学术论文

      基于微裂纹发育特性的大理岩特征强度数值模拟研究

      Numerical simulation research on characteristic strength of marble based on development of microcrack

      摘要:
      为获取锦屏大理岩的特征强度及破坏过程中损伤演化规律,运用PFC3D模拟大理岩试样并进行单轴、三轴压缩试验,以微裂纹的形态和数量的变化特征来确定大理岩的起裂和损伤强度.当微裂纹数量为峰值强度下微裂纹数量的0.1%,认为出现初始损伤,此时应力为大理岩的起裂强度.单轴压缩试验中,从裂纹形态上观察,将出现基本破裂面的应力定义为损伤强度.三轴压缩试验中,从裂纹数量上观察,将出现裂纹非稳定增长阶段时的应力定义为损伤强度.分析不同阶段出现微裂纹的位置实现了对微裂纹的定位,分析不同模型微裂纹增长量的变化,实现了对微裂纹稳定和非稳定增长的界定,补充了声发射的不足.对比PFC3D模拟和实验室试验得出的大理岩的特征强度,两者特征强度曲线的拟合函数相近.这说明运用PFC3D模拟确定大理岩的起裂强度、损伤强度的方法是一种合理的方法,微裂纹的研究对揭示脆性岩石强度破坏机制具有重要意义.
      Abstract:
      To obtain the characteristic strength and damage evolution law of rocks,the 3D particle flow code (PFC3D) was used to simulate Jinping Ⅱ Yantang marble rock group samples.The uniaxial and triaxial compression tests were conducted,and the initial fracture strength and damage strength were determined from the variable characteristics of microcracks morphology and quantity.When the number of microcracks reached 0.1% of the total microcracks at the peak strength,it was indicated that the initial damage occurred and the stress was the initial fiacture strength.In the uniaxial compression tests,the stress corresponding to basic fracture surface was defined as damage strength based upon the shape of crack.Meanwhile,in the triaxial compression test,the stress corresponding to the non-steady phase of crack growth was defined as damage strength based upon the number of cracks.By comparing the stress features obtained from PFC3D numerical and experimental results,it was shown that the fitting function of stress curves were quite similar,which indicated that the PFC3D simulation was a reasonable approach to determine the initial fracture strength and damage strength of marble.The study on microcracks was also significant to reveal failure mechanisms of brittle rocks.
      作者: 黄丹 李小青
      Author: HUANG Dan LI Xiao-qing
      作者单位: 华中科技大学土木工程与力学学院,湖北武汉,430074
      刊 名: 岩土力学 ISTICEIPKU
      年,卷(期): 2017, 38(1)
      分类号: TU452
      在线出版日期: 2017年4月24日
      基金项目: 国家自然科学基金(No.51278391).This work was supported by the National natural Science Foundation of China