Estimation of Confined Peak Strength of Crack-Damaged Rocks
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- 作者：Navid Bahrani ; Peter K. Kaiser
- 关键词：Micro ; crack ; Confined strength ; Strength Degradation Approach (SDA) ; Particle Flow Code (PFC) ; Grain ; based Model (GBM) ; Confidence Interval (CI)
- 刊名：Rock Mechanics and Rock Engineering
- 出版年：2017
- 出版时间：February 2017
- 年：2017
- 卷：50
- 期：2
- 页码：309-326
- 全文大小：
- 刊物类别：Earth and Environmental Science
- 刊物主题：Geophysics/Geodesy; Civil Engineering;
- 出版者：Springer Vienna
- ISSN：1434-453X
- 卷排序：50
文摘
It is known that the unconfined compressive strength of rock decreases with increasing density of geological features such as micro-cracks, fractures, and veins both at the laboratory specimen and rock block scales. This article deals with the confined peak strength of laboratory-scale rock specimens containing grain-scale strength dominating features such as micro-cracks. A grain-based distinct element model, whereby the rock is simulated with grains that are allowed to deform and break, is used to investigate the influence of the density of cracks on the rock strength under unconfined and confined conditions. A grain-based specimen calibrated to the unconfined and confined strengths of intact and heat-treated Wombeyan marble is used to simulate rock specimens with varying crack densities. It is demonstrated how such cracks affect the peak strength, stress–strain curve and failure mode with increasing confinement. The results of numerical simulations in terms of unconfined and confined peak strengths are used to develop semi-empirical relations that relate the difference in strength between the intact and crack-damaged rocks to the confining pressure. It is shown how these relations can be used to estimate the confined peak strength of a rock with micro-cracks when the unconfined and confined strengths of the intact rock and the unconfined strength of the crack-damaged rock are known. This approach for estimating the confined strength of crack-damaged rock specimens, called strength degradation approach, is then verified by application to published laboratory triaxial test data.