摘要
为揭示动载作用下深埋巷道的横截面形状效应,制备了含5种不同孔洞形状(矩形(R)、圆形(C)、直墙拱形(S)、纵、横椭圆形(E_(∥)、E_(⊥)))的水泥砂浆类岩石材料试样,利用落锤冲击试验系统地开展了试样动力响应特征研究。从应变时程曲线、洞周裂纹扩展过程、破坏模式3方面讨论了孔洞形状的影响,并结合PFC2D对试样的动态抗压强度、细观开裂机制进行了分析。结果表明:相同的冲击荷载作用下,纵椭圆试样的极限应变最大。孔洞顶板宏观裂纹的起裂位置位于中部;矩形和直墙拱形孔洞试样底板处裂纹更易从角点位置向下扩展,而其他孔洞形状的试样则从底板中部向下扩展贯通。矩形、直墙拱形和横椭圆形孔洞试样的顶板以张剪复合破坏为主,而圆形和纵椭圆形试样顶板的张拉破坏更显著。纵椭圆、直墙拱、圆形、矩形、横椭圆试样的动态抗压强度依次降低,故纵椭圆形试样的抗冲击效果最好。冲击荷载作用初期,拉应力主要集中于孔洞顶板处,集中区域大小与孔洞上边界的横向跨度正相关;试样临近峰值应力时,拉应力由顶板向两侧扩散至整个试样。峰后纵椭圆和圆形孔洞试样的回弹模量与弹性模量基本一致,塑性变形较小,而其他孔洞试样具有较高的残余应变。
To reveal the cross-sectional shape effect of a deeply buried roadway under dynamic load,cement mortar rock-like material samples with five different hole shapes(rectangular,R,circular,C,straight wall arch,S,vertical,E_(∥),and horizontal ellipse,E_(⊥))were prepared,and the dynamic response characteristics of the samples were studied by using the drop weight impact test system.The influence of hole shape was discussed from three aspects:strain time history curve,crack propagation process around the hole,and failure mode.The dynamic compressive strength and meso-cracking mechanism were analyzed by PFC2D.The results showed that the ultimate strain of the specimen with E_(∥)was the largest under the same impact load.The crack initiation position of the hole roof’s macroscopic crack was in the middle.The cracks at the bottom of specimens with the R and S were more likely to extend downward from the corner point,while the other specimens extended downward from the middle of the bottom.The roof of R,S,and E_(⊥)specimens was dominated by tensile-shear composite failure.In contrast,the tensile failure of the roof of C and E_(∥)specimens was more significant.The dynamic compressive strength of E_(∥),S,C,R,and E_(⊥)specimens decreased sequentially,therefore,the E_(∥)specimen had the best impact resistance.During the initial dynamic loading stage,the tensile stress was mainly concentrated at the roof of the hole,and the concentrated area was proportional to the transverse span of the upper boundary of the hole.When the stress was close to peak,the tensile stress gradually diffused to both sides of the specimen.In the post-peak stage,the rebound modulus of the E_(∥)and C samples was close to the elastic modulus,the plastic deformation was small,while the other samples showed a higher residual strain.
作者
任富强
谷金泽
孙博
常远
REN Fu-qiang;GU Jin-ze;SUN Bo;CHANG Yuan(School of Civil Engineering,University of Science and Technology Liaoning,Anshan,Liaoning 114000,China;School of Mining Engineering,University of Science and Technology Liaoning,Anshan,Liaoning 114000,China)
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2024年第S01期654-664,共11页
Rock and Soil Mechanics
基金
国家自然科学基金项目(No.51974187)
辽宁省教育厅资助项目(No.JYTMS20230958)
关键词
孔洞形状
落锤冲击
开裂模式
动力特性
细观机制
hole shape
drop weight impact
cracking mode
dynamic mechanical properties
mesomorphic mechanisms
作者简介
第一作者:任富强,男,1992年生,博士,副教授,主要从事岩石力学和边坡稳定性方面的研究。E-mail:renfuqiang@ustl.edu.cn
