Unsaturated coarse-grained soil permeameter and test method thereof

Abstract

The invention relates to an unsaturated coarse-grained soil permeameter and a test method thereof. Specifically, the permeameter consists of a sealed chamber, a pressurization system and a measurementsystem. The sealed chamber, the pressurization system and the measurement system are connected through air ducts and water ducts. The sealed chamber is composed of an outer chamber and an inner chamber, ceramic plates are disposed at the upper and lower surfaces of the inner chamber, and small holes are evenly distributed on the side walls of the inner chamber. The pressurization system includesan air compressor, a filter bottle, pressure regulating valves and pressurization pipes. The measurement system includes a measuring platform, a dial gauge, a barometer, measuring tubes and a water tank. Based on the principle of axis translation, the method measures the water absorption and drainage of a coarse-grained soil sample under different suction forces to obtain a soil-water characteristic curve and unsaturated permeability coefficient of the sample. Compared with the prior art, the permeameter provided by the invention can realize measurement of the soil-water characteristic curve and unsaturated permeability coefficient of coarse-grained soil, and the measuring objects can be all sandy soil, and also can be gravel soil, silt and mixed soil.

Description

technical field [0001] The invention belongs to the technical field of geotechnical engineering, and in particular relates to an unsaturated coarse-grained soil permeameter and a method. Background technique [0002] The distribution of unsaturated soil is very wide, and the surface soil closely related to engineering practice is almost all unsaturated soil. The classic principles and concepts of saturated soil mechanics do not fully conform to the actual properties of unsaturated soil, and the use of saturated soil mechanics in engineering design will cause the design to be too conservative or the safety factor to be too low. Therefore, it is the development trend of soil mechanics to study the engineering mechanical properties of soil under the unsaturated state, and it is the need of engineering practice to apply the theory of unsaturated soil mechanics to actual engineering. [0003] Coarse-grained soils are more common in engineering applications, such as embankment an...

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Problems solved by technology

Compared with kaolin, loess and laterite, it is difficult to determine the parameters of unsaturated properties of coarse-grained soil, mainly including: the particle size range of coarse-grained soil is wide, and the inner diameter of the existing unsaturated permeameter is mostly 3.9-10.0cm, which cannot satisfy Experimental requirements; when the clay content of coarse-grained soil is small, its air intake value is small. In order to determine its air intake value, it is necessary for the test instrument to control a small range of suction

Although the soil column method can control the small suction and meet the needs of a large inner diameter, it is more difficult to measure the water in and out

Although adding sensors (such as TDR sensors, pore piezometers and tensiometers or hygrometers) to the soil column method can increase the accuracy of water content measurement, the range of measurable suction is limited by the height of the instrument, and at most does not exceed 10kPa

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