泥炭质土K0固结不同开挖路径应力-应变关系研究  

An experimental study of the stress-strain relationship of different excavation paths for soft soil K0 consolidation

作　　者：阮永芬[1] 潘继强 胡经魁 闫明 郭宇航 RUAN Yongfen;PAN Jiqiang;HU Jingkui;YAN Ming;GUO Yuhang(Faculty of Civil Engineering and Mechanics,Kunming University of Science and Technology,Kunming,Yunnan 650500,China;Kunming Prospecting Design Institute of China Nonferrous Metals Industry Co.Ltd.,Kunming,Yunnan 650051,China;China Railway 20th Bureau Group No.5 Engineering Co.Ltd.,Kunming,Yunnan 650000,China)

机构地区：[1]昆明理工大学建筑工程学院,云南昆明650500 [2]中国有色金属工业昆明勘察设计研究院有限公司,云南昆明650051 [3]中铁二十局集团第五工程有限公司,云南昆明650000

出　　处：《水文地质工程地质》2023年第2期112-121,共10页Hydrogeology & Engineering Geology

基　　金：中铁二十局集团第五工程有限公司科研计划项目(CR2005-5-JS-2021-009)。

摘　　要：基坑开挖过程中不同部位的土体会因不同的卸荷力学行为而表现出动态的破坏特性。为研究基坑土体开挖过程中复杂的卸荷应力路径,利用TSZ-1S应力控制式三轴仪分别对湖相沉积的泥炭质土进行固结不排水及K0固结下的加、卸荷试验,并按侧向、轴向、轴侧向同时卸荷等不同卸荷条件制定试验方案,模拟基坑开挖过程中不同部位土体卸荷路径下的应力-应变曲线、卸荷剪切破坏时的强度及初始切线模量等的变化规律。试验结果表明:土体的应力-应变特性与应力路径密切相关,各路径下应力-应变曲线都近似呈双曲线型;卸荷剪切破坏时强度明显低于加荷破坏。对不同卸荷路径下初始切线模量(E_(i))的研究发现,E_(i)受侧向卸荷影响较大,卸荷后E_(i)有所提高,轴向卸荷对其影响较小。对各应力-应变曲线进行归一化处理,构建了考虑不同归一化因子的归一化方程,以该方程为基础对不同应力路径下的泥炭质土进行归一化处理,并对结果进行了验证,效果良好。本研究可为泥炭质土场地上基坑在不同卸荷路径下的变形参数和本构关系的研究提供参考。In the process of foundation pit excavation, the soil mass in different parts shows dynamic destruction characteristics due to diverse unloading mechanics. In order to study the complex unloading stress path in the foundation excavation, the TSZ-1S stress control triaxial compression apparatus is used to carry out the loading and unloading tests of the lacustrine sedimentary peat soil under the conditions of consolidation undrained and K0consolidation, respectively, and the test scheme is formulated according to different unloading conditions such as lateral, axial and axial lateral meantime unloading, so as to simulate the stress-strain curves of soil under different unloading paths in the foundation excavation and the variation laws of strength and initial tangent modulus under unloading shear failure. The test results show that the stress-strain characteristics of soil are closely related to the stress path, and the stress-strain curves under each path are approximately hyperbolic. The strength of unloading shear failure is significantly lower than that of loading failure. The study of initial tangent modulus E_(i) under different unloading paths shows that E_(i) is greatly affected by lateral unloading, E_(i)increases after unloading, and axial unloading has little effect on it. The stress-strain curves are normalized, and the normalization equation of peat soil considering different normalization factors is constructed. Based on this equation, the peat soil under different stress paths is normalized, and the results are verified. The results of this work can provide reference for the study of deformation parameters and constitutive relations of foundation pits on peat soil sites under different unloading paths.

关 键 词：泥炭质土 卸荷路径 K0固结 应力-应变 初始切线模量 归一化 

分 类 号：TU411.3[建筑科学—岩土工程]