成都泥岩地层盾构施工控制技术研究

发布时间：2018-11-21 13:52

【摘要】：随着经济的发展,我国进入了地铁修建的高峰期。与此同时,地铁的修建改变了地层位移场和应力场的分布,导致邻近建筑物产生附加变形和内力,影响建筑物的可靠性,而盾构施工法是目前地铁施工中普遍使用的施工方法,因此盾构施工对地层变形及邻近建筑物的影响及如何控制这些影响成为当前地下空间开发利用遇到的重要问题。本文采用工程类比、理论推导和现场实验等方法,对此问题进行了研究,主要研究内容及结论包括:1、对盾构施工诱发地层扰动及变形机理进行了理论分析,并将诱发因素分为两大类:力学作用及地层损失作用。其中力学作用主要考虑了盾构机刀盘正面对工作面的附加推力q、刀盘正面摩擦力fd、盾壳摩擦力fs及盾尾注浆压力p;而地层损失主要考虑由盾尾间隙引起。对Mindlin解析式进行积分推导,得到了力学作用的三维地层位移解析公式;结合Loganathan二维土体位移解与Verruijit的三维位移解,推导了非等量径向位移模式地层三维位移解。2、力学作用与地层损失对土体位移的量化分析对比结果表明地层损失引起的地层位移占总位移的95%左右。通常采用盾尾同步注浆及二次注浆工艺来减小地层损失从而达到控制地层位移的目的,但由于注浆液硬化后体积收缩导致盾尾间隙无法得到完全填充,浆液体积收缩率范围为8.4%～9.8%,因此在渗透性较差的地层中,注浆量约为理论注浆量的1.1倍,随着地层渗透性的增加,注浆量要适当的增加。3、采用基于协同作用弹性地基梁模型与基于受约束协同作用弹性剪弯梁模型研究分析了邻近建筑物受地层位移影响产生的附加位移与附加内力,研究结果表明:地基基床系数小、建筑物整体刚度小的建筑物能够更好的适应盾构施工的扰动;对于整体刚度较大的建筑物,盾构施工对结构内力的影响较为明显,而对建筑物倾斜的影响较小;4、运用两阶段法研究分析了邻近桩基受盾构施工的影响,研究发现邻近桩基附加内力对桩隧间距反应敏感,根据桩基附加内力与桩隧间距的变化关系将隧道周围土体划分为强影响区、弱影响区及无影响区并给出了划分标准。5、研究分析了泡沫剂改良渣土的微观机理及泡沫半衰期的影响因素,并将研究结果成功运用于解决本文依托工程出现的问题。实践表明:采用泡沫剂改良含水量低的泥岩时,若刀盘喷水不足时,渣土将呈块状且传输时出现打滑现象,盾构掘进速度慢;加大刀盘喷水后渣土流塑性得到改善,盾构掘进速度也明显得到提高。
[Abstract]:With the development of economy, our country has entered the peak period of subway construction. At the same time, the construction of subway has changed the distribution of ground displacement field and stress field, resulting in additional deformation and internal force of adjacent buildings, which affects the reliability of buildings. The shield construction method is widely used in subway construction at present. Therefore, the influence of shield construction on formation deformation and adjacent buildings and how to control these effects have become an important problem in the development and utilization of underground space. In this paper, engineering analogy, theoretical derivation and field experiments are used to study this problem. The main research contents and conclusions are as follows: 1. The mechanism of formation disturbance and deformation induced by shield construction is analyzed theoretically. The induced factors are divided into two categories: mechanical action and formation loss. The mechanical effect mainly considers the additional thrust Q of the face facing the cutter head of shield machine, the friction force of the fd, shield shell on the front side of the cutter head and the grouting pressure p of the shield tail, while the formation loss is mainly caused by the shield tail clearance. Based on the integral derivation of the Mindlin analytic formula, the analytical formula of three-dimensional stratum displacement is obtained. Combined with Loganathan's two-dimensional soil displacement solution and Verruijit's three-dimensional displacement solution, the three-dimensional displacement solution of heterogeneous radial displacement model is derived. 2. The quantitative analysis of soil displacement caused by mechanical action and formation loss shows that the formation displacement caused by formation loss accounts for about 95% of the total displacement. In order to reduce the formation loss and control the formation displacement, the synchronous grouting and secondary grouting are usually used to control the formation displacement. However, due to the volume shrinkage of the grouting fluid after hardening, the shield tail clearance can not be completely filled. The volume shrinkage rate of the slurry is 8.4 / 9.8. therefore, in the stratum with poor permeability, the grouting volume is about 1.1 times that of the theoretical grouting quantity. With the increase of the permeability of the formation, the grouting quantity should be increased appropriately. The additional displacement and additional internal force caused by ground displacement in adjacent buildings are studied by using the model of elastic foundation beam based on synergetic action and the model of elastic shear beam based on constrained synergistic action. The results show that the coefficient of foundation bed is small. The small stiffness of the whole building can better adapt to the disturbance of shield construction; For the buildings with larger overall stiffness, the shield construction has a more obvious effect on the internal force of the structure, while the influence on the inclination of the building is relatively small. 4. The influence of shield construction on adjacent pile foundation is analyzed by using two-stage method. It is found that the additional internal force of adjacent pile foundation is sensitive to the response of pile tunneling spacing. According to the relationship between the additional internal force of pile foundation and the distance between pile and tunnel, the soil around the tunnel is divided into strong influence area, weak influence zone and unaffected area, and the dividing standard is given. The microcosmic mechanism of foaming agent modified residue and the influencing factors of foam half-life were analyzed, and the results were successfully applied to solve the problems in this paper. The practice shows that when the foam agent is used to improve the mudstone with low water content, if the blade head is short of water spray, the residual soil will be block and slip when it is transported, and the speed of shield tunneling will be slow; The residual soil flow plasticity is improved and the speed of shield tunneling is improved obviously.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U455.43

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