Abstract
The critical hydraulic gradient of cohesive soil is an important condition for judging soil piping. For force analysis of movable particles in pore channels of soil, this study proposes to consider the influence of surrounding particles on the drag force of movable particles by water flow. According to the principle of relative motion, considering the interaction force between moving objects in still water, the value of the drag force of water flow that is affected by surrounding particles is calculated, to derive the method of the critical hydraulic gradient. This calculation method is suitable for the results of previous piping tests, and the method is accurate and concise.
Highlights
Advances in Civil Engineering piping is considered to derive the critical hydraulic gradient of noncohesive soil piping
Noncohesive piping soil consists of the following two types of soil particles: framework particles and movable particles. e pore size of soil can be described by two capillary models that have different cross-sectional sizes [9], and the movement of movable particles in pores can be approximated as the movement of particles in a circular pipe fluid. e minimum diameter (d0) and maximum diameter (d2) of a pore channel are, respectively [9,10,11]: 1 8n d0 β 3(1 − n)Dh, (1)
According to the scientific literature [14], when two balls move in still water, the formula for calculating the resistance that acts on one of the balls is given by the relative motion
Summary
Noncohesive piping soil consists of the following two types of soil particles: framework particles and movable particles. e pore size of soil can be described by two capillary models that have different cross-sectional sizes [9], and the movement of movable particles in pores can be approximated as the movement of particles in a circular pipe fluid. e minimum diameter (d0) and maximum diameter (d2) of a pore channel are, respectively [9,10,11]:. E pore size of soil can be described by two capillary models that have different cross-sectional sizes [9], and the movement of movable particles in pores can be approximated as the movement of particles in a circular pipe fluid. Assuming that soil particles have the same shape, the effective diameter of soil particles can be obtained by the following formula [12, 13]: Dh. where ΔSi is the mass percentage of the ith particle group in the soil particles and Di is the representative particle size of the ith particle group in the soil particles. It is assumed that when the particle size is less than or equal to the smallest diameter (d0) of the pore channel, the soil is potentially unstable. V cwd20J, μw 32 twhere cw is the weight of water, μw is the viscosity of water, d0 is the smallest diameter of the pore channel of soil particles, and. J is the hydraulic gradient at both ends of the channel
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