周期性的蒸发和降雨作用导致膨胀土裂隙发育,而裂隙对土体的水力及强度特性有很大影响。为研究膨胀土在干湿循环作用下的裂隙发展规律及其土水特征,采用CT扫描技术和图像处理程序定量分析裂隙的发育演化过程;利用压力板仪进行合肥膨胀...周期性的蒸发和降雨作用导致膨胀土裂隙发育,而裂隙对土体的水力及强度特性有很大影响。为研究膨胀土在干湿循环作用下的裂隙发展规律及其土水特征,采用CT扫描技术和图像处理程序定量分析裂隙的发育演化过程;利用压力板仪进行合肥膨胀土土水特征曲线的干湿循环效应试验。研究结果表明:基于CT图像可以得到试样内部裂隙的二维、三维结构及其定量化分析指标;各个裂隙指标的裂隙发育过程可以用logistic函数的生长曲线描述。裂隙对膨胀土的土水特征曲线影响较大,裂隙膨胀土的土水特征曲线呈"双峰"形态;随干湿循环次数增加,膨胀土持水能力降低,不同循环次数的土水特征曲线差异性明显,吸力200~450 k Pa阶段,不同循环次数下膨胀土土水特征曲线逐渐趋于一致;干湿循环对SWCC1和SWCC2特征点(进气值,残余值)的影响程度不同;通过灰色关联法分析发现,平均裂隙宽度、内表面积、平均裂隙长度、体积裂隙度和面积裂隙度均与裂隙膨胀土的持水能力有显著的相关联性;以干湿循环次数和基质吸力为变量建立双峰土水特征曲线模型,采用合肥膨胀土的土水特征曲线试验数据验证了模型的精确性及可靠性,饱和含水率、拟合参数都与干湿循环次数呈良好的相关性。展开更多
Rock residual strength,as an important input parameter,plays an indispensable role in proposing the reasonable and scientific scheme about stope design,underground tunnel excavation and stability evaluation of deep ch...Rock residual strength,as an important input parameter,plays an indispensable role in proposing the reasonable and scientific scheme about stope design,underground tunnel excavation and stability evaluation of deep chambers.Therefore,previous residual strength models of rocks established were reviewed.And corresponding related problems were stated.Subsequently,starting from the effects of bedding and whole life-cycle evolution process,series of triaxial mechanical tests of deep bedded sandstone with five bedding angles were conducted under different confining pressures.Then,six residual strength models considering the effects of bedding and whole life-cycle evolution process were established and evaluated.Finally,a cohesion loss model for determining residual strength of deep bedded sandstone was verified.The results showed that the effects of bedding and whole life-cycle evolution process had both significant influences on the evolution characteristic of residual strength of deep bedded sandstone.Additionally,residual strength parameters:residual cohesion and residual internal friction angle of deep bedded sandstone were not constant,which both significantly changed with increasing bedding angle.Besides,the cohesion loss model was the most suitable for determining and estimating the residual strength of bedded rocks,which could provide more accurate theoretical guidance for the stability control of deep chambers.展开更多
文摘周期性的蒸发和降雨作用导致膨胀土裂隙发育,而裂隙对土体的水力及强度特性有很大影响。为研究膨胀土在干湿循环作用下的裂隙发展规律及其土水特征,采用CT扫描技术和图像处理程序定量分析裂隙的发育演化过程;利用压力板仪进行合肥膨胀土土水特征曲线的干湿循环效应试验。研究结果表明:基于CT图像可以得到试样内部裂隙的二维、三维结构及其定量化分析指标;各个裂隙指标的裂隙发育过程可以用logistic函数的生长曲线描述。裂隙对膨胀土的土水特征曲线影响较大,裂隙膨胀土的土水特征曲线呈"双峰"形态;随干湿循环次数增加,膨胀土持水能力降低,不同循环次数的土水特征曲线差异性明显,吸力200~450 k Pa阶段,不同循环次数下膨胀土土水特征曲线逐渐趋于一致;干湿循环对SWCC1和SWCC2特征点(进气值,残余值)的影响程度不同;通过灰色关联法分析发现,平均裂隙宽度、内表面积、平均裂隙长度、体积裂隙度和面积裂隙度均与裂隙膨胀土的持水能力有显著的相关联性;以干湿循环次数和基质吸力为变量建立双峰土水特征曲线模型,采用合肥膨胀土的土水特征曲线试验数据验证了模型的精确性及可靠性,饱和含水率、拟合参数都与干湿循环次数呈良好的相关性。
基金Projects(2024YFC3013801,2022YFC3004602)supported by the National Key R&D Program of ChinaProjects(U23B2093,52034009)supported by the National Natural Science Foundation of China。
文摘Rock residual strength,as an important input parameter,plays an indispensable role in proposing the reasonable and scientific scheme about stope design,underground tunnel excavation and stability evaluation of deep chambers.Therefore,previous residual strength models of rocks established were reviewed.And corresponding related problems were stated.Subsequently,starting from the effects of bedding and whole life-cycle evolution process,series of triaxial mechanical tests of deep bedded sandstone with five bedding angles were conducted under different confining pressures.Then,six residual strength models considering the effects of bedding and whole life-cycle evolution process were established and evaluated.Finally,a cohesion loss model for determining residual strength of deep bedded sandstone was verified.The results showed that the effects of bedding and whole life-cycle evolution process had both significant influences on the evolution characteristic of residual strength of deep bedded sandstone.Additionally,residual strength parameters:residual cohesion and residual internal friction angle of deep bedded sandstone were not constant,which both significantly changed with increasing bedding angle.Besides,the cohesion loss model was the most suitable for determining and estimating the residual strength of bedded rocks,which could provide more accurate theoretical guidance for the stability control of deep chambers.
