稳态流下非饱和土地基承载力模型
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摘要
基于稳态流下吸应力剖面具有明显非线性的特点,在仅考虑竖向稳定渗流条件下,通过补充普朗德尔假定,利用刚体平衡方法,推导普朗德尔滑动面范围内滑动土体稳态流下非饱和土地基的极限承载力计算模型,讨论地下水埋深和比流量变化对地基极限承载力的影响。结果表明:稳态流下非饱和土地基的极限承载力公式考虑了滑动土体内吸应力非线性分布特点对地基极限承载力的影响;当土体内吸应力随深度增加呈现出先增大后减小的特点时,地基极限承载力随地下水位埋深减小呈先减后增的变化趋势;当滑动土体内吸应力随比流量的增大呈现先增后减的趋势时,地基极限承载力呈现先减小再增大的变化趋势。
The suction stress profile is of obvious nonlinear characteristics under steady flow condition.This study supplemented the Prandtl assumption under the condition of considering the single vertical seepage and deduced the calculation model of bearing capacity for foundation of unsaturated soil under steady flow condition by means of rigid body balance method in the range of Prandtl sliding surface.It also discussed the influence of change of the groundwater and ratio flow on bearing capacity.The results show that the bearing capacity formula of unsaturated soil foundation under steady flow can take into account the influence of the nonlinear distribution of the soil suction stress;when suction stress increases firstly,and then decreases with the depth,the bearing capacity decreases first,and then increases as groundwater lever is lowered.
The suction stress profile is of obvious nonlinear characteristics under steady flow condition.This study supplemented the Prandtl assumption under the condition of considering the single vertical seepage and deduced the calculation model of bearing capacity for foundation of unsaturated soil under steady flow condition by means of rigid body balance method in the range of Prandtl sliding surface.It also discussed the influence of change of the groundwater and ratio flow on bearing capacity.The results show that the bearing capacity formula of unsaturated soil foundation under steady flow can take into account the influence of the nonlinear distribution of the soil suction stress;when suction stress increases firstly,and then decreases with the depth,the bearing capacity decreases first,and then increases as groundwater lever is lowered.
引文
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[15]LU N,LIKOS W J.Unsaturated soil mechanics[M].New York:John Wiley&Sons,2004.
[2]TANG Y,TAIEBAT H A,RUSSELL A R.Bearing capacity of shallow foundations in unsaturated soil considering hydraulic hysteresis and three drainage conditions[J].International Journal of Geomechanics,2017,17(6):1-13.
[3]GHORBANI J,NAZEM M,CARTER J P.Numerical modelling of multiphase flow in unsaturated deforming porous media[J].Computers and Geotechnics,2016,71:195-206.
[4]付建新,谭玉叶,宋卫东.崩落法开采塌陷区上覆黄土层降雨入渗机理研究[J].中国矿业大学学报,2015,44(2):349-352.FU J X,TAN Y Y,SONG W D.Study on mechanism of rainfall infiltration through overlying loess formation on block caving collapse area[J].Journal of China University of Mining&Technology,2015,44(2):349-352.(in Chinese)
[5]ZHANG Z Y,WANG W K,YEH T C J,et al.Finite analytic method based on mixed-form Richards'equation for simulating water flow in vadose zone[J].Journal of Hydrology,2016,537:146-156.
[6]ZHANG Z Y,WANG W K,CHEN L,et al.Finite analytic method for solving the unsaturated flow equation[J].Vadose Zone Journal,2015,14(1):1-10.
[7]PEDROSO D M,WILLIAMS D J.A novel approach for modelling soil-water characteristic curves with hysteresis[J].Computers and Geotechnics,2010,37(3):374-380.
[8]张常光,范文,赵均海.非饱和土强度统一解及地基承载力的拓展研究[J].中国矿业大学学报,2016,45(5):937-943.ZHANG C G,FAN W,ZHAO J H.Developments of unified solution of strength and bearing capacity of foundation in unsaturated soils[J].Journal of China University of Mining&Technology,2016,45(5):937-943.(in Chinese)
[9]张常光,范文,赵均海,等.线性吸力下非饱和土地基临界荷载统一解[J].中南大学学报(自然科学版),2016,47(12):4190-4197.ZHANG C G,FAN W,ZHAO J H,et al.Unified solution of critical load for foundation in unsaturated soils under linear suction[J].Journal of Central South University(Science and Technology),2016,47(12):4190-4197.(in Chinese)
[10]李艳,赵均海,张常光.非饱和土条形地基太沙基极限承载力三剪统一解[J].岩土力学,2015,36(11):3128-3134.LI Y,ZHAO J H,ZHANG C G.Triple-shear unified solution of terzaghi's ultimate bearing capacity for unsaturated soil foundation[J].Rock and Soil Mechanics,2015,36(11):3128-3134.(in Chinese)
[11]马少坤,扈萍,秦会来.刚柔性条形基础下非饱和土地基的承载特性[J].广西大学学报(自然科学版),2010,35(4):649-654.MA S K,HU P,QIN H L.Bearing capacity research on unsaturated subsoil under flexible and rigid shallow foundations[J].Journal of Guangxi University(Natural Science Edition),2010,35(4):649-654.(in Chinese)
[12]孟长江.考虑吸力的非饱和黏性土地基承载力分析[J].路基工程,2009(5):141-142.MENG C J.The foundation bearing capacity of unsaturated cohesive soil considered suction stress[J].Subgrade Engineering,2009(5):141-142.(in Chinese)
[13]侯建军,刘利星,赵天宇.非饱和原状黄土浸水前后地基承载力测试研究[J].工程勘察,2017(3):6-12.HOU J J,LIU L X,ZHAO T Y.Research on subgrade bearing capacity for unsaturated intact loess before and after immersion[J].Geotechnical Investigation&Surveying,2017(3):6-12.(in Chinese)
[14]李广信,张丙印,于玉贞.土力学[M].北京:清华大学出版社,2014:228-239.LI G X,ZHANG B Y,YU Y Z.Soil mechanics[M].Beijing:Tsinghua University Press,2014:228-239.(in Chinese)
[15]LU N,LIKOS W J.Unsaturated soil mechanics[M].New York:John Wiley&Sons,2004.