考虑蠕变变形的格室加筋土力学性质研究

Investigation on the Mechanical Properties of Geocell-Reinforced Soil Considering Creep Effects

格室条带的蠕变变形会对土工格室的网格尺寸和条带刚度产生影响。采用加速蠕变试验和分级等温法(SIM法)建立了分别由HDPE(高密度聚乙烯)、PP(聚丙烯)和PET(聚对苯二甲酸乙二醇酯)三种材料制作的格室条带的主蠕变曲线和等时应力应变曲线,研究了蠕变对网格尺寸和条带长期刚度的影响。基于加筋土应力应变响应计算模型研究了格室条带的蠕变变形对加筋土强度和刚度的影响规律。结果表明,蠕变变形导致网格尺寸的增量较小,而长期刚度衰减主要在蠕变前期较明显;拉伸应变较小时,条带刚度随时间增加衰减较明显;因蠕变变形影响,格室加筋土的峰值偏差应力减小明显,其幅度范围约30%~55%;蠕变后加筋土变形模量的衰减随着轴向应变的增加逐渐明显。

The creep deformation of geocell strips will affect the grid size and strip stiffness of geocell.The main creep curves and isochronous stress-strain curves of lattice strips made of HDPE(high density polyethylene),PP(polypropylene)and PET(polyethylene terephthalate)were established by using accelerated creep test and SIM method.The effects of creep on mesh size and long-term stiffness of lattice strips were studied.Based on the stress-strain response calculation model of reinforced soil,the influence of creep deformation of lattice strips on the strength and stiffness of reinforced soil was studied.The results show that:The creep deformation results in a small increase in geocell mesh size,while the decrease of the long-term stiffness is obvious in the prophase of creep.The reduction of stiffness with time is significant at low tensile strain level.Due to the effects of creep,the peak deviatoric stress of reinforced soil decreases about 30%~55%.The reduction of deformation modulus induced by creep becomes noticeable with the increase of axial strain.