不同风化程度下灰岩抗剪强度特性及估算模型研究

A study of shear strength characteristics and estimation model of limestone under different weathering degrees

工程上常见的灰岩在不同风化程度下的抗剪强度特性鲜有研究,也没有快速评估灰岩抗剪强度的数学模型,不能满足大量灰岩工程灾害防治的需要。为探究风化程度对灰岩抗剪强度特性的影响规律,试验选取现场新鲜灰岩试样,通过开展室内风化模拟试验制备不同风化程度的岩样,进行室内岩石强度剪切试验,探究灰岩剪切应力-剪切位移关系曲线的变化规律和抗剪强度的劣化规律。通过建立风化程度下灰岩抗剪强度估算模型,揭示风化程度与抗剪强度的定量化关系。试验结果表明:随着风化程度的增加,灰岩抗剪强度和残余抗剪强度均呈现减小的趋势,但残余抗剪强度比抗剪强度劣化更严重,且劣化速度更快;灰岩随着风化程度的增加,其黏聚力c及内摩擦角φ均越来越小,两者劣化趋势相似;利用波速比量化风化程度,建立起风化作用下灰岩抗剪强度估算模型,通过简单测量计算岩石的波速比,即可快速评估岩石的抗剪强度特性。研究结果可为灰岩工程抗剪强度特性的评估提供更加简便易行的方法。

The shear strength characteristics of common limestone in engineering under different weathering degrees were seldom examined,and there is no mathematical model for rapid evaluation of the shear strength of limestone,which cannot meet the needs of prevention and control of a large number of limestone engineering disasters.In order to explore the influence of weathering degree on the shear strength characteristics of limestone,the fresh limestone samples are selected in the test.The rock samples with different weathering degrees are prepared by indoor weathering simulation test.The indoor rock strength shear test is carried out to explore the variation law of the shear stress-shear displacement curve of limestone and the deterioration law of shear strength and its parameters.The quantitative relationship between the weathering degree and shear strength is revealed by establishing the shear strength estimation model of limestone under weathering degree.The test results show that with the increasing weathering degree,the shear strength and residual shear strength of limestone show a decreasing trend,but the residual shear strength is worse than the shear strength,and the deterioration rate is faster.With the increasing weathering degree,the cohesion c and internal friction angle φ of limestone are getting smaller and smaller,and the deterioration trend is similar.Using the wave velocity ratio to quantify the weathering degree,the shear strength estimation model of limestone under weathering is established.The shear strength characteristics of rock can be quickly evaluated by simply measuring and calculating the wave velocity ratio of rock.The research results can provide a more simple and feasible method for evaluating the shear strength characteristics of limestone engineering.