摘要
考虑翼形裂纹内渗透压和主裂纹连通部分渗透压对翼形裂纹尖端应力强度因子的影响,建立渗透压-应力作用下岩体压剪翼形裂纹模型,该模型引入翼形裂纹的折算长度l_(eq),将翼形裂纹尖端的应力强度因子K_Ⅰ视为远场应力作用下平直孤立翼形裂纹产生的应力强度因子K_Ⅰ^((1))和等效主裂纹(主裂纹和折算翼形裂纹对组成)产生的应力强度因子K_Ⅰ^((2))之和.针对不同的侧压系数和裂纹渗透压,建立渗透压-应力作用下翼形裂纹有限元分析模型,得出:在高渗透压作用下,随翼形裂纹扩展,翼形裂纹尖端拉应力集中区逐渐增大;侧向拉应力和高渗透压是导致翼形裂纹不稳定扩展的主要因素.通过理论模型和有限元分析对比发现:除翼形裂纹很短的情况外,考虑裂隙渗透压时翼形裂纹理论模型得到的应力强度因子普遍较小,而不考虑渗压时模型解和有限元解误差较少,可以认为理论模型得到的翼裂尖端无量纲应力强度因子与翼形等效裂纹长度关系曲线在走向和量值与有限元解基本上是吻合的.渗透压-应力作用下翼形裂纹模型的建立可为水力劈裂研究和矿井岩溶突水力学机理研究提供理论参考:
Considering the effect of hydraulic pressure on wing cracks and the connected part of main crack on the stress intensity factor at wing cracks tip, the compression-shear wing cracks model under the action of hydraulic pressure-stress is established firstly. With the equivalent crack length leq of wing crack is introduced, the stress intensity factor KI at wing crack tip is assumed to be the sum of two terms： one is the component KI^（1） for a single isolated straight wing crack of length, subjected to the externally applied stresses, the other is the component KI^（2） due to the stresses induced by the presence of the equivalent main crack composed of the main crack and the equivalent crack length subjected to the same external stresses. According to different side pressure coefficients and hydraulic pressures in cracks, the FEM model of wing crack under the action of hydraulic pressure-stress is also established. The result shows that, under the action of high hydraulic pressure, with the wing crack propagation, the tensile stress regions increases gradually; the high hydraulic pressure and lateral tensile stress together leads to the wing cracks propagation in a unsteady way. A comparative analysis of theoretical model and finite element analysis shows that, except for the very short wing crack, compared with the finite element analysis results, considering hydraulic pressure, the stress intensity factor obtained from theoretical model is small. Without considering the model solution and FEM solution, the error is very small. So the relation curves between normalized SIF at wing cracks tip and equivalent cracks propagation length obtained from theoretical model is in good accordance with that from FEM model in both trend and magnitude. The wing cracks theoretical model provides some academic bases and references for studying hydraulic fracture and disaster mechanism of Karst water bursting in mine.
出处
《采矿与安全工程学报》
EI
北大核心
2010年第3期370-376,共7页
Journal of Mining & Safety Engineering
基金
国家重点基础研究发展计划(973)项目(2007CB209400)
国家自然科学基金项目(50974059)
湖南省高校科技创新团队支持计划项目
关键词
岩石力学
翼形裂纹
渗透压
数值验证
有限元
rock mechanics
wing crack
hydraulic pressure
numerical verification
FEM
