红层泥质胶结物干缩裂缝深度与间距预测模型

Prediction model of desiccation shrinkage fracture depth and spacing of argillaceous cement in red bed mudstone

红层泥质胶结物在干燥条件下会因含水率变化产生开裂,裂缝进一步发展贯通最终导致红层泥岩崩解破坏。目前对红层泥岩崩解机制的研究多为定性描述,缺乏定量分析方法。因此,定量研究红层泥质胶结物开裂的产生及扩展对深化红层泥岩崩解理论研究具有重要意义。基于线弹性断裂力学及非饱和土力学,建立了考虑含水率变化的红层泥质胶结物裂缝深度及间距计算公式,并对公式参数敏感性进行了分析。应用CT试验数据对PFC2D数值模型进行了校准,并基于干缩开裂数值试验结果,对裂缝深度及间距计算公式进行了对比验证。结果表明:提出的计算公式能较好地预测红层泥质胶结物的开裂深度及间距,裂缝深度随含水率减小呈先快速增加再缓慢增长的特点。研究成果有助于加深对红层泥岩崩解的量化理论分析,并为预测工程中红层泥岩的开裂程度提供参考。

Under desiccation conditions,the argillaceous cement of red bed mudstone will crack due to the change of water content,and the cracks will develop further and finally lead to the disintegration of red mudstone.At present,the research on the disintegration mechanism of red mudstone is mostly qualitative description,lack of quantitative analysis method.Therefore,the quantitative study of the occurrence and propagation of the red mudstone argillaceous cement cracking is of great significance to the further theoretical study of the red mudstone disintegration.Based on linear elastic fracture mechanics and unsaturated soil mechanics,a formula that considering water content change was developed to calculate crack depth and spacing of argillaceous cement in red mudstone,and the sensitivity of the formula parameters was analyzed.CT test data were used to calibrate the PFC2D numerical model,and based on the numerical test results of desiccation cracking,the formulas of fracture depth and spacing were compared and verified.The proposed formula can well predict the crack depth and spacing of the red layer argillaceous cement,and the crack depth increases rapidly at first and then slowly with the decrease of water content.The research results are helpful to deepen the quantitative theoretical analysis of red mudstone disintegration and provide reference for predicting the degree of red mudstone cracking in engineering.