GB/T 23561.3-2009Methods for determining the physical and mechanical properties of coal and rock - Part 3: Methods for determining the block density of coal and rock (English PDF)

3.1 Instruments and equipment

The main instruments and equipment are.

a) oven;

b) drying oven;

c) Wax melting pot;

d) Balance. Sensitivity (minimum division value) 0.01g;

e) Vacuum pumping device, see Figure 1, the vacuum pump is required to be able to reach 0.001MPa (about 7mmHg);

f) Weighing device in water, see Figure 2;

g) Paraffin or polymer resin coating and configuration equipment;

h) Thin thread. silk thread or nylon thread;

i) measuring platform;

j) diamond machines, stone cutters, stone mills and grinders;

k) Vernier caliper. range.200mm, minimum division value 0.02mm.

3.2 Determination and calculation of dry block density

3.2.1

Select a representative approximate cube with a side length of about 4cm to 5cm from the sample as the test piece, the number is not less than three, and the edges are smoothed.

Corners, brush off surface stickies, and remove easy-to-fall debris.

3.2.2

After drying the test piece at 105°C~110°C for 24h, take it out, put it in a desiccator to cool to room temperature, and weigh it to get M.

3.2.3

Tie the test piece with a thin wire, place it in paraffin wax just past the melting point of 60°C for 1s~2s, the thickness of the wax film is about 1mm, check

Check the wax film on the test piece for air bubbles. If bubbles are found, use a small electric iron or hot needle to pierce and flatten the holes, and weigh them on a balance after cooling

Get M1.

3.2.4

Then hang the wax-sealed test piece on the balance hook, see Figure 2, and weigh it in water to obtain M2.

3.2.5

Take out the test piece, wipe off the surface moisture, and re-weigh on the balance. Check whether the quality is different from M1 at this time, if the quality

If the difference exceeds 0.05g, it means that water has been immersed in the test piece, and the measurement should be repeated.

3.2.6

When polymer resin glue is used as the sealing material, see 3.2.1 and 3.2.2 for the preparation of the test piece. In the preparation of polymer resin glue

At the same time, take two parts of polyvinyl chloride resin and eight parts of cyclohexanone according to the mass ratio, first pour the powdery resin into a ground glass bottle, and then put the cyclohexanone

Add hexanone, stir evenly with a glass rod, cover the mouth of the bottle, and wait for the powder to completely dissolve into a transparent glue before use. mix polymer resin

Brush evenly on the surface of the test piece twice, after the solvent volatilizes, a thin film is formed on the surface of the test piece, and then weigh the quality of the sealed test piece M1.then press 3.2.4 and 3.2.5 measured M2.

3.2.7

Determination of paraffin density, see Appendix A.

3.2.8

Calculate the measurement result according to formula (1).

3.3 Determination and calculation of saturated block density

3.3.1

Prepare test pieces according to 3.2.1, and the number of test pieces should not be less than five.

3.3.2

Place the test piece on the plate with holes in the vacuum tank, see Figure 1, and the distance should not be less than 2cm.

3.3.3

Connect the air extraction system, and there should be no air leakage at all connections.

3.3.4

Start the vacuum pump, pump air for 20-30 minutes, then open the three-way piston, and slowly inject water into the vacuum pumping tank until the water surface is high.

2cm ~ 3cm out of the test piece, continue to pump until no bubbles emerge from the surface of the test piece, and the pumping time is not less than 1h. Turn off the vacuum pump, turn

Turn the three-way piston to make the vacuum pumping tank communicate with the atmosphere. The vacuum degree of pumping should be kept at 0.001MPa (about 7mmHg).

3.3.5

Take out the test piece from the vacuum pumping tank, immerse it all in a container filled with water, and let it stand for more than 4h.

3.3.6

Take out the saturated test piece, wipe off the surface moisture with a warm towel, and weigh the saturated test piece Mb.

3.3.7

The following determination steps are carried out according to 3.2.3~3.2.6.

3.3.8

Calculate the measurement result according to formula (2).

3.4 Determination and calculation of natural block density

3.4.1

Prepare the test piece according to 4.2.1.

3.4.2

Store the test piece in the lower part of the desiccator where the water is stored for 1d to 2d. Note that the sample should not be in contact with water so as to keep it in a natural water state.

3.4.3

Take out the test piece and weigh it on the balance to obtain Mz.

3.4.4

The following determination steps are carried out according to 3.2.3~3.2.6.

3.4.5

Calculate the measurement result according to formula (3).

3.5 Determination and calculation of natural block density

3.5.1

Three representative test pieces should be prepared immediately after the rock sample is unsealed (or sampled and measured on the spot).

3.5.2

Immediately weigh the specimen on the balance to obtain Mt.

3.5.3

The following determination steps are carried out according to 3.2.3~3.2.6.

3.5.4

Calculate the measurement result according to formula (4).

4.1 Instruments and equipment

Related instruments and equipment include.

a) Sample processing machinery, including stone cutters, diamond machines, and stone grinders;

b) oven;

c) dryer;

d) Balance. Sensitivity (minimum division value) 0.01g;

e) Dial indicator frame, dial indicator;

f) Caliper. accuracy 0.02mm;

g) Vacuum pumping device, see Figure 1.

4.2 Measurement steps

4.2.1 Preparation of test pieces

three test pieces can be used for the determination of mechanical properties.

4.2.2

Dimensional measurement requirements are as follows.

a) Diameter. measure the three diameters (nine in total) at the two ends and the three sections in the middle which are separated by 120°, and take the arithmetic mean value;

b) Height. measure the five heights at the center and surrounding of the specimen, and take the arithmetic mean;

c) If it is a prism, measure the length and width of the upper, middle and lower sections, and take the arithmetic mean of the six dimensions.

4.2.3

The dimensional error requirements of the test piece are as follows.

a) When measuring all dimensions, the bayonet should be kept vertical or parallel to the surface to be measured, and should not be skewed;

b) The error along the height, diameter or side length of the test piece should not be greater than 0.3mm;

c) The non-parallelism error of both ends of the test piece should not be greater than 0.05mm;

d) The end face is perpendicular to the axis of the test piece, and the maximum deviation should not be greater than 0.25°;

e) The adjacent two sides of the square cylinder or cube test piece should be perpendicular to each other, and the maximum deviation should not be greater than 0.25°.

4.2.4

When measuring the density of dry blocks, dry the test piece at 105°C~110°C for 24 hours, take it out, put it in a desiccator and cool it to room temperature, and weigh it.

Dry weight is M.

4.2.5

When measuring the density of the saturated block, perform saturation treatment on the specimen according to 3.3.2~3.3.6, and weigh the saturated weight to obtain Mb.

4.2.6

When measuring the density of the natural block, the specimen shall be processed according to 3.4.2, and Mz shall be obtained by weighing.

4.3 Calculation of measurement results

According to formula (5), formula (6), formula (7) to calculate the measurement results.