邻近斜坡静压沉桩挤土效应试验

Model Test on Squeezing Effect During Static Pressure Pile-sinking Adjacent to Slope

为了给邻近斜坡条件下的沉桩设计与施工提供参考,采用改装后的静力触探仪作为沉桩加载设备,对邻近斜坡沉桩挤土进行试验研究。试验装置主要由主体结构、加载系统、土压力测试系统以及位移量测设备组成,具有可确保模型桩连续贯入土体、实现对沉桩速率进行控制、实时监控桩侧挤土压力、动态追踪沉桩过程中桩侧挤土位移等特点。试验结果表明:在桩体贯入过程中,挤土位移的影响范围不断增加,桩周土体的位移模式也随之变化;距桩体及桩端较近范围内的土体,在桩体径向挤压和桩侧摩擦的共同作用下,产生了向下的位移;距桩体距离较远的土体,由于地表及斜边自由边界的存在,表现为竖向隆起位移;在沉桩达到一定深度后,后续沉桩对挤土位移影响较小。研究结果揭示了邻近斜坡沉桩挤土力学响应与坡体变形的内在机理,可为实际工程设计、施工参数设置以及挤土位移控制提供参考。

In order to provide reference for design and construction of pile-sinking adjacent to slope, using the modified static cone penetration equipment as loading system, the squeezing effect during pile-sinking adjacent to slope was studied. This test equipment is composed of main structure, loading system, soil pressure measuring system and displacement measuring system, with the following features： enabling the model pile to penetrate continuously into the soil; controlling the speed of pile sinking; monitoring the soil squeezing pressure and tracing the process of soil squeezing displacement during pile-sinking. The results indicate that the size of the influence zone, in which soil squeezing displacement is obvious, continues to increase with the penetration of pile, and the displacement mode around pile changes as well; the soil adjacent to the pile body settles downward under the radial compression and side friction; however, beyond a certain distance to pile body, heave displacement of the soil is observed due to the free boundary of surface and slope; after the pile reaches the bottom surface of the slope, the subsequent pile sinking has little influence on soil squeezing displacement. The experimental results reveal the soil squeezing performance caused by pile-sinking adjacent to slope and the mechanism for slope deformation, and provide a reference for practical engineering designing, construction parameters setting and soil squeezing displacement controlling.