A vertical shaft frozen soil blasting model test system and use method

Abstract

The present invention provides a vertical shaft frozen soil blasting model test system and a use method. The test system includes a reaction frame, a sample preparation device, a vertical shaft, a freezing device and a monitoring device; a jack is arranged in the middle of the reaction frame; the sample preparation device includes a top cover, a barrel and a base; the inner cavity formed between the vertical shaft and the barrel is used to arrange the frozen soil sample; the freezing device is arranged on the periphery of the vertical shaft; and the monitoring device is used to monitor the vibration propagation law during the frozen soil blasting. The use method of the test system in the present invention is to prepare the frozen soil sample, arrange the detonator and explosives, simulate the excavation by blasting, and collect the blasting vibration data during the blasting process. The test system in the present invention has a simple structure and is detachable, so that rapid sample preparation can be achieved; the triaxial stress loading simulates different ground stresses, and simulation under different excavation conditions can be achieved; and the test system can be used to simulate the vibration law under different blasting schemes and the deformation law of the frozen soil sample and the vertical shaft wall during the cyclic excavation advancement process.

Description

Technical Field

[0001] The invention belongs to the technical field of frozen soil blasting, and in particular relates to a vertical shaft frozen soil blasting model test system and a use method thereof. Background Art

[0002] Frozen soil blasting is widely used in transportation engineering construction, mining and urban expansion in cold regions. When encountering a large amount of frozen soil, excavation and blasting are carried out in the frozen soil. When vertical shaft construction passes through a thick and unstable topsoil layer, the freezing method is mostly used. However, due to concerns that blasting will cause the frozen pipe to break and there is no practical experience to follow, the selection of blasting parameters in on-site vertical shaft frozen soil construction is very blind, not only the construction safety is not guaranteed, but also the construction efficiency is low; in addition, the propagation process of blasting is very complicated and is affected by many factors. When the blasting vibration reaches a certain intensity, it will cause the strength of the shaft wall to decrease or become unstable, and even lead to engineering hazards such as collapse. Therefore, in the process of building the shaft wall, it is also necessary to study the influence of blasting parameters on the vibration of the shaft wall and determine the maximum blasting vibration that the shaft wall can withstand.

[0003] In order to optimize the blasting process, it is necessary to conduct field tests to study the blasting characteristics based on the actual project conditions. In the field tests, since the depth of the shaft increases continuously with the blasting excavation, the buried depths of the blasting detonators are different, the axial and circumferential ground stresses on the shaft are different. At different shaft depths, the blasting has an impact on the shaft wall, the freezing pipe, and the propagation law of the blasting. The on-site blasting conditions are very complicated, and it is obviously unrealistic to optimize the blasting process through a large number of field tests.

[0004] Therefore, it is necessary to conduct multiple tests to simulate the on-site conditions through model tests, analyze and compare different blasting schemes, and determine the reasonable frozen soil blasting charge structure and blasting parameters, especially the charge density coefficient, through experiments to optimize the blasting process. Summary of the invention

[0005] The purpose of the present invention is to provide a vertical shaft frozen soil blasting model test system and a use method, so as to solve the problem of difficulty in studying blasting characteristics by field tests, and solve the problems of no guarantee of construction safety and low construction efficiency.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A vertical shaft frozen soil blasting model test system, the test system comprising a reaction frame, a sample preparation device, a vertical shaft, a freezing device and a monitoring device;

[0008] A jack is arranged in the middle of the reaction frame, and the jack is used to apply axial pressure to the sample preparation device;

[0009] The sample preparation device is arranged directly below the jack, and comprises a top cover, a barrel body and a base, wherein the barrel body is detachably fixedly connected to the top cover and the base;

[0010] The vertical shaft passes through the top cover and is coaxially arranged with the barrel body. The inner cavity formed between the vertical shaft and the barrel body is used to arrange frozen soil samples. A bottom gun blank area is arranged at the bottom of the vertical shaft. The bottom gun blank area is used to arrange drilling equipment. The bottom of the bottom gun blank area forms a blasting surface.

[0011] The freezing device comprises a plurality of freezing pipes, which sequentially pass through the top cover and the frozen soil sample and extend to the base, the freezing pipes are arranged parallel to the extension direction of the shaft, and the plurality of freezing pipes are arranged at the periphery of the shaft;

[0012] The monitoring device includes a plurality of vibration sensors, which are arranged radially and longitudinally along the outer side of the blasting surface, and are used to monitor the vibration propagation law during frozen soil blasting.

[0013] As described above, the vertical shaft frozen soil blasting model test system, as a preferred solution, the monitoring device further comprises a plurality of first strain gauges and a plurality of second strain gauges, the plurality of first strain gauges are arranged along the longitudinal direction of the vertical shaft wall, and the plurality of second strain gauges are arranged along the longitudinal direction of the freezing pipe;

[0014] The first strain gauge and the second strain gauge are connected to a dynamic strain gauge through a data signal line, and the dynamic strain gauge is used to perform dynamic strain test and vibration test on the shaft wall and the freezing pipe;

[0015] Preferably, the monitoring device also includes a pressure box and a displacement meter, and the pressure box and the displacement meter are respectively connected to a static monitor via data signal lines, and the static monitor is used to monitor the convergence deformation of the shaft wall and the displacement and deformation of the frozen soil sample during blasting excavation.

[0016] As a preferred solution, the vertical shaft frozen soil blasting model test system as described above further includes a data acquisition device, which is connected to the vibration sensor via a data signal line and is used to collect vibration data monitored by the vibration sensor.

[0017] As described above, the vertical shaft frozen soil blasting model test system, as a preferred solution, the freezing device also includes a refrigeration device, the refrigeration device is connected to the freezing pipe, and the refrigeration device is used to control the freezing temperature of the frozen soil sample;

[0018] Preferably, four freezing pipes are provided, and the four freezing pipes are evenly arranged along the circumference adjacent to the shaft wall.

[0019] As a preferred embodiment of the vertical shaft frozen soil blasting model test system, the barrel body comprises two half barrel bodies, and the two half barrel bodies are fastened and connected by connecting bolts;

[0020] Preferably, a plurality of bolt fixing blocks are evenly arranged on both sides of the half barrel body in the longitudinal direction, and the connecting bolts are used to fix and connect the two half barrel bodies via the bolt fixing blocks.

[0021] As a preferred embodiment of the vertical shaft frozen soil blasting model test system, the top cover and the base are both disc-shaped, and the outer diameters of the top cover and the base are both larger than the outer diameter of the barrel;

[0022] Preferably, the size of the top cover is the same as the size of the base;

[0023] More preferably, the barrel body and the top cover are fastened together by connecting bolts, and the barrel body and the base are fastened together by connecting bolts; a plurality of bolt fixing blocks are arranged on the sides of the top and bottom of the barrel body along the circumferential direction, and the connecting bolts fix the top end of the barrel body to the top cover through the bolt fixing blocks, and the connecting bolts fix the bottom end of the barrel body to the base through the bolt fixing blocks.

[0024] As a preferred embodiment of the vertical shaft frozen soil blasting model test system, a rubber sleeve is provided between the barrel and the frozen soil sample, the rubber sleeve is adhered to the inner wall of the barrel, and an oil pressure chamber is formed inside the rubber sleeve;

[0025] The rubber sleeve is connected with an oil injection device, and the oil injection device injects oil into the oil pressure cavity to apply circumferential pressure to the frozen soil sample through the oil pressure;

[0026] Preferably, the oil filling device includes an oil filling port and an oil delivery pipe, the oil filling port passes through the inner and outer walls of the barrel body and is connected to the oil pressure chamber of the rubber sleeve, one end of the oil delivery pipe is connected to the input end of the oil filling port, and the other end is connected to a throttle valve.

[0027] As the vertical shaft frozen soil blasting model test system described above, as a preferred solution, a handle is provided on the outer wall of the barrel, and the handle is used to lift the sample preparation device;

[0028] Preferably, scale lines are provided on the inner wall of the barrel, and the scale lines are used to mark the volume of the sample preparation device.

[0029] As a preferred embodiment of the vertical shaft frozen soil blasting model test system, a plurality of legs are arranged along the circumferential direction below the base, and the legs are used to support the sample preparation device;

[0030] Preferably, the number of the legs is four, and the four legs are evenly arranged along the circumferential direction of the base;

[0031] More preferably, the legs are steel pipe legs.

[0032] A method for using the vertical shaft frozen soil blasting model test system as described above, the method comprising the following steps:

[0033] Step S1, adjusting the moisture content according to the density of the pre-compacted sample, adding the sample into the inner cavity of the sample preparation device in multiple times, freezing it through a freezing tube after layered compaction, and obtaining a frozen soil sample;

[0034] Step S2, drilling holes in the frozen soil sample within the vertical shaft and arranging detonators and explosives to simulate different blasting schemes;

[0035] Step S3, applying axial pressure and circumferential pressure to the frozen soil sample to simulate the ground stress of the frozen soil sample under different excavation conditions, blasting the frozen soil in the middle shaft to simulate excavation, and monitoring and collecting blasting vibration data during the blasting process.

[0036] Compared with the closest prior art, the technical solution provided by the present invention has the following excellent effects:

[0037] The sample preparation device in the test system of the present invention has a simple structure, can be disassembled, and is easy to move. A scale is set on the inner wall of the barrel of the sample preparation device, and frozen soil samples of different densities can be prepared according to volume and mass, thereby realizing rapid sample preparation.

[0038] The vertical shaft of the test system in the present invention is set in the middle of the sample preparation device, and pressure is applied to the top cover of the sample preparation device through a jack, thereby generating axial pressure on the frozen soil sample. By injecting oil into the rubber sleeve, the oil pressure applies circumferential pressure to the frozen soil sample, realizing triaxial stress loading to simulate different ground stress conditions, and realizing simulation under different excavation conditions.

[0039] The present invention prepares frozen soil samples by layered compaction. During the compaction process, vibration sensors are respectively arranged above and below the blasting surface and in the radial direction to monitor the law of blasting vibration propagation. Strain gauges are pasted on freezing pipes to study the dynamic response of the freezing pipes. Strain gauges are pasted on the walls of vertical shafts to study the influence of different blasting parameters on the walls of vertical shafts. The test system can be used to simulate different blasting schemes, different blasting parameters, blasting charges, inter-row spacings, vibration laws under different blasting footage conditions, and deformation laws of frozen soil samples and vertical shaft walls during cyclic excavation and advancement. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. Among them:

[0041] Figure 1 It is a schematic diagram of the three-dimensional structure of a vertical shaft frozen soil blasting model test system in a specific embodiment of the present invention;

[0042] Figure 2 It is a partial cutaway stereoscopic diagram of a vertical shaft frozen soil blasting model test system in a specific embodiment of the present invention;

[0043] Figure 3 It is a schematic diagram of the internal structure of the vertical shaft frozen soil blasting model test system in a specific embodiment of the present invention;

[0044] Figure 4 It is a schematic diagram of the top view of the structure of the barrel body, the vertical shaft and the freezing pipe in a specific embodiment of the present invention.

[0045] In the figure: 1. reaction frame; 2. jack; 3. top cover; 4. barrel; 403. rubber sleeve; 4031. oil pressure chamber; 404. oil filling device; 405. handle; 5. base; 501. support leg; 6. vertical shaft; 601. bottom gun blank area; 7. bolt fixing block; 701. connecting bolt; 8. freezing pipe; 9. vibration sensor; 10. first strain gauge; 11. second strain gauge. DETAILED DESCRIPTION

[0046] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention belong to the scope of protection of the present invention.

[0047] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be noted that the embodiments and features in the embodiments of the present invention can be combined with each other without conflict.

[0048] In the test system of the present invention, the vertical shaft 6 is arranged in the middle of the sample preparation device, and pressure is applied to the top cover 3 of the sample preparation device through the jack 2, so as to generate axial pressure on the frozen soil sample, and oil is injected into the rubber sleeve 403, and the oil pressure applies circumferential pressure to the frozen soil sample, so as to realize triaxial stress loading to simulate different ground stress conditions, and the middle vertical shaft 6 is blasted to simulate excavation; the frozen soil sample is prepared by layered compaction, and in the process of compacting the soil, vibration sensors 9 are respectively arranged above and below the blasting surface and in the radial direction to monitor the law of vibration propagation, strain gauges are pasted on the freezing pipe 8 to study the dynamic response of the freezing pipe 8, and strain gauges are pasted on the wall of the vertical shaft 6 to study the influence of different blasting parameters on the wall of the vertical shaft 6.

[0049] like Figure 1 to Figure 4As shown, the present invention provides a vertical shaft frozen soil blasting model test system, the test system includes a reaction frame 1, a sample preparation device, a vertical shaft 6, a freezing device and a monitoring device.

[0050] A jack 2 is arranged in the middle of the reaction frame 1, and the jack 2 is used to apply axial pressure to the sample preparation device.

[0051] The sample preparation device is arranged directly below the jack 2. The sample preparation device includes a top cover 3, a barrel 4 and a base 5. In this specific embodiment, the outer diameters of the top cover 3 and the base 5 are both Φ700mm, the outer diameter of the barrel 4 is Φ630mm, the inner diameter of the barrel 4 is Φ600mm, and the wall thickness of the barrel 4 is 15mm; the barrel 4 is detachably fixedly connected to the top cover 3 and the base 5. In a specific embodiment of the present invention, the barrel 4 includes two half barrels, which are fastened and connected by connecting bolts 701; preferably, a plurality of bolt fixing blocks 7 are evenly arranged on both sides of the half barrel along the longitudinal direction, and the connecting bolts 701 fix the two half barrels through the bolt fixing blocks 7. Preferably, the bolt fixing blocks 7 are square nuts. Three bolt fixing blocks 7 are evenly arranged on both sides of the half barrel along the longitudinal direction, and the bolt fixing blocks 7 are welded to both sides of the half barrel. The bolt fixing blocks 7 are square blocks with a cross-sectional size of 40mm×40mm, and the model of the connecting bolts 701 is M16.

[0052] In a specific embodiment of the present invention, the top cover 3 and the base 5 are both disc-shaped, and the outer diameters of the top cover 3 and the base 5 are both larger than the outer diameter of the barrel body 4; preferably, the size of the top cover 3 is the same as that of the base 5; more preferably, the barrel body 4 and the top cover 3 are fastened and connected by connecting bolts 701, and the barrel body 4 and the base 5 are fastened and connected by connecting bolts 701; the sides of the top and bottom of the barrel body 4 are both provided with a plurality of bolt fixing blocks 7 along the circumferential direction, and the bolt fixing blocks 7 are welded to the sides of the top and bottom of the barrel body 4, and the connecting bolts 701 are used to fix the top end of the barrel body 4 with the top cover 3 through the bolt fixing blocks 7, and the connecting bolts 701 are used to fix the bottom end of the barrel body 4 with the base 5 through the bolt fixing blocks 7. Preferably, four bolt fixing blocks 7 are evenly provided on the sides of the top and bottom of the barrel body 4 along the circumferential direction.

[0053] like Figure 4 As shown, in a specific embodiment of the present invention, a rubber sleeve 403 is provided between the barrel body 4 and the frozen soil sample, the rubber sleeve 403 is adhered to the inner wall of the barrel body 4, and an oil pressure chamber 4031 is formed inside the rubber sleeve 403;

[0054] The rubber sleeve 403 is connected to an oil injection device 404, and the oil injection device 404 injects oil into the oil pressure chamber 4031, and applies circumferential pressure to the frozen soil sample through the oil pressure;

[0055] Preferably, the oil injection device 404 includes an oil injection port and an oil delivery pipe, the oil injection port penetrates the inner and outer walls of the barrel body 4 and communicates with the oil pressure chamber of the rubber sleeve 403, one end of the oil delivery pipe is communicated with the input end of the oil injection port, and the other end is connected with a throttle valve. Preferably, the rubber sleeve 403 is an annular rubber sleeve, which is adhered to the inner wall of the barrel body 4.

[0056] In a specific embodiment of the present invention, the rubber sleeve 403 is actually equivalent to an air bag, and the rubber sleeve 403 is filled with hydraulic oil to apply circumferential pressure to the frozen soil sample in the sample preparation device.

[0057] In a specific embodiment of the present invention, the rubber sleeve 403 is actually equivalent to an air bag, and the rubber sleeve 403 is filled with hydraulic oil to apply circumferential pressure to the frozen soil sample in the sample preparation device.

[0058] In a specific embodiment of the present invention, a handle 405 is provided on the outer wall of the barrel body 4, and the handle 405 is used to lift the sample preparation device; preferably, the handle 405 is a circular ring handle.

[0059] In a specific embodiment of the present invention, scale lines are provided on the inner wall of the barrel 4, and the scale lines are used to mark the volume of the sample preparation device. The frozen soil samples of different densities are prepared according to the volume and mass. When preparing frozen soil samples of the same density, the density after compaction is ensured to be consistent according to the mass of the weighed soil sample, and the soil sample is compacted according to the volume displayed by the scale lines on the sample preparation device.

[0060] In a specific embodiment of the present invention, a plurality of legs 501 are arranged along the circumferential direction below the base, and the legs 501 are used to support the sample preparation device; preferably, the number of the legs 501 is four, and the four legs 501 are evenly arranged along the circumferential direction of the base; more preferably, the legs 501 are steel pipe legs. In this specific embodiment, the length of the legs is 150 mm and the diameter is Φ32 mm. Figure 2 As shown, the vertical shaft 6 passes through the top cover 3 and is coaxially arranged with the barrel body 4. The inner cavity formed between the vertical shaft 6 and the barrel body 4 is used to arrange the frozen soil sample. The bottom of the vertical shaft 6 is provided with a bottom gun blank area 601, and the bottom gun blank area 601 is used to arrange the drilling equipment. The bottom of the bottom gun blank area forms a blasting surface. The purpose of setting the bottom gun blank area is to facilitate drilling. A template is arranged above the bottom gun blank area. In order to ensure the diameter of the excavation profile, a certain space must be provided for drilling and arranging the drilling equipment. A hole is opened in the middle position of the top cover 3, and the hole corresponds to the vertical shaft 6. The vertical shaft 6 extends through the hole into the frozen soil sample. Preferably, the inner diameter of the hole is greater than or equal to the outer diameter of the vertical shaft 6. In this specific embodiment, the inner diameter of the hole is Φ200mm, the outer diameter of the vertical shaft 6 is Φ200mm, the inner diameter of the vertical shaft 6 is Φ160mm, and the inner wall of the vertical shaft 6 is provided with a concrete template with a radius of 80mm to facilitate pouring concrete, and the depth of the vertical shaft 6 increases continuously with blasting excavation.

[0061] The freezing device includes a plurality of freezing pipes 8, which sequentially pass through the top cover 3 and the frozen soil sample and extend to the base 5. A through hole corresponding to the freezing pipe 8 is provided on the top cover 3, and the inner diameter of the through hole is greater than or equal to the outer diameter of the freezing pipe 8. The freezing pipe 8 is arranged parallel to the extension direction of the vertical shaft 6. A plurality of freezing pipes 8 are arranged at the periphery of the vertical shaft 6 and along the circumferential direction of the wall of the adjacent vertical shaft 6. There is a freezing hole corresponding to the freezing pipe 8, and the freezing hole passes through the frozen soil sample. The freezing pipe 8 extends from the top of the freezing hole along the depth direction of the freezing hole to the bottom of the freezing hole.

[0062] In a specific embodiment of the present invention, the freezing device further comprises a refrigeration device, which is connected to the freezing pipe 8 and is used to control the freezing temperature of the frozen soil sample;

[0063] Preferably, four freezing pipes 8 are provided, and the four freezing pipes 8 are evenly arranged along the circumference of the adjacent vertical shaft 6 .

[0064] like Figure 3 As shown, the monitoring device includes a plurality of vibration sensors 9, which are arranged radially and longitudinally outside the blasting surface. The vibration sensors 9 are used to monitor the vibration propagation law during frozen soil blasting. Preferably, the vibration sensors 9 are arranged at equal intervals in the radial and longitudinal directions outside the blasting surface. 3 to 5 (for example, 3, 4, 5) vibration sensors 9 are arranged at equal intervals in the frozen soil samples above and below the blasting surface, and 3 to 5 (for example, 3, 4, 5) vibration sensors 9 are arranged at equal intervals in the radial direction outside the blasting surface.

[0065] In a specific embodiment of the present invention, the monitoring device further includes a plurality of first strain gauges 10 and a plurality of second strain gauges 11. The first strain gauges 10 are arranged along the longitudinal direction of the wall of the shaft 6, and the first strain gauges 10 are arranged on the inner wall of the shaft 6; the second strain gauges 11 are arranged along the longitudinal direction of the freezing pipe 8, and the second strain gauges 11 are arranged on the outer wall of the freezing pipe; preferably, four first strain gauges 10 are arranged, and the four first strain gauges 10 are arranged linearly and equidistantly along the longitudinal direction of the wall of the shaft 6; more preferably, five second strain gauges 11 are arranged, and the five second strain gauges 11 are arranged linearly and equidistantly along the longitudinal direction of the freezing pipe 8. There are multiple freezing pipes 8, and since the freezing pipes 8 are evenly arranged along the axial direction of the adjacent shaft 6, it is sufficient to arrange the second strain gauge 11 on only one of the freezing pipes 8.

[0066] The first strain gauge 10 and the second strain gauge 11 are connected to the dynamic strain gauge through the data signal line, wherein the dynamic strain gauge is a multi-channel combination. In this specific embodiment, the dynamic strain gauge has more than sixteen channels. Preferably, the model of the dynamic strain gauge is DH5922N; multiple first strain gauges 10 and multiple second strain gauges 11 are respectively plugged into the corresponding channels on the dynamic strain gauge through the data signal line, and the dynamic strain gauge is used to perform dynamic strain test and vibration test on the wall of the vertical shaft 6 and the freezing pipe 8. The dynamic strain gauge can obtain the influence of different blasting parameters on the wall of the vertical shaft 6 through the first strain gauge 10, and the dynamic response of the freezing pipe 8 through the second strain gauge 11.

[0067] In a specific embodiment of the present invention, the monitoring device also includes a pressure box (not marked in the figure) and a displacement meter (not marked in the figure). The pressure box and the displacement meter are respectively connected to a static monitor via data signal lines. The static monitor is used to monitor the convergence deformation of the shaft wall and the displacement and deformation of the frozen soil sample during blasting excavation.

[0068] In a specific embodiment of the present invention, the test system further includes a data acquisition device, which is connected to the vibration sensor 9 via a data signal line and is used to acquire vibration data monitored by the vibration sensor 9 .

[0069] In order to better understand the vertical shaft 6 frozen soil blasting model test system of the present invention, the present invention also provides a method for using the vertical shaft 6 frozen soil blasting model test system, and the method for using includes the following steps:

[0070] Step S1, according to the density of the pre-compacted sample, adjust the moisture content, add the sample into the inner cavity of the sample preparation device for multiple times, and freeze it through the freezing tube 8 after layered compaction to obtain a frozen soil sample. The sample is added into the inner cavity for multiple times. In a specific embodiment, a certain mass of sample can be weighed according to a layer of 10 cm thickness (the stacking volume is greater than the volume of 10 cm after the sample is compacted), and then compacted to a thickness of 10 cm, and then a certain mass of sample is weighed again and added to the inner cavity for compaction; the compaction process generally uses a wooden hammer or a small compactor, lifts the small compactor to a certain height, and compacts from the periphery to the middle;

[0071] During the layered compaction process, vibration sensors 9 are arranged above, below and radially of the blasting surface to detect the vibration propagation law; four first strain gauges 10 are pasted on the wall of the vertical shaft 6 at equal intervals in the longitudinal direction, and the four first strain gauges 10 are respectively plugged into the dynamic strain gauge through data signal lines, and the influence of different blasting parameters on the wall of the vertical shaft 6 is measured by the dynamic strain gauge; five second strain gauges 11 are pasted on the freezing pipe 8 at equal intervals in the longitudinal direction, and the five second strain gauges 11 are respectively plugged into the dynamic strain gauge through data signal lines, and the dynamic response of the freezing pipe 8 is measured by the dynamic strain gauge.

[0072] Step S2, drilling holes in the frozen soil sample within the vertical shaft and arranging detonators and explosives to simulate different blasting schemes. Among them, different blasting schemes include simulating different blasting parameters, blasting charges, spacing, blasting vibration laws under different blasting footage conditions, and deformation laws of the frozen soil sample and the wall of the vertical shaft 6 during the cyclic excavation process; in addition, in order to facilitate drilling, the blasting point needs to be at a certain distance from the wall of the vertical shaft 6, generally 30 to 40 mm; when arranging detonators and explosives, holes can be drilled in circles to achieve segmented blasting excavation.

[0073] Step S3, apply axial pressure and circumferential pressure to the frozen soil sample to simulate the ground stress of the frozen soil sample under different excavation conditions, and simulate the excavation of the frozen soil blasting in the middle shaft 6, while monitoring and collecting the blasting vibration data during the blasting process. During the blasting simulation, in order to ensure that the circumferential pressure and axial pressure on the frozen soil sample can be simulated, it is not necessary to remove the sample preparation device outside the frozen soil sample; under different excavation conditions, the depth of the shaft 6 is different, and the ground stress on the frozen soil sample is not too much. According to the ground stress to be simulated, a certain axial pressure is applied to the frozen soil sample by the jack 2, and hydraulic oil is injected into the rubber sleeve 403 through the oil injection device 404. The oil pressure in the rubber sleeve 403 applies a certain circumferential pressure to the frozen soil sample; when the frozen soil blasting in the middle shaft 6 simulates the excavation, the vibration data is collected The instrument can collect data on blasting vibration, measure the dynamic response of blasting on the freezing pipe 8 and the impact on the wall of the vertical shaft 6 through the dynamic strain meter, monitor the convergence deformation of the vertical shaft wall and the displacement and deformation of the frozen soil sample during blasting excavation through the static monitoring instrument, and process these measurement data in the later stage and analyze them in combination with the destruction characteristics of the frozen soil sample after blasting. In order to realize blasting excavation of frozen soil in the vertical shaft, the parameters required for the strength support of the vertical shaft wall under different frozen soil sample parameters are analyzed and compared after multiple simulation experiments to select the optimal blasting process.

[0074] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are within the scope of protection of the pending claims of the present invention.

Claims

1. A vertical shaft frozen soil blasting model test system, characterized in that: The test system includes a reaction frame, a sample preparation device, a vertical shaft, a freezing device and a monitoring device; A jack is arranged in the middle of the reaction frame, and the jack is used to apply axial pressure to the sample preparation device; the sample preparation device is arranged directly below the jack, and the sample preparation device comprises a top cover, a barrel body and a base, and the barrel body, the top cover and the base are all detachably connected; The vertical shaft passes through the top cover and is coaxially arranged with the barrel body. The inner cavity formed between the vertical shaft and the barrel body is used to arrange frozen soil samples. A bottom gun blank area is arranged at the bottom of the vertical shaft. The bottom gun blank area is used to arrange drilling equipment. The bottom of the bottom gun blank area forms a blasting surface. The freezing device comprises a plurality of freezing pipes, which sequentially pass through the top cover and the frozen soil sample and extend to the base, the freezing pipes are arranged parallel to the extension direction of the shaft, and the plurality of freezing pipes are arranged at the periphery of the shaft; The monitoring device includes a plurality of vibration sensors, which are arranged radially and longitudinally along the outer side of the blasting surface, and are used to monitor the vibration propagation law during frozen soil blasting; The freezing device further comprises a refrigeration device, the refrigeration device is connected to the freezing pipe, and the refrigeration device is used to control the freezing temperature of the frozen soil sample; There are four freezing pipes, and the four freezing pipes are evenly arranged along the circumference of the shaft wall adjacent to the shaft; The barrel body comprises two half barrel bodies, and the two half barrel bodies are fastened and connected by connecting bolts; A plurality of bolt fixing blocks are evenly arranged on both sides of the half barrel body in the longitudinal direction, and the connecting bolts are used to fix and connect the two half barrel bodies through the bolt fixing blocks.

2. The vertical shaft frozen soil blasting model test system according to claim 1, characterized in that: The monitoring device further comprises a plurality of first strain gauges and a plurality of second strain gauges, wherein the plurality of first strain gauges are arranged along the longitudinal direction of the shaft wall, and the plurality of second strain gauges are arranged along the longitudinal direction of the freezing pipe; The first strain gauge and the second strain gauge are connected to a dynamic strain gauge through a data signal line, and the dynamic strain gauge is used to perform dynamic strain test and vibration test on the shaft wall and the freezing pipe; The monitoring device also includes a pressure box and a displacement meter, which are respectively connected to a static monitor via data signal lines. The static monitor is used to monitor the convergence deformation of the shaft wall and the displacement and deformation of the frozen soil sample during blasting excavation.

3. The vertical shaft frozen soil blasting model test system according to claim 2, characterized in that: The test system also includes a data acquisition instrument, which is connected to the vibration sensor via a data signal line and is used to collect vibration data monitored by the vibration sensor.

4. The vertical shaft frozen soil blasting model test system according to claim 1, characterized in that: The top cover and the base are both disc-shaped, and the outer diameters of the top cover and the base are both larger than the outer diameter of the barrel body; The size of the top cover is the same as that of the base; The barrel body and the top cover are fastened together by connecting bolts, and the barrel body and the base are fastened together by connecting bolts; a plurality of bolt fixing blocks are arranged on the sides of the top and bottom of the barrel body along the circumferential direction, and the connecting bolts fix the top end of the barrel body to the top cover through the bolt fixing blocks, and the connecting bolts fix the bottom end of the barrel body to the base through the bolt fixing blocks.

5. The vertical shaft frozen soil blasting model test system according to claim 4, characterized in that: A rubber sleeve is arranged between the barrel body and the frozen soil sample, the rubber sleeve is adhered to the inner wall of the barrel body, and an oil pressure cavity is formed inside the rubber sleeve; The rubber sleeve is connected with an oil injection device, and the oil injection device injects oil into the oil pressure cavity to apply circumferential pressure to the frozen soil sample through the oil pressure; The oil filling device includes an oil filling port and an oil delivery pipe. The oil filling port passes through the inner and outer walls of the barrel body and is connected to the oil pressure chamber of the rubber sleeve. One end of the oil delivery pipe is connected to the input end of the oil filling port, and the other end is connected to a throttle valve.

6. The vertical shaft frozen soil blasting model test system according to claim 1, characterized in that: A handle is provided on the outer wall of the barrel, and the handle is used to lift the sample preparation device; The inner wall of the barrel is provided with scale lines, and the scale lines are used to mark the volume of the sample preparation device.

7. The vertical shaft frozen soil blasting model test system according to claim 1, characterized in that: A plurality of legs are arranged below the base along the circumferential direction, and the legs are used to support the sample preparation device; The number of the legs is four, and the four legs are evenly arranged along the circumferential direction of the base; The supporting legs are steel pipe supporting legs.

8. A method for using the vertical shaft frozen soil blasting model test system according to any one of claims 1 to 7, characterized in that: The method of use comprises the following steps: Step S1, adjusting the moisture content according to the density of the pre-compacted sample, adding the sample into the inner cavity of the sample preparation device in multiple times, freezing it through a freezing tube after layered compaction, and obtaining a frozen soil sample; Step S2, drilling holes in the frozen soil sample within the vertical shaft and arranging detonators and explosives to simulate different blasting schemes; Step S3, applying axial pressure and circumferential pressure to the frozen soil sample to simulate the ground stress of the frozen soil sample under different excavation conditions, blasting the frozen soil in the middle shaft to simulate excavation, and monitoring and collecting blasting vibration data during the blasting process.

Images