Determination method for permeability coefficient of coarse-grained soil considering side wall effect of permeameter

Abstract

The invention discloses a determination method for permeability coefficient of coarse-grained soil considering a side wall effect of a permeameter. The method comprises the following steps: firstly, through particle screening and particle density tests, measuring the particle size group content, the median particle size and the particle density of a coarse-grained soil sample, and calculating therepresentative particle size d of the sample; respectively obtaining the minimum pore ratio and the maximum pore ratio of the soil body by virtue of maximum and minimum dry density tests of the sample; measuring a permeability coefficient test value k' of the coarse-grained soil sample by adopting an indoor constant head permeability test of a small-size permeameter; then, calculating a plane poreratio correction coefficient xi and the angle alpha of an equal-diameter circular accumulation model under an actual pore ratio e; and finally, according to an expected boundary area rate lambda andan expected boundary pore ratio eb, obtaining a permeability coefficient determination value K which eliminates the influence of the side wall effect. The method is simple and convenient to operate, the permeability coefficient of the coarse-grained soil can be accurately measured by utilizing the indoor geotechnical test parameters of the small-size permeameter, the testing precision is high, andthe error is small.

Description

technical field [0001] The invention relates to a method for measuring the permeability coefficient of coarse-grained soil. Background technique [0002] Geotechnical materials used in civil engineering are a typical porous medium. The pores between the particles in the soil are interconnected to form permeable channels. The flow of water in the pores of soil is called water seepage, and the property of soil that can be passed by water is called soil permeability, which is one of the basic mechanical properties of soil. In 1856, French engineer Darcy found in the vertical seepage test of uniform sandy soil that there is a linear relationship between the seepage velocity v and the hydraulic gradient J, and the ratio K of the two is called the permeability coefficient of the soil, and its value characterizes the soil The strength of permeability is a comprehensive index that reflects factors such as the particle composition, compactness, and seepage pore geometry of soil fil...

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Problems solved by technology

The existing problems are: oversized permeameters often require a large amount of test soil materials, labor and time-consuming, and require high-pressure, high-flow water supply equipment, which is difficult for general indoor laboratories; The material blocks the leakage channel, which increases the complexity of the test operation. It is difficult to control the amount of material smeared. The side wall effect cannot be eliminated if the material is applied too little. If the smear is too thick, the normal pores in the soil will be filled and the sample will be dirty, which will also lead to test errors.

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