循环荷载下弱膨胀土累积变形与动强度特性试验研究  

Accumulated deformation and dynamic strength properties of weak expansive soil under cyclic loading

作　　者：庄心善 赵汉文 陶高梁 王俊翔 黄勇杰 ZHUANG Xin-shan;ZHAO Han-wen;TAO Gao-liang;WANG Jun-xiang;HUANG Yong-jie(School of Civil Engineering,Architecture and Environment,Hubei University of Technology,Wuhan,Hubei 430068,China)

机构地区：[1]湖北工业大学土木建筑与环境学院,湖北武汉430068

出　　处：《岩土力学》2020年第10期3192-3200,共9页Rock and Soil Mechanics

基　　金：国家自然科学基金(No.51708190)。

摘　　要：弱膨胀土经防水保湿处理后可作为路基填土,而目前对其动力响应特性研究较少。为深入分析合肥地区弱膨胀土动力特性,利用GDS动静态真三轴仪对土体进行循环动荷载试验,研究了不同围压、固结应力比及动应力幅值对土体累积变形及强度特性的影响规律。依据试样在不同围压、固结应力比、动应力幅值下的累积变形,建立了弱膨胀土累积变形预测模型。根据应变速率将弱膨胀土累积应变曲线划分为稳定型、破坏型和临界型,并给出判别标准。分析了不同围压、固结应力比下弱膨胀土动强度变化规律,在固结应力比超过1.5时土体强度明显下降,动黏聚力c_d随循环破坏振次lg N_f增大呈线性减小,动内摩擦角φ_d随循环破坏振次增大略微减小。该试验结果可为相关工程提供基础数据与参考。Weak expansive soil after treatment with waterproof and moisturizing can be used as the highway subgrade filling, and studies on its dynamic response characteristics are few. For a thorough analysis of the dynamic properties of weak expansive soil in Hefei, a series of cyclic load triaxial tests was conducted. Considering the influence of confining pressure, consolidation ratio and dynamic stress amplitude on the weak expansive soil dynamic property, the tests obtained the development curves of the accumulated deformation and dynamic strength under different test conditions. Based on the accumulated deformation of samples under different confining pressures, consolidation ratios and dynamic stress amplitudes, a prediction model for accumulated deformation of weak expansive soils was established. The accumulated strain curves of expansive soils can be divided into plastically stable, critical and destructive types according to the strain rate, and the criteria for judging the cumulative strain of weak expansive soil was given. The dynamic strength of weak expansive soil under different confining pressures and consolidation ratios was analyzed. It was found that the dynamic strength of the soil decreased a lot when the consolidation ratio was over than 1.5;the dynamic cohesion c_d decreased with the increase of failure vibration, and the dynamic internal friction angle φ_d decreased slightly with the increase of failure vibration. Results obtained can provide basic data and reference for relevant projects.

关 键 词：膨胀土 循环荷载 固结应力比 累积变形 动强度 

分 类 号：TU443[建筑科学—岩土工程]