不同应变率下岩石抗拉与抗压尺寸效应对比研究

发布时间：2018-01-10 02:05

本文关键词：不同应变率下岩石抗拉与抗压尺寸效应对比研究　出处：《南京大学》2015年硕士论文　论文类型：学位论文

【摘要】：作为岩石的两个重要参数,其抗压与抗拉强度一直是岩石力学与工程的研究重点。目前,岩石强度主要通过室内试验获得,而室内试验试样的尺寸远小于实际工程中的岩石尺寸,因此应考虑此类尺寸差异对其强度的影响。同时,岩石强度又受应变率的影响,在动静荷载作用下,岩石强度表现出较大的差异。因此,开展不同应变率(或加载率)条件下的岩石抗拉和抗压强度尺寸效应研究具有重要的理论和实践意义。本文选择了 2种岩石(四川自贡砂岩和甘肃北山花岗岩),对不同尺寸的岩样进行了静态、准静态和动态条件下的单轴压缩和巴西劈裂试验,取得了如下主要成果:1、在静态和准静态条件下,砂岩单轴抗压强度随着尺寸的增加而减小,且应变率越高,尺寸效应越明显;但在动态条件下,其单轴抗压强度却随着尺寸的增加而增加,同时尺寸效应也随着应变率的提高而越发显著。2、砂岩单轴抗压强度随着应变率的增加而增加。在静态和准静态条件下,其关系呈线性增长,同时试样尺寸越小,强度随应变率增加的趋势越明显;而在动态条件下,强度随应变率变化呈幂函数关系,同时试样尺寸越大,应变率效应越显著。3、不同加载率(静态、准静态和动态)条件下,砂岩和花岗岩巴西劈裂抗拉强度均随尺寸的增加而减小,且加载率越高,尺寸效应越明显。4、砂岩和花岗岩巴西劈裂抗拉强度均随加载率的增加而增加。在静态和准静态条件下,巴西劈裂抗拉强度与加载率的对数呈线性关系;而在动态条件下,其强度与加载率呈幂函数关系;同时不同加载率(静态、准静态和动态)条件下,试样尺寸越小,强度随加载率增加的趋势越明显。5、同一加载条件下,砂岩的抗拉与抗压强度比值随着尺寸的减小而增大。在静态和准静态条件下,同一尺寸岩样的拉压比随加载率的增加变化不明显;但在动态条件下,其拉压比却随应变率的增加而变大。
[Abstract]:As the two important parameters of rocks, the compressive strength and tensile strength has been the research focus of rock mechanics and engineering. At present, the rock strength obtained by indoor experiment and indoor test sample size is far less than the actual engineering rock size, therefore should consider the effects of such size differences on its strength. At the same time, the effect of rock the strength and strain rate, the dynamic and static loads, rock strength has shown significant differences. Therefore, to carry out different strain rate (or loading rate) has important theoretical and practical significance to study the size effect of rock tensile strength and compressive strength under the condition of out. This paper selected 2 kinds of rocks (Sichuan Zigong sandstone and Gansu Beishan granite) of different sizes, the samples are static, uniaxial compression and splitting test of Brazil quasi static and dynamic conditions, the main results are as follows: 1, in the static and quasi-static Under the condition of uniaxial compressive strength of sandstone decreases with the increase of the size and strain rate is high, the size effect is more obvious; but under dynamic conditions, the uniaxial compressive strength increases with the increase in size and size at the same time, with the increasing of the strain rate effect also becomes more and more significant.2, the uniaxial compressive strength of sandstone increases with the increase of strain rate. In the static and quasi-static conditions, the relationship between linear growth, and the sample size is small, the strength increases with the increase of strain rate trend is more obvious; while in the dynamic condition, strength with strain rate change was a function of power, while the sample size is large, the effect of strain rate significant.3, different loading rate (static, quasi-static and dynamic conditions), sandstone and granite in Brazil, splitting tensile strength decreased with the increase of the size and the loading rate is high, the more obvious the effect of size.4, splitting tensile sandstone and granite in Brazil Increase strength with loading rate increased. The static and quasi-static conditions in Brazil, there is a linear relationship between splitting tensile strength and the logarithm of loading rate; and under dynamic conditions, the strength and the loading rate is a power function relationship; at the same time, different loading rate (static, quasi-static and dynamic conditions, the sample) the small size and strength with the loading rate increasing trend was more obvious in.5, the same loading condition, the tensile strength and compressive strength ratio of sandstone increases with size decreasing. In the static and quasi-static conditions under tension and compression ratio have no obvious change with the increase of loading rate of the same sample size; but in dynamic under the condition of the tension compression ratio increases with the strain rate becomes larger.

【学位授予单位】：南京大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU45

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