Outer pipe drawdown double-pipe method for determining hydrogeological parameters of aquitard of inner pipe on site

Abstract

The invention discloses an outer pipe drawdown double-pipe method for determining hydrogeological parameters of an aquitard of an inner pipe on site. The method comprises the following steps: firstly, forming, on site, a double-pipe test model for determining the aquitard of the inner pipe, keeping a water head difference between the inner pipe and an outer pipe unchanged, and measuring a change over time of flow of a Mariotte bottle of the inner pipe; deducing a flow formula analytical solution of a unit horizontal area of the aquitard of the inner pipe under conditions that the water head on one side of the outer pipe is reduced by a certain constant and the underground water level of the aquitard of the inner pipe is kept unchanged on the basis of the double-pipe test model; and then providing experimental information of the change over time of the flow of the Mariotte bottle, and determining a transfer coefficient, a permeation coefficient and a water storage rate of the aquitard by adopting a curve fitting method. The outer pipe drawdown double-pipe method is easy to operate, can obtain multiple parameters and is high in precision; the key technical problem that the hydrogeological parameters of the aquitard cannot be determined in situ on site at the present is solved; an error obtained by a test carried out in a lab after on-site sampling is completed is overcome; and the outer pipe drawdown double-pipe method has an extremely high popularization and application value.

Description

technical field [0001] The invention relates to a method for determining the hydrogeological parameters of an aquitard on site, and in particular to a method for determining hydrogeological parameters such as conductivity, permeability coefficient and water storage rate of an aquitard on site. Background technique [0002] With the rapid development of society, the resource and environmental problems of land subsidence caused by the release of water from the aquitard are becoming more and more serious. In the Yangtze River Delta in China alone, the area of ​​land subsidence greater than 200 mm caused by groundwater overexploitation has accounted for one-tenth of the area, and the largest cumulative subsidence has reached 2.80 m, which has caused economic losses of 50 billion U.S. dollars. In addition, groundwater Pollution also spreads from the upper aquifer to the deep. All of these are closely related to the hydrogeological properties of the aquitard, an important compone...

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Problems solved by technology

[0003] Although there have been many studies on the determination methods of hydrogeological parameters of aquifers, most of them are methods of field pumping (or water injection) tests, however, there are few studies on the determination methods of hydrogeological parameters of aquitards adjacent to aquifers , this aspect is because we have always considered the aquitard to be an aquitard or a relatively aquitard, and its contribution rate as a water resource is very small, so little special attention has been paid to it and necessary research has been obtained, and the aquitard is often regarded as Neglected or treated as a boundary; on the other hand, there is also a lack of an effective principle and method that can be used to directly determine these parameters on site

In addition, even if there is experimental research on determining the hydrogeological parameters of the aquitard, it is limited to indoor research. At present, there is no practice of experimental theory and methods for in-situ research on the determination of the hydrogeological parameters of the aquitard. Therefore, this paper The proposal of the invention can fill the blank of the technical method for determining the hydrogeological parameters of the aquitard on site, and has strong application value

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