Analysis of fluidized zone in transparent soil under jet induced by pipe leakage

Jets caused by burst tubes erode the surrounding soil, eventually leading to issues such as ground collapse. It is therefore highly important to study the mechanisms of soil erosion caused by jets after pipeline leakage. To investigate the water-soil interaction mechanisms of pipe leakage, this study used transparent soil and developed a three-dimensional experimental device to observe the fluidization process. Changes in the boundary of the fluidization transition area were investigated, and a formula for calculating the soil damage area was derived. The results showed three different shapes of the fluidized cavity appearing in the fluidization process. The particles initially moved upward and then gradually transitioned into a state of backflow. The effects of particle size, upper load, and porosity on fluidization were also analyzed. It was found that soil with a large particle size and a lower porosity under a heavy upper load can effectively restrain fluidization. Therefore, large-diameter and dense soil can be used as pipe-covering material.

Visualization and digitization of model tunnel deformation via transparent soil testing technique

With the increasing demand for transportation infrastructure,the construction of urban tunnel systems linking different areas is indispensable.The deformation and the failure process during a tunnel excavation are essential concerns for geotechnical engineers.However,few studies have systematically investigated the effect of the ground loss ratio on tunnel deformation and the inequality between the ground loss ratio and the volume of the settlement trough.An experimental study using the transparent soil testing technique is performed herein for better visualization and digitization purposes.The three dimensional vertical and horizontal deformation patterns of a single tunnel are investigated for both the surface and the stratum right below considering different ground loss ratios.The relationship among the empirical constant of the settlement trough width,buried depth,depth-diameter ratio,and ground loss ratio is presented.

Review of transparent soil model testing technique for underground construction:Ground visualization and result digitalization

In geotechnical engineering,the transparent soil(also called transparent media)technique is an effective tool for conducting experimental tests and investigating the displacement characteristics and stress distribution of soils.It plays a vital role in the observation of internal soil deformations.This study aims to briefly review the current state of some of the common materials used to formulate transparent soil models and the application of the transparent soil technique to underground construction over the last 20 years.To this end,the basic concepts of transparent soils are introduced.Then,several representative applications of transparent soil in underground construction(i.e.,soil deformations induced by the penetration of pile foundations,tunnel excavation-induced movements,and structural responses caused by braced excavations)are presented.Because some research gaps may exist,certain potential research topics are proposed.This review can serve as a guideline for researchers performing experiments using transparent soils.

The primary influence of shear band evolution on the slope bearing capacity

Slope bearing capacity is one of the most important characteristics in slope engineering and is strongly influenced by weak planes,loading conditions,and slope geometry.By presenting the evolution of slip surfaces,this paper explored how the slope bearing capacity is affected by widely observed influencing factors.The initiation and propagation of slip surfaces are presented in laboratory model tests of slope using the transparent soil technique.Shear band evolution under various weak planes,loading conditions,and slope geometries were experimentally presented,and slope bearing capacities were analyzed with the process of shear band evolution.This paper verified that slip surface morphologies have a strong relation with the slope bearing capacity.The same slip surface morphology can have different evolutionary processes.In this case,it is the shear band evolution that determines the slope bearing capacity,not the morphology of the slip surface.The influencing factors such as pre-existing weak planes,loading conditions,and slope geometry strongly affect the slope bearing capacity as these factors govern the process of shear band evolution inside the slope.