摘要
黄土地区采用热减湿工法加固基坑边坡具有潜在应用价值,科学评价高温减湿黄土的裂隙演化是验证该加固工法可行性的关键环节。利用自制试验装置,进行了不同初始干密度和初始含水率的非饱和黄土在50~200℃温度水平下的裂隙演化试验,观察了土样含水率和表层裂隙变化,通过试验图像处理定量分析了裂隙率r、裂隙总长L、分形维数D、裂隙平均宽度W等裂隙指标随温度的变化规律。分析结果显示:随着温度水平提高,r、L、D均有所提高,W变化不明显;初始干密度的提高使r、L、D明显减小,使W明显提高;初始含水率的升高使r、L、D、W显著提高。高温作用显著改变土体的起裂模式,100℃临界温度作用下土体的起始裂隙快速出现,这可能与高压水蒸气的不均匀挤压有关。高温极大加快裂隙演化进程,但超过100℃后,继续升温对裂隙演化的加速幅度不大。从断裂力学的角度分析了高温作用下黄土裂隙开裂和扩展的力学机制,揭示了高温黄土裂隙演化机制。基于基质吸力对裂隙演化的重要影响,建立了考虑高温的基质吸力公式,在一定程度上揭示了高温对基质吸力的显著影响。
The hot-drying method for strengthening slope of foundation pit in loess holds potential application value,and the scientific evaluation of high-temperature loess crack evolution is a key link to verify the feasibility of the hot-dry method for strengthening loess.In this paper,a self-made experimental device was used to conduct crack evolution experiments on unsaturated loess samples with different initial dry densities and initial water contents at different high temperatures,and the changes in water content and surface crack of the soil samples were observed.Cracking indicators such as crack rate r,total crack length L,fractal dimension D,and average crack width W were quantitatively analyzed through experimental image processing.The analysis results show that r,L,and D all increase as the high temperature level increases,while W does not change significantly;the increase of initial dry density significantly reduces r,L,and D and significantly increases W;the increase of initial water content significantly increases r,L,D,and W.High temperatures significantly altered the crack initiation pattern of the soils,and the initiation cracks of the soils appeared rapidly under the 100℃critical temperature.This may be related to the inhomogeneous extrusion of high-pressure water vapor.The high temperature greatly accelerated the fracture evolution process,but after exceeding 100℃,the acceleration of the fracture evolution was not significant.The mechanical mechanism of loess cracking and extension under high temperature is analyzed from the perspective of fracture mechanics,revealing the mechanism of high-temperature loess crack evolution.Considering the significant influence of matrix suction on crack evolution,a formula considering high temperature and matrix suction is established,highlighting the significant influence of high temperature on matrix suction to a certain extent.
作者
赵再昆
王铁行
张亮
金鑫
鲁洁
阮嘉斌
邢昱
ZHAO Zai-kun;WANG Tie-hang;ZHANG Liang;JIN Xin;LU Jie;RUAN Jia-bin;XING Yu(College of Civil Engineering,Xi’an University of Architecture and Technology,Xi’an,Shaanxi 710055,China;School of Civil and Architecture Engineering,Xi’an Technological University,Xi’an,Shaanxi 710021,China;Shaanxi Key Laboratory of Geotechnical and Underground Space Engineering,Xi’an University of Architecture and Technology,Xi’an,Shaanxi 710055,China)
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2024年第5期1297-1308,共12页
Rock and Soil Mechanics
基金
陕西省自然科学基础研究重点项目(No.2020ZJ-49)。
关键词
黄土
裂隙演化
高温
初始含水率
初始干密度
loess
fracture evolution
high temperature
initial water content
initial dry density
