Method for determining physical similarity simulation material of solid backfill body

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 σ and strain ε in a loading process, and drawing a ε0-σ0 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 h1=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 σ and strain ε in a loading process, and drawing a ε1-σ1 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 σ and strain ε in a loading process, and drawing a ε2-σ2 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 ε0-σ0 curve 1 and the ε1-σ1 curve 2, and a sum of squared errors between the ε0-σ0 curve 1 and the ε2-σ2 curve 3, and selecting a combined block corresponding to the curve meeting an expression of Σ(εi−ε0)2≤0.5, 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 Σ(εi−ε0)2≤0.5, increasing the number of pieces of the sponge till a curve meeting the expression of Σ(εi−ε0)2≤0.5 is selected out.