Temporal-spatial distribution characteristics and prediction model of pressures around rectangular pipe jacking in sand layer

The distribution characteristics of pressures around pipes are the basis for calculating the jacking force, friction resistance, internal force and mud permeability. However, there are few researches on rectangular pipe jacking. Based on a rectangular pipe jacking project, the pressure are monitored at different locations around the pipe during construction. The temporal and spatial variation characteristics of the pressures are analyzed, and the prediction model for the pressures in the process of permeability of mud is established. The method for calculating the related parameters is proposed based on the pipe-soil contact state and mechanical characteristics, and the predicted values by this model are compared with the measured ones. The results show that the pressures experience rapid growth stage, rapid decline stage and slow decline stage in the process of grouting-filtration. The pressures and change rates at the same depth are basically the same, but the pressures as well as their stability values and change rates at different depths are different. Meanwhile, the pressures at each location around the rectangular pipe conform to logarithmic regression function at mud filtration cycle. The calculation of the relevant parameters takes into account the engineering parameters such as soil properties, buried depth, groundwater pressure, pipe weight, mud buoyancy and actual grouting pressure. It is suitable for predicting the contact pressures of similar rectangular pipe jacking projects.