基于圆形断面自由紊动射流理论的旋喷桩直径计算方法

An approach to calculate diameter of jet-grouted columns based on turbulent flow theory

基于圆形断面自由紊动射流理论,提出了一种新的高压旋喷桩直径计算方法。考虑高压旋喷技术的施工过程,旋喷桩直径主要与施工场地的土性条件以及施工时的旋喷参数有关。从高压旋喷技术机理来看,高压水或水泥浆对土体的切割作用会产生一个切割距离,考虑工程实际的需要,该切割距离可以认为基本等于旋喷桩半径,通过对圆形断面紊动射流和土体破坏的联合分析,建立了旋喷桩半径、土性条件以及旋喷施工参数之间的关系。最后通过与现场实测数据的对比验证了该计算方法的实用性。

Based on the theory of turbulent kinematic flows, a simple approach to predict the diameter of jet-grouted column is proposed. Considering the process of jet grouting, the diameter of the jet-grouted columns is related to in-situ properties of soil and the jetting parameters adopted during construction. Since the fluid with high speed is jetted out from a nozzle to erode the soil during jet grouting, and there exists an erosion distance produced in the soil, the diameter can be estimated from this erosion distance. Through the analysis of free jet from a round nozzle and soil erosion, the erosion distance is obtained. Thus, the relationship among column diameter, jet parameters and soil properties can be established. Moreover, comparison between the predicted results and the data from literatures are also presented, and the results are classified according to the different soil types, which suggests that the proposed method is applicable for most soil types.