Prefabrication device and method for large-span tunnel lining model in geomechanical model test

Abstract

This invention relates to a prefabrication device and method for large-span tunnel lining models in geomechanical model tests. The device comprises an inner mold, an outer mold, a bottom plate, a top plate, fixed columns, and a foam buffer layer. It can be manufactured from PVC boards, acrylic boards, and wooden boards using a laser engraving machine. This device and method are applicable to the tunnel lining pre-embedding method in geomechanical model tests. Specifically, the tunnel lining is first fabricated, and after the geomechanical model filler reaches a certain height, the tunnel lining is embedded, followed by the installation of a filler of a certain thickness. Finally, the loading, deformation, and stress monitoring processes are conducted. This invention can fabricate tunnel linings of different lengths, thicknesses, and flatness ratios according to research needs, solving the problem of difficult model lining fabrication. Furthermore, the device is simple in structure, easy to disassemble and reuse, and inexpensive, thus having broad application prospects.

Description

Technical Field

[0001] The invention belongs to the technical field of geomechanics, and in particular to a device and method for casting a lining-similar material into a special mold to prefabricate a secondary lining model of a tunnel in a geomechanics model test. Background Art

[0002] At present, my country is the country with the largest scale, the largest number and the fastest construction speed of tunnel projects in the world. Due to the uncertainty of influencing factors such as geological conditions, climatic conditions, support design parameters, building material characteristics and operation and maintenance conditions, a large number of tunnels in operation have suffered from lining cracks, falling blocks, arch uplift and other disasters that seriously affect the service performance and life of the tunnels, and even threaten the driving safety in the tunnels, causing serious consequences such as traffic blockage and casualties and adverse social impacts. At the same time, cracks in tunnel structures are often accompanied by water leakage, steel corrosion, frost damage and other phenomena. They are the most typical diseases during the operation of tunnel projects, which will aggravate the destruction process of tunnel lining structures, causing tunnels to need maintenance before reaching their designed service life, seriously affecting the normal operation of tunnels and structural durability. Therefore, it is indispensable to study the cracks in tunnel linings during operation and the disasters caused.

[0003] The geomechanical model test of tunnel lining during operation is different from the geomechanical model test of tunnel during construction. It requires prefabricated tunnel lining to reduce unnecessary excavation and support procedures. At present, there is little research on the prefabrication method of tunnel lining. It mainly adopts methods such as artificial formwork filling and steel formwork casting. Artificial formwork filling has a long production cycle, cumbersome process and low repetition rate, and the prefabricated tunnel lining has a large size error, which makes it difficult to achieve a high-precision, short-cycle and high-repetition production device and method; steel formwork casting solves the shortcomings of low lining production precision, low repetition rate and long cycle, but due to the low rigidity of the cast lining material and the high rigidity of the steel mold, the model lining is very likely to crack and damage during disassembly, resulting in the disadvantage of low yield.

[0004] The invention patent with application number 201711352524.7 proposes a tunnel lining prefabrication and embedding device and method in geomechanical model test. The space formed by the spliced ​​outer frame, core plate, bottom plate and bolt connection is the space of tunnel lining. Since the initial strength and rigidity of the lining similar materials are much smaller than that of the steel mold, it is very easy to cause lining cracks, resulting in material waste and low yield rate, and it is not conducive to burying reinforcing steel bars inside the mold to truly simulate the reinforced concrete materials on site, so the scope of application is limited. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the shortcomings of the existing secondary lining model preparation, that is, the model and the mold are one-to-one, the mold cannot be reused, and the model containing reinforcing ribs cannot be prepared, and a large-span tunnel lining model prefabrication device and method in geomechanical model testing is proposed.

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

[0007] A prefabrication device for a large-span tunnel lining model in a geomechanical model test, characterized in that it comprises an inner mold, an outer mold, a bottom plate, a top plate and a plurality of fixed columns, wherein the inner mold and the outer mold are arranged between the bottom plate and the top plate and form a casting cavity for a secondary lining model; the inner mold and the outer mold are both composed of a plurality of flat plates stacked in the vertical direction, and each plate is divided into two halves in the horizontal direction; a plurality of through holes are arranged at corresponding positions on the inner mold, the outer mold, the bottom plate and the top plate, and the fixed columns penetrate the through holes to fix the prefabrication device as a whole; a plurality of discharge ports are arranged on the top plate.

[0008] In the large-span tunnel lining model prefabrication device in the above-mentioned geomechanical model test, a foam buffer layer is provided on the outer side of the inner mold.

[0009] In the large-span tunnel lining model prefabrication device in the above-mentioned geomechanical model test, a plurality of annular reinforcing ribs are arranged in the cavity between the inner mold and the outer mold, a plurality of positioning rods are arranged on the foam buffer layer, and the annular reinforcing ribs are fixed on the positioning rods.

[0010] In the large-span tunnel lining model prefabrication device in the above-mentioned geomechanical model test, the annular reinforcement ribs and the positioning support rods are iron wires welded together.

[0011] In the large-span tunnel lining model prefabrication device in the above-mentioned geomechanical model test, the feed opening is a plurality of arc-shaped through grooves arranged on the upper part of the casting cavity of the secondary lining model.

[0012] In the large-span tunnel lining model prefabrication device in the above-mentioned geomechanical model test, the plate material is a PVC plate, an acrylic plate or a wooden plate.

[0013] A method for prefabricating a tunnel lining model in a geomechanical model test comprises the following steps:

[0014] 【1】Object preparation: According to the requirements of the geomechanical model test, the cross-section of the tunnel secondary lining model is scaled to a certain ratio, and the bottom plate, top plate and plates for splicing the inner and outer molds of corresponding sizes are prepared according to the scaled secondary lining model structure;

[0015] 【2】Inner mold splicing: Insert the fixing column into the through hole at the corresponding position of the inner mold on the bottom plate, and splice the inner mold to the set height;

[0016] 【3】Arrangement of circumferential reinforcement ribs: Wrap a foam buffer layer on the outside of the inner mold and insert one end of the positioning support rod into the foam buffer layer; arrange outer circumferential reinforcement ribs and inner circumferential reinforcement ribs in the casting cavity of the secondary lining model so that the outer circumferential reinforcement ribs and the inner circumferential reinforcement ribs are fixed to the outer exposed end of the positioning support rod;

[0017] 【4】External mold splicing: Splice the external mold to the set height, insert the corresponding fixing column of the external mold, and install the top plate to make the prefabricated device solid as one;

[0018] 【5】Pouring: The lining material with a certain mix ratio is poured into the prefabricated cavity through the feed port and left to stand for a set time;

[0019] 【6】Mold removal: Remove the top plate, inner mold, outer mold and fixed columns layer by layer, remove the foam buffer layer, and obtain the secondary lining model.

[0020] In the large-span tunnel lining model prefabrication method in the above-mentioned geomechanical model test, the static time is 24 hours.

[0021] In the method for prefabrication of the large-span tunnel lining model in the above-mentioned geomechanical model test, the dismantling order in step [6] is to first dismantle the inner mold and then the outer mold; when dismantling the inner mold and the outer mold, first pull out the fixing column and then dismantle the plates of the inner mold and the outer mold in turn.

[0022] The beneficial effects of the present invention are as follows:

[0023] 1. The present invention provides a device and method for prefabricating a large-span tunnel lining model in a geomechanical model test, which overcomes the shortcomings of low precision, low yield, low repetition rate and long cycle of traditional lining production, while reducing the production cost and weight of the prefabricated device. The solution has accurate reinforcement positioning, is easy to disassemble and is inexpensive. It can be used for geomechanical model tests related to various types of tunnel lining cracks and disasters during operation, including mountain tunnels, shield tunnels, submarine tunnels, railway tunnels, hydraulic tunnels, etc. It is closer to engineering tests and has a wider range of uses. It is of great significance for solving the research on tunnel lining cracks and disasters during operation that have high requirements on tunnel lining size.

[0024] 2. The inner and outer molds of the lining model prefabrication device of the present invention are both made of plates spliced ​​into different lengths, which meets the needs of tunnel tests of different lengths in model tests. At the same time, the inner mold, outer mold, top plate and bottom plate of the mold can be reused, reducing the test cost.

[0025] 3. The present invention isolates the inner mold from the cast secondary lining model by arranging a foam buffer layer on the outer circle of the inner mold. On the one hand, it is convenient to take out the inner mold when demolding, thereby ensuring the dimensional and structural integrity of the secondary lining. On the other hand, the foam buffer layer can be used as a support. By inserting a number of positioning support rods, the layout of inner and outer annular reinforcements is realized, thereby realizing the preparation of a secondary lining model containing annular reinforcements and stirrups inside, thereby meeting the accuracy and reliability of the tunnel mechanics model test.

[0026] 4. The inner mold and outer mold of the present invention are made of PVC board, acrylic board or wooden board cut by a laser engraving machine. They are simple to make, light in weight and low in cost. The secondary lining size can be accurately controlled during processing. They have the advantages of simple manufacturing method, reusability and short cycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The secondary lining reinforcement layout diagram for the existing tunnel;

[0028] Figure 2 It is a schematic diagram of the structure of the prefabricated device of the tunnel secondary lining model of the present invention;

[0029] Figure 3 It is a schematic diagram of the cross section of the inner mold and the outer mold of the present invention;

[0030] Figure 4 This is a schematic diagram of the bottom plate structure of the present invention;

[0031] Figure 5 It is a schematic diagram of the top plate structure of the present invention;

[0032] Figure 6 This is a schematic diagram of the installation of the foam buffer layer, reinforcing ribs and positioning support rods of the present invention.

[0033] The accompanying drawings are marked as follows: 1-top plate; 2-fixed column; 3-outer mold; 4-bottom plate; 5-foam buffer layer; 6-inner mold; 7-through hole; 8-outer annular reinforcement rib; 9-inner annular reinforcement rib; 10-positioning support rod; 11-casting cavity; 12-feeding port; 13-hoops. DETAILED DESCRIPTION

[0034] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0035] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0036] like Figure 1 As shown, the traditional tunnel secondary lining includes a concrete structure and internal reinforcements, wherein the reinforcements include outer annular reinforcements 8, inner annular reinforcements 9 and stirrups 13 connected between the outer annular reinforcements 8 and the inner annular reinforcements 9; in the preparation of the secondary lining model, in addition to prefabricating the concrete structure, how to implant the corresponding reinforcements inside the model becomes a difficult problem.

[0037] like Figures 2 to 5 As shown, a prefabricated device for a large-span tunnel lining model in a geomechanical model test of the present invention comprises an inner mold 6, an outer mold 3, a bottom plate 4, a top plate 1 and a plurality of fixed columns 2. The inner mold 6 and the outer mold 3 are arranged between the bottom plate 4 and the top plate 1, and the space between the inner mold 6, the outer mold 3, the bottom plate 4 and the top plate 1 is used to form a casting cavity 11 of the tunnel secondary lining model. The inner mold 6 and the outer mold 3 are both composed of a plurality of flat plates stacked in the vertical direction, and each plate is divided into two symmetrical parts in the horizontal direction by the center line of the tunnel, which is convenient for disassembly and assembly. A plurality of through holes 7 are arranged at corresponding positions on the inner mold 6, the outer mold 3, the bottom plate 4 and the top plate 1, and each through hole 7 corresponds to a fixed column 2. A part of the fixed columns 2 is used to fix the inner mold 6, and another part of the fixed columns 2 is used to fix the outer mold 3. The fixed columns 2 penetrate the through holes 7 to fix the prefabricated device including the inner mold 6, the outer mold 3, the bottom plate 4 and the top plate 1 as a whole to form a spliced ​​frame. The top plate 1 and the bottom plate 4 are spliced ​​at the top and bottom of the spliced ​​frame. The spliced ​​frame can adjust the length of the lining by increasing or decreasing the number of layers of the inner and outer molds according to the length requirement of the test tunnel, thereby meeting the requirements of tunnel model tests of different lengths, and the dismantled components can be reused to avoid waste.

[0038] The above-mentioned plate is a PVC plate, an acrylic plate or a wooden plate, and is processed closely according to the set size by a laser engraving machine to ensure the dimensional accuracy of the model. A plurality of feed openings 12 are arranged on the top plate, and the feed openings 12 are a plurality of arc-shaped through grooves arranged on the upper part of the secondary lining model casting cavity 11, which are used to pour concrete materials similar to the lining for model casting.

[0039] like Figure 6As shown, a foam buffer layer 5 is provided on the outer side of the inner mold 6 to isolate the lining and the inner mold, facilitate the disassembly of the inner mold, and support the reinforcement ribs inside the model. As is known to all, a number of circumferential reinforcement steel bars are provided inside the secondary lining of the tunnel, so in the model test, a secondary lining model with scaled steel bar parameters inside is also required for testing. In practice, how to implant steel bars inside the model has become a difficult problem.

[0040] The present invention adopts an ingenious method. A plurality of outer annular reinforcing ribs 8 and inner annular reinforcing ribs 9 are arranged in the cavity between the inner mold 6 and the outer mold 3. A plurality of positioning rods 10 are arranged on the foam buffer layer 5. The outer annular reinforcing ribs 8 and the inner annular reinforcing ribs 9 are fixed on the positioning rods 10. As a preferred embodiment, the outer annular reinforcing ribs 8, the inner annular reinforcing ribs 9 and the positioning rods 10 are welded iron wires. When implemented, one end of a plurality of positioning iron wires is first inserted into the foam buffer layer 5 at a set height, and then the annular iron wire is welded to the positioning iron wire for fixing. The depth of the annular iron wire in the model can also be adjusted by positioning iron wires of different lengths. In this way, several circles of outer annular reinforcement ribs 8 and inner annular reinforcement ribs 9 are laid out. During pouring, concrete material is injected into the pouring cavity 11 through the discharge port 12, and the annular iron wire and the positioning iron wire are poured inside the model. The diameter and density of the iron wire and the pouring material need to be selected according to the requirements of the simulation test to ensure the accuracy and representativeness of the scaled test.

[0041] The present invention realizes the preparation of a tunnel secondary lining model with a length of 30cm to 100cm, a height of 36cm and a width of 54cm, wherein the thickness of the plate is 1.5cm, the thickness of the foam buffer layer is 1cm, and the diameter of the iron wire is 0.7mm to 1.2mm. The foam buffer layer can be made of high-density rubber and plastic sponge, which is arranged close to the inner side of the mold during installation, and at the same time reduces the stress concentration on the lining structure when the mold is demolded.

[0042] The method for preparing a tunnel secondary lining model using the above device comprises the following steps:

[0043] 【1】Object preparation: According to the requirements of the geomechanical model test, the cross-section of the tunnel secondary lining model is scaled according to a certain ratio, and the size of the lining is determined according to the principle of similarity ratio. According to the scaled secondary lining model structure, the bottom plate 4, top plate 1 and the spliced ​​inner mold 6 and outer mold 3 plates of corresponding sizes are prepared; the PVC board, acrylic board or wooden board is cut into plates of appropriate sizes using a laser engraving machine. The bottom plate only needs to have fixed column holes, the inner mold and the outer mold need to have holes and the lining contour needs to be cut and formed. In addition to the fixed column holes, the top plate also needs to have larger holes for pouring similar materials to the lining.

[0044] [2] Inner mold splicing: Place the base plate 4 at the bottom of the device, insert the fixing column 2 into the through hole at the corresponding position of the inner mold 6 on the base plate 4, and splice the inner mold 6 to the set height; you can also place the base plate at the bottom, assemble the inner mold to a certain height, and fix the position with a fixing column.

[0045] [3] Arrangement of the annular reinforcement ribs: Wrap the foam buffer layer 5 on the outer side of the inner mold 6, and insert one end of the positioning support rod 10 into the foam buffer layer 5; arrange the outer annular reinforcement ribs 8 and the inner annular reinforcement ribs 9 in the casting cavity 11 of the secondary lining model, so that the annular reinforcement ribs are fixed to the exposed end of the positioning support rod 10; specifically, the outer annular reinforcement ribs 8, the inner annular reinforcement ribs 9 and the positioning support rod 10 are all made of iron wire, and one end of the positioning iron wire is inserted into the foam buffer layer 5 according to a set height, and then the annular iron wire is welded to the exposed end of the positioning iron wire;

[0046] 【4】External mold splicing: Splice the external mold 3 to the set height, insert the fixing column 2 corresponding to the external mold 3, and install the top plate 1, so that the prefabricated device is fixed as one;

[0047] 【5】Casting: Cast a lining material with a certain mix ratio into the prefabricated cavity through the discharge port 12 and leave it to stand for a set time; according to the test requirements and the mix ratio of similar materials, cast the evenly mixed similar materials into the mold, which generally needs to be left to stand for 24 hours.

[0048] 【6】Mold removal: Remove the top plate 1, inner mold 6, outer mold 3 and fixed column 2 layer by layer, remove the foam buffer layer 5, and obtain the secondary lining model. After removing the excess lining-like materials on the upper part of the inner and outer molds, remove the inner mold and foam buffer layer, and remove the outer mold after the lining reaches a certain strength. The order of removal is to remove the inner mold first, then the outer mold; when removing the inner mold and the outer mold, first pull out the fixed column and then remove the plates of the inner mold and the outer mold in turn.

[0049] When the prepared secondary lining model is subjected to geomechanical model test, similar materials to the surrounding rock are buried to a certain height, the prefabricated tunnel lining is buried, and the surrounding rock materials are buried to a certain height. Subsequent work such as load application and deformation and stress monitoring are carried out according to the test requirements.

[0050] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for prefabricating a large-span tunnel lining model in a geomechanical model test, characterized in that: The following steps are involved: [1] Object preparation: According to the requirements of the geomechanical model test, the cross section of the tunnel secondary lining model is scaled according to a certain ratio, and the bottom plate (4), top plate (1) and the plates for splicing the inner mold (6) and the outer mold (3) of corresponding sizes are prepared according to the scaled secondary lining model structure; [2] Inner mold splicing: insert the fixing column (2) into the through hole at the corresponding position of the inner mold (6) on the bottom plate (4), and splice the inner mold (6) to a set height; [3] Arrangement of annular reinforcement ribs: Wrap a foam buffer layer (5) on the outer side of the inner mold (6), and insert one end of a positioning support rod (10) into the foam buffer layer (5); arrange outer annular reinforcement ribs (8) and inner annular reinforcement ribs (9) in the casting cavity (11) of the secondary lining model, so that the outer annular reinforcement ribs (8) and the inner annular reinforcement ribs (9) are fixed to the outer exposed end of the positioning support rod (10); [4] External mold splicing: Splice the external mold (3) to a set height, insert the fixing column (2) corresponding to the external mold (3), and install the top plate (1) so that the prefabricated device is fixed as a whole; 【5】Pouring: pouring lining materials of a certain mix ratio into the prefabricated cavity through the discharge port (12) and leaving them to stand for a set time; [6] Dismantling the mold: dismantling the top plate (1), inner mold (6), outer mold (3) and fixed column (2) layer by layer, removing the foam buffer layer (5), and obtaining the secondary lining model; The secondary lining model prefabrication device comprises an inner mold (6), an outer mold (3), a bottom plate (4), a top plate (1) and a plurality of fixed columns (2); the inner mold (6) and the outer mold (3) are arranged between the bottom plate (4) and the top plate (1) to form a casting cavity (11) for the secondary lining model; the inner mold (6) and the outer mold (3) are both composed of a plurality of flat plates stacked in the vertical direction, and each plate is divided into two halves in the horizontal direction; a plurality of through holes (7) are arranged at corresponding positions on the inner mold (6), the outer mold (3), the bottom plate (4) and the top plate (1), and the fixed columns (2) penetrate the through holes (7) to fix the prefabrication device as a whole; and a plurality of discharge ports (12) are arranged on the top plate.

2. The method for prefabricating a large-span tunnel lining model in a geomechanical model test according to claim 1, characterized in that: The standing time in step [5] is 24 hours.

3. The method for prefabricating a large-span tunnel lining model in a geomechanical model test according to claim 1, characterized in that: In step [6], the dismantling order is to first remove the inner mold and then remove the outer mold; when removing the inner mold and the outer mold, first pull out the fixing column and then remove the plates of the inner mold and the outer mold in turn.

4. The method for prefabricating a large-span tunnel lining model in a geomechanical model test according to claim 1, characterized in that: A foam buffer layer (5) is arranged on the outer side of the inner mold (6).

5. The method for prefabricating a large-span tunnel lining model in a geomechanical model test according to claim 4, characterized in that: A plurality of outer annular reinforcing ribs (8) and inner annular reinforcing ribs (9) are arranged in the cavity between the inner mold (6) and the outer mold (3); a plurality of positioning support rods (10) are arranged on the foam buffer layer (5); and the outer annular reinforcing ribs (8) and inner annular reinforcing ribs (9) are fixed on the positioning support rods (10).

6. The method for prefabricating a large-span tunnel lining model in a geomechanical model test according to claim 5, characterized in that: The outer annular reinforcing rib (8), the inner annular reinforcing rib (9) and the positioning support rod (10) are iron wires welded together.

7. The method for prefabricating a large-span tunnel lining model in a geomechanical model test according to claim 1, characterized in that: The material discharge opening is a plurality of arc-shaped through grooves arranged on the upper part of the secondary lining model casting cavity (11).

8. The method for prefabricating a large-span tunnel lining model in a geomechanical model test according to claim 1, characterized in that: The board material is PVC board, acrylic board or wooden board.

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