Hydraulic Properties Of Polypropylene Fiber-modified Aeolian Sand

The natural environment in western China is harsh and the economic level is not high,especially in the desert area.With the deepening of the western development strategy,the importance of highway transportation and infrastructure construction is increasing.Aeolian sand,as a locally enriched material,can be included into the consideration of roadbed filler in the project,while local materials in desert areas can reduce the cost to a certain extent.On the other hand,eolian sand has poor engineering performance.Based on the characteristics of polypropylene fiber and the research status of fiber concrete,polypropylene fiber of different lengths and amounts is mixed into the eolian sand body to conduct research on the hydraulic characteristics of soil.The main research contents and innovative results of this paper are as follows:(1)According to the measured results of the permeability coefficient of aeolian sand analysis found that,different length of polypropylene fiber mixing in the permeability coefficient of the aeolian sand body size has a significant role in reducing,the permeability coefficient decreases with the increase of fiber content,mixed with 12 mm long cutting samples of polypropylene fiber permeability coefficient declines more obvious,and the best dosage of about 0.2%.Through the supplementary test,it is found that the addition of polypropylene fiber increases the dry density of eolian soil,thus increases the density of eolian sand and reduces the effective porosity of soil.(2)In this article,through the independent design test unit,the process of seepage failure of aeolian sand is simulated and the size of the critical hydraulic gradient were determined,and compared with 6mm,12 mm and 18 mm three kinds of fiber length of each sample,whether it is a short cut or cut of polypropylene fiber mixed with long,for the soil critical hydraulic gradient has obvious promotion effect.(3)It is found that polypropylene fiber,as an hydrophobic fiber,forms an hydrophobic film on its surface due to hydrophobicity,which increases the seepage resistance of water flow in the soil and improves the anti-permeability of aeolian sand.At the same time,the fiber forms a spatial network structure in the soil structure,which extends the seepage path and increases the degree of twists and turns.(4)Based on the characteristics of polypropylene fiber and the main influencing factors,the structural formula of critical hydraulic gradient is modified,and the empirical coefficient is determined according to the experimental results and data analysis.By comparing the calculated value with the actual measured value,the empirical formula is applicable to the aeolian sand modified by polypropylene fiber.