层间错动带水力耦合抗剪强度特性演化规律研究  

Evolution of shear strength of interlayer dislocation zone underhydro-mechanical coupling conditions

作　　者：范雷[1] 余美万[1] 邬爱清[1] 向前 FAN Lei;YU Mei-wan;WU Ai-qing;XIANG Qian(Key Laboratory of Geotechnical Mechanics and Engineering of the Ministry of Water Resources,Changjiang River Scientific Research Institute,Wuhan,Hubei 430010,China)

机构地区：[1]长江科学院水利部岩土力学与工程重点实验室,湖北武汉430010

出　　处：《岩土力学》2023年第7期1959-1970,共12页Rock and Soil Mechanics

基　　金：国家自然科学基金项目(No.51927815,No.42277186);中央级公益性利研院所基本利研业务费项目(No.CKSF2021532/YT)。

摘　　要：层间错动带具有延伸规模大、物理力学性质较差等特点。水库蓄水后,水位抬升使层间错动带受到较大的水压力。在高水压力作用下,层间错动带的抗剪强度及其演化规律,尚待开展试验研究。采用新研发的HMSS-300型现场结构面水力耦合直剪试验系统,针对溪洛渡水电站的层间错动带进行了不同水压力-应力耦合作用下的直剪试验,探讨了层间错动带水力耦合作用下的抗剪强度特征及其变化规律。研究结果表明:水力耦合作用下,层间错动带抗剪断过程的剪应力-剪切位移曲线具有明显的峰值,法向位移随剪切位移的增加大多表现出先剪胀后剪缩的特征。层间错动带的有效内摩擦角随水压力的升高而降低,二者呈负指数关系;有效黏聚力也随水压力的升高而降低,二者同样呈负指数关系。在0~2.0MPa水压力条件下,层间错动带有效内摩擦角劣化程度为7%~22%,有效黏聚力的劣化程度为32%~93%,表明水压力的增加对层间错动带的有效黏聚力影响更加明显。在不同法向荷载-水压力耦合作用下层间错动带呈现出剪切滑移破坏模式与中、细角砾岩颗粒的剪断-滑移混合破坏模式。在水力耦合条件下,黏土矿物的软化、膨胀与水侵入层间错动的颗粒之间以及黏土矿物的结构单位层之间形成水分子层是导致层间错动带抗剪强度劣化的主要因素。The interlayer dislocation zone has the characteristics of large extension scale and poor physico-mechanical properties.After reservoir impoundment,the rise of the water level imposes greater water pressure on the interlayer dislocation zone.Under the action of high water pressure,the shear strength of the interlayer dislocation zone and its evolution law need to be studied.In this paper,the newly developed direct shear test system HMSS-300 is used to conduct the direct shear tests under different hydro-mechanical coupling conditions on the interlayer dislocation zone of Xiluodu Hydropower Station.The characteristics and variation law of shear strength of the interlayer dislocation zone under the hydro-mechanical coupling conditions are discussed.The test results show that under the hydro-mechanical coupling conditions,the shear stress-shear displacement curve of the shear strength of the interlayer dislocation zone has an obvious peak value.The normal displacements mostly show the dilation first and then shrinkage as the shear displacement increases.With the increase in water pressure,both the effective internal friction angle and the effective cohesion of the interlayer dislocation zone decrease in a negative exponential relationship.Under the water pressure of 0−2.0 MPa,the degradation degrees of the effective internal friction angle and the effective cohesion of the interlayer dislocation zone are 7%−22%and 32%−93%,respectively.It indicates that the increase of water pressure has a greater effect on the effective cohesion of the interlayer dislocation zone.Under the coupling action of normal load and water pressure,the interlayer dislocation zone presents a shear-slip failure mode and a mixed shear-slip failure mode of medium and fine breccia particles.Under the hydro-mechanical coupling conditions,the softening and swelling of clay minerals,and water molecular layers formed by the water intrusion into the interlayer dislocation particles and the structural unit layers of clay minerals are the main fact

关 键 词：层间错动带 水力耦合 现场直剪试验 抗剪强度 

分 类 号：TU452[建筑科学—岩土工程]