Pressure swing controllable gas displacement reaction device and its application in the preparation of air-bearing soil samples

Abstract

The invention belongs to the technical field of manually simulated sample preparation tests for gas-containing sediment in geotechnical engineering, and particularly discloses a variable-pressure controllable gas replacement reaction device and application thereof in preparation of a gas-containing soil sample. The device comprises a reaction vessel and a measuring cylinder which are fixed on the upper surface of the same base, and gas replacement reactions and accurate measurement of gas output under different pressure can be achieved through adjustment of pressure in the reaction vessel and the measuring cylinder; a quantitative relation between mass of gas-absorbable solid particles and replaced gas in different pressure environments under a constant temperature condition can be established; and artificial quantitative control for preparing the gas-containing soil sample is achieved based on the relation. For soil sample preparation, by means of specific crystal structure and high hydrophilicity of zeolite and due to the fact that the specific gravity of the zeolite is close to that of a soil particle, zeolite particles for absorbing saturated methane gas are uniformly mixed with the soil particles, then water is added, the methane gas absorbed in the zeolite particles is replaced by water, so that a bubble-containing soil body is formed, and the prepared gas-containing soil sample is uniform.

Description

technical field [0001] The invention relates to the technical field of artificial simulation sample preparation test of seabed gas-bearing sediments in geotechnical engineering, in particular to a variable-pressure controllable gas replacement reaction device and its application in the preparation of gas-bearing soil samples. Background technique [0002] Submarine shallow gas usually refers to the gas accumulated in the sediment within 1000m below the seabed surface. The components of shallow gas mainly include methane, carbon dioxide, hydrogen sulfide, ethane, etc. Among them, methane generally has the highest content, and is generally distributed in lakes, valleys, bays, deltas and other waters and sea areas with relatively rich oil and gas resources. The gas is mainly derived from the biogenic gas formed by the decomposition of organic matter and the gas produced by deep oil and gas, mantle and magmatic activities and then migrated from the upper part and sealed in the s...

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Problems solved by technology

However, this method is time-consuming and labor-intensive. More importantly, the amount of gas in air-bearing soil cannot be artificially controlled quantitatively, and the samples produced are not uniform, and there is no repeatability between samples. It can only be used for specific model test research, and for General indoor triaxial test cannot be used

There is also a method of preparing unsaturated soil, using air or nitrogen to gradually displace water in saturated soil to prepare air-containing soil samples, but this method can only prepare soil samples with a saturation degree of less than 85% and a continuous gas phase in the soil , but the gas in the actual seabed gas-bearing sedimentary soil exists in the form of free bubbles, and the saturation is generally greater than 85%, so this method cannot effectively realize the artificial simulation preparation of seabed gas-bearing soil samples

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