苏立君,赵 茜 ,刘 华 ,钱文君 ,何江涛 ,杨金熹
AuthorsHTML:苏立君 ^{1, 2, 3}，赵 茜 ⁴ ，刘 华 ^{4, 5}，钱文君 ⁴ ，何江涛 ⁴ ，杨金熹 ⁴
AuthorsListE:Su Lijun,Zhao Qian,Liu Hua,Qian Wenjun,He Jiangtao,Yang Jinxi
AuthorsHTMLE:Su Lijun^{1, 2, 3}，Zhao Qian⁴，Liu Hua^{4, 5}，Qian Wenjun⁴，He Jiangtao⁴，Yang Jinxi⁴
Unit:1. 中国科学院水利部成都山地灾害与环境研究所，成都 610041；
2. 中国科学院青藏高原地球科学卓越创新中心，北京 100101；
3. 中国科学院大学，北京 100049；
4. 西安建筑科技大学土木工程学院，西安 710055；
5. 陕西省岩土与地下空间工程重点实验室，西安 710055

Unit_EngLish:1. Institute of Mountain Hazards and Environment，Chinese Academy of Sciences，Chengdu 610041，China；
2. Center for Excellence in Tibetan Plateau Earth Sciences，Chinese Academy of Sciences，Beijing 100101，China；
3. University of Chinese Academy of Sciences，Beijing 100049，China；
4. School of Civil Engineering，Xi’an University of Architecture and Technology，Xi’an 710055，China；
5. Shaanxi Key Laboratory of Geotechnical and Underground Space Engineering，Xi’an 710055，China

Abstract_Chinese:为定量分析原状黄土的胀缩变形特性及裂隙形态演化规律，从黏黄土、黄土和砂黄土区域选择西安、延安 和米脂黄土进行颗粒分析、电镜扫描(SEM)与干湿交替试验，量测干湿过程中试样的轴向、径向变形，利用 PCAS 软件对裂隙照片进行矢量化处理并提取各项裂隙形态学参数．结果表明：干湿交替过程中三地黄土试样的体胀程度 逐渐增大，胀缩变形均以轴向变化为主，尺寸效应及干湿条件是导致及加剧试样变形各向异性的重要条件．三地黄 土表面裂隙的裂隙率、总长度、裂隙条数、块区面积及块区长宽比均随干湿交替次数的增加而逐渐增大．随地域由 南向北延伸(西安—延安—米脂)，黄土细粒含量逐渐减少，粗粒含量逐渐增多，骨架结构由集粒镶嵌排列向粗粒直 接接触变化，各项裂隙参数逐渐减小，裂隙网络形态由多边类圆形向规则窄长的四边形变化，裂隙达到稳定状态所 需时间缩短．楔体状裂隙由试样边缘向中心呈放射状生长，距边缘一定距离处近垂直向的裂隙开始横向延伸并相互 连接，内部贯通成一分界面，导致表层破碎土体剥落．利用 Boltzmann 生长模型可描述裂隙缓慢发育、快速增长、 滞缓发展的三阶段生长过程，为预测裂隙发展趋势提供参考．
Abstract_English:To quantitatively analyze the swelling and shrinkage behaviors and evolution law of crack morphology of undisturbed loess，in this study，we collected vertical samples representing clayey loess，loess，and sandy loess from Xi’an，Yan’an，and Mizhi，respectively，and then investigated these samples by particle size distribution tests，scanning electron microscopy(SEM)，and wetting-drying cycle tests. By measuring the axial and radial de\u0002formations of the specimens during wetting-drying and employing PCAS software to vectorize photos of the fissures， we obtained the complete swelling-shrinkage curves and morphological characteristics of the cracks. We found that theswelling and shrinkage of the loess samples occurred mainly in the axial direction in the Xi’an，Yan’an，and Mizhi loess，which indicates that size effect and dry-wet cycle are the important conditions that lead to the deformation ani\u0002sotropy of the sample，and can even aggravate the degree of anisotropy. The structural parameters of the surface cracks，including the porosities(crack area as a percentage of the image)，total length and number of cracks，and area and aspect ratio of the aggregates gradually improved with increases in the tines of dry-wet cycle number. As its geographical location varied from south to north，the fine-particle content of loess decreased and the coarse-particle content gradually increased；the skeleton structure changed from aggregate interlocking to coarse-particle direct con\u0002tact. Moreover，we found the degree of swelling of the loess samples increased，above crack parameters gradually decreased，shape of the crack network changed from multilateral circular to a regular and slender square shape，and time required for the cracks to reach a stable state shortened. Cracks of increasingly narrow width radiated from the edges of the samples to the centers and extended from the near vertical direction to the transverse direction. At a cer\u0002tain distance from the edge，the cracks were interconnected to form a splitting surface，which would cause a surface\u0002loess spalling hazard. The Boltzmann growth model can be used to describe the three-stage development mechanism of the cracks，which includes the phases of slow growth，rapid expansion，and sluggish development，and it can serve as a reference for predicting the development trend of cracks.
Keyword_Chinese:原状黄土；粒度组成；干湿交替；变形；裂隙
Keywords_English:undisturbed loess；particle size composition；wetting-drying cycle；deformation；crack

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