【作者】 王涛；

【导师】 黄强兵；

【作者基本信息】 长安大学 ， 土木工程， 2020， 硕士

【摘要】 高速铁路是我国基础设施建设的“名片”,近年来我国高铁建设规模之大,建设速度之快,前所未有!高速铁路建设对我国“一带一路”国家战略的实施和国民经济的快速发展起到了重要的推动作用。然而,我国幅员辽阔,地质条件复杂,崩滑流、地面沉降地裂缝及岩溶等不良地质发育,已建和拟建的多条高速铁路不可避免地穿越地裂缝发育区。地裂缝带作为一种地质软弱带,跨越地裂缝带高铁路基在列车长期振动荷载作用下,可能因地裂缝带两侧地层差异沉降导致路基动力失稳破坏,威胁高铁运营安全。因此,开展跨地裂缝带高铁路基长期动力稳定性及长期沉降研究具有十分重要的现实意义和工程实用价值。本文以大西（大同至西安）客运专线跨越山西太原盆地地裂缝为工程背景,依托国家自然科学基金项目“高速铁路跨地裂缝带路基动力响应机制及长期沉降研究（41772274）”,采用野外现场测试、室内试验、理论解析和动力有限元数值模拟相结合的方法,对列车振动荷载作用下跨地裂缝带路基长期动力稳定性及沉降进行研究,研究成果可为跨地裂缝带高铁路基设计与病害防治提供科学依据。主要研究成果如下:（1）通过现场钻孔剪切波速测试和地脉动测试,对地裂缝带场地动力特性进行了研究,结果表明东观变电站地裂缝场地土体剪切波速沿深度方向突变较大,地脉动信号的频谱特征为多峰型,两种测试方法在地层结构反演方面一致性良好,地脉动测试相比于剪切波速测试得到的场地卓越周期偏大,场地类型偏于更好级别。（2）基于土体累积塑性变形室内循环三轴试验,对循环加载条件下的土体累积塑性变形特征、变形影响因素和变形描述模型进行了研究,结果表明土体累积塑性变形可分为急速增长、稳定增长和稳定段三个阶段;累积塑性变形随列车荷载动、静偏应力和含水率的增加而增加,随围压和埋深的增加而减小;Allometric1模型（?_p（28）AN^b）在描述土体累积塑性变形和变形影响因素时的精度和简便实用性均较为优异。（3）通过三维动力有限元数值模拟计算,研究了动应力和列车振动速度沿路基纵向和深度方向的响应特征,确定了地裂缝影响区范围和影响区范围内的动力响应放大系数。结果表明采用复合地基加固后,路堤中动应力增大,CFG桩加固范围内的地基动应力大幅减小,路堤和列车振动荷载主要影响深度范围内的地基的振动速度均减小;动应力和振动速度的地裂缝影响区范围在路堤中不变、地基中减小;动应力放大系数在路堤和地基中均减小,振动速度放大系数在路堤中不变,地基中增大。（4）基于列车振动荷载和环境激励实测法、临界动应力法和有效振速法对跨地裂缝带高铁路基动力稳定性进行了研究,结果表明列车经过地裂缝带路基时不会发生共振破坏,满足跨地裂缝带路基动力稳定性要求的路基土体最小处理深度为:地裂缝影响区内:H₀≥6.1m（距离路基顶面）,处理范围为上盘距离地裂缝₀L=15m,下盘距离地裂缝₀L=10m。（地裂缝90°正交于路基）;地裂缝影响区外:H₁≥5.5m（距离路基顶面）。（5）通过多因素耦合作用土体累积塑性变形试验,建立了考虑多因素耦合作用的长期沉降预测模型,研究了跨地裂缝带高铁路基长期沉降的时间发展特性和空间分布特性,结果表明路基沉降在线路运营初期发展较快,地裂缝沉降影响区范围为上盘小于下盘,采用复合地基加固后,上、下盘路基总沉降量和地裂缝影响区内的差异沉降量均减小,地裂缝沉降影响区范围也减小。更多还原

【Abstract】 High-speed railway is the name card of China’s infrastructure construction,in recent years,the constructing scale and speed of China’s high-speed railway is unprecedented!The construction of high-speed railway plays a positive and important role in promoting the implementation of"The Belt and Road"national strategy and the rapid development of national economy.However,China is a vast country with complex geological conditions.Adverse geological phenomena such as collapse,landslide,debris flow,land subsidence,ground fissures and karst are very common in China.A number of high speed railways,both built and proposed,will inevitably pass through the ground fissure zone.As a kind of geological weak zone,the ground fissures zone may lead to the dynamic instability and damage of subgrade due to the differential settlement of the stratum on both sides of the ground fissures zone under the long-term vibration load of the train,thus threatening the operation safety of the high-speed railway.Therefore,it is of great practical significance and practical engineering value to study the long-term dynamic stability and settlement of high railway foundation across the ground fissures zone.This paper takes the Daxi（Datong to Xi’an）passenger dedicated line crossing the ground fissures in Taiyuan basin of Shanxi Province as the engineering background,relying on the project of national natural science foundation of China"Study on dynamic response and long-term settlement of high-speed railway subgrade crossing ground fissures zone（41772274）".By combining field test,laboratory test,theoretical analysis and dynamic finite element numerical simulation,the long-term dynamic stability and long-term settlement of subgrade across ground fissures zone under the action of train vibration load were studied.The research results can provide a scientific basis for the design and disease control of high railway foundation in the cross-ground fissures zone.The main research results are as follows:（1）Through shear wave velocity and ground pulsation in-situ test,the dynamic characteristics of ground fissures zone were studied.The results show that the shear wave velocity of soil in the ground fissures site of Dongguan substation changes sharply along the direction of depth.The spectrum characteristics of ground pulsation signal are multi-peak.Both of the two test methods have good consistency in inversion of formation structure.Compared with the shear wave velocity test,the site pulsation test has a larger excellent period and a better site type.（2）Based on the cyclic triaxial test in the chamber of soil cumulative plastic deformation,the soil cumulative plastic deformation characteristics,deformation influencing factors and deformation description model under cyclic loading were studied.The results show that the cumulative plastic deformation of soil can be divided into three stages:rapid growth section,stable growth section and stable section.The cumulative plastic deformation increases with the increase of dynamic deviatoric stress,static deviatoric stress and water content,and decreases with the increase of confining pressure and depth.Model of Allometric1(?_p^（28）a N^b)has excellent accuracy and practicability in both describing the cumulative plastic deformation of soil and the influencing factors of deformation.（3）By means of three-dimensional dynamic finite element numerical simulation,the response characteristics of dynamic stress and vibration velocity along the subgrade longitudinal direction and depth direction are studied,and the dynamic response amplification coefficients within the affected zone of ground fissure and the affected zone are determined.The results show that after reinforced by the composite foundation,the dynamic stress in the embankment increases,the dynamic stress of foundation within the scope of CFG pile reinforcement decreases significantly,the vibration velocity of the foundation within the depth of the embankment and the train is reduced,the influence zones of dynamic stress and vibration velocity on ground fissures are unchanged in embankment and decreased in foundation,the dynamic stress amplification coefficient decreases in both embankment and foundation,while the vibration velocity amplification coefficient does not change in embankment,but increases in foundation（4）Based on the train vibration load and environmental excitation measurement method,the critical dynamic stress method and the effective vibration velocity method,the dynamic stability of high railway foundation across the ground fissures zone is studied.The results show that no resonance damage will occur when the train passes through the subgrade of the ground fissures zone.The minimum treatment depth of roadbed soil that meets the dynamic stability requirements of roadbed with cross-ground fissures zone is:Area inside the ground crack affects:H₀≥6.1m（from the top of the roadbed）,and the treatment range is hanging wall distance ground fissure ₀L=15m,footwall distance ground fissure ₀L=10m（the ground fissure is 90°orthogonal to the roadbed）;Area outside the ground crack affects:H₁≥5.5m（from the top of the roadbed）.（5）Based on the cumulative plastic deformation test of soil mass under multi-factor coupling effect,a long-term settlement prediction model considering multi-factor coupling effect was established,and then the temporal development characteristics and spatial distribution characteristics of the long-term settlement of high railway foundation across the ground fissures zone were studied.The results showed that the subgrade settlement developed rapidly in the early stage of the line operation.The area affected of hanging wall by the ground crack settlement was smaller than that of the footwall.After the composite foundation was adopted to reinforce the subgrade,the total settlement amount of hanging wall and footwall subgrade and the differential settlement amount in the affected area of ground crack both decreased,and the affected area of ground crack settlement also decreased.更多还原