Outer tube depth drawdown double-tube method for determining hydrogeological parameters of aquitard of outer tube on site

Abstract

The invention discloses an outer tube depth drawdown double-tube method for determining hydrogeological parameters of aquitard of an outer tube on site. The method comprises the following steps: firstly, based on a double-tube test model, deriving the analytical solution of a flow formula of unit horizontal area of aquitard of the outer tube under the condition of reducing the certain constant of a water head on one side of the aquitard column body of the outer tube and keeping the underground water level of the inner tube unchanged; and then giving out experimental information along with time change based on pumping flow, and determining the conduction coefficient, permeation coefficient and water storage rate of the aquitard of the outer tube by adopting a wiring method. According to the double-tube method, the operation is easy, more parameters can be acquired, the precision is high, the key technical problem that the hydrogeological parameters of aquitard on site cannot be determined can be solved, and the testing error in a laboratory after on-site sampling can be overcome; and the outer tube depth drawdown double-tube method has a good popularization and application value.

Description

technical field [0001] The invention relates to an outer pipe drawdown double-pipe method for determining hydrogeological parameters of an aquitard on site, 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 aquit...

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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

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