粗粒料三轴试验橡皮膜嵌入量数值模拟

在粗粒料三轴试验中，橡皮膜嵌入量可造成显著的体积变形量测误差。本文针对颗粒材料的接触特点，利用Nagata Patch方法重建颗粒表面，基于重建曲面进行接触状态的判断和接触几何信息的计算，开发了高效的颗粒接触算法。该法采用dual mortar有限元方法处理颗粒与橡皮膜间的接触模拟，针对橡皮膜变形较大的特点，采用更新坐标的大变形计算格式，并根据重建的颗粒表面对颗粒-橡皮膜的距离进行几何修正，实现了颗粒-橡皮膜接触的精细化模拟，可较好地模拟计算“柔性”橡皮膜嵌入颗粒孔隙的过程。进行了Kramer钢球试验以及粗颗粒料和标准粗砂三轴试验橡皮膜嵌入过程的模拟计算，计算结果符合一般规律，与相应的试验结果吻合较好，验证了本文方法对于粗粒料膜嵌入问题的适用性。

Numerical simulation of rubber membrane penetration depth in triaxial tests of coarse-grained materials

Rubber membrane penetration can cause significant errors in volumetric deformation measurement in the triaxial test of coarse-grained materials. Considering the characteristics of particle contact, this paper presents an efficient algorithm for detecting particle contact state based on the particle surface that is reconstructed using the Nagata patch method. We simulate particle-membrane contact using a dual mortar method and a large geometric deformation algorithm, and modify the particle-membrane film distance based on the particle surface reconstruction. Hence, refined simulation of particle-membrane contact is realized and the penetration process of a flexible rubber membrane can be calculated. Simulations are carried out to study the membrane penetration processes in Kramer’s steel ball test, coarse-grained triaxial test, and standard coarse sand triaxial test. The calculation results are consistent with the general rules and agree well with the test results, indicating that our method is applicable to simulation and analysis of the membrane penetration process of coarse-grained particles.