注浆孔壁劈裂判据及裂缝扩展的数值模拟

Splitting criterion of grouting borehole wall and numerical simulation of crack propagation

在进行现场注浆时,经常会遇到注浆孔与岩体裂隙不相交的情况,因此,很有必要讨论在一定注浆压力作用下,注浆孔周围岩层是否劈裂以及劈裂的方向,从而可以判断该劈裂裂缝扩展以后是否与岩体原有裂隙相贯通。这样有利于进行注浆理论分析、数值模拟等。文中在考虑地应力和不考虑地应力2种情况下,分别对注浆孔周围岩层的劈裂与否以及劈裂方向给出了判据,同时在劈裂情况下,通过对大型有限元软件ANSYS进行二次开发,应用6节点奇异等参元模型模拟了劈裂裂缝尖端应力场的奇异性,并引入应力强度因子,对劈裂裂缝的扩展进行了数值模拟,从而得到了劈裂裂缝的最终扩展长度。研究结果对注浆理论的研究以及实际注浆工程问题的解决都具有一定的参考价值。

Abstract： The situation that the grouting borehole doesn＇t intersect with natural fractures of rock masses is often met in practical grouting project. Hence, it＇s necessary to discuss whether the rock masses around borehole will split under the grouting pressure and the corresponding splitting orientation. After the splitting crack finishes propagation, we can estimate whether it will penetrate original fractures, and it＇s favorable for grouting theory analysis and numerical simulation and so on. According to this, the splitting criterion and splitting orientation are with and without considering ground stress, respectively. In the meantime, under the situation of splitting, the singularity of crack-tip＇s stress field is simulated by 6 nodes singular isoparametric element through secondary development of large-scale finite element analysis software-ANSYS. The stress intensity factor is introduced and the propagation of the splitting crack is simulated to obtain the final propagation length, which has significant guiding meaning to grouting theory and the practical grouting projects.