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密实和松散颗粒材料等吸力三轴剪切试验离散元数值模拟

期刊名称：中南大学学报(自然科学版)
时间：2010.12.26
页码：2350-2359
分类：TU441.32[建筑科学—岩土工程;建筑科学—土工工程]
作者机构：[1]同济大学地下建筑与工程系,上海200092, [2]同济大学岩土及地下工程教育部重点实验室,上海200092
相关基金：国家自然科学基金资助项目（10972158）; 国家杰出青年基金资助项目（51025932）
相关项目：岩土力学与岩土工程

关键词：非饱和土, 离散元, 吸力, 抗剪强度, 组构, 配位数, unsaturated soil, discrete element method, suction, shear strength, fabric, coordination number

中文摘要：

从宏微观角度应用离散元研究吸力对密实和松散颗粒材料强度的影响。应用分层欠压法生成固定孔隙比的密实和松散长方体试样（长-宽-高=1-1-2）,在不同围压下固结,基于作者提出的相似理论,将吸力接触模型植入PFC3D中,计算吸力引起的颗粒间作用力。在等围压和等吸力下,对长方体试样进行三轴剪切试验,测得在剪切过程中轴向应力、轴向应变等宏观量和平均配位数、接触组构等微观量。研究结果表明：吸力能提高土的抗剪强度,提高试样的平均配位数;随着竖向应力增大,颗粒间接触主方向向竖直方向偏转;在相同吸力下,围压越大,接触点数越多,由吸力引起的抗剪强度越大。

英文摘要：

The effect of suction on the strength of unsaturated dense and loose granulates from macro and micro view was investigated by three-dimensional discrete element method（DEM）.The samples were generated by multi-layer with undercompaction method and then consolidated under different confining pressures.Based on the similarity theorem,the suction contact model was implemented into a three-dimensional DEM software to calculate interparticle force due to capillary water.Triaxial shear tests were performed on the cubic unsaturated samples to study shear strength of samples.Macroscopic variables（e.g.,axial stress,axial strain） and microscopic variables（e.g.,average coordination number,contact fabric） during shear test under different consolidation stresses with different suctions were measured.The results show that suction leads to higher shear strength and average coordination number of granulates than dry granulates.When the vertical load increases,the main contact orientation moves towards the vertical direction.Under the same suction,the numbers of contact points and shear resistance due to capillary water increase with the confining pressure.