岩土力学
巖土力學
암토역학
ROCK AND SOIL MECHANICS
2013年
11期
3299-3305
,共7页
李识博%王常明%马建全%王钢城
李識博%王常明%馬建全%王鋼城
리식박%왕상명%마건전%왕강성
黄土%三轴试验%颗粒流%微观变形
黃土%三軸試驗%顆粒流%微觀變形
황토%삼축시험%과립류%미관변형
loess%triaxial tests%particle flow%microscopic deformation
为了解黄土三轴剪切过程中的微观变化,采用PFC3D建立黄土三轴试验模型,模拟围压分别为0、50、150、300 kPa的三轴剪切试验,并与室内试验进行对比分析。分析结果表明:PFC3D能够较好地模拟出不同围压下从开始到破坏到残余变形整个过程中应力-应变的变化规律,且位移场及接触应力场的变化规律与室内三轴试验宏观现象较一致;发现弹性模量、泊松比及峰值强度与数值模型中微观参数有着密切的联系,如法向刚度 kn控制试样宏观弹性模量,kn/ks值控制泊松比,摩擦系数控制峰值强度;通过体应变-轴向应变曲线发现,随着围压的增加应变能增大,试样呈现出由体积膨胀到体积减缩的变化规律。其研究结果为进一步探究黄土的应力-应变性状及抗剪强度特性提供参考。
為瞭解黃土三軸剪切過程中的微觀變化,採用PFC3D建立黃土三軸試驗模型,模擬圍壓分彆為0、50、150、300 kPa的三軸剪切試驗,併與室內試驗進行對比分析。分析結果錶明:PFC3D能夠較好地模擬齣不同圍壓下從開始到破壞到殘餘變形整箇過程中應力-應變的變化規律,且位移場及接觸應力場的變化規律與室內三軸試驗宏觀現象較一緻;髮現彈性模量、泊鬆比及峰值彊度與數值模型中微觀參數有著密切的聯繫,如法嚮剛度 kn控製試樣宏觀彈性模量,kn/ks值控製泊鬆比,摩抆繫數控製峰值彊度;通過體應變-軸嚮應變麯線髮現,隨著圍壓的增加應變能增大,試樣呈現齣由體積膨脹到體積減縮的變化規律。其研究結果為進一步探究黃土的應力-應變性狀及抗剪彊度特性提供參攷。
위료해황토삼축전절과정중적미관변화,채용PFC3D건립황토삼축시험모형,모의위압분별위0、50、150、300 kPa적삼축전절시험,병여실내시험진행대비분석。분석결과표명:PFC3D능구교호지모의출불동위압하종개시도파배도잔여변형정개과정중응력-응변적변화규률,차위이장급접촉응력장적변화규률여실내삼축시험굉관현상교일치;발현탄성모량、박송비급봉치강도여수치모형중미관삼수유착밀절적련계,여법향강도 kn공제시양굉관탄성모량,kn/ks치공제박송비,마찰계수공제봉치강도;통과체응변-축향응변곡선발현,수착위압적증가응변능증대,시양정현출유체적팽창도체적감축적변화규률。기연구결과위진일보탐구황토적응력-응변성상급항전강도특성제공삼고。
In order to research microscopic changes of loess during triaxial shear process, the loess triaxial test model is established with PFC3D (particle flow code in 3 dimensions) software. And the triaxial shear tests are simulated under different confining pressures of 0 kPa, 50 kPa, 150 kPa and 300 kPa. Compared with the results of laboratory triaxial shear tests, the microscopic changes of particles from the beginning then to the peak and at last to the residual deformation of the stress-strain curve are simulated by PFC3D. And the variations of displacement field and contact stress field are more consistent with the macroscopic phenomena of laboratory triaxial tests. The researches indicate that some closely links are existed between the macroscopic parameters (elastic modulus, Poisson's ratio, peak strength) of laboratory model and microscopic parameters (normal stiffness, shear stiffness, friction coefficient) of numerical model. For example, the elastic modulus is controlled by the normal stiffness; the Poisson’s ratio is controlled by the ratio of normal stiffness and shear stiffness;the friction coefficient impacts on the peak strength of stress-strain curve. With the increase of confining pressure, strain energy increases and volume changes in expansion-to-reduction trend. The research result can provide some references for further study of stress-strain behavior and shear strength characteristics of loess.