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利用GDS应力路径三轴试验系统,开展不同围压下湛江强结构性黏土的三轴固结排水剪切蠕变试验,获得其轴向应变、体应变与应力和时间的关系,分析蠕变性状的结构性效应,建立相应的蠕变模型。结果表明,湛江黏土的蠕变变形演化特征受其强结构性制约,其蠕变特性的敏感程度与结构性强弱相关联。在低偏应力下,其蠕变变形和变形速率均较小;偏应力超过临界值后,土体在短时间内发生破坏。湛江黏土在σ3<σk时,其体变性状总体上表现为剪缩,但随时间变化出现一定的剪缩和剪胀交替性,即存在回弹现象;而当σ3≥σk时,则表现为剪缩。蠕变引起的强度衰减主要表现为黏聚力的降低,且c∞/ci=77.63%。采用6元件扩展Burgers模型能较好地描述湛江黏土的瞬时弹性应变、衰减蠕变和稳定蠕变3个阶段。在实际工程中,必须对土的结构性给予充分的认识,在较低应力范围内,可以利用其结构性的有利因素,但设计荷载严禁超出结构屈服应力。
Using the GDS stress path triaxial test system, the triaxial consolidation shear displacement creep test of Zhanjiang strong structural clay under different confining pressures was carried out to obtain the relationship between axial strain, body strain and stress and time, and the creep characteristics The structural effect, the establishment of the corresponding creep model. The results show that the creep deformation of Zhanjiang clay is controlled by its strong structural characteristics. The sensitivity of its creep properties is related to its structural strength. Under the low deviatoric stress, the creep deformation and deformation rate are both small. After the deviatoric stress exceeds the critical value, the soil body is damaged in a short time. The deformation of Zhanjiang clay shows shear shrinkage as a whole when σ3 <σk, but the change of shear-shrinkage and dilatancy appears alternately with time, that is, there is rebound phenomenon. When σ3≥σk, Scissors. The strength attenuation caused by creep mainly shows the decrease of cohesion, and c∞ / ci = 77.63%. The Burgers model with 6-element extension can well describe the transient elastic strain, attenuation creep and steady creep of Zhanjiang clay. In practical engineering, the structural nature of soil must be fully recognized, and its structural advantages can be utilized within the lower stress range, but the design load is forbidden to exceed the structural yield stress.