三种典型岩石单轴抗压强度的尺寸效应试验研究

SIZE EFFECT EXPERIMENT OF UNIAXIAL COMPRESSIVE STRENGTH OF THREE TYPICAL ROCKS

尺寸效应是岩石力学领域研究的难点与热点。本文利用自主研发的大尺寸刚性试验机,开展了最大样品尺寸为400 mm×400 mm×800 mm大理岩、闪长岩和凝灰岩的单轴抗压强度试验,从等高宽比条件下岩石强度的尺寸效应和不同高宽比条件下岩石强度变化两个方面开展了岩石强度尺寸效应研究,结果表明:相同高宽比条件下,岩石强度随样品尺寸的增大呈对数形式减小,且逐渐趋于定值;不同高宽比情况,岩石长宽为200 mm×200 mm,高度分别为200 mm,400 mm,600 mm和800 mm,岩石单轴抗压强度随高宽比的增加表现出先减小后增大的变化规律,对应的破坏形式表现为复杂劈裂、劈裂和剪切破坏。本文试验结果为丰富岩石尺寸效应研究提供了基础数据,同时对实际工程中岩体强度尺寸效应的修正具有一定参考价值。

In this paper, the uniaxial compressive strength of marble , diorite and tuffsamples with the maximum sample size 400 mm × 400 mm × 800 mm were tested using the self-developed large-scale rigid testing machine. Two cases of size effect of rock uniaxial compression strength were conducted ： one is with the same aspect ratio and the other is different aspect ratio with the same length and width. The results show that, with the increase of samples dimensions, the uniaxial compression strength decrease in logarithmic function form and gradually approach to a certain value in the case that with the same aspect ratio ; In the case that with different aspect ratios , the length and width of the samples are 200 mm × 200 mm , and the heights are 200 mm , 400 mm, 600 mm and 800 mm respectively. The uniaxial compression strength decreased first and then increased as the increase of aspect ratio of samples. And the corresponding failure modes of samples are complex splitting, splitting and shear failure respectively as the increase of aspect ratio. The results of uniaxial compression strength of different dimensions presented in this paper provide the basic data for the size effect research of rock samples. At the same time,the results have some reference value for the correction of size effect in the practical engineering.