A visual test device for simulating the autonomous upward floating of a shield tail synchronous grouting segment

Abstract

The application provides a kind of visual test device for simulating shield tail synchronous grouting segment autonomous floating, including soil tank, segment model, floating coordination system, synchronous grouting system, data detection system.Segment model is square steel cylinder, which can be internally watered to adjust its weight;Floating coordination system uses telescopic air rubber capsule to realize autonomous floating of segment model, and synchronous grouting system uses waterproof rubber film to be pasted at the connection between shield shell and soil tank, to avoid grout leakage after shield shell is pulled out.The patent is actually operated, the shield shell is pulled out from the soil tank at a constant speed by the synchronous grouting system, the shield tail gap is formed, the real shield tail synchronous grouting process is simulated;Autonomous floating of segment model is realized by floating coordination system, which is closer to engineering practice, and effectively solves the problem of grout leakage at the segment floating and shield tail gap, providing a scientific basis for segment floating amount prediction during shield tunnel shield tail synchronous grouting.

Description

Technical Field

[0001] This invention belongs to the field of synchronous grouting in shield tunnels, and specifically relates to a visual experimental device for simulating the autonomous floating of synchronous grouting segments at the shield tail. Background Technology

[0002] During shield tunneling, due to the thickness of the shield shell, a tail gap appears between the tunnel segments and the soil after the shield shell exits. To ensure the stability of the lining structure, synchronous grouting is required to fill the tail gap. During the filling process, due to the diffusion and solidification of the grout, the tunnel segments may float to some extent, affecting the stress on the lining structure. To date, many scholars have studied the tunnel segment floating problem caused by synchronous grouting during shield tunneling.

[0003] To simulate the floating of tunnel segments during synchronous grouting, Ding Wantao, Wang Han, and others used cylindrical components to simulate both the tunnel and segment models. They simulated the segment exiting the shield tail stage during tunnel excavation by controlling the air pressure in the rubber bladder outside the segment model. Simultaneously, grout was injected into the rubber bladder via grouting pipes for synchronous grouting. A pulley connecting the segment and tunnel models was used to simulate the segment's upward floating motion under stress. Zhang Liankai connected the segment model to a weighing sensor using a connecting rod, and inferred the buoyancy force by observing changes in sensor values ​​during grout immersion. For simulating grout penetration during synchronous grouting, Yang Xiaohu, Wang Yingtie, and others provided a similar model test method for synchronous grouting in shield tunnels. This method uses a pipe ring between two pipes of different diameters to simulate the shield tail gap, effectively simulating arbitrary soft soil conditions, tunnel dimensions, construction excavation processes, and synchronous grouting parameters, and effectively observing grout flow and penetration. For monitoring the surface portion during synchronous grouting, Ding Wenqi, Zhao Tianchi, and others used a pull-out device to connect the grouting pipe to simulate the synchronous grouting process of shield tunneling. The front of the model box was made of transparent material, and cameras and grids were installed at the front and back to observe the filling process and flow state of the grout in the gaps during the grouting process, as well as the settlement and heave of the model soil. However, grout leakage is prone to occur during the pull-out process.

[0004] In the prior art, Chinese invention patent application "A Shield Tunnel Synchronous Grouting Similar Model Test System and Method" (Patent No.: 202010975844.3), Chinese utility model patent application "A Shield Tunnel Synchronous Grouting Simulation Test System" (201620339567.6), and Chinese utility model patent application "A Shield Construction Synchronous Grouting Simulation Test Platform" (Patent No.: 201520421960.5) all provide test benches for simulating the synchronous grouting process of shield tunnels. By simulating tunnel models and segment models with circular components, they have conducted in-depth discussions on the grout filling process and filling mechanism. Some devices can monitor the floating amount of segments. However, these test devices all scale down the segment models, and the grout cannot be configured equivalently, so they cannot simulate the actual stress of segment floating. This utility model patent selects a local micro-element at the bottom of the tunnel segment for simulation, providing a test platform that can realistically reproduce the synchronous grouting process on a proportional scale. It realizes the simulation of the tunnel segment floating during synchronous grouting, and makes a relatively accurate measurement of the grout diffusion and solidification process as well as the buoyancy force on the tunnel segment. It effectively solves the grout leakage problem that occurs at the shield exit and tunnel segment floating points of existing test platforms, filling the gap in this field. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing test devices, such as the easy leakage of grout at the point where the segments float and the shield tail detaches during the test, and the need for manual adjustment of the segment floating amount. This invention provides a visual test device for simulating the autonomous floating of segments during synchronous grouting at the shield tail.

[0006] The technical solution of this invention is as follows:

[0007] The purpose of this invention is to provide a visual experimental device for simulating the autonomous floating of tunnel segments during synchronous grouting at the tail of a shield. The device is characterized by comprising a soil box, a tunnel segment model, a floating adjustment system, a synchronous grouting system, and a data monitoring system. The soil box includes two steel plates, two transparent plates, and a sliding rail on one side of the soil box. The steel plates are ribbed and connected by bolts. The sliding rail is fixed to one side of the soil box by bolts and is higher than the soil box. The tunnel segment model is a square steel cylinder with a piezoelectric thin-film sensor at the bottom to monitor the stress distribution on the pressure surface. The tunnel segment model is installed directly above the soil box, and its side is connected to the sliding rail on the side of the soil box. The floating coordination system includes a ring of air rubber bladders, vertically installed between the tunnel segment and the soil box, with its upper and lower ends respectively attached to the periphery of the pressure sensor at the bottom of the tunnel segment model and the upper edge of the soil box. The synchronous grouting system includes a... The horizontally sliding shield shell and grouting system include a shield machine shell, a waterproof rubber membrane, a slide rail, a crank handle, a screw, a sliding steel frame, and a supporting steel frame. The shield machine shell is a square steel cylinder placed on the slide rail, with its front end connected to the sliding steel frame. A pulley is installed at the bottom of the sliding steel frame and connected to the slide rail. The slide rail is placed on the supporting steel frame. The crank handle is connected to the sliding steel frame via the screw. By rotating the crank handle, the screw retracts, causing the sliding steel frame to move horizontally. This allows the shield machine shell to be pulled out from an opening on one side of the soil box, forming a tail gap. A sufficiently elastic waterproof rubber membrane is affixed inside the soil box to cover this opening. The membrane adheres to the tail surface of the shield machine shell, and grouting holes are provided. The grouting system includes a grouting pump and grouting pipes. As the shield shell slides, grout is simultaneously injected into the tail gap through the grouting pipes.

[0008] Furthermore, the device is used for synchronous grouting construction at a local single grouting pipe at the bottom of the shield during the synchronous grouting process of the shield. The shield shell is pulled out of the soil box by the shield tail release system to simulate the shield tail propulsion process. At the same time, a shield tail gap is formed between the segment model and the soil. The synchronous grouting process of shield tail release is simulated through the grouting holes on the shield shell in the grouting system. It can simulate the autonomous floating process of the segment under different grouting pressures, different grouting volumes, and different grout types.

[0009] Preferably, the soil box is a combination structure of glass plate and steel plate, used to observe the diffusion and solidification process of grout during synchronous grouting, and adopts a detachable baffle structure for repeated testing.

[0010] Preferably, to ensure that no grout leakage occurs when the shield tail is disengaged, a sufficiently elastic waterproof rubber film is affixed to the contact area between the shield tail surface and the soil box.

[0011] Preferably, to ensure that the segments can float autonomously under the action of grout, the four sides of the bottom of the segments are connected to the soil box by a ring of air rubber bladders, and the guide rails on the side of the soil box are coated with lubricating oil to ensure their sensitivity.

[0012] Preferably, to ensure that the buoyancy of the tunnel segments matches the actual project conditions, the synchronous grouting slurry and the backfill soil of the soil box should be the same as those in the actual project.

[0013] Preferably, to ensure that the diffusion of the grout during synchronous grouting is easy to observe and the extent of grout penetration into the soil layer is easy to identify, a colorant is added to the synchronous grout to form a clear and identifiable contrast.

[0014] The buoyancy test of shield tunneling synchronous grouting using the aforementioned device includes the following steps:

[0015] Step 1, Assemble the soil box: Assemble the steel plate and the transparent plate together and fix them with bolts. Apply sealant to the gaps and line the inside with plastic wrap.

[0016] Step 2, Soil filling: Fill the soil excavated by the shield tunneling machine into the soil box, fill and compact it in layers, and make the filling height level with the bottom surface of the shield tunneling machine shell;

[0017] Step 3: Install the segments: Connect the segments to the side guide rails of the soil box, and fit a ring of air rubber bladders around the four sides of the bottom surface of the segments to connect with the four sides of the upper surface of the soil box to prevent grout leakage.

[0018] Step 4: Connect the grouting pump to the grouting hole, set the grouting pressure, grouting volume, segment weight and tunneling speed according to the test requirements, turn on the switch to start the test. During the test, turn the crank handle and use the screw to retract to pull out the shield shell, ensuring that the shield shell moves forward at a uniform speed. Collect relevant data through the piezoelectric thin film sensor and observe the grout diffusion and infiltration process through the transparent baffle.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] 1. Wide range of applications and strong scalability. The shield tunneling synchronous grouting simulation test conducted by this invention allows for the filling of different types of backfill according to the tunneling soil layer, and the grouting volume, grouting pressure, advance speed, and grout type can be changed according to the test requirements. It can detect the buoyancy force of the grout on the tunnel segments during synchronous grouting, and observe the diffusion and penetration process of the grout, simulating the shield tunneling synchronous grouting and tunnel segment buoyancy process under different working conditions.

[0021] 2. High economic benefits. By replacing different modules, most of the synchronous grouting simulation segment floating tests during shield tail release can be met, and the modules are reusable, making it economical and environmentally friendly.

[0022] 3. The device is compact and easy to process, assemble and clean. Attached Figure Description

[0023] Figure 1 This is a structural schematic diagram of an example of the present invention;

[0024] Figure 2 yes Figure 1 Enlarged view of section A in the middle;

[0025] Figure 3 This is a schematic diagram of the bottom of the tube segment of the present invention;

[0026] Figure 4 This is a schematic diagram showing the connection between the grouting pump and the grouting hole. Detailed Implementation

[0027] A visual experimental device for simulating the autonomous floating of shield tail synchronous grouting segments was implemented as follows: Figures 1-4 The structure includes a soil tank 1, a segment model 5, a shield outer shell 6, a hand-cranked propulsion platform 7, and a grouting pump. The segment model 5 is a square steel cylinder. The bottom four sides of the shield segment model 5 are connected to the upper edge of the soil tank 1 via a ring of air rubber bladders 3, allowing the segment model 5 to float independently and preventing grout leakage. One side of the shield segment model 5 is mounted in a side rail 4 of the soil tank 1. The segment model 5 is welded from steel. The weight of the segment is adjusted by injecting water into the opening 12 at the top of the segment. A piezoelectric thin-film sensor 10 is laid at the bottom of the segment model 5 to monitor the stress distribution across the entire pressure surface. The soil tank 1 includes two transparent plates 14 and two steel plates, connected by grooves and bolts. After assembly, sealant is applied to the gaps to prevent grout leakage. The side of the soil tank 1 is connected to the rail 4 by bolts. The horizontally sliding shield shell includes a tunnel boring machine (TBM) shell 6, a supporting steel frame 7, a crank handle 9, and a sliding rail 8. The tail face of the TBM shell 6 is connected to the side opening of the soil tank 1. A waterproof rubber film 14 is affixed to this connection. The film 14 is adhered to the inside of the soil tank 1 on all four sides. The film 14 covers the tail face of the TBM shell 6 and has grouting holes 13 cut out at corresponding positions. The remaining contact parts are adhered to the tail face of the TBM shell 6 to prevent grout leakage when the tail is removed. The TBM shell 6 is manually propelled. Rotating the crank handle 9 drives the screw 16 to retract, thereby causing the sliding support 11 to slide horizontally, pulling the TBM shell 6 out of the soil tank 1 through the sliding rail 8, forming a tail gap for synchronous grouting. The synchronous grouting system includes grouting holes 13, grouting pipes 16, and a grouting pump 15. The grouting pipes 16 connect the grouting pump 15 to the grouting holes 13 at the front end of the TBM shell 6, and grouting is performed using the pressure of the grouting pump 15.

[0028] The steel plate in soil box 1 is assembled with the transparent plate 17 and fixed with bolts. Sealant is applied to the gaps, and plastic wrap is laid inside to form a watertight, sealed space to prevent water and grout leakage. Soil excavated from the shield tunnel is filled into soil box 1, layered and compacted, with the fill height 2 level with the bottom surface of the shield shell 6. The segment model 5 is connected to the side rail 4 of soil box 1. The two ends of the air rubber bladder 3 are respectively attached to the periphery of the piezoelectric film sensor 10 at the bottom of the segment model 5 and the upper edge of soil box 1, thus meeting the requirements of the segment... To ensure the autonomous floating of model 5 and prevent grout leakage during the floating of segment model 5, the grouting hole 13 is connected to the grouting pump 15. The grouting pressure, grouting volume, segment weight, and tunneling speed are set according to the test requirements. The switch is turned on to start the test. During the test, the shield shell 6 is kept moving forward at a constant speed. Relevant data are collected by the piezoelectric film sensor 10 laid at the bottom of segment model 5. The floating amount of segment model 5 is observed through the slide rail 4 on the side of the soil box 1. The grout diffusion and seepage process is observed through the transparent baffle 16.

[0029] After the test begins, power is provided by rotating the crank handle 9, which pulls the shield machine shell 6 out of the soil box 1 at a certain speed through the auger. A tail gap is formed between the upper surface of the backfill 2 and the segment model 5. The specific speed can be adjusted according to actual needs. At the same time as the shield machine shell 6 is detached, the grouting pipe 16 connects the grouting pump 15 to the grouting hole 13 at the front end of the shield shell 6. The grouting pump 15 is used to perform synchronous grouting to simulate synchronous grouting during the tail detachment process. The synchronous grouting volume and grout type can be adjusted according to actual needs. The grout penetration and diffusion process can be observed through the transparent plate 17 in the soil box 1. The pressure of the synchronous grouting slurry on the segment model 5 can be monitored by the piezoelectric thin film sensor 10 laid at the bottom. The floating amount of the segment model 5 can be displayed by the scale bar on the slide rail 4 on the side of the soil box 1.

[0030] Matters not covered in this invention are common knowledge.

[0031] The above embodiments are merely illustrative of the technical concept and features of the present invention, intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly, and should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A visual experimental device for simulating the autonomous floating of shield tail synchronous grouting segments, characterized in that: The system includes a soil box (1), a segment (5), a floating coordination system, a synchronous grouting system, and a data monitoring system. The soil box (1) includes two steel plates, two transparent plates (17), and a slide rail (4) on one side of the soil box (1). The steel plates are ribbed and connected by bolts. The slide rail (4) is fixed to one side of the soil box (1) by bolts and is higher than the soil box (1). The segment (5) is a square steel cylinder with a piezoelectric thin film sensor (10) laid at the bottom to monitor the stress distribution on the pressure surface. The segment (5) is installed directly above the soil box (1) and its side is connected to the slide rail (4) on the side of the soil box (1). The upper part of the segment (5) is provided with an opening (12), which is a channel for injecting water into the interior of the segment (5); the floating coordination system includes a ring of retractable air rubber bladders (3), which are vertically installed between the segment (5) and the soil box (1), with the upper and lower ends respectively attached to the periphery of the piezoelectric film sensor (10) at the bottom of the segment (5) and the upper edge of the soil box (1); the synchronous grouting system includes a horizontally sliding shield shell and a grouting system, the horizontally sliding shield shell includes a shield machine shell (6), a waterproof rubber film (14), a slide rail (8), and a crank handle. (9), screw (18), sliding steel frame (11), supporting steel frame (7), the shield machine shell (6) is a square steel cylinder, placed on the slide rail (8), the front end is connected to the sliding steel frame (11), the bottom of the sliding steel frame (11) is installed with pulleys and connected to the slide rail (8), the slide rail (8) is placed on the supporting steel frame (7), the crank (9) is connected to the sliding steel frame (11) through the screw (18), by turning the crank (9), the screw (18) is driven to retract, thereby causing the sliding steel frame (11) to move horizontally, so that the shield machine shell (6) moves from the soil box (1) side Pull out the opening to form a shield tail gap. A waterproof rubber film (14) is glued inside the soil box to cover the opening. The film (14) is attached to the shield tail surface of the shield machine shell (6) and a grouting hole (13) is left. The grouting system includes a grouting pump (15) and a grouting pipe (16). As the shield machine shell (6) slides, the grouting pipe (16) injects grout into the shield tail gap simultaneously. The bottom side of the segment (5) is connected to the soil box (1) by an air rubber bladder (3) to avoid grout leakage between the segment (5) and the inner wall of the soil box (1), and realizes the vertical displacement of the segment to simulate the floating of the segment.

2. The visual experimental device for simulating the autonomous floating of synchronous grouting segments at the shield tail as described in claim 1, characterized in that: A waterproof rubber film (14) is affixed to the contact surface between the shield machine shell (6) and the soil box (1) to prevent grout leakage from the gap between the shell and the box wall during the forward movement of the shield machine shell (6).

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