Groundwater pipe well pumping simulation device and test method for centrifugal model test

Abstract

The present invention belongs to the field of underground space development, and is a groundwater pipe well pumping simulation device and test method for centrifugal model tests. The technical scheme is as follows: the pumping simulation device is arranged on the hanging bucket of a centrifuge; the groundwater pipe well pumping simulation device comprises a main model box for filling simulated soil and simulated groundwater, a secondary model box for filling simulated groundwater, a water storage tank and a pumping system; the secondary model box is located on the side of the main model box, and is connected to the main model box through a connecting pipe at the bottom; the water storage tank is installed above the secondary model box, and a one-way exhaust valve is installed on the top; an air inlet pipe and a water outlet pipe are installed at the bottom of the water storage tank, and the air inlet pipe and the water outlet pipe extend downward into the secondary model box; the pumping system is controlled by a variable frequency water pump, and comprises a pipe well and a water guide pipe; the pipe well extends into the main model box; one end of the water guide pipe is connected to the pipe well, and the other end extends into the water storage tank. The simulation of groundwater pipe well pumping in the centrifugal model test is realized.

Description

Technical Field

[0001] The invention belongs to the field of underground space development, and in particular relates to an underground water pipe well pumping simulation device and a test method for a centrifugal model test. Background Art

[0002] With the increasing scarcity of urban land resources, underground space development has become an important means to solve urban land use, population, transportation, environment and other problems and optimize urban space structure. With the increasing saturation of shallow underground space development at this stage, the development of deep and large underground space has also become an inevitable trend in the utilization of underground space resources, which has brought about a large number of deep foundation pit projects. Most of the hot spots for underground space development and construction are located along the river and the coast. These areas have deep aquifers, abundant water, high head pressure and strong permeability, which have a significant impact on the safety of underground projects. The deep groundwater control problem faced by foundation pit projects has become particularly prominent. Pipe well pumping is a common technical measure to achieve safe excavation of foundation pits. However, with the development of urban construction, the surrounding areas of new buildings are often densely populated with numerous pipelines and crisscrossed subway tunnels. The environmental conditions are becoming increasingly complex and sensitive. The construction period of deep and large foundation pit projects is long. Long-term and large-scale pumping of deep groundwater will cause large-scale subsidence of the surrounding ground, affecting the environmental safety of surrounding buildings (structures). Improper handling will cause major economic losses and social conflicts. The premise of a reasonable assessment of the impact of groundwater pumping on the surrounding environment is to have a clear understanding of the hydrogeological parameters and the laws of pumping influence. At present, it is mainly carried out through field tests, parameter fitting, and estimated simulation. However, due to the limited and scattered data obtained from field tests, the boundaries are difficult to control, and the fitting of hydrogeological parameters is still highly empirical, there is still a large difference between the estimated results and the project implementation. Indoor model tests can more accurately control boundary conditions and material properties, have a lower cost than field tests, and can more conveniently arrange sensors as needed to obtain more abundant data. Since the deadweight has an important influence on pumping and the stress deformation of the soil, and the biggest advantage of geotechnical centrifuge model test technology is that it can make the stress of the model and the prototype equal, the deformation similar, and the failure mechanism the same, the geotechnical centrifuge model test technology has become a powerful tool in the current field of geotechnical model test research. The geotechnical centrifuge model test is carried out in an overweight, closed, and narrow space. Under this condition, it is a complex process to realize the foundation pit pumping process, boundary head simulation, and data collection. At present, there is no mature test equipment and related technical achievements, and it is impossible to simulate the pipe well pumping process in the centrifuge model test. Summary of the invention

[0003] In order to solve the above problems, the present invention provides a groundwater pipe well pumping simulation device and test method for centrifugal model test, which realizes the simulation of groundwater pipe well pumping in the centrifugal model test.

[0004] The technical scheme of the present invention is as follows: an underground water pipe well pumping simulation device is arranged on the hanging bucket of a centrifuge; the underground water pipe well pumping simulation device comprises a main model box for filling simulated soil and simulated groundwater, a sub-model box for filling simulated groundwater, a water storage tank and a pumping system; the sub-model box is located on the side of the main model box and is connected with the main model box through a connecting pipe at the bottom; the water storage tank is installed above the sub-model box, and a one-way exhaust valve is installed on the top; an air inlet pipe and a water outlet pipe are installed at a hole at the bottom of the water storage tank, and the air inlet pipe and the water outlet pipe extend downward into the sub-model box; the pumping system is controlled by a variable frequency water pump, and comprises a pipe well and a water guide pipe; the pipe well extends into the main model box; a hole section is provided below the pipe well, and filter material is filled inside; one end of the water guide pipe is connected to the pipe well, and the other end extends into the water storage tank; a one-way valve is installed on the water guide pipe; and visual observation windows are provided on the sides of the main model box, the sub-model box and the water storage tank.

[0005] Based on the above technical features: a valve is provided on the connecting pipe.

[0006] Based on the above technical features: there are two auxiliary model boxes, which are symmetrically arranged on both sides of the main model box.

[0007] Based on the above technical features: there are multiple pumping systems, and the variable frequency water pumps of each pumping system are independently controlled.

[0008] Based on the above technical features: a first anti-filter device is arranged at the connecting pipe located at the main model box; a second anti-filter device is arranged at the air inlet pipe and the water outlet pipe located at the water storage tank.

[0009] Based on the above technical features: the control line of the variable frequency water pump is connected to the slip ring of the centrifuge and then connected to the control room outside the centrifugal field.

[0010] Based on the above technical features: a test method for a groundwater pipe well pumping simulation device for centrifugal model test is:

[0011] Step 1: Before the test begins, fill the main model box with simulated soil under 1g conditions; inject dyed simulated groundwater into the main model box and the auxiliary model box to the static water level; adjust the height of the air inlet pipe to the static water level, and insert the outlet pipe into the lower part of the auxiliary model box; open the one-way exhaust valve; open the one-way valve. The one-way exhaust valve and the one-way valve should always be in the open state during the test.

[0012] Step 2: After the test starts, turn on the centrifuge and accelerate to the test designed centrifugal acceleration, start the variable frequency water pump, and control the dynamic water level by adjusting the power of the variable frequency water pump. The water pumped from the pipe well enters the water storage tank through the water pipe for temporary storage. At this time, the water level in the main model box becomes the dynamic water level; the image acquisition equipment in the matching centrifuge field collects the dynamic water level and soil deformation process through the visual observation window.

[0013] The beneficial effects are as follows: (1) The device has a simple principle and can simulate single-well or multi-well pumping as needed; (2) It is easy to control. The control line of the variable frequency water pump can be connected to the slip ring of the centrifuge, and then connected to the control room through the slip ring of the centrifuge, so as to realize independent control of the pumping flow of each pumping well outside the centrifuge; (3) Data acquisition is convenient. Combined with the image acquisition equipment, it can dynamically and comprehensively collect water level changes and soil deformation data; (4) It has a wide range of applicability and can be used for pipe well pumping simulation under various soils and soil simulation materials; (5) It can realize stable water level control in the centrifuge; (6) It can realize internal water circulation in the centrifuge without drainage or water replenishment. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a front view of the device of the present invention.

[0015] Figure 2 It is a top view of the device of the present invention.

[0016] The numbers in the figure are indicated as follows: main model box 1; auxiliary model box 2; water storage tank 3; pumping system 4; first organic glass window 5; second organic glass window 6; side wall 7; connecting pipe 8; valve 9; first filter device 10; third organic glass window 11; one-way exhaust valve 12; air inlet pipe 13; water outlet pipe 14; second filter device 15; pipe well 16; variable frequency water pump 17; water guide pipe 18; perforated section 19; filter material 20; control line 22; one-way valve 23; simulated soil 24; static water level 25; dynamic water level 26. DETAILED DESCRIPTION

[0017] The specific embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings. These embodiments are only used to illustrate the present invention, but not to limit the present invention.

[0018] In the description of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0019] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0020] Furthermore, in the description of the present invention, unless otherwise specified, “plurality” means two or more.

[0021] like Figure 1 and Figure 2 As shown, a groundwater well pumping simulation device for centrifugal model test includes a main model box 1 and auxiliary model boxes 2 arranged on both sides of the main model box 1, water storage tanks 3 are installed above the auxiliary model boxes 2, and a pumping system 4 is installed inside and above the main model box 1. The auxiliary model box 2 can be one or more. Figure 1 and Figure 2 The figure is only an example of this embodiment. The function of the main model box 1 is to simulate the water level change and soil deformation during the pipe well pumping process. The functions of the auxiliary model box 2 and the water storage tank 3 are to control the boundary water level, water buffer and water circulation in the centrifugal field in the main model box 1. The boundary water level refers to the water level of the simulated soil 24 at the side wall 7 of the main model box 1.

[0022] There is a visual observation window on one side of the main model box 1. Figure 1 The first organic glass window 5 is shown, and the other sides are made of aluminum alloy, with an open top. One side of the auxiliary model box 2 is provided with a visual observation window, such as Figure 1 The second organic glass window 6 is shown, and the other sides are made of aluminum alloy, and the top can be opened. The main model box 1 and the auxiliary model box 2 are integrated, share a side wall 7, and are connected by a number of connecting pipes 8 arranged at intervals at the bottom. The connecting pipe 8 has a valve 9. The connecting pipe 8 leads to the main model box 1. A first anti-filter device 10 is provided on one side. The function of the first anti-filter device 10 is to prevent the simulated soil 24 from entering the auxiliary model box 2.

[0023] The water tank 3 is installed above the auxiliary model box 2, and one side of the water tank 3 is a visual observation window. Figure 1The third organic glass window 11 shown is made of aluminum alloy on the other five sides, and a one-way exhaust valve 12 is installed on the top. The bottom of the water tank 3 is opened to install an air inlet pipe 13 and an outlet pipe 14. The air inlet pipe 13 and the outlet pipe 14 are located at the water tank 3 and a second anti-filter device 15 is set. The function of the second anti-filter device 15 is to prevent the pumping system 4 from bringing in simulated soil 24 and entering the auxiliary model box 2 after passing through the water tank 3. The air inlet pipe 13 and the outlet pipe 14 are respectively inserted into the auxiliary model box 2. The height of the air inlet pipe 13 can be determined according to the design value of the static water level 25, and the pipe mouth is at the same height as the static water level 25. A one-way exhaust valve 12 is installed on the top of the water tank 3. The exhaust direction of the one-way exhaust valve 12 is to exhaust from the water tank 3 to the outside. When the variable frequency water pump 17 extracts the simulated groundwater from the main model box 1 and discharges it into the closed water tank 3 through the water guide pipe 18, it can exhaust to the outside, so that water can enter.

[0024] The pumping system 4 includes a pipe well 16, a variable frequency water pump 17, and a water pipe 18. The pipe well 16 is inserted into the main model box 1. Below the pipe well 16 is an opening section 19, which is filled with filter material 20. The control line 22 of the variable frequency water pump 17 is connected to the slip ring of the centrifuge, and a one-way valve 23 is installed on the water pipe 18. One end of the water pipe 18 is connected to the pipe well 16, and the other end is inserted into the water tank 3. The one-way valve 23 controls the flow of water from the main model box 1 to the water tank 3 to prevent the water from flowing back to the main model box 1 after the variable frequency water pump 17 is turned off, which affects the test. The function of the filter material 20 is to prevent the simulated soil 24 from being pumped into the pumping system 4.

[0025] The working principle of the present invention is: first, fill the simulated soil 24 in the main model box 1 under 1g conditions, and inject the dyed simulated groundwater into the main model box 1 and the auxiliary model box 2 to the static water level 25, install the pumping system 4 and the water storage tank 3 according to the test design, and connect the control line 22 of the variable frequency water pump 17 to the control room outside the centrifugal field through the centrifuge slip ring. After the test starts, turn on the centrifuge to accelerate to the test design centrifugal acceleration, start the variable frequency water pump 17 in the control room, and control the dynamic water level by adjusting the power of the variable frequency water pump 17. The water pumped out by the pumping system 4 enters the water storage tank 3 through the water pipe 18 for temporary storage. Due to the presence of the one-way exhaust valve 12, the water inlet of the water storage tank 3 can be realized. At this time, the water level in the main model box 1 becomes the dynamic water level 26, and the water level and soil deformation process can be collected by the image acquisition device in the matching centrifugal field. When the water level in the auxiliary model box 2 is lower than the static water level 25, the outlet of the air inlet pipe 13 is exposed to the air to take in air, and the outlet pipe 14 drains water from the water storage tank 3 to the auxiliary model box 2 until the static water level 25, the outlet of the air inlet pipe 13 is blocked by water, and the outlet pipe 14 stops discharging water. The main model box 1 and the auxiliary model box 2 directly form a communicating vessel through the connecting pipe 8 arranged at intervals at the bottom, so that the boundary water level of the main model box 1 is also maintained at the static water level 25; that is, the water level of the simulated soil at the side wall 7 is maintained at the static water level 25. The first anti-filter device 10 arranged on one side of the main model box 1 of the connecting pipe 8 prevents the simulated soil 24 in the main model box 1 from entering the auxiliary model box 2, and the second anti-filter device 15 in the water storage tank 3 prevents the simulated soil 24 pumped out by the pumping system 4 from entering the auxiliary model box 2. The variable frequency water pumps 17 of each precipitation simulation device are independently controlled, and the flow rate of each simulated precipitation well can be conveniently controlled as needed. By closing the valve 9 of the connecting pipe 8, the dewatering process in the foundation pit when the water-proof curtain isolates the aquifer can also be simulated.

[0026] Based on the above device and working principle, the experimental method of the present invention is:

[0027] Step 1: Before the test starts, under the condition of 1g, fill the main model box 1 with the simulated soil 24; and inject dyed simulated groundwater into the main model box 1 and the auxiliary model box 2 to the static water level 25; adjust the height of the air inlet pipe 13 to the static water level 25, and insert the outlet pipe 14 into the bottom of the auxiliary model box 2; open the one-way exhaust valve 12 and the one-way valve 23.

[0028] Step 2: After the test starts, turn on the centrifuge and accelerate to the test designed centrifugal acceleration, start the variable frequency water pump 17, and control the dynamic water level 26 by adjusting the power of the variable frequency water pump 17. The water pumped from the pipe well 16 enters the water storage tank 3 through the water pipe 18 for temporary storage. At this time, the water level in the main model box 1 becomes the dynamic water level 26. The image acquisition equipment in the matching centrifugal field collects the dynamic water level 26 and the soil deformation process through the visual observation window.

[0029] In the above process, when the water level in the auxiliary model box 2 is lower than the static water level 25, the air in the auxiliary model box 2 enters the water storage tank 3 through the air inlet pipe 13; the water in the water storage tank 3 enters the auxiliary model box 2 through the water outlet pipe 14 until the liquid level in the auxiliary model box 2 rises and covers the opening of the air inlet pipe 13; the water outlet pipe 14 stops discharging water, and the liquid level in the auxiliary model box 2 is maintained at the static water level 25. The one-way exhaust valve 12 and the one-way valve 23 should always be in an open state.

[0030] When the connecting pipe 8 is provided with a valve 9, in the above step 1, the valve 9 can be opened or closed according to the test simulation working condition. Opening the valve 9 simulates the open pumping process. Closing the valve 9 can also simulate the pumping process in the foundation pit when the water-proof curtain separates the aquifer. When the valve 9 is closed, the water level of the auxiliary model box 2 does not drop, and the water in the water storage tank 3 does not replenish the auxiliary model box 2.

[0031] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be regarded as the scope of protection of the present invention.

Claims

1. A groundwater well pumping simulation device for centrifugal model test, characterized in that: The underground water pipe well pumping simulation device is arranged on the hanging bucket of the centrifuge; the underground water pipe well pumping simulation device comprises a main model box (1) for filling with simulated soil (24) and simulated groundwater, a secondary model box (2) for filling with the simulated groundwater, a water storage tank (3) and a pumping system (4); the secondary model box (2) is located on the side of the main model box (1) and is connected to the main model box (1) through a connecting pipe (8) at the bottom; the water storage tank (3) is installed above the secondary model box (2) and a one-way exhaust valve (12) is installed on the top; the bottom opening of the water storage tank (3) is provided with an air inlet pipe (13) and a water outlet pipe (14), and the air inlet pipe (13) and the water outlet pipe (14) extend downward into the secondary model box (2). The model box (2) is provided with a pumping system (4) controlled by a variable frequency water pump (17), comprising a pipe well (16) and a water guide pipe (18); the pipe well (16) extends into the main model box (1); below the pipe well (16) is an opening section (19) filled with filter material (20); one end of the water guide pipe (18) is connected to the pipe well (16), and the other end extends into the water storage tank (3); a one-way valve (23) is installed on the water guide pipe (18); visual observation windows are provided on the sides of the main model box (1), the auxiliary model box (2) and the water storage tank (3); a valve (9) is provided on the connecting pipe (8); there are two auxiliary model boxes (2), which are symmetrically arranged on both sides of the main model box (1).

2. The simulation device according to claim 1, characterized in that: There are multiple pumping systems (4), and the variable frequency water pumps (17) of each pumping system (4) are independently controlled.

3. The simulation device according to claim 1, characterized in that: The connecting pipe (8) is located at the main model box (1) and is provided with a first reverse filtering device (10); the air inlet pipe (13) and the water outlet pipe (14) are located at the water storage tank (3) and are provided with a second reverse filtering device (15).

4. The simulation device according to claim 1, characterized in that: The control line (22) of the variable frequency water pump (17) is connected to the slip ring of the centrifuge and then connected to a control room outside the centrifuge.

5. The test method of the underground water pipe well pumping simulation device for centrifugal model test according to claim 1, characterized in that: Step 1: Before the test begins, under the condition of 1g, the main model box (1) is filled with the simulated soil (24); and the dyed simulated groundwater is injected into the main model box (1) and the auxiliary model box (2) to the static water level (25); the height of the air inlet pipe (13) is adjusted to the static water level (25), and the water outlet pipe (14) is inserted into the lower part of the auxiliary model box (2); the one-way exhaust valve (12) is opened; and the one-way valve (23) is opened; Step 2: After the test begins, the centrifuge is turned on and accelerated to the test designed centrifugal acceleration, the variable frequency water pump (17) is started, and the dynamic water level (26) is controlled by adjusting the power of the variable frequency water pump (17). The water pumped from the pipe well (16) enters the water storage tank (3) through the water guide pipe (18) for temporary storage. At this time, the water level in the main model box (1) becomes the dynamic water level (26); the image acquisition device in the supporting centrifugal field acquires the dynamic water level (26) and the soil deformation process through the visual observation window.

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