摘要
为研究不同控制方式和卸荷应力路径下岩石节理失稳剪切强度特征,借助RDS-200型岩石节理剪切试验系统开展了2种控制方式和3种卸荷应力路径下的类岩石节理直剪试验。结果表明:(1)采用应力控制方式进行切向加卸载时,各剪切加卸载路径下,节理剪切应力-时间曲线多存在失稳跌落现象,剪切应力-位移曲线失稳后多表现为折线形式。(2)与采用应力控制方式进行切向加载的试样结果相比,采用位移控制方式进行切向加载、采用应力控制方式进行法向卸载并保持剪切应力恒定、采用应力控制方式进行法向卸载和切向加载、采用应力控制方式同时进行法向和切向卸载的试样失稳剪切强度均有所降低;节理黏聚力减小百分比平均值为36.07%,而内摩擦角变化范围仅在4.12%以内,所以黏聚力降低是节理失稳剪切强度降低的主要原因。(3)以采用应力控制方式进行切向加载试样的拟合摩尔-库仑公式为基准,位移控制方式或其他采用应力控制方式的加卸载应力路径下试样失稳剪切强度的相对误差平均值最大可达55.78%。经引入黏聚力修正系数k对摩尔-库仑准则进行修正后,相对误差平均值的最大值减小到5.23%,说明对经受位移控制方式或采用应力控制方式的其他加卸载应力路径的工程节理来说,进行黏聚力的折减修正是必要和可行的。研究结果对不同控制方式及卸荷应力路径下岩体节理剪切承载能力的准确估计具有一定参考价值。
In order to study the shear strength characteristics of rock-like material joints in different loading control modes and unloading stress paths,the direct shear tests of rock-like material joints in two loading control modes and three unloading stress paths were carried out by means of RDS-200 rock joint shear test system.The results show that:(1)when the stress control mode is used for shear test,it can be found that the joint shear stress-time curve mostly has the instability drop,and the shear stress-displacement curve is mostly in the form of broken line after instability in each shear stress loading and unloading path.(2)Compared with the results of the joints that experiencing shear loading in a stress control mode,the instability shear strength is reduced when the rock-like material joints are sheared in the following control mode and unloading stress paths including loading shear stress in a displacement control mode,unloading the normal stress in a stress control mode while keeping the shear stress constant,unloading the normal stress while increasing the shear stress in stress control modes,unloading both the normal stress and the shear stress in stress control modes.The average decrease percentage of cohesion is 36.07%,while the change range of internal friction angle is only 4.12%.Therefore,the decrease of cohesion is the main reason for the decrease of the joint instability shear strength.(3)Based on Mohr-Coulomb formula for joints experiencing the shear loading in a stress control mode,the average relative error of the instability shear strength of joints experiencing a shear loading in the displacement control mode or experiencing loading and unloading in other stress paths in the stress control mode can reach up to 55.78%.The maximum value of the average relative error can be reduced to 5.23%after the cohesion correction coefficient k is introduced to modify the Mohr-Coulomb formula,which shows that the reduction correction of cohesion is necessary and feasible for engineering joints that may expe
作者
孙杰豪
郭保华
程胜锦
田世轩
陈岩
SUN Jie-hao;GUO Bao-hua;CHENG Sheng-jin;TIAN Shi-xuan;CHEN Yan(School of Energy Science and Engineering,Henan Polytechnic University,Jiaozuo,Henan 454000,China;The Collaborative Innovation Center of Coal Safety Production of Henan Province,Henan Polytechnic University,Jiaozuo,Henan 454000,China;Jiaozuo Engineering Research Center of Road Traffic and Transportation,Henan Polytechnic University,Jiaozuo,Henan 454000,China)
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2024年第7期2061-2071,2116,共12页
Rock and Soil Mechanics
基金
国家自然科学基金(No.51904092)
河南省自然科学基金(No.202300410183)。
关键词
岩石力学
控制方式
应力路径
类岩石节理
直剪试验
剪切强度
rock mechanics
control mode
stress path
rock-like material joints
direct shear test
shear strength
