基于光滑节理模型的岩体水力压裂数值模拟

Numerical simulation of hydraulic fracturing of rock mass based on smooth joint model

水力压裂是许多工程中非常关注的问题,自然情况下的岩体由于经历反复的地质作用往往会形成大量的结构面,结构面的存在影响并制约着岩体的性质.基于颗粒离散元程序对页岩水力压裂进行了数值模拟,采用颗粒粘结模型及光滑节理模型分别模拟完整岩石与节理面,对比分析了完整岩石以及存在节理面的岩体在高压水作用下的裂缝扩展及分布规律.研究发现:对完整岩石进行水力压裂可以获得较为完整的裂缝,且裂缝基本上沿着平行于最大主应力的方向扩展.节理面的存在对页岩水力压裂裂缝的扩展具有诱导作用,数值模拟结果显示除了注水孔周边,裂缝基本上沿着节理面扩展.

Hydraulic fracturing is a ubiquitous phenomenon in many projects.Naturally,as a result of repeated geological tectonism,a lot of structural planes would appear in rock mass.Meanwhile,those structural planes would affect property and limit the strength of rock mass.This paper performs numerical simulation for studying the effect of hydraulic fracturing using discrete element method,adopting particlebonded model and smooth joint model to simulate intact rock and joint plane respectively.Based on simulation results,contrastive analysis of crack propagation and distribution regularities caused by injecting high pressure fluid into intact and jointed rock mass is conducted.Research results show that the hydraulic fracturing crack in intact rock mass is continuous and its propagation direction is parallel to the direction of maximum principal stress.Joint is an inducement for the propagation of the hydraulic fracturing crack.Simulation results indicate that except for the region near injecting hole,crack extends almost along the joint planes.