动态多步流动法预测非饱和土水力学参数
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摘要
选取4种具有代表性的土样,运用Wei和Muraleetharan提出的饱和度随时间的演化方程对其进行动态多步流动试验,来预测其非饱和土的水力学参数。以平衡态法的试验结果作为参考标准,将预测结果与其相比较发现:在砂土与粉土的试验中,试样饱和度较大时两者偏差较大,这是由于试验采取的3 Bar陶土板的渗透系数与砂土和粉土的渗透系数相差较大,导致孔隙水不能被及时排出。粉质黏土的预测结果与平衡态试验结果非常接近,说明该方法对粉质黏土的预测非常有效。由于受到实验设备与陶土板规格的限制,黏土的预测范围偏小,但是预测结果较为理想。通过平衡态实验发现,4种土样的土水特征曲线均为典型的"S"型曲线,以进气值与残余饱和度为分界点可将其分为三部分。动态多步流动试验根据该三个部分来确定试验的吸力增量与吸力步长,并给出了合理的值。
Four kinds of typical soil samples were used to predict the unsaturated soil hydraulic parameters by the dynamic multistep outflow experiments with the time evolution equation by Wei and Muraleetharan. The results of the equilibrium method were used as the reference standard,and compared with those of the predicted results. It is found that when the sample saturation is great,there are more differences between them in the tests of sandy soil and silty soil. This is because the permeability coefficient of 3 bar clay plate is totally different from that of sandy soil and silty soil,which leads to the fact that pore water can not be discharged in time. The prediction of silty clay soil is very close to the equilibrium test results,which shows that this method is very effective for predicting silty clay soil. Due to the limitation of the specifications of the experimental equipment and the clay plate,the prediction range of clay is small,but the prediction results are satisfactory. It is found that the soil water characteristic curves of the four kinds of soil samples are typical "S" curve by the equilibrium tests,which can be divided into three parts by the air entry value and the residual saturation. According to the three parts,the dynamic multistep outflow experiments can be used to determine the value of suction increment and suction step.
Four kinds of typical soil samples were used to predict the unsaturated soil hydraulic parameters by the dynamic multistep outflow experiments with the time evolution equation by Wei and Muraleetharan. The results of the equilibrium method were used as the reference standard,and compared with those of the predicted results. It is found that when the sample saturation is great,there are more differences between them in the tests of sandy soil and silty soil. This is because the permeability coefficient of 3 bar clay plate is totally different from that of sandy soil and silty soil,which leads to the fact that pore water can not be discharged in time. The prediction of silty clay soil is very close to the equilibrium test results,which shows that this method is very effective for predicting silty clay soil. Due to the limitation of the specifications of the experimental equipment and the clay plate,the prediction range of clay is small,but the prediction results are satisfactory. It is found that the soil water characteristic curves of the four kinds of soil samples are typical "S" curve by the equilibrium tests,which can be divided into three parts by the air entry value and the residual saturation. According to the three parts,the dynamic multistep outflow experiments can be used to determine the value of suction increment and suction step.
引文
[1]Fredlund D G,Xing A Q,Fredlund M D,et al.The relationship of the unsaturated soil shear strength to the soil-water characteristic curve[J].Canadian Geotechnical Journal,1996,33(3):440-448.
[2]Vanapalli S K,Fredlund D G,Pufahl D E.The relationship between the soil-water characteristic curve and the unsaturated shear strength of a compacted glacial till[J].Geotechnical Testing Journal,1996,19(3):259-268.
[3]van Genuchten M T.A closed-form equation for predicting the hydraulic conductivity of unsaturated soils[J].Soil Science Society of America Journal,1980,44(5):892-898.
[4]Mualem Y.A new model for predicting the hydraulic conductivity of unsaturated porous media[J].Water Resources Research,1976,12(3):513-522.
[5]Fredlund D G,Xing A Q,Huang S Y.Predicting the permeability function for unsaturated soils using the soil-water characteristic curve[J].Canadian Geotechnical Journal,1994,31(4):533-546.
[6]傅鑫晖,韦昌富,颜荣涛,等.桂林雁山红黏土的土-水特征试验[J].桂林理工大学学报,2013,33(3):488-492.
[7]常红帅,刘丽,季春生,等.桂林、柳州两种红黏土的土-水特征曲线[J].桂林理工大学学报,2015,35(4):855-859.
[8]张爱伟,张家文,于明波,等.南宁地区非饱和残积黏土持水性试验[J].桂林理工大学学报,2018,38(1):112-116.
[9]Gardner W R.Calculation of capillary conductivity from pressure plate outflow data[J].Soil Science Society of America Journal,1956,20(3):317-320.
[10]Doering E J.Soil-water diffusivity by the one-step method[J].Soil Science,1965,99(5):322-326.
[11]van Dam J C,Stricker J N M,Droogers P.Inverse method for determining soil hydraulic functions from one-step outflow experiments[J].Soil Science Society of America Journal,1992,56(4):1042-1050.
[12]Eching S O,Hopmans J W.Optimization of hydraulic functions from transient outflow and soil water pressure data[J].Soil Science Society of America Journal,1993,57(5):1167-1175.
[13]Eching S O,Hopmans J W,Wendroth O.Unsaturated hydraulic conductivity from transient multistep outflow and soil water pressure data[J].Soil Science Society of America Journal,1994,58(3):687-695.
[14]Lu N,Wayllace A,Carrera J,et al.Constant flow method for concurrently measuring soil-water characteristic curve and hydraulic conductivity function[J].Geotechnical Testing Journal,2006,29(3):230-241.
[15]Hassanizadeh S M,Gray W G.Mechanics and thermodynamics of multiphase flow in porous media including interphase boundaries[J].Advances in Water Resources,1990,13(4):169-186.
[16]Wei C,Dewoolkar M M.A continuum theory of nonequilibrium two-phase flow through porous media with capillary relaxation[M]//Advances in Unsaturated Soil,Seepage,and Enviromental Geotechnics,2006:246-254.
[17]Wei C F,Muraleetharan K K.Linear viscoelastic behavior of porous media with non-uniform saturation[J].International Journal of Engineering Science,2007,45(2):698-715.
[18]伊盼盼,韦昌富,魏厚振,等.两种快速测定非饱和土水力学参数方法的对比分析[J].岩土力学,2012,33(7):2007-2012.
[19]Chen P,Wei C F,Yi P P,et al.Determination of hydraulic properties of unsaturated soils based on nonequilibrium multistep outflow experiments[J].Journal of Geotechnical and Geoenvironmental Engineering,2017,143(1)Doi:10.1061/(ASCE)GT.1943-5606.0001598.
[20]陈辉,韦昌富,陈盼,等.一种测定非饱和土-水力学参数的方法[J].岩土力学,2010,31(10):3348-3353.
[21]陈辉,韦昌富,胡国辉.利用溢出量数据确定非饱和土-水力学参数[J].岩土力学,2013,34(2):347-352.
[2]Vanapalli S K,Fredlund D G,Pufahl D E.The relationship between the soil-water characteristic curve and the unsaturated shear strength of a compacted glacial till[J].Geotechnical Testing Journal,1996,19(3):259-268.
[3]van Genuchten M T.A closed-form equation for predicting the hydraulic conductivity of unsaturated soils[J].Soil Science Society of America Journal,1980,44(5):892-898.
[4]Mualem Y.A new model for predicting the hydraulic conductivity of unsaturated porous media[J].Water Resources Research,1976,12(3):513-522.
[5]Fredlund D G,Xing A Q,Huang S Y.Predicting the permeability function for unsaturated soils using the soil-water characteristic curve[J].Canadian Geotechnical Journal,1994,31(4):533-546.
[6]傅鑫晖,韦昌富,颜荣涛,等.桂林雁山红黏土的土-水特征试验[J].桂林理工大学学报,2013,33(3):488-492.
[7]常红帅,刘丽,季春生,等.桂林、柳州两种红黏土的土-水特征曲线[J].桂林理工大学学报,2015,35(4):855-859.
[8]张爱伟,张家文,于明波,等.南宁地区非饱和残积黏土持水性试验[J].桂林理工大学学报,2018,38(1):112-116.
[9]Gardner W R.Calculation of capillary conductivity from pressure plate outflow data[J].Soil Science Society of America Journal,1956,20(3):317-320.
[10]Doering E J.Soil-water diffusivity by the one-step method[J].Soil Science,1965,99(5):322-326.
[11]van Dam J C,Stricker J N M,Droogers P.Inverse method for determining soil hydraulic functions from one-step outflow experiments[J].Soil Science Society of America Journal,1992,56(4):1042-1050.
[12]Eching S O,Hopmans J W.Optimization of hydraulic functions from transient outflow and soil water pressure data[J].Soil Science Society of America Journal,1993,57(5):1167-1175.
[13]Eching S O,Hopmans J W,Wendroth O.Unsaturated hydraulic conductivity from transient multistep outflow and soil water pressure data[J].Soil Science Society of America Journal,1994,58(3):687-695.
[14]Lu N,Wayllace A,Carrera J,et al.Constant flow method for concurrently measuring soil-water characteristic curve and hydraulic conductivity function[J].Geotechnical Testing Journal,2006,29(3):230-241.
[15]Hassanizadeh S M,Gray W G.Mechanics and thermodynamics of multiphase flow in porous media including interphase boundaries[J].Advances in Water Resources,1990,13(4):169-186.
[16]Wei C,Dewoolkar M M.A continuum theory of nonequilibrium two-phase flow through porous media with capillary relaxation[M]//Advances in Unsaturated Soil,Seepage,and Enviromental Geotechnics,2006:246-254.
[17]Wei C F,Muraleetharan K K.Linear viscoelastic behavior of porous media with non-uniform saturation[J].International Journal of Engineering Science,2007,45(2):698-715.
[18]伊盼盼,韦昌富,魏厚振,等.两种快速测定非饱和土水力学参数方法的对比分析[J].岩土力学,2012,33(7):2007-2012.
[19]Chen P,Wei C F,Yi P P,et al.Determination of hydraulic properties of unsaturated soils based on nonequilibrium multistep outflow experiments[J].Journal of Geotechnical and Geoenvironmental Engineering,2017,143(1)Doi:10.1061/(ASCE)GT.1943-5606.0001598.
[20]陈辉,韦昌富,陈盼,等.一种测定非饱和土-水力学参数的方法[J].岩土力学,2010,31(10):3348-3353.
[21]陈辉,韦昌富,胡国辉.利用溢出量数据确定非饱和土-水力学参数[J].岩土力学,2013,34(2):347-352.