Method for calculating specific heat at clay freezing stage by performing energy substitution on phase-change latent heat of water in soil

Abstract

The invention provides a method for calculating specific heat at a clay freezing stage by performing energy substitution on phase-change latent heat of water in soil. The method comprises steps as follows: specific heat of soil mass is obtained through superposition of weighted average of specific heat of solid components of soil in the soil mass and specific heat of water in soil and phase-change latent heat of water in soil; content of components in the soil mass in the phase-change temperature range is determined according to the indoor soil test, and specific heat, without consideration of the phase-change latent heat, of the soil mass is obtained; the phase-change temperature range is divided into a plurality of sections, the phase-change latent heat is distributed in the phase-change temperature range according to the content of unfrozen water in each section, absorbing and releasing heat in each temperature interval section during temperature changing is obtained, and a curve of the specific heat changing with the temperature in the phase-change temperature range is obtained; the specific heat of soil samples at corresponding temperature points is measured by a calorimeter instrument. The method has the benefits as follows: the blank of the relation of specific heat changing with the temperature in the phase-change process of the water in soil is filled up, and a specific heat-temperature function adopting the temperature as an independent variable and considering the phase-change latent heat in the clay freezing phase change process is established. The calculation result is accurate and reliable, and the method is simple and feasible.

Description

technical field [0001] The invention belongs to the field of rock-soil freezing research in the subject of civil engineering, and in particular relates to a specific heat calculation method of clay freezing stage in which latent heat of water phase change in soil is replaced by energy, which is mainly applied to the specific heat calculation of natural frozen soil and artificial frozen soil. Background technique [0002] With the continuous development of social economy, the continuous growth of population and the relative reduction of space, the development of underground space has become an important means and development trend for human beings to expand their living space. "The 21st century is the century of human development and utilization of underground space" ("Tokyo Declaration"), underground engineering has become a very active field of geotechnical engineering. Under the situation that underground engineering construction is developing towards deeper and more diffi...

AI Technical Summary

Problems solved by technology

[0008] When analyzing the freezing temperature field to calculate the specific heat, there are mainly the following problems: (1) The specific heat is assumed to be constant in the calculation of the freezing stage; (3) Although the temperature change is considered, the specific heat of the clay before and after freezing is calculated separately, without considering the influence of the phase change on it, and ignoring the release of latent heat during the phase change of the water in the soil

[0009] First, the fact that the specific heat of soil changes during the freezing stage is beyond doubt; second, temperature is an important factor in the change of specific heat; finally, during the freezing stage, a large amount of heat is released during the phase transition of water in the soil , will inevitably lead to changes in the specific heat value. If the change in specific heat is ignored, it will inevitably cause a gap between the calculated freezing capacity and the actual cooling capacity, resulting in waste of resources.

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