饱和含细砾砂动孔隙水压力特性三轴试验研究

Triaxial Tests Study on Dynamic Pore Water Pressure Characteristics of Saturated Fine Gravel Sand

利用TAJ—20振动三轴仪对饱和含细砾砂进行振动三轴试验,研究了几种不同因素下砾砂的孔压发展规律;并采用双曲线孔压模型进行了拟合。试验结果表明:随着振动周次和动应力幅值的增加,动孔隙水压力逐渐增加,而动孔压随固结应力比的增大逐渐减小。等压固结含细砾砂孔压均能达到围压,而偏压固结孔压是否达到围压主要取决于动应力幅值能否大于主应力差,即动应力是否足够大;但当固结应力比太大,孔隙水压力不能达到围压。饱和含细砾砂动孔压比增长随相对密度的增大而减缓,当达到相同的动孔压比,相对密度越大,振动破坏所需的振动周次也就越多,土体就越不容易破坏。振动频率越快,动孔压比上升越快,即孔隙水压力上升速度越快。当达到相同的孔隙水压力时,振动频率越快,振动破坏所需的时间就越少。饱和含细砾砂动孔压发展可用双曲线模型很好的拟合,可为工程实践和试验资料的积累提供依据。

The triaxial tests of saturated fine gravel sand was carried out by using the TAJ—20 vibration triaxial apparatus.The development law of pore water pressure under several different factors was studied,and the hyperbolic model of pore pressure was used for fitting.Experimental results show that： with the vibration frequency and dynamic stress amplitude increases,dynamic pore water pressure gradually increases,with increasing consolidation stress ratio moving hole pressure decreases.Isotropical consolidation of saturated fine gravel sand pore water pressure can reach confining pressure,however pore water pressure can reach anisotropical consolidation confining pressure depends primarily on whether the dynamic stress amplitude is greater than the principal stress difference,unless the dynamic stress is large enough.However,when the consolidation stress ratio is too large,the pore water pressure can not reach confining pressure.Dynamic pore water pressure ratio of saturated fine gravel sand with increasing relative density slows,when to achieve the same dynamic pore water pressure ratio,the greater relative density is,the more the required vibration vibration damage times are,The more difficult to fail for soil.The faster the vibration frequency is,dynamic pore water pressure rises sooner,that is to say： pore water pressure rise faster.When the same pore water pressure is reached,the vibration frequency is higher,and the time required for vibration failure is less.The development of saturated fine gravel sand can be used to fit hyperbola model well,which can provide the basis for engineering practice and experimental data.