A test device for water migration in a slope model under freeze-thaw cycles

Abstract

This invention discloses a slope model moisture migration testing device under freeze-thaw cycles, comprising: a model box containing a soil-rock slope model, with the bottom of the model connected to an automatic water replenishment device. The automatic water replenishment device includes a sample water replenishment tank, a pressure balance pipe, and a Mariotte bottle. A fluorescent tracer is added to the sample water replenishment tank to allow for direct observation of the moisture migration process within the slope. The freeze-thaw cycle system of this device includes an upper cold bath plate, a cold bath device, a lower ambient temperature plate, an ambient temperature water pump, and connecting pipelines to simulate the freeze-thaw cycle of a slope caused by actual atmospheric environmental changes. The device includes a laser displacement meter, a temperature sensor, a data acquisition instrument, a computer, an ultraviolet lamp, and a digital camera to collect data on physical quantities such as displacement and temperature during the deformation process of the slope model, providing a quantitative analysis basis for the required research. By simulating the temperature rise and fall effects of the atmospheric environment on the slope model through the freeze-thaw cycle system, the deformation and internal moisture migration process of the slope model under freeze-thaw cycles are observed. This provides a basis for the mechanism research and prediction and early warning of geological disasters on slopes in cold regions.

Description

Technical Field

[0001] This invention belongs to the field of geotechnical engineering testing and engineering application technology, and specifically relates to a device for testing the water migration of slope models under freeze-thaw cycles. Background Technology

[0002] In permafrost regions, influenced by ambient temperature, surface soil and rock media undergo repeated freezing and thawing, a process known as freeze-thaw cycles. At lower temperatures, water in the soil and rock media freezes, its volume expanding and altering the microstructure of the pores, while moisture migrates towards the frozen zone. At higher temperatures, the ice melts, and the moisture redistributes within the soil and rock media. This freeze-thaw cycle causes moisture migration within the soil and rock media, altering its internal structure and reducing its mechanical properties, thus affecting the safety of geotechnical engineering in cold regions. Furthermore, the pattern of moisture migration within the soil and rock media changes depending on the number of freeze-thaw cycles.

[0003] CN105092578B discloses a device and experimental method for tracking the water migration process in frozen soil. The device includes a soil sample tank, an upper cold bath plate, and a lower cold bath tank. The upper and lower cold bath plates are used to unidirectionally cool the soil. The water migration process in frozen soil is observed directly by adding a fluorescent agent to the soil sample. However, this device and method do not consider the influence of freeze-thaw cycles on the internal water migration of the soil and rock media. Furthermore, the sample size is relatively small, making it unsuitable for slope models scaled down from actual slope engineering projects. It does not design a slope slip zone, and the device boundaries constrain the free deformation of the internal soil sample, thus failing to recreate the slope instability process under freeze-thaw cycles. Summary of the Invention

[0004] The technical problem this invention aims to solve is the observation of temperature field distribution, deformation, and moisture migration in a soil and rock slope model under freeze-thaw cycles. It provides a device for testing moisture migration in a slope model under freeze-thaw cycles. This device simulates actual groundwater recharge, enabling low-temperature moisture migration testing in soil and rock media. The device has a simple and clear overall structure, low cost, and allows for direct observation of the deformation and moisture migration processes of the slope model under freeze-thaw cycles, providing strong visibility.

[0005] To address the problems in the existing technology, the technical solution adopted by this invention is as follows:

[0006] A test device for water migration of a slope model under freeze-thaw cycles includes a model box, an ultraviolet lamp and a digital camera. The internal space of the model box is used to place the slope model sample, a steel frame and an upper cold bath plate. Several temperature sensors are embedded inside the slope model sample. The temperature sensors are all connected to a data acquisition instrument, which is connected to a computer.

[0007] The model box is a closed model with a lid, creating a closed simulation environment;

[0008] The slope model specimen is placed close to the inner wall of the model box on the top side, and a space is left between the slope foot side and the inner wall of the model box. The length of the space is not less than half the height of the slope model to allow the slope to deform freely.

[0009] Inside the model box, a steel frame is erected at a position higher than the top of the slope model sample, and several laser displacement gauges are installed on the side of the steel frame facing the inside of the model box.

[0010] The model box is equipped with an upper cold bath plate above the lid and steel frame. The upper cold bath plate is equipped with a coolant copper pipe. The two ends of the coolant copper pipe are the coolant inlet and the coolant outlet, respectively. The coolant inlet is connected to the condensate input pipe, and the coolant outlet is connected to the condensate output pipe. The upper cold bath plate is connected to the cold bath device through the condensate input pipe and the condensate output pipe. The other end of the condensate input pipe is connected to the outlet of the cold bath device, and the other end of the condensate output pipe is connected to the inlet of the cold bath device.

[0011] A lower ambient temperature plate is installed below the model box. A ambient temperature water copper pipe is installed inside the lower ambient temperature plate. The two ends of the ambient temperature water copper pipe are the ambient temperature water inlet and the ambient temperature water outlet. The ambient temperature water inlet is connected to the ambient temperature water input pipe, and the ambient temperature water outlet is connected to the ambient temperature water output pipe. The lower ambient temperature plate is connected to the ambient temperature water pump through the ambient temperature water input pipe and the ambient temperature water output pipe.

[0012] The bottom of the model box is equipped with a sample water replenishment tank. One side of the sample water replenishment tank is connected to an air pressure balance pipe with a hose to balance the air pressure in the sample water replenishment tank, so that the water in the Mario bottle can flow into the sample water replenishment tank. The other side is connected to the Mario bottle with a water injection hose, and water is injected into the sample water replenishment tank by utilizing the principle of communicating vessels.

[0013] As an improvement, the model box has holes to facilitate the passage of data transmission lines and condensate / room temperature water input / output pipes. The model box is made of highly transparent acrylic glass.

[0014] As an improvement, in the process of simulating slope freezing caused by atmospheric cooling, the upper cold bath plate provides negative temperature to the cold end and the lower normal temperature plate provides positive temperature to the warm end, forming a unidirectional freezing field from top to bottom; in the process of simulating slope melting caused by atmospheric heating, the upper cold bath plate is connected to a normal temperature water pump, and the upper part of the model is converted to the warm end providing positive temperature.

[0015] As an improvement, the ambient temperature water pump has a temperature control function, and the temperature setting range is 0~30℃, which can simulate the temperature of the actual underground soil and rock media in different seasons.

[0016] As an improvement, the liquid stored inside the sample replenishment tank contains a fluorescent tracer, and under freeze-thaw cycles, the water containing the fluorescent tracer will migrate into the interior of the slope model sample. Beneficial effects

[0017] Compared with existing technologies, this invention provides a water migration testing device for slope models under freeze-thaw cycles. This device simulates the freeze-thaw cycles of model samples caused by atmospheric temperature fluctuations at a laboratory scale, while simultaneously simulating real groundwater recharge, providing a basis for research on the mechanisms of geological disasters in cold regions. The device has a clear overall structure, low cost, and can simulate the freeze-thaw cycles of soil and rock media caused by actual atmospheric temperature fluctuations. The temperatures of the cold and warm ends are controllable and can be set according to the actual slope engineering problems being simulated. The temperature data acquisition function of this device can reflect the temperature field within the simulated slope, which can be used for corresponding theoretical and numerical simulation studies. The device monitors the deformation of the slope model under freeze-thaw cycles, enabling direct observation of the deformation and water migration processes, providing strong visibility. Combined with laser displacement gauges and temperature sensors, it allows for quantitative research on slope problems under freeze-thaw cycles. The operation is simple, and the data reliability is high. This device provides a reference for actual slope engineering design and safety protection. Attached Figure Description

[0018] Figure 1 A schematic diagram of the overall structure of the water migration device in a slope model under freeze-thaw cycles for testing.

[0019] Figure 2 This is a schematic diagram of the upper cooling bath plate.

[0020] Figure 3 This is a schematic diagram of the structure of the lower room temperature plate.

[0021] Among them, 1—model box, 2—upper cold bath plate, 2-1—cooling fluid inlet, 2-2—cooling fluid copper pipe, 2-3—cooling fluid outlet, 3—lower ambient temperature plate, 3-1—ambient temperature water inlet, 3-2—ambient temperature water copper pipe, 3-3—ambient temperature water outlet, 4—slope model specimen, 5—steel frame, 6—pressure balance pipe, 7—Marriott bottle, 8—sample water replenishment tank, 9—laser displacement gauge, 10—temperature sensor, 11—data acquisition instrument, 12—computer, 13—cold bath device, 14—condensate input pipe, 15—condensate output pipe, 16—ambient temperature water pump, 17—ambient temperature water input pipe, 18—ambient temperature water output pipe, 19—ultraviolet lamp, 20—digital camera. Detailed Implementation

[0022] The following embodiments are provided to enable those skilled in the art to more fully understand the present invention, but do not limit the invention in any way. Example 1

[0023] A device for testing water migration in a slope model under freeze-thaw cycles includes a model box, an ultraviolet lamp, and a digital camera. The interior space of the model box is used to place the slope model sample, a steel frame, and an upper cold bath plate. Several temperature sensors are embedded inside the slope model sample, and all temperature sensors are connected to a data acquisition instrument, which is connected to a computer. The data acquisition instrument transmits the collected temperatures at different locations of the slope model under different freeze-thaw cycle conditions to the computer to quantitatively analyze the temperature field distribution inside the slope under different freeze-thaw cycle conditions.

[0024] The model box is a closed model with a lid, creating a closed simulation environment;

[0025] The slope model specimen is placed close to the inner wall of the model box on the top side of the slope, and a space is left between the bottom side of the slope and the inner wall of the model box. The length of the space is not less than half the height of the slope model, so as to allow the slope to deform freely.

[0026] Inside the model box, a steel frame is erected at a position higher than the top of the slope model sample. Several laser displacement gauges are installed on the side of the steel frame facing the inside of the model box. The laser displacement gauges are used to perform quantitative analysis of the slope deformation. The model box is made of transparent material so that the slope deformation during the test can be directly observed.

[0027] The model box is equipped with an upper cold bath plate above the lid and steel frame. The upper cold bath plate is equipped with a coolant copper pipe. The two ends of the coolant copper pipe are the coolant inlet and the coolant outlet, respectively. The coolant inlet is connected to the condensate input pipe, and the coolant outlet is connected to the condensate output pipe. The upper cold bath plate is connected to the cold bath device through the condensate input pipe and the condensate output pipe. The other end of the condensate input pipe is connected to the outlet of the cold bath device, and the other end of the condensate output pipe is connected to the inlet of the cold bath device.

[0028] A lower ambient temperature plate is installed below the model box. A ambient temperature water copper pipe is installed inside the lower ambient temperature plate. The two ends of the ambient temperature water copper pipe are the ambient temperature water inlet and the ambient temperature water outlet. The ambient temperature water inlet is connected to the ambient temperature water input pipe, and the ambient temperature water outlet is connected to the ambient temperature water output pipe. The lower ambient temperature plate is connected to the ambient temperature water pump through the ambient temperature water input pipe and the ambient temperature water output pipe.

[0029] The bottom of the model box is equipped with a sample water replenishment tank. One side of the tank is connected to a pressure balancing pipe via a hose to balance the air pressure inside the tank, allowing water from the Mario bottle to flow into the tank. The other side is connected to the Mario bottle via a water injection hose, utilizing the principle of communicating vessels to inject water into the tank, achieving automatic and continuous water replenishment for the slope model sample. The sample water replenishment tank simulates the groundwater recharge process of an actual slope, ensuring sufficient water volume inside the sample during freeze-thaw cycles to facilitate water migration.

[0030] The model box has holes to facilitate the passage of data transmission lines and condensate / room temperature water input / output pipes. The model box is made of highly transparent acrylic glass.

[0031] In simulating slope freezing caused by atmospheric cooling, the upper cold bath plate provides negative temperature to the cold end and the lower ambient temperature plate provides positive temperature to the warm end, forming a unidirectional freezing field from top to bottom; in simulating slope melting caused by atmospheric warming, the upper cold bath plate is connected to an ambient temperature water pump, and the upper part of the model is converted to the warm end providing positive temperature.

[0032] The ambient temperature water pump has a temperature control function, and the temperature setting range is 0~30℃, which can simulate the temperature of the actual underground soil and rock media in different seasons.

[0033] The liquid stored inside the sample replenishment tank contains a fluorescent tracer. Under freeze-thaw cycles, the water containing the fluorescent tracer will migrate into the slope model sample. Since water migration inside the slope model is a microscopic physical process that is difficult to observe directly, the bottom of the slope model sample is connected to the sample replenishment tank, and a fluorescent tracer is added to the tank. A Mario bottle is used to automatically replenish the water in the slope model sample, maintaining a constant water level in the tank. Ultraviolet light illumination and digital imaging methods are used to analyze water migration inside the slope model under different freeze-thaw cycle conditions.

[0034] The specific steps are as follows:

[0035] 1) Warm end arrangement

[0036] First, place a room temperature plate at the bottom of the model box. Room temperature water copper pipes are laid inside the room temperature plate. The two ends of the room temperature water copper pipes are the room temperature water inlet and the room temperature water outlet. The room temperature water inlet is connected to the room temperature water input pipe, and the room temperature water outlet is connected to the room temperature water output pipe. The room temperature plate is connected to the room temperature water pump through the room temperature water input pipe and the room temperature water output pipe.

[0037] Place a sample water replenishment tank on a room temperature plate. Connect one side of the tank to a pressure balance tube with a hose, and the other side to a Mariotte bottle with a water injection hose. Add fluorescent tracer to the sample water replenishment tank.

[0038] 2) Sample loading and sensor setup

[0039] Based on the required moisture content and density, a slope model specimen is constructed inside a model box using a layered filling method. The number of layers should be no less than three. The top of the slope is flush with the model box, while space is reserved for slope sliding on the toe side. Temperature sensors are embedded when the filling reaches the layer height or the simulated observation point height. The sensor wiring is connected to an external data acquisition instrument through a small hole on the model box, which is then connected to a computer. The entire slope model is then sealed and cured for one day.

[0040] A steel frame is erected inside the model box at a position higher than the top of the slope model specimen. Several laser displacement gauges are installed on the side of the steel frame facing inwards from the model box. Ultraviolet lights and digital cameras are installed outside the model box.

[0041] 3) Cold end arrangement

[0042] A cooling bath plate is placed on top of the model box. The cooling bath plate is equipped with copper pipes for refrigerant. The two ends of the copper pipes are the refrigerant inlet and the refrigerant outlet, respectively. The cooling bath plate is connected to the cooling bath device through a condensate inlet pipe and a condensate outlet pipe.

[0043] 4) Freeze-thaw cycle loading

[0044] Set the cold end temperature of the cold bath device and activate the upper cold bath plate to freeze the sample. Turn on the ambient temperature water pump to achieve a constant warm end at the bottom of the sample. When the freezing time reaches the set freeze-thaw cycle requirement, stop the cold bath, connect the upper cold bath plate to the ambient temperature water pump, and begin the sample thawing process. When the thawing time reaches the required value, turn off the ambient temperature water pump. Repeat this cycle to simulate the freeze-thaw cycle of the slope model, recording slope deformation and temperature data in a timely manner. Use a digital camera to record the movement of the entire slope model and trace the internal moisture migration and ice crystal formation processes.

[0045] Based on the required freeze-thaw cycle period, the temperature field of the model specimen is periodically changed by the upper cold bath plate and the lower ambient temperature plate to simulate atmospheric temperature rise and fall. When simulating atmospheric cooling, the upper cold bath plate is connected to the cold bath device, and the lower ambient temperature plate is connected to an ambient temperature water pump, creating a temperature field where the upper end of the specimen is cold and the lower end is warm, causing unidirectional freezing of the model specimen. When simulating atmospheric warming, both the upper cold bath plate and the lower ambient temperature plate are connected to the ambient temperature water pump, creating a constant temperature field, allowing the model specimen to fully thaw. Based on the experimental results, the mechanism of slope instability caused by freeze-thaw cycles is studied, and prediction and early warning analysis are conducted.

Claims

1. A moisture migration test device for a slope model under freeze-thaw cycles, comprising a model box (1), an ultraviolet lamp (19) and a digital camera (20), characterized in that, The internal space of the model box (1) is used to place the slope model specimen (4), steel frame (5), and upper cold bath plate (2). A number of temperature sensors (10) are buried inside the slope model specimen (4), and the temperature sensors (10) are all connected to a data collector (11), and the data collector (11) is connected to a computer (12). The model box (1) is a closed model with a lid to create a closed simulation environment. One side of the top of the slope model specimen (4) is placed closely against the inner wall of the model box, and there is a space between the other side of the bottom of the slope and the inner wall of the model box. The length of the space is not less than half of the height of the slope model specimen to allow the slope to deform freely. Inside the model box (1) and at a position higher than the top of the slope model specimen, a steel frame (5) is erected, and a number of laser displacement gauges (9) are installed on the side of the steel frame (5) facing the inside of the model box (1). Above the steel frame (5) and on the lid of the model box (1), there is an upper cold bath plate (2). Inside the upper cold bath plate (2), there are refrigerant copper tubes (2-2). The two ends of the refrigerant copper tubes (2-2) are respectively a refrigerant inlet end (2-1) and a refrigerant outlet end (2-3). The refrigerant inlet end (2-1) is connected to a condensate input pipe (14), and the refrigerant outlet end (2-3) is connected to a condensate output pipe (15). The upper cold bath plate (2) is connected to a cold bath device (13) through the condensate input pipe (14) and the condensate output pipe (15). The other end of the condensate input pipe (14) is connected to the liquid outlet of the cold bath device, and the other end of the condensate output pipe (15) is connected to the liquid inlet of the cold bath device. Below the model box (1), there is a lower normal temperature plate (3). Inside the lower normal temperature plate (3), there are normal temperature water copper tubes (3-2). The two ends of the normal temperature water copper tubes (3-2) are respectively a normal temperature water inlet end (3-1) and a normal temperature water outlet end (3-3). The normal temperature water inlet end (3-1) is connected to a normal temperature water input pipe (17), and the normal temperature water outlet end (3-3) is connected to a normal temperature water output pipe (18). The lower normal temperature plate (3) is connected to a normal temperature water pump (16) through the normal temperature water input pipe (17) and the normal temperature water output pipe (18). At the bottom of the model box (1), there is a specimen water replenishment tank (8). One side of the specimen water replenishment tank (8) is connected to a pressure balance pipe (6) with a hose, and the other side is connected to a Mariotte bottle (7) with a water injection hose to balance the air pressure in the specimen water replenishment tank, so that the water in the Mariotte bottle can flow into the specimen water replenishment tank, and water is injected into the specimen water replenishment tank using the principle of communicating vessels. Among them, during the simulation of the freezing process of the slope caused by the cooling of the atmospheric environment, the upper cold bath plate (2) provides negative temperature for the cold end, and the lower normal temperature plate (3) provides positive temperature for the warm end, forming a one-way freezing field from top to bottom; during the simulation of the melting process of the slope caused by the warming of the atmospheric environment, the upper cold bath plate (2) is connected to the normal temperature water pump (16), then the upper part of the model is converted to provide positive temperature for the warm end.

2. The moisture migration test device for the slope model under freeze-thaw cycles according to claim 1, wherein The model box (1) has holes to facilitate the connection of pipelines and data transmission lines to be inserted into the box. The material of the model box (1) is high-transparency organic glass.

3. The moisture migration test device for the slope model under freeze-thaw cycles according to claim 1, wherein The normal temperature water pump (16) has a temperature control function, and the temperature setting range is 0~30°C, which can simulate the temperature of the actual underground rock and soil medium in each season.

4. The moisture migration test device for the slope model under freeze-thaw cycles according to claim 1, wherein The liquid stored inside the sample water replenishing tank (8) contains a fluorescent tracer. Under the action of freeze-thaw cycles, the water containing the fluorescent tracer will migrate into the slope model sample.

Images