【作者】 薛瑞华；

【导师】 何本国；

【作者基本信息】 东北大学 ， 采矿工程， 2023， 硕士

【摘要】 水利发电建设工程在我国的稳步推进,越来越多的水电站在江河流域建成。引水隧洞工程作为水利发电重要的一环,其安全施工与运营受到越来越多学者专家的重视。隧洞在建设过程中,不可避免的需要穿越富水山岭、断层破碎带,由于隧洞开挖过程中应力场与渗流场的叠加耦合,造成施工过程中的大变形、塌方、涌水涌泥的安全事故的发生。本文依托四川省甘孜藏族自治州硬梁包引水隧洞工程,采用数值分析计算并结合现场施工概况与监测数据的方法,对该引水隧洞流固耦合作用下的隧洞稳定性、渗流场分布情况进行分析,从而为施工过程提供有效建议。主要研究如下:(1)采用FLAC3D数值计算软件,模拟隧洞流固耦合开挖过程,通过对比不同外水水头高度对数值计算结果的影响,得到渗流作用下引水隧洞施工时的围岩变形、支护结构受力、塑性区分布特点,研究结果表明:隧洞变形以拱顶沉降为主,受水头高度影响最大;初期支护结构上拱肩受力明显,随着外水水头增加,初期支护受力增大;围岩开挖后,隧洞区范围主要集中在隧洞周围,在拱肩以及拱脚附近会进一步发育,并且在高水头作用下,拱顶范围围岩拉破坏范围加大。(2)基于硬梁包引水隧洞围岩条件,明确合理注浆圈参数与合理注浆范围,确定复合式衬砌结构的外水压力折减系数,在注浆圈厚度取5m,灌浆防渗效果根据相关工程经验保守取值nrg=200时,衬砌结构外水压力折减系数取0.7;使用ANSYS有限元软件,采用荷载结构法分析衬砌结构能够承受的不同形式荷载能力,外水压力控制拱腰与拱脚附近的结构安全,单一围岩压力控制拱肩附近的结构安全,其余部位由较大的安全裕度,根据设计荷载确定衬砌设计的最小安全系数为3.3,满足安全规范要求。(3)研究断层破碎带对引水隧道开挖的影响,对比不同工况下隧洞变形量、初支结构受力、围岩塑性区分布、渗流场分布特点等,得出断层破碎的存在异化了隧洞变形及受力特点这一结论,与隧洞走向近乎平行的断层显著降低了隧洞施工期间的稳定性,并根据现场实测典型断面的变形量验证了这一观点,为实际隧洞通过断层带的施工支护与安全监测提供建议。(4)分析讨论了类似不良地质条件下隧洞发生涌水涌泥灾害后的治理措施,相关工程大多采用施工排水孔的方法降低隧洞外水压力,利用注浆加固方法提高围岩的稳定性,能够有效控制不良地质条件下的围岩稳定性。硬梁包引水隧洞针对涌水涌泥灾害发生后的治理措施主要分为塌方段与受塌方影响段内的围岩,采用超前帷幕注浆的方式处理已经发生塌方灾害的围岩,采用径向注浆的方法处理受塌方影响段。根据现场施工反馈,采用的控制加固围岩方法能够有效处理隧洞灾害,抑制围岩进一步劣化。更多还原

【Abstract】 The steady advancement of water conservancy power generation construction projects in our country,and more and more hydropower stations have been built in river basins.As an important part of water power generation,the safety construction and operation of diversion tunnel has been paid more and more attention by scholars and experts.In the process of construction,the tunnel inevitably needs to pass through the rich mountains and fault fracture zones.Due to the superposition and coupling of stress field and seepage field in the process of tunnel excavation,safety accidents such as large deformation,collapse,water gushing and mud gushing occur in the construction process.Based on the Yingliangbao diversion tunnel project in Garze Tibetan Autonomous Prefecture of Sichuan Province,this thesis analyzes the stability and seepage field distribution of the diversion tunnel under the action of fluid-structure interaction by using numerical analysis and calculation combined with the construction situation and monitoring data,so as to provide effective suggestions for the construction process.The main research is as follows:(1)FLAC3D numerical calculation software was used to simulate the coupled water-rock excavation process of the tunnel.By comparing the influence of different external water head heights on the numerical calculation results,the characteristics of surrounding rock deformation,supporting structure stress and plastic zone distribution under the action of seepage were obtained.The research results show that the tunnel deformation is mainly caused by the arch settlement,which is most affected by the head height.The stress on the spandrel of the initial support structure is obvious,and with the increase of the external water head,the initial support stress increases.After surrounding rock excavation,the area of tunnel is mainly concentrated around the tunnel,and will be further developed near the spandrel and arch foot.Moreover,under the action of high water head,the tensile failure range of surrounding rock in the arch area is increased.(2)Based on the surrounding rock conditions of the Yingliangbao diversion tunnel,the reasonable parameters of the grouting ring and the reasonable range of the grouting were determined,and the external water pressure reduction coefficient of the composite lining structure was determined.When the thickness of the grouting ring was 5m and the anti-seepage effect of grouting was conservative value nrg=200 according to relevant engineering experience,the external water pressure reduction coefficient of the lining structure was 0.7.ANSYS finite element software was used to analyze the capacity of different forms of loads that the lining structure could bear by load structure method.External water pressure controlled the structural safety near the arch waist and arch foot,single surrounding rock pressure controlled the structural safety near the spinner,and the rest parts had a large safety margin.According to the design load,the minimum safety factor of the lining design was determined to be 3.3,meet the safety specifications.(3)Through the numerical simulation method,the influence of fault fracture zone on the excavation of diversion tunnel is studied,and the deformation of tunnel,the stress of initial support structure,the distribution of plastic zone in surrounding rock and the distribution characteristics of seepage field are compared under different working conditions.It is concluded that the existence of fault fracture dissimilates the deformation and stress characteristics of tunnel.The fault almost parallel to the strike of the tunnel significantly reduces the stability of the tunnel during construction.This view is verified by the deformation of the typical section measured in the field,which provides suggestions for the construction support and safety monitoring of the actual tunnel through the fault zone.(4)This thesis analyzes and discusses the treatment measures after the disaster of water gusher and mud gusher occurred in the tunnel under similar adverse geological conditions.Most of the related projects use the method of drainage hole construction to reduce the water pressure outside the tunnel,and the method of grouting reinforcement to improve the stability of surrounding rock,which can effectively control the stability of surrounding rock under adverse geological conditions.The treatment measures of hard beam clad diversion tunnel after the occurrence of water and mud gushing disaster are mainly divided into collapse section and the surrounding rock in the section affected by collapse.The method of advanced curtain grouting is used to treat the surrounding rock which has already suffered collapse disaster,and the method of radial grouting is used to treat the affected section.According to the site construction feedback,the control and reinforcement method adopted can effectively deal with tunnel disasters and restrain the further deterioration of surrounding rock更多还原