上覆富水砂层隧道开挖面稳定性分析与注浆加固对策研究

发布时间：2018-05-28 03:05

本文选题：富水砂层 + 流砂层　；参考：《山东大学》2017年博士论文

【摘要】：改革开放以来,我国经济飞速发展,尤其是东部沿海地区人口数量急剧增加,造成交通拥堵、交通效率低下,制约着城市的进一步健康发展,因此修建地铁轨道交通是城市发展的必然选择。而在滨海城市中修建地铁则经常会遇到富水软弱砂层地质,由于其比较松散、粘聚力小、孔隙率大、渗透系数大、含承压水等,隧道开挖扰动下极容易导致开挖面发生失稳破坏,诱发涌水涌砂等工程灾害。若处理措施不当,将导致地面塌陷、隧道塌方等工程事故,严重影响施工进度,并带来恶劣的社会影响。鉴于此,富水砂层隧道开挖面稳定性及注浆加固控制对策成为我国地下工程建设中的亟需解决的关键科学问题。本文采用现场调研,室内试验,理论分析,数值模拟以及现场试验相结合的研究方法,以青岛地铁2号线啤—苗区间为研究对象,对上覆流砂层隧道开挖面失稳破坏机理及注浆加固控制对策进行了系统的研究,取得的一系列研究成果,具体体现在以下几个方面:(1)在总结典型青岛地铁开挖面塌方案例的基础上,对青岛地铁富水砂层段土体物理力学参数进行了全面系统的室内试验研究,并重点研究了粉质粘土隔水层在不同含水率影响下力学性质的变化规律,同时与国内主要地铁城市富水砂层性质进行对比,研究青岛富水砂层由于沉积环境的不同造成的物理力学性质的差异,归纳青岛地铁隧道所处富水砂层的力学特性。(2)结合一般性涌水涌砂事故发生机理,研究了富水砂层发生一般性涌水涌砂事故存在客观条件,对青岛地铁浅埋暗挖区间依次进行砂源、水源、通道及水动力分析;将动力学理论应用于富水砂层内部的渗流过程,通过建立模型及相关理论公式的分析,研究了涌水涌砂发生判据即颗粒尺寸与流速大小的关系,并从细观角度揭示了青岛地铁隧道特殊富水砂层涌水涌砂灾害的演化机制,从而对其发生涌水涌砂的可能性进行了客观合理地评价。(3)考虑上覆饱水动态流砂层对隧道开挖面稳定性的影响,构造出极限状态下开挖面土体破裂机构,从功能转化平衡的角度,研究了隧道开挖面稳定性上限分析,并利用强度折减方法和重力加载方法,分别建立了隧道开挖面安全系数,得到了临界土体破裂范围及破裂模式;通过理论分析与计算,研究了不同开挖面土体粘聚力、内摩擦角、重度、隔水层厚度、流砂层水土压力及隧道开挖高度等参数对上覆饱水动态流砂层地质条件下隧道开挖面稳定性影响。(4)为进一步验证理论推导的正确性,建立了多种数值计算模型,运用统计分析的方法研究了流砂层厚度、隔水层厚度,隔水层粘聚力、内摩擦角等不同影响因素下隧道开挖面变形失稳、围岩应力变化特征,得到了各因素对开挖面失稳的影响关系和敏感指标;通过分析开挖过程中隧道拱顶—拱腰—开挖面应力和位移变形规律,引入了位移释放系数和应力释放率,揭示围岩与开挖面在隧道开挖过程中的影响关系,分析研究开挖过程中围岩与开挖面变形速率先后顺序,探索了隧道空间变形特征。(5)结合前期理论分析和室内试验研究成果,对青岛地铁富水砂层超前预注浆加固关键技术及注浆加固圈厚度等关键参数进行了系统研究,建立了地表变形控制与实时注浆参数动态响应机制。并基于砂层注浆加固参数与围岩变形特征,通过数值模拟对比分析,优选适用于上覆流砂层地质条件下开挖面的开挖工法,时结合钻孔雷达、室内力学试验、跟踪监测等手段对注浆控制控制效果进行评价,以确保隧道围岩稳定性,最终保证了隧道各区间的顺利贯通,并取得了良好的效果,具有一定的指导意义。
[Abstract]:Since the reform and opening up, China's economy has developed rapidly, especially in the eastern coastal areas, the population number has increased dramatically, causing traffic congestion and low traffic efficiency, restricting the further healthy development of the city. Therefore, the construction of metro rail transit is an inevitable choice for urban development, while the construction of the subway in the coastal cities often meets the water and weakness. Sand geology, because of its loose, cohesive force, large porosity, large permeability coefficient, bearing pressure water, and so on. Under the disturbance of tunnel excavation, it is very easy to cause instability and damage of the excavation surface and induce water gushing and sand pouring. If the treatment measures are not appropriate, it will lead to ground collapse, tunnel collapse and other engineering accidents, which seriously affect the construction progress, and bring serious impact on the construction progress, and bring the construction progress seriously. In view of this, the stability of the excavation surface of the water rich sand tunnel and the control measures for grouting reinforcement are the key scientific problems to be solved in the construction of underground engineering in China. This paper adopts the research method of field investigation, indoor test, theoretical analysis, numerical simulation and field test, with the beer of Qingdao Metro Line 2 - The seedling interval is the research object. A systematic study is made on the failure mechanism of the excavation surface of the overlying tunnel and the control measures of grouting reinforcement. A series of research results obtained are embodied in the following aspects: (1) on the basis of a typical case of the typical Qingdao subway excavation face collapse, the soil physics of the water rich sand section of the Qingdao subway is carried out. The mechanical parameters are studied in a comprehensive and systematic laboratory, and the change law of the mechanical properties of the silty clay aquifers under the influence of different water content is emphatically studied. At the same time, it is compared with the nature of the main subway urban rich water sand layer in China, and the difference of physical and mechanical properties caused by the different sedimentary environment in the Qingdao rich water sand layer is studied. The mechanical characteristics of the water rich sand layer in Qingdao subway tunnel are summed up. (2) combining with the mechanism of general water gushing and sand pouring accident, the objective conditions for the occurrence of general water gushing and sand pouring accident in the rich water sand layer are studied. The analysis of the sand source, water source, channel and hydrodynamic force is carried out in order of the shallow underground excavation in Qingdao subway, and the theory of dynamics is applied to the rich. The seepage process in the water sand layer, through the analysis of the model and the related theoretical formula, has studied the relation between the criterion of sand gushing and the particle size and the velocity of flow, and reveals the evolution mechanism of the sand gushing and sushing disaster in the special rich water sand layer of Qingdao subway tunnel from the meso angle, thus the possibility of water gushing and sushing is carried out. Objective and reasonable evaluation. (3) considering the influence of the dynamic flow sand layer on the stability of the tunnel excavation surface, the soil fracture mechanism of the excavation face under the limit state is constructed. The upper limit analysis of the stability of the tunnel is studied from the angle of the function transformation balance, and the tunnel is established by the strength reduction method and the gravity loading method. Through theoretical analysis and calculation, the parameters of soil cohesive force, internal friction angle, gravity, water layer thickness, water and soil pressure of flow sand layer and tunnel excavation height are studied by theoretical analysis and calculation. (4) in order to further verify the correctness of the theoretical deduction, a variety of numerical calculation models have been established, and the deformation instability of the tunnel excavation surface and the characteristics of the surrounding rock stress change under different influence factors such as the thickness of sand layer, the thickness of the aquifers, the cohesive force of the aquifers, the internal friction angle and so on are studied by statistical analysis. By analyzing the stress and displacement deformation of tunnel vault, arch waist and excavation face during excavation, the displacement release coefficient and stress release rate are introduced, and the influence of surrounding rock and excavation surface on tunnel excavation is revealed, and the sequence of deformation rate of surrounding rock and excavation face in excavation process is analyzed and studied. The spatial deformation characteristics of the tunnel are taken into account. (5) combining the previous theoretical analysis and laboratory research results, the key parameters such as the key technology and the thickness of the grouting reinforcement ring are systematically studied, and the dynamic response mechanism of the surface deformation control and the real-time grouting parameters is established, based on the grouting of the sand layer. In order to ensure the stability of the grouting control by means of drilling radar, indoor mechanical test, tracking monitoring and so on, the stability of the tunnel surrounding rock is ensured and the various sections of the tunnel are ensured. It has achieved good results and has certain guiding significance.
【学位授予单位】：山东大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：U455.49

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