黏弹性地基中基坑开挖对邻近桩基变形影响的时域解

发布时间：2018-09-18 16:18

【摘要】：目前就软土基坑开挖卸荷对邻近桩基变形影响的研究一般是基于瞬时开挖工况,很少考虑时间效应对桩-土相互作用的影响,但实际工程中软土在开挖情况下具有较为明显的流变效应。从地基黏弹性角度出发,采用两阶段法研究了黏弹性地基中基坑开挖与邻近桩基相互作用的时域问题。第1阶段基于Boltzmann黏弹性模型推导出Mindlin时域解,用于分析黏弹性地基中基坑开挖引起的邻近桩基处的土体附加应力;第2阶段采用Pasternak地基模型分析桩基与黏弹性土体之间的相互作用,并求得考虑流变效应的桩基水平变形的简化时域解。最后,采用大型有限差分软件对相关工况进行数值模拟,并将数值模拟结果与简化时域解进行对比分析,得到了较好的一致性。此外,也针对Boltzmann黏弹性模型参数(体积模量、剪切模量、黏性系数)、桩径、基坑开挖深度、桩与基坑间距和基坑开挖尺寸进行了影响因素分析。分析结果表明,所得出的简化时域解能较好地反映基坑开挖对邻近桩基水平变形的影响,以及桩基变形随时间的发展趋势,可为相关实际工程提供一定理论依据。
[Abstract]:At present, the research on the influence of excavation and unloading on the deformation of adjacent pile foundation is based on the instantaneous excavation condition, and the influence of time effect on the pile-soil interaction is seldom considered. But in actual engineering, soft soil has obvious rheological effect under excavation. From the point of view of viscoelasticity of foundation, the time-domain problem of interaction between excavation of foundation pit and adjacent pile foundation in viscoelastic foundation is studied by using two-stage method. In the first stage, based on the Boltzmann viscoelastic model, the time-domain solution of Mindlin is derived, which is used to analyze the soil additional stress caused by excavation of foundation pit in viscoelastic foundation. In the second stage, Pasternak foundation model is used to analyze the interaction between pile foundation and viscoelastic soil, and the simplified time-domain solution of horizontal deformation of pile foundation considering rheological effect is obtained. Finally, a large finite difference software is used to simulate the related working conditions, and the numerical simulation results are compared with the simplified time-domain solution, and a good agreement is obtained. In addition, the influence factors of Boltzmann viscoelastic model parameters (volume modulus, shear modulus, viscosity coefficient), pile diameter, excavation depth, pile-to-pit spacing and excavation size are also analyzed. The analysis results show that the simplified time-domain solution can well reflect the influence of excavation on the horizontal deformation of adjacent pile foundation, and the development trend of pile foundation deformation with time, which can provide some theoretical basis for relevant practical engineering.
【作者单位】：上海理工大学环境与建筑学院;国土资源部丘陵山地地质灾害防治重点实验室;中国建筑科学研究院建筑安全与环境国家重点实验室;
【基金】：国家自然科学基金项目(No.41772331) 上海自然科学基金项目(No.15ZR1429400) 国土资源部丘陵山地地质灾害防治重点实验室课题(No.2015k005) 建筑安全与环境国家重点实验室课题(No.BSBE2015-01)~~
【分类号】：TU433;TU753

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