受拉加载速度变化对砂岩Kaiser效应影响  

Effect of loading rate on Kaiser effect of sandstone under tensile stress

作　　者：傅翔 黄平 班宇鑫 谢强[2] 曾晶 涂义亮 FU Xiang;HUANG Ping;BAN Yuxin;XIE Qiang;ZENG Jing;TU Yiliang(National Engineering Research Center for Inland Waterway Regulation,Chongqing Jiaotong University,Chongqing 400074,P.R.China;School of Civil Engineering,Chongqing University,Chongqing 400044,P.R.China)

机构地区：[1]重庆交通大学国家内河航道整治工程技术研究中心,重庆400074 [2]重庆大学土木工程学院,重庆400045

出　　处：《重庆大学学报（自然科学版）》2019年第5期46-55,共10页Journal of Chongqing University

基　　金：国家自然科学基金项目(51008319,5177902,51808083);国家内河航道整治工程技术研究中心开放基金(SLK2018B04);重庆市教委科学技术研究项目(KJQN201802501,KJQN201800745)~~

摘　　要：为分析受拉加载速度变化下的岩石破坏过程Kaiser效应特征,获取其机理和判断标准,通过3种加载速度的三点弯曲声发射试验,研究了受拉应力状态下砂岩Kaiser点的应力值与加载速度、声发射特征参数间的相互联系。运用RFPA2D从微裂纹开展角度,对试验过程中Kaiser效应随加载速度变化呈现的差异进行了机理分析。最后,运用小波分析方法获取了不同加载速度的砂岩Kaiser点频谱分布区间,量化了其宏观现象的判断标准。结果表明:砂岩的Kaiser效应特征参数与加载速度正相关,各参数的Kaiser点明显程度存在差异,累计事件参数最明显。加载速度越快,岩石裂纹扩展路径的规律性越弱。因裂纹竞争起裂趋势难度的变化,造成开裂能量分布均匀性降低,影响Kaiser效应的准确度和明显程度。Kaiser点的频率主要集中在0~312.50kHz范围,占比为40.54%,最大值在300kHz附近,呈现正态分布,并且Kaiser点的频率区间随加载速度的变化呈现不断紧缩趋势,这一规律可以作为反演辨识岩石受荷冲击强度变化的依据。The paper aims at recognizing the Kaiser effect characteristics of rock tensile failure process with the change of loading rate and acquiring the mechanism and criteria.Firstly,the relationship between Kaiser point stress,loading rate,acoustic emission(AE)parameters were studied.Then,the RFPA2D software was used to simulate the test process from the perspective of micro-crack development.The mechanism of the difference between the Kaiser effect induced by the change of loading rate during the test was analysed.Finally,the spectral characteristics of the Kaiser point under tensile stress was obtained by wavelet analysis and the judging criteria for macroscopic phenomena was quantified.The results show that the KE characteristic parameters of sandstone positively correlated with loading rate.There are great differences in Kaiser point of each parameter,especially in that of the cumulative energy.The faster the loading speed,the weaker the regularity of the rock crack propagation path.Changes of the trend of the crack competition results in the uniformity of the cracking energy distribution,which affect the obviousness and identification accuracy of the Kaiser effect.The frequency of the Kaiser point is mainly concentrated within the range of 0 kHz to 312.50 kHz with normal distribution,accounting for 41.73%,and the maximum value distributes around 300 kHz.The frequency range of Kaiser point shows a constant tightening trend with the change of loading rate,which can be used as the basis for reasonable selection of experimental loading rate for different rocks.The results can provide reference for the stability monitoring,early warning and forecasting work of rock mass roof or compartment rock under bending stress.

关 键 词：KAISER效应 加载速度 三点弯曲 受拉破坏 频谱特征 

分 类 号：TE371[石油与天然气工程—油气田开发工程]