水射流辅助动力沉桩技术研究

Study on destruction of soil plug by water jet for auxiliarily driving a pile

水射流破坏桩内土塞辅助动力沉桩是一种有效处理土塞问题使桩达到标准贯入深度的辅助沉桩方法,而该项技术的关键是水射流对桩内土塞的破坏。借助理论分析、数值模拟和模型实验进行水射流破坏桩内土塞辅助动力沉桩研究。首先进行射流破坏土塞理论分析,定性地说明水射流破坏土塞能力与水射流压力、流量等参数有关;然后对不同形状喷嘴形成的射流的破坏土塞能力进行数值模拟,得到六种喷嘴射流作用下土塞内的最大、最小应力;再通过模型实验对有无射流辅助沉桩的沉桩锤击数进行对比,结果表明水射流辅助沉桩的锤击数少于无射流辅助沉桩的锤击数,说明水射流可用于辅助动力沉桩。最后设计出水射流破坏桩内土塞辅助动力沉桩工艺步骤。

The destruction of soil plug by water jet for auxiliarily driving a pile is an effective method which can destroy the soil plug and ensure the pile to be driven the standard penetration depth. The key of the technology is the destruction of the soil plug by water jet. The destruction of soil plug by water jet for auxiliarily driving a pile is studied with the theoretical analysis, the numerical simulation and the model test. Firstly, the destruction of soil plug by water jet is analyzed in theory and it is shown that the destruction ability of water jet is related to water jet parameters such as pressure and flow rate. And then the destruction ability of water jet produced by different shapes of nozzles is numerically simulated. The maximum and minimum stresses in soil plug under the effect of six kinds of nozzles are obtained. The hammer numbers of driving pile with and without water jet are compared in the model test, and it is shown that the hammer number of driving pile with and without water jet is less than the hammer number of driving pile without water jet. It is indicated that water jet can be used for auxiliarily driving a pile. At last, the process steps of the destruction of soil plug by water jet for auxiliarily driving a pile are designed.