水压诱发裂缝拉伸与剪切破裂的理论模型研究

发布时间：2018-01-03 16:01

本文关键词：水压诱发裂缝拉伸与剪切破裂的理论模型研究　出处：《岩石力学与工程学报》2017年09期 　论文类型：期刊论文

【摘要】：基于断裂力学理论,分别研究水压诱发的拉伸与剪切破坏特征。在水压诱发拉伸破坏方面,建立考虑井筒影响的地应力与水压耦合下的射孔尖端裂缝应力强度因子计算方程,推演该条件下拉剪复合应力状态下的断裂准则以及临界水压和启裂角的计算式。运用该方法从理论上分析了井筒周围存在对称的2条裂纹时,启裂水压和角度受射孔倾角、射孔长度、井筒半径及主应力差的影响。研究结果表明,依据推演的拉剪复合型断裂准则计算得到的射孔启裂水压和角度与试验结果吻合良好。参数分析表明:随着射孔长度或井筒半径的增加,临界水压减小。在水压诱发剪切破坏方面,则根据裂纹面的应力状态,分别推导裂纹处于压剪闭合状态和压剪不闭合状态下,水压诱发剪切破坏的断裂准则,并考虑非奇异应力对剪切断裂的影响,进一步推导压剪闭合应力状态下发生剪切破坏的临界水压计算公式。
[Abstract]:Based on the theory of fracture mechanics, the characteristics of tensile and shear failure induced by water pressure are studied, respectively, in the aspect of tensile failure induced by water pressure. The calculation equation of stress intensity factor of perforation tip fracture considering wellbore influence is established under the coupling of in-situ stress and water pressure. The fracture criterion under the condition of pull-down shear composite stress and the formulas for calculating critical water pressure and crack initiation angle are derived. Using this method, the symmetric two cracks around the wellbore are theoretically analyzed. The water pressure and angle of crack initiation are affected by perforation inclination, perforation length, wellbore radius and principal stress difference. The calculated water pressure and angle of perforation based on the derived tension-shear fracture criterion are in good agreement with the experimental results. The parameter analysis shows that with the increase of perforation length or wellbore radius. The critical water pressure decreases. In the case of water pressure induced shear failure, according to the stress state of the crack surface, the fracture criteria of the water pressure induced shear failure are derived, respectively, when the crack is in the state of compression shear closure and the pressure shear failure is not closed. Considering the influence of nonsingular stress on shear fracture, the critical water pressure formula for shear failure under the condition of compressive shear closure stress is derived.
【作者单位】：大连理工大学土木工程学院岩石破裂与失稳研究所;西南石油大学油气藏地质及开发工程国家重点实验室;
【基金】：国家自然科学基金资助项目(U1562103) 国家重点基础研究发展计划(973)项目(2014CB047100) 中央高校基本科研业务费专项资金资助(DUT17LK35)~~
【分类号】：TU45
【正文快照】： 高水头压力作用下,岩体中的裂隙发生扩展并相互贯通,称之为水力压裂(劈裂)。水压诱发的裂纹扩展对许多岩体工程(如石油开采、水利水电、矿井突水防治、核废料地下储存、地下污染物运移、地热开发工程等,具有重要的理论意义和应用价值。一方面,水压力的存在可能给工程带来严重

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