Pressure plate testing device capable of controlling suction force by negative pore water pressure

Abstract

The invention discloses a pressure plate testing device capable of controlling the suction force by negative pore water pressure. The pressure plate testing device comprises an unsaturated soil consolidation apparatus, a soil water content change measurement system and a positive and negative pressure conversion system, wherein the soil water content change measurement system consists of a dryer, a water container, a weight sensor and a control system; the positive and negative pressure conversion system consists of a positive pressure control meter, a negative pressure control meter, a pressure converter and an air compressor; a top cover of a pressure chamber is provided with an exhaust hole, so that the pressure chamber is communicated with the atmosphere; and the exhaust hole is sealed by a piece of filter paper which is ventilated and waterproof. For a sample container of the pressure plate testing device, the air pressure in the pressure chamber is equal to the atmosphere pressure, and the suction force value is equal to the absolute value of the pore water pressure, so that the natural state of unsaturated soil can be truly reflected when the suction force is controlled, the suction force state of the natural unsaturated soil is simulated in deed, and the defects of axis-translation technique are overcome; and the pressure plate testing device is simple in structure, convenient to operate and easy to master.

Description

technical field [0001] The invention relates to a civil engineering geotechnical test device, in particular to a device for controlling and measuring unsaturated soil suction, which is applied to the geotechnical test of geotechnical engineering. Background technique [0002] Unsaturated soil abounds in geotechnical engineering, especially in foundation engineering, slope engineering and cavern engineering, mainly natural dry soil and compacted soil, the construction and operation of earth dams, and environmental conditions. Many problems in natural soil slope, slope stability of vertical excavation, ground uplift caused by expansive soil and its collapsible soil are all related to the permeability, strength and deformation characteristics of unsaturated soil, so the research on the properties of unsaturated soil Obviously very necessary. The biggest difference between unsaturated soil and saturated soil is that there are not only solid phase and liquid phase but also gas p...

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Problems solved by technology

At the same time, it is very difficult to use the axial translation technology to measure the load, and it is easy to cause disturbance or distort the measurement results due to the change of the force state of the sample.

For the unsaturated soil triaxial test, artificially increasing the air pressure makes it difficult to prevent the gas in the sample from leaking through the rubber membrane. Bishop once wrapped the rubber membrane with a layer of aluminum foil or filled the pressure chamber with mercury instead of water. But it brings a lot of trouble to the test operation

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