| 控制高径比条件下崩岗土体的收缩开裂特性 |
| |
| 引用本文： | 王佳妮,张晓明,丁树文,王谦,聂道祥.控制高径比条件下崩岗土体的收缩开裂特性[J].农业工程学报,2021,37(21):134-142. |
| |
| 作者姓名： | 王佳妮 张晓明 丁树文 王谦 聂道祥 |
| |
| 作者单位： | 华中农业大学资源与环境学院，武汉 430070 |
| |
| 基金项目： | 国家自然科学基金（41771307；41201271）；国家重点研发计划课题（2017YFC0505302）；长江科学院开放研究基金资助项目（CKWV2017522/KY）；2020年湖北省大学生创新创业训练项目（S202010504045） |
| |
| 摘 要： | 崩岗土体的收缩开裂受到多种因素的影响。该研究为研究高径比对其影响，共设计10组高径比，通过定点拍照记录脱湿前与脱湿结束时的土体形态变化，结合数字图像处理技术进行定量分析，探讨在控制高径比条件下崩岗土体的收缩开裂规律。结果表明：1）崩岗4层土中，过渡层的裂隙性、径向收缩性能最强，砂土层最弱，两者之间的较大差异会严重破坏崩岗土体的稳定性与承载力，促使崩壁崩塌；2）高径比较小的试样裂隙发育显著，径向收缩不明显；高径比较大的试样无裂隙发育，径向收缩显著。其中，4层土由干缩开裂土样过渡至径向收缩土样的高径比具体临界值分别位于：0.147～0.160、0.160～0.183、0.160～0.183、0.134～0.147；3）当高径比相同时，即使高度、直径不一致，但其各裂隙参数、径向收缩率具备相似性，轴向收缩率随厚度的增加而增加；4)随高径比的增加，收缩含水率逐渐增大，开裂含水率逐渐减小，两者之间的差值可以表示脱湿过程中土体产生抗拉强度的大小。收缩开裂裂隙度、宽径比、径向收缩率随高径比的增加整体呈现增大的趋势，其余参数均呈现减小的趋势。其中，4层土中，过渡层的收缩开裂特性受高径比影响最显著，砂土层受影响程度最小。研究结果可为揭示崩岗崩塌机理提供科学依据。
|
| 关 键 词： | 裂隙 收缩 定量分析 崩岗 高径比 |
| 收稿时间： | 2021/6/8 0:00:00 |
| 修稿时间： | 2021/8/12 0:00:00 |
Shrinkage and cracking characteristics of Benggang soil under the condition of controlling height-diameter ratio |
| |
| Wang Jiani,Zhang Xiaoming,Ding Shuwen,Wang Qian,Nie Daoxiang.Shrinkage and cracking characteristics of Benggang soil under the condition of controlling height-diameter ratio[J].Transactions of the Chinese Society of Agricultural Engineering,2021,37(21):134-142. |
| |
| Authors: | Wang Jiani Zhang Xiaoming Ding Shuwen Wang Qian Nie Daoxiang |
| |
| Institution: | School of Resources and Environment, Huazhong Agricultural Universit, Wuhan 430070, China |
| |
| Abstract: | Abstract: Shrinkage and cracking of Benggang soil often occur and vary significantly in different soil layers during water evaporation. That is because there are the hydrophilic clay minerals (kaolinite and hydromica) in the special soil with stratification after natural geological evolution. This study aims to clarify the influence of height-diameter ratios on soil shrinkage and cracking characteristics. The Benggang soil was selected in the Wuli Town, Tongcheng County, Hubei Province of China. 10 groups of height-diameter ratio were then designed for the experiment. The soil samples were configured as supersaturated mud, where the water evaporation was accelerated using low-speed wind fans. The soil morphologies before and after dehumidification were characterized at a fixed position. Digital image processing was also utilized to carry out a quantitative analysis. Therefore, the shrinkage and cracking mechanism of Benggang soil were addressed under the condition of controlling the height-diameter ratio. The results are listed as follows. 1) There was the strongest radial shrinkage and cracks development in the transition layer, whereas, the weakest in the sandy layer among the four layers of Benggang soil. The transition and sandy layers were then defined as the lower soil adjacent to the soil layer in the vertical section. The less difference between the two soil layers was contributed to the stability and bearing capacity of Benggang soil, thereby relieving the collapse of the Benggang wall. 2) The samples with a smaller height-diameter ratio developed significant cracks, but the radial shrinkage was not outstanding. By contrast, there was no crack in the samples with a larger height-diameter ratio, but the radial shrinkage was significant. Among them, the specific critical values of the height-diameter ratio for the four soil layers during the transition from the drying cracking to radial shrinkage state were achieved, 0.147-0.160, 0.160-0.183, 0.160-0.183, and 0.134-0.147, respectively. 3) The crack parameters and radial shrinkage ratio were similar, but the axial shrinkage ratio increased as the thickness of the soil layer increased, particularly when the height-diameter ratio was the same, even though the height and diameter were different. More importantly, the crack morphology developed more complex from the topsoil to the transition layer, but the sandy layer remained unchanged. 4) The shrinkage water content gradually increased with the increase of height-diameter ratio, whereas, the crack water content gradually decreased. The difference between them was then represented by the tensile strength of soil during the dehumidification. Correspondingly, the degree of shrinkage and cracking, the width-diameter ratio, and the radial shrinkage ratio increased with the increase of the height-diameter ratio, whereas the rest parameters showed a decreasing trend. Therefore, there was the most significant influence of height-diameter ratio on the shrinkage and cracking characteristics in the transition layer, whereas, the least influence was found in the sandy layer. The finding can also provide strong theoretical support to reveal the collapse mechanism of Benggang soil for higher stability in construction projects. |
| |
| Keywords: | crack shrinkage quantitative analysis Benggang height-diameter ratio |
|
| 点击此处可从《农业工程学报》浏览原始摘要信息 |
| 点击此处可从《农业工程学报》下载免费的PDF全文 |
|
