CN116029142A - Calculation method for water pumping quantity of incomplete well of diving aquifer - Google Patents
Calculation method for water pumping quantity of incomplete well of diving aquifer Download PDFInfo
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- CN116029142A CN116029142A CN202310082379.4A CN202310082379A CN116029142A CN 116029142 A CN116029142 A CN 116029142A CN 202310082379 A CN202310082379 A CN 202310082379A CN 116029142 A CN116029142 A CN 116029142A
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Abstract
The invention discloses a calculation method for the pumping capacity of a non-complete well of a submerged aquifer, which specifically comprises the following steps: the method comprises the steps of (1) performing on-site survey to determine soil layer parameters and hydrogeology conditions of a pumping area, (2) calculating the water level height reached by engineering construction according to foundation pit engineering design, (3) providing incomplete well design parameters and a precipitation scheme, calculating the precipitation depth required by the occurrence field, (4) calculating the pumping quantity of the incomplete well through the incomplete well design parameters, (5) organizing a corresponding pumping scheme to achieve the designed water level reduction depth.
Description
Technical Field
The invention relates to the field of underground engineering construction lowering and drainage in a diving aquifer region, in particular to a calculation method for the pumping quantity of a non-complete well of a diving aquifer.
Background
In the underground engineering construction process, not only the safety of soil unloading to nearby buildings is paid attention to, but also groundwater resources are required to be reasonably extracted so as to reduce the influence on the surrounding environment. Most foundation pit dewatering schemes are formed by combining dewatering wells with waterproof curtains, and in the foundation pit construction process, the foundation pit dewatering schemes are often adopted to reduce the water level inside the foundation pit so as to achieve the aim of implementing dry operation in the foundation pit, and meanwhile, the safety and stability of soil mass around the foundation pit can be improved, and phenomena such as sand flowing and piping are prevented.
At present, the precipitation well is divided into a pressure-bearing water relief well and a diving dredging well, research at home and abroad is mainly focused on the aspect of pressure reduction and precipitation of a pressure-bearing water-bearing layer of a foundation pit, a mathematical model of the pressure-bearing water-bearing layer relief well is built by adding hypothesis conditions, and the damage of sudden gushing of the foundation pit is prevented by pressure reduction and precipitation. However, the submersible dry well encounters more engineering problems in practical engineering, so more assumption conditions are needed to build an effective calculation model, and therefore, the research on the water level change and the water pumping quantity near the submersible well is always a difficult problem in the well flow theory. In the existing calculation method, design constructors calculate the water pumping quantity of the submerged well according to an empirical formula in the specification, but the empirical formula has a certain error and cannot accurately calculate the water pumping quantity of the submerged incomplete well. A part of scholars establish a numerical model through finite element software to simulate the process of the pumping well, and the mode can consider various complex engineering environments, but a great amount of time is required to establish the numerical model, so that the operation difficulty is high and the acquisition is difficult.
Most of the calculation of the water pumping quantity of the submerged incomplete well in the foundation pit engineering is also based on engineering experience, and an accurate calculation result of the submerged incomplete well pumping cannot be obtained, so that the construction requirement of the foundation pit engineering cannot be met when the submerged incomplete well pumping is carried out.
Therefore, how to predict the water extraction of the incomplete well of the diving is an urgent problem, and a novel calculation method for the water extraction of the incomplete well of the diving aquifer needs to be researched and invented.
Disclosure of Invention
Because the problem that the water pumping amount depends on engineering experience in the water pumping process of the submersible complete well is solved, the technical problem of the invention is to provide a calculation method for the water pumping amount of the submersible water-bearing incomplete well according to the hydrogeology of the water pumping well, the design precipitation depth and related engineering standard control standards.
In order to achieve the purpose of the calculation method of the incomplete well water extraction, the technical scheme of the invention is that the calculation method of the incomplete well water extraction for the diving aquifer comprises the following steps:
(1) For a non-complete pumping well of a diving aquifer, performing on-site survey, and determining a water guide coefficient, a water storage coefficient and a soil layer permeability coefficient of the pumping area;
(2) According to the foundation pit engineering design, calculating the water level height reached by engineering construction, and providing incomplete well design parameters including the radius of a pumping well and the pumping well time, and calculating the precipitation depth required by the occurrence field;
(3) The integral function W (u) is calculated by the following formula 0 )：
Wherein u=r 2 /4at，u 0 ＝r w 2 a=t/S ', T is the water conductivity, S' is the water storage, r is the distance from the pumping well, r w Is the radius of the pumping well,t is the pumping well working time;
(4) For calculation of the water extraction of the incomplete well of the submerged aquifer, the water extraction Q increased in the water level falling process is calculated by the following calculation formula:
wherein S is w The water level of the pumping well is lowered to a depth, K is the soil permeability coefficient, and l is the length of the filtering section of the pumping well.
Further, an integral function W (u 0 ) The method is specifically calculated as follows:
further, for the case of multiple submersibles, the permeability coefficient k= Σ (K i h i )/∑h i ，K i Permeability coefficient of the ith aquifer, h i Is the thickness of the ith aqueous layer.
The invention has the main advantages that the traditional standard empirical method calculates the water pumping quantity under the premise of stable flow, the empirical method can not embody the change relation of the calculation result along with time and space, and has larger error, and the state of calculating the incomplete well water pumping quantity can not be dynamically predicted in real time. The calculation method is suitable for calculating unstable flow of the submerged aquifer, and can calculate the water pumping quantity at different times and feed back the water pumping quantity to related projects in time, so that dynamic control of pumping of the foundation pit submerged incomplete well is achieved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a simplified calculation of the pumping of a non-complete well of a submerged aquifer;
FIG. 2 is a cross-sectional view of a foundation pit engineering envelope;
fig. 3 is a diagram showing the comparison between the calculation result of the present embodiment and the on-site monitoring data.
Detailed Description
In order to facilitate an understanding of the computing process of the present invention, the following description will be more fully directed to the selection of related embodiments in conjunction with the associated drawings. The calculation method of the present invention can be applied to different cases and is not limited to the embodiment described herein.
The embodiment of the invention provides a method for calculating the pumping capacity of a non-complete well of a submerged aquifer, which specifically comprises the following steps:
FIG. 1 is a schematic drawing of the calculation of the pumping of a submerged incomplete well according to the present invention, as shown in FIG. 1, the pumping of the incomplete well in the submerged aquifer area causes the water level near the pumping well to drop, and at the same time affects the peripheral water level to drop to different extents, and groundwater near and far from the incomplete well is continuously supplied to the interior of the incomplete well, so that an obvious "funnel" curve of precipitation is formed centering on the incomplete well.
As shown in fig. 1, the non-complete well pumping unsteady flow proposed by the present patent is calculated according to the following principle first according to the underground water dynamics principle. (1) The soil body of the diving aquifer is homogeneous and isotropic, and extends in the horizontal direction infinitely; (2) vertical seepage is ignored; (3) the water head in the submerged well is kept unchanged; (4) The depth of water level reduction caused by incomplete water pumping is smaller, (5) the thickness water flow movement of the submerged aquifer meets the Dupuit assumption; (6) the bottom of the diving water-bearing layer is a watertight medium; (7) The formation heave change is ignored and the overflow situation is not considered. The control equation of the unstable flow constant descent depth of the incomplete well is established by meeting the principle.
Wherein r is the distance from the pumping well, S is the water level reduction depth at any position, T is the water guide coefficient, S' is the water storage coefficient, and T is the pumping well working time.
By adding boundary conditions and solving a control equation by adopting integral transformation, a calculation method of the water level change of the submersible incomplete well about time and space change is obtained, W (u) 0 ) Is an integral function, which is calculated as follows:
where u=r2/4at, u 0 ＝r w 2 T is the water conductivity, S is the water storage, T and S' need to be determined by stepping, and r is the distance from the pumping well, r w The radius of the pumping well is determined when the incomplete well of the submerged aquifer is pumped, and t is the working time of the pumping well.
The calculation of the water pumping quantity of the submerged incomplete well is based on Darcy law and Dupuit assumption, the slope of the water level decrease at the well wall is regarded as the hydraulic gradient at the well wall, the product of the slope and the permeability coefficient of the aquifer is regarded as the flow rate, and the product of the flow rate and the water cross section of the pumping well is the flow rate, so the calculation of the submerged incomplete water pumping quantity can be calculated through the following formula.
Wherein S is w The water level of the pumping well is reduced to a depth, K is the soil permeability coefficient, l is the length of the filtering section of the pumping well, W (u) 0 ) Is an integral function.
The following describes the calculation method according to the present invention in detail with reference to a specific embodiment.
For a non-complete pumping test of a foundation pit of a Nanchang subway, the sectional view of the foundation pit is shown as figure 2, and Nanchang city belongs to subtropical monsoon climate, and has abundant rainfall and abundant water resources. The submerged water level of the subway foundation pit of the flare station is 4m below the ground surface, foundation pit engineering is mainly influenced by a submerged layer, and the submerged layer is mainly positioned on silty clay (3) -1, fine sand (3) -2 and coarse sand (3) -4. The soil layer physical parameters are shown in table 1.
The construction of the pumping well is completed according to the following steps: fixed point, well position hole forming, flower pipe manufacturing, steel pipe installation, gravel filling, water pumping test and the like, and the single well water pumping test of the submerged complete well is carried out by using 1 water pumping hole and 2 observation holes in the survey stage, wherein the parameters of the water pumping test are shown in table 2. The single well water pumping test is divided into 3 stages, and the precipitation depth of the water pumping hole is 1.21m, 2.65m and 3.93m respectively.
TABLE 1 physical and mechanical parameters table for each soil layer
Table 2 parameter table for pumping test
| Name of the name | Parameters (parameters) |
| Type of groundwater | Diving device |
| Radius of pumping well | 0.1m |
| Length of pumping well | 9.5m |
| Pumping time | 8h |
| Distance between |
5m |
| Distance between observation well 2 and pumping well | 10m |
As can be seen from fig. 3, when the water level is reduced from 1.21m to 3.93m, the calculated value of the pumping quantity of the incomplete well is basically consistent with the actual measured value of the pumping test, and the calculated method is relatively consistent with the practical application of the pumping engineering of the submerged incomplete well.
In the design and construction of underground engineering, the invention can accurately calculate the water pumping quantity of the incomplete well water of the submerged aquifer according to the design requirement, and select the type of the water pumping pump matched with the water pumping well, thereby avoiding the situation that the underground water level cannot reach below the bottom of the foundation pit due to too little water pumping quantity of the water pumping well, shortening the construction period of the underground engineering and increasing the safety and stability of the engineering.
The above examples are merely illustrative embodiments of the present invention and the description is more specific and detailed and should not be construed as limiting the scope of the invention. It is to be understood that the present invention is not limited to the specific embodiments described herein, but is capable of modification and variation without departing from the spirit and scope of the invention.
Claims (3)
1. A method for calculating the water extraction of a non-complete well of a submerged aquifer, comprising the steps of:
(1) For a non-complete pumping well of a diving aquifer, performing on-site survey, and determining a water guide coefficient, a water storage coefficient and a soil layer permeability coefficient of the pumping area;
(2) According to the foundation pit engineering design, calculating the water level height reached by engineering construction, and providing incomplete well design parameters including the radius of a pumping well and the pumping well time, and calculating the precipitation depth required by the occurrence field;
(3) The integral function W (u) is calculated by the following formula 0 )：
Wherein u=r 2 /4at，u 0 ＝r w 2 a=t/S ', T is the water conductivity, S' is the water storage, r is the distance from the pumping well, r w Is the radius of the pumping well, and t is the working time of the pumping well;
(4) For calculation of the water extraction of the incomplete well of the submerged aquifer, the water extraction Q increased in the water level falling process is calculated by the following calculation formula:
wherein S is w The water level of the pumping well is lowered to a depth, K is the soil permeability coefficient, and l is the length of the filtering section of the pumping well.
2. A method of calculating the water level and volume for a non-whole well of a submerged aquifer according to claim 1, wherein the integral function W (u 0 ) The method is specifically calculated as follows:
3. a method for calculating the water extraction of a non-complete well for a submerged aquifer according to claim 1, characterized in that the permeability coefficient k= Σ (K i h i )/∑h i ，K i Permeability coefficient of the ith aquifer, h i Is the thickness of the ith aqueous layer.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116341280A (en) * | 2023-05-11 | 2023-06-27 | 中国地质大学（北京） | Method for determining layered permeability coefficient of multiple water-bearing layers with unstable water-resisting layers |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116341280A (en) * | 2023-05-11 | 2023-06-27 | 中国地质大学（北京） | Method for determining layered permeability coefficient of multiple water-bearing layers with unstable water-resisting layers |
| CN116341280B (en) * | 2023-05-11 | 2023-08-18 | 中国地质大学（北京） | Method for determining layered permeability coefficient of multiple water-bearing layers with unstable water-resisting layers |
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