钙质砂中静力触探试验的大变形有限元模拟

Large deformation finite element analysis of cone penetration tests in calcareous sands

静力触探试验(CPT)被广泛用于确定无黏性土的力学性质,现有研究集中在普通石英砂,由CPT贯入阻力推测钙质砂强度特性的成果很少。钙质砂的峰值内摩擦角一般高于石英砂,内摩擦角和剪胀角随应变的变化也不同于石英砂。采用任意拉格朗日欧拉公式的大变形有限元方法,模拟石英砂和钙质砂中CPT的完整贯入过程,有效避免了锥尖周围的网格扭曲。引入修正摩尔-库伦模型描述石英砂和钙质砂强度发挥与塑性剪应变的关系,由弯曲元和三轴排水试验确定本构模型参数。数值模拟得到的锥尖贯入阻力与离心机试验结果吻合,表明建立的数值模型能够模拟钙质砂中的CPT试验。

The cone penetration test(CPT)is widely used to determine the mechanical properties of cohesionless soils.Most of the existing correlations were established in terms of silica sands,while the data for calcareous sands are limited.In comparison to silica sands,calcareous sands have a higher peak internal friction angle and the variation of the friction angle and the dilation angle with strain in calcareous sands is also different from silica sands.In this paper,the Arbitrary Lagrangian Eulerian method and a large deformation finite element approach,was used to study cone penetration in calcareous and silica sands.Frequent mesh generations were conducted to avoid the distortion of soil elements around the cone tip.A modified Mohr-Coulomb constitutive model was introduced to describe the mobilized strength varied with the plastic shear strain in calcareous and silica sands.The elastic and plastic parameters were determined by bender element tests and drained triaxial tests.Numerical results of cone tip resistance agree reasonably well with the existing data from centrifuge tests,showing that the established numerical model has the potential to simulate the cone penetration in calcareous sands.