双向压缩条件下闭合裂隙岩体断裂破坏机制及渗透压环境判定准则  

Fracture failure mechanism of rock with closed crack and judging criterion of seepage pressure under biaxial compression

作　　者：蒲成志[1,2] 曹平[2] 张春阳[2,3] 付宗智[2,4] 

机构地区：[1]南华大学核资源工程学院,湖南衡阳421001 [2]中南大学资源与安全工程学院,湖南长沙410083 [3]武汉理工大学资源与环境工程学院,武汉430070 [4]长沙有色冶金设计研究院有限公司,湖南长沙411201

出　　处：《岩土力学》2015年第1期56-60,67,共6页Rock and Soil Mechanics

基　　金：国家自然科学基金资助项目(No.51174228);湖南省博士生科研创新项目(No.CX2012B072)

摘　　要：在研究双向压缩条件下压剪复合型裂纹应力分布特征及断裂破坏机制基础上,考虑渗透压对初始裂隙面上有效正应力的影响,提出高低渗透压环境的判定准则,并基于滑动裂纹模型理论及最大周向拉应力破坏准则,得到不同渗透压环境下初始裂隙尖端微裂纹起裂特征与规律。研究结果表明:压剪复合应力条件下,初始裂隙尖端发育微裂纹的最优倾角与裂隙面摩擦系数直接相关,随裂隙面摩擦系数的增大,最优初始裂隙倾角由45°起逐渐增大;低渗透压条件下,渗流场的存在使裂纹面摩擦系数发生弱化,进而使得最优初始裂隙倾角向45°靠近,而渗透压直接降低裂隙面上有效正应力且与裂隙倾角无关,其仅仅影响裂隙体材料的初裂强度;高渗透压条件下,初始裂隙面由压剪复合应力状态转化为拉剪复合应力状态,并在拉剪复合应力场作用下,尖端微裂纹起裂角随KI/KII的不断增大,由70.5°逐渐趋近于0°。On the basis of the fracture failure mechanism and stress distribution characteristics of compressive-shear rock cracks under biaxial compression, this paper theoretically examines the influence of seepage pressure on the effective normal stress of preexisting crack surface. Then, a judging criterion is proposed for determining whether the seepage pressure is higher or lower. It considers the stress state of the effective normal stress of preexisting crack surface. Finally, the cracking law and characteristic of microcracks, generated at the tips of preexisting crack with different seepage pressures, are studied using the maximum circumferential stress criterion and sliding crack model. The results show that the optimal inclination angle of preexisting crack（on which the initial cracking strength of fissure body is the minimum） is directly related to the frictional coefficient of preexisting crack surface under biaxial compression. The optimal inclination angle of preexisting crack increases from 45° with the increasing of frictional coefficient of preexisting crack surface. When the seepage pressure is lower, the frictional coefficient of preexisting crack surface is weakened because of presence of seepage field. Furthermore, the optimal inclination angle of preexisting crack is close to 45°. On the other hand, the seepage pressure directly is applied to the surface of preexisting crack. Therefore, it just influences the initial cracking strength of fissure body. When the seepage pressure is higher, the stress state changes from compression-shear to tension-shear on the surface of preexisting crack. Because of the action of tensile stress, the initial cracking angle of microcrack generating at the tip of preexisting crack increases from 70.5° to 0° with the increasing of the value of KI /KII.

关 键 词：渗透压 初始裂隙面摩擦系数 最优初始裂隙倾角 起裂角 软化系数 

分 类 号：TU452[建筑科学—岩土工程]