Method for determining compressive peak strength of saturated frozen silty mudstone in deep coal mine

Abstract

The invention provides a method for determining compressive peak strength of a saturated frozen silty mudstone in a deep coal mine. A sampling drill is employed to directly drill a silty mudstone sample in a certain depth aquifer of a deep coal mine, the rock sample is immersed in indoor water to repeatedly test the sample mass until the mass is unchanged to obtain a rock sample in a saturated state; the saturated rock sample is taken and put at a WTD-100 frozen soil pressure testing machine, the freezing temperatures of 10 DEG C, 15 DEG C, 22 DEG C and 25 DEG C are respectively selected, freezing time is 48h, and a uniaxial unconfined compressive strength test is performed in constant loading rates (0.2MPa / s, 0.4MPa / s, 0.6MPa / s and 0.8MPa / s, respectively); according to the actually measured value of the test compressive peak strength of the test, the Origin data analysis software is employed to perform regression analysis for the test data so as to obtain a compressive peak strength prediction experience formula about the natural peak strength, the loading rate and the freezing temperatures. The method can simply and rapidly calculate the compressive peak strength of the saturatedfrozen silty mudstone, and the calculation result of the compressive peak strength is close to the measured data.

Description

technical field [0001] The invention belongs to the field of civil engineering and relates to a method for determining the strength parameters of underground rocks in geotechnical engineering, and in particular relates to a method for determining the compressive peak strength of saturated frozen silty mudstone in a coal mine deep well. Background technique [0002] In the coal mine shaft mining method, although the shaft freezing method is an effective method for crossing loose and unstable alluvial layers or silt, soft rock and other strata, the emergence of water-bearing rock layers during the construction process increases the water inflow in the shaft. Long-term infiltration makes the rock and soil around the water-bearing rock layer in a saturated state. Under the action of low temperature freezing, the strength characteristic parameters of the rock (body) in the saturated state will change. If empirical formulas and theories are used to design the rock (body) freezing o...

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Problems solved by technology

Although the above research involves mechanical properties related to saturated sandy and silty mudstone, the research results of loading rate on the peak strength of saturated silty mudstone in a low temperature environment cannot fully meet the needs of wellbore saturated rock formation freezing design. The process of determining the peak compressive strength through traditional indoor tests is very cumbersome. The relevant domestic regulations only list the compressive strength test procedures of different rocks, but do not involve the impact of loading rate and negative temperature environment on the compressive peak strength.

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