一个非饱和结构性黄土三维胶结接触模型
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摘要
对非饱和结构性黄土进行离散元模拟需要合理的三维胶结接触模型。在含抗转动和抗扭转模型基础上引入了颗粒间吸引力以考虑范德华力和毛细力作用;提出了考虑胶结尺寸影响的胶结刚度和强度公式,考虑了不可恢复的化学胶结作用;建立了可以全面考虑含水率–孔隙比–吸力耦合作用的黄土接触模型。通过开展常规三轴压缩以及在不同偏应力水平下湿陷试验的三维离散元模拟,表明该三维接触模型可以较好地反映室内试验中非饱和结构性黄土的主要力学特性。
An adaptable three-dimensional(3D) contact model is necessary to perform discrete element simulation(DEM)on unsaturated structural loess, in which the effects of adhesive force and chemical cementation bond have to be taken into account.A 3DDEM contact model is introduced to simulate the macroscopic and microscopic mechanical behaviors of unsaturated and structural loess by considering the effects of adhesive force and chemical cementation. Interparticle adhesive force is composed of van der Waals attractions and capillary forces. Both bond stiffness and strength are associated with the bond size to represent unrecoverable chemical cementation. By using the relationships between water content and suction, a new 3D contact model for loess is established considering the coupling effects of water content-void ratio-suction. The DEM is used to simulate the triaxial and wetting tests at different deviator stress levels and the results show that the 3D contact model can well reproduce the macroscopic mechanical behaviors of unsaturated structural loess.
An adaptable three-dimensional(3D) contact model is necessary to perform discrete element simulation(DEM)on unsaturated structural loess, in which the effects of adhesive force and chemical cementation bond have to be taken into account.A 3DDEM contact model is introduced to simulate the macroscopic and microscopic mechanical behaviors of unsaturated and structural loess by considering the effects of adhesive force and chemical cementation. Interparticle adhesive force is composed of van der Waals attractions and capillary forces. Both bond stiffness and strength are associated with the bond size to represent unrecoverable chemical cementation. By using the relationships between water content and suction, a new 3D contact model for loess is established considering the coupling effects of water content-void ratio-suction. The DEM is used to simulate the triaxial and wetting tests at different deviator stress levels and the results show that the 3D contact model can well reproduce the macroscopic mechanical behaviors of unsaturated structural loess.
引文
[1]BARDEN L,MCGOWN A,COLLINS K.The collapse mechanism in partly saturated soil[J].Engineering Geology,1973,7(1):49-60.
[2]DELENNE J Y,EIYOUSSOUFI M S,CHERBLANC F,et al.Mechanical behaviour and failure of cohesive granular materials[J].International Journal for Numerical and Analytical Methods in Geomechanics,2004,28(15):1577-1594.
[3]JIANG M J,SUN Y G,LI L,et al.Contact behavior of idealized granules bonded in two different interparticle distances:An experimental investigation[J].Mechanics of Materials,2012,55:1-15.
[4]SHEN Z F,JIANG M J,WAN R.Numerical study of inter‐particle bond failure by 3D discrete element method[J].International Journal for Numerical and Analytical Methods in Geomechanics,2016,40(4):523-545.
[5]JIANG M J,SHEN Z F,WANG J F.A novel three-dimensional contact model for granulates incorporating rolling and twisting resistances[J].Computers and Geotechnics,2015,65:147-163.
[6]ITASCA.User manual of particle flow code[Z].2015.
[7]李涛.非饱和结构性黄土三维离散元模拟与本构模型研究[D].上海:同济大学,2017.(LI Tao.Three-dimensional DEMsimulation and constitutive model of unsaturated structural loess[D].Shanghai:Tongji University,2017.(in Chinese))
[8]JIANG M J,KONRAD J M,LEROUEIL S.An efficient technique for generating homogeneous specimens for DEMstudies[J].Computers and Geotechnics,2003,30(7):579-597.
[9]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.
[10]GARAKANI A A,HAERI S M,KHOSRAVI A,et al.Hydro-Mechanical behavior of undisturbed collapsible loessial soils under different stress state conditions[J].Engineering Geology,2015,195:28-41.
[11]张苏民,郑建国.力和水作用先后次序对湿陷性黄土力学性状的影响[J].勘察科学技术,1990,3:10-14.(ZHANG Su-min,ZHENG Jian-guo.Influence of order of force and water on mechanical properties of collapsible loess[J].Site Investigation Science and Technology,1990,3:10-14.(in Chinese))
[2]DELENNE J Y,EIYOUSSOUFI M S,CHERBLANC F,et al.Mechanical behaviour and failure of cohesive granular materials[J].International Journal for Numerical and Analytical Methods in Geomechanics,2004,28(15):1577-1594.
[3]JIANG M J,SUN Y G,LI L,et al.Contact behavior of idealized granules bonded in two different interparticle distances:An experimental investigation[J].Mechanics of Materials,2012,55:1-15.
[4]SHEN Z F,JIANG M J,WAN R.Numerical study of inter‐particle bond failure by 3D discrete element method[J].International Journal for Numerical and Analytical Methods in Geomechanics,2016,40(4):523-545.
[5]JIANG M J,SHEN Z F,WANG J F.A novel three-dimensional contact model for granulates incorporating rolling and twisting resistances[J].Computers and Geotechnics,2015,65:147-163.
[6]ITASCA.User manual of particle flow code[Z].2015.
[7]李涛.非饱和结构性黄土三维离散元模拟与本构模型研究[D].上海:同济大学,2017.(LI Tao.Three-dimensional DEMsimulation and constitutive model of unsaturated structural loess[D].Shanghai:Tongji University,2017.(in Chinese))
[8]JIANG M J,KONRAD J M,LEROUEIL S.An efficient technique for generating homogeneous specimens for DEMstudies[J].Computers and Geotechnics,2003,30(7):579-597.
[9]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.
[10]GARAKANI A A,HAERI S M,KHOSRAVI A,et al.Hydro-Mechanical behavior of undisturbed collapsible loessial soils under different stress state conditions[J].Engineering Geology,2015,195:28-41.
[11]张苏民,郑建国.力和水作用先后次序对湿陷性黄土力学性状的影响[J].勘察科学技术,1990,3:10-14.(ZHANG Su-min,ZHENG Jian-guo.Influence of order of force and water on mechanical properties of collapsible loess[J].Site Investigation Science and Technology,1990,3:10-14.(in Chinese))