浸水次数影响下裂隙砂岩强度损伤及声发射特征

Strength damage and AE characteristics of fractured sandstone under the influence of water intrusion times

循环浸水能够造成工程岩体结构及其力学性质的弱化,对工程岩体的稳定性产生一定影响。为探讨在反复浸水影响下裂隙砂岩强度损伤特征,采用无损浸水试验装置制取浸水0,1,2和3次的标准砂岩岩样和预制裂隙砂岩岩样,研究了其强度损伤及声发射特征。研究结果表明:随着浸水次数增加,砂岩单轴抗压强度和弹性模量减小,而对其破坏形式无显著影响;不同浸水次数影响下的裂隙砂岩全应力-应变曲线均呈现裂隙压密、弹性变形、塑性变形和峰后4个阶段;声发射计数频率和范围随浸水次数增加而减小;标准砂岩起裂位置在试样中部,裂隙砂岩起裂位置在预制裂隙上下端附近;浸水次数越多,声发射定位数量越少,预制裂隙附近损伤越大,在荷载作用下周围产生次生裂隙。研究成果对岩土工程中涉及的反复浸水问题的研究提供了有益参考。

Cyclic intrusion can weaken the structure and mechanical properties of engineering rock mass, which affects the stability of engineering rock mass to some extent. In order to study the strength damage characteristics of fractured sandstone under the influence of repeated intrusion, the standard sandstone samples and prefabricated fractured sandstone samples with respective 0, 1, 2 and 3 times of intrusion have been prepared with the non-destructive intrusion test device, and their strength damage and acoustic emission characteristics have been studied. The results have shown that with the increase of intrusion times, the uniaxial compressive strength and elastic modulus of sandstone decrease, but there is no significant influence on its failure mode. The total stress-strain curves of fractured sandstone under the influence of different times of water intrusion show four stages: fracture compaction stage, elastic deformation stage, plastic deformation stage, and post peak stage. The frequency and range of AE counting decrease with the increase of intrusion times. The crack initiation position in the standard sandstone is in the middle of the sample, while the crack initiation position in the fractured sandstone is near the upper and lower end of the prefabricated crack. The more the times of intrusion, the less the number of acoustic emission location, and the greater the damage near the prefabricated cracks, with the secondary cracks generated around the cracks under the load. The research results provide useful reference for the study of repeated intrusion in geotechnical engineering.