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

Abstract

The invention discloses an active anti-floating drainage model test device and test method considering saturation change, and belongs to the technical field of active anti-floating of buildings. The test device comprises a boundary model box, a building model box, a plurality of pore pressure sensors, a plurality of dielectric constant sensors, a pressure limiting drainage pipe for simulating active anti-floating equipment in an actual building, a water head control device and a rainfall simulation device, and can simulate a seepage field of an underground space under the condition of active anti-floating measures during rainfall. The drainage condition of the underground space under the condition is reproduced; the pore pressure sensor and the dielectric constant sensor monitor the saturation change of the soil body in real time, the vacancy of the existing test device in the saturation change factor of the soil body is filled up, the drainage condition of the active anti-floating measure and the seepage law of the soil body in the unsaturated-saturated transition process of the soil body under different rainfall and different stratum conditions can be demonstrated, and the test device has a wide application prospect. Scientific basis and data support are provided for optimization application of active anti-floating measures under different saturation working conditions.

Description

Technical Field

[0001] The present invention relates to the technical field of active anti - floating technology for buildings, and particularly to an active anti - floating drainage model test device and test method considering saturation change. Background Art

[0002] Underground structures (such as basements, underground garages, subway tunnels, etc.) often face the problem of anti - floating stability caused by groundwater buoyancy during construction and operation. Traditional anti - floating technologies mostly rely on means such as the counterweight method, anchor anti - floating, or passive drainage and pressure reduction. However, these methods are often designed based on static hydro - geological conditions and do not fully consider the influence of the dynamic change of soil saturation on the anti - floating drainage efficiency. In recent years, with the frequent occurrence of extreme climates and the extension of underground space development to complex geological environments, the problem of the transformation of soil from unsaturated to saturated state caused by groundwater level fluctuations, rainfall infiltration, and local seepage has become increasingly prominent. The change of soil saturation not only directly affects its permeability, matrix suction, and effective stress distribution, but also changes the buoyancy action mechanism and the 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 the dynamic change of saturation and revealing the correlation law between saturation and anti - floating drainage performance have become the key to improving the reliability of anti - floating design.

[0003] Existing anti - floating model test studies mostly focus on the drainage efficiency and buoyancy balance mechanism under saturated soil conditions, and pay insufficient attention to the dynamic process in the unsaturated - saturated transition interval. For example, traditional drainage model test devices often control the saturated condition by fixing the water level, unable to achieve continuous and precise regulation of soil saturation, and it is difficult to simulate the non - uniform saturation distribution in actual projects caused by rainfall, evaporation, or seepage. In addition, existing test methods mostly adopt the passive drainage mode, lacking an active feedback control mechanism based on real - time saturation monitoring, resulting in a deviation between the test results and the actual response of complex hydro - geological conditions. At the theoretical level, although the models in unsaturated soil mechanics regarding the change of matrix suction and permeability coefficient with saturation (such as the van Genuchten model) are relatively mature, their coupled analysis with anti - floating drainage dynamics is still in the exploratory stage, especially lacking experimental verification for the dynamic regulation of the active drainage system.

[0004] In recent years, a small number of scholars have begun to focus on the influence of unsaturated soil on anti - floating stability. Research shows that when the soil saturation changes from unsaturated to saturated state, the permeability coefficient increases non - linearly, and the timeliness of the drainage path decreases significantly. At the same time, the loss of matrix suction will weaken the shear strength of the soil itself and exacerbate the risk of the structure floating up. However, existing research mostly indirectly infers the influence of saturation through numerical simulation or simplified indoor tests, lacking a physical model test platform that can truly reflect the saturation - seepage - mechanics coupling effect. In addition, the design of the active anti - floating drainage system requires clear start - stop control strategies under different saturation thresholds, while existing test devices are difficult to achieve the dynamic interaction between saturation parameters and drainage behavior, restricting the optimization and verification of active control algorithms.

[0005] In summary, aiming at the influence mechanism of dynamic saturation changes on the anti - floating drainage system, it is urgent to develop an active anti - floating drainage model test device that can accurately regulate and monitor soil saturation, and establish a supporting test method. Revealing the internal laws of drainage efficiency, buoyancy evolution and structural response during the unsaturated - saturated transition process through physical simulation can provide theoretical support and technical basis for the adaptive design of anti - floating systems under complex hydrogeological 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 considering saturation changes, so as to solve the problem that the traditional drainage model test device lacks a mechanism based on real - time soil saturation monitoring, resulting in a deviation between the test results and the actual response of complex hydrogeological conditions.

[0007] To achieve the above purpose, the present invention provides the following technical solutions: The active anti - floating drainage model test device considering saturation changes provided by the present invention includes: a boundary model box and a building model box fixedly arranged in the boundary model box; A plurality of pore - pressure sensors and a plurality of dielectric constant sensors are buried inside the boundary model box; A pressure - limited drainage pipe for simulating the active anti - floating equipment in an actual building is arranged at the bottom of the building model box.

[0008] Furthermore, a plurality of bolts are arranged 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.

[0009] Furthermore, the number of the pressure - limited drainage pipes is multiple, and the lengths and end positions of the multiple pressure - limited drainage pipes are adjustable.

[0010] Furthermore, the active anti-floating drainage model test device considering saturation change further includes a water head control device. The water head control device includes a drainage groove arranged on the outer periphery of the top of the boundary model box, and the top height of the drainage groove is flush with the top of the boundary model box; the drainage groove is connected to the second water collection tank through a pipeline, and a second flowmeter is installed on the pipeline.

[0011] Furthermore, the interior of the boundary model box is used for filling and laying a simulated soil layer structure; a plurality of the pore pressure sensors and a plurality of dielectric constant sensors are respectively buried at different height positions of the simulated soil layer structure.

[0012] Furthermore, the active anti-floating drainage model test device considering saturation change further includes a rainfall simulation device. The rainfall simulation device includes a water delivery pipeline, a first flowmeter, a water pump, a first water collection tank and a telescopic support; The water delivery pipeline is arranged on the top of the boundary model box through the telescopic support, and the water delivery pipeline is communicated with the first water collection tank through a hose, and the first flowmeter and the water pump are arranged on the hose; a plurality of nozzles are arranged on the water delivery pipeline, and the water spraying ranges of the plurality of nozzles cover the surface of the simulated soil layer structure.

[0013] The present invention also provides a test method for the active anti-floating drainage model test device considering saturation change, which includes the following steps: S1. Lay the soil layer in layers in the boundary model box, and install a plurality of pore pressure sensors and a plurality of dielectric constant sensors at different height positions of the soil layer; S2. Install and fix the building model box in the boundary model box through a plurality of bolts, and the bottom of the building model box is in contact with the upper surface of the soil layer; S3. Install a plurality of pressure-limiting drain pipes in the building model box according to preset conditions, and adjust the lengths and end positions of the plurality of pressure-limiting drain pipes; S4. Install the drainage groove on the outer periphery of the top of the boundary model box; S5. Install the rainfall simulation device, and adjust the height of the telescopic support so that the water spraying ranges of the plurality of nozzles cover the upper surface of the simulated soil layer; S6. Conduct multiple groups of tests by changing the rainfall conditions, soil layer structure conditions and the arrangement modes of the plurality of pressure-limiting drain pipes; after each group of tests is completed, collect the monitoring data of the pore pressure sensors, dielectric constant sensors, second flowmeter and first flowmeter, and obtain the groundwater seepage law of the active anti-floating device under different rainfall conditions, different soil layer structure conditions, different arrangement modes of the plurality of pressure-limiting drain pipes and the change of soil saturation.

[0014] Further, in step S1, the dielectric constant sensor and the pore pressure sensor are buried in layers; during the process of laying the soil layer, the soil sample is cut layer by layer, and the permeability test and the water characteristic curve test are carried out to ensure that the actual permeability coefficient and the saturation evolution law of the soil body are consistent with the design parameters; by laying different soil layers and the initial saturation distribution, multiple groups of comparative experiments are carried out repeatedly to analyze the influence of the non-uniform saturation field of the soil body on the seepage path.

[0015] Further, in step S6, the soil layer structure and the layout method of multiple pressure-limiting drain pipes remain unchanged, the rainfall conditions are changed, and the groundwater seepage law of the active anti-floating device is obtained through the monitoring data of the pore pressure sensor, the dielectric constant sensor, the second flowmeter, and the first flowmeter under different rainfall conditions and the saturation change of the soil layer soil body; The rainfall conditions and the layout method of multiple pressure-limiting drain pipes remain unchanged, the soil layer structure is changed, and the groundwater seepage law of the active anti-floating device is obtained through the monitoring data of the pore pressure sensor, the dielectric constant sensor, the second flowmeter, and the first flowmeter under different soil layer structure conditions and the saturation change of the soil layer soil body; The rainfall conditions and the soil layer conditions remain unchanged, the layout method of multiple pressure-limiting drain pipes is changed, and the groundwater seepage law of the active anti-floating device is obtained through the monitoring data of the pore pressure sensor, the dielectric constant sensor, the second flowmeter, and the first flowmeter under different layout methods of multiple pressure-limiting drain pipes and the saturation change of the soil layer soil body.

[0016] Further, in step S6, the rainfall conditions include the rainfall amount and the rainfall time, and the simulation method of the rainfall time is as follows: In a homogeneous and isotropic medium, the one-dimensional confined flow equation set in the cross-section is: ; ; Among them, K is the permeability coefficient, H is the water head, S s is the storage rate, v is the flow velocity, t is the time, x is the coordinate in the horizontal direction; Introduce a set of dimensionless ratios α H 、 α S 、 α K 、 α x 、 α t 、 α v : ; ; ; ; ; ; K m 、 H m 、 S s,m 、 v m 、 x m 、 t m are respectively the model quantities of hydraulic conductivity, hydraulic head, storage coefficient, flow velocity, horizontal coordinate, and time, K 、 H 、 S s 、 v 、 x 、 t are respectively the prototype quantities of hydraulic conductivity, hydraulic head, storage coefficient, flow velocity, horizontal coordinate, and time; After sorting out, we get: ; ; Let the combination of each ratio satisfy the following formula: ; ; By selecting different ratios, the groundwater seepage law under different rainfall durations can be simulated; When the water content in the soil layer changes, the value of the hydraulic conductivity K in the above formula will also change; the calculation method of the hydraulic conductivity K is to accurately detect the water content by measuring the soil dielectric constant of the soil layer, and then use the corresponding relationship between the water content of the soil body and the hydraulic conductivity K to obtain the change state of the value of the hydraulic conductivity K ; Fitting the hydraulic conductivity K with the water content as a variable, the relationship is as follows:

[0017] where, K θ The hydraulic conductivity of the soil at the water content θ ;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 it is fully saturated; θ r is the residual water content, which is the critical point of permeability failure. When it is lower than θ r the soil is impermeable; m is the non - linear index; The relationship formula between the dielectric constant and the water content θ is:

[0018] where, is the dielectric constant of the soil layer. During the test, the buried dielectric constant sensor is used for in - situ measurement; are all empirical coefficients, , , , .

[0019] Based on the above - mentioned technical solution, the present invention can at least produce the following technical effects: The active anti - floating drainage model test device and test method considering saturation change provided by the present invention can demonstrate the drainage situation of the active anti - floating measures and the seepage law of the soil mass during the transition process from unsaturated to saturated under different rainfall and different stratum conditions. The test method reveals the groundwater seepage response mechanism of the active anti - floating measures under the coupling action of rainfall - soil structure by dynamically adjusting the rainfall intensity, replacing the soil layer structure with different permeability characteristics, adjusting the spacing and elevation arrangement of the pressure - limiting drainage pipes, and combining the dielectric constant sensor to monitor the saturation distribution of the soil mass in real - time. During the test process, the pore - pressure sensors and multiple dielectric constant sensors are buried in layers at the key sections of the soil layer in the soil mass to synchronously collect the dynamic data of volumetric water content - saturation, the evolution curve of pore water pressure and the water discharge of the pressure - limiting drainage pipes. Through multi - source data fusion, analyze the non - uniform distribution law of saturation in different soil layer structures during the rainfall infiltration and drainage process and its influence on the seepage path, accurately simulate the seepage behavior in the groundwater unsaturated - saturated transition zone, and provide a scientific basis and data support for the optimized application of active anti - floating measures under different saturation conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a three - dimensional structural schematic diagram of the active anti - floating drainage model test device considering saturation change of the present invention; Figure 2 is a front - view structural schematic diagram of the active anti - floating drainage model test device considering saturation change of the present invention; Figure 3It is a top - view structural schematic diagram of the active anti - floating drainage model test device considering saturation change in the present invention; Figure 4 It is a side - view structural schematic diagram of the active anti - floating drainage model test device considering saturation change in the present invention; Figure 5 It is an internal structural schematic diagram of the active anti - floating drainage model test device considering saturation change in the present invention.

[0021] 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 - conveying pipeline, 9. Nozzle, 10. Telescopic support, 11. Water pump, 12. First flowmeter, 13. Second flowmeter, 14. First water - collecting tank, 15. Second water - collecting tank. Specific implementation mode

[0022] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention; obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative work belong to the scope of protection of the present invention.

[0023] Embodiment 1 Please refer to Figures 1 to 5 , the active anti - floating drainage model test device considering saturation change includes a boundary model box 1 and a building model box 2 fixedly arranged in the boundary model box 1. Specifically, a plurality of bolts 4 are arranged 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 to fix the relative positions between the boundary model box 1 and the building model box 1.

[0024] A plurality of pore - pressure sensors 6 and a plurality of dielectric constant sensors 7 are buried inside the boundary model box 1.

[0025] In this embodiment, the inside of the boundary model box 1 is used to fill and lay a simulated soil layer structure; the plurality of pore - pressure sensors 6 and the plurality of dielectric constant sensors 7 are respectively buried at different height positions of the simulated soil layer structure.

[0026] A pressure - limiting drainage pipe 3 for simulating the active anti - floating equipment in an actual building is arranged at the bottom of the building model box 2. For the convenience of subsequent tests, the number of the pressure - limiting drainage pipes 3 is multiple, and the lengths 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.

[0027] The test device provided in this embodiment further includes a head control device 5 and a rainfall simulation device.

[0028] Specifically, the water head control device 5 includes a drainage trench arranged on the outer periphery of the top of the boundary model box 1, and the top height of the drainage trench is flush with the top of the boundary model box 1; the drainage trench is connected to the second water collection tank 15 through a pipeline, and a second flowmeter 13 is installed on the pipeline. The drainage trench collects the water overflowing from the boundary model box 1 and discharges the collected water into the second water collection tank 15, and the second flowmeter 13 records the water volume of the water overflowing from the boundary model box 1. The main function of the water head control device 5 is to achieve the water head stability of the soil body in the boundary model box 1.

[0029] Specifically, the rainfall simulation device includes a water delivery pipeline 8, a first flowmeter 12, a water pump 11, a first water collection tank 14 and a telescopic support 10; the water delivery pipeline 8 is arranged on the top of the boundary model box 1 through the telescopic support 10, the water delivery pipeline 8 is communicated with the first water collection tank 14 through a hose, and the first flowmeter 12 and the water pump 11 are arranged on the hose; a plurality of nozzles 9 are arranged on the water delivery pipeline 8, and the water spraying ranges of the plurality of nozzles 9 cover the surface of the simulated soil layer structure.

[0030] Start the water pump 11, the water pump 11 pumps the water in the first water collection tank 14 into the water delivery pipeline 8 and sprays it onto the surface of the simulated soil layer structure through a plurality of nozzles 9 to simulate actual rainfall. The size and time of rainfall can be controlled through the first flowmeter 12, so as to simulate different rainfall conditions in actual situations.

[0031] The principle of the active anti-floating drainage model test device is as follows: In the prototype of the active anti-floating equipment in the actual building and the model simulated by the pressure-limiting drainage pipe 3, the physical phenomena of seepage obey the same groundwater dynamics laws. If similar definite solution conditions are given, they should have similar solutions. Therefore, a similar model is composed of the entities of these physical phenomena, and the seepage law in the porous medium can be simulated by using the similar solutions of the model. It is more convenient than using the prototype experiment of the active anti-floating equipment, can reduce the size of the seepage area, accelerate the seepage speed, save time, and at the same time use the model simulated by the pressure-limiting drainage pipe 3, making its preparation simple, easy to control and measure, and can change the order of magnitude of some variables and parameters to improve the measurement accuracy.

[0032] Embodiment 2 The test method of the active anti-floating drainage model test device considering the change of saturation degree provided in this embodiment based on Embodiment 1 includes the following steps: S1. Lay the soil layer in the boundary model box 1 in layers, and install multiple pore pressure sensors 6 and multiple dielectric constant sensors 7 at different height positions of the soil layer. Specifically, in step S1, the dielectric constant sensors 7 and pore pressure sensors 6 are buried in layers. During the process of laying the soil layer, cut the soil samples layer by layer, and conduct permeability tests and moisture characteristic curve tests to ensure that the actual permeability coefficient and saturation evolution law of the soil body are consistent with the design parameters. By laying different soil layers and initial saturation distributions, conduct multiple groups of comparative experiments repeatedly to analyze the influence of the non-uniform saturation field of the soil body on the seepage path.

[0033] S2. Install and fix the building model box 2 inside the boundary model box 1 through multiple bolts 4, and the bottom of the building model box 2 is in contact with the upper surface of the soil layer. S3. Install multiple pressure-limiting drain pipes 3 inside the building model box 2 according to preset conditions, and adjust the lengths and end positions of the multiple pressure-limiting drain pipes 3. S4. Install the drainage trench around the top of the boundary model box 1. S5. Install the rainfall simulation device, and adjust the height of the telescopic bracket 10 so that the spraying range of multiple nozzles 9 covers the upper surface of the simulated soil layer. S6. Conduct multiple groups of tests by changing the rainfall conditions, soil layer structure conditions, and the layout methods of multiple pressure-limiting drain pipes 3. After each group of tests is completed, collect the monitoring data of the pore pressure sensors 6, dielectric constant sensors 7, second flowmeter 13, and first flowmeter 12 to obtain the groundwater seepage law of the active anti-floating device under different rainfall conditions, different soil layer structure conditions, different layout methods of multiple pressure-limiting drain pipes 3, and the change of soil layer soil saturation.

[0034] In step S6, when the soil layer structure and the layout method of multiple pressure-limiting drain pipes 3 remain unchanged and the rainfall conditions are changed, the groundwater seepage law of the active anti-floating device under different rainfall conditions and the change of soil layer soil saturation can be obtained through the monitoring data of the pore pressure sensors 6, dielectric constant sensors 7, second flowmeter 13, and first flowmeter 12. When the rainfall conditions and the layout method of multiple pressure-limiting drain pipes 3 remain unchanged and the soil layer structure is changed, the groundwater seepage law of the active anti-floating device under different soil layer structure conditions and the change of soil layer soil saturation can be obtained through the monitoring data of the pore pressure sensors 6, dielectric constant sensors 7, second flowmeter 13, and first flowmeter 12. When the rainfall conditions and the soil layer conditions remain unchanged and the layout method of multiple pressure-limiting drain pipes 3 is changed, the groundwater seepage law of the active anti-floating device under different layout methods of multiple pressure-limiting drain pipes 3 and the change of soil layer soil saturation can be obtained through the monitoring data of the pore pressure sensors 6, dielectric constant sensors 7, second flowmeter 13, and first flowmeter 12.

[0035] The layout methods of multiple pressure-limiting drain pipes 3 include, but are not limited to, the variations in the number, pressure-limiting value, spacing, length, and end height position of the pressure-limiting drain pipes 3. The test method of the active anti-floating drainage model test device considering the saturation change can analyze the influence of the soil layer saturation change on the permeability coefficient when a building equipped with an active anti-floating device is affected by the mutual coupling of various soil layer structures, various layout methods of the pressure-limiting drain pipes 3, and rainfall conditions, and then study the groundwater seepage law.

[0036] In step S6, the rainfall conditions include rainfall amount and rainfall time, and the simulation method of the rainfall time is as follows: In a homogeneous and isotropic medium, the one-dimensional confined flow equations for the cross-section are: ; ; Among them, K is the permeability coefficient, H is the water head, S s is the storage rate, v is the flow velocity, t is the time, x is the coordinate in the horizontal direction; Introduce a set of dimensionless ratios α H , α S , α K , α x , α t , α v : ; ; ; ; ; ; K m , H m , S s,m , v m , x m , t mModel quantities of hydraulic conductivity, hydraulic head, specific storage, flow velocity, horizontal coordinate, and time, respectively, K and H 、 S s 、 v 、 x 、 t are prototype quantities of hydraulic conductivity, hydraulic head, specific storage, flow velocity, horizontal coordinate, and time, respectively; After arrangement, we get: ; ; Let the combination of each ratio satisfy the following formula: ; ; By selecting different ratios, the groundwater seepage law under different rainfall durations can be simulated; When the water content in the soil layer changes, the value of the hydraulic conductivity K in the above formula will also change. However, in the existing technology, there is no sensing device that can directly measure the value of the hydraulic conductivity K . In this embodiment, the calculation method of the hydraulic conductivity K is to accurately detect the water content by measuring the soil dielectric constant of the soil layer, and then use the corresponding relationship between the water content of the soil itself and the hydraulic conductivity K to obtain the change state of the value of the hydraulic conductivity K ; Fitting the hydraulic conductivity K with the water content as a variable, the relationship formula is as follows:

[0037] Among them, K θ The hydraulic conductivity of the soil when the water content is θ ; ks is the hydraulic conductivity of the soil in a fully saturated state; θ is the volumetric water content; θs is the volumetric water content of the soil in a fully saturated state; θ r is the residual water content, which is the critical point of permeability failure. When it is lower than θ r , the soil is impermeable; m is the non-linear index; The relationship formula between the dielectric constant and the water content θ is:

[0038] Among them, is the dielectric constant of the soil layer, which is measured by the buried dielectric constant sensor during the test; are all empirical coefficients, , , , . For example, let α K = 1, α S = 1, α x = 1:20, α H = 1:20; Substitute into the above formula and calculate to get: α t = 1:400, α v = 1; When the model ratio is determined, the time ratio α t is a definite number. According to the above example, when simulating 10 days of continuous rainfall, the test time required is: T = 10 * 24 * 3600 / 400 s = 2160 s = 36 min.

[0039] At the beginning of rainfall, the soil mass is in an unsaturated state. As the rainfall infiltrates into the soil mass, the water content of the soil mass gradually increases, and the permeability coefficient changes accordingly. At this time, only through the dielectric constant sensor 7 in the soil mass, the change of water content can be quickly measured, and the change of the permeability coefficient K can be calculated. The drainage data of the pressure-limiting drain pipe 3 can be used to study the groundwater seepage law under the active anti-floating measures when the water content changes. When the rainfall is large, the soil mass gradually enters the saturated state, and the rainfall will be discharged in two ways: infiltration and surface runoff.

[0040] In summary, the active anti-floating drainage model test device and test method considering saturation changes can demonstrate the drainage conditions of active anti-floating measures and the seepage law of soil during the transition process of soil from unsaturated to saturated under different rainfall and different stratum conditions. The test method dynamically adjusts the rainfall intensity, replaces the soil layer structure with different permeability characteristics, adjusts the spacing and elevation arrangement of the pressure-limiting drain pipes 3, and combines with the dielectric constant sensor 7 to monitor the saturation distribution of the soil in real time, systematically revealing the groundwater seepage response mechanism of active anti-floating measures under the coupling action of rainfall and soil structure. During the test process, pore pressure sensors 6 and multiple dielectric constant sensors 7 are buried in layers at the key sections of the soil layer of the soil mass to synchronously collect dynamic data of volumetric water content-saturation, pore water pressure evolution curves, and the water discharge from the pressure-limiting drain pipes 3. Through multi-source data fusion, analyze the non-uniform distribution law of saturation in different soil layer structures during rainfall infiltration and drainage processes and its influence on the seepage path, accurately simulate the seepage behavior in the groundwater unsaturated-saturated transition zone, fill the gap in the existing test devices of this type for soil saturation change factors, and provide a scientific basis and data support for the optimized application of active anti-floating measures under different saturation conditions.

[0041] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, terms such as "installation", "provided with", "sheathed / connected", "connection", etc. should be understood in a broad sense. For example, "connection" 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 directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0042] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An active anti-floating drainage model test device considering saturation change, characterized in that It includes: a boundary model box and a building model box fixedly arranged inside the boundary model box; A plurality of pore pressure sensors and a plurality of dielectric constant sensors are buried inside the boundary model box; A pressure-limiting drainage pipe for simulating the active anti-floating device in an actual building is arranged at the bottom of the building model box.

2. The active anti-floating drainage model test device considering saturation change according to claim 1, characterized in that A plurality of bolts are arranged 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.

3. The active anti-floating drainage model test device considering saturation change according to claim 1, characterized in that The number of the pressure-limiting drainage pipes is multiple, and the lengths and end positions of the multiple pressure-limiting drainage pipes are adjustable.

4. The active anti-floating drainage model test device considering saturation change according to claim 1, characterized in that, It further includes a water head control device, and the water head control device includes a drainage groove arranged on the periphery of the top of the boundary model box, and the top height of the drainage groove is flush with the top of the boundary model box; the drainage groove is connected to a second water collection tank through a pipeline, and a second flowmeter is installed on the pipeline.

5. The active anti-floating drainage model test device considering saturation change according to claim 1, characterized in that, The inside of the boundary model box is used for filling and laying 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.

6. The active anti-floating drainage model test device considering saturation change according to claim 5, characterized in that It further includes a rainfall simulation device, and the rainfall simulation device includes a water delivery pipeline, a first flowmeter, a water pump, a first water collection tank and a telescopic support; The water delivery pipeline is arranged on the top of the boundary model box through the telescopic support, the water delivery pipeline is communicated with the first water collection tank through a hose, and the first flowmeter and the water pump are arranged on the hose; a plurality of nozzles are arranged on the water delivery pipeline, and the water spraying ranges of the plurality of nozzles cover the surface of the simulated soil layer structure.

7. The test method of the active anti-floating drainage model test device considering saturation change according to any one of claims 1 to 6, characterized in that, It includes the following steps: S1. Lay the soil layer in layers inside the boundary model box, and install a plurality of pore pressure sensors and a plurality of dielectric constant sensors at different height positions of the soil layer; S2. Install and fix the building model box inside the boundary model box through a plurality of bolts, and the bottom of the building model box is in contact with the upper surface of the soil layer; S3. Install a plurality of pressure-limiting drainage pipes inside the building model box according to preset conditions, and adjust the lengths and end positions of the plurality of pressure-limiting drainage pipes; S4. Install the drainage groove on the periphery of the top of the boundary model box; S5. Install the rainfall simulation device, and adjust the height of the telescopic support so that the water spraying ranges of the plurality of nozzles cover the upper surface of the simulated soil layer; S6. Conduct multiple groups of tests by changing the rainfall conditions, soil layer structure conditions and the layout modes of the plurality of pressure-limiting drainage pipes; after each group of tests is completed, collect the monitoring data of the pore pressure sensors, dielectric constant sensors, second flowmeter and first flowmeter, and obtain the groundwater seepage law of the active anti-floating device under different rainfall conditions, different soil layer structure conditions, different layout modes of the plurality of pressure-limiting drainage pipes and the change of soil saturation.

8. The test method of the active anti-floating drainage model test device considering saturation change according to claim 7, characterized in that, In step S1, the dielectric constant sensors and the pore pressure sensors are buried in layers; during the process of laying the soil layer, the soil samples are cut layer by layer, and the permeability test and the water characteristic curve test are carried out to ensure that the actual permeability coefficient and saturation evolution law of the soil body are consistent with the design parameters; by laying different soil layers and initial saturation distributions, multiple groups of comparative experiments are repeatedly carried out to analyze the influence of the non-uniform saturation field of the soil body on the seepage path.

9. The test method of the active anti-floating drainage model test device considering saturation change according to claim 7, characterized in that In step S6, the soil layer structure and the layout method of multiple pressure-limiting drainage pipes remain unchanged, and the rainfall conditions are changed. Based on the monitoring data of the pore pressure sensor, the dielectric constant sensor, the second flowmeter, and the first flowmeter, the groundwater seepage law of the active anti-floating device under different rainfall conditions and different soil saturation changes of the soil layer can be obtained. With the rainfall conditions and the layout method of multiple pressure-limiting drainage pipes remaining unchanged, the soil layer structure is changed. Based on the monitoring data of the pore pressure sensor, the dielectric constant sensor, the second flowmeter, and the first flowmeter, the groundwater seepage law of the active anti-floating device under different soil layer structure conditions and different soil saturation changes of the soil layer can be obtained. With the rainfall conditions and the soil layer conditions remaining unchanged, the layout method of multiple pressure-limiting drainage pipes is changed. Based on the monitoring data of the pore pressure sensor, the dielectric constant sensor, the second flowmeter, and the first flowmeter, the groundwater seepage law of the active anti-floating device under different layout methods of multiple pressure-limiting drainage pipes and different soil saturation changes of the soil layer can be obtained.

10. The test method of the active anti-floating drainage model test device considering saturation change according to claim 9, characterized in that, In step S6, the rainfall conditions include rainfall amount and rainfall time. The simulation method of the rainfall time is as follows: In a homogeneous and isotropic medium, the one-dimensional confined flow equations for the cross-section are: ； ； wherein, K is the permeability coefficient, H is the hydraulic head, S s is the storage coefficient, v is the flow velocity, t is the time, x is the coordinate in the horizontal direction; Introduce a set of dimensionless ratios α H 、 α S 、 α K 、 α x 、 α t 、 α v : ； ； ； ； ； ； Among them, K m 、 H m 、 S s,m 、 v m 、 x m 、 t m are respectively the model quantities of the permeability coefficient, water head, storage rate, flow velocity, horizontal coordinate, and time, K 、 H 、 S s 、 v 、 x 、 t are respectively the prototype quantities of the permeability coefficient, water head, storage rate, flow velocity, horizontal coordinate, and time; After arrangement, we get: ； ； Let the combination of each ratio satisfy the following formula: ； ； By selecting different ratios, the groundwater seepage law under different rainfall durations can be simulated. When the water content in the soil layer changes, the permeability coefficient in the above formula K will also change; the calculation method of the permeability coefficient K is to accurately detect the water content by measuring the soil dielectric constant of the soil layer, and then use the corresponding relationship between the water content of the soil body itself and the permeability coefficient K to obtain the change state of the value of the permeability coefficient K ; Fitting the permeability coefficient with water content as a variable K , and the relationship is as follows: Among them, K θ the permeability coefficient of the soil at the water content θ ; 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 it is fully saturated; θ r is the residual water content, which is the critical point of permeability failure. Below θ r the soil is impermeable; m is the non-linear exponent; Dielectric Constant and Water Content θ The relational formula is as follows: Among them, is the dielectric constant of the soil layer, which is measured by the buried dielectric constant sensor during the test; are all empirical coefficients, , , , .

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