SBISP-易扰动土界面摩擦特性及其力学响应研究

The pile foundation is used in the area of perturbable soil, how to make sure the interfacial friction and mechanical response between pile and soil is the key problem of pile design. Self-boring In-situ Shear Parameter (SBISP) has little disturbance to soil, the unique multi-stage compound loading method can be regarded a mode as “radial stress → radial strain → vertical stress → vertical strain”, which is helpful to study the interaction between pile and susceptible soil. Based on this new technology of SBISP, consider initial stress, pore water pressure and construction surface roughness, taking the analysis method of in-situ test combined with the hole imaging technique, the hole acoustic CT technique, the freezing method to take the soil samples for indoor CT scanning and scanning electron microscopy, visual model test supplemented by digital photography visual tracking technology, digital information processing technology, full scale model test to set different degrees of overburden pressure and numerical simulation. On the macroscopic, microscopic and microscopic scales, the friction characteristics and mechanical response of the interface of the perturbable soil under the condition of multi-stage compound loading. Based on the theory of circular hole expansion, intensity regeneration, the physical model of load transfer of friction pile and the theory of slip line field, the mechanical response of the interface of vulnerable soil under SBISP multi - stage compound loading is explained.

易扰动土地区工程多采用桩基础，如何确定桩土间的界面摩擦特性及其力学响应特征是桩基设计的关键问题。自主研发的自钻式原位剪切旁压仪（SBISP）对土体的扰动小，独特的多级复合加载方式可视为“径向应力→径向应变→竖向应力→竖向应变”的模式如此往复五次，对研究桩基与易扰动土间的相互作用有利。基于SBISP新技术，考虑初始应力、孔隙水压力、结构表面粗糙度等因素，采取：原位试验辅以孔内成像技术、孔内声波CT技术、冷冻法取试验后土样进行室内CT扫描与电镜扫描，可视化模型试验辅以数码摄影可视化跟踪技术与数字信息处理技术，足尺模型试验中设置不同程度的上覆土压力，数值模拟分析等综合方法，在宏观、细观及微观尺度上，量化研究多级复合加载条件下易扰动土界面的摩擦特性及其力学响应特征。基于圆孔扩张理论、强度再生理论、摩擦桩的荷载传递物理模型、滑移线场理论，对SBISP多级复合加载条件下易扰动土界面的力学响应进行解释。

自主研发的自钻式原位剪切旁压仪（SBISP）对土体的扰动小，独特的多级复合加载方式对研究桩基与易扰动土间的相互作用有利。基于SBISP新技术，考虑初始应力、孔隙水压力、 结构表面粗糙度等因素，采取：原位试验辅以孔内成像技术，可视化模型试验辅以数码摄影可视化跟踪技术与数字信息处理技术，数值模拟分析等综合方法，在宏观、细观及微观尺度上，量化研究多级复合加载条件下易扰动土界面的摩擦特性及其力学响应特征。基于圆孔扩张理论、强度再生理论和摩擦桩的荷载传递物理模型理论，对SBISP多级复合加载条件下易扰动土界面的力学响应进行解释。