填土宽高比及内摩擦角对刚性墙后有限土体主动滑裂面的影响研究

Study on the influence of fill aspect ratio and internal friction angle on the active sliding surface of finite soil behind rigid walls

摘要

刚性挡墙后有限宽度土体破坏模式不同于经典库仑理论，滑裂面的位置及形式是影响土压力计算的重要因素。通过研究有限土体主动破坏模式研究，为主动土压力理论研究提供依据。以TT模式为例，利用自制模型，开展无黏性土主动破坏试验，利用数字图像法对试验过程中的土体图像进行采集和分析，与数值模拟结果进行对比，研究有限土体主动滑裂面特征。结果显示：有限土体主动破坏滑裂面为经过墙踵的“折线”,滑裂面与宽高比、内摩擦角有密切关系。结果表明：(1)宽高比越小，滑裂面折线段数越多，土体起始破裂角越大，滑裂面逐渐变陡，有限土体临界宽高比n_cr=0.49。(2)内摩擦角越小，折线段数越多，滑裂面破裂角越小，有限土体临界内摩擦角稍大于43.1°。(3)有限土体主动土压力由滑裂面左侧“三角形”滑体产生，小于库仑土压力的梯形滑裂楔体土压力。填土宽高比、内摩擦角是影响有限土体破坏模式的重要因素，是界定墙后土体为有限或半无限状态不容忽视的考量指标。

Abstract

The failure mode of soil with limited width behind a rigid retaining wall differs from the classical Coulomb theory. Position and form of the slip surface are crucial factors affecting the calculation of earth pressure. This study investigates the active failure modes of limited soil to provide basis for the theoretical research on active earth pressure. Taking the TT mode as an example, the study uses a self-made model to conduct active failure tests on cohesion soil. The digital image method is employed to collect and analyze the soil images during the testing process, and the result are compared with numerical simulation result to study the of the active slip surface in limited soil. The result show that the active failure slip surface in limited soil is a “broken line” passing through heel of the wall, and the slip surface is closely related to the width-to-height ratio and the internal friction angle. The result indicate that:(1) The smaller the width-to-height ratio, the more segments the slip surface has, the larger the initial rupture angle of the soil, and the steeper slip surface becomes. The critical width-to-height ratio for limited soil is 0.49.(2) The smaller the internal friction angle, the more the slip surface has, and the smaller the rupture angle of the slip surface. The critical internal friction angle for limited soil is slightly greater than 43.1°.(3) The active earth pressure in limited soil is generated by the “triangular” sliding mass on the left side of the slip surface, which less than the earth pressure of the trapezoidal sliding wedge in Coulomb's theory. The width-to-height ratio and the internal friction angle of the fill are important factors affecting the failure mode of limited soil, and they are indispensable considerations for determining whether the soil behind the wall is in a limited or semi-infinite.

关键词

有限土体 / 模型试验 / 数值模拟 / 主动破坏 / 滑裂面

Key words

limited soil / model test / numerical simulation / active failure / slip surface

Author summay

刘三县(1987—), 男, 高级工程师, 学士, 主要从事岩土工程勘察、设计及科研工作。E-mail: [e-mail]

基金资助

湖南省自然科学基金青年项目(2022JJ40160)

岳阳市规划勘测设计院有限公司校企研发项目(2024430607002014)