等向强化–软化Drucker-Prager材料强度参数演化

Drucker-Prager屈服准则中压力相关系数α和黏聚剪切强度k的实测结果少有报道。根据同一组致密砂岩三轴压缩试验,同时测试Mohr-Coulomb准则中的内摩擦角φ和黏聚力c以及Drucker-Prager准则中的压力相关系数α和黏聚剪切强度k。测试结果显示,描述岩石内摩擦性质的参数φ和α随着塑性变形的增长而增长,但是增长速率逐渐减小;描述岩石胶结性质的参数c和k在岩石初始屈服后会先上升至峰值,然后随着塑性变形的增长从峰值逐渐下降。同时,从5种常用的Mohr-Coulomb准则与Drucker-Prager准则转换关系中,通过同一组三轴压缩试验结果寻找到吻合程度最高的换算关系。Drucker-Prager材料强度参数的变化将来可应用到岩土类材料的数值计算中来模拟材料的强化和软化性质,同时也可以为Mohr-Coulomb准则参数与Drucker-Prager准则参数转换提供一定参考。

Variation of strength parameters of Drucker-Prager material with isotropic hardening and softening

The experimental research on the strength parameters of Drucker-Prager criterion, i.e. the coefficient of pressure sensitivity and the shearing strength of cohesion ，was rarely reported. The parameters including the internal friction angle ，the cohesion ，the coefficient of pressure sensitivity and the shearing strength of cohesion were measured simultaneously with the same group of triaxial compression tests on dense sandstone. The results show that and gradually increase with the plastic deformation in a decreasing rate，while and firstly increase to their peak values and then decrease with the plastic deformation. Five pairs of mostly used parameter conversion formulae for Mohr-Coulomb criterion and Drucker-Prager criterion were compared so that a pair of best fit conversion formulae were found with the same group of triaxial compression tests. The variation of strength parameters in Mohr-Coulomb criterion and Drucker-Prager criterion can be used to simulate the hardening and softening of geomaterials in the future numerical computation of geotechnical engineering.