自钻式原位剪切旁压模型试验颗粒流模拟

PFC NUMERICAL SIMULATION OF SELF-BORING IN-SITU SHEAR PRESSUREMETER MODEL TEST

基于颗粒流理论思想,应用PFC3D程序对自钻式原位剪切旁压模型试验(SBISP)进行了仿真模拟。以室内模型试验为基础,建立数值模型,模拟了自钻式原位剪切旁压试验加载过程,通过与SBISP试验曲线对比,验证了数值模型的有效性,分析了复杂加载条件下探头周围土体的位移发展模式和细观力学响应。数值试验结果表明,随着剪切应力的逐级施加,中间区域颗粒的位移量不断增大,并且位移矢量的方向性也更加显著,在第五级剪切应力作用下,受影响区域位移矢量形状为一倒锥形;而且剪切应力变化与探头摩擦系数有关,当摩擦系数达到某一值时,剪切应力-位移曲线不再发生变化。

The selfboring insitu shear pressuremeter model test is simulated by particle flow theory and PFC3D （Particle Flow Code in three Dimensions） program. Based on indoor model test, a numerical model is formed in PFC3D. The loading procedure of SBISP test is simulated. A comparison between numerical and experimental results shows reasonable agreement. The displacement development mode and mesomechanics response of soil grains a round the probe are studied under complex loading conditions. The numerical results show that the displacement of particles in central area increase with the shear stress imposed stepwise, and the direction of displacement vector is more significant too. The sape of displacement vector in influence area is a reverse cone under the fifth grade shear stress. The magnitude of shear stress depends on the friction coefficient of the probe, the shear stressshear dis placement curve is no longer changes when it reaches a certain value.