卸荷速率和孔隙水压对隧道围岩力学特性影响的试验研究
Experimental study on the influence of unloading rate and pore water pressure on the mechanical characteristics of tunnel surrounding rock
于子洋1
作者信息
- 1. 中铁十九局集团第三工程有限公司,辽宁 沈阳 110136
- 折叠
摘要
针对开挖卸荷和孔隙水压影响隧道围岩稳定性问题,文章结合陕西某在建隧道的工程实际,利用MTS815.02多功能岩石力学试验系统,对该隧道围岩(红砂岩)进行不同卸荷速率和孔隙水压下的三轴卸荷试验,分析不同试验条件下红砂岩各力学参数的变化规律.结果表明:加荷阶段,随着孔隙水压的逐渐增大,弹性模量逐渐减小,卸荷阶段,径向变形增幅显著大于轴向,且孔隙水压越大,差别越大,随着卸荷速率的逐渐增大,峰后曲线跌落逐渐显现,脆性破坏特征逐渐加强;随着孔隙水压的逐渐增大,轴向、径向应变围压柔量均呈逐渐递增趋势;随着卸荷速率的增大,轴向、径向应变围压柔量均呈逐渐递减趋势;同一卸荷速率下,破坏时的围压卸荷量随孔隙水压逐渐减小,孔隙水压越大,破坏时的围压变化量越小,同一孔隙水压下,破坏时的围压卸荷量随卸荷速率逐渐增大,破坏强度略有提升;不同卸荷速率下,孔隙度随孔隙水压呈逐渐递增趋势,二者之间近似满足指数函数关系,拟合相关度均超过 0.95.研究成果可为工程实际提供可靠的理论依据.
Abstract
In addressing the influence of excavation unloading and pore water pressure on the tunnel surrounding rock stability,this paper,in conjunction with the practical engineering scenario of a tunnel under construction in Shaanxi province,conducted triaxial unloading tests using the MTS815.02 test system on the tunnel surrounding rock(red sandstone)under varying unloading rates and pore water pressure.The study aimed to analyze the changes of mechanical parameters of red sandstone under different test conditions.The results revealed that:during the loading stage,the elastic modulus gradually decreases with the increasing pore water pressure.In the unloading stage,the radial deformation increase is significantly greater than that in the axial direction,with the disparity increasing alongside higher pore water pressure.Moreover,With the gradual increase of unloading rate,the post-peak curve drop becomes more pronounced,and the brittle failure characteristics gradually intensify.Additionally,with the rising pore water pressure,the axial and radial strain confining pressure compliance increases gradually,while it decreases with the increase of unloading rate.Furthermore,the confining pressure unloading quantity decreases gradually with the pore water pressure under the same unloading rate,and it increases gradually with the unloading rate under the same pore water pressure,with slightly increasing failure strength.Notably,the porosity increases gradually with pore water pressure under different unloading rates,and the relationship between the two closely approximates an exponential function,with a fitting correlation exceeding 0.95.The research results can provide reliable theoretical basis for engineering practice.
关键词
隧道工程/三轴卸荷/孔隙水压/卸荷速率/应变围压柔量Key words
tunnel engineering/triaxial unloading/pore water pressure/unloading rate/strain confining pressure compliance引用本文复制引用
出版年
2024
NETL
NSTL
维普
万方数据