福州淤泥质土动力特性室内试验研究

EXPRIMENTAL STUDY ON DYNAMIC CHARACTERISTICS OF MUDDY SOIL IN FUZHOU

沿海高速公路、铁路和地铁的迅速发展,使得长期循环荷载作用下的软基变形问题日渐突出。借助GDS动三轴仪,对福州淤泥质土进行动三轴试验。研究了不同围压下淤泥质土在循环荷载作用下的动应变、动强度、动剪切模量和阻尼比特性,重点分析了固结围压和动应力幅值对淤泥质土动强度的影响,由此建立了围压、振次与土体动强度的经验关系,该关系可用以估算不同深度土体在循环荷载作用下的动强度。试验结果表明：福州淤泥质土的动强度随着围压增加而增加,随着振次的增加而减小,且强度很低,动黏聚力的大小为0.3~4.0k Pa,动内摩擦角的大小为7°~10°。此外,给出了淤泥质土在大应变条件下的动剪切模量和阻尼比。研究结果对进一步认识该地区淤泥质土的动力特性以及对实际工程设计中合理选择土的动强度参数具有理论及实际意义。

As the rapid development of highway,railway and urban rail transit project,soft ground settlement caused by the long-term cyclic dynamic load has been paid more and more attention. The dynamic triaxial tests to measure the dynamic characteristic of muddy soil were conducted on samples from Fuzhou. A series of changing regulations of dynamic stress,dynamic strength,dynamic shear modulus and damping ratios were analyzed. The effects of consolidation pressure and dynamic stress amplitude on the dynamic strength of muddy soil were investigated respectively. A relationship among dynamic strength,consolidation pressure and vibration numbers is developed,by which the dynamic strength of soil in different depth can be estimated. The experimental results show that,the dynamic strength falls as the cycle of the dynamic loading increases,and it increases as consolidationpressure increases. It should be noticed that the values of dynamic strength is low. Finally,the values of dynamic shear modulus and damping ratios are given.