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土石混合体是由块石、砾石与砂土、黏土等固体颗粒组成,以块石镶嵌在细粒土体中为结构特征的松散介质。由于其颗粒松散特性,细颗粒在渗流作用下易于流失而形成渗流侵蚀。采用室内试验与数值模拟相结合的方法,扩展渗流侵蚀模型在土石混合体渗透侵蚀研究中的应用。选取云南某滑坡土石混合体为研究对象,采用自制的渗透侵蚀装置,模拟土体基质渗透侵蚀过程,获取土体基质侵蚀参数试验值。根据块石在土体基质中分布特征,建立不同块石含量特征的土石混合体计算模型。基于参数试验值及渗流侵蚀方程、耦合渗流控制方程及孔隙率控制方程,模拟土石混合体渗流侵蚀过程,分析块石含量对土石混合体渗透侵蚀特性的影响。模拟结果表明:在同等水力梯度及时间条件下,块石含量与土石混合体宏观平均流速初值、侵蚀颗粒密度值呈反比,与液化颗粒密度峰值呈正比;块石含量与渗流侵蚀方程中试验参数存在线性相关性。将块石含量作为土石混合体结构特征引入渗流侵蚀方程中,以构建适用于土石混合体的渗流侵蚀模型。
Earth-rock mixture is composed of solid rock, gravel and sand, clay and other solid particles to block inlaid in the fine-grained soil as a structural feature of loose media. Due to the loose nature of the particles, fine particles are easily lost by percolation to form seepage erosion. The combination of laboratory test and numerical simulation is used to extend the application of seepage erosion model in the study of infiltration erosion of soil-rock mixture. A soil-rock mixture in a landslide in Yunnan Province was chosen as the research object. A homemade infiltration erosion device was used to simulate the infiltration process of the soil matrix. The test values of soil matrix erosion parameters were obtained. According to the distribution characteristics of rock mass in soil matrix, a calculation model of rock-soil mixture with different rock mass contents was established. Based on the parameter test value, seepage erosion equation, coupled seepage control equation and porosity control equation, the seepage erosion process of soil-rock mixture was simulated, and the influence of rock mass content on the erosion behavior of soil-rock mixture was analyzed. The simulation results show that under the same hydraulic gradient and time, the content of rock mass is inversely proportional to the initial value of macroscopic mean flow rate of rock-soil mixture and the density of erosion particles, and is proportional to the peak value of liquefaction particle density. The parameters are linearly related. The rock mass content is introduced into the seepage erosion equation as the structural feature of soil-rock mixture to construct the seepage erosion model suitable for the mixture of rock and soil.