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尺寸效应的研究在评估节理/裂隙岩体力学性质方面具有重要意义,通过离散元数值方法研究尺寸效应。引入Voronoi图模拟随机节理,以相对标准差为标准,衡量试验结果的稳定性和可靠度,进行了足够次数不同尺寸的单轴压缩数值试验。进而采用统计方法分析Eeq(等效弹性模量)和1/Eeq(等效柔量)的尺寸效应。研究表明:相对标准差值为5%对应的变形REV(representative elementary volume)尺寸约为4倍Voronoi多边形平均边长;样本Eeq的均值随着尺寸的增大显著降低,而样本1/Eeq的均值随尺寸变化很小。对结论的适用性进行了分析,实际工程中多采用样本Eeq的均值估算岩体的整体等效弹性模量,建议同时采用1/Eeq均值的倒数估算其下限。并将此方法应用于白鹤滩水电站节理岩体原位变形试验成果的分析。
The study of size effect is of great significance in evaluating the mechanical properties of joint / fractured rock mass. The size effect is studied by discrete element numerical method. Voronoi diagram is introduced to simulate stochastic joints. The relative standard deviation (RSD) is used as a standard to measure the stability and reliability of the test results. Numerical tests of uniaxial compression of different sizes are carried out for a sufficient number of times. A statistical method is then used to analyze the size effect of Eeq and 1 / Eeq. The results show that the representative elementary volume of REV corresponding to 5% relative standard deviation is about 4 times the average length of Voronoi polygon. The mean value of sample Eeq decreases with the increase of size, while the mean of sample 1 / Eeq Small changes with the size. The applicability of the conclusion is analyzed. In practice, the Eeq average of the samples is used to estimate the overall equivalent elastic modulus of the rock mass. It is suggested that the lower limit should be estimated by using the reciprocal of 1 / Eeq mean. And this method is applied to the analysis of the in situ deformation test results of jointed rock mass of Baihetan Hydropower Station.