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

发布时间：2018-01-17 18:12

本文关键词：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　出处：《岩土力学》2015年01期 　论文类型：期刊论文

【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°。
[Abstract]:On the basis of studying the stress distribution characteristics and fracture failure mechanism of compression-shear composite crack under biaxial compression, considering the influence of osmotic pressure on effective normal stress on initial fracture surface, a criterion for judging high and low osmotic pressure environment is proposed. Based on the sliding crack model theory and the maximum circumferential tensile stress failure criterion, the initiation characteristics and rules of initial crack tip microcracks under different osmotic pressure conditions are obtained. The results show that: under compression and shear composite stress conditions. The optimum dip angle of microcracks developed at the tip of the initial fracture is directly related to the friction coefficient of the fracture surface. With the increase of the friction coefficient of the fracture surface, the optimal initial crack dip angle increases gradually from 45 掳to 45 掳. Under the condition of low permeability pressure, the friction coefficient of crack surface is weakened by the existence of seepage field, and the optimal initial crack inclination angle approaches to 45 掳. However, the osmotic pressure directly reduces the effective normal stress on the fracture surface and has nothing to do with the crack dip angle, which only affects the initial crack strength of the fissure body material. Under the condition of high permeability pressure, the initial fracture surface changes from compressive and shear composite stress state to tension and shear composite stress state, and under the action of tension and shear composite stress field, the crack initiation angle of microcrack at the tip increases with the increase of KI/KII. From 70.5 掳to 0 掳.
【作者单位】：南华大学核资源工程学院;中南大学资源与安全工程学院;武汉理工大学资源与环境工程学院;长沙有色冶金设计研究院有限公司;
【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)
【分类号】：TU452
【正文快照】： 1引言岩体中节理、裂隙等结构面的存在及其相互作用对岩体力学性能的影响显著,在地质体三向应力状态下,其能够很好地保持稳定性,但采矿等地下工程活动的存在,使得岩体三向应力状态进行重新分布,造成岩体结构内部的应力偏离平衡状态,应力调整过程中,岩体内部原生结构面将会发生

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