Double-tube inner tube method for determining consolidation coefficient and deformation hysteresis index of aquitard in situ

Abstract

The invention discloses a double-tube inner tube method for determining a consolidation coefficient and a deformation hysteresis index of an aquitard in situ. Firstly, a double-tube test model for determining the consolidation coefficient and the deformation hysteresis index of the aquitard by adopting the double-tube inner tube method is formed on site; based on the double-tube test model, a settling volume formula analytic solution of an inner tube aquitard under the conditions that a water head of an outer tube is reduced by a certain constant and an underground water level of one side of a cylinder of the inner tube aquitard is kept unchanged is derived; secondly, according to experimental data that a settling volume of the aquitard in an inner tube is changed along with time, which is measured on the basis of a dial indicator arranged in the inner tube aquitard, the consolidation coefficient and the deformation hysteresis index of the aquitard are determined by adopting a curve fitting method. The double-tube inner tube method disclosed by the invention has the following advantages that the derived analytic solution is strict in theory; in-situ testing on the consolidation coefficient and the deformation hysteresis index of the aquitard is implemented; a testing apparatus and a testing process are simple and easy for operation; a water releasing rate, the consolidation coefficient, the deformation hysteresis index, a conductivity coefficient and a permeability coefficient of the aquitard can be simultaneously obtained, and multiple parameters are acquired.

Description

technical field

[0001] The invention relates to a double-pipe-in-pipe method for determining the consolidation coefficient and deformation hysteresis index of an aquitard in situ, in particular to a method for determining the water release rate, conductivity coefficient and permeability coefficient of an aquitard on site. Background technique

[0002] The water release deformation of the aquifer system is the most direct cause of regional land subsidence. Land subsidence is an environmental geological phenomenon in which the ground elevation slowly decreases. It is an irreparable permanent loss of environment and resources, and it will develop into a geological disaster in severe cases. From the perspective of hydrogeology, deep overburden is the most typical aquifer system. For example, the deep overburden of the Yangtze River Delta in China is an aquifer system consisting of three confined aquifers and four impervious layers, with a thickness of 50-200 m. In the Yangtze ...

Examples

Embodiment

[0098]Make the S(t)~t measured curve in the double-logarithmic coordinate system for the cumulative settlement change with time in Table 1 ( Figure 4 middle dot) and The standard curve (solid line in the figure) is wired so that the two curves overlap (such as Figure 4 ), choose a matching point, and write down the corresponding coordinate value [S]=3.16, and [t]=62, substituting into formula (7), (5), (8) to get

[0099]

[0100] Water release rate:

[0101]

[0102] Consolidation coefficient:

[0103]

[0104] Known average void ratio e=0.861, porosity

[0105]

[0106] Conductivity coefficient:

[0107]

[0108] Permeability coefficient: K=μ s a=6.58×10 -2 ×0.17=1.12×10 -2 (m / d)

[0109] Deformation Hysteresis Index:

[0110] Table 1 Deformation observation data

[0111]

[0112]

technical field

[0001] The invention relates to a double-pipe-in-pipe method for determining the consolidation coefficient and deformation hysteresis index of an aquitard in situ, in particular to a method for determining the water release rate, conductivity coefficient and permeability coefficient of an aquitard on site. Background technique

[0002] The water release deformation of the aquifer system is the most direct cause of regional land subsidence. Land subsidence is an environmental geological phenomenon in which the ground elevation slowly decreases. It is an irreparable permanent loss of environment and resources, and it will develop into a geological disaster in severe cases. From the perspective of hydrogeology, deep overburden is the most typical aquifer system. For example, the deep overburden of the Yangtze River Delta in China is an aquifer system consisting of three confined aquifers and four impervious layers, with a thickness of 50-200 m. In the Yangtze ...

Examples

Embodiment

[0098]Make the S(t)~t measured curve in the double-logarithmic coordinate system for the cumulative settlement change with time in Table 1 ( Figure 4 middle dot) and The standard curve (solid line in the figure) is wired so that the two curves overlap (such as Figure 4 ), choose a matching point, and write down the corresponding coordinate value [S]=3.16, and [t]=62, substituting into formula (7), (5), (8) to get

[0099]

[0100] Water release rate:

[0101]

[0102] Consolidation coefficient:

[0103]

[0104] Known average void ratio e=0.861, porosity

[0105]

[0106] Conductivity coefficient:

[0107]

[0108] Permeability coefficient: K=μ s a=6.58×10 -2 ×0.17=1.12×10 -2 (m / d)

[0109] Deformation Hysteresis Index:

[0110] Table 1 Deformation observation data

[0111]

[0112]

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