| Due to Chinese continental monsoon climate,the uneven annual rainfall makes most rivers flooded season in summer.Many river embankments or dams are facing huge threats of piping because of flood peak;The disaster caused by the piping is often seen.In view of the facts that the piping failure has a larger and more extensive hazard,The erosion development and erosion resistance behavior of chemically stabilized dispersive soil were studied in this paper,which supported by the National Natural Science Foundation of China Youth Science Foundation “Phase transition mechanism of granular porous medium with stochastic theory and phase transition seepage deformation coupling model for piping(No.51409029)” and based upon the existing research results of the fund.The main research contents and results are as follows:(1)Hole Erosion Test system : an experimental system for the law of piping erosion under the condition of vertical pressure,the main components of the test system are bracket structure,axially pressure loading system,system of applying constant water level upstream and gathering device.The test system solves the problem that the existing instrument cannot apply the vertical pressure to the specimen,and improves the prefabricated hole forming method and reduces the disturbance to the sample soil during the sample making process.(2)The erosion development rule of soil mixed with three different chemical modifiers is revealed respectively.By using the improved experimental system,the experimental study on piping erosion of dispersed soil has been carried out.The development of Hole Erosion in dispersed soil are explored respectively in the influence of content of admixture,curing time,hydraulic gradient and stress state,etc.Under different influence factors,the cumulative erosion amount and flow rate of specimen treated with three chemical modifiers separately were compared.The influence of different factors on the erosion rate,velocity and the hydraulic gradient at both ends of the sample was analyzed.The erosion development law and the improvement effect under different conditions were summarized.(3)The change rule of soil erosion index under different conditions in Hole Erosion Test is statistically analyzed.The relationship between erosion rate and hydraulic shear force is calculated and analyzed.The results show that the linear fitting degree between erosion rate and hydraulic shear force is relatively high.Through a comprehensive analysis of the erosion index and the critical hydraulic shear force,it is found that the greater the erosion index,the stronger the soil erosion resistance,and the critical hydraulic shear force increases with the increase of incorporation content.The three kinds of modifiers can improve the erosion resistance ability of soil.Under the same condition,the critical hydraulic shear of samples mixed with sodium polyacrylate is always the largest and the maximum erosion rate of samples mixed with sodium polyacrylate is always the smallest.The improvement effect of sodium polyacrylate is the best,and the improvement of Calcium lignosulfonate is the worst.After comprehensive comparison,the effect of resistance to erosion for soil from strong to weak is Sodium polyacrylate,Sodium silicate and Calcium lignosulfonate amendments respectively. |
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