Effects of dry-wet cycles on the mechanical properties of sandstone with unloading-induced damage  

作　　者：NAN Gan ZHANG Jiaming LUO Yi WANG Xinlong HU Zhongyi 

机构地区：[1]Faculty of Engineering,China University of Geosciences(Wuhan),Wuhan 430074,China

出　　处：《Journal of Mountain Science》2024年第10期3474-3486,共13页山地科学学报（英文）

基　　金：financially supported by the National Natural Science Foundation of China(42177166).

摘　　要：Sandstone is the fundamental material in various engineering and construction projects.However,the mechanical integrity of sandstone can be compromised by initial unloading damage resulting from activities such as engineering excavations.Furthermore,this degradation is further exacerbated under periodic dry-wet environmental conditions.This study investigated the effects of dry-wet cycles and unloading on the mechanical properties of jointed fine sandstone using uniaxial and triaxial compression tests.These tests were performed on rock samples subjected to varying unloading degrees and different numbers of dry-wet cycles.The results demonstrate that with an increase in the unloading degree from 0%to 70%,there is a corresponding decrease in peak stress ranging from 10%to 33%.Additionally,the cohesion exhibits a reduction of approximately 20%to 25%,while the internal friction angle experiences a decline of about 3.5%to 6%.These findings emphasize a significant unloading effect.Moreover,the degree of peak stress degradation in unloading jointed fine sandstone diminishes with an increase in confining pressure,suggesting that confining pressure mitigates the deterioration caused by dry-wet cycles.Additionally,as the number of dry-wet cycles increases,there is a notable decline in the mechanical properties of the sandstone,evidencing significant dry-wet degradation.Utilizing the Drucker Prager criterion,this study establishes a strength criterion and fracture criterion,denoted as σ_(1)(m,n) and K_(T)^(Ⅱ)(m, n), to quantify the combined impacts of dry-wet cycles and unloading on jointed fine sandstone,which provides a comprehensive understanding of its mechanical behavior under such conditions.

关 键 词：UNLOADING Dry-wet cycle Jointed fine sandstone Strength criterion fracture criterion Mechanical properties 

分 类 号：TU45[建筑科学—岩土工程]