静力触探试验的离散元数值模拟研究

由于静力触探试验的可重复性及可靠性,它在现场试验中被广泛应用。对静力触探试验进行颗粒流模拟,有助于从细观上了解静力触探试验机理,使之更好地服务于工程实际。颗粒流方法在模拟土体大变形方面具有一定的优势,本文利用颗粒流理论及其程序,首先在双轴试验的基础上确定了土样细观参数,然后建立静力触探的数值模型,模拟研究了贯入过程及锥尖土体的细观力学特征,重点分析了静力触探过程中砂土的位移运动规律,砂土的水平和垂直应力场及主应力的偏转。通过施加不同的应力边界条件,分析了模型不同的应力条件及超固结比(OCR)对锥尖贯入阻力的影响。同时,分析了锥尖尺寸效应对锥尖贯入阻力的影响规律。数值模拟结果与已有的试验规律具有较好的一致性,从而验证了颗粒流方法模拟静力触探试验的可行性,所得结论具有一定的理论价值和工程意义。

Numerical simulation of cone penetration test by discrete element method

The repeatability and reliability of the cone penetration test(CPT) have increased its acceptance as a predominant choice in in-situ test techniques.Using particle flow code in 2-dimension(PFC2D) to study the meso-mechanics of cone penetration test is a good way,and it will be helpful to the service for practical engineering.The discrete element method(DEM) method is of some predominance in the simulation of soil large deformation.Thus PFC2D program was applied here.The driving process of cone,the distribution of displacement and stress of adjacent soil were analyzed,and the isoline of displacement and stress field was drawn.At the same time,the rotation of principal stresses was analyzed.Especially,the stress boundary conditions were applied to different boundaries to obtain different stress states,and the emphasis was laid on the effect of different stress conditions and OCR on the cone tip resistance.The conclusions in this study would be useful to the model study of CPT and its engineering application.