Nonsaturated soil hydraulic parameter measuring device and measuring method

Abstract

The invention relates to an unsaturated soil hydraulic parameter measuring device and a measuring method. The device consists of a pressure chamber 12, a pneumatic pump 21, a vacuum pump 8, a loading frame 10, an appliance base 27, hydraulic pressure pipelines 4 and 20, and pneumatic pipelines 11 and 15. The pneumatic pipelines of the pressure chamber 12 are connected with a pneumatic sensor 16, a pneumatic control valve 18 and the pneumatic pump 21; a water filling pipeline 28 of the appliance base 27 is connected with a control valve 29; the hydraulic pressure pipeline 20 in the center of the sample base is connected with a lower clay plate 14, a hydraulic sensor 9, a water volume measuring pipe 17, a hydraulic pressure control valve 19 and the pneumatic pump 21; a hydraulic pipeline 4 in the center of a top hat is connected with the an upper clay plate 14, the hydraulic sensor 9, a water volume measuring pipe 6, a hydraulic pressure control valve 7 and the vacuum pump 8; a sample 30, a top cap 13, a clay plate 14, a sample 30 and a sample base 25 are arranged between two clay plates 14 and are wrapped by rubber membranes; the sample 30, a pneumatic sensor 23, a pneumatic control valve 22 and the pneumatic pump 21 are connected with the pneumatic pipeline 11 which passes through the rubber membrane from the middle of the sample 30; and the pressure of a weight 26 is added to the sample by the loading frame 10 and a pressurizing shaft 3. The device can be used for measuring soil and water retention curve and unsaturated permeability coefficient of various soils under the condition of three-directional loading.

Description

technical field [0001] The invention relates to a geotechnical testing instrument, which belongs to the technical field of civil engineering. Background technique [0002] Unsaturated soil is widely distributed in our country. The natural sedimentary soil widely distributed on the surface of the earth and the soil problems encountered in engineering construction are almost all unsaturated soil problems. Saturated soil in the true sense is rarely seen in engineering practice. This makes the study of unsaturated soil mechanics very realistic and practical. Hydraulic hysteresis is an important feature of unsaturated soil, and hydraulic hysteresis is usually manifested in the hysteresis of the soil-water retention curve, which is affected by many factors, such as soil structure, temperature and especially the stress state. Two important parameters used to describe the hydraulic characteristics of unsaturated soil are the corresponding relationship between unsaturated permeabili...

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Problems solved by technology

At present, there is no instrument at home and abroad to measure the soil-water retention curve and the unsaturated permeability coefficient under the three-dimensional loading state.

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