基于格里菲斯准则的地下岩体天然裂缝分布的有限元模拟研究

地下沉积岩体一般非均质性很强，力学性质存在很大差异，并且在演化过程中由于深度、温度、围压等环境条件的差异以及后期可能发生的剥蚀、裂缝充填等改造作用的影响，使材料的力学性质发生改变。地下岩体的破裂也往往是在地质历史过程中经历了多期发育而最终形成。地下岩体的所有这些特点使裂缝分布预测的难度加大。针对这些特点，采用综合定量方法建立裂缝预测的数学模型，分析裂缝形成的影响因素，确定模型参数和数值模拟步骤，从而对裂缝发育概率和发育特点做出预测。最后介绍了一个在石油工业中应用的实例。

FINITE ELEMENT RESEARCH ON NATURAL FRACTURE DISTRIBUTION IN UNDERGROUND ROCKS ACCORDING TO GRIFFITH CRITERION

Generally,underground sedimentary stratum consists of several kinds of rocks,with very strong anisotropy and different mechanical property. Moreover,during evolution,the difference of depth,temperature,confined pressure,and the influence of filling,degradation,which probably happened after the fracture forming,make the mechanical property of underground sedimentary stratum changed. The cracking of underground sedimentary stratum is also multiphase in the course of geological history. All these characters of underground sedimentary stratum make it difficult to forecast the distribution of fracture. According to all these characters,comprehensive quantitative method is used to establish mathematic model,analyze the influent factors of cracking,and determine the parameters of model and the steps of modeling. Then the fracture developing probability and fracture characters are predicted. At last,a sample is introduced taking from petroleum industry.