冻融循环作用下单裂隙红砂岩损伤及压剪断裂研究  

Damage and Compression-Shear Fracture of Single Fractured Red Sandstone Under Freeze-Thaw Cycles

作　　者：李庆 LI Qing(China Railway Construction Group Corporation Limited,Beijing 100040,China)

机构地区：[1]中铁建设集团有限公司,北京100040

出　　处：《矿业研究与开发》2024年第5期157-165,共9页Mining Research and Development

摘　　要：针对西部寒区工程中冻融循环对裂隙岩石的作用,采用TDS-300型冻融试验机,对单裂隙红砂岩开展冻融循环试验,裂隙倾角分别为0°、45°和90°,循环次数设为0,20,40,60次。利用伺服万能试验机对冻融损伤后的红砂岩进行单轴压缩试验,并借助核磁共振技术(NMR)检测红砂岩冻融损伤特征。试验结果表明:随着冻融循环次数增加,红砂岩的弹性模量、质量、峰值强度以及孔隙度损伤变量呈现不同程度的增大。通过核磁共振技术,发现T2谱图面积随着冻融循环次数的升高而增大,同时小孔发育缓慢,中孔前期较后期发育迅速,而大孔数量增加最多。此外,冻融循环次数越大,NMR图中白色斑点由边缘越向中心扩散,损伤面积逐渐增大,向内部深入。基于断裂力学,建立冻融-荷载耦合作用下单裂隙红砂岩压剪断裂判据,明确压剪系数与冻融循环次数、裂隙倾角的关系式。该研究可为探索寒区工程裂隙岩体力学行为以及机制提供一定的防灾减灾理论支持。In response to the effect of freeze-thaw cycles on fractured rocks in the western cold region project,a TDS-300 freeze-thaw testing machine was used to conduct freeze-thaw cycle tests on single fractured red sandstone.The fracture dip angles were selected as 0°,45°,and 90°,and the number of cycles was set to 0,20,40,and 60.A servo universal testing machine was used to conduct uniaxial compression tests on the red sandstone after freeze-thaw damage,and nuclear magnetic resonance(NMR)technology was used to detect the freeze-thaw damage characteristics of the red sandstone.The test results show that as the number of freeze-thaw cycles increases,the elastic modulus,mass,peak strength,and porosity damage variables of red sandstone show varying degrees of increase.Through NMR technology,it is found that the spectral area increases with the number of freeze-thaw cycles,while the development of small pores is slow,and the development of mesopores is rapid in the early stage compared to the later stage,while the number of large pores increases the most.In addition,as the number of freeze-thaw cycles increases,the white spots in the NMR image diffuse from the edge to the center increase,and the damage area gradually enlarges,deepening inward.Based on fracture mechanics,a compression shear fracture criterion for single fractured red sandstone was established under coupling effect of freeze-thaw and load,and the relationship between the compression shear coefficient and the number of freeze-thaw cycles was clarified,as well as the relationship between the compression shear coefficient and the fracture dip angles.This study can provide a theoretical support of disaster prevention and reduction for exploring the mechanical behavior and mechanism of fractured rock masses in cold regions.

关 键 词：冻融损伤 冻融循环 单裂隙红砂岩 NMR 压剪断裂 

分 类 号：TD854[矿业工程—金属矿开采]