Active anti-floating drainage model test device and test method considering saturation changes

Abstract

The present invention discloses an active anti-floating drainage model test device and test method that considers saturation changes, belonging to the technical field of active anti-floating technology for buildings. The test device comprises: a boundary model box, a building model box, multiple pore pressure sensors and multiple dielectric constant sensors, a pressure-limiting drainage pipe that simulates the active anti-floating equipment in an actual building, a water head control device, and a rainfall simulation device. The test device can simulate the seepage field of the underground space under the conditions of active anti-floating measures during rainfall and reproduce the drainage conditions of the underground space under such conditions. The pore pressure sensors and the dielectric constant sensors monitor the changes in soil saturation in real time, filling the gap in the soil saturation change factors of existing test devices of this type. The test device can demonstrate the drainage conditions and seepage laws of the active anti-floating measures in the process of soil transition from unsaturation to saturation under different rainfall and different stratum conditions, providing a scientific basis and data support for the optimized application of active anti-floating measures under different saturation conditions.

Description

Technical Field

[0001] The invention relates to the technical field of active anti-floating technology for buildings, and in particular to an active anti-floating drainage model test device and a test method taking saturation changes into consideration. Background Art

[0002] During construction and operation, underground structures (such as basements, underground garages, and subway tunnels) often face anti-floating stability challenges caused by groundwater buoyancy. Traditional anti-floating technologies rely on counterweights, anchor bolts, or passive drainage. However, these methods are often designed based on static hydrogeological conditions and fail to fully consider the impact of dynamic changes in soil saturation on anti-floating drainage performance. In recent years, with the frequent occurrence of extreme climate events and the expansion of underground space development into complex geological environments, the problem of unsaturated-to-saturated soil transitions caused by groundwater level fluctuations, rainfall infiltration, and localized seepage has become increasingly prominent. Changes in soil saturation not only directly affect permeability, matrix suction, and effective stress distribution, but also alter the buoyancy mechanism and response characteristics of the drainage system, thereby threatening the anti-floating safety of the structure. Therefore, developing an active anti-floating drainage model test device and method that can simulate dynamic changes in saturation and reveal the relationship between saturation and anti-floating drainage performance is key to improving the reliability of anti-floating designs.

[0003] Existing anti-floating model test research has largely focused on drainage efficiency and buoyancy balance mechanisms under saturated soil conditions, while paying insufficient attention to the dynamic processes in the unsaturated-saturated transition zone. For example, traditional drainage model test devices often control saturation conditions through a fixed water level, making it impossible to achieve continuous and precise control of soil saturation and, therefore, unable to simulate the non-uniform saturation distribution caused by rainfall, evaporation, or seepage in actual projects. Furthermore, existing test methods often employ passive drainage modes and lack active feedback control mechanisms based on real-time saturation monitoring, resulting in deviations between test results and the actual response to complex hydrogeological conditions. While theoretically mature models of unsaturated soil mechanics for the variation of matrix suction and permeability with saturation (such as the van Genuchten model) are available, their coupling with anti-floating drainage dynamics remains exploratory, particularly with a lack of experimental verification of the dynamic control of active drainage systems.

[0004] In recent years, a small number of researchers have begun to focus on the impact of unsaturated soil on its anti-floating stability. Studies have shown that when the soil saturation changes from unsaturated to saturated, the permeability coefficient increases nonlinearly, and the timeliness of the drainage path is significantly reduced. At the same time, the loss of matrix suction weakens the soil's own shear strength, exacerbating the risk of structural floating. However, existing studies have mostly indirectly deduced the impact of saturation through numerical simulations or simplified indoor experiments, lacking a physical model test platform that can truly reflect the saturation-seepage-mechanical coupling effect. In addition, the design of active anti-floating drainage systems requires clear start-stop control strategies under different saturation thresholds. However, existing test equipment makes it difficult to achieve dynamic interaction between saturation parameters and drainage behavior, which restricts the optimization and verification of active control algorithms.

[0005] In summary, given the impact of dynamic saturation changes on anti-floating drainage systems, there is an urgent need to develop an active anti-floating drainage model test device that can precisely control and monitor soil saturation, as well as establish a supporting test method. Physical simulations can reveal the inherent laws of drainage efficiency, buoyancy evolution, and structural response during the unsaturated-to-saturated transition process, providing theoretical support and technical basis for the adaptive design of anti-floating systems under complex hydrological conditions. Summary of the Invention

[0006] The purpose of the present invention is to provide an active anti-floating drainage model test device and test method that takes into account saturation changes, so as to solve the problem that traditional drainage model test devices lack a mechanism based on real-time soil saturation monitoring, resulting in deviations between test results and actual responses under complex hydrogeological conditions.

[0007] To achieve the above objectives, the present invention provides the following technical solutions:

[0008] The active anti-floating drainage model test device considering saturation change provided by the present invention comprises: a boundary model box and a building model box fixedly arranged in the boundary model box;

[0009] A plurality of pore pressure sensors and a plurality of dielectric constant sensors are embedded in the boundary model box;

[0010] A pressure-limiting drainage pipe for simulating active anti-floating equipment in an actual building is provided at the bottom of the building model box.

[0011] Furthermore, a plurality of bolts are provided at the bottom of the building model box, and the other ends of the plurality of bolts are fixedly connected to the boundary model box.

[0012] Furthermore, there are multiple pressure-limiting drainage pipes, and the lengths and end positions of the multiple pressure-limiting drainage pipes are adjustable.

[0013] Furthermore, the active anti-floating drainage model test device that takes into account saturation changes also includes a head control device, which includes a drainage ditch arranged on the periphery of the top of the boundary model box, and the top height of the drainage ditch is flush with the top of the boundary model box; the drainage ditch is connected to the No. 2 water collecting tank through a pipe, and a No. 2 flow meter is installed on the pipe.

[0014] Furthermore, the interior of the boundary model box is used to fill and lay a simulated soil layer structure; a plurality of pore pressure sensors and a plurality of dielectric constant sensors are respectively buried at different height positions of the simulated soil layer structure.

[0015] Furthermore, the active anti-floating drainage model test device considering saturation change also includes a rainfall simulation device, which includes a water delivery pipeline, a No. 1 flow meter, a water pump, a No. 1 water collection tank and a telescopic bracket;

[0016] The water supply pipeline is arranged on the top of the boundary model box through a telescopic bracket, and the water supply pipeline is connected to the No. 1 water collecting tank through a hose, wherein the No. 1 flow meter and the water pump are arranged on the hose; a plurality of nozzles are arranged on the water supply pipeline, and the water spraying range of the plurality of nozzles covers the surface of the simulated soil layer structure.

[0017] The present invention also provides a test method for an active anti-floating drainage model test device considering saturation changes, which comprises the following steps:

[0018] S1. Lay soil layers in layers within the boundary model box, and install multiple pore pressure sensors and multiple dielectric constant sensors at different heights of the soil layers;

[0019] S2. Fixing the building model box inside the boundary model box with a plurality of bolts, so that the bottom of the building model box contacts the upper surface of the soil layer;

[0020] S3. Installing multiple pressure-limiting drainage pipes inside the building model box according to preset conditions, and adjusting the lengths and end positions of the multiple pressure-limiting drainage pipes;

[0021] S4. Install the drainage ditch on the outer periphery of the top of the boundary model box;

[0022] S5. Install a rainfall simulation device and adjust the height of the telescopic bracket so that the spray range of the multiple nozzles covers the upper surface of the simulated soil layer;

[0023] S6. Conduct multiple tests by changing rainfall conditions, soil structure conditions, and the arrangement of multiple pressure-limiting drainage pipes. After each test, collect monitoring data from the pore pressure sensor, dielectric constant sensor, flow meter No. 2, and flow meter No. 1 to obtain the groundwater seepage pattern of the active anti-floating equipment under different rainfall conditions, different soil structure conditions, different arrangements of multiple pressure-limiting drainage pipes, and changes in soil saturation.

[0024] Furthermore, in step S1, dielectric constant sensors and pore pressure sensors are buried in layers; during the laying of soil layers, soil samples are cut layer by layer, and permeability tests and moisture characteristic curve tests are carried out to ensure that the actual permeability coefficient and saturation evolution law of the soil are consistent with the design parameters; by laying different soil layers and initial saturation distributions, multiple groups of comparative experiments are repeated to analyze the impact of the non-uniform saturation field of the soil on the seepage path.

[0025] Furthermore, in step S6, the soil layer structure and the layout of the multiple pressure-limiting drainage pipes remain unchanged, and the rainfall conditions are changed. The monitoring data of the pore pressure sensor, the dielectric constant sensor, the second flow meter, and the first flow meter are used to obtain the groundwater seepage law of the active anti-floating equipment under different rainfall conditions and changes in soil saturation.

[0026] While the rainfall conditions and the layout of multiple pressure-limiting drainage pipes remain unchanged, the soil structure is changed. The monitoring data from the pore pressure sensor, dielectric constant sensor, No. 2 flow meter, and No. 1 flow meter are used to obtain the groundwater seepage pattern of the active anti-floating equipment under different soil structure conditions and changes in soil saturation.

[0027] While keeping rainfall and soil conditions unchanged, the layout of multiple pressure-limiting drainage pipes is changed. Through the monitoring data of pore pressure sensors, dielectric constant sensors, No. 2 flowmeter and No. 1 flowmeter, the groundwater seepage law of active anti-floating equipment under different layout conditions of multiple pressure-limiting drainage pipes and changes in soil saturation is obtained.

[0028] Furthermore, in step S6, the rainfall condition includes rainfall amount and rainfall time, wherein the simulation method of rainfall time is:

[0029] In a homogeneous isotropic medium, the cross-sectional one-dimensional confined water flow equations are:

[0030] ;

[0031] ;

[0032] in, K is the permeability coefficient, H is the water head, S s is the water storage rate,v is the flow rate, t For time, x is the horizontal coordinate;

[0033] Introducing a set of dimensionless ratios α H 、 α S 、 α K 、 α x 、 α t 、 α v :

[0034] ;

[0035] ;

[0036] ;

[0037] ;

[0038] ;

[0039] ;

[0040] K m 、 H m 、 S s,m 、 v m 、 x m 、 t m are the model quantities of permeability coefficient, hydraulic head, water storage rate, flow velocity, horizontal coordinate and time, K 、 H 、 S s 、 v 、 x 、 t are the prototype quantities of permeability coefficient, hydraulic head, water storage rate, flow rate, horizontal coordinates and time respectively;

[0041] After sorting, we get:

[0042] ;

[0043] ;

[0044] Let the combination of ratios satisfy the following formula:

[0045] ;

[0046] ;

[0047] By selecting different ratios, the groundwater seepage pattern under different rainfall durations can be simulated;

[0048] When the moisture content of the soil changes, the permeability coefficient in the above formula is K The value of will also change; the permeability coefficient K The calculation method is to accurately detect the moisture content by measuring the dielectric constant of the soil layer, and then use the soil's own water content and permeability coefficient K The corresponding relationship is used to obtain the permeability coefficient K The changing state of the value;

[0049] Fitting permeability coefficient with water content as variable K , the relationship is as follows:

[0050]

[0051] in, K θ Soil moisture content i The permeability coefficient at ; ks is the permeability coefficient of the soil in a fully saturated state; i is the volumetric water content; θs is the volumetric water content of the soil when fully saturated; i r is the residual moisture content, which is the critical point of permeability failure. i r When the soil is impermeable; m is the nonlinear index;

[0052] Dielectric constant and water content i The relationship formula is:

[0053]

[0054] in, It is the dielectric constant of the soil layer. During the test, the dielectric constant sensor is used for actual measurement. are empirical coefficients, , , , .

[0055] Based on the above technical solution, the present invention can produce at least the following technical effects:

[0056] The present invention provides a model test apparatus and method for active anti-floating drainage that considers saturation variations. These tests demonstrate the drainage performance and seepage patterns of active anti-floating measures during the transition from unsaturated to saturated soil under varying rainfall and ground conditions. The test method dynamically adjusts rainfall intensity, replaces soil layers with varying permeability characteristics, adjusts the spacing and elevation of pressure-limiting drain pipes, and uses dielectric constant sensors to monitor soil saturation distribution in real time. This method systematically reveals the groundwater seepage response mechanism of active anti-floating measures under the coupled effects of rainfall and soil structure. During the test, pore water pressure sensors and multiple dielectric constant sensors were embedded in layers at key soil sections to simultaneously collect dynamic data on volumetric water content versus saturation, pore water pressure evolution curves, and water discharge from the pressure-limiting drain pipes. Through multi-source data fusion, the test analyzes the uneven distribution of saturation within different soil layers during rainfall infiltration and drainage, as well as its impact on seepage paths. This method accurately simulates the seepage behavior of groundwater in the unsaturated-to-saturated transition zone, providing a scientific basis and data support for the optimized application of active anti-floating measures under varying saturation conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 It is a schematic diagram of the three-dimensional structure of the active anti-floating drainage model test device considering saturation changes of the present invention;

[0058] Figure 2 2. It is a front view structural schematic diagram of the active anti-floating drainage model test device considering saturation change of the present invention;

[0059] Figure 3 2. It is a schematic top view of the structure of the active anti-floating drainage model test device considering saturation changes of the present invention;

[0060] Figure 4 It is a side view structural schematic diagram of the active anti-floating drainage model test device considering saturation changes of the present invention;

[0061] Figure 5 It is a schematic diagram of the internal structure of the active anti-floating drainage model test device taking saturation changes into consideration according to the present invention.

[0062] In the figure: 1. Boundary model box, 2. Building model box, 3. Pressure-limiting drainage pipe, 4. Bolt, 5. Head control device, 6. Pore pressure sensor, 7. Dielectric constant sensor, 8. Water supply pipeline, 9. Nozzle, 10. Telescopic bracket, 11. Water pump, 12. Flow meter No. 1, 13. Flow meter No. 2, 14. Water collecting tank No. 1, 15. Water collecting tank No. 2. DETAILED DESCRIPTION

[0063] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making creative work shall fall within the scope of protection of the present invention.

[0064] Example 1

[0065] See also Figure 1 to Figure 5 The active anti-floating drainage model test device considering saturation changes includes a boundary model box 1 and a building model box 2 fixedly arranged within the boundary model box 1. Specifically, a plurality of bolts 4 are provided at the bottom of the building model box 2, and the other ends of the plurality of bolts 4 are fixedly connected to the boundary model box 1, fixing the relative position between the boundary model box 1 and the boundary model box 1.

[0066] A plurality of pore pressure sensors 6 and a plurality of dielectric constant sensors 7 are embedded in the boundary model box 1 .

[0067] In this embodiment, the interior of the boundary model box 1 is used to fill and lay a simulated soil layer structure; the multiple pore pressure sensors 6 and the multiple dielectric constant sensors 7 are respectively buried at different height positions of the simulated soil layer structure.

[0068] The bottom of the building model box 2 is equipped with a pressure-limiting drainage pipe 3 to simulate the active anti-floating equipment in an actual building. To facilitate subsequent testing, multiple pressure-limiting drainage pipes 3 are provided, and the length and end positions of the multiple pressure-limiting drainage pipes 3 are adjustable to better simulate the active anti-floating equipment in an actual building.

[0069] The test device provided in this embodiment further includes a water head control device 5 and a rainfall simulation device.

[0070] Specifically, the hydraulic head control device 5 includes a drainage ditch disposed around the top periphery of the boundary model box 1, with the top of the drainage ditch flush with the top of the boundary model box 1. The drainage ditch is connected to the second water collection tank 15 via a pipe, wherein the pipe is equipped with a second flow meter 13. The drainage ditch collects water overflowing from the boundary model box 1 and discharges it into the second water collection tank 15. The second flow meter 13 records the amount of water overflowing from the boundary model box 1. The main function of the hydraulic head control device 5 is to achieve hydraulic head stability in the soil within the boundary model box 1.

[0071] Specifically, the rainfall simulation device includes a water supply pipe 8, a No. 1 flow meter 12, a water pump 11, a No. 1 water collecting tank 14 and a telescopic bracket 10; the water supply pipe 8 is arranged on the top of the boundary model box 1 through the telescopic bracket 10, and the water supply pipe 8 is connected to the No. 1 water collecting tank 14 through a hose, wherein the No. 1 flow meter 12 and the water pump 11 are arranged on the hose; a plurality of nozzles 9 are arranged on the water supply pipe 8, and the water spraying range of the plurality of nozzles 9 covers the surface of the simulated soil structure.

[0072] Start the water pump 11, which pumps water from the No. 1 water collecting tank 14 into the water supply pipe 8, and sprays the water onto the surface of the simulated soil structure through multiple nozzles 9 to simulate actual rainfall. The size and time of the rainfall can be controlled by the No. 1 flow meter 12 to simulate different rainfall conditions in actual situations.

[0073] The principle behind the active anti-floating drainage model test device is that the physical phenomena of seepage in the prototype active anti-floating device in an actual building and the model simulated by the pressure-limited drain pipe 3 obey the same groundwater dynamics. If similar boundary conditions are given, they should have similar solutions. Thus, these physical entities are combined to form a similar model, and the similar solutions of the model can be used to simulate the seepage laws in porous media. This method is more convenient than using the prototype active anti-floating device, reducing the size of the seepage zone, accelerating the seepage rate, and saving time. Furthermore, using the pressure-limited drain pipe 3 simulation model simplifies its preparation, facilitates control and measurement, and allows the order of magnitude of certain variables and parameters to be changed to improve measurement accuracy.

[0074] Example 2

[0075] This embodiment is based on the test method of the active anti-floating drainage model test device considering saturation changes provided in the first embodiment, and includes the following steps:

[0076] S1. Lay soil layers in layers within the boundary model box 1, and install multiple pore pressure sensors 6 and multiple dielectric constant sensors 7 at different heights of the soil layers. Specifically, in step S1, the dielectric constant sensors 7 and the pore pressure sensors 6 are buried in layers. During the laying of the soil layers, soil samples are cut layer by layer, and permeability tests and moisture characteristic curve tests are performed to ensure that the actual permeability coefficient and saturation evolution law of the soil are consistent with the design parameters. By laying different soil layers and initial saturation distributions, multiple groups of comparative experiments are repeated to analyze the impact of the non-uniform saturation field of the soil on the seepage path.

[0077] S2. Fix the building model box 2 inside the boundary model box 1 by using a plurality of bolts 4, so that the bottom of the building model box 2 contacts the upper surface of the soil layer;

[0078] S3. Install the multiple pressure-limiting drainage pipes 3 inside the building model box 2 according to preset conditions, and adjust the lengths and end positions of the multiple pressure-limiting drainage pipes 3;

[0079] S4, installing the drainage ditch on the top periphery of the boundary model box 1;

[0080] S5. Install the rainfall simulation device and adjust the height of the telescopic bracket 10 so that the water spray range of the multiple nozzles 9 covers the upper surface of the simulated soil layer;

[0081] S6. Conduct multiple groups of tests by changing rainfall conditions, soil structure conditions, and the arrangement of multiple pressure-limiting drainage pipes 3. After each group of tests is completed, collect monitoring data from the pore pressure sensor 6, the dielectric constant sensor 7, the No. 2 flow meter 13, and the No. 1 flow meter 12 to obtain the groundwater seepage law of the active anti-floating equipment under different rainfall conditions, different soil structure conditions, different arrangements of multiple pressure-limiting drainage pipes 3, and changes in soil saturation.

[0082] In step S6, the soil layer structure and the layout of the multiple pressure-limiting drainage pipes 3 remain unchanged, but the rainfall conditions are changed. The monitoring data of the pore pressure sensor 6, the dielectric constant sensor 7, the second flow meter 13, and the first flow meter 12 are used to obtain the groundwater seepage law of the active anti-floating device under different rainfall conditions and changes in soil saturation.

[0083] While the rainfall conditions and the layout of the multiple pressure-limiting drainage pipes 3 remain unchanged, the soil structure is changed. Through the monitoring data of the pore pressure sensor 6, the dielectric constant sensor 7, the second flow meter 13 and the first flow meter 12, the groundwater seepage law of the active anti-floating device under different soil structure conditions and changes in soil saturation is obtained;

[0084] While keeping rainfall and soil conditions unchanged, the layout of the multiple pressure-limiting drainage pipes 3 is changed, and the monitoring data of the pore pressure sensor 6, the dielectric constant sensor 7, the No. 2 flowmeter 13 and the No. 1 flowmeter 12 are used to obtain the groundwater seepage law of the active anti-floating equipment under different layout conditions of the multiple pressure-limiting drainage pipes 3 and changes in soil saturation.

[0085] The layout of multiple pressure-limiting drain pipes 3 includes, but is not limited to, variations in the number, pressure limit, spacing, length, and end elevation of the pressure-limiting drain pipes 3. The test method for the active anti-floating drainage model test device considering saturation variation can analyze the impact of soil saturation variation on the permeability coefficient of a building equipped with active anti-floating equipment under the coupled influence of various soil layer structures, various pressure-limiting drain pipe 3 layouts, and rainfall conditions, thereby studying the laws of groundwater infiltration.

[0086] In step S6, the rainfall conditions include rainfall amount and rainfall time, wherein the simulation method of rainfall time is:

[0087] In a homogeneous isotropic medium, the cross-sectional one-dimensional confined water flow equations are:

[0088] ;

[0089] ;

[0090] in, K is the permeability coefficient, H is the water head, S s is the water storage rate, v is the flow rate, t For time, x is the horizontal coordinate;

[0091] Introducing a set of dimensionless ratios α H 、 α S 、 α K 、 α x 、 α t 、 α v :

[0092] ;

[0093] ;

[0094] ;

[0095] ;

[0096] ;

[0097] ;

[0098] K m 、 H m 、 S s,m 、 v m 、 x m 、 t m are the model quantities of permeability coefficient, hydraulic head, water storage rate, flow velocity, horizontal coordinate and time, K 、 H、 S s 、 v 、 x 、 t are the prototype quantities of permeability coefficient, hydraulic head, water storage rate, flow rate, horizontal coordinates and time respectively;

[0099] After sorting, we get:

[0100] ;

[0101] ;

[0102] Let the combination of ratios satisfy the following formula:

[0103] ;

[0104] ;

[0105] By selecting different ratios, the groundwater seepage pattern under different rainfall durations can be simulated;

[0106] When the moisture content of the soil changes, the permeability coefficient in the above formula is K The value of will also change, but there is no method in the prior art that can directly measure the permeability coefficient. K The sensing device, in this embodiment, has a permeability coefficient K The calculation method is to accurately detect the moisture content by measuring the dielectric constant of the soil layer, and then use the soil's own water content and permeability coefficient K The corresponding relationship is used to obtain the permeability coefficient K The changing state of the value;

[0107] Fitting permeability coefficient with water content as variable K , the relationship is as follows:

[0108]

[0109] in, K θ Soil moisture content i The permeability coefficient at ; ks is the permeability coefficient of the soil in a fully saturated state; i is the volumetric water content; θs is the volumetric water content of the soil when fully saturated; i r is the residual moisture content, which is the critical point of permeability failure. i r When the soil is impermeable; m is the nonlinear index;

[0110] Dielectric constant and water content i The relationship formula is:

[0111]

[0112] in, It is the dielectric constant of the soil layer. During the test, the dielectric constant sensor is used for actual measurement. are empirical coefficients, , , , For example, suppose α K =1, α S =1, α x =1:20, α H =1:20; Substitute into the above formula and calculate: α t =1:400, α v =1; when the model ratio is determined, the time ratio α t is a fixed number. According to the above example, when simulating 10 days of continuous rainfall, the required test time is: T=10*24*3600 / 400s=2160s=36min.

[0113] When rainfall begins, the soil is in an unsaturated state. As rainfall infiltrates into the soil, the soil's water content gradually increases, and the permeability coefficient changes accordingly. At this time, the dielectric constant sensor 7 in the soil can quickly measure the change in water content and calculate the permeability coefficient. K The discharge data from pressure-limited drain pipe 3 can be used to study the groundwater seepage patterns under varying water content using active anti-floating measures. During heavy rainfall, the soil gradually reaches saturation, and rainfall is discharged through both infiltration and surface runoff.

[0114] In summary, the active anti-floating drainage model test apparatus and test method considering saturation variation can demonstrate the drainage performance and seepage patterns of active anti-floating measures during the transition from unsaturated to saturated soil under varying rainfall and ground conditions. By dynamically adjusting rainfall intensity, changing soil layers with varying permeability characteristics, adjusting the spacing and elevation of the pressure-limiting drainage pipes (3), and integrating a dielectric constant sensor (7) to monitor soil saturation distribution in real time, the test method systematically reveals the groundwater seepage response mechanism of active anti-floating measures under the coupled effects of rainfall and soil structure. During the test, pore pressure sensors 6 and multiple dielectric constant sensors 7 were buried in layers at key sections of the soil layer to simultaneously collect dynamic data on volumetric water content-saturation, pore water pressure evolution curves, and water discharge from the pressure-limiting drain pipe 3. Through multi-source data fusion, the uneven distribution of saturation in different soil layer structures and its impact on the seepage path during rainfall infiltration and drainage were analyzed, and the seepage behavior in the unsaturated-saturated transition zone of groundwater was accurately simulated. This fills the gap in the existing test equipment of this type in soil saturation change factors and provides a scientific basis and data support for the optimized application of active anti-floating measures under different saturation conditions.

[0115] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "provided with," "mounted / connected," and "connected" should be understood in a broad sense. For example, "connected" can mean 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 an indirect connection through an intermediate medium, and it can be internal communication between two components. Those skilled in the art will be able to understand the specific meanings of the above terms in the present invention in specific circumstances.

[0116] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A test method for an active anti-floating drainage model test device considering saturation changes, characterized in that: The active anti-floating drainage model test device includes a boundary model box, a building model box, a water head control device and a rainfall simulation device; A plurality of pore pressure sensors and a plurality of dielectric constant sensors are buried inside the boundary model box; the interior of the boundary model box is used to fill and lay a simulated soil layer structure; the plurality of pore pressure sensors and the plurality of dielectric constant sensors are respectively buried at different height positions of the simulated soil layer structure; The bottom of the building model box is provided with a pressure-limiting drainage pipe for simulating the active anti-floating equipment in an actual building; the bottom of the building model box is provided with a plurality of bolts, the other ends of the plurality of bolts are fixedly connected to the boundary model box; the number of the pressure-limiting drainage pipes is multiple, and the length and end positions of the plurality of pressure-limiting drainage pipes are adjustable; The water head control device includes a drainage ditch arranged on the periphery of the top of the boundary model box, the top height of the drainage ditch is flush with the top of the boundary model box; the drainage ditch is connected to the No. 2 water collecting tank through a pipe, wherein a No. 2 flow meter is installed on the pipe; The rainfall simulation device includes a water pipeline, a No. 1 flow meter, a water pump, a No. 1 water collecting tank, and a telescopic bracket; the water pipeline is arranged on the top of the boundary model box through the telescopic bracket, and the water pipeline is connected to the No. 1 water collecting tank through a hose, wherein the No. 1 flow meter and the water pump are arranged on the hose; a plurality of nozzles are arranged on the water pipeline, and the water spray range of the plurality of nozzles covers the surface of the simulated soil structure; The test method comprises the following steps: S1. Lay soil layers in layers within the boundary model box and install multiple pore pressure sensors and multiple dielectric constant sensors at different heights in the soil layers. Bury the dielectric constant sensors and pore pressure sensors in layers. During the soil layer laying process, cut soil samples layer by layer and conduct permeability tests and moisture characteristic curve tests to ensure that the actual permeability coefficient and saturation evolution of the soil are consistent with the design parameters. Repeat multiple sets of comparative experiments by laying different soil layers and initial saturation distributions to analyze the impact of the non-uniform soil saturation field on the seepage path. S2. Fixing the building model box inside the boundary model box with a plurality of bolts, so that the bottom of the building model box contacts the upper surface of the soil layer; S3. Install multiple pressure-limiting drainage pipes inside the building model box according to preset conditions, and adjust the lengths and end positions of the multiple pressure-limiting drainage pipes; S4. Install the drainage ditch on the outer periphery of the top of the boundary model box; S5. Install a rainfall simulation device and adjust the height of the telescopic bracket so that the spray range of the multiple nozzles covers the upper surface of the simulated soil layer; S6. Conduct multiple tests by varying rainfall conditions, soil structure conditions, and the arrangement of multiple pressure-limiting drainage pipes. After each test, collect monitoring data from the pore pressure sensor, dielectric constant sensor, No. 2 flowmeter, and No. 1 flowmeter to obtain groundwater seepage patterns for the active anti-floating device under different rainfall conditions, different soil structure conditions, different arrangements of multiple pressure-limiting drainage pipes, and changes in soil saturation. While the soil structure and the arrangement of multiple pressure-limiting drainage pipes remain unchanged and rainfall conditions are varied, obtain monitoring data from the pore pressure sensor, dielectric constant sensor, No. 2 flowmeter, and No. 1 flowmeter to obtain groundwater seepage patterns for the active anti-floating device under different rainfall conditions and changes in soil saturation. While the rainfall conditions and the layout of multiple pressure-limiting drainage pipes remain unchanged, the soil structure is changed. The monitoring data from the pore pressure sensor, dielectric constant sensor, No. 2 flow meter, and No. 1 flow meter are used to obtain the groundwater seepage pattern of the active anti-floating equipment under different soil structure conditions and changes in soil saturation. While keeping rainfall and soil conditions unchanged, the layout of multiple pressure-limiting drainage pipes was changed. Monitoring data from pore pressure sensors, dielectric constant sensors, flowmeter No. 2, and flowmeter No. 1 were used to obtain the groundwater seepage patterns of the active anti-floating equipment under different layouts of multiple pressure-limiting drainage pipes and changes in soil saturation. Rainfall conditions include rainfall amount and rainfall time, and the simulation method of rainfall time is: In a homogeneous isotropic medium, the cross-sectional one-dimensional confined water flow equations are: ； ； in, K is the permeability coefficient, H is the water head, S s is the water storage rate, v is the flow rate, t For time, x is the horizontal coordinate; Introducing a set of dimensionless ratios α H 、 α S 、 α K 、 α x 、 α t 、 α v : ； ； ； ； ； ； in, K m 、 H m 、 S s,m 、 v m 、 x m 、 t m are the model quantities of permeability coefficient, hydraulic head, water storage rate, flow velocity, horizontal coordinate and time, K 、 H 、 S s 、 v 、 x 、 t are the prototype quantities of permeability coefficient, hydraulic head, water storage rate, flow rate, horizontal coordinates and time respectively; After sorting, we get: ； ； Let the combination of ratios satisfy the following formula: ； ； By selecting different ratios, the groundwater seepage pattern under different rainfall durations can be simulated; When the moisture content of the soil changes, the permeability coefficient in the above formula is K The value of will also change; the permeability coefficient K The calculation method is to accurately detect the moisture content by measuring the dielectric constant of the soil layer, and then use the soil's own water content and permeability coefficient K The corresponding relationship is used to obtain the permeability coefficient K The changing state of the value; Fitting permeability coefficient with water content as variable K , the relationship is as follows: in, K θ Soil moisture content θ The permeability coefficient at ; ks is the permeability coefficient of the soil in a fully saturated state; θ is the volumetric water content; θs is the volumetric water content of the soil when fully saturated; θ r is the residual moisture content, which is the critical point of permeability failure. θ r When the soil is impermeable; m is the nonlinear index; Dielectric constant and water content θ The relationship formula is: in, It is the dielectric constant of the soil layer. During the test, the dielectric constant sensor is used for actual measurement. are empirical coefficients, , , , .

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