地铁隧道基底围岩动三轴试验研究

Dynamic triaxial test for basement surrounding rock of metro tunnel

为研究列车荷载对地铁隧道基底围岩的动力响应机制问题,以地铁某站为工程背景,采用GDS动三轴试验系统对饱和中风化粉砂岩进行研究,分析不同静偏应力比、动应力比、加载频率及围压对饱和中风化粉砂岩作用机制。结果表明:随着加载循环次数的逐渐增大,累计塑性应变曲线在静偏应力比小于等于0.369时表现为稳定型,在静偏应力比为0.5时表现为非稳定型,累计塑性应变与静偏应力比呈指数函数递增关系;累计塑性应变曲线在动应力比小于等于0.048时表现为稳定型,在动应力比为0.07时表现为非稳定型,累计塑性应变与动应力比呈指数函数递增关系;不同加载频率下中风化粉砂岩的累计塑性应变曲线均表现为稳定型,累计塑性应变与加载频率之间呈线性函数递减关系;不同围压下中风化粉砂岩的累计塑性应变曲线均表现为稳定型,累计塑性应变与围压之间呈线性函数递减关系。

To study the dynamic response mechanism of train load to subway tunnel basement surrounding rock mass,taking a subway station as engineering example,using GDS dynamic triaxial test system to study saturated moderate weathering silty sandstone,this paper analyzed effect mechanism of different static deviatoric stress ratio,dynamic stress ratio,loading frequency,and confining pressure on saturated moderate weathering silty sandstone.Results showed that with increasing of loading cycles,the cumulative plastic strain curve was stable type when the ratio of static deviatoric stress was less than or equal to 0.369,and unstable type,with an exponentially increase,when the ratio of static deviatoric stress was 0.5.The accumulative plastic strain curve was stable when the dynamic stress ratio was less than or equal to 0.048,and unstable type,with an exponentially increase,when the dynamic stress ratio was 0.07.The accumulative plastic strain curves of moderately weathering siltstone were stable under different loading frequencies,and the relationship between accumulative plastic strain linearly decreased with increase of loading frequency.The accumulative plastic strain curves of moderately weathering siltstone under different confining pressures were stable.The relationship between accumulated plastic strain and confining pressure was linear decreasing.