A method for measuring firmness coefficient of structural soft coal

Abstract

The invention discloses a method for determining a tectonic soft coal firmness coefficient. The method comprises the following steps: selecting tectonic soft coal, recording a burial depth of the tectonic soft coal, determining a firmness coefficient f1 according to a national standard coal firmness coefficient determination method (GB / T23561.12-2010), compacting the tectonic soft coal to shaped coal according to different pressures of the burial depth of a coal seam, wherein dwell time is t, then determining uniaxial compressive strength of a briquette coal, calculating a firmness coefficientf2 of the briquette coal, if f1 equals to f2, the dwell time is t0, if f1 does not equal to f2, the dwell time t is increased or decreased, repeating the above steps until f1 equals to f2 so that thedwell time is t0, finally determining the firmness coefficient of a coal body with other burial depth in a same mining area, compacting the tectonic soft coal to the shaped coal, wherein the pressureis obtained by calculating the burial depth, the dwell time is t0, determining the uniaxial compressive strength of the briquette coal, and reckoning the firmness coefficient of the tectonic soft coal according to a relation of the firmness coefficient and the uniaxial compressive strength. The method is simple and convenient, and a measuring result accords with practical situation.

Description

technical field [0001] The invention relates to a method for measuring the firmness coefficient of coal, in particular to a method for measuring the firmness coefficient of structurally soft coal, which belongs to the field of mining engineering. Background technique [0002] In order to study the geological conditions of the coal seam so as to better serve the mining, it is necessary to measure the mechanical parameters of the coal body. At present, my country uses the firmness coefficient (also known as Platts coefficient) f of coal to evaluate the ability of coal to resist external damage. The f value is generally determined by the falling weight method. The drop hammer method believes that the work consumed by the crushing of coal is proportional to the increased surface area of ​​the crushed material, and the constant related to the strength or firmness of the object is related to the crushing ratio. The crushing ratio can be used to express the firmness of the object;...

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Problems solved by technology

[0004] If the drop weight method is used, it is difficult to meet the convenience requirements due to the large number of samples, large amount of repetitive labor, many test steps, long test time, and cumbersome process;

[0005] However, when calculating the firmness coefficient of coal by measuring its uniaxial compressive strength, due to the strain generated by the coal seam under the action of structural stress and formation pressure, the coal body structure will be damaged to varying degrees, and the strength of the coal is low. Soft coal is a kind of loose and broken coal body whose coal body structure suffers from high degree of tectonic stress damage. Its strength is extremely low, and the finished product has obtained the standard sample size (Φ×H=50mm×100mm) stipulated by the International Society of Rock Mechanics. Therefore, it is difficult to directly establish the relationship between the uniaxial compressive strength of structural soft coal and the firmness coefficient of soft coal.

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