Device and method for measuring hydraulic characteristic parameters of unsaturated soil under increasing/dehumidifying path

Abstract

The invention provides a measuring device of hydraulic characteristic parameters of unsaturated soil in a moisture absorption / desorption path, which comprises a pedestal, a sample container, a semi-permeable membrane, a silk screen, a weighing device, an accommodating bottle, a water inlet pipe, and a water outlet pipe; the sample container is provided with a chamber for accommodating a soil sample to be measured; a cover plate is disposed at the top of the sample container; the chamber of the sample container is tightly fastened with the pedestal; the silk screen is disposed on the pedestal; the semi-permeable membrane is layed on the silk screen; a soil water potential measuring instrument is disposed on the pedestal; a peristaltic pump is disposed at the water inlet pipe; the water inlet pipe and the water outlet pipe pass through the pedestal; one end of each of the water inlet pipe and the water outlet pipe is communicated with the chamber, and the other end of each of the water inlet pipe and the water outlet pipe is communicated with the accommodating bottle; the water inlet pipe is also provided with the peristaltic pump. The device of the invention controls the suction and the moisture absorption / desorption path of the soil sample by dialysis technology, prevents the influence of wetting front, shortens the measuring time, and can measure hydraulic characteristic parameters of unsaturated soil in the moisture absorption path. The invention also provides a measuring method of hydraulic characteristic parameters of unsaturated soil.

Description

technical field [0001] The invention relates to a device and method for measuring hydraulic characteristic parameters of unsaturated soil under a dehumidification / dehumidification path. Background technique [0002] The hazards caused by soil wetting diseases have gradually been paid attention to, such as loess collapsibility, slope destabilization due to wetting, and subgrade wetting deformation. However, the mechanism explanation of the soil wetting process is still immature, which is mainly due to the complexity of the soil wetting process. The soil-water characteristic curve of the soil has hysteresis, that is, the soil-water characteristic curve under the dehumidification path and the humidification path are different. Generally speaking, the soil-water characteristic curve under the humidification path has a relatively small air intake value, and the unsaturated permeability coefficient also has hysteresis under the humidification and dehumidification paths. It can b...

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Problems solved by technology

[0003] The traditional steady-state method to measure the soil-water characteristic curve under the humidification and dehumidification path takes a long time, and the test period ranges from 3 months to 1 year

In recent years, the simple evaporation method based on the transient profile element method has been used to measure the soil-water characteristic curve and unsaturated permeability coefficient of the soil, which shortens the test time, but this method can only measure the hydraulic properties of the soil under the dehumidification path , cannot be used to measure the hydraulic properties of unsaturated soils under a humidification path

Chinese patent application CN201210196089 proposes a method for measuring the permeability coefficient under the humidification path. This method is not suitable for soils with an air intake value greater than 100kPa. In addition, due to the influence of the wetting line caused by humidification, the measurement of the method proposed in this patent is reduced. Accuracy. In this patent, the sensor is used to measure the moisture content of the soil (accuracy is 3%), and there is a large error

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