可燃冰沉积物三轴压缩模拟仿真试验分析

Numerical Simulation Experiment on Combustible Ice-Bearing Sediment

摘要: 利用颗粒流软件PFC3D制备了在不同可燃冰饱和度情况下可燃冰沉积物的数值仿真试样，对不同可燃冰饱和度下的可燃冰沉积物进行了三轴压缩模拟仿真试验，分析了可燃冰饱和度对可燃冰沉积物力学特性的影响。研究结果表明：可燃冰沉积物的初始弹性模量、峰值应力和残余强度均随可燃冰饱和度的增加而增大；在应力超过峰值应力后可燃冰沉积物出现明显的应变软化现象，在可燃冰饱和度小于20%时，应变软化开始时的轴向应变随饱和度增加而增大，在可燃冰饱和度大于20%时，应变软化开始时的轴向应变随饱和度的增加而减小；可燃冰沉积物表现出先剪缩后剪胀的趋势，并且剪胀现象随着可燃冰饱和度的增加而愈发明显。本文工作可为燃冰的安全开采，提供必要的力学基础与技术参考。

Abstract: Numerical simulation samples of combustible ice-bearing sediment are generated by the particle flow software PFC3D. Triaxial compression simulation experiments are carried out on the combustible ice-bearing sediment with various saturations of combustible ice to investigate the influences of combustible ice saturation on the mechanical behaviors of combustible ice-bearing sediment. The findings are as follows. The initial elastic modulus, peak stress and residual strength of combustible ice-bearing sediment increase upon the increased combustible ice saturation. There is strain softening phenomenon appearing in the combustible ice-bearing sediment when the material stress is above peak stress. The value of axial strain at the starting point of strain softening increases with the combustible ice saturation increasing when the value of combustible ice saturation is below 20%, while it decreases with the combustible ice saturation increasing when the value of combustible ice saturation is above 20%. There is a phenomenon of shearing shrinkage followed by a phenomenon of shear expansion in the combustible ice-bearing sediment during the process of triaxial compression loading. The phenomenon of shear expansion becomes clearer when the combustible ice saturation is increased. This work can provide the basis of mechanics and technical references for the safe mining of combustible ice.