Air or Water Inflation Double Packer for Geotechnical Engineering Permeability Testing

brief introduction

Water pressure test is an in-situ test that uses high-pressure method to inject water into the borehole, and calculates the development of rock fractures and permeability based on the water absorption of the rock mass. The water pressure test uses a sealing device to isolate a certain length of drilling test section, and then uses a fixed water head to press water into this section of drilling. The water seeps into the rock body through the cracks around the hole wall, and the final amount of seepage will tend to a stable value. The strength of rock permeability can be determined based on the water pressure head, length of the test section, and stable infiltration water volume. Usually expressed in terms of permeability q, in units of Lu. Definition: When the water pressure is 1MPa and 1L of water is injected per meter of length per minute, it is called 1Lu. In the equation q=Q/(P * L), q is the permeability rate, Lu; Q is the injection flow rate, L/min; P is the total pressure acting on the test section, MPa; L is the length of the test section.

Classification of water pressure tests: simple water pressure test, single point water pressure test, and five point water pressure test.

1. Pre test stage

Slowly increase the water pressure inside the pipeline to the specified test pressure and stabilize it for 30 minutes. If there is a decrease in pressure during this period, water can be injected to supplement the pressure, which should not exceed the test pressure;

Check for water leakage or damage at pipeline interfaces, fittings, etc;

When there is leakage or damage, the pressure test should be stopped in a timely manner, the cause should be identified, and corresponding measures should be taken before retesting.

2. Main experimental stage

Stop water injection and pressurization, stabilize for 15 minutes. After 15 minutes, when the pressure drop does not exceed the allowable pressure drop value, adjust the test pressure to the working pressure and maintain a constant pressure for 30 minutes. Conduct a visual inspection. If there is no water leakage, the water pressure test is qualified. [1]

3、 Main technical parameters:

Sealing hole diameter 30-200mm (can be processed according to user requirements)

Working pressure 1-80MPa (can be processed according to user needs)

The working flow can inject 3-4 tons of grout per hour

Sealing depth of 1-8000m