冻融循环条件下岩石加卸荷力学特性研究  

Loading and Unloading Mechanical Characteristics of Rock under Freezing-thawing Cycles

作　　者：陈招军 王乐华[2,3] 王思敏[4] 李洁[3] 徐义根[3] 向力[3] 

机构地区：[1]中建三局第一建设工程有限责任公司,武汉430040 [2]三峡地区地质灾害与生态环境湖北省协同创新中心,湖北宜昌443002 [3]三峡大学三峡库区地质灾害教育部重点实验室,湖北宜昌443002 [4]陕西省水利电力勘测设计研究院,西安710001

出　　处：《长江科学院院报》2017年第1期98-103,共6页Journal of Changjiang River Scientific Research Institute

基　　金：水利部公益性行业科研专项经费项目(201401029)

摘　　要：为了探究冻融损伤后岩石加卸荷力学特性,以砂岩为研究对象,对经历不同冻融循环次数的2种含水率砂岩进行加卸荷试验。研究结果表明:冻融作用后,砂岩受到损伤,在加卸荷作用下,裂纹的扩展方向改变,发育程度加剧,且在饱和组砂岩中表现明显;从裂纹的扩展方向和破裂面角度来看,加载状态下砂岩以剪切破坏为主,卸载状态下以张拉和剪切破坏为主;加载条件下,冻融作用对砂岩造成的损伤反映出砂岩的峰值强度损失和弹性模量损失逐渐增大,且饱和砂岩较天然砂岩略大;卸荷条件下,各循环次数砂岩卸荷变形模量与卸荷当量之间的变化规律基本一致,当卸荷当量约为80%时,变性模量下降显著,而卸荷当量保持一定时,卸荷变形模量随冻融循环次数增加而减小。另外设计的卸荷速率都较小,对变形模量影响不明显。试验结果可为寒区岩质边坡开挖工程提供借鉴。In order to study the mechani we carried out loading-unloading test on cal loading and unloading properties of rock after freezing-thawing damage, sandstone of two different moisture contents under different freezing-thawing cycles. The results show that sandstone was damaged under the action of loading and unloading after freezing and thawing. The crack propagation direction change saturated sandstones. From the point of view of d,and the development of cracks intensified, especially obvous in the crack propagation direction and the fracture surface angle, the sandstone was dominated by shear failure under loading condition and tensile and shear failure under unloading con- dition. The damage caused by freezing and thawing indicated that the loss of peak strength and elastic modulus of sandstone increased gradually, which was slightly larger in saturated sandstone than that in natural sandstone under loading condition. Under unloading condition, the variation regularities of the unloading deformation modulus and the unloading equivalent of sandstone with different cycle times were basically consistent. The deformation modulus decreased significantly when the unloading equivalent was about 80%. The unloading deformation modulus decreased with the increase of the freeze-thawing cycle times while unloading equivalent remained unchanged. In addition, the unloading rate was so small in this paper that the influence on the deformation modulus was not obvious. The test results provide reference for the excavation of rock slope in cold region.

关 键 词：砂岩 冻融循环 加卸荷试验 卸荷当量 变形模量 卸荷速率 

分 类 号：TV223[水利工程—水工结构工程]