作者：李鹏飞1,2, 赵星光2,3, 马利科2,3, 黄正均4
作者单位：1. 中国核工业集团有限公司, 北京 100822;
2. 国家原子能机构高放废物地质处置创新中心, 北京 100029;
3. 核工业北京地质研究院, 北京 100029;
4. 北京科技大学土木与资源工程学院, 北京 100083
关键词：高放废物;北山花岗岩;室内试验;端部效应;减摩剂
摘要：
从我国高放废物地质处置工程室内试验技术需求出发，以北山花岗岩为研究对象，开展岩石在单轴压缩条件下的端部效应试验研究。通过开展4种高径比、3种端面条件下的岩石单轴压缩试验，获取岩石应力-应变曲线，得出岩石关键力学参数与高径比和端面条件之间的关系，进一步探讨端部效应带来的影响以及弱化/去除端部效应的方法。研究结果表明：1）端部效应对岩石力学参数测量结果的影响程度受岩样高径比和加载端面条件的共同作用，在岩石应力水平较高且变形趋势较大时，端部效应才真正发挥作用；2）在端面为普通垫板的加载条件下，端部效应随着岩样高径比的降低而增强，当岩石高径比由2.3下降到1.2时，岩石峰值应力测量结果均值提高约45.14 MPa，增长率约36%；3）采用减摩剂、自制减摩剂+铜箔片2种方式处理加载端面可有效减小端部效应，岩石峰值应力测量结果不再依赖岩样高径比的变化；4）端部效应对岩石弹性模量、泊松比、启裂应力、贯通应力等其他关键力学参数测量结果的影响不大。该文研究成果可为深入分析端部效应产生机理及优化复杂岩石力学试验设计提供有益参考。
Experimental study on end effect of Beishan granite under uniaxial compression
LI Pengfei1,2, ZHAO Xingguang2,3, MA Like2,3, HUANG Zhengjun4
1. China National Nuclear Corporation, Beijing 100822, China;
2. CAEA Innovation Center for Geological Disposal of High-Level Radioactive Waste, Beijing 100029, China;
3. Beijing Research Institute of Uranium Geology, Beijing 100029, China;
4. School of Civil and Resource Engineering, University of Science and Technology Beijing, Beijing 100083, China
Abstract: Based on technical requirements of laboratory testing for geological disposal of high-level radioactive waste in China, uniaxial compression tests on Beishan granite samples under different conditions were carried out for investigating the influence of end effect on experimental results. By conducting uniaxial compression tests on rock samples with 4 kinds of height-diameter ratios and 3 kinds of end-face conditions, the stress-strain curves of rock samples were measured. The relationships between key mechanical parameters of the rock and height-diameter ratio and end-face condition were obtained. Influence of end effects on measurement results, and methods to reduce or remove end effects in laboratory rock mechanics tests were discussed. The results show that:1) The influence of the end effect on the measurement results of rock mechanical parameters is dominated by the height-diameter ratio of the rock sample and the loading end-face condition. The end effect starts to appear when the applied stress level is high, and rock deformation is large. 2) Under the loading condition where the end faces are loaded by normal platens, the end effect increases with the decrease of height-diameter ratio of rock samples. When the height-diameter ratio of rock samples decreases from 2.3 to 1.2, the average peak stress of rock samples increases by about 45.14 MPa, and the increase ratio is about 36%. 3) The end effect can be effectively reduced when the end faces of rock samples are treated by using self-made friction reducer, and friction reducer coupled with copper foil. The peak stress measurement results of rock samples no longer depend on the variation of the sample height-diameter ratio. 4) The end effect has little effect on other mechanical parameters such as Young's modulus, Poisson's ratio, crack initiation stress, and damage stress. The research results can provide a meaningful reference for further analysis of the end effect generation mechanism and optimization of complicated rock mechanics test design.
Keywords: high-level radioactive waste;Beishan granite;laboratory test;end effect;friction reducer
2023, 49(5):181-188 收稿日期: 2022-08-03;收到修改稿日期: 2022-09-25
基金项目:
作者简介: 李鹏飞(1991-),男,江苏徐州市人,工程师,硕士,主要从事高放废物处置相关的岩石力学研究工作
参考文献
[1] 王驹, 陈伟明, 苏锐, 等. 高放废物地质处置及其若干关键科学问题[J]. 岩石力学与工程学报, 2006(4): 801-812
[2] 陈亮, 刘建锋, 王春萍, 等. 不同温度及应力状态下北山花岗岩蠕变特征研究[J]. 岩石力学与工程学报, 2015, 34(6): 1228-1235
[3] 李鹏飞, 赵星光, 郭政, 等. 北山花岗岩在三轴压缩条件下的强度参数演化[J]. 岩石力学与工程学报, 2017, 36(7): 1599-1610
[4] HUDSON J A, CROUCH S L, FAIRHURST C. Soft, stiff and servo-controlled testing machines: a review with reference to rock failure[J]. Engineering Geology, 1972, 6(3): 155-189
[5] BAZANT Z P, XIANG Y. Size effect in compression fracture: splitting crack band propagation[J]. Journal of Engineering Mechanics, 1997, 123(2): 207-213
[6] KAMPMANN R, RODDENBERRY M, PING W V. Contribution of specimen surface friction to size effect and rupture behavior of concrete[J]. Aci Materials Journal, 2013, 110(2): 169-176
[7] 尤明庆. 常规三轴压缩的端部效应及花岗岩强度的研究[J]. 岩石力学与工程学报, 2018, 37(S1): 3160-3168
[8] 梁正召, 吴宪锴, 唐世斌, 等. 基于各向异性界面单元的岩石端部效应数值模拟[J]. 应用基础与工程科学学报, 2018, 26(3): 526-537
[9] ZHAO X G, WANG J, CAI M, et al. Influence of intermediate principal stress on the strainburst characteristics of Beishan granite with consideration of end effect[J]. Rock Mechanics and Rock Engineering, 2021, 54: 4771-4791
[10] 苏荣华, 马志远, 薛佳琪. 端部效应对砂岩单轴压缩蠕变特性影响[J]. 辽宁工程技术大学学报, 2022, 41(1): 27-34
[11] 贾敬锎, 黄滚, 汪龙, 等. 单轴压缩试验中减弱端部效应新型方法研究[J]. 黄金科学技术, 2021, 29(3): 382-391
[12] 彭俊, 蔡明, 荣冠, 等. 裂纹闭合应力及其岩石微裂纹损伤评价[J]. 岩石力学与工程学报, 2015, 34(6): 1091-1100
[13] NICKSIAR M, MARTIN C D. Evaluation of methods for determining crack initiation in compression tests on low-porosity rocks[J]. Rock Mechanics and Rock Engineering, 2012, 45(4): 607-617
[14] 李鹏飞, 赵星光, 蔡美峰. 压缩条件下岩石启裂应力的识别方法探讨—以新疆天湖花岗闪长岩为例[J]. 岩土力学, 2015, 36(8): 2323-2331
