冻融条件下卸荷损伤砂岩力学特性试验研究  

Experimental Study on Mechanical Properties of Unloading Damaged Sandstone under Freeze-Thaw Conditions

作　　者：杜威 胡习文 杨柱 丁欢 陈兴周[1] DU Wei;HU Xiwen;YANG Zhu;DING Huan;CHEN Xingzhou(Department of Architecture and Civil Engineering,Xi'an University of Science and Technology,Xi'an 710054,China;China Gezhouba Group Co.Ltd.Wuhan 430000,China;PowerChina Northwest Engineering Corporation Limited,Xi'an 710065,China)

机构地区：[1]西安科技大学建筑与土木工程学院,西安710054 [2]中国葛洲坝集团股份有限公司,武汉430000 [3]中国电建集团西北勘测设计研究院有限公司,西安710065

出　　处：《西北水电》2022年第5期128-132,144,共6页Northwest Hydropower

基　　金：国家自然科学基金(U1965107、51979218);陕西省自然科学基金(2018JM5118).

摘　　要：寒区陡高岸坡开挖卸荷岩体的冻融侵蚀作用严重影响着开挖边坡的长期稳定与安全。以某寒区边坡开挖卸荷岩体为对象,综合考虑开挖扰动与冻融循环侵蚀交互作用的室内试验方案,以卸荷量为损伤划分标准开展三轴卸荷损伤试验制备卸荷损伤岩样,随后进行冻融循环试验与再承载力学试验。结果表明:冻融循环作用引发卸荷损伤砂岩内部孔隙裂隙的进一步扩展,其再承载峰前应变增长速率明显加快,且峰前应变量随冻融次数的增加而降低;指数函数模型较好的描述了再承载峰值强度的劣化规律,其量值受到围压大小的控制;卸荷效应为冻融循环侵蚀提供了作用通道,冻融6次时卸荷损伤砂岩表观出现宏观裂纹,且随着冻融次数的增加而发生变形扩展,再承载破坏形态表现出冻融次数越多,破裂块体或破坏裂纹也随之增多。The freezing-thawing erosion of excavated rock mass on steep bank slope in cold region seriously affects the long-term stability and safety of the excavated slope.Taking the excavation of unloaded rock mass in a slope in a cold region as study object,based on the laboratory test scheme on the interaction between excavation disturbance and freezing-thawing cyclic erosion,the triaxial unloading damage test is carried out with the unloading quantity as the damage classification standard to prepare the unloading damaged rock samples,and then the freezing-thawing cyclic test and reloading mechanical test are carried out.The results show that the freezing-thawing cycle causes the further expansion of the pore cracks in the unloading damaged sandstone,and the growth rate of the pre-peak strain increases obviously,and the pre-peak strain decreases with the increase of the number of freezing-thawing cycles.Exponential function model well describes the deterioration law of peak strength of reloading,and its value is controlled by confining pressure.Unloading effect provides an action channel for freezing-thawing cyclic erosion.Macroscopic cracks appear in unloading damaged sandstone after 6 cycles of freezing-thawing,and deformation and expansion occur with the increase of the number of freezing-thawing.The failure mode of reloaded sandstone shows that the more cycles of freezing-thawing,the more fractured blocks or failure cracks.

关 键 词：开挖边坡 卸荷损伤 冻融循环 指数函数模型 破坏特征 

分 类 号：TU45[建筑科学—岩土工程]