岩土力学 ›› 2024, Vol. 45 ›› Issue (8): 2421-2436.doi: 10.16285/j.rsm.2023.1371

• 基础理论与实验研究 • 上一篇    下一篇

高置换率散体材料桩-不透水桩组合型复合地基非线性固结解析研究

孙锦鑫1, 2，卢萌盟1, 2，刘干斌3   

  1. 1. 中国矿业大学 力学与土木工程学院，江苏 徐州 221116；2. 中国矿业大学 深部岩土力学与地下工程国家重点实验室，江苏 徐州 221116； 3. 宁波大学 岩土工程研究所，浙江 宁波 315211
  • 收稿日期:2023-09-13 接受日期:2023-10-10 出版日期:2024-08-10 发布日期:2024-08-12
  • 通讯作者: 卢萌盟，男，1979年生，博士，教授，主要从事软黏土力学与地基处理等方面的教学与研究工作。E-mail：lumm79@126.com
  • 作者简介:孙锦鑫，男，2000年生，硕士研究生，主要从事地基处理方面的研究工作。E-mail：TS22030055A31LD@cumt.edu.cn
  • 基金资助:
    国家自然科学基金（No. 52178373, No. 51878657）。

Nonlinear consolidation analysis for combined composite ground with high replacement ratio-granular columns and impervious columns

SUN Jin-xin1, 2, LU Meng-meng1, 2, LIU Gan-bin3   

  1. 1. School of Mechanics and Civil Engineering, China University of Mining and Technology, Xuzhou, Jiangsu 221116, China; 2. State Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining and Technology, Xuzhou, Jiangsu 221116, China; 3. Institution of Geotechnical Engineering, Ningbo University, Ningbo, Zhejiang 315211, China
  • Received:2023-09-13 Accepted:2023-10-10 Online:2024-08-10 Published:2024-08-12
  • Supported by:
    This work was supported by the National Natural Science Foundation of China (52178373, 51878657).

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摘要：

为加快固结排水速率并提高地基承载力，组合型复合地基加固技术被广泛应用于地基改良工程，而目前关于此类复合地基的非线性固结理论研究很少。通过对数模型来描述土体的非线性固结特征，并考虑桩-土压缩模量比随固结的变化，建立了散体材料桩-不透水桩复合地基非线性固结解析模型。此外，为减小研究高置换率复合地基固结时产生的计算误差，对传统假定进行修正，并引入新的流量连续性关系来考虑散体材料桩的固结变形。综合考虑散体材料桩井阻效应、桩体施工扰动效应和土体内径-竖向渗流，基于等应变假设和达西定律，推导了该模型的固结控制方程及其解析解。通过参数敏感性分析对复合地基非线性固结特性进行研究，分析了不同荷载形式下各参数对固结性状的影响。此外，与现有模型展开比较研究，并与实测数据进行对比分析，验证了该解答的正确性。结果表明：忽略散体材料桩的桩体固结变形会高估复合地基的固结速率，随着桩体置换率的增加，计算误差最大可达10.5%；当压缩指数Cc小于渗透指数Ckh(v)时，不考虑土体的非线性特征会低估地基固结速率；Cc/Ckv的变化对固结速率的影响很小，与Cc/Ckh相比可以忽略不计；施工场地布置越密集、桩-土压缩模量比越大、散体材料桩渗透系数越大或扰动区半径越小，均会导致地基固结加快。

关键词: 非线性固结, 复合地基, 散体材料桩, 不透水桩, 地基处理

Abstract:

 In order to enhance the ground strength and accelerate the consolidation rate, the technique of combined composite ground has been widely utilized in ground improvement projects. However, there are few theoretical investigations on the nonlinear consolidation behavior of this combined technique. To fill this gap, the logarithm models of are incorporated to describe the nonlinear consolidation characteristics of soils, then an analytical model for the nonlinear consolidation of composite ground with combined use of granular columns and impervious columns is established by accounting for the variation of the column-soil compression modulus ratio with consolidation. Further, the consolidation deformation of granular columns is considered by introducing a new flow continuity relationship. Based on the equal strain assumption and Darcy’s law, the governing equations and analytical solutions are then obtained with consideration of the well resistance of granular columns, disturbance effects of both impervious columns and granular columns and the coupled radial-vertical seepage within soil. Moreover, the present solutions under different loading schemes are adopted to investigate the influence of several crucial parameters on the nonlinear consolidation behavior of composite ground. Furthermore, the accuracy of the current model is verified by comparing it with the existing solutions and applying it to analyze two tests. The results reveal that ignoring column consolidation deformation leads to an overestimate of consolidation rate, with maximum error reaching up to 10.5% as the replacement ratio increases. Neglecting the nonlinearity will underestimate the consolidation rate when the soil’s compressive indices Cc are smaller than the permeability indices Ckh(v). Additionally, the variation of Cc/Ckv has little influence on the consolidation rate and can be ignored when compared with Cc/Ckh. Factors such as a denser construction site layout, a higher column-soil compression modulus ratio, a larger permeability coefficient, or a smaller smear zone area of granular columns will accelerate the consolidation of composite ground.

Key words: nonlinear consolidation, composite ground, granular column, impervious column, ground improvement

中图分类号: TU 470
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