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针对天然强结构性湛江黏土,通过开展不同静偏应力影响下的不排水循环加载三轴试验,对循环荷载作用下的动变形、动强度和动孔隙水压力特性以及与土结构性间的内在联系进行系统性的试验研究。结果表明,结构性黏土在循环荷载作用下的突然破坏,具有脆性破坏特征,静偏应力越大,土体破坏应变越小。湛江黏土的临界动应力随静偏应力呈先增大、后减小的变化规律,在静偏应力较小时存在峰值。分析认为,静偏应力对结构性黏土动力特性的影响存在分界值,小于该值时静偏应力对土体的压密作用提高了土体的临界动应力和动强度,抑制了土的变形发展;当静偏应力继续增大,则土体结构损伤,动荷载下的临界动应力和动强度均呈下降趋势。结构性土的动孔隙水压力低于一般黏土,静偏应力的存在导致孔压在土体破坏后出现负增长,初始剪应力使结构性土体产生剪胀势。
Aiming at the natural strong structural Zhanjiang clay, the dynamic deformation, dynamic strength and dynamic pore water pressure under cyclic loading and the relationship between the inherent pore structure and the soil structure are studied by carrying out the undrained cyclic loading triaxial test under the influence of different static deviatoric stress Contact for systematic pilot studies. The results show that the structural clay has a sudden failure under cyclic loading and has the characteristics of brittle failure. The larger the static deviatoric stress is, the smaller the soil strain is. The critical dynamic stress of Zhanjiang clay increases first with static deviatoric stress and then decreases with the increase of static deviatoric stress. The analysis shows that the static deviatoric stress has a demarcation value on the dynamic characteristics of structural clay. When the value is lower than this value, the densification effect of static deviatoric stress on the soil mass increases the critical dynamic stress and dynamic strength of the soil and suppresses the deformation and development of the soil When the static deviatoric stress continues to increase, the damage of soil structure and the critical dynamic stress and dynamic strength under the dynamic load show a decreasing trend. The dynamic pore water pressure of structural soil is lower than that of normal clay. The existence of static deviatoric stress causes the pore pressure to negatively increase after the soil failure, and the initial shear stress causes the dilatancy of the structural soil.