论文部分内容阅读
为研究水力压裂裂纹与层理弱面斜交时的裂纹扩展规律,利用复变函数和保角变换等推导得出任意方向裂纹面尖端的应力集中解答。根据最大拉应力准则,通过比较压裂裂纹面在原扩展方向和层理弱面处以及沿层理扩展的应力状态及相应抗拉强度,得出均质岩体区裂纹稳定扩展遇斜交层理时,即垂直最小地应力方向裂纹遇任意方向层理的扩展规律。建立表示裂纹转向层理弱面扩展难易程度指标,即临界强度比,该指标与地应力状态、层理和岩石基体强度以及层理方位有关,其值越小表示裂纹满足转向层理扩展条件时所对应的层理和岩石基体的抗拉强度比越小。通过对规律解析分析得出:临界强度比随第一、第二与第三主地应力差降低或层理弱面与裂纹面夹角变小而增大;随岩石基体强度降低或层理弱面和裂纹面交线与中间主地应力夹角变小而减小。将解析分析结果与实验数据进行对比验证,规律一致。
In order to study the law of crack propagation when the hydraulic fracturing cracks and the stratified face weakness, the stress concentration solution of crack tip in any direction is derived by using complex functions and conformal transformation. According to the maximum tensile stress criterion, by comparing the stress state and the corresponding tensile strength of the fractured crack surface in the original expanding direction and the stratified weak surface, , That is, the vertical minimum stress direction of the cracks in any direction of extension of law. The establishment of a parameter that indicates the ease of expansion of the weak face of the turning steering layer, that is, the critical strength ratio, which is related to the state of the ground stress, the stratification and the strength of the rock matrix and the bedding orientation, and the smaller value indicates that the crack meets the steering bedding expansion condition When the corresponding layer and the rock matrix tensile strength ratio is smaller. By analyzing the law, the critical strength ratio increases with the decrease of the stress difference between the first, the second and the third main strata, or the smaller the included angle between the weak strata and the crack surface. As the strength of the rock matrix decreases or the stratification is weak Surface and crackline intersection with the middle of the main stress angle smaller and smaller. Analytical analysis results and experimental data for comparison and verification, the same rule.