| 摘要: |
| 泥岩强度和变形参数是工程设计与施工控制的重要指标。为研究卸荷作用和水岩作用对膨胀性泥岩强度和变形特性的影响程度，选取南宁盆地典型膨胀性泥岩为研究对象，进行了加卸荷剪切试验和无荷膨胀率试验，在此基础上，分析了卸荷泥岩强度变化规律，探讨了水岩作用对卸荷泥岩变形特性的影响程度。试验结果表明，卸荷作用引起泥岩强度降低，压缩性增大，相比于加载条件，卸荷状态下泥岩的黏聚力明显较高，而内摩擦角则相对较小。引入卸荷比和强度损失率分析了卸荷泥岩的强度变化规律，卸荷泥岩强度损失率随卸荷比增加而增大，当卸荷比为0.7～0.8时，泥岩强度损失率最大。相对于卸荷作用，水岩作用对泥岩变形特性的影响较大，对样品的损伤约占30%～65%。研究结果表明获取试样力学参数中不能忽略取样过程对泥岩强度和变形特性的影响。 |
| 关键词: 泥岩 取样卸荷 应力路径 强度 变形 |
| DOI： |
| 分类号:TU43 |
| 基金项目:广西自然科学基金资助项目（2011GXNSFB018002）； 广西高校中青年教师基础能力提升项目（KY2016YB586） |
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| Experimental study of unloading impact on deformation behavior and strength of mudstone in sampling state |
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MA Furong, ZHANG Xingui, YI Nianping
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College of Civil Engineering and Architecture, Guangxi University, Nanning
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| Abstract: |
| The strength and deformation characteristics of mudstone are important reference indexes in the engineering design and construction management. In order to analyse the effect of water rock interaction and unloading on the strength properties and deformation characteristics of expansive mudstone, the sample of typical expansive mudstone in Nanning basin is chosen for the loading and unloading shear test and unloaded expansion ratio test. The intensity change rule of unloading mudstone is analyzed. And the influence of water rock interaction on the deformation characteristics is discussed. The deformation and the curve of unloaded expansion ratio test are obtained. The experimental results show that sampling unloading has a great influence on the strength and compressibility, as well as the expansion deformation. Due to the unloading, the strength of mudstone decreases and the compression ratio of mudstone increases. The internal friction angle under unloading condition is smaller than that under the loading condition, while the value of cohesion increases. The unloading ratio and the loss strength rate are used to analyze the variation law of the strength of unloading mudstone. With the increase of the unloading ratio, the loss strength rate of unloading mudstone also increases. When the unloading ratio is between 0.7 and 0.8, the loss rate of mudstone strength is the largest. Compared with the unloading effect, the water rock interaction has a greater influence on the deformation characteristics of unloading mudstone, and its structural damage to mudstone is up to 30% ~ 65% during the sampling progress. So, the influence of sampling process on the strength and deformation characteristics of mudstone cant be ignored. |
| Key words: mudstone sampling unloading stress path strength deformation |
