METHOD FOR DETERMINING PHYSICAL SIMILARITY SIMULATION MATERIAL OF SOLID BACKFILL BODY

Abstract

A method for determining a physical similarity simulation material of a solid backfill body is provided. A compaction test is run on a gangue backfill body in a lab, to obtain a - curve regarding the gangue backfill body in the compaction process. Backfill blocks are made by using a thin wood board, sponge, and a paper sheet in different proportions, and then an unconfined compression test is separately run on the backfill blocks used for physical similarity simulation, to obtain .sub.i-.sub.i curves regarding the backfill blocks in the compression process. A sum of squared errors (.sub.i.sub.0).sup.2 is introduced to separately calculate a sum of squared errors of the backfill block and that of the gangue backfill body, and accordingly an error between - curves regarding the test block and the gangue backfill body is determined. Finally, a backfill block for which the sum of squared errors is less than 0.5 is determined as a physical similarity simulation material of the gangue backfill body. By fabrication and selection of similar materials, the present invention can reduce an error caused by a selected backfilling material during a physical similarity simulation experiment, guaranteeing the accuracy of the physical similarity simulation experiment for solid backfill mining.

Claims

1. A method for designing a backfill-mining mass ratio in solid backfill mining, comprising the following steps: running a compaction test on a gangue backfill body by using a servo testing machine, recording values of stress and strain in a loading process, and drawing a .sub.0-.sub.0 curve 1 regarding the gangue backfill body in compaction process as a reference curve; setting an excavation height of a physical similarity model to h, and an excavation step to s, to obtain a height of a backfill block h.sub.1=h/n, wherein coefficient n is a real number not less than 1, the height of the backfill block is less than or equal to the excavation height of the model; designing dimensions of the backfill block: setting a length to the excavation step s, a width to a width of the physical similarity model, and a height to the excavation height h of the physical similarity model; selecting two categories of materials as a category-1 combined block and a category-2 combined block of the backfill block, separately cropping the two categories of materials according to the dimensions of the backfill block, separately piling up the two categories of materials till a respective aggregate thickness reaches a designed height of a backfill body, and recording a number K of pieces in each material category when the designed height is reached; running an unconfined compression test: running an unconfined compression test on the category-1 combined block by using the servo testing machine, recording stress and strain in a loading process, and drawing a .sub.1-.sub.1 curve 2 regarding the combined block of sponge and a thin wood board in compression process; and running an unconfined compression test on the category-2 combined block by using the servo testing machine, recording stress and strain in a loading process, and drawing a .sub.2-.sub.2 curve 3 regarding the combined block of sponge, a thin wood board, and a common paper sheet in compression process; and marking twenty equally-spaced points on a coordinate horizontal axis, separately calculating a sum of squared errors between the .sub.0-.sub.0 curve 1 and the .sub.1-.sub.1 curve 2, and a sum of squared errors between the .sub.0-.sub.0 curve 1 and the .sub.2-.sub.2 curve 3, and selecting a combined block corresponding to the curve meeting an expression of (.sub.i.sub.0).sup.20.5, wherein i=1 or 2, as a physical similarity simulation material of a solid backfill body; or if neither of the curves meets the expression of (.sub.i.sub.0).sup.20.5, increasing the number of pieces of the sponge till a curve meeting the expression of (.sub.i.sub.0).sup.20.5 is selected out.

2. The method for designing a backfill-mining mass ratio in solid backfill mining according to claim 1, wherein the two categories of materials are as follows: one category is formed by sponge and a thin wood board, the sponge being fastened on the thin wood board with a transparent tape, to make the aggregate thickness of a backfill block formed by the sponge and the thin wood board equal to h.sub.1; and the other category is formed by sponge, a paper sheet, and a thin wood board, the sponge being fastened on the thin wood board with a transparent tape, to make the aggregate thickness of a backfill block formed by the sponge and the thin wood board equal to h.sub.1/2, and then the cropped paper sheet being fixed on the backfill block formed by the sponge and the thin wood board, to make the aggregate thickness of a backfill block formed by the sponge, the thin wood board, and paper sheet equal to h.sub.1.

3. The method for designing a backfill-mining mass ratio in solid backfill mining according to claim 2, wherein the sponge is ordinary sponge with the thickness of 1.5 cm to 2.5 cm.

4. The method for designing a backfill-mining mass ratio in solid backfill mining according to claim 2, wherein the thickness of the thin wood board is about 2 mm to 4 mm.

5. The method for designing a backfill-mining mass ratio in solid backfill mining according to claim 2, wherein the paper sheet is A4 printing paper.

6. The method for designing a backfill-mining mass ratio in solid backfill mining according to claim 1, wherein the excavation height h of the physical similarity model is not greater than 5 cm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] FIG. 1 is a schematic diagram showing fabrication of a physical similarity simulation material of a solid backfill body according to the present invention; and

[0020] FIG. 2 shows stress-strain curves in a compaction process of solid backfilling materials according to an instance of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS

[0021] Embodiments of the present invention are further described below with reference to the accompanying drawings:

Embodiment 1

[0022] In a method for determining a physical similarity simulation material of a solid backfill body of the present invention, a test block of the physical similarity simulation material is fabricated using different combinations of sponge, a thin wood board, and a common paper sheet, and a compression test is run on the test block and an actual solid backfilling material separately with a servo testing machine. Afterwards, data is processed by making a map, to find out a simulation material that is closest to the actual solid backfilling material.

[0023] a. A compaction test is run on a gangue backfill body (selected from backfill gangue in a coal mine) by using the servo testing machine, stress and strain in a loading process are recorded, and a .sub.0-.sub.0 curve 1 regarding the gangue backfill body in the compaction process is drawn as a reference curve.

[0024] b. According to dimensions of a paved physical similarity model, it is determined that the excavation height of the model is h, and the excavation step thereof is s, to obtain the height of a backfill block h.sub.1=h/n, where n in the equation is a real number not less than 1, that is, the height of the backfill block is less than or equal to the excavation height of the model.

[0025] c. Dimensions of the backfill block are designed as follows: setting the length to the excavation step s, the width to that of the physical similarity model, and the height to the excavation height h of the model. Original materials including sponge, a thin wood board, a common paper sheet, and a transparent tape are acquired. Then, the sponge, thin wood board, and common paper sheet are cropped according to the dimensions of the backfill block.

[0026] d. The sponge is naturally piled up till its cumulative height is greater than the designed height h.sub.1 of the backfill block, and the number K of pieces of the sponge in this case is recorded.

[0027] e. The backfill block is designed to include two categories. One category is formed by the sponge and thin wood board, where a sponge combination is fastened on the thin wood board with the transparent tape, to make the aggregate thickness of a backfill block formed by the sponge and thin wood board equal to h.sub.1. The other one is formed by the sponge, common paper sheet, and thin wood board, where a sponge combination is fastened on the thin wood board with the transparent tape, to make the aggregate thickness of a backfill block formed by the sponge and thin wood board equal to h.sub.1/2, and then the cropped common paper sheet is fixed on the backfill block formed by the sponge and thin wood board, to make the aggregate thickness of a backfill block formed by the sponge, thin wood board, and common paper sheet equal to h.sub.1.

[0028] f. An unconfined compression test is run with the servo testing machine on the backfill block formed by the sponge and thin wood board, stress and strain in a loading process are recorded, and a .sub.1-.sub.1 curve 2 regarding the backfill block formed by the sponge and thin wood board in the compression process is drawn. An unconfined compression test is run with the servo testing machine on the combined block of the sponge, thin wood board, and common paper sheet, stress and strain in a loading process are recorded, and a .sub.2-.sub.2 curve 3 regarding the combined block of the sponge, thin wood board, and common paper sheet in the compression process is drawn.

[0029] g. Twenty equally-spaced points are marked on a coordinate horizontal axis, and a sum of squared errors between the curves 1 and 2 and that between the curves 1 and 3 are calculated separately. After calculation, it is learned that the sum of squared errors between the curves 1 and 2 is less than 0.5. Therefore, a combined block corresponding to the curve 2 is selected as the physical similarity simulation material of the solid backfill body.

Embodiment 2

[0030] A method for determining a physical similarity simulation material of a solid backfill body of the present invention includes the following steps.

[0031] a. A compaction test is run on a gangue backfill body (selected from backfill gangue in a coal mine) by using a servo testing machine, stress and strain in a loading process are recorded, and a .sub.0-.sub.0 curve 1 regarding the gangue backfill body in the compaction process is drawn as a reference curve.

[0032] b. According to dimensions of a paved physical similarity model, it is determined that the excavation height of the model is h, and the excavation step thereof is s, to obtain the height of a backfill block h.sub.1=h/n, where n in the equation is a real number not less than 1, that is, the height of the backfill block is less than or equal to the excavation height of the model.

[0033] c. Dimensions of the backfill block are designed as follows: setting the length to the excavation step s, the width to that of the physical similarity model, and the height to the excavation height h of the model. Original materials including sponge, a thin wood board, a common paper sheet, and a transparent tape are acquired. Then, the sponge, thin wood board, and common paper sheet are cropped according to the dimensions of the backfill block.

[0034] d. The sponge is naturally piled up till its cumulative height is greater than the designed height h.sub.1 of the backfill block, and the number K of pieces of the sponge in this case is recorded.

[0035] e. The backfill block is designed to include two categories. One category is formed by the sponge and thin wood board, where a sponge combination is fastened on the thin wood board with the transparent tape, to make the aggregate thickness of a backfill block formed by the sponge and thin wood board equal to h.sub.1. The other one is formed by the sponge, common paper sheet, and thin wood board, where a sponge combination is fastened on the thin wood board with the transparent tape, to make the aggregate thickness of a combined block of the sponge and thin wood board equal to h.sub.1/2, and then the cropped common paper sheet is fixed on the backfill block formed by the sponge and thin wood board, to make the aggregate thickness of a backfill block formed by the sponge, thin wood board, and common paper sheet equal to h.sub.1.

[0036] f. An unconfined compression test is run with the servo testing machine on the combined block of the sponge and thin wood board, stress and strain in a loading process are recorded, and a .sub.1-.sub.1 curve 2 regarding the combined block of the sponge and thin wood board in the compression process is drawn. An unconfined compression test is run with the servo testing machine on the combined block of the sponge, thin wood board, and common paper sheet, stress and strain in a loading process are recorded, and a .sub.2-.sub.2 curve 3 regarding the combined block of the sponge, thin wood board, and common paper sheet in the compression process is drawn.

[0037] g. Twenty equally-spaced points are marked on a coordinate horizontal axis, a sum of squared errors between the curves 1 and 2 and that between the curves 1 and 3 are calculated separately, and a combined block corresponding to the curve meeting an expression of (.sub.1.sub.0).sup.20.5 is selected as a physical similarity simulation material of a solid backfill body.

[0038] h. If neither of the curves meets the expression of (.sub.1.sub.0).sup.20.5, the number of pieces of the sponge is increased to K+1, K+2, K+3, . . . ; and steps d to g are repeated till a backfill block meeting the expression of (.sub.1.sub.0).sup.20.5 is selected out.

[0039] Among the original materials, the sponge is ordinary sponge with the thickness of about 2 cm; the thickness of the thin wood board is about 3 mm; and the common paper sheet is common A4 printing paper.

[0040] The excavation height of the physical similarity model of the solid backfill body is not greater than 5 cm in general cases.