盾构掘进对砂卵石地层的扰动机理研究
发布时间：2018-09-05 21:12
【摘要】：城市地铁区间隧道采用盾构法施工已发展成为趋势,地铁隧道所穿越地层的工程地质条件成为影响盾构隧道安全施工的关键因素。我国地域幅员辽阔,地质条件错综复杂,盾构隧道穿越特殊复杂地质条件时将面临许多亟待解决的技术难题。砂卵石地层是一种典型的力学不稳定地层,颗粒之间无粘聚力,无水状态下,卵石颗粒之间点对点传力,在盾构掘进扰动作用下,地层反应灵敏,地层原有的相对稳定或平衡状态很容易受到破坏,形成地层损失和围岩扰动。后期在地下水、地面荷载等作用下,地层损失逐渐发展至地表,导致地面坍塌。论文以我国城市地铁区间隧道在砂卵石地层中掘进为工程背景,结合国家重点基础研究发展计划(973计划)课题“复杂环境作用下地下结构的长期安全性及其预测方法”和西南交通大学博士创新基金资助项目“盾构掘进对砂卵石地层的扰动机理研究”开展研究。综合采用理论分析、模型试验、数值模拟等研究方法,探讨砂卵石地层中盾构掘进引起的地层扰动机理,通过室内掘进试验和颗粒离散元软件从宏观和细观层面上研究盾构掘进对砂卵石地层的扰动特性,取得主要成果如下：1、分析了砂卵石地层中盾构掘进对地层的扰动机理和滞后沉降的形成原因,建立了二维颗粒离散元分析模型,得到了盾构掘进对开挖面前面土体和洞周土体的扰动性态,在此基础上提出了针对砂卵石地层盾构掘进引起的土体扰动分区示意图。从细观层面上分析了滞后沉降的发展过程和影响因素,提出了减小滞后沉降形成的控制措施。2、研制了盾构掘进试验系统,包括Φ800mm土压平衡式盾构机、盾构始发装置、管片衬砌结构及其它附属设备。结合室内试验,得到了试验砂卵石地层的物理力学参数、颗粒级配曲线、渣土改良和地层加固方案。结合砂卵石地层特性,建立了适用于砂卵石地层中盾构掘进参数的计算公式。3、采用Φ800mm土压平衡式盾构掘进试验系统开展了盾构穿越砂卵石地层的室内掘进试验,从地层横、纵断面分析了盾构在掘进不同阶段引起的地层扰动特点,得到了不同埋深地层的变形特点和扰动范围。分析了盾构在实施渣土改良、地层加固等措施后的掘进参数变化特点以及地层变形动态响应,探讨了盾构在不同掘进区段时掘进参数之间的相互关系,对比分析了盾构在穿越不同级配砂卵石地层时的重要掘进参数,建立了不同盾构掘进参数间的数学模型。4、采用颗粒离散元方法建立了包含土仓、盾构刀盘、螺旋出土器以及掘进土槽的土压平衡式盾构掘进分析模型,对砂卵石地层中盾构掘进全过程进行了模拟,从土体颗粒位移、接触状态和地层应力状态方面分析了盾构掘进对地层的扰动范围、沉降形态以及地层动态移动变化规律；建立了盾构顶推速度、刀盘转速、出土率等掘进参数与地层扰动的相互联系。随着国家进一步开放城市地铁建设的权限,越来越多的城市将会加入到地铁建设的浪潮,地铁盾构隧道建设也将面临更多、更复杂的技术挑战。本论文研究成果可为研究盾构隧道施工对地层的扰动影响,尤其是类似砂卵石这种离散性地层,保障盾构隧道的安全掘进和减小盾构掘进对周围环境的影响提供参考。
[Abstract]:Shield tunneling has become a trend in the construction of metro tunnels in urban areas, and the engineering geological conditions of metro tunnels passing through strata have become the key factors affecting the safe construction of shield tunnels. The sandy pebble stratum is a typical unstable stratum with no cohesion between the pebbles. In the absence of water, the pebble particles transfer force from point to point. Under the action of shield tunneling disturbance, the stratum reacts sensitively, and the original relative stability or equilibrium state of the stratum is easy to be destroyed, resulting in formation loss and surrounding rock disturbance. In this paper, the long-term safety of underground structures under complex environment and its prediction methods are studied under the background of tunneling in sandy gravel stratum of urban subway in China and the subject of National Key Basic Research and Development Program (973 Program). The research on the disturbance mechanism of shield tunneling in sandy gravel stratum is carried out by means of theoretical analysis, model test and numerical simulation. The disturbance mechanism caused by shield tunneling in sandy gravel stratum is discussed through laboratory tunneling test and particle discrete element software. The disturbance characteristics of shield tunneling on sandy gravel stratum are studied from macroscopic and microscopic aspects. The main results are as follows: 1. The disturbance mechanism of shield tunneling on sandy gravel stratum and the cause of hysteretic settlement are analyzed. A two-dimensional particle discrete element analysis model is established, and the soil mass and cave in front of excavation are obtained. Based on the perturbation behavior of surrounding soil, the zoning diagram of soil disturbance caused by shield tunneling in sandy gravel stratum is proposed. The development process and influencing factors of lag settlement are analyzed from the meso-level, and the control measures to reduce the formation of lag settlement are put forward. 2. The shield tunneling test system is developed, including 800mm earth pressure balance. Shield machine, shield starting device, segment lining structure and other ancillary equipment. Combining with laboratory tests, the physical and mechanical parameters, grain gradation curve, slag soil improvement and stratum reinforcement schemes of the test sandy gravel stratum are obtained. Laboratory tunneling test of shield tunneling through sandy gravel stratum was carried out with 800mm earth pressure balance shield tunneling test system. The characteristics of stratum disturbance caused by shield tunneling in different stages were analyzed from horizontal and vertical sections of stratum, and the deformation characteristics and disturbance range of stratum with different buried depth were obtained. Variation characteristics of tunneling parameters and dynamic response of stratum deformation after consolidation measures are discussed. The relationship between tunneling parameters of shield tunneling in different tunneling sections is discussed. The important tunneling parameters of shield tunneling in different graded sandy gravel stratum are compared and analyzed. The mathematical model of tunneling parameters of different shield tunneling is established. 4. The particle separation is adopted. The model of earth pressure balanced shield tunneling including soil bunker, shield cutter head, screw excavator and tunneling trench is established by using the scattered element method. The whole process of shield tunneling in sandy gravel stratum is simulated. The disturbance range and settlement form of shield tunneling to stratum are analyzed from the aspects of soil particle displacement, contact state and stratum stress state. The relationship between tunneling parameters such as shield pushing speed, cutter head speed, excavation rate and stratum disturbance is established.With the further opening of the authority of urban subway construction, more and more cities will join the wave of subway construction, and the construction of subway shield tunnel will face more and more. The research results of this paper can provide a reference for studying the disturbance effect of shield tunneling on strata, especially in discrete strata such as sandy gravel, ensuring the safety of shield tunneling and reducing the influence of shield tunneling on the surrounding environment.
【学位授予单位】：西南交通大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：U455.43
[Abstract]:Shield tunneling has become a trend in the construction of metro tunnels in urban areas, and the engineering geological conditions of metro tunnels passing through strata have become the key factors affecting the safe construction of shield tunnels. The sandy pebble stratum is a typical unstable stratum with no cohesion between the pebbles. In the absence of water, the pebble particles transfer force from point to point. Under the action of shield tunneling disturbance, the stratum reacts sensitively, and the original relative stability or equilibrium state of the stratum is easy to be destroyed, resulting in formation loss and surrounding rock disturbance. In this paper, the long-term safety of underground structures under complex environment and its prediction methods are studied under the background of tunneling in sandy gravel stratum of urban subway in China and the subject of National Key Basic Research and Development Program (973 Program). The research on the disturbance mechanism of shield tunneling in sandy gravel stratum is carried out by means of theoretical analysis, model test and numerical simulation. The disturbance mechanism caused by shield tunneling in sandy gravel stratum is discussed through laboratory tunneling test and particle discrete element software. The disturbance characteristics of shield tunneling on sandy gravel stratum are studied from macroscopic and microscopic aspects. The main results are as follows: 1. The disturbance mechanism of shield tunneling on sandy gravel stratum and the cause of hysteretic settlement are analyzed. A two-dimensional particle discrete element analysis model is established, and the soil mass and cave in front of excavation are obtained. Based on the perturbation behavior of surrounding soil, the zoning diagram of soil disturbance caused by shield tunneling in sandy gravel stratum is proposed. The development process and influencing factors of lag settlement are analyzed from the meso-level, and the control measures to reduce the formation of lag settlement are put forward. 2. The shield tunneling test system is developed, including 800mm earth pressure balance. Shield machine, shield starting device, segment lining structure and other ancillary equipment. Combining with laboratory tests, the physical and mechanical parameters, grain gradation curve, slag soil improvement and stratum reinforcement schemes of the test sandy gravel stratum are obtained. Laboratory tunneling test of shield tunneling through sandy gravel stratum was carried out with 800mm earth pressure balance shield tunneling test system. The characteristics of stratum disturbance caused by shield tunneling in different stages were analyzed from horizontal and vertical sections of stratum, and the deformation characteristics and disturbance range of stratum with different buried depth were obtained. Variation characteristics of tunneling parameters and dynamic response of stratum deformation after consolidation measures are discussed. The relationship between tunneling parameters of shield tunneling in different tunneling sections is discussed. The important tunneling parameters of shield tunneling in different graded sandy gravel stratum are compared and analyzed. The mathematical model of tunneling parameters of different shield tunneling is established. 4. The particle separation is adopted. The model of earth pressure balanced shield tunneling including soil bunker, shield cutter head, screw excavator and tunneling trench is established by using the scattered element method. The whole process of shield tunneling in sandy gravel stratum is simulated. The disturbance range and settlement form of shield tunneling to stratum are analyzed from the aspects of soil particle displacement, contact state and stratum stress state. The relationship between tunneling parameters such as shield pushing speed, cutter head speed, excavation rate and stratum disturbance is established.With the further opening of the authority of urban subway construction, more and more cities will join the wave of subway construction, and the construction of subway shield tunnel will face more and more. The research results of this paper can provide a reference for studying the disturbance effect of shield tunneling on strata, especially in discrete strata such as sandy gravel, ensuring the safety of shield tunneling and reducing the influence of shield tunneling on the surrounding environment.
【学位授予单位】：西南交通大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：U455.43
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