Large-scale original grade coarse granular soil vertical permeability deformation tester and test method

Abstract

A large-scale original grade coarse granular soil vertical permeability deformation tester is disclosed. A support is provided with a pedestal. The pedestal is successively provided with a transitioncylinder, a first water-permeable plate, a test cylinder, a water collection cylinder and a top plate. A side wall of the test cylinder is provided with voltage testing units at intervals. The voltagetesting units are connected to the test cylinder. The side wall of the water collection cylinder is provided with a drainage pipe used for installing a drainage valve. The drainage pipe is connectedto a measuring cylinder. A lower portion of the pedestal is connected to one end of a water inlet pipe. The water inlet pipe is provided with a water inlet valve. The other end of the water inlet pipeis connected to a pressure tank. The pressure tank is connected to a frequency conversion adjusting pump group. A pipe network pressure sensor is arranged on a pipe between the pressure tank and thefrequency conversion adjusting pump group. The frequency conversion adjusting pump group is connected to a water tank. The pipe network pressure sensor, the frequency conversion adjusting pump group and a PID regulator are electrically connected. The tester and the method are suitable for determining a blasting stone and gravel stone vertical permeability deformation test of coarse-grained soil whose grain diameter is greater than 600 mm.

Description

Technical field [0001] The invention belongs to the technical field of water conservancy and hydropower engineering construction devices and methods, and specifically relates to a large-scale primary-graded coarse-grained soil vertical seepage deformation tester and test method. Background technique [0002] Building earth-rock dams mainly play a water-retaining role in water conservancy and hydropower projects. In the design of earth-rock dams, firstly, in combination with the actual requirements of the project, the dam seepage analysis must be carried out, which can greatly reduce the leakage and damage of the earth-rock dam. In order to study the laws and characteristics of water seepage in the soil structure of the dam filling material, it is necessary to carry out the seepage deformation test of the coarse-grained soil, provide the parameters needed for the calculation of the dam seepage stability analysis and calculation, and select the reasonable anti-seepage arrangement ty...

AI Technical Summary

Problems solved by technology

The permeability coefficient comprehensively reflects the permeability characteristics of the soil, and the seepage slope reflects the anti-seepage ability of the overall structure of the soil. These two technical indicators need to be determined through indoor tests. The maximum particle size of the sample is determined, and the test procedure stipulates that the inner diameter of the instrument should be greater than the sample particle size d 85 When the internal diameter of the conventional test instrument cannot meet the requirements, design and process a large-diameter osmotic deformation instrument, or according to the sample situation, the equivalent elimination method, equivalent substitution method, etc. Similar grading method or mixing method is used to scale down the samples. At present, the size and specifications of the instruments used in laboratory tests are mainly designed for coarse-grained soil (particles less than 60mm), and for the main rockfill filling material of the dam (usually Dmax≤800mm ) permeation test method is not clear, and the applicability of the scale method to the penetration deformation test for oversized particles still needs to be verified by the test. The elimination method and the mixing method will greatly change the fine particle content in the penetration test scale, and the fine Part is just the key factor affecting the determination of the permeability coefficient, so these two processing methods are obviously not suitable for the permeability test; although the similar gradation method keeps the gradation inhomogeneity coefficient unchanged, the scaled gradation after using this method The particle composition is quite different from the original gradation curve, the particles are obviously thinner, and the content of fine particles is much larger than the original gradation content. The permeability coefficient measured by it is obviously reduced, and the difference is an order of magnitude, so this method is unreasonable; In the substitution method, although the measure of replacing the content of the fine particles with an equal amount is adopted to ensure that the fine particle content of the sample remains unchanged, the equal replacement of the fine particles with different particle sizes will affect the change of the content of the remaining parts, which will inevitably affect the determination of permeability. Therefore, there are technical difficulties in how to determine a reasonable substitution particle size and the maximum allowable substitution amount in this method

To sum up, the scale effect has adverse effects on the accurate determination of coarse-grained soil and even coarse-grained soil permeability test results. Therefore, the original gradation sample should be used for the coarse-grained soil permeability test, but the current test regulations do not No specific method for coarse-grained soil permeability test is proposed, and there is no finalized coarse-grained soil vertical seepage deformation instrument

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