无黏性土颗粒起动临界水力梯度的计算模型

Calculation Model of Critical Hydraulic Gradient for Incipient Motion of Cohesionless Soil Particle

为了得到颗粒起动流失的临界水力梯度,研究基于变截面孔隙管道的几何边界条件,分别对一般存在状态的可动颗粒和临界存在状态的阻塞颗粒进行起动流失的运动力学分析,考虑两种状态下可能影响颗粒起动的不同因素,建立了预测颗粒起动流失临界水力梯度的理论计算模型,并通过已有试验资料验证了模型预测临界水力梯度的有效性。从孔隙管道中颗粒可能存在的实际状态出发,引入相对遮挡度、相对暴露度和应力状态等关键影响因子进行力学分析,探究了渗流方向、相对遮挡度以及相对暴露度等参数对临界水力梯度的影响规律,结果表明建立的计算模型对临界水力梯度预测具有有效性和优越性。

In order to obtain the critical hydraulic gradient for the incipient motion of particles,based on the geometric boundary conditions of the variable cross⁃section porous pipe,the dynamic analysis of the incipient motion of movable particles in the general existence state and the clogged particles in the critical existence state was carried out,respectively,and the different factors that might affect the incipient motion of particles under the two states were considered.A theoretical model for predicting the critical hydraulic gradient of particle incipient motion was established,and the validity of the model for predicting the critical hydraulic gradient was verified by the existing experimental data.The study started from the actual state of the particles in the pore pipe,introduced key influencing factors such as the relative shielding degree,the relative exposure degree and stress state for mechanical analysis,and explored the effect of parameters such as seepage direction,the relative shielding degree,the relative exposure degree on the critical hydraulic gradient.The obtained calculation model is of great significance to the rationality and reliability of the prediction of critical hydraulic gradient.