CLT-1A coarse-grained soil vertical permeability deformation instrument

This experiment complies with the testing regulations for coarse-grained soil in hydropower and water conservancy engineering. The testing method uses permeable water flow from bottom to top and is suitable for coarse-grained soil. It is used to determine the permeability coefficient, critical slope, and failure slope parameters of coarse-grained soil. 1、 Technical parameters: 1. Power supply; 220V 50HZ2 、 Flowmeter; 5V 0.25L-4Lmin1、 Test tube specification: ф 300mm 2, test tube height: 600mm 3, water supply tank specification: ф 510mm, height: 500mm 4, pressure sensor: 10000N5, machine weight: 550Kg 6, user provided equipment: items 3.1.4 and 3.1.5 in the standard, filter screen, compaction instrument 2, usage method: 1. Connect the lower inlet to the water supply pipe to fill the instrument with water, and check whether there are any blockages or leaks in the various components of the instrument. 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. After weighing the sample, in order to reduce the separation of coarse and fine particles and ensure the uniformity of the sample, the sample should be loaded in layers, and the grading of each layer should be the same. It is also possible to add moisture equivalent to 1% -2% of the sample mass, mix evenly, and then proceed with loading the sample. 5. Uniformly layer the weighed sample into the instrument and compact it with a compaction hammer (vibration densification method can be used for weathered stone slag or easily broken soil materials). The total thickness of the sample that meets the required density should be no less than 10cm for sandy soil, no less than 15cm for fine gravel, 20-25cm for medium coarse gravel, and no less than 3-5 times d85 for pebbles, including large particles in the sample. Packing layer thickness: Sand soil is generally 2-3cm; gravel and sand pebbles are 1.5-2.0 times d85. 6. Sampling location. Samples should be taken from different locations with representative strata and seepage flow conditions, such as the bottom of the anti-seepage wall, the internal section of the dam foundation, the water outflow section, and areas with lower anti-seepage strength. 7. At the sampling location. Firstly, dig a soil column with a size larger than the sample size, remove the disturbed soil on the surface of the soil sample, and then carefully and slowly use a soil cutting tool to cut the soil sample to the required size (circular). Lay a layer of sand on the horizontal soil surface surrounding the bottom of the soil column, and make the sand cushion smooth. 9. Put on the cylinder body, with a roughly equal gap between the cylinder body and the surrounding area of the sample. Install a pressure measuring tube in the middle, with a spacing of about 10cm. Then pour expansion fast setting cement mortar (mix ratio: water cement ratio 0.65, ash sand ratio 1:1, mixed with 20% gypsum, 20% calcium chloride, 0.005% aluminum powder) around the sample, and pour it for curing. 10. After the mortar has reached a certain strength (usually 24 hours), carefully cut off the soil column and transport it indoors along with the barrel. Flatten the sample and place a permeable plate and an inclined permeable plate at the lower end of the sample. Connect the upper and lower water inlets and connect them to the water supply pipe. 3、 Sample saturation: 1. After the sample is installed, measure the actual thickness of the sample, and then use the hot water saturation method to saturate it. That is, store hot water in the water supply tank, set the water level slightly higher than the bottom of the sample, and slowly raise the water tank by 1cm each time. Wait for the water level in the water tank to be equal to the water level in the sample, and stop for 10 minutes before raising the water tank again. As the water supply tank rises, let the water seep upward from the bottom of the instrument, slowly saturate the sample, and eliminate the air in the sample. At the same time, as the water level rises, the corresponding pressure measuring tube should be connected. If tap water is used for the experiment, it should be stored for at least one day after aeration before being used as test water to reduce gas segregation in the water. 2. In order to reduce the blockage of sample pores caused by bubbles separated from the test water during the testing process, which affects the accuracy of the test, efforts are made to ensure that the temperature of the test water is equal to or higher than room temperature, or other exhaust measures are adopted. 4、 Test steps: 1. According to engineering requirements, if a load needs to be applied to the top surface of the specimen during the test, a loading device is used to apply the load to the specimen through a piston and an upper permeable plate. 2. During the experiment, when selecting the initial permeability gradient and permeability gradient increment, the failure mode of the sample's permeability deformation should be roughly judged based on the fine particle content. If it is a pipe surge failure, the initial and incremental values of the infiltration slope should be smaller. If it is caused by soil erosion, the initial and incremental values of the infiltration slope should be larger. The principle is to measure both the slope of the specimen before deformation occurs and the critical slope accurately. 3. Raise the water supply tank so that the water level of the water supply tank is higher than the overflow port (inlet) of the infiltration container, maintain a constant water head difference, and form an initial infiltration slope. 4. When adding the first level of water head to the soil in the pipeline, the initial seepage slope can be 0.02-0.03; Then it can generally increase in gradient by 0.05, 0.1, 0.15, 0.2, 0.3, 0.4, 0.5, 0.7, 1.0, 1.5, 2.0, etc. But when approaching the critical slope, the incremental increase in permeability slope should be reduced appropriately. For non piping soil, the initial infiltration slope can be appropriately increased, and the incremental increase in infiltration slope should be appropriately amplified. 5. After raising the water head for 30 minutes to 1 hour each time, measure and record the water level in the pressure measuring tube, and use a measuring cylinder to read the seepage amount three times. The interval between each reading can be appropriately extended. Carefully observe various phenomena that occur during the experiment, such as water turbidity, bubble formation, fine particle jumping, movement or being carried out by water flow, soil suspension, seepage rate, and changes in pressure gauge water level, and describe and record them in the records. 6. If the water level and seepage volume measured four times in a row are basically stable and there are no abnormal phenomena, the water head can be raised to the next level. 7. For each level of infiltration slope, repeat the test according to the provisions of section 5 of this regulation until the test fails. When the water head cannot continue to increase, the experiment can be ended. 5、 After the experiment is completed, clean it up for next use. VI. Calculation and drawing: Conduct the experiment according to specifications 5.0.1-5.0.6.
7、 The test results meet the requirements. 8、 Instrument operation instructions: 1. The main interface is shown in the figure:

Adjust the position of the water head bucket with the "up" and "down" buttons.

The 'Stop' button is used to stop the motor.

The 'Experiment' button is used to measure the total amount of water flow over a certain period of time.

The 'Catalog' button is used for parameter setting and calibration.

Operation setting: used to set the water intake time as shown in the figure

2. System calibration: used to calibrate force values and flow rates as shown in the figure

Just input the actual value based on the actual force and flow rate.

Packing List