不同干湿条件下中等膨胀土裂隙发展及作用机理分析  

Analysis of the crack development and mechanism of moderately expansive soil under different drying-wetting conditions

作　　者：周锐 王保田[1,2] 王东英 王斯杰 张福海[1] ZHOU Rui;WANG Baotian;WANG Dongying;WANG Sijie;ZHANG Fuhai(Key Laboratory of Geotechnical Mechanics and Dam Engineering,Ministry of Education,Hohai University,Nanjing 210098,China;Engineering Research Center of Dredging Technology Ministry of Education,Hohai University,Changzhou 213022,China;Suqian Port and Shipping Development Center,Suqian 223834,China)

机构地区：[1]河海大学岩土力学与堤坝工程教育部重点实验室,南京210098 [2]河海大学疏浚技术教育部工程研究中心,常州213022 [3]宿迁港航事业发展中心,宿迁223834

出　　处：《农业工程学报》2023年第21期98-107,共10页Transactions of the Chinese Society of Agricultural Engineering

基　　金：国家自然科学基金项目(51778211)。

摘　　要：为深入研究膨胀土在干湿循环作用下的裂隙发展规律,该研究以宿连航道工程中富含的中等膨胀土为研究对象,按照不同温度、干燥方式、干湿范围进行干湿循环试验,基于图像处理技术并结合SEM扫描电镜微观形貌,定量分析了膨胀土裂隙发展的温度与干湿效应。结果表明:裂隙发展受温度影响显著,从自然风干条件到烘箱干燥50℃,随着温度增加,裂隙指标逐渐增长;高温条件下裂隙的发育模式为先增长后拓宽,裂隙长度更早趋于稳定,而裂隙平均宽度仍会继续增长,并在含水率低于15%后出现0.08~0.17 mm的下降趋势;干湿循环是土体内部结构逐渐劣化,微观损伤不断累积的过程。虽然干湿前期试样的裂隙平均宽度受体缩效应影响,随干湿范围扩大出现部分下降趋势,而裂隙长度彼此接近,但随着干湿次数增加,裂隙指标极大值对应的干湿范围将逐渐由22%~33%向9%~33%转移;各温度、干湿范围作用下,试样裂隙指标的增加主要集中在前5次干湿循环,裂隙率、裂隙长度与平均宽度相较于未经过干湿循环的土体,分别增加了2.63%~11.56%,210.32~445.34 mm,0.39~0.83 mm;单位宽度分形维数相较于整体分形维数简化了干湿范围对于整体裂隙发育的影响,高温及大的干湿范围作用下的试样干湿后期形成的裂隙几何形态与网络分布更加复杂繁琐。研究成果基于非饱和土土力学相关理论,分析了中等膨胀土在不同干湿循环条件下裂隙发展的潜在机理,可为极端天气条件下膨胀土胀缩裂隙研究与地质灾害预防提供参考依据。Expansive soil is classified as clayey soil that possesses a significant amount of hydrophilic minerals,including montmorillonite and illite.Under climatic conditions such as rainfall or drought,expansive soils demonstrate pronounced characteristics of swelling or shrinkage.The alteration in volume frequently leads to an uneven distribution of the stress field,resulting in crack formation when the tensile stresses surpass the tensile strength.The presence of cracks in the soil can deteriorate its mechanical characteristics,hence leading to a range of engineering and geological issues.In road and bridge engineering,the existence of cracks can decrease the soil bearing capacity,which may cause foundation settlement and superstructure inclination.In slope engineering,cracks development can lead to the rapid infiltration of rainwater,which will accelerate the formation of sliding surfaces while decreasing slope stability.Meanwhile,compacted expansive soils are widely distributed in the field of engineering.Due to their unique mineral structure,they are more sensitive to environmental changes compared to general clay.Therefore,the development of cracks under repeated drying-wetting cycles deserves special consideration.To investigate the development mechanism of cracks in expansive soil under the influence of drying-wetting cycles,this study focuses on moderately expansive soil found in the Su-Lian waterway project.Drying-wetting cycles were conducted at different temperatures,various drying methods,and drying-wetting ranges.Quantitative analysis of crack development in moderately expansive soil was performed using image processing techniques and scanning electron microscopy(SEM).The following conclusions were drawn:the development of cracks is significantly influenced by temperature.From natural air-dried to 50℃,the crack indicators gradually increase with the rising drying temperature.Under high-temperature conditions,the development pattern of cracks is characterized by initial growth followed by widening.Crack l

关 键 词：土壤 裂隙 干湿循环 温度效应 分形维数 机理研究 

分 类 号：TU443[建筑科学—岩土工程]