Model box test device for simulating shield grouting and test method thereof

Abstract

The invention discloses a model box test device for simulating shield grouting, which comprises a model box, a shield model, a grouting device, a traction system, an image acquisition system and a displacement monitoring system, the shield model containing a grouting hole and the grouting system are arranged in the model box, the grouting device is connected with the grouting hole of the shield model through a grouting pipe, and the traction system is connected with the image acquisition system. The traction system is connected to the front portion of the shield model, the image acquisition system is placed on the outer side of the model box, located on the side face of the shield model and used for acquiring slurry movement tracks, the displacement monitoring system comprises a displacement sensor arranged on the upper portion of the model box, and a movable laser is arranged on the side, opposite to the rear portion of the shield model, of the model box. The device can directly obtain results after visually copying actual conditions, complex full-size tests do not need to be carried out on the spot, and the device is economical and has more real test results compared with a numerical model; various variables can be set, the requirement for researching various influence factors by adopting one device is met, and the research range is diversified.

Description

Technical Field

[0001] The invention relates to the field of tunnels and underground engineering, and in particular to a model box test device for simulating shield grouting and a test method thereof. Background Art

[0002] In recent years, with the improvement of people's living standards, the tunnel industry has developed rapidly, especially the construction and research of long and large tunnels in highway tunnels. At present, urban tunnel construction widely adopts the shield method with strong adaptability to geological conditions and fast construction speed. This method can greatly alleviate the urban traffic congestion caused by construction, and also brings convenience to the maintenance and inspection of municipal facilities. In this context, domestic and foreign academic and engineering circles are paying close attention to tunnel construction technology. The shield method has become a very common technology in developed countries and has gradually been widely used in developing countries. Thanks to its strong adaptability to geological conditions and fast construction speed, there are multiple data that need to be focused on during the construction of the shield, and these data are affected by many factors. In-depth research on the impact of different factors on shield tunnels has important guiding significance and reference value.

[0003] Through the literature search of current technologies, it is found that the research on shield grouting mainly includes theoretical research, numerical simulation and indoor tests. The indoor test equipment includes:

[0004] Tongji University's invention patent (application publication number CN107120120A) provides a frame-mounted shield tunnel wall thickness grouting detection equipment. The test device includes a frame-mounted automatic transmission device, an air-coupled ground-penetrating radar, and intelligent processing and analysis software for the grouting behind the wall. Through the integration of software and hardware, the equipment realizes real-time visual detection of the grouting layer behind the wall during the shield construction process. The frame-mounted automatic transmission device mainly includes tracks, synchronous belts, transmission mechanisms, servo extensions and drives, and reducers; by carrying a new air-coupled radar detection device and installing it on the first section of the shield frame, the shield grouting body is circumferentially detected and the grouting body is visualized in layers as the shield advances. However, the test cost is too high, the test equipment is complex, and it is affected by the complex environment in the tunnel. The radar will encounter various interference signals when collecting data, and the collected data will vary greatly. Some interference data will even completely cover up the valid data, resulting in misjudgment of poor geological bodies and inaccurate results.

[0005] The utility model patent (application number 202020903506.4) of PowerChina Huadong Survey and Design Institute Co., Ltd. relates to a model test device for a subway shield tunnel in a soft soil area to pass under an existing tunnel in parallel. The purpose of this utility model is to provide a model test device for a subway shield tunnel in a soft soil area to pass under an existing tunnel in parallel, which has a simple structure, is easy to make and easy to operate. The device has a model box, and one or more rows of vertically arranged openable and closable starting holes are formed on the end surface of one end of the model box, and one or more rows of vertically arranged openable and closable receiving holes are formed on the end surface of the other end of the model box; the model box is filled with soft soil, and a shield model I as an existing tunnel is built in the soft soil, and the shield model I extends from the starting hole to the receiving hole; a shield model II is arranged in the model box and below the shield model I, and a driving mechanism that can drive it to move from the starting hole to the receiving hole is provided on the shield model II; a displacement meter, a strain gauge and an earth pressure box are installed on the shield model I. However, the visualization effect of the device is not ideal. Due to the limited installed equipment, the information obtained from the device is also very simple.

[0006] The invention patent (application publication number CN108918670A) of Nanning China Railway Guangfa Railway Equipment Co., Ltd. discloses a real-time grouting detection platform for shield tunnel construction, including a detection bracket, a transition bracket and a grouting detection device. The detection bracket is arranged on the shield machine frame, the transition bracket is installed on the detection bracket and can move on the detection bracket, the grouting detection device is fixed on the transition bracket, and the grouting detection device can detect the grouting parameters behind the segment wall. During the advancement of the shield machine, the detection bracket moves with the shield machine, and the grouting detection device is installed on the transition bracket. In addition, the transition bracket can move on the detection bracket, so that the grouting detection device can detect the slurry behind the segment wall in real time. When the mobile detection finds that the filling is not ideal, the parameters can be adjusted in time to improve the construction quality. However, the visualization degree of the device is not ideal, and it is impossible to synchronously detect and detect the grouting conditions of each point.

[0007] Based on the above situation, the present invention proposes a model box test device and a test method for simulating shield grouting to effectively solve the problems of unsatisfactory visualization effect, limited and single research scope, etc. Summary of the invention

[0008] In order to solve the problems existing in the background technology, the present invention provides a model box test device and a test method thereof for simulating shield grouting.

[0009] The present invention adopts the following technical solution:

[0010] A model box test device for simulating shield grouting, comprising a model box, a shield model, a grouting device, a traction system, an image acquisition system and a displacement monitoring system. A shield model with grouting holes and a grouting system are placed in the model box. The grouting device is connected to the grouting holes of the shield model through a grouting pipe. The traction system is connected to the front of the shield model. The image acquisition system is placed on the outside of the model box and on the side of the shield model for collecting the slurry movement trajectory. The displacement monitoring system comprises a displacement sensor arranged on the upper part of the model box. A movable laser is arranged on one side of the model box relative to the rear of the shield model.

[0011] Furthermore, the model box includes a box body formed by splicing fixed brackets, the model box has no top cover, and the other five sides are all made of transparent materials. The transparent material can be acrylic or tempered glass, so as to facilitate the observation of the slurry diffusion phenomenon.

[0012] Furthermore, the shield model is formed by splicing multiple ring segment models, multiple grouting holes are arranged on both sides of the forward end of the shield model, and segments are arranged in the opposite direction of the forward movement of the shield model to simulate the segment assembly after the shield tunneling begins.

[0013] Furthermore, the grouting device includes a motor, a slurry storage barrel, a stirring rod, a pressure pipe, a grouting pipe and a pressurized air pump. The slurry storage barrel is provided with a stirring rod, the slurry storage barrel is provided with a barrel cover, a motor and an upper pressure pipe are provided above the barrel cover, the pressure pipe is connected to the pressurized air pump, and a grouting pipe connected to the grouting hole of the shield model is provided at the lower part of the grouting barrel.

[0014] Furthermore, the pressurized air pump is provided with a pressure gauge, and the grouting pipe is provided with a pressure gauge at one end of the slurry storage barrel.

[0015] Furthermore, the pressurized air pump includes a force ring and a hydraulic jack.

[0016] Furthermore, the barrel cover is fixed to the slurry storage barrel by bolts. A total of four grouting holes are set, evenly distributed at the shield tail. During the uniform speed of the shield, according to the required grouting amount, each valve is opened, and the shield tail performs synchronous grouting. Under the operation of the pressurized air pump, the grouting system grouts the shield tunnel through the grouting pipe.

[0017] Furthermore, the traction system includes two scaled constant velocity loaders. At the beginning of the test, the shield model is loaded with constant velocity to simulate shield tunneling.

[0018] Furthermore, a test method of a model box test device for simulating shield grouting comprises the following steps:

[0019] Step 1: Install the fixed bracket, fix the model box, debug the monitoring system and related components of the loading system, calibrate the basic parameters of the hydraulic jack, calibrate the basic parameters of similar soil and lining materials, and place the shield model in the model box;

[0020] Step 2: Fill the soil to one-fold depth, cover the loading plate and pressurize with a jack, and measure the soil weight to 18KN / m 3 , arrange the pressure box, continue to fill 0.5D thickness, pressurize as mentioned above, arrange the pressure box at the same time, continue to fill 1D, and then arrange the pressure box;

[0021] Step 3: Simulate the buried depth and fill to the specified height, perform the initial consolidation by jack loading, and let it stand for 24 hours. Pour the prepared slurry into the slurry storage barrel and turn on the agitator in the slurry storage barrel;

[0022] Step 4: Arrange several displacement meters in the horizontal and vertical directions to monitor the surface settlement trough and the vertical settlement of the surface. Insert the strain gauge lead wire and the grouting pipe into the segment in advance, and carry out radial pressure monitoring, annular pressure monitoring, horizontal settlement monitoring and vertical settlement monitoring of the surface by fine earth pressure box.

[0023] Step 5: The scaled isokinetic loading instrument moves at a uniform speed to simulate the forward excavation of the shield tunnel. Turn on the pressurized air pump switch. When the pressure gauge reading on the slurry storage barrel reaches the set value, open the valve and inject grouting into the grouting holes in the shield model through the grouting pipe to achieve grouting behind the wall. According to the pressure gauge reading, adjust the air pump pressure at any time to keep the pressure in the barrel at a stable value. After the surface settlement is stable (about 20 minutes, the slurry solidification time is 40 to 50 minutes), splice a ring of segments, continue to move forward 2 cm, synchronously inject grouting, and shut down for stability. This cycle realizes the excavation and grouting support process of the shield tunnel, and records and observes the excavation and grouting support process.

[0024] Step 6: The laser emits laser to form a speckle section, and the image acquisition system is used to capture the entire grouting process. When the grouting reaches the set time, the valve and the pressurized air pump are closed. After the pressure dissipates, the grouting hose between the pressurized air pump and the slurry storage barrel is removed, the slurry in the slurry storage barrel is poured out and cleaned, and the images and data collected in the test are analyzed.

[0025] The present invention provides a model box test device for simulating shield grouting and a test method thereof: the device controls the main test parameters without being restricted or affected by environmental conditions, and is convenient for changing the test parameters for comparative tests. The entire site is reduced in proportion, and various variables are controlled and then recorded to finally obtain the experimental results. The results can be directly obtained after intuitively replicating the actual situation, and there is no need to conduct complex full-scale tests on site. The device is economical and has more realistic test results than numerical models.

[0026] The model box of this model test is relatively large. The large-sized model can better reflect the stress and deformation of the prototype. The larger the size, the easier it is to control the similarity ratio of the model material.

[0027] The device can be set with a variety of variables to meet the needs of using one device to study a variety of influencing factors, and the research scope is diverse. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The overall structure of the present invention is shown in FIG. Figure 1 ;

[0029] Figure 2 The overall structure of the present invention is shown in FIG. Figure 2 ;

[0030] Figure 3 It is a schematic diagram of the loading system of the present invention;

[0031] Figure 4 It is a schematic diagram of the grouting system of the present invention;

[0032] Figure 5 The pressure box arrangement around the tunnel of the present invention;

[0033] Figure 6 This is the arrangement of the surface displacement meter of the present invention.

[0034] The serial numbers marked in the figure represent the following in turn: 1. Computer, 2. Displacement sensor, 3. Fixed bracket, 4. Camera, 5. Movable laser, 6. Constant-speed loader with scale, 7. Shield model, 8. Grouting hole, 9. Model box, 10. Segment, 11. Data connection line, 12. Grouting system, 13. Grouting pipe, 14. Pressurized air pump, 15. Pressure gauge, 16. Bolt, 17. Motor, 18. Bucket cover, 19. Slurry storage bucket, 20. Stirring rod, 21. Pressurized pipe, 22. Force ring, 23. Hydraulic jack. DETAILED DESCRIPTION

[0035] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0036] Refer to the attached Figure 1-6 A model box test device for simulating shield grouting, comprising a model box, a shield model, a grouting device, a traction system, an image acquisition system and a displacement monitoring system. A shield model with grouting holes and a grouting system are placed in the model box. The grouting device is connected to the grouting holes of the shield model through a grouting pipe. The traction system is connected to the front of the shield model. The image acquisition system is placed on the outside of the model box and on the side of the shield model for collecting the slurry movement trajectory. The displacement monitoring system comprises a displacement sensor arranged on the upper part of the model box. A movable laser is arranged on the side of the model box relative to the rear of the shield model.

[0037] The displacement monitoring system also includes a data connection line and a computer. After the synchronous grouting starts, the soil settlement is monitored and uploaded to the computer through the data connection line to draw an image of the displacement that changes with time.

[0038] The model box includes a box body formed by splicing fixed brackets, the model box has no top cover, and the other five sides are all made of transparent materials. The transparent material can be acrylic or tempered glass, so as to facilitate the observation of slurry diffusion phenomenon.

[0039] Preferably, the model box is made of transparent tempered glass material (5 cm thick, ensuring that the surface deformation is less than 0.2 mm, and a circular hole with a diameter of 80 mm is opened on the front of the model), the periphery is fixed with angle steel, and the joints are fully bonded with glue. The outer shell is an alloy square steel support frame.

[0040] The shield model is formed by splicing multiple ring segment models, multiple grouting holes are arranged on both sides of the forward end of the shield model, and segments are arranged in the opposite direction of the forward movement of the shield model to simulate the segment assembly after the shield excavation begins.

[0041] The grouting device includes a motor, a slurry storage barrel, a stirring rod, a pressure pipe, a grouting pipe and a pressurized air pump. The slurry storage barrel is provided with a stirring rod, the slurry storage barrel is provided with a barrel cover, a motor and an upper pressure pipe are provided above the barrel cover, the pressure pipe is connected to the pressurized air pump, and a grouting pipe connected to the grouting hole of the shield model is provided at the lower part of the grouting barrel.

[0042] The pressurized air pump is provided with a pressure gauge, and the grouting pipe is provided with a pressure gauge at one end of the slurry storage barrel.

[0043] The pressurized air pump comprises a force ring and a hydraulic jack.

[0044] The barrel cover is fixed to the slurry storage barrel by bolts. A total of four grouting holes are set, evenly distributed at the shield tail. During the shield advances at a uniform speed, the valves are opened according to the required grouting amount to perform synchronous grouting. Under the operation of the pressurized air pump, the grouting system grouts the shield tunnel through the grouting pipe.

[0045] The image acquisition system includes a movable laser and a camera. During synchronous grouting, the laser emits laser light on a certain plane, and the camera can capture the slurry movement trajectory on the plane. By moving the laser, the situation on different planes can be observed, thus forming a three-dimensional visual grouting image.

[0046] The system can also include a contact monitoring system consisting of a 2t jack oil pressure gauge, a pressure ring stress meter, a strain gauge, a pressure box, a programmable static resistance strain gauge, and a micrometer; a non-contact monitoring system consisting of a movable laser and a camera. The camera takes process pictures, and each frame of the picture at different time periods is taken out and processed with PIV view2C software to obtain a two-dimensional vector diagram and cloud map of soil particle movement.

[0047] The traction system includes two scaled constant velocity loaders. At the beginning of the test, the shield model is loaded with constant velocity to simulate shield tunneling.

[0048] The maximum settlement (pixel) of each working condition obtained by PIV view2C processing is shown in Tables 1 and 2.

[0049]

[0050] Table 1

[0051]

[0052] Table 2

[0053] In order to better observe the microscopic changes in the data, the pixel conversion ratio was adjusted, that is, 20 pixels represent 0.1 mm: the above data were compared with the maximum settlement data of contact observation using a displacement meter to obtain the discrete deviation percentage, as shown in Table 3-4. Table 3 shows the longitudinal settlement of rough tunnel excavation at different cover-span ratios, and Table 4 shows the longitudinal settlement of the surface after shield excavation and support.

[0054]

[0055]

[0056] Table 3

[0057]

[0058]

[0059] Table 4

[0060] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A model box test device for simulating shield grouting, characterized in that: The invention comprises a model box, a shield model, a grouting device, a traction system, an image acquisition system and a displacement monitoring system. The shield model with grouting holes and the grouting system are placed in the model box. The grouting device is connected to the grouting holes of the shield model through a grouting pipe. The traction system is connected to the front of the shield model. The image acquisition system is placed on the outside of the model box and on the side of the shield model for collecting the movement trajectory of the slurry. The displacement monitoring system comprises a displacement sensor arranged on the upper part of the model box. A movable laser is arranged on the side of the model box relative to the rear part of the shield model.

2. A model box test device for simulating shield grouting according to claim 1, characterized in that: The model box includes a box body formed by splicing fixed brackets, the model box has no top cover, and the other five sides are all made of transparent materials. The transparent material can be acrylic or tempered glass, so as to facilitate the observation of slurry diffusion phenomenon.

3. A model box test device for simulating shield grouting according to claim 1, characterized in that: The shield model is formed by splicing multiple ring segment models. Multiple grouting holes are arranged on both sides of the forward end of the shield model, and segments are arranged in the opposite direction of the forward direction of the shield model.

4. A model box test device for simulating shield grouting according to claim 1, characterized in that: The grouting device It includes a motor, a slurry storage barrel, a stirring rod, a pressure pipe, a grouting pipe and a pressurized air pump. The slurry storage barrel is provided with a stirring rod, the slurry storage barrel is provided with a barrel cover, a motor and an upper pressure pipe are provided above the barrel cover, the pressure pipe is connected with the pressurized air pump, and a grouting pipe connected to the grouting hole of the shield model is provided at the lower part of the grouting barrel.

5. A model box test device for simulating shield grouting according to claim 4, characterized in that: The pressurized air pump is provided with a pressure gauge, and the grouting pipe is provided with a pressure gauge at one end of the slurry storage barrel.

6. A model box test device for simulating shield grouting according to claim 4, characterized in that: The pressurized air pump comprises a force ring and a hydraulic jack.

7. A model box test device for simulating shield grouting according to claim 4, characterized in that: The barrel cover is fixed to the slurry storage barrel by bolts. A total of four grouting holes are set, evenly distributed at the shield tail. During the uniform forward movement of the shield, according to the required grouting amount, each valve is opened, and the shield tail performs synchronous grouting. Under the operation of the pressurized air pump, the grouting system grouts the shield tunnel through the grouting pipe.

8. The model box test device for simulating shield grouting according to claim 1, characterized in that: The traction system comprises two isokinetic loadometers with scales.

9. A test method for a model box test device for simulating shield grouting according to any one of claims 1 to 8, characterized in that: The following steps are involved: Step 1: Install the fixed bracket, fix the model box, debug the monitoring system and related components of the loading system, calibrate the basic parameters of the hydraulic jack, calibrate the basic parameters of similar soil and lining materials, and place the shield model in the model box; Step 2: Fill the soil to one-fold depth, cover the loading plate and pressurize with a jack, and measure the soil weight to 18KN / m 3 , arrange the pressure box, continue to fill 0.5D thickness, pressurize as mentioned above, arrange the pressure box at the same time, continue to fill 1D, and then arrange the pressure box; Step 3: Simulate the buried depth and fill to the specified height, perform the initial consolidation by jack loading, and let it stand for 24 hours. Pour the prepared slurry into the slurry storage barrel and turn on the agitator in the slurry storage barrel; Step 4: Arrange several displacement meters in the horizontal and vertical directions to monitor the surface settlement trough and the vertical settlement of the surface. Insert the strain gauge lead wire and the grouting pipe into the segment in advance, and carry out radial pressure monitoring, annular pressure monitoring, horizontal settlement monitoring and vertical settlement monitoring of the surface by fine earth pressure box. Step 5: The scaled isokinetic loading instrument moves at a uniform speed to simulate the forward excavation of the shield tunnel. Turn on the pressurized air pump switch. When the pressure gauge reading on the slurry storage barrel reaches the set value, open the valve and inject grouting into the grouting holes in the shield model through the grouting pipe to achieve grouting behind the wall. According to the pressure gauge reading, adjust the air pump pressure at any time to keep the pressure in the barrel at a stable value. After the surface settlement is stable, splice a ring of segments and continue to move forward 2 cm. Synchronously inject grouting and shut down for stability. This cycle realizes the excavation and grouting support process of the shield tunnel. Record and observe the excavation and grouting support process. Step 6: The laser emits laser to form a speckle section, and the image acquisition system is used to capture the entire grouting process. When the grouting reaches the set time, the valve and the pressurized air pump are closed. After the pressure dissipates, the grouting hose between the pressurized air pump and the slurry storage barrel is removed, the slurry in the slurry storage barrel is poured out and cleaned, and the images and data collected in the test are analyzed.

Images