Device and method for testing garbage double-porosity seepage parameters

Abstract

The invention discloses a device and a method for testing garbage double-porosity seepage parameters, and the method is characterized in that the integral seepage parameters of garbage are obtained through a constant water head seepage test in a saturated state, and the seepage parameters of large and small pore areas are tested in stages by skillfully utilizing the difference of the water holding capacities of the large and small pore areas; the seepage parameters of the large-pore area of the garbage are obtained through a free drainage test under gravity, and the seepage parameters of the small-pore area of the garbage are obtained through a graded drainage test under different air pressures. The testing device comprises a filling structure, a uniform water distribution structure, an adjustable water and gas supply structure and a measuring structure, values of 13 seepage parameters in a double-porosity model are directly determined in a physical testing mode, and only an interface exchange coefficient ka of a large-pore area and a small-pore area is obtained through numerical inversion. The number of seepage parameters needing numerical simulation is reduced, and the feasibility and actual use value of the double-porosity model for seepage analysis of the refuse landfill are remarkably improved.

Description

technical field [0001] The invention relates to the field of measurement, in particular to a device and method for testing double-porosity seepage parameters of garbage. Background technique [0002] There are more than 28,000 domestic waste landfills in and around cities in my country, with a stock of more than 6 billion tons of waste. The biochemical degradation of garbage produces a large amount of leachate and landfill gas, which can easily induce environmental disasters such as landfill landslides, groundwater soil and air pollution. The source of these disasters is closely related to the migration process of liquid gas in the garbage pores. The water vapor seepage characteristic of garbage is the basis for improving the disaster prevention and control level of landfill. [0003] Landfill seepage is defined as the flow of water (ie, leachate) and gas (landfill gas) through the pores of landfill. Different from the general homogeneous rock and soil mass, domestic waste...

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Problems solved by technology

This is also the most common method currently used by scholars to obtain dual-porosity seepage parameters, such as Ke et al. (Analytical solution of leachate flow to vertical wells institutional solid waste landfills using a dual-porosity model. 40.) and Liu et al. (Modeling the oxygen transport process underpreferential flow effect in landfill. [J] Environmental Science and Pollution Research, 2018, 25, 18559-18569.) Shaft precipitation and gas injection tests cannot distinguish between large pores and small pores The seepage process in the pore area leads to the test data according to the single pore model (that is, the garbage dump is regarded as a whole) during the test process. After the test is completed, the test results are split into a double-porosity model by means of numerical simulation. , the seepage parameters in the large pore area and the seepage parameters in the small pore area are respectively obtained

For example, Ke et al. determined three key parameters through numerical simulation of shaft pumping tests: the volume ratio of the large pore area w f , Saturated permeability coefficient k in large pore area swf , saturated permeability coefficient k in the small pore area swm , and the remaining model parameters are simply assumed or used for reference. This numerical simulation method is difficult to guarantee the authenticity and accuracy of the seepage parameter values, and also significantly reduces the reliability of the dual-porosity seepage model.

[0005] Compared with numerical simulation, physical test has better uniqueness and reliability, but there is no test device and method to directly determine the seepage parameters in the dual porosity model through physical test

The physical tests reported in the current literature cannot distinguish the seepage process in the large-pore and small-pore regions. Seepage parameters in small pore area

It is difficult to obtain the value of the dual-porosity seepage parameters of waste through physical testing in the existing technology, which greatly limits the feasibility and practical value of the dual-porosity model for landfill seepage analysis

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