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工程科学与技术:2021,53(4):45-52
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湿-载-热对粉质黏土持水性能的影响特征及预测模型
(1.三峡大学 三峡库区地质灾害教育部重点实验室 湖北 宜昌 443002;2.中南地质科技创新中心,湖北 武汉 430070)
Effect and Modeling of Wetting-Loading-Heating on Water Retention Capacity of Silty Clay
(1.Key Lab. of Geological Hazards on Three Gorges Reservoir Area, China Three Gorges Univ., Yichang 443002, China;2.Geological Sci. and Technol. Innovation Center of Central South China, Wuhan 430070, China)
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投稿时间:2020-07-29    修订日期:2020-12-18
中文摘要: 非饱和土的持水性能通常以土水特征曲线的变化规律来体现。荷载和温度等因素对土水特征曲线的重要影响已逐渐被认识,但综合考虑湿-载-热对土水特征曲线共同作用的研究鲜见报道,对其主导性影响因素的分析更为罕见。为了探究粉质黏土在湿-载-热共同作用下的持水性能,本文开展了在不同竖向应力和温度条件下粉质黏土的干湿循环实验,分析了各因素的影响机理、特征和重要性,并建立了反映多因素共同作用的预测模型。研究结果表明:1)随着竖向应力的增加,非饱和土的进气值增加、减湿率降低、干湿循环过程的滞回效果变强,且在各个温度下皆表现出相同的特征。2)对比在相同的竖向应力、不同温度下的实验曲线,发现在温度较高的状态下,土体的进气值相对略低。3)竖向应力对于土体持水性能的影响最大,但主要局限于低吸力阶段;干湿循环的作用排第2,且随着循环次数增加会快速衰减;温度的影响较小,且在吸力值或密实度较高时可忽略不计。4)基于Logistic曲线改进后的L模型比常用的V-G模型更适用于巴东粉质黏土的土水特征曲线拟合。综合研究结果得出:竖向应力引起特征值变化的根本原因在于内部孔隙结构的改变,进而导致持水性能产生差异;温度主要影响土体处于低应力低吸力状态时的持水性能;3种赋存条件对粉质黏土持水性能的影响程度呈竖向应力>干湿循环>温度分布;改进后的L模型可以有效反映粉质黏土在湿-载-热共同作用下的持水性能演变特征。
Abstract:The water-retention capacity of unsaturated soils is usually reflected by the variation law of soil-water characteristic curve. The important effects of load and temperature on soil-water characteristic curves have been gradually recognized, but the studies considering the combined action of wetting-loading-heating on soil-water characteristic curves are seldom reported, and the analysis of dominant influencing factors is rarer. In order to investigate the water holding capacity of silty clay under combined actions, the dry-wet cycling experiments of silty clay under different vertical stress and temperature conditions were carried out, and the influencing mechanism, characteristics and importance of each factor were analyzed. A prediction model reflecting the combined action of multiple factors was then established. The results show that: 1) With the increase of vertical stress, the air intake value of unsaturated soil increases, the moisture reduction rate decreases, and the hysteresis effect of the wet-dry cycle becomes stronger, which occurs at different temperatures; 2) Compared with the experimental curves under the same vertical stress and different temperatures, it is found that the air intake value of soil is slightly lower at higher temperatures; 3) Vertical stress has the greatest influence on water-retention capacity of soil, but it is confined to the low suction stage; the function of dry-wet cycle ranks second and decays rapidly with the number of cycles increasing; the influence of temperature is small and negligible when suction or density is high; 4) The improved L model based on Logistic curve is more suitable for fitting the soil-water characteristic curve of Badong silty clay than V-G model. In summary, the change of internal pore structure is the main cause of characteristic value change caused by vertical stress, which leads to the difference of water-retention performance; temperature mainly affects the water-retention capacity of soil mass in low stress and low suction stage; the influence of three storage conditions on soil-water capacity of silty clay is ordered as vertical stress>dry-wet cycle>temperature distribution; the modified L model can effectively reflect the evolution characteristics of water-retention capacity of silty clay under combined action of wetting-loading-heating.
文章编号:202000633     中图分类号:TU43    文献标志码:
基金项目:国家自然科学基金项目(51409149);中国地质调查局项目(DD20190716;0001212020CC60002)
作者简介:第一作者:陈勇(1980-),男,教授,博士.研究方向:非饱和土的本构关系及库岸滑坡成灾机理研究.E-mail:cyonger@126.com
引用文本:
陈勇,严可翔,苏剑,王世梅,谭建民.湿-载-热对粉质黏土持水性能的影响特征及预测模型[J].工程科学与技术,2021,53(4):45-52.
CHEN Yong,YAN Kexiang,SU Jian,WANG Shimei,TAN Jianmin.Effect and Modeling of Wetting-Loading-Heating on Water Retention Capacity of Silty Clay[J].Advanced Engineering Sciences,2021,53(4):45-52.