Unsaturated soil hydraulic characteristic parameter numerical value inversion method based on evaporation process

Abstract

An unsaturated soil hydraulic characteristic parameter numerical value inversion method based on an evaporation process comprises the following steps: 1) performing an indoor soil body drying test, monitoring the mass change of a soil body, obtaining an actual evaporation capacity process line of the soil body, and recording related environment variable data; 2) selecting a Fredlund model to fit a hydraulic conductivity and soil-water characteristic curve, wherein model parameters are to-be-inverted parameters; 3) establishing a corresponding finite element analysis model according to the characteristics of a soil sample; 4) calculating the surface evaporation capacity of the soil body according to a migration equation of the gas-liquid two-phase flow under the action of a hydrothermal gradient and a Penman-Wilson formula; 5) determining a target function F (X), wherein the F (X) is the error sum of squares of the actually measured evaporation capacity and the calculated evaporation capacity; 6) according to the target function, using a whale optimization algorithm to invert the parameters of the Fredlund model. According to the method, the inversion precision is improved, meanwhile, the obtaining difficulty of actually measured data needed by inversion is reduced, the inversion efficiency is improved, and the method is composed of numerical simulation evaporation process forward modeling analysis and an optimization algorithm.

Description

technical field [0001] The invention belongs to the field of geotechnical engineering calculations, in particular to a numerical inversion method for unsaturated soil hydraulic characteristic parameters based on evaporation process. Background technique [0002] Most of the soil encountered in geotechnical engineering is in an unsaturated state. Unlike saturated soil, unsaturated soil has three phases of solid, liquid and gas, and its properties are more complex. The most important reason for the transformation of saturated soil into unsaturated soil is the change of water content. In the saturated area, the water content of the soil is a constant value, which is generally called the saturated water content; in the unsaturated area, the water content of the soil is not equal to the matrix suction The linear function is generally called the soil moisture characteristic curve. The change of water content directly affects the stability of rock and soil structure, such as uneve...

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Problems solved by technology

[0004] However, most of the current numerical inversion methods for the hydraulic characteristic parameters of unsaturated soil are based on the measured data of the moisture absorption process such as rainfall or water infiltration, and the experimental technology of the moisture absorption process is relatively difficult.

On the other hand, the inversion of unsaturated hydraulic characteristic parameters is a typical nonlinear problem. Traditional inversion methods require a large number of forward calculations. When there are many inversion parameters, convergence difficulties and low efficiency often occur.

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