软土地区深基坑变形监测与时空效应分析
发布时间：2019-02-14 20:14
【摘要】：我国东部沿海地区经济发展迅速,城市快速发展对土地资源的需求与日俱增,然而有限的土地资源越来越成为城市发展的重要限制因素,所以地下空间的开发和利用是当今城市发展的主流趋势,尤其是地铁的建设已经成为各大城市交通发展的热点方向。我国东南沿海城市属于典型的软土地基,工程地质状况复杂,施工难度大,施工安全隐患大,因此对软土地区地铁车站深基坑支护结构变形的研究具有重要的实际意义。本文依托无锡地铁2号线梁溪大桥地铁车站深基坑工程,运用现场监测和数值分析的方法,研究了地铁车站深基坑稳定性及其围护体系变形规律。主要工作有:本文结合软土地区特殊的水文地质条件,对软土场地基坑开挖全过程的应力及变形理论进行了研究,重点探讨了深基坑变形的机理及规律,分析了深基坑围护结构变形主要影响因素,并且对深基坑变形的时空效应进行了探讨。结果表明,在基坑开挖与围护过程中,作用在开挖面上的竖向卸荷与作用在围护结构挡土面水平方向卸荷使围护结构的受力和变形随着时间与空间的变化而不断变化,即时空效应贯穿于深基坑开挖的整个过程之中,且软土场地基坑工程的时空效应更加显著。水文和工程地质条件、周边环境、支护体系的类型、深基坑工程设计与施工的规模是影响基坑围护结构变形的主要因素。基于梁溪大桥地铁车站的周边环境和支护方案,制定了该基坑工程施工监测方案,对基坑支护体系的受力和变形进行了实时监测,并对实测数据所呈现的规律进行了研究。对基坑施工过程中支护结构的水平位移、支撑体系轴力变化以及基坑周边地表沉降随基坑开挖深度和时间的变化规律进行了研究。由监测数据分析可知:支撑体系和支护结构对控制基坑的变形具有至关重要的作用,围护墙体的水平位移、周边地表沉降均小于控制值。由于软土场地的流变特性,基坑围护结构变形所呈现出来的时空效应特别显著。建立了数值分析模型对深基坑开挖全过程进行模拟,并且运用FLAC3D软件对围护结构受力和变形性状进行了全过程数值分析,探讨了深基坑围护结构水平位移及地表沉降变化规律,现场监测数据验证了数值模拟模型的合理性和可靠性。
[Abstract]:The economic development in the eastern coastal areas of China is rapid, and the demand for land resources is increasing with the rapid development of cities. However, limited land resources are becoming an important limiting factor for urban development. Therefore, the development and utilization of underground space is the mainstream trend of urban development, especially the construction of subway has become a hot direction of traffic development in major cities. The southeast coastal city of our country is a typical soft soil foundation. The engineering geological condition is complex, the construction is difficult and the construction safety hidden danger is great. Therefore, it is of great practical significance to study the deformation of deep foundation pit support structure of subway station in soft soil area. Based on the deep foundation pit engineering of Liangxi Bridge Metro Station on Wuxi Metro Line 2, this paper studies the stability of deep foundation pit and deformation law of its enclosure system by using the method of field monitoring and numerical analysis. The main works are as follows: combining with the special hydrogeological conditions in the soft soil area, the stress and deformation theory of the excavation of the soft soil site is studied, and the mechanism and law of the deformation of the deep foundation pit are emphatically discussed. The main factors influencing the deformation of deep foundation pit enclosure are analyzed, and the space-time effect of deep foundation pit deformation is discussed. The results show that in the excavation and retaining process of foundation pit, the vertical unloading acting on the excavating surface and the horizontal unloading acting on the retaining surface of the retaining structure make the stress and deformation of the retaining structure change with the change of time and space. That is, space-time effect runs through the whole process of deep foundation pit excavation, and the space-time effect of soft soil site foundation pit engineering is more significant. Hydrological and engineering geological conditions, surrounding environment, type of supporting system, design and construction scale of deep foundation pit are the main factors influencing deformation of retaining structure of foundation pit. Based on the surrounding environment and supporting scheme of the railway station of Liangxi Bridge, the construction monitoring scheme of the foundation pit is established, the force and deformation of the supporting system of the foundation pit are monitored in real time, and the regularity of the measured data is studied. In this paper, the horizontal displacement of supporting structure, the axial force change of bracing system and the variation of ground surface settlement around foundation pit with excavation depth and time during foundation pit construction are studied. From the analysis of the monitoring data, it can be seen that the bracing system and the supporting structure play an important role in controlling the deformation of the foundation pit, and the horizontal displacement of the retaining wall and the surface settlement around the wall are all less than the control value. Due to the rheological characteristics of soft soil site, the space-time effect of foundation pit enclosure deformation is particularly significant. The numerical analysis model is established to simulate the whole process of deep foundation pit excavation, and the stress and deformation characteristics of retaining structure are analyzed by FLAC3D software, and the horizontal displacement and ground subsidence of deep foundation pit enclosure are discussed. The field monitoring data verify the rationality and reliability of the numerical simulation model.
【学位授予单位】：湖南工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU753
本文编号：2422567
[Abstract]:The economic development in the eastern coastal areas of China is rapid, and the demand for land resources is increasing with the rapid development of cities. However, limited land resources are becoming an important limiting factor for urban development. Therefore, the development and utilization of underground space is the mainstream trend of urban development, especially the construction of subway has become a hot direction of traffic development in major cities. The southeast coastal city of our country is a typical soft soil foundation. The engineering geological condition is complex, the construction is difficult and the construction safety hidden danger is great. Therefore, it is of great practical significance to study the deformation of deep foundation pit support structure of subway station in soft soil area. Based on the deep foundation pit engineering of Liangxi Bridge Metro Station on Wuxi Metro Line 2, this paper studies the stability of deep foundation pit and deformation law of its enclosure system by using the method of field monitoring and numerical analysis. The main works are as follows: combining with the special hydrogeological conditions in the soft soil area, the stress and deformation theory of the excavation of the soft soil site is studied, and the mechanism and law of the deformation of the deep foundation pit are emphatically discussed. The main factors influencing the deformation of deep foundation pit enclosure are analyzed, and the space-time effect of deep foundation pit deformation is discussed. The results show that in the excavation and retaining process of foundation pit, the vertical unloading acting on the excavating surface and the horizontal unloading acting on the retaining surface of the retaining structure make the stress and deformation of the retaining structure change with the change of time and space. That is, space-time effect runs through the whole process of deep foundation pit excavation, and the space-time effect of soft soil site foundation pit engineering is more significant. Hydrological and engineering geological conditions, surrounding environment, type of supporting system, design and construction scale of deep foundation pit are the main factors influencing deformation of retaining structure of foundation pit. Based on the surrounding environment and supporting scheme of the railway station of Liangxi Bridge, the construction monitoring scheme of the foundation pit is established, the force and deformation of the supporting system of the foundation pit are monitored in real time, and the regularity of the measured data is studied. In this paper, the horizontal displacement of supporting structure, the axial force change of bracing system and the variation of ground surface settlement around foundation pit with excavation depth and time during foundation pit construction are studied. From the analysis of the monitoring data, it can be seen that the bracing system and the supporting structure play an important role in controlling the deformation of the foundation pit, and the horizontal displacement of the retaining wall and the surface settlement around the wall are all less than the control value. Due to the rheological characteristics of soft soil site, the space-time effect of foundation pit enclosure deformation is particularly significant. The numerical analysis model is established to simulate the whole process of deep foundation pit excavation, and the stress and deformation characteristics of retaining structure are analyzed by FLAC3D software, and the horizontal displacement and ground subsidence of deep foundation pit enclosure are discussed. The field monitoring data verify the rationality and reliability of the numerical simulation model.
【学位授予单位】：湖南工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU753
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