摘要
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。
Undrained cyclic triaxial tests are conducted on Zhanjiang structured clay under different static deviatoric stresses. The internal connection among dynamic deformation, dynamic pore pressure, dynamic strength and structure characteristics are studied. It is shown that the sudden destruction of structured clay under dynamic loads exhibits a feature of brittle failure; and the higher the static deviatoric stress, the smaller the failure strain. The trend of critical dynamic stress with deviatoric stress first increases and then decreases, and the critical dynamic stress has a peak value as the deviator stress decreases. There exists a threshold for the influence of static deviatoric stress on the dynamic characteristics of structured clay. If the static deviatoric stress is below the threshold, the deformation of the clay is restrained as a result of the improvement of the critical dynamic stress and the dynamic strength by the compaction effect of the static deviatoric stress. With the increasing of static deviatoric stress, however, the critical dynamic stress and dynamic strength decrease due to the damage of soil structure. The dynamic pore pressure of structured soil is slower than that of general soil, thus, and it drops after soil fails. The initial shear stress can increase the dilatancy.
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2017年第1期33-40,共8页
Rock and Soil Mechanics
基金
国家自然科学基金项目(No.51179186)~~
关键词
结构性黏土
静偏应力
动变形
临界动应力
动强度
动孔压
structured clay
static deviator stress
dynamic deformation
critical dynamic stress
dynamic strength
dynamic porepressure
