利用瞬态剖面法测定宽级配砾石土水力参数试验研究

Laboratory Investigation of Hydraulic Parameter of Wide-Grading Gravelly Soil by Using Instantaneous Profile Method

土—水特征曲线和渗透函数是土体渗流分析和稳定性研究的重要参数。基于瞬态剖面法原理,加工制作30 cm×30 cm×30 cm(长×宽×高)正方体和30 cm×60 cm(直径×高)的渗透柱,针对宽级配砾石土进行时域反射法标定试验和渗透柱试验。此渗透柱装置可以同时测定不同断面基质吸力和体积含水率变化,试验经进水饱和与排水蒸发阶段,得到宽级配砾石土体积含水率与基质吸力的关系,并根据瞬态剖面法得到非饱和渗透系数随基质吸力的变化关系;同时,采用van Genuchten和Brooks-Corey土—水特征曲线模型和渗透系数函数对其进行分析。结果表明:该渗透柱适用于宽级配砾石土水力参数测定;van Genuchten和Brooks-Corey土—水特征曲线模型都能很好地描述宽级配砾石土土—水特征曲线;Brooks-Corey渗透系数函数在描述宽级配砾石土渗透系数与基质吸力关系要优于van Genuchten渗透系数函数。这种试验方法为宽级配砾石土水力参数的测定提供了参考。

The soil-water characteristic curve and permeability function are important parameters for soil seepage and stability analysis.In order to investigate the hydraulic parameters of wide-grading gravelly soil,a 30 cm×30 cm×30 cm(length×width×height)cube and 30 cm×60 cm(diameter×height)infiltration column was fabricated for the calibration test and infiltration column test of wide-grading gravelly soil.The infiltration column apparatus allows the measurement of both volumetric water content and matric suction at various levels.The infiltration column test was divided into three stages:saturation,drainage,and evaporation.And consequently,the relationship between volumetric water content and matric suction of wide-grading gravelly soil was obtained.Meanwhile,the instantaneous profile method was generally applied to determine the relationship between unsaturated permeability and matric suction.Moreover,the van Genuchten and Brooks-Corey equations and permeability functions were used to fit the test results.The infiltration column apparatus had been proved to be suitable for the determination of soil-water characteristics curves of wide-grading gravelly soil.The van Genuchten and Brooks-Corey model can accurately describe the soil-water characteristics curves.The Brooks-Corey permeability coefficient function was superior to the van Genuchten permeability coefficient function in terms of describing the relationship between the permeability coefficient and matric suction of wide-grading gravelly soil.This research will provide the method for measuring hydraulic parameters of wide-grading gravelly soil.