双层高岭黏土中沉桩特性模型试验

为了揭示黏土中静压沉桩的宏观力学特性，采用西澳大学的梁式离心机压桩系统，通过在双层高岭黏土中进行一系列1g重力场情况下的T-bar触探测试试验、静压沉桩试验、桩拉伸试验和压缩试验，对比分析了T-bar分别在均质软质黏土和双层黏土中随贯入深度变化测得的不排水剪切强度的特性；研究了桩体在贯入过程中沉桩阻力、桩端阻力以及桩侧摩阻力的发展规律；并对桩身径向总应力在沉桩过程中的变化规律进行了探讨；此外，还揭示了不同桩型沉桩终压力与桩承载力之间的关系。结果表明：在黏土中沉桩时，桩侧摩阻力在整个沉桩阻力中发挥主要的作用；对于同一土层而言，当桩超过土层分界面以下2D（D为桩径）范围后，桩端阻力并不受相邻土层性质的影响；随着压桩后时间的推移，桩侧摩阻力对承载力的时效影响较桩端阻力大。

Lateral Stress for Model Jacked Piles in Two-Layered Kaolin Clay

The beam centrifuge pile-jacking system of the University of Western Australia was employed to carry out the penetration mechanism of jacked pile in clay. A series of T-bar tests, sinking pile tests, pile tensile tests and pile compression tests were made in two-layered kaolin clay. The comparison and analysis were conducted to the applications of T-bar in homogeneous soft clay and in two-layered clay by measuring the undrained shear strength with different penetration depth. The profiles of penetration resistance, end resistance and shaft resistance during the pile installation as well as the changing of pile radial stresses during the pile installation were investigated. The different relationships between pile final pressure and pile bearing capacity were revealed. The results show that shaft resistance plays a major role in the whole pile penetration resistance in clay; for the same soil layer, the pile end resistance is not affected by the properties of adjacent soil layers when the pile end exceeds a certain range of influence below the soil interface; in addition, the time effect of pile shaft friction on bearing capacity is greater than that of end resistance.