基坑支护的优化设计与应用研究

发布时间：2018-08-29 17:17

【摘要】：我国深基坑开挖与支护工程始于上世纪80年代。随着城市高层建筑的不断发展,基坑开挖的深度不断增加,最深达20-30米。基坑开挖与支护涉及到岩土工程、结构工程和排水工程等等,是一门综合性学科。在基坑开挖过程中要考虑众多因素影响：基坑支护方案的选择、基坑支护结构力与位移的变化、基坑排水、基坑周边环境建筑物沉降发展等等,解决以上问题是确保工程建设安全、经济、科学的根本保证。本文结合苏州交通银行大厦基坑开挖与支护工程,开展了基坑支护方案选择、基坑支护结构力与位移变化、基坑地下水控制等方面问题的研究,得到以下结论： 1.针对基坑岩土体参数条件、开挖深度和周边建筑物分布情况,提出了基坑支护的三种可行性方案。 2.通过分析基坑支护方案优选的影响因素,提出各评价参数的转化计算方法,建立了基坑支护方案选择的多属性决策模型。通过计算得出了排水+止水帷幕方案是苏州交通银行大厦基坑支护的首选方案的结论。 3.在弹性地基梁计算理论的基础上,考虑桩-土相对位移影响,根据支护桩水平支撑的设置情况将基坑的开挖分解为不同阶段,结合初参数法推导得出了开挖过程中支护桩水平位移、转角位移、弯矩和剪力沿桩身分布的计算公式。 4.理论分析了基坑抗突涌和抗稳定渗流的基本条件,并结合苏州交通银行大厦工程的基坑参数条件进行了这两方面问题的验算。 5.根据基坑降水的理论计算方法进行了苏州交通银行大厦基坑工程降水的设计计算,确保承压水和微承压水的降水井布置数量和口径都能满足要求。 6.通过理论分析,得到了水土合算、水土分算和考虑地下水形成渗流三种情况下的水压力计算公式,进一步分析推到得出了考虑渗透水影响情况下支护桩位移与力的计算公式。并根据基坑现场深层水平位移的监测数据进行理论计算与现场实测的对比分析,进一步验证了理论分析的正确性。 7.进行了基坑周边土体深层位移、周边道路沉降、支撑轴力、立柱沉降、圈梁水平位移、圈梁沉降、驳岸水平位移、周边建筑物沉降和地下地下水位变化的监测,分析总结出各参数在基坑开挖过程中的变化规律。
[Abstract]:The excavation and support of deep foundation pit in China began in 1980's. With the continuous development of urban high-rise buildings, the excavation depth of foundation pit is increasing, the deepest is 20-30 meters. Excavation and support of foundation pit involves geotechnical engineering, structural engineering and drainage engineering, etc. It is a comprehensive subject. In the process of foundation pit excavation, many factors should be considered: the selection of foundation pit support scheme, the change of the force and displacement of foundation pit support structure, the drainage of foundation pit, the settlement and development of surrounding buildings, and so on. Solving the above problems is the fundamental guarantee to ensure the safety, economy and science of engineering construction. Based on the excavation and support engineering of Suzhou Jiaotong Bank Building, this paper studies the selection of foundation pit support scheme, the change of foundation pit support structure force and displacement, and the underground water control of foundation pit. The conclusions are as follows: 1. According to the parameter condition of rock and soil, the depth of excavation and the distribution of surrounding buildings, three feasible schemes of foundation pit support are put forward. Based on the analysis of the factors affecting the optimal selection of foundation pit support schemes, a method for calculating the conversion of evaluation parameters is proposed, and a multi-attribute decision model for the selection of foundation pit support schemes is established. Through calculation, it is concluded that the drainage curtain scheme is the first choice for foundation pit support of Suzhou Jiaotong Bank Building. 3. On the basis of the calculation theory of elastic foundation beam, considering the influence of pile-soil relative displacement, the excavation of foundation pit is decomposed into different stages according to the setting of horizontal support of supporting pile. Combined with the initial parameter method, the formulas for calculating the horizontal displacement, angular displacement, bending moment and shear force distribution along the pile body during excavation are derived. The basic conditions of resisting outburst and steady seepage of foundation pit are analyzed theoretically, and the checking calculation of these two problems is carried out in combination with the parameters of foundation pit of Suzhou Jiaotong Bank Building. Based on the theoretical calculation method of foundation pit dewatering, the design and calculation of foundation pit dewatering in Suzhou Jiaotong Bank Building are carried out to ensure that the number and caliber of dewatering wells in confined water and micro-confined water can meet the requirements. Through theoretical analysis, the calculation formulas of water pressure are obtained under the conditions of water and soil calculation, soil and water division and seepage formation of groundwater, and the formula of displacement and force of supporting pile considering the influence of permeable water is obtained by further analysis. According to the monitoring data of the deep horizontal displacement of the foundation pit, the theoretical calculation and the field measurement are compared and analyzed, which further verifies the correctness of the theoretical analysis. The deep displacement of soil around the foundation pit, the settlement of surrounding road, the settlement of supporting axial force, the settlement of column, the horizontal displacement of ring beam, the settlement of ring beam, the horizontal displacement of barge bank, the settlement of surrounding buildings and the change of groundwater level are monitored. The variation law of each parameter in excavation process is analyzed and summarized.
【学位授予单位】：南京大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU753

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