Testing apparatus and method for vertical osmotic coefficient of streambed shallow-layer sediment

Abstract

The invention discloses a testing apparatus for a vertical osmotic coefficient of a streambed shallow-layer sediment. The apparatus comprises a thermal insulation sleeve, a metal bar and temperature sensors and pressure sensors positioned in the thermal insulation sleeve and the metal bar. Vertical temperature distribution of a sediment in the vertical sleeve and hydraulic pressure values of two ends of the sediment can be measured under the action of thermal pulse, and the vertical osmotic coefficient of a soil column can be calculated through a relation formula for the osmotic coefficient and spatial and temporal distribution of temperature. The invention further discloses a testing method for the vertical osmotic coefficient of the streambed shallow-layer sediment. According to the invention, the apparatus has a simple structure and high testing efficiency and poses small interference on a spatial structure of particles of a to-be-tested streambed sediment; and the testing method is a novel environment-friendly economic testing method for the vertical osmotic coefficient of a streambed sediment and has good application prospects.

Description

technical field [0001] The invention belongs to the technical fields of water conservancy engineering and agricultural engineering, and in particular relates to a device and method for testing the vertical permeability coefficient of shallow sediments in a river bed. Background technique [0002] In the fields of water resource planning, river hydrology, and river ecology, the permeability parameters of riverbeds are key parameters of various water environment models and total water resources assessment models. The accurate measurement of riverbed permeability, especially the vertical permeability coefficient, is directly related to the accurate calculation of river and groundwater replenishment and discharge, which affects decision makers' reasonable assessment and planning of water resources. For a long time, the classic Darcy infiltration device has been mainly used to measure the permeability coefficient, but because the test process involves the sampling of the river be...

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Problems solved by technology

For a long time, the classic Darcy infiltration device has been mainly used to measure the permeability coefficient, but because the test process involves the sampling of the river bed sediment under the water surface and the serious disturbance of the original soil, it is not suitable for the test of the river bed permeability; Another important indirect test method is to firstly sample and dry the riverbed sediments, and then conduct a particle gradation test, and calculate the permeability coefficient of the riverbed sediments through the characteristic particle size and empirical calculation formulas. However, a large number of literatures show that through The permeability coefficient obtained by this method varies greatly due to the difference in the selection of characteristic particle size and the difference in empirical formulas. Sometimes this difference can reach several orders of magnitude, and its accuracy needs to be further demonstrated.

In addition, like the Darcy penetration test method, the sampling process of this method also disturbs the original sediment structure of the riverbed

[0003] Because the river bed is affected by sediment scouring and silting and benthic biological activities, etc., it usually has high heterogeneity, and it is necessary to obtain a sufficient number of discrete distribution points of the permeability coefficient to better describe the overall permeability of the river bed. Sampling the quality of the lower river bed, and then sending it to the laboratory for penetration testing or sieving testing will bring a greater workload to the test personnel; in addition, with the development and operation of hydropower stations, rivers usually have higher water quality in dry seasons. For deep-water rivers, the sampling of the bed quality or the on-site testing of the permeability are facing greater difficulties

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