• 论文
主办单位:煤炭科学研究总院有限公司、中国煤炭学会学术期刊工作委员会
白砂岩卸围压强度与损伤破坏特征
  • Title

    Strength and damage failure characteristics of white sandstone under unloading confining pressure

  • 作者

    王云飞焦华喆李震宿辉

  • Author

    WANG Yunfei 1 ,JIAO Huazhe 1 ,LI Zhen 1 ,SU Hui 2

  • 单位

    河南理工大学土木工程学院

  • Organization
    1. School of Civil Engineering,Henan Polytechnic University,Jiaozuo 454000,China; 2. School of Water Conservancy and Hydroelectric Power,Hebei University of Engineering,Handan 056002,China
  • 摘要

    为了探讨白砂岩卸围压强度变形特征,利用RMT岩石力学试验系统进行了常规三轴、恒轴压卸围压应力路径试验,分析了白砂岩卸围压强度、变形、稳定时间和损伤破坏特征。获得以下主要结论:相同初始围压下,卸围压速率越大,屈服段越小,相同卸围压速率下初始围压越大屈服特性越明显;相同初始围压下,随着卸围压速率的减小,白砂岩破坏时的轴向变形增大,表明脆性减弱而延性增强,破坏时的内部损伤越严重;随着卸围压速率的减小,同一初始围压下破坏时围压增加,围压降减小而围压比增大;初始围压越大白砂岩稳定时间越长,但随着卸围压速率的增大稳定时间迅速减小,卸围压速率达到1MPa/s时,初始围压对稳定时间的影响已很小,不同初始围压下单位围压稳定时间的减小规律基本一致,且受初始围压影响甚微;卸围压应力路径对白砂岩的黏聚力有弱化效应,而对内摩擦角有强化作用,卸围压速率越大内摩擦角越大,黏聚力越小;利用八面体剪应力,基于Mogi-Coulomb强度准则获得了白砂岩强度判别通式;卸围压应力过程中声发射振铃计数一直处于较低水平,在破坏之前没有渐进增长的变化过程,且最大声发射出现在应力峰值处,可知卸围压过程中岩样内部损伤发展缓慢,损伤的快速发展形成主控破裂面主要出现在峰值处,且破坏之前没有声发射渐增先兆,破坏突然;白砂岩发生典型单一破裂面的剪切破坏,且随着卸围压速率的增大,破裂角整体呈增大趋势。

  • Abstract
    In order to study the strength and deformation characteristics of white sandstone under unloading confining pressure,conventional triaxial tests and constant axial pressure and unloading confining pressure tests were carried out using RMT rock mechanics test system. The strength,deformation,stability time and damage characteristics of white sandstone were analyzed under unloading confining pressure. The main conclusions are as follows:under the same initial confining pressure,the yield stage decreases with the increase of unloading confining pressure rate,and the larger the initial confining pressure is,the more obvious the yield characteristic is. Under the same initial confining pressure,the axial deformation of white sandstone increases with the decrease of unloading confining pressure rate,which indicates that the brittleness decreases and the ductility increases and the internal damage becomes more serious during failure. With the decrease of unloading confining pressure rate,the confining pressure at failure increases,the confining pressure reduction decreases and the confining pressure ratio increases under the same initial confining pressure. The larger the initial confining pressure is,the longer the stability time of white sandstone is. However,with the increase of unloading rate,the stability time decreases rapidly. When the unloading confining pressure rate reaches 1 MPa / s,the influence of initial confining pressure on the stability time is very small. The reduction law of the unit confining pressure stability time is basically the same under different initial confining pressures,and it is little affected by the initial confining pressure. The stress path of unloading confining pressure weakens the cohesion of white sandstone, but strengthens the internal friction angle,the larger the unloading confining pressure rate is,the larger the internal friction angle is,the smaller the cohesion is. Based on Mogi-Coulomb strength criterion and octahedral shear stress,a general strength formula of white sandstone was obtained. In the process of unloading confining pressure,the number of acoustic emission ring is always at a low level,and there is no gradual increase process before failure,and the maximum ring counts occurs at the peak stress. The internal damage of rock sample develops slowly in the process of unloading confining pressure,and the rapid development of damage forms the main control fracture surface at the peak,and there is no gradual increase omen for acoustic emission,the failure suddenly occurs. The typical shear failure occurs in white sandstone with single fracture surface,and the fracture angle increases with the increase of unloading confining pressure rate.
  • 关键词

    白砂岩卸围压速率强度变形破坏特征

  • KeyWords

    sandstone;unloading confining pressure rate;strength;deformation;failure characteristics

  • 基金项目(Foundation)
    国家自然科学基金资助项目(U1604142);河北省自然科学面上资助项目(E2018402263);河南理工大学青年骨干教师资助项目(2016XQG-10)
  • DOI
  • Citation
    WANG Yunfei,JIAO Huazhe,LI Zhen,et al. Strength and damage failure characteristics of white sandstone under unloading confining pressure[J]. Journal of China Coal Society,2020,45(8):2787-2794.
  • 相关文章
  • 图表
相关问题

主办单位:煤炭科学研究总院有限公司 中国煤炭学会学术期刊工作委员会

©版权所有2015 煤炭科学研究总院有限公司 地址:北京市朝阳区和平里青年沟东路煤炭大厦 邮编:100013
京ICP备05086979号-16  技术支持:云智互联