Simulation Test Apparatus and Method for Glacial Deposits Seepage and Particle Migration under Rainfall Conditions

Abstract

This invention relates to the field of mine geological disaster control and geotechnical engineering testing technology, and particularly to a device and method for simulating and testing the seepage and particle migration of glacial till under rainfall conditions. The device includes a rainfall simulation mechanism, a glacial till seepage simulation mechanism, a seepage monitoring system, and a migration and seepage monitoring system. The glacial till seepage simulation mechanism includes a cylinder, and the monitoring end of the seepage monitoring system is located inside the cylinder. By setting up a rainfall simulation mechanism and a cylinder, and placing the monitoring end of the seepage monitoring system inside the cylinder, this invention allows the seepage monitoring system to monitor the seepage and moisture content changes of glacial till samples at different depths in real time. The migration and seepage monitoring system collects infiltrated water and migrating fine particles, enabling researchers to determine the rainwater infiltration situation of this type of glacial till sample and the migration pattern of fine particles under infiltration conditions based on the amount of water and fine particles collected by the migration and seepage monitoring system.

Description

Technical Field

[0001] This invention relates to the field of mine geological disaster control and geotechnical engineering testing technology, and in particular to a device and method for simulating the seepage and particle migration of glacial till under rainfall conditions. Background Technology

[0002] In mine subsidence areas, surface water easily accumulates and infiltrates under rainfall. The overburden layer in these areas is often glacial till, a typical mixture of coarse and fine particles with a complex pore structure. During rainfall infiltration, the hydrodynamic forces of the seepage flow drive the migration and deposition of fine particles, gradually forming blockages at the pore throats. This alters the effective seepage channels in the medium, affects seepage parameters, and significantly increases the risk of infiltration and sudden surges of the mud-water mixture. Accurately simulating and revealing the coupling mechanism of "seepage-fine particle migration" within glacial till under rainfall is of great significance for the assessment and prevention of geological hazards in subsidence areas.

[0003] Currently, existing devices are insufficient for systematic research on the coupled process of "seepage-fine particle migration". There is an urgent need to develop an experimental device and method that can achieve uniform rainfall, stratified dynamic monitoring, and graded collection of fine particles. Summary of the Invention

[0004] To overcome the shortcomings mentioned in the background art, this application provides a device and method for simulating the seepage and particle migration of glacial till under rainfall conditions.

[0005] A simulation testing device for glacial moraine seepage and particle migration under rainfall conditions includes a rainfall simulation mechanism for simulating artificial rainfall, a glacial moraine seepage simulation mechanism for filling soil samples, a seepage monitoring system for monitoring glacial moraine seepage, and a migration and seepage monitoring system for monitoring fine particle migration and water seepage. The glacial moraine seepage simulation mechanism includes a cylinder with a glacial moraine filling area inside. The top of the cylinder has an inlet for receiving rainfall, and the bottom of the cylinder has an outlet. The monitoring end of the seepage monitoring system is located inside the cylinder, and the migration and seepage monitoring system is located below the outlet of the cylinder.

[0006] As one embodiment, the rainfall simulation mechanism includes a nozzle and a water supply pipe connected to the nozzle. The nozzle is located above the inlet of the cylinder. The water supply pipe is connected to a water pump. The inlet of the water pump is connected to a water tank through a pipe. The water supply pipe is equipped with a regulating valve for adjusting the water volume.

[0007] As one embodiment, a rainfall distribution plate for uniformly dispersing the water sprayed from the nozzle is installed below the nozzle, and the rainfall distribution plate is provided with uniformly distributed micropores.

[0008] As one embodiment, an mounting plate is provided above the cylinder, the cylinder is mounted on the base, the nozzle and the rainfall distribution plate are both mounted on the mounting plate, an annular plate is installed at the bottom of the cylinder, a through hole is provided in the middle of the annular plate, the diameter of the through hole of the annular plate is smaller than the inner diameter of the cylinder, and a migration and seepage monitoring system is provided below the through hole of the annular plate.

[0009] In one embodiment, a mounting plate is provided above the cylinder, the cylinder is mounted on a base, the nozzle and the rainfall distribution plate are both mounted on the mounting plate, a filter screen is provided at the bottom outlet of the cylinder, the migration and seepage monitoring system is located below the filter screen, the diameter of the filter screen is equal to the inner diameter of the cylinder, the inner diameter of the inlet of the migration and seepage monitoring system is smaller than the inner diameter of the cylinder, and the axis of the inlet of the migration and seepage monitoring system coincides with the axis of the cylinder.

[0010] As one embodiment, the seepage monitoring system includes a data acquisition instrument and a moisture sensor. Multiple moisture sensors are installed at different positions along the axial direction of the cylinder. At least one moisture sensor is provided for each sample layer in the cylinder. All moisture sensors are electrically connected to the data acquisition instrument. The outer wall of the cylinder is provided with a scale for measuring the water accumulation height.

[0011] As one embodiment, the migration and seepage monitoring system includes a particle trapping device for collecting particles and an effluent collection device for collecting seepage water, the effluent collection device being located below the particle trapping device.

[0012] In one embodiment, the particle collection device includes an upper filter screen, a middle filter screen, and a lower filter screen for graded collection of fine particles. The permeate collection device is located below the lower filter screen. The upper filter screen, the middle filter screen, and the lower filter screen are arranged in a top-to-bottom order, with the pore size of the three screens decreasing sequentially.

[0013] A simulation test method for glacial till seepage and particle migration under rainfall conditions, using any of the simulation test devices described above, includes the following steps: S1: The glacial deposit sample is loaded into the cylinder in layers, and each layer of sample is compacted after loading. S2: Activate the seepage monitoring system to record the moisture content of the sample in real time; S3: Artificial rainfall is simulated by introducing rainfall into the glacial till seepage simulation mechanism; S4: Wait for fine particles and infiltration water to enter the migration and seepage monitoring system, shut down the rainfall simulation mechanism, and record the amount of particles and infiltration water on the migration and seepage monitoring system.

[0014] As one implementation method, after the seepage monitoring system is turned on, the water accumulation height on the sample surface is recorded in real time to obtain the relationship between the water accumulation height and the migration amount of fine particles and the water seepage flow rate.

[0015] The beneficial effects of this application are: This invention incorporates a rainfall simulation mechanism and a cylindrical body. The monitoring end of the seepage monitoring system is located inside the cylindrical body, while a migration and seepage monitoring system is installed below the cylindrical body. This allows the seepage monitoring system to monitor the seepage and moisture content changes of glacial till samples at different depths in real time. The migration and seepage monitoring system collects infiltrated water and migrating fine particles, enabling researchers to determine the rainwater infiltration status of the glacial till sample and the migration pattern of fine particles under infiltration conditions based on the amount of water and fine particles collected by the migration and seepage monitoring system.

[0016] Other technical solutions of the present invention can also achieve the following technical effects: By installing a rainfall distribution plate below the nozzle, which has uniformly distributed micropores, the water sprayed from the nozzle can be evenly dispersed, reducing the impact of localized concentrated scouring, improving the consistency of the rainfall boundary, thereby enhancing the realism of the simulated rainfall, ensuring the rigor of the experiment, and obtaining the most realistic experimental data possible.

[0017] By installing an annular plate at the bottom of the cylinder with a through hole in the middle, fine particles near the center of the cylinder can migrate downwards, while preventing fine particles located at the edge of the cylinder from passing through the through hole. This minimizes the impact of the cylinder's circumferential inner wall on the migration of fine particles when in contact with the glacial deposit sample. As a result, the migration and seepage monitoring system only collects fine particles migrating from the glacial deposit sample in the middle of the cylinder, thereby reducing experimental errors and improving the accuracy of experimental data.

[0018] By setting up multiple moisture sensors, each of which is electrically connected to the data acquisition instrument via a signal line, based on the stratified response data obtained from multiple moisture sensors, it is possible not only to construct the moisture content-time response curve and moisture content-depth distribution curve inside the sample, but also to obtain the dynamic evolution results of the infiltration process inside the sample through threshold identification, differential operation, interpolation fitting and interlayer comparison, and further obtain the characteristics of seepage front advancement, local water retention and stratified infiltration.

[0019] By setting up an upper, middle, and lower filter screen, with the pore size decreasing from top to bottom, the three filter screens can classify, intercept, and collect fine particles, enabling statistical analysis of the migration amount and particle size composition of fine particles. By weighing and sieving the particles intercepted by each screen, coupled response data between rainfall infiltration, seepage evolution, and fine particle migration can be obtained. Attached Figure Description

[0020] Figure 1 This is a three-dimensional structural schematic diagram of the simulation test device for glacial till seepage and particle migration under rainfall conditions disclosed in the embodiments of the present invention; Figure 2 This is a schematic diagram showing the positional relationship between the sprinkler head and the rainfall distribution plate disclosed in the embodiments of the present invention; Figure 3 This is a top view of the rainfall distribution plate disclosed in the embodiments of the present invention; Figure 4 This is a schematic diagram showing the positional relationship between the upper filter, middle filter, and lower filter as disclosed in the embodiments of the present invention.

[0021] In the attached diagram, the following are the reference numerals: 1. Rainfall simulation mechanism; 101. Sprinkler head; 102. Water supply pipe; 103. Water pump; 104. Water tank; 105. Regulating valve; 106. Rainfall distribution plate; 2. Moraine seepage simulation mechanism; 201. Cylinder; 202. Mounting plate; 203. Annular plate; 3. Seepage monitoring system; 301. Data acquisition instrument; 302. Moisture sensor; 4. Migration and seepage monitoring system; 401. Particle collection device; 4011. Upper filter screen; 4012. Middle filter screen; 4013. Lower filter screen; 402. Seepage collection device. Detailed Implementation

[0022] To make the above-mentioned objectives, features, and advantages of the present invention more apparent and understandable, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] A simulation test device for glacial till seepage and particle migration under rainfall conditions, such as... Figure 1As shown, the system includes a rainfall simulation mechanism 1, a glacial moraine seepage simulation mechanism 2, a seepage monitoring system 3, and a migration and seepage monitoring system 4. The rainfall simulation mechanism 1 is used to simulate artificial rainfall, and the rainfall amount of the rainfall simulation mechanism 1 can be adjusted by a valve. The glacial moraine seepage simulation mechanism 2 includes a cylinder 201. The structure of the cylinder 201 can be cylindrical or other shapes. The cylinder 201 can be a transparent plexiglass cylinder, which is convenient for the test personnel to observe the internal seepage and fine particle migration. The inside of the cylinder 201 is provided with multiple glacial moraine filling areas. The glacial moraine filling areas of the cylinder 201 are used to fill glacial moraine samples to form a seepage medium, thereby providing a simulated test space for the seepage of glacial moraine samples under rainfall conditions. The top of the cylinder 201 has an inlet for receiving artificial rainfall, and the bottom has an outlet for discharging seepage water and migrating fine particles. The water outlet of the rainfall simulation mechanism 1 is located at the top of the inlet of the cylinder 201. The rainfall simulation mechanism 1 can be a shower or other structure. The seepage monitoring system 3 is used to monitor the seepage of glacial deposits in the cylinder 201. The seepage monitoring system 3 can be a sensor element that can monitor the amount of water in the sample. The monitoring end of the seepage monitoring system 3 is located inside the cylinder 201. The monitoring end can be set on the inner wall of the cylinder 201. The wires of the monitoring end can pass through the cylinder 201. A sealing structure needs to be set at the position where the wires pass through the cylinder 201. The seepage monitoring system 3 can have multiple monitoring ends, each located at a different depth in the cylinder 201, to monitor the seepage and moisture content changes of the glacial deposit sample at different depths. The outlet of the cylinder 201 faces the inlet of the migration and seepage monitoring system 4, which is located at the bottom of the outlet of the cylinder 201. The migration and seepage monitoring system 4 can receive fine particles migrating downward from the glacial deposit in the cylinder 201 as well as seepage water.

[0024] During the specific experimental operation, the experimenters first filled the glacial till sample into the glacial till filling area of ​​the cylinder 201, and adopted a layered filling method, that is, after each layer of sample was filled, it was lightly vibrated or compacted to ensure that the initial density of the glacial till sample was relatively uniform. After the glacial till sample was filled, the experimenters first turned on the seepage monitoring system 3 to record the initial moisture content of the glacial till sample. Then, the experimenters connected the rainfall simulation mechanism 1 to the water source, so that the rainfall simulation mechanism 1 began to simulate artificial rainfall. The simulated rainwater dripped onto the surface of the glacial till sample in the cylinder 201 and began to seep into the sample. At this time, the seepage monitoring system 3 monitored the changes in the moisture content of the sample at each depth in real time, so as to obtain the seepage rate of water at each depth and the local water stagnation. During the simulated artificial rainfall process in the rainfall simulation device 1, not only does water infiltration occur, but fine particles in the glacial till sample in cylinder 201 also migrate downwards. When water infiltrates to the bottom of cylinder 201, it detaches from cylinder 201 and falls into the migration and seepage monitoring system 4, where it is collected. Similarly, the downward-migrating fine particles can also detach from cylinder 201 and fall into the migration and seepage monitoring system 4. Researchers can determine the rainwater infiltration situation of this type of glacial till sample and the migration pattern of fine particles under infiltration conditions based on the amount of water and fine particles collected in the migration and seepage monitoring system 4.

[0025] In one embodiment, such as Figure 1 and Figure 2 As shown, the rainfall simulation mechanism 1 includes a nozzle 101 and a water supply pipe 102. The water supply pipe 102 can be a flexible or rigid pipe, which can be freely configured according to requirements. The outlet end of the water supply pipe 102 is detachably connected to the inlet end of the nozzle 101, facilitating the replacement of different water supply pipes 102 and different nozzles 101, and simplifying maintenance. The nozzle 101 is located at the top of the cylinder 201, ensuring that the water sprayed from the nozzle 101 ultimately falls into the cylinder 201. The water supply pipe 102 is connected to a water pump 103, and the inlet of the water pump 103 is connected to a water tank 104 through a pipe. The water tank 104 needs to be filled with water before the test, making it suitable for test scenarios that are far from a water source or lack an external water supply. The water pump 103 is used to pump water from the water tank 104 into the water supply pipe 102, thereby supplying water to the nozzle 101. The water supply pipe 102 is equipped with a regulating valve 105, which is used to regulate the water supply speed and water supply volume of the water supply pipe 102, thereby regulating the rainfall simulated by the nozzle 101. This facilitates the simulation of the migration of fine particles and water infiltration under different rainfall conditions, meets different test requirements, and improves applicability.

[0026] In one embodiment, such as Figure 2 and Figure 3As shown, a rainfall distribution plate 106 is installed below the nozzle 101. The rainfall distribution plate 106 has uniformly distributed micropores, with all adjacent micropores equidistant. The micropores can be created using laser drilling, and their diameter is 0.5 mm. The rainfall distribution plate 106 is made of 316L stainless steel, which has good corrosion resistance, structural rigidity, and micropore processing precision, maintaining stable aperture and uniform water distribution performance under long-term water supply and repeated testing conditions. The uniformly distributed micropores on the rainfall distribution plate 106 can evenly disperse the water sprayed from the nozzle 101, reducing the impact of localized concentrated scouring, improving the consistency of the rainfall boundary, thereby enhancing the realism of the simulated rainfall, ensuring the rigor of the experiment, and obtaining the most realistic experimental data possible.

[0027] In one embodiment, such as Figure 1 and Figure 2 As shown, an mounting plate 202 is provided above the cylinder 201. The mounting plate 202 can be installed on the base or on the outer wall of the cylinder 201 via a fixing bracket. The cylinder 201 can also be installed on the base. The nozzle 101 and the rainfall distribution plate 106 are both installed on the mounting plate 202. The mounting plate 202 provides support for the nozzle 101 and the rainfall distribution plate 106. A circular filter screen can be provided at the outlet of the cylinder 201. The diameter of the circular filter screen is equal to the inner diameter of the cylinder 201. The migration and seepage monitoring system 4 is located below the circular filter screen of the cylinder 201. The inner diameter of the inlet of the migration and seepage monitoring system 4 is smaller than the inner diameter of the cylinder 201. The axis of the inlet of the migration and seepage monitoring system 4 coincides with the axis of the cylinder 201.

[0028] During the simulation experiment, as fine particles migrate and water infiltrates, some fine particles and water can pass through the circular filter screen of the cylinder 201. However, only a portion of the fine particles and water that pass through the circular filter screen can fall into the migration and seepage monitoring system 4 and be collected. This portion of fine particles and water comes from the glacial deposit sample that is far from the edge of the cylinder 201 and close to the center. This greatly avoids the influence of the edge of the cylinder 201 on the migration of fine particles at the edge when it comes into contact with the glacial deposit sample. It also prevents the seepage water at the edge from abnormally moving and accumulating in the center, thus affecting the accuracy of the data and ensuring the authenticity and reliability of the simulation experiment data as much as possible. For fine particles and water that do not enter the migration and seepage monitoring system 4, the experimenters can also choose to collect them, for example, by laying a waterproof cloth or setting up a water basin under the device, thereby avoiding pollution of the surrounding environment.

[0029] In one embodiment, such as Figure 1 and 2As shown, a mounting plate 202 is provided above the cylinder 201. The mounting plate 202 can be installed on the base or on the outer wall of the cylinder 201 via a fixing bracket. The cylinder 201 can also be installed on the base. The nozzle 101 and the rainfall distribution plate 106 are both installed on the mounting plate 202, which supports the nozzle 101 and the rainfall distribution plate 106. An annular plate 203 is installed at the bottom of the cylinder 201. A through hole is provided in the middle of the annular plate 203. The diameter of the through hole in the annular plate 203 is smaller than the inner diameter of the cylinder 201, which is used to prevent fine particles located at the edge of the cylinder 201 from migrating downwards. The migration and seepage monitoring system 4 is located below the through hole in the annular plate 203. The through holes in the annular plate 203 allow fine particles near the center of the cylinder 201 to migrate downwards, while preventing fine particles located at the edge of the cylinder 201 from passing through the through holes. This minimizes the impact of the contact between the inner circumferential wall of the cylinder 201 and the glacial deposit sample on the migration of fine particles. The migration and seepage monitoring system collects fine particles migrating from the glacial deposit sample in the middle of the cylinder 201, thereby reducing experimental errors and improving the authenticity of the experimental data.

[0030] In one embodiment, such as Figure 1 As shown, the seepage monitoring system 3 includes a data acquisition unit 301 and moisture sensors 302. Multiple moisture sensors 302 are installed at different positions along the axial direction of the cylinder 201, and can be equidistantly distributed along a straight line to detect changes in the moisture content of the glacial till sample at different depths. A graduated scale is provided on the outer wall of the cylinder 201, which can measure the water level on the surface of the glacial till sample, allowing researchers to determine the relationship between water level, infiltration volume, and fine particle migration. At least one moisture sensor 302 is installed for each sample layer in the cylinder 201. All moisture sensors 302 are electrically connected to the data acquisition unit 301 via signal lines, enabling the data acquisition unit 301 to obtain stratified response data of the infiltration process within the glacial till sample. Moisture sensor 302 can monitor the change in moisture content of glacial till samples at different depths over time. Data acquisition instrument 301 can plot the change curves of moisture content of glacial till samples at different depths over time based on the moisture content data, and can calculate the rate of change of moisture content based on the change curves. Moreover, based on the stratified response data acquired by multiple moisture sensors 302, it can not only construct the moisture content-time response curve and moisture content-depth distribution curve inside the sample, but also obtain the dynamic evolution results of the infiltration process inside the sample through threshold identification, differential operation, interpolation fitting, and interlayer comparison, and further obtain the characteristics of seepage front advancement, local water retention, and stratified infiltration.

[0031] In one embodiment, such as Figure 1 and Figure 4As shown, the migration and seepage monitoring system 4 includes a particle collection device 401 and a seepage water collection device 402. The particle collection device 401 is used to collect fine particles migrating downwards in the cylinder 201, and the seepage water collection device 402 is used to collect water seeping from the cylinder 201. The seepage water collection device 402 is located below the outlet of the particle collection device 401 and can be a beaker or other container. The particle collection device 401 includes an upper filter screen 4011, a middle filter screen 4012, and a lower filter screen 4013, and the seepage water collection device 402 is located below the lower filter screen 4013. The upper filter screen 4011, the middle filter screen 4012, and the lower filter screen 4013 are arranged from top to bottom, with the pore size of the three screens decreasing sequentially. This allows the three filter screens to classify, intercept, and collect fine particles, enabling statistical analysis of the migration amount and particle size composition of fine particles. By weighing and sieving the particles intercepted by each screen, coupled response data between rainfall infiltration, seepage evolution, and fine particle migration can be obtained.

[0032] A simulation test method for glacial till seepage and particle migration under rainfall conditions, using the simulation test apparatus described in the above embodiment, includes the following steps: S1: The glacial deposit sample is loaded into the cylinder 201 in layers, and each layer of sample is compacted after loading. S2: Activate seepage monitoring system 3 to record the moisture content of the sample in real time; S3: Artificial rainfall is introduced into the cylinder 201 through the rainfall simulation mechanism 1; S4: Wait for fine particles and infiltration water to enter the migration and seepage monitoring system 4, shut down the rainfall simulation mechanism 1, and record the particle quantity and infiltration water quantity on the migration and seepage monitoring system 4.

[0033] In one embodiment, after the seepage monitoring system 3 is turned on, the water height on the sample surface is recorded in real time to obtain the relationship between the water height and the migration amount of fine particles and the water seepage flow rate.

[0034] In one embodiment, a glacial till sample, primarily composed of sand, silt, and fine gravel with a high fine-particle content, is filled into the cylinder 201. The sample can be filled in layers, with each layer lightly vibrated or compacted to ensure a relatively uniform initial density. During the simulation test, a set rainfall intensity is applied by adjusting the rainfall simulation mechanism 1, and the seepage monitoring system 3 monitors the gradual downward movement of the wetting front of the glacial till sample and the sequential increase in moisture content at different depths. This type of sample typically reflects the characteristics of localized waterlogging and changes in permeability with water content, making it suitable for analyzing rainfall infiltration and seepage response patterns.

[0035] In one embodiment, a glacial till sample with a wide particle size distribution, continuous particle gradation, and a combination of coarse and fine particle skeletons is filled into the cylinder 201. Different particle sizes can be pre-mixed before layered filling and leveling to form the sample. During the simulation test, the surface water height, internal wetting front advance, stratified moisture content response, and changes in permeate can be recorded simultaneously using a scale and seepage monitoring system 3. By weighing and sieving the particles trapped by different filters in the particle trapping device 401, the migration differences of different particle sizes under seepage can be analyzed. This method is suitable for characterizing the common multi-particle-size coupled seepage process in natural glacial till and reflects the correlation between rainfall infiltration and particle redistribution.

[0036] In one embodiment, when filling the cylinder 201 with a glacial till sample containing large boulders, a high proportion of coarse particles, and high overall porosity, a "coarse particle skeleton pre-arrangement + medium and fine particle filling" method can be preferentially adopted. Specifically, large-diameter boulders or gravel are first filled into the cylinder 201 in a predetermined proportion to form a skeleton, and then medium and fine particles are filled into the gaps between the coarse particles. The uniformity of filling is improved by gentle vibration. If necessary, the thickness of each filling can be appropriately reduced to avoid local structural instability caused by the coarse particles being suspended. For this type of sample, the device can still obtain the macroscopic water level changes and internal moisture content response during the infiltration process through the scale and moisture sensor 302, and obtain the infiltrate water volume and particle migration information through the infiltrate water collection device 402 and the particle trapping device 401. It is suitable for evaluating rapid infiltration, local dominant channel formation, and fine particle migration phenomena under high porosity and strong heterogeneity glacial till conditions. That is, this method is also applicable to testing glacial till samples containing large boulders.

[0037] In one embodiment, glacial deposit samples with the same gradation conditions but different initial moisture contents are filled into the cylinder 201. The initial moisture content of the samples can be controlled by pre-adding water, allowing them to settle and reach equilibrium, or allowing them to air dry naturally. Then, a comparative test is conducted using the same filling method. During the test, the moisture content change of the samples at different depths can be monitored by a moisture sensor 302. Combined with the changes in surface water height and seepage volume, the influence of the initial moisture content on the infiltration rate, the advancement of the wetting front, and the degree of fine particle migration can be analyzed. That is, this method is also applicable to seepage simulation under different moisture contents.

[0038] In one embodiment, filling the cylinder 201 with glacial till of the same gradation allows for the creation of samples with different density states by controlling the filling height, the degree of stratification and compaction, or the vibration time. During rainfall seepage tests, multi-source monitoring data can be used to compare the differences in surface water formation rate, wetting front depth, internal moisture content response, and seepage water changes under different density states. By statistically analyzing the migrating particles using the particle trapping device 401, the impact of sample density changes on the migration capacity of fine particles and the evolution of seepage channels can be further analyzed, thus demonstrating the adaptability of this device to glacial till with different structural states.

[0039] In one embodiment, the test data are calculated, assuming that the test data are arranged along the height direction of the cylinder 201. The monitoring depths corresponding to each moisture sensor 302 constitute a depth vector: The entire experimental process The time vector is composed of each sampling moment: in, Indicates the first Each monitoring depth, Indicates the first Each sampling time. The moisture sensor is at the first The volumetric water content measured at each sampling time is recorded as follows: This forms the original moisture content response matrix: To mitigate the influence of different initial moisture contents on the analytical results, the initial moisture content was used as a reference, and a moisture content increment matrix was constructed: in, In the formula, Indicates the first The monitoring depth is at the first The moisture content increment at each sampling time relative to the initial time. Based on the moisture content increment matrix. The water content-time response curves for each monitoring depth were extracted row by row: The moisture content-depth distribution curves corresponding to each sampling time were extracted by column: If necessary, interpolation fitting can be performed on data between adjacent monitoring depths to obtain a continuous water content-depth distribution profile. ; Continuous distribution profile sequence corresponding to all sampling times Used to characterize the dynamic evolution of the water content field inside a sample.

[0040] Based on the moisture content-time response curve With moisture content-depth distribution curve The dynamic evolution of infiltration within glacial till samples was analyzed. A response threshold was set. Then the first The response start time for each monitoring depth is defined as: This constitutes the response start time vector: Between adjacent sampling times The rate of change of water content at each monitoring depth is defined as: Between adjacent monitoring depths at the first The moisture content gradient at each sampling time is defined as: Based on this, the response start time, water content change rate, and water content gradient along the depth direction at each monitoring depth can be obtained.

[0041] To characterize the response sequence between different depth layers, an interlayer response hysteresis matrix is ​​constructed: in, In the formula, Indicates the first The monitoring depth is relative to the first Response lag time at each monitoring depth. Based on the response start time vector. Rate of change in moisture content and moisture content gradient It can identify the boundaries of wetted zones, transition zones, and unresponsive zones, and obtain the progression sequence, interlayer hysteresis relationship, and staged evolution characteristics of the infiltration process inside the sample in the depth direction.

[0042] Based on the dynamic evolution results, the seepage front advancement characteristics can be further obtained. A seepage front identification threshold is then set. At the sampling time The following conditions will be met. The deepest monitoring location is defined as the location of the seepage front at that moment. If the seepage front is located at an adjacent depth... and Between these, the depth of its front edge can be determined by interpolation as follows: Thus, the seepage front advancement curve is obtained: The ratio of the change in depth of the seepage front to the time interval between adjacent moments is defined as the seepage front advance rate, which is used to characterize the advance law of the wetting front over time.

[0043] Based on the dynamic evolution results, local water retention characteristics and stratified infiltration characteristics can also be obtained. A high water content threshold is set. Low rate threshold and duration threshold When the water content increment within a certain depth range is continuously higher than The rate of change in moisture content remained below And the duration is not less than At that time, it is determined that a localized stagnant zone has formed within that depth range. Furthermore, the stratification advance rate between adjacent monitoring layers is defined as: This constitutes a layered propulsion velocity vector: When the difference in advance velocity or response hysteresis between different layers exceeds a preset criterion, it is determined that there is stratified infiltration within the sample. Thus, the results of the seepage front advancement, local waterlogging distribution, and stratified infiltration characteristics of the infiltration process within the glacial till sample can be obtained.

[0044] Furthermore, at each sampling time Below, the height of the water accumulation on the sample surface is read through the height scale 7 on the outer wall of the cylinder 201 and recorded as . This forms the surface water height vector: Based on the time vector and surface water height vector Construct a surface water depth-time curve: To characterize the formation, growth, stabilization, and receding of surface water during rainfall.

[0045] Furthermore, at each sampling time Next, the cumulative volume of seepage water in the seepage water collection device 13 is read and recorded as follows. This constitutes the cumulative seepage volume vector: Based on the time vector Vector of cumulative seepage water volume Construct a cumulative seepage volume-time curve: Used to characterize the generation, accumulation, and changes of permeate during the test process.

[0046] Furthermore, after the experiment, the particles trapped by each filter layer in the particle collection device 12 were sequentially removed and dried, weighed, and sieved to obtain fine particle migration response data. The particle collection device 12 includes... Layered filter screen, for trapping particles according to If the particle size range is sieved, then the 1st particle size range will be sieved. Layered filter screen in the first The mass of particles retained within each particle size range is denoted as . This constitutes the particle migration mass matrix: in, .

[0047] In the particle migration mass matrix Further calculations can be performed on the 1st... Total mass of particles trapped by the filter screen: The total mass of migrating particles throughout the entire experiment is: This allows us to construct a particle deposition distribution sequence along the filter layer direction: And the particle migration distribution sequence along the particle size range: Furthermore, to characterize the contribution of different filter layers and different particle size ranges to particle migration, the layer mass percentage can be defined: and particle size mass ratio This allows for the acquisition of fine particle migration response data, which includes at least the total mass of migrated particles, the mass distribution of particles retained at each filter layer, the mass distribution of migrated particles in each particle size range, and their proportion characteristics. When a certain filter layer... or A significant increase indicates that obvious particle deposition has occurred at that layer; when the particle size range is significantly increased... or A significant increase indicates that the migration of fine particles within the corresponding particle size range is more pronounced.

[0048] The above-described embodiments are merely preferred embodiments of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications, improvements, and substitutions without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A simulation testing device for glacial till seepage and particle migration under rainfall conditions, characterized in that, The system includes a rainfall simulation mechanism (1) for simulating artificial rainfall, a glacial till seepage simulation mechanism (2) for filling soil samples, a seepage monitoring system (3) for monitoring glacial till seepage, and a migration and seepage monitoring system (4) for monitoring fine particle migration and water seepage. The glacial till seepage simulation mechanism (2) includes a cylinder (201) with a glacial till filling area inside. The top of the cylinder (201) has an inlet for receiving rainfall, and the bottom of the cylinder (201) has an outlet. The monitoring end of the seepage monitoring system (3) is located inside the cylinder (201), and the migration and seepage monitoring system (4) is located below the outlet of the cylinder (201).

2. The simulation test device for glacial till seepage and particle migration under rainfall conditions according to claim 1, characterized in that, The rainfall simulation mechanism (1) includes a nozzle (101) and a water supply pipe (102) connected to the nozzle (101). The nozzle (101) is located above the inlet of the cylinder (201). The water supply pipe (102) is connected to a water pump (103). The inlet of the water pump (103) is connected to a water tank (104) through a pipe. The water supply pipe (102) is equipped with a regulating valve (105) for adjusting the water volume.

3. The simulation test device for glacial till seepage and particle migration under rainfall conditions according to claim 2, characterized in that, Below the nozzle (101) is a rainfall distribution plate (106) for uniformly dispersing the water sprayed from the nozzle (101), and the rainfall distribution plate (106) is provided with uniformly distributed micropores.

4. The simulation test device for glacial till seepage and particle migration under rainfall conditions according to claim 3, characterized in that, An mounting plate (202) is provided above the cylinder (201). The cylinder (201) is mounted on the base. The nozzle (101) and the rainfall distribution plate (106) are both mounted on the mounting plate (202). An annular plate (203) is installed at the bottom of the cylinder (201). A through hole is provided in the middle of the annular plate (203). The diameter of the through hole of the annular plate (203) is smaller than the inner diameter of the cylinder (201). A migration and seepage monitoring system (4) is provided below the through hole of the annular plate (203).

5. The simulation test device for glacial till seepage and particle migration under rainfall conditions according to claim 3, characterized in that, An mounting plate (202) is provided above the cylinder (201). The cylinder (201) is mounted on the base. The nozzle (101) and the rainfall distribution plate (106) are both mounted on the mounting plate (202). A filter screen is provided at the bottom outlet of the cylinder (201). The migration and seepage monitoring system (4) is located below the filter screen. The diameter of the filter screen is equal to the inner diameter of the cylinder (201). The inner diameter of the inlet of the migration and seepage monitoring system (4) is smaller than the inner diameter of the cylinder (201). The axis of the inlet of the migration and seepage monitoring system (4) coincides with the axis of the cylinder (201).

6. The simulation test device for glacial till seepage and particle migration under rainfall conditions according to claim 1, characterized in that, The seepage monitoring system (3) includes a data acquisition instrument (301) and a moisture sensor (302). Multiple moisture sensors (302) are provided and installed at different positions along the axial direction of the cylinder (201). At least one moisture sensor (302) is provided for each sample layer in the cylinder (201). All moisture sensors (302) are electrically connected to the data acquisition instrument (301). The outer wall of the cylinder (201) is provided with a scale for measuring the water accumulation height.

7. The simulation test device for glacial till seepage and particle migration under rainfall conditions according to claim 4, characterized in that, The migration and seepage monitoring system (4) includes a particle trapping device (401) for collecting particles and an effluent collection device (402) for collecting seepage water, the effluent collection device (402) being located below the particle trapping device (401).

8. The simulation test device for glacial till seepage and particle migration under rainfall conditions according to claim 7, characterized in that, The particle collection device (401) includes an upper filter screen (4011), a middle filter screen (4012), and a lower filter screen (4013) for graded collection of fine particles. The seepage water collection device (402) is located below the lower filter screen (4013). The upper filter screen (4011), the middle filter screen (4012), and the lower filter screen (4013) are arranged in a top-to-bottom order, with the pore size of the three screens decreasing sequentially.

9. A method for simulating the seepage and particle migration of glacial deposits under rainfall conditions, using the simulation testing apparatus described in any one of claims 1-8, characterized in that, Includes the following steps: S1: The glacial deposit sample is loaded into the cylinder (201) in layers, and each layer of sample is compacted after loading. S2: Turn on the seepage monitoring system (3) and record the water content of the sample in real time; S3: Artificial rainfall is carried out inside the glacial till seepage simulation mechanism (2) through the rainfall simulation mechanism (1); S4: Wait for fine particles and infiltration water to enter the migration and seepage monitoring system (4), shut down the rainfall simulation mechanism (1), and record the amount of particles and infiltration water on the migration and seepage monitoring system (4).

10. The method for simulating and testing glacial till seepage and particle migration under rainfall conditions according to claim 9, characterized in that, After the seepage monitoring system (3) is turned on, the water height on the sample surface is recorded in real time to obtain the relationship between the water height and the migration amount of fine particles and the water seepage flow.

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