,部分断面存在安全系数小于1的情况。⑶一衬加载后,一衬单元切向应力均为负值,围岩径向位移均指向洞周内部,能充分发挥衬砌材料力学特性;部分断面存在围岩单元安全系数小于1的情况,应进行复合衬砌优化设计。二衬加载后的通水工况,由于内水压力的作用,一衬切向压应力减小,各断面围岩安全系数均提高,说明通水工况有助于围岩和衬砌稳定性。⑷增加一衬厚度,在施工工况和通水工况下,衬砌切向应力有所减小,围岩安全系数有不同程度的增长;相同复合衬砌优化方案下,不同断面的衬砌切向应力减小速率不同。通水工况下,一衬厚度与一、二衬切向应力平均值呈线性关系。⑸调整复合衬砌荷载分配,使二衬承受部分围岩荷载,充分利用复合衬砌的承载能力,在初步复合衬砌设计方案的基础上,合适的一、二衬荷载分配,能减小衬砌在施工和通水工况下的切向应力值,使其满足材料强度要求,同时提高围岩安全系数。设置一衬加载后及二衬加载前的围岩开挖洞周径向位移为优化自变量,调节一、二衬荷载分配比,在施工工况和通水工况下,围岩位移值和一、二衬切向应力平均值呈较为明显的线性关系。更多还原

【Abstract】 The urban long water transfer project solves the urban residents’domestic water consumption and urban industrial water consumption by inter-regional water transfer,guarantees agricultural grain production,alleviates the pressure of urban groundwater exploitation,and supports for ecological environment protection.In this paper,based on the urban water conveyance project in Jilin Province,six typical sections of TBM and blasting are selected as the research objects in the construction scheme of the water mains.Two-dimensional numerical modeling was performed using Abaqus finite element software to analyze the surrounding rock stability and lining structure design.The lining optimization design is carried out by adjusting the thickness of the lining and the load distribution of the double lining.The main results are as follows:⑴Contrasting and analyzing the influence of drilling and TBM on the stability of surrounding rock after tunnel excavation,and reducing the physical and mechanical parameters of surrounding rock in the excavation section of drilling,simulating the damage of surrounding rock by drilling.In the section excavated by drilling,the principal stress value of the surrounding rock is discontinuous in the surrounding rock distrubed zone and the adjacent unaffected zone.Tunnel excavation results in a decrease in rock mass stiffness in the surrounding rock disturbance zone,making its minimum principal stress greater than that of adjacent unaffected areas.⑵After the excavation of the tunnel,the maximum principal stress and the minimum principal stress of the surrounding rock plane are both negative values,indicating that the surrounding rock units are under pressure and conform to the mechanical properties of the rock compressive strength greater than the tensile strength,calculating the surrounding rock safety factor F_s Value,and some sections have a safety factor less than one.⑶After the first lining is loaded,the tangential stress of first lining unit is negative,and the radial displacement of the surrounding rock is directed to the inside of the cave,which can fully exert the mechanical properties of the lining material.The safety factor of the surrounding rock unit in some sections is less than 1,indicating there is room for optimization in the preliminary lining design.After the lining of the secondary lining,due to the effect of internal water pressure,the tangential compressive stress of the lining is reduced,and the safety factor of the surrounding rock of each section is improved,indicating that the water-passing conditions contribute to the stability of the surrounding rock and lining.⑷Increasing the thickness of first lining,under the working conditions and water-passing conditions,the tangential stress of the lining is reduced,and the safety factor of the surrounding rock is increased to varying degrees.Under the same composite lining optimization scheme,the tangential stress of the lining is reduced with different rate.Under the water-passing condition,the thickness of first lining has a linear relationship with the average value of the tangential stress of the first and secondary linings.⑸Adjust the load distribution of the double lining so that the secondary lining can bear part of the surrounding rock load to make full use of the bearing capacity of the double lining.On the basis of the preliminary composite lining design,the appropriate first and secondary lining load distribution can reduce the tangential stress value of the lining under construction and water-passing conditions,so that it meets the material strength requirements and improves the surrounding rock safety factor.The radial displacement of the surrounding rock after the loading of first lining and before the loading of the secondary lining is set as the independent variable to optimize the lining design,under construction conditions and water supply conditions,the displacement value of surrounding rock and the average value of the tangential stress of the first and secondary linings are obviously linear.更多还原