基于光纤布拉格光栅传感技术的开口管桩贯入特性实验研究

Experimental Study on Penetration Characteristics of Open Pipe Pile Based on Fiber Bragg Grating Sensing Technology

为探索光纤布拉格光栅(FBG)传感技术在开口管桩贯入特性实验研究中的适用性,用一种增敏微型FBG应变传感器,对室内模型中开口管桩在沉桩过程中的受力状态进行了监测。研制了一种可拆卸的双壁开口模型管桩,将FBG传感器通过刻槽埋设和桩壁粘贴法安装在模型管桩上,测得模型管桩在贯入过程中的应力分布及变化规律。实验结果表明,该传感器配合特制的模型管桩,能满足开口管桩贯入特性的测试要求,且安装方便、存活率高。随模型管桩贯入深度的增加,开口管桩呈摩擦端承桩的承载特性,桩身内壁、外壁监测点处的轴力均增大,但各点增长速率存在差异;桩内壁、外壁侧摩阻力整体呈增大趋势,单位侧摩阻力出现不同程度的“退化效应”。

In order to explore the applicability of fiber Bragg grating(FBG)sensing technology in the experimental study of the penetration characteristics of open pipe pile,a sensitized miniature FBG strain sensor is used to monitor the stress state of the open pipe pile during the pile sinking process in the indoor model test.A detachable double-walled open model pipe pile is made,the FBG sensors are mounted on the model pipe pile by grooving and gluing the pile wall.The stress distribution and variation law of the model pipe pile during penetration are measured.The results indicate that the sensors with the special model pipe pile can better meet the requirements for testing the penetration characteristics of the open pipe pile.The sensors are easy to install and have a high survival rate.With the increase of the penetration depth of the model pipe pile,the bearing characteristic is similar to the friction end-bearing piles,and the axial forces of the inner and outer walls of the pile increase,but the growth rate of each point is different.The lateral frictional resistance of the inner and outer wall of the pile increases as a whole,and the unit side frictional resistance shows different degrees of“degradation effect”.