Device and method for observing the terminal channel of constant-head preferential seepage in large pores of loess

Abstract

The present invention belongs to the field of geological monitoring and discloses a device and method for observing the terminal channel of preferential seepage in large pores and constant water head in loess. The device comprises a camera, a funnel, foam glue, a first burette, a second burette, a three-way pipe for constant water head, a water bottle, a first iron stand, and a second iron stand. One end of the camera is fixed to the first iron stand. A permeable stone is set in the middle of the large opening of the funnel. The surface of the permeable stone is used to fix the original loess sample and the support tube. The space between the support tube and the loess sample is filled with foam glue. The first and third ends of the three-way pipe for constant water head are respectively connected to the water bottle and the first burette. The first burette and the second burette are connected by the second and third three-way pipes. Without disturbing the soil sample and with a fixed water head height, the terminal channel of preferential seepage in large pores and the water supply degree can be quickly observed. The work efficiency is high and the device is flexible and detachable. The device effectively solves the current problems of difficulty in capturing the preferential seepage large pore channels in loess and difficulty in measuring the water supply degree of original loess.

Description

Technical Field

[0001] The invention belongs to the field of geological monitoring and relates to a device and method for observing a loess macropore constant water head preferential seepage terminal channel. Background Art

[0002] Loess is a typical porous medium in nature, and seepage in loess has always been a key issue in loess research. While macroscopic analysis of loess seepage can generalize loess to a homogeneous, isotropic medium, at the microscale, loess seepage is heterogeneous and anisotropic. Observing seepage in loess, particularly capturing the preferential flow of water through macropores, remains a pressing challenge in the field. While computed tomography (CT) technology can now detect the pore structure of loess, scanning a single sample requires significant time, and water seepage through loess specimens is extremely rapid, making it difficult to capture this dynamic process using CT. Macropore channels reconstructed using CT scans require threshold segmentation. To identify macropores through which water can freely flow, the water content of the undisturbed loess soil must be measured. This water content can be used as the porosity of the macropores in the original loess specimen to calibrate the macropore threshold segmentation.

[0003] Currently, the capture of microscopic preferential seepage in loess macropores is achieved by intermittently adding tracer liquids and then excavating a cross-section to observe this phenomenon from the side. This method can only observe the seepage state in the soil at a specific moment, not the entire continuous seepage process. Furthermore, liquid diffusion occurs during the excavation process, making this observation method very inaccurate. Therefore, it is critical to control the water head and observe the terminal channels of preferential seepage in the macropores of undisturbed loess without damaging the loess skeleton structure, as well as to determine the water supply degree of the undisturbed loess. Summary of the Invention

[0004] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a device and method for observing the terminal channel of loess macropore constant water head preferential seepage.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] The first aspect of the present invention provides a loess macropore constant water head preferential seepage terminal channel observation device, comprising a first iron frame, a second iron frame, a first tee, a second tee, a third tee and a constant water head tee; a funnel bracket and a camera bracket are arranged from bottom to top on the first iron frame; a funnel is arranged on the funnel bracket, a permeable stone is arranged inside the funnel, a support tube is arranged on the upper edge of the permeable stone, the upper surface of the permeable stone and the inside of the support tube are used to fix the loess sample, and foam glue is filled between the loess sample and the inner wall of the support tube; a camera is arranged on the camera bracket, and the camera is located above the support tube; a burette bracket, a first bracket platform and a second bracket platform are arranged from bottom to top on the second iron frame; a first burette and a second burette are respectively arranged on both sides of the burette bracket A burette; a measuring cylinder is provided on the first support platform; a water bottle is provided on the second support platform; a first end of the first tee is connected to the funnel, and a second beaker is provided below the second end; a first end of the second tee is connected to the second burette, and a second end is connected to the third end of the first tee; a first end of the third tee is connected to the first burette, and a second end is connected to the third end of the second tee, and a first beaker is provided below the third end; a first switch is provided at the second end of the first tee, and a second switch is provided at the third end; a third switch is provided at the first end of the second tee; a fourth switch is provided at the third end of the third tee, and a fifth switch is provided at the first end; a first end of the water head tee is connected to the water bottle, a second end is located above the measuring cylinder, and a third end is connected to the first burette.

[0007] Optionally, a computer and a data cable are also included; the computer is connected to the camera via the data cable to control the camera's photo-taking process and analyze the images captured by the camera; the camera can take a photo at least once per second.

[0008] Optionally, a first height regulating valve is provided on the second support platform, and is connected to the second iron support platform through the first height regulating valve; a second height regulating valve is provided on the first support platform, and is connected to the second iron support platform through the second height regulating valve; a third height regulating valve is provided on the burette support, and is connected to the second iron support platform through the third height regulating valve.

[0009] Optionally, the vertical rod length of the first iron frame and the second iron frame is 100 cm; the funnel is a large-mouth plastic funnel with a large-mouth diameter of 30 cm and a small-mouth diameter of 0.8 cm; the support tube is a transparent plastic tube with an inner diameter of 14.5 cm, an outer diameter of 15 cm, and a height of 12 cm; the infiltration stone is a cylindrical infiltration stone with a diameter of 15 cm and a thickness of 1 cm; the second burette has a range of 100 ml and an accuracy of 0.2 ml.

[0010] Optionally, the foaming glue is a liquid mixed foaming glue.

[0011] Optionally, the camera, loess sample, permeable stone, support tube, foam glue and funnel are kept centrally aligned in the vertical direction.

[0012] Optionally, the top of the first burette is connected to the third end of the water head tee at a right angle, the first burette remains vertical, and the tube perpendicular to the third end of the water head tee remains horizontal.

[0013] Optionally, the upper position of the first burette is 10 cm lower than the upper position of the second burette.

[0014] According to a second aspect of the present invention, a method for observing the loess macropore constant water head preferential seepage terminal channel based on the above-mentioned loess macropore constant water head preferential seepage terminal channel observation device is provided, comprising: turning on the second switch, the third switch and the fifth switch, turning off the first switch and the fourth switch, starting to inject water from a water bottle until the permeable stone is completely saturated with water and the water columns in the first burette and the second burette are level, recording the scale H1 of the second burette, and turning on the first switch; obtaining an undisturbed loess sample and placing it on the surface of the permeable stone after drying, pouring foam glue between the loess sample and the inner wall of the support tube, turning off the first switch, the second switch and the fourth switch, turning on the third switch and the fifth switch, injecting water into the water bottle, adjusting the water head height in the second burette to the water head height required for the experiment; turning on the second switch until the water level scale of the second burette reaches H1; continuously injecting water, and starting to take pictures through a camera when a seepage point appears on the surface of the loess sample, and the camera takes pictures once every first preset time until the loess sample is completely saturated with water.

[0015] Optionally, the method further includes: after turning on the first switch, measuring the volume of water in the second beaker V 1. After the loess sample is completely saturated with water, turn on the fourth switch, control the water level in the second burette to be consistent with the top surface height of the loess sample, the height is H1 + preset height, and turn off the fourth switch; turn on the first switch and wait for the second preset time to measure the volume of water in the second beaker V 2; and the water content of the loess sample is obtained by the following formula: : ;in, is the volume of the loess sample, The volume of water displaced by the second burette and the first burette when the head drops by a preset height.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The present invention provides a device for observing the terminal channel of preferential seepage through large pores of loess soil using a combination of a camera, a permeable stone, a funnel, a burette, a constant head tee, and foam glue. This device provides a method for monitoring the seepage process of undisturbed loess samples with controllable head height changes. This allows the sample to maintain its original skeleton structure after water flows through its internal pores, providing lateral and bottom support. The foam glue is used to automatically fill the gap between the loess sample and the support tube, thus more conveniently providing a lateral support and water-proof boundary for the loess sample. The funnel and permeable stone combination provides a smooth and uniform flow of water into the bottom of the loess sample. Water enters from the bottom of the loess sample and exhausts upward. The water seeps through the loess sample. Due to a certain pressure head, the water preferentially seeps along the large pores, resulting in a series of preferential seepage points on the loess sample surface. This process can be recorded by continuously photographing the camera. The camera can also be used to monitor the loess surface in real time, effectively observing the terminal channel of preferential seepage through large pores in the loess sample. The space between the loess sample, support tube, and permeable stone is filled with foam. This filling method evenly fills the gaps and provides lateral support. It has good airtightness, is simple to operate, and reduces errors. This device not only observes the terminal channel of the macropore constant head preferential seepage, but also simultaneously measures the water supply degree of the loess sample. Furthermore, it has a reasonable structure, is easy to manufacture, and is flexible and disassembled for easy operation and implementation. It provides experimental verification of the preferential seepage macropores obtained through CT scanning of undisturbed loess.

[0018] Furthermore, the second support platform is connected to the second iron frame platform through a first height regulating valve, the first support platform is connected to the second iron frame platform through a second height regulating valve, and the burette support is connected to the second iron frame platform through a third height regulating valve. The combination of the height regulating valve and the constant water head tee can control the water head height and improve the accuracy of the experiment.

[0019] Furthermore, the transverse tube connecting the constant water head burette and the first burette is kept horizontal during testing, so that the water head during the experiment is fixed, thereby improving the accuracy of the experimental results.

[0020] Furthermore, the camera, loess sample, infiltration stone and funnel are located on the same straight line in the vertical direction, which makes the device better balanced during the experiment and is more conducive to observation.

[0021] Furthermore, the combination of camera and computer maintains imaging once every 1 second during the experiment, which can more accurately extract the seepage channels at the end of large pores and improve the accuracy of the experiment. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of the main structure of the loess large-pore constant-head preferential seepage terminal channel observation device according to an embodiment of the present invention.

[0023] Figure 2 This is a schematic diagram of the three-dimensional structure of the loess large-pore constant-head preferential seepage terminal channel observation device according to an embodiment of the present invention.

[0024] Figure 3 This is a schematic diagram of the calibration state of the loess macropore constant water head preferential seepage terminal channel observation device without adding loess samples according to an embodiment of the present invention.

[0025] Among them: 1-computer; 2-first iron stand; 3-funnel bracket; 4-data cable; 5-camera bracket; 6-camera; 7-support tube; 8-foaming glue; 9-loess sample; 10-funnel; 11-permeable stone; 12-first switch; 13-second switch; 14-third switch; 15-fourth switch; 16-fifth switch; 17-first burette; 18-burette bracket; 19-first bracket platform; 20-gradient cylinder; 21-constant water head tee; 22-second bracket platform; 23-water bottle; 24-first height adjustment valve; 25-second height adjustment valve; 26-third height adjustment valve; 27-second iron stand; 28-second burette; 29-first beaker; 30-second beaker. DETAILED DESCRIPTION

[0026] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0027] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0028] The present invention is described in further detail below with reference to the accompanying drawings:

[0029] See also Figures 1 to 3In one embodiment of the present invention, a loess large-pore constant-water-head preferential seepage terminal channel observation device is provided, which is characterized in that it includes a first iron frame 2, a second iron frame 27, a first tee, a second tee, a third tee and a constant-water-head tee 21.

[0030] A funnel bracket 3 and a camera bracket 5 are arranged on the first iron frame 2 from bottom to top; a funnel 10 is arranged on the funnel bracket 3, a permeable stone 11 is arranged inside the funnel 10, a support tube 7 is arranged on the upper edge of the permeable stone 11, the upper surface of the permeable stone 11 and the inside of the support tube 7 are used to fix the loess sample 9, and foam glue 8 is filled between the loess sample 9 and the inner wall of the support tube 7; a camera 6 is arranged on the camera bracket 5, and the camera 6 is located above the support tube 7; a burette bracket 18, a first bracket platform 19 and a second bracket platform 22 are arranged on the second iron frame 27 from bottom to top; a first burette 17 and a second burette 28 are respectively arranged on both sides of the burette bracket 18; a measuring cylinder 20 is arranged on the first bracket platform 19; and a water bottle 23 is arranged on the second bracket platform 22.

[0031] The first end of the first tee is connected to the funnel 10, and a second beaker 30 is set below the second end; the first end of the second tee is connected to the second burette 28, and the second end is connected to the third end of the first tee; the first end of the third tee is connected to the first burette 17, and the second end is connected to the third end of the second tee, and a first beaker 29 is set below the third end; the second end of the first tee is provided with a first switch 12, and the third end is provided with a second switch 13; the first end of the second tee is provided with a third switch 14; the third end of the third tee is provided with a fourth switch 15, and the first end is provided with a fifth switch 16; the first end of the water head tee 21 is connected to the water bottle 23, the second end is located above the measuring cylinder 20, and the third end is connected to the first burette 17.

[0032] The loess macropore constant-water-head preferential seepage terminal channel observation device 1 of the present invention utilizes a camera 6, a permeable stone 11, a funnel 10, a burette, a constant-water-head tee 21, and a foam glue 8 to provide a seepage process monitoring system capable of controlling changes in water head height for an undisturbed loess sample 9. This provides lateral and bottom support for the undisturbed loess sample 9 after water flows through the internal pores, maintaining its original skeletal structure. The foam glue 8 automatically fills the gap between the loess sample 9 and the support tube 7, thereby more conveniently providing lateral support and a water-isolating boundary for the loess sample 9. A funnel 10 and a permeable stone 11 are combined to provide a gentle and uniform infiltration of water into the bottom of the loess sample 9. Water enters the bottom of the loess sample 9, vents upward, and then seeps through the loess sample 9. Due to a certain pressure head, the water preferentially seeps along the macropores, resulting in a series of preferential seepage points on the surface of the loess sample 9. This process can be recorded by continuous camera 6 photography. This allows for real-time monitoring of the loess surface, effectively observing the terminal channels of the preferential macropores in the loess sample 9. The space between the loess sample 9, support tube 7, and permeable stone 11 is filled with foamed plastic 8. This filling method uniformly fills the gaps and provides lateral support, ensuring good airtightness, simple operation, and minimizing errors. This device not only allows observation of the terminal channels of preferential seepage at a constant water head in the macropores, but also simultaneously measures the water content of the loess sample 9. Furthermore, the device is structurally sound, easy to manufacture, and flexible, detachable, and easy to operate, providing experimental validation of the preferential macropores detected through CT scanning of untouched loess.

[0033] In a possible embodiment, the loess large pore constant head preferential seepage terminal channel observation device also includes a computer 1 and a data cable 4; the computer 1 is connected to the camera 6 via the data cable 4, and is used to control the photo-taking process of the camera 6 and analyze the captured images obtained by the camera 6; the camera 6 can take a photo at least once per second.

[0034] Specifically, the combination of the camera 6 and the computer 1 maintains imaging once per second during the experiment, which can more accurately extract the seepage channels at the end of the large pores and improve the accuracy of the experiment.

[0035] In one possible embodiment, a first height regulating valve 24 is provided on the second support platform 22, and is connected to the second iron frame 27 through the first height regulating valve 24; a second height regulating valve 25 is provided on the first support platform 19, and is connected to the second iron frame 27 through the second height regulating valve 25; a third height regulating valve 26 is provided on the burette support 18, and is connected to the second iron frame 27 through the third height regulating valve 26.

[0036] Specifically, the second support platform 22 is connected to the second iron frame 22 through the first height regulating valve 24, the first support platform 19 is connected to the second iron frame 27 through the second height regulating valve 25, and the burette support 18 is connected to the second iron frame 27 through the third height regulating valve 26. The combination of the height regulating valve and the constant water head tee 21 can control the water head height and improve the accuracy of the experiment.

[0037] In one possible embodiment, the vertical rod length of the first iron frame 2 and the second iron frame 27 is 100 cm; the funnel 10 is a large-mouth plastic funnel with a large mouth diameter of 30 cm and a small mouth diameter of 0.8 cm; the support tube 7 is a transparent plastic tube with an inner diameter of 14.5 cm, an outer diameter of 15 cm, and a height of 12 cm; the permeable stone 11 is a cylindrical permeable stone with a diameter of 15 cm and a thickness of 1 cm; the second burette 28 has a range of 100 ml and an accuracy of 0.2 ml.

[0038] Specifically, the loess sample 9 can be a cylinder with a diameter of 10 cm and a height of 10 cm. A cylindrical sample is directly carved out in the field to ensure the integrity of the original loess structure, without destroying the skeleton structure of the sample, and to ensure that the orientation of the loess sample 9 during the test is consistent with the natural sedimentation state.

[0039] Optionally, the permeable stone 11 is bonded to the bottom of the support tube 7 with waterproof glue, the side of the permeable stone 11 is bonded to the funnel 10 with waterproof glue, and the bottom of the support tube 7 is bonded to the funnel 10 with waterproof glue, which will increase the airtightness of the entire device; the loess sample 9 and the inner wall of the support tube 7 are filled and bonded with foam glue 8, which provides a lateral water-proof support boundary for the loess sample 9.

[0040] In a possible embodiment, the foam glue 8 is a liquid mixed foam glue. Specifically, the foam glue 8 is a liquid mixed foam glue with a high foaming coefficient, which can grow automatically, fill gaps and is waterproof.

[0041] In a possible embodiment, the camera 6 , loess sample 9 , permeable stone 11 , support tube 7 , foam glue 8 and funnel 10 are kept vertically aligned.

[0042] In a possible embodiment, the top of the first burette 17 is connected to the third end of the water head tee 21 at a right angle, the first burette 17 remains vertical, and the tube perpendicular to the third end of the water head tee 21 remains horizontal.

[0043] Specifically, based on the above design, it can ensure that the balance of the entire device is better during the experiment, the water flow connectivity is stronger, and it is more conducive to real-time photography and imaging of the seepage process.

[0044] In a possible embodiment, the upper position of the first burette 17 is 10 cm lower than the upper position of the second burette 28 .

[0045] Optionally, the connecting funnel 10, the second burette 28, the first burette 17, the water bottle 23, the first tee, the second tee, the third tee, and the water head tee 21 should be airtight and leak-proof. The first switch 12, the second switch 13, the third switch 14, the fourth switch 15, and the fifth switch 16 should be watertight and have a fast-response switch mechanism to ensure the accuracy of the experiment.

[0046] After the device is installed, the height of the tee pipe 21 can be adjusted to maintain a constant water head. Water flows from bottom to top through the loess sample 9, providing a seepage space for the loess sample 9. The lower part of this space is permeable and provides support, and the lateral water barriers also provide support. During the seepage process of the loess sample 9, its original pore structure remains unchanged. The surface of the loess sample 9 is an open boundary, and the camera 6 is used to continuously monitor the dynamic process of seepage at the end of the loess macropores. At the same time, the device is suitable for various soils that can produce standard samples of macropores with a constant water head, and for observing the preferential seepage end channel and measuring the water supply degree.

[0047] In another embodiment of the present invention, a method for observing the terminal channel of the large-pore constant-water-head preferential seepage in loess is provided, which can be implemented based on the above-mentioned device for observing the terminal channel of the large-pore constant-water-head preferential seepage in loess, and specifically includes the following steps:

[0048] Turn on the second switch 13, the third switch 14 and the fifth switch 16, turn off the first switch 12 and the fourth switch 15, start injecting water from the water bottle 23 until the permeable stone 11 is completely saturated with water and the water columns in the first burette 17 and the second burette 28 are level, record the scale H1 of the second burette 28, and turn on the first switch 12; obtain the undisturbed loess sample 9, dry it, and place it on the surface of the permeable stone 11, pour the foam glue 8 between the loess sample 9 and the inner wall of the support tube 7, turn off the first switch 12, the second switch 13 and the fourth switch 15, turn on the third switch 14 and the fifth switch 16, inject water into the water bottle 23, and adjust the water head height in the second burette 28 to the water head height required for the experiment; turn on the second switch 13 until the water level scale of the second burette 28 reaches H1; continue injecting water, and start taking pictures through the camera 6 when a seepage point appears on the surface of the loess sample 9, and the camera 6 takes pictures once every first preset time until the loess sample 9 is completely saturated with water.

[0049] By analyzing all the images captured by the camera, the terminal channels of the preferential seepage macropores are found and matched one-to-one with the macropores obtained by CT scanning of the loess sample 9, and the preferential seepage channels of the macropores can be analyzed.

[0050] Optionally, the loess macropore constant water head preferential seepage terminal channel observation method further includes:

[0051] After turning on the first switch 12, measure the volume of water in the second beaker 30 V 1. After the loess sample 9 is completely saturated with water, the fourth switch 15 is turned on to control the water level in the second burette 28 to be consistent with the top surface height of the loess sample 9, which is H1 + the preset height. The fourth switch 15 is turned off; the first switch 12 is turned on to remain still for the second preset time and measure the volume of water in the second beaker 30. V 2; The water content of loess sample 9 is obtained by the following formula: :

[0052]

[0053] in, is the volume of loess sample 9, The volume of water discharged when the water head of the second burette 28 and the first burette 17 drops by a preset height.

[0054] In one possible implementation, the method for observing the terminal channel of loess macropore constant water head preferential seepage specifically includes the following detailed steps:

[0055] Step 1: Dry the loess sample 9 in an oven at 105°C for 12 hours, perform a CT scan experiment, and calculate the volume of the loess sample 9 as .

[0056] Step 2: Glue the infiltration stone 11 to the middle of the funnel 10, glue the bottom surface of the support tube 7 and the surface of the infiltration stone with waterproof glue, and connect all the experimental devices such as Figure 3 As shown. Open the second switch 13, the third switch 14, and the fifth switch 16, and close the first switch 12 and the fourth switch 15. Start pouring water from the water bottle 23 until the permeable stone 11 is completely saturated with water, a water film forms on the surface of the permeable stone 11, and the water columns in the first burette 17 and the second burette 28 are level. Record the scale of the second burette 28 as H1. Open the first switch 12 and measure the volume of water in the second beaker 30. .

[0057] Step 3: Place the loess sample 9 in the middle of the surface of the permeable stone 11, pour the foam glue 8 between the loess sample 9 and the support tube 7, and the foam glue will automatically grow to the height of the loess sample 9 surface and evenly fill the gap between the loess sample 9 and the support tube 7. Connect all the experimental devices as follows Figure 1As shown, close the first switch 12, the second switch 13, and the fourth switch 15, and open the third switch 14 and the fifth switch 16. Pour water into the water bottle 23, and use the first height regulating valve 24, the second height regulating valve 25, and the third height regulating valve 26 to adjust the heights of the second support platform 22, the first support platform 19, and the first burette 17 until the water head in the second burette 28 reaches the required experimental head height. Record the scale on the first and second burettes as H2. Secure the first, second, and third height regulating valves 24, 25, and 26.

[0058] Step 4: Turn on the second switch 13 and continue to add water until the water level on the second burette 28 reaches H1. Turn on the computer 1 and the camera 6. The time at this point is recorded as T1. Continue to add water, keeping the first burette 17 overflowing. Use the graduated cylinder 20 to collect the overflowing water. Continue until the first small seepage point appears on the surface of the loess sample and start taking pictures. The time at this point is recorded as T2. Then, the camera 6 takes pictures once per second and records them on the computer 1. Each time a new seepage point appears, it is recorded as T3...T n , until the loess sample 9 is completely saturated with water, stop taking pictures and record the time T end .

[0059] Step 5: Slowly open the fourth switch 15, control the water level in the second burette 28 to be consistent with the top surface height of the loess sample 9, which is H1+10 cm, and close the fourth switch 15.

[0060] Step 6: Open the first switch 12, let it sit for 8 hours, and measure the volume of water in the second beaker. The second burette 28 and the first burette 17, the head drops 10cm, and the volume of water discharged is , the water content of loess sample 9 is recorded as , the calculation formula is: .

[0061] Step 7: Analyze all the images taken to find the end channels of the preferential seepage macropores, and make a one-to-one correspondence with the macropores obtained by CT scanning of loess sample 9 to analyze the preferential seepage channels of the macropores.

[0062] The device and method for observing the terminal channel of large-pore constant-water-head preferential seepage in loess of the present invention have a simple structure, convenient sample preparation, low cost, can control the water head height, do not disturb the soil sample, can quickly observe the terminal channel of large-pore constant-water-head preferential seepage in regular soil samples and the water supply degree of regular soil samples, have high working efficiency, and are flexible and detachable.

[0063] The above content is only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A loess macropore constant water head preferential seepage terminal channel observation device, characterized in that: It comprises a first iron frame platform (2), a second iron frame platform (27), a first tee pipe, a second tee pipe, a third tee pipe and a fixed water head tee pipe (21); A funnel support (3) and a camera support (5) are provided on the first iron frame (2) from bottom to top; a funnel (10) is provided on the funnel support (3), a permeable stone (11) is provided inside the funnel (10), a support tube (7) is provided on the upper edge of the permeable stone (11), the upper surface of the permeable stone (11) and the inside of the support tube (7) are used to fix the loess sample (9), and a foam glue (8) is filled between the loess sample (9) and the inner wall of the support tube (7); a camera (6) is provided on the camera support (5), and the camera (6) is located above the support tube (7); a burette support (18), a first support platform (19) and a second support platform (22) are provided on the second iron frame (27) from bottom to top; a first burette (17) and a second burette (28) are provided on both sides of the burette support (18); a measuring cylinder (20) is provided on the first support platform (19); and a water bottle (23) is provided on the second support platform (22); The first end of the first tee is connected to the funnel (10), and a second beaker (30) is provided below the second end; the first end of the second tee is connected to the second burette (28), and the second end is connected to the third end of the first tee; the first end of the third tee is connected to the first burette (17), and the second end is connected to the third end of the second tee, and a first beaker (29) is provided below the third end; the second end of the first tee is provided with a first switch (12), and the third end is provided with a second switch (13); the first end of the second tee is provided with a third switch (14); the third end of the third tee is provided with a fourth switch (15), and the first end is provided with a fifth switch (16); the first end of the fixed water head tee (21) is connected to the water bottle (23), the second end is located above the measuring cylinder (20), and the third end is connected to the first burette (17).

2. The loess macropore constant water head preferential seepage terminal channel observation device according to claim 1 is characterized in that: Also includes a computer (1) and a data cable (4); The computer (1) is connected to the camera (6) via a data line (4) and is used to control the photographing process of the camera (6) and analyze the photographed images obtained by the camera (6); the camera (6) is capable of taking a photograph at least once per second.

3. The loess macropore constant water head preferential seepage terminal channel observation device according to claim 1, characterized in that: A first height regulating valve (24) is provided on the second support platform (22), and the second support platform (22) is connected to the second iron frame platform (27) via the first height regulating valve (24); A second height regulating valve (25) is provided on the first support platform (19), and is connected to the second iron frame platform (27) via the second height regulating valve (25); The burette support (18) is provided with a third height regulating valve (26) and is connected to the second iron frame (27) via the third height regulating valve (26).

4. The loess macropore constant water head preferential seepage terminal channel observation device according to claim 1, characterized in that: The vertical rod lengths of the first iron frame (2) and the second iron frame (27) are 100 cm; the funnel (10) is a large-mouth plastic funnel with a large-mouth diameter of 30 cm and a small-mouth diameter of 0.8 cm; The support tube (7) is a transparent plastic tube with an inner diameter of 14.5 cm, an outer diameter of 15 cm, and a height of 12 cm. The permeable stone (11) is a cylindrical permeable stone with a diameter of 15 cm and a thickness of 1 cm. The second burette (28) has a range of 100 ml and an accuracy of 0.2 ml.

5. The loess macropore constant water head preferential seepage terminal channel observation device according to claim 1, characterized in that: The foaming glue (8) is a liquid mixed foaming glue.

6. The loess macropore constant water head preferential seepage terminal channel observation device according to claim 1, characterized in that: The camera (6), loess sample (9), permeable stone (11), support tube (7), foam glue (8) and funnel (10) are kept centrally aligned in the vertical direction.

7. The loess macropore constant water head preferential seepage terminal channel observation device according to claim 1, characterized in that: The top of the first burette (17) is connected to the third end of the water head tee (21) at a right angle, the first burette (17) remains vertical, and the tube perpendicular to the third end of the water head tee (21) remains horizontal.

8. The loess macropore constant water head preferential seepage terminal channel observation device according to claim 1, characterized in that: The upper position of the first burette (17) is 10 cm lower than the upper position of the second burette (28).

9. A method for observing the terminal channel of loess macropore constant water head preferential seepage based on the loess macropore constant water head preferential seepage terminal channel observation device according to any one of claims 1 to 8, characterized in that: include: Open the second switch (13), the third switch (14) and the fifth switch (16), close the first switch (12) and the fourth switch (15), start filling water from the water bottle (23), until the permeation stone (11) is completely saturated with water and the water columns in the first burette (17) and the second burette (28) are level, record the scale H1 of the second burette (28), and open the first switch (12); Obtain an undisturbed loess sample (9), dry it, and place it on the surface of the permeable stone (11). Pour foam glue (8) between the loess sample (9) and the inner wall of the support tube (7). Close the first switch (12), the second switch (13), and the fourth switch (15). Open the third switch (14) and the fifth switch (16). Fill the water bottle (23) with water and adjust the water head height in the second burette (28) to the water head height required for the experiment. The second switch (13) is turned on until the water level scale of the second burette (28) reaches H1; water is continuously injected, and when a seepage point appears on the surface of the loess sample (9), the camera (6) starts taking pictures, and the camera (6) takes pictures once every first preset time until the loess sample (9) is completely saturated with water.

10. The method for observing the terminal channel of the loess macropore constant water head preferential seepage according to claim 9, characterized in that: Also includes: After turning on the first switch (12), measure the volume of water in the second beaker (30) V 1; After the loess sample (9) is completely saturated with water, the fourth switch (15) is turned on, and the water level in the second burette (28) is controlled to be consistent with the top surface height of the loess sample (9), which is H1 + a preset height, and the fourth switch (15) is turned off; the first switch (12) is turned on, and the sample is left still for a second preset time and the volume of water in the second beaker (30) is measured. V 2; and the water content of loess sample (9) is obtained by the following formula: : ; in, is the volume of loess sample (9), The volume of water discharged when the water head of the second burette (28) and the first burette (17) drops by a preset height.

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