钱塘江引水入城工程狭窄基坑支护结构优化设计

发布时间：2018-10-25 15:49

【摘要】：随着河道工程、引水工程、地铁工程等加速发展,长条形基坑、狭窄基坑不断出现。在这类基坑工程中,基坑的宽深比往往较小,基坑两侧围护结构之间距离较近,极限状态时被动滑裂土楔体形状可能由经典库仑理论中的三角形变为梯形,此时应考虑土体宽度和相邻挡墙的影响。对这类问题目前一般仍然采用经典的库仑或朗肯理论计算被动土压力,对于被动区土体仍沿用半无限体的假定,显然对于狭窄基坑的情形并不适合。工程实践中发现,基坑的宽度越小,稳定性越好。目前的规范推荐的抗倾覆稳定安全系数计算公式不能反映基坑宽度的影响,造成狭窄基坑围护结构插入深度与宽基坑相同,基于弹性抗力法的内力变形计算方法也不能考虑狭窄基坑的空间效应,造成了狭窄基坑设计的较大浪费。本论文在总结国内外有关研究成果的基础之上,结合钱塘江引水工程实例,采用有限元分析方法,利用PLAXIS岩土分析软件对狭窄基坑进行全断面模拟,本文主要完成以下几个方面的工作： 1.分析介绍了基坑变形的特征、类型及控制机理。 2.考虑土体与支护结构的相互作用,建立土体与支护结构的全断面有限元模型,利用PLAXIS岩土分析计算软件对基坑的分步开挖进行二维数值模拟。 3.分析了狭窄基坑与常规宽大基坑在基坑变形、支护结构内力、土压力、基坑整体抗滑稳定性等方面的差别。 4.将数值模拟结果与监测数据进行对比分析,验证分析模型及参数选取的可靠性和合理性。
[Abstract]:With the rapid development of river engineering, water diversion engineering and subway engineering, long and narrow foundation pits are emerging. In this kind of foundation pit engineering, the ratio of width to depth of foundation pit is usually smaller, the distance between the two sides of the foundation pit is close, and the shape of the passive sliding soil wedge may change from the triangle in the classical Coulomb theory to the trapezoid shape in the limit state. The influence of soil width and adjacent retaining wall should be considered. At present, the classical Coulomb or Rankine theory is still used to calculate the passive earth pressure. The assumption that the soil mass in the passive zone is still semi-infinite is obviously not suitable for the case of narrow foundation pit. It is found in engineering practice that the smaller the width of foundation pit, the better the stability. The formula for calculating the safety factor of anti-overturning stability, which is recommended in the current code, cannot reflect the influence of the width of the foundation pit, resulting in the insertion depth of the retaining structure of the narrow foundation pit being the same as that of the wide foundation pit. The calculation method of internal force deformation based on elastic resistance method can not take into account the space effect of narrow foundation pit, which results in a great waste in the design of narrow foundation pit. On the basis of summing up the domestic and foreign research results, combined with the Qiantang River diversion project, the finite element analysis method and PLAXIS geotechnical analysis software are used to simulate the whole section of narrow foundation pit. This paper mainly completes the following aspects of the work: 1. The characteristics, types and control mechanism of foundation pit deformation are analyzed and introduced. 2. Considering the interaction between soil and supporting structure, a full-section finite element model of soil and supporting structure is established, and the two-dimension numerical simulation of excavation is carried out by using PLAXIS geotechnical analysis and calculation software. The differences between narrow foundation pit and conventional large foundation pit in deformation of foundation pit, internal force of supporting structure, earth pressure and overall stability of foundation pit are analyzed. 4. The numerical simulation results are compared with the monitoring data to verify the reliability and rationality of the model and parameter selection.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TV223;TV67

【参考文献】