黏土中的孔压测试试验及其传递滞后机理

Experimental Research on Pore Pressure and Transfer Mechanismin Clay

饱和黏土中的孔压传递过程是进行岩土工程问题机理分析的基础,其在传递过程中是否有滞后及所涉影响因素一直备受关注。对此,设计了一套测试装置,对经固结的饱和黏土施加水压进行孔压传递测试,并在此基础上开展数值仿真分析。试验发现饱和黏土中的孔压传递存在明显滞后现象,且固结压力越大,滞后时间越长;建立的数值仿真模型模拟了孔压传递过程,分析发现孔隙水压缩系数和土体渗透系数是孔压传递滞后的主要影响因素。进一步运用数值仿真手段对这2种影响因素进行参数分析,结果表明:孔压传递滞后时长总体随孔隙水压缩系数的增大或土体渗透系数的减小而增长,尤其在孔隙水压缩系数>10^(-5) kPa^(-1)、土体渗透系数<10^(-8) m/s的情况下,滞后时长的变幅剧烈。

The transmission of pore water pressure in saturated clay is the foundation for analyzing geotechnical engineering problems.Delays in the transmission process and factors influencing the delay have attracted wide attentions.A testing apparatus was designed to examine the transfer of pore pressure by applying hydraulic pressure to consolidated saturated clay.Subsequently,a numerical model was established to simulate the transfer process of pore water pressure.The results reveal noticeable hysteresis in the transmission of pore pressure in saturated clay,with the duration of hysteresis increasing in proportion to the consolidation pressure.Pore water compression coefficient and soil permeability coefficient are primary factors affecting the hysteresis of pore water pressure transfer.Additionally,further numerical simulations demonstrate that an increase in pore water compression coefficient or a decrease in soil permeability leads to an extended lag time in pore pressure transfer.Specifically,when the pore water compression coefficient exceeds 10^(-5) kPa^(-1) and the soil permeability coefficient is lower than 10^(-8) m/s,the lag time variations become more pronounced.