宁波软土深基坑时空效应分析及安全评价研究

发布时间：2018-04-23 03:27

本文选题：深基坑工程 + 现场监测　；参考：《宁波大学》2013年硕士论文

【摘要】：为了缓解城市用地困难和交通拥堵的压力，大力开发地下空间、建设轨道交通成为城市健康发展的必然趋势。在宁波市轨道交通建设过程中，车站基坑与明挖区间都需要进行大规模的地下开挖，这就牵涉到大量软土深基坑工程的问题。本文以宁波市轨道交通2号线一期工程汽车市场站~甬江北站区间C基坑为背景，对现场监测成果、软土深基坑的时空效应、地基土m值的反演分析以及深基坑工程安全评价进行了较为系统的研究，，主要内容包括以下几方面： 1.结合宁波市轨道交通深基坑工程实例，给出了相应的施工监测方案。根据现场监测数据，重点分析了墙体水平位移、支撑轴力、墙顶竖向位移、地表沉降、建筑物沉降与坑外水位的变化情况，研究了宁波软土地区深基坑的变形规律及受力特征。 2.针对软土地区深基坑开挖的时空效应现象，采用考虑时空效应的有限元法建立基坑工程有限元分析模型，探讨了墙体厚度、墙体入土深度、支撑水平间距、支撑预加轴力、支撑架设时间、开挖宽度等因素对地下连续墙内力与变形的影响，并提出了深基坑工程时空效应施工方法。 3.基于深基坑开挖施工的实测位移数据，利用位移反分析法对典型工况下地基土的m值进行了反演分析，并将优化反演结果与勘察报告提供值进行比较，给出了深基坑开挖涉及到的主要土层m值的建议值。 4.结合深基坑工程的实际工况，构建了相应的安全评价等级与安全评价指标，利用模糊综合评判法建立了深基坑工程的安全评价模型，并结合现场监测数据，对工程实例的安全状况进行定量评价。
[Abstract]:In order to alleviate the difficulty of urban land use and the pressure of traffic congestion, it is an inevitable trend for the city to develop underground space and build rail transit. In the process of railway construction in Ningbo station foundation pit and open excavation section need to be excavated on a large scale which involves a large number of soft soil deep foundation pit engineering problems. In this paper, based on the foundation pit of section C of the first phase project of Ningbo Rail Transit Line 2, the space and time effects of deep foundation pit in soft soil are analyzed. The inversion analysis of m value of foundation soil and the safety evaluation of deep foundation pit engineering are studied systematically. The main contents include the following aspects: 1. Combined with the example of deep foundation pit project of rail transit in Ningbo, the corresponding construction monitoring scheme is given. Based on the field monitoring data, the changes of horizontal displacement of wall, supporting axial force, vertical displacement of wall top, ground settlement, building settlement and water level outside the pit are analyzed, and the deformation law and stress characteristics of deep foundation pit in soft soil area of Ningbo are studied. 2. In view of the space-time effect phenomenon of deep foundation pit excavation in soft soil area, the finite element analysis model of foundation pit engineering is established by using the finite element method considering space-time effect, and the wall thickness, wall depth, horizontal support spacing and supporting pre-axial force are discussed. The influence of support erection time, excavation width and other factors on the internal force and deformation of underground continuous wall is discussed, and the construction method of space-time effect of deep foundation pit engineering is put forward. 3. Based on the measured displacement data of deep foundation pit excavation, the m value of foundation soil under typical working conditions is inversed and analyzed by using displacement back analysis method, and the optimized inversion results are compared with the values provided by the survey report. The suggested value of m value of the main soil layer involved in deep foundation pit excavation is given. 4. Combined with the actual working conditions of deep foundation pit engineering, the corresponding safety evaluation grade and safety evaluation index are constructed, and the safety evaluation model of deep foundation pit engineering is established by using fuzzy comprehensive evaluation method, and the monitoring data on site are combined. The safety condition of engineering example is evaluated quantitatively.
【学位授予单位】：宁波大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU473.2;TU447

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