摘要
直接拉伸试验是测量岩石抗拉强度最直接有效且最有理论和实际价值的方法,但在传统直接拉伸试验中试样加工难度大,测试设备要求高。为克服传统直接拉伸试验加载困难的缺点,准确测定岩石的抗拉强度,设计研发了多直径岩芯双圆环直接拉伸试验机,从试验和数值模拟两方面重点研究了双圆环直接拉伸试验中试样尺寸的影响和最优取值范围,包括外环直径与试样直径比r_1/R、内环直径与试样直径比r_2/R、内环直径与外环直径比r_2/r_1三个比值的最优范围。研究结果发现,外环直径和内环直径满足r_1/R=0.62±0.08、r_2/R=0.45±0.12、r_2/r_1=0.64±0.06时内外环根部与内外环重叠部位最大应力值相近,获得的抗拉强度与理论值较一致,与其他试验相比,双圆环直接拉伸试验的结果标准差和振荡系数最小。
Theoretically, direct tensile test is the most simple and effective method for determining the tensile strength of rocks, which is both theoretically and practically meaningful. However, clamping the specimens is a major difficult problem, which leads to the difficulties in preparing the specimens and the complicated test equipment. Double concentric annular core tension test is an innovative approach to laboratory determination of tensile strength of rocks, which could overcome the above-mentioned loading disadvantages of the conventional direct tension tests. Firstly, the mechanics of the double concentric annular core tension test is discussed; and then the specimen size effect and optimal size range are investigated experimentally and numerically to obtain more reliable tensile strengths. The results show that the maximum stress near the inner and outer bottom are close to each other and reliable tensile strength could be obtained when the ratio of outer ring diameter to specimen diameter r1/R is 0.62±0.08; the ratio of inner ring diameter to specimen diameter r2/R is 0.45±0.12; and the ratio of inner ring diameter to outer ring diameter r2/r1 is 0.64±0.06. Tensile strength results obtained from these tests could achieve the optimum least standard error and coefficient of variation compared with Brazilian test and hollow cylinder test.
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2018年第S1期191-202,共12页
Rock and Soil Mechanics
基金
国家自然科学基金项目(No.41704096)
中央级科研院所基本科研业务项目(No.ZDJ2017-13)
中国大陆综合地球物理场观测仪器研发专项(No.Y201616)~~
关键词
抗拉强度
双圆环直接拉伸
尺寸效应
最优尺寸范围
tensile strength
double concentric annular core direct tensile test
size effect
optimal size range
