24 Water Conservancy Coarse grained Soil Vertical Permeation Deformation Instrument

This experiment complies with the DL/T5356-2006 Test Code for Coarse grained Soil in Hydropower and Water Conservancy Engineering. The test method uses infiltration water flow from bottom to top and is suitable for coarse-grained soil. It is used to determine parameters such as permeability coefficient, dry density, porosity, infiltration slope reduction, and infiltration flow velocity of coarse-grained soil.

1、 Technical parameters

1. Test tube specification: ф 300mm * 600mm

2. Test tube height: 600mm

3. Specification of water supply tank: length 250mm, width 200mm, height 200mm

4. Measuring cylinder: 1000mL

5. Measuring cylinder: 100ML

6External dimensions:(Long)*wide*High)160*90*230cm

7. Whole machine weight: 400kg

2、 Usage:

1. Connect the lower water inlet to the water supply pipe, fill the instrument with water, and check the instrument

Are there any blockages or leaks in the various components of the device. After inspection, lower the water supply tank to make the water level in the instrument level with the lower edge of the permeable plate.

2. Remove the top cover, lay a filter on the lower permeable plate, and apply a circle of waterproof material along the contact gap between the cylinder wall and the filter.

3. Open all pressure gauges and place them in the exhaust state.

4. The sample should be filled in 3-5 layers, and the grading of each layer should be the same. Filling layer thickness: Sand soil can be 2cm to 3cm; Gravel soil can have a particle size 1.5 to 2 times larger than the sample size. If necessary, add water equivalent to 1% to 2% of the sample mass, mix evenly before loading.

5. Uniformly layer each weighed sample into a measuring cylinder, compact it with a compaction hammer to the required height, and use vibration densification method for weathered stone slag or crushed soil materials.

6. The sample is saturated using capillary saturation method in the instrument. Adjust the height of the water supply tank so that the water level is slightly higher than the bottom of the sample. Slowly lift the water supply tank, stabilizing for 10 minutes after each 1cm lift. As the water level of the sample rises, connect the corresponding pressure measuring tube and wait until the water overflows the outlet to fully saturate the sample. At this time, the water level of each pressure measuring tube should be level with the water level at the outlet.

7. Based on the fine particle content in the sample, it is preliminarily determined that the failure mode of the sample infiltration deformation is: when it is a pipe surge failure mode, the initial slope of infiltration should be 0.02-0.03, with incremental values of 0.05, 0.10, 0.15, 0.20, 0.30, 0.40, 0.50,

0.70, 1.00, 1.50, and 2.00, gradually increasing from 1.00 to 2.00 thereafter. When approaching the critical slope, the incremental increase in permeability slope should be reduced accordingly; When it is in the form of soil flow failure, the value can be appropriately increased.

8. Gradually increase the water head according to the above regulations. After each increase in water head, the outlet water should be allowed to flow for 30 minutes to 60 minutes. After the water flow stabilizes, the water level of each pressure measuring tube should be measured and the seepage amount should be read using a measuring cylinder. The number of readings for each level of water head should not be less than three times, and the interval between each reading depends on the amount of seepage, preferably 10-20 minutes. At the same time, the temperature of the inlet and outlet water should be measured. When the water level and seepage volume measured three times are basically stable, it can be raised to the next level of water head. Take the average of three readings that are close to each other as the experimental value. For non piping soil, the time can be appropriately extended.