不同水力荷载路径下煤体微观渗流特征及宏观破坏研究  

Micro seepage characteristics and macro failure of coal under different hydraulic loading paths

作　　者：马国良 陈曦 范超男 葛少成 MA Guo-liang;CHEN Xi;FAN Chao-nan;GE Shao-cheng(College of Safety and Emergency Management Engineering,Taiyuan University of Technology,Taiyuan,Shanxi 030024,China)

机构地区：[1]太原理工大学安全与应急管理工程学院,山西太原030024

出　　处：《岩土力学》2023年第6期1779-1788,共10页Rock and Soil Mechanics

基　　金：国家自然科学基金(No.52174195,No.51704145);山西省基础研究计划(自由探索类)(No.20210302123122,No.20210302123103)。

摘　　要：为探究煤体在不同水力荷载路径下的微观渗流特征,通过CT三维重建技术,建立了基于煤体微观结构的双介质渗流模型,并设计了恒定速度加载(LP1)、常规脉动加载(LP2)和强加载缓卸载加载(LP3)3种水力荷载路径,进行了在不同循环荷载路径下的煤体注水渗流数值模拟试验。另外利用自行搭建的煤体注水装置,探究了3种荷载路径下的宏观损伤情况。结果表明:联通裂隙占孔裂隙结构的73.49%,是影响煤体渗流的主要因素,而孔径为9~23μm的孔隙是孤立孔隙中的主要部分,数量和体积占比均超过了50%;煤体内部孔裂隙结构和荷载路径对渗流速度和压力的分布特征具有重要影响。LP1沿注入方向平均渗流速度的波动较大,LP3则抑制效果明显,且LP3路径较LP1和LP2随时间有较大跨度。LP3的荷载路径相对于LP1具有脉动荷载的疲劳损伤效果,并且造成的损伤程度强于LP2。该研究可为煤体微观结构研究和煤层注水技术参数优化提供方向。To study the micro seepage characteristics of coal under different hydraulic load paths,a two-media seepage model based on the microstructure of coal is established through CT three-dimensional reconstruction technology.Three equivalent hydraulic loading paths are designed,i.e.,constant velocity loading(LP1),conventional pulsating loading(LP2),and fast-loading and slow-unloading loading(LP3).The numerical simulation tests of water injection seepage of coal under different cyclic load paths are carried out.In addition,the self-built water injection device of coal is used to explore the macro damage under three loading paths.The results show that the connected fractures account for 73.49%of the pore-fracture structure and are the main factor influencing coal seepage.The pores with a diameter of 9−23μm are the major part of the isolated pores,with the number and volume share exceeding 50%.The pore-fracture structure and loading path within the coal has an important influence on the seepage distribution characteristics of velocities and pressures.The average seepage velocity of LP1 fluctuates greatly along the intrusion direction,while the inhibition effect of LP3 is obvious,and the path of LP3 has a larger span over time than those of LP1 and LP2.Compared with LP1,the loading path of LP3 has the fatigue damage effect of pulsating load,and the damage degree is more severe than that of LP2.This research can provide directions for the study of coal microstructure and the optimization of technical parameters of coal seam water intrusion.

关 键 词：CT三维重建 渗流特征 煤层注水 孔裂隙结构 强加载缓卸载 

分 类 号：TD714[矿业工程—矿井通风与安全]