Method for calculating relative permeability coefficient of unsaturated soil

Abstract

The invention discloses a method for calculating the relative permeability coefficient of unsaturated soil. The method comprises the steps that a certain initial void ratio e0ref is selected as a reference state according a soil sample of a certain type, van Genuchten SWCC equation parameters a1 and b1 are calibrated through an SWCC in the reference state; a parameter zeta is calibrated through an SWCC when the initial void ratio of the soil sample of the type is e0*; based on the calibrated parameters a1, b1 and zeta, the SWCC of the soil sample of the type under the condition of any initial void ratio e0 can be predicted; based on the SWCC under the condition of the initial void ratio e0, corresponding van Genuchten SWCC equation parameters a2 and b2 are obtained through secondary fitting and substituted into a relational expression for calculation, and therefore the relative permeability coefficient kr of the corresponding unsaturated soil can be obtained. By the adoption of the technical scheme, the difficulty in directly measuring the permeability coefficient in an experiment can be effectively overcome, so that consumption of manpower, material resources and time is reduced, meanwhile the workload in practical engineering is reduced to a great extent, and the job schedule is effectively improved.

Description

technical field [0001] The invention relates to the calculation of the relative permeability coefficient of unsaturated soil in civil engineering, water conservancy and environmental engineering, in particular to a calculation method capable of effectively predicting the relative permeability coefficient of unsaturated soil under different initial void ratio conditions. Background technique [0002] Seepage problem is one of the three basic problems in soil mechanics. With the deepening of theoretical research and the development of practical engineering, more and more attention has been paid to the problem of unsaturated soil seepage in geotechnical engineering and environmental geotechnical engineering, such as changes in soil slope saturation and permeability caused by rainfall, and The resulting landslide disaster; the consolidation of compacted soil in the foundation or roadbed and the uplift of expansive soil; the anti-seepage of soil dams; the migration of pollutants ...

AI Technical Summary

Problems solved by technology

However, there are relatively few studies on the evolution law of unsaturated soil permeability coefficient under different void ratio conditions, and the relevant research results are difficult to be directly applied to engineering practice.

[0004] The permeability coefficient is a key parameter in the study of saturated / unsaturated soil seepage. Compared with saturated soil, the experimental determination of the permeability coefficient of unsaturated soil is much more difficult, especially in the case of low saturation, the water in the soil is extremely difficult to drain , so directly testing the unsaturated soil permeability coefficient through laboratory tests will consume a lot of time, manpower and material resources

The difficulty of directly determining the relative permeability coefficient of unsaturated soils by experiments has seriously hindered the solution of this problem

[0005] Therefore, it is necessary to provide a calculation method for the relative permeability coefficient of unsaturated soil to overcome the difficulty of directly measuring the permeability coefficient by conventional experiments

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