Expansion Force Relief Device and Relief Method for Expanding Rock Railway Tunnels

Abstract

This invention provides a pressure-relieving device and method for expanding rock railway tunnels, belonging to the technical field of tunnel construction auxiliary equipment. The device includes a rod body formed by rolling a single steel sheet into three layers of rolled steel sheets. Multiple steel plates are evenly connected between the innermost rolled steel sheets, and each steel plate passes through the center of a ring formed by the rolled steel sheet. Appropriate gaps are reserved between each layer of rolled steel sheets. One end of one of the steel plates is connected to the end of the steel sheet. This invention can release the expansion force of expanding rock tunnels, thereby reducing the probability of tunnel floor arching. It can also increase the strength, stiffness, and structural suitability and compatibility of the surrounding rock and support, thus extending the service life of the project and reducing subsequent project operation and maintenance costs.

Description

Technical Field

[0001] This invention relates to the field of tunnel construction auxiliary equipment technology, specifically to an expansion force relief device and method for expansion rock railway tunnels. Background Technology

[0002] For newly built high-speed railway tunnels, ballastless track technology is generally adopted. Before laying the track slabs, the construction quality of the tunnel bottom must be assessed, and the standards are high. During operation, if defects such as arching deformation occur at the tunnel bottom, it will pose a significant risk to train safety. Generally, arching deformation of the tunnel bottom structure is mainly due to plastic shear expansion. When the bottom is composed of expansive soil minerals, the water content will increase significantly, causing the bottom to expand and deform, resulting in arching defects in the bottom structure.

[0003] From the perspective of destructive mechanics characteristics, tunnel floor arching can generally be classified into four types: compression-flow type, water-swellable type, shear-displacement type, and flexural-fold type. Among these, water-swellable type refers to the phenomenon where severely expanding ores with high hydrophilic components expand and soften upon contact with water, rapidly increasing in volume and causing significant deformation of the surrounding rock. The expanding rock at the tunnel floor is subjected to triaxial compression; the greater the expansion rate, the greater the ultimate expansion pressure. Once the ultimate expansion pressure exceeds the structural resistance of the tunnel floor, tunnel floor arching occurs. Furthermore, expanding rock poses significant engineering risks, partly due to complex changes caused by engineering disturbances, and partly because the deformation patterns and constitutive relationships of expanding rock under external forces are not yet fully understood. Summary of the Invention

[0004] The purpose of this invention is to provide an expansion force relief device and method for expanding rock railway tunnels, which can be applied to railway tunnels, highway tunnels, coal mine roadways, etc., and can effectively reduce the arching of the tunnel floor and improve the overall structural stability and safety, so as to solve at least one of the technical problems existing in the above-mentioned background art.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] On one hand, the present invention provides a pressure relief device for the expansion force of an expansion rock railway tunnel, comprising:

[0007] The pressure device rod is made of a steel sheet rolled into three layers of rolled steel sheets. Multiple steel plates are evenly connected between the innermost layers of rolled steel sheets. All of the steel plates pass through the center of the ring formed by the rolled steel sheet. Appropriate gaps are reserved between each layer of rolled steel sheets.

[0008] One end of the steel plate is connected to the end of the steel sheet.

[0009] On the other hand, the present invention provides a method for relieving the expansion force of an expansion rock railway tunnel based on the expansion force relief device described above, comprising:

[0010] Measure the upper and lower lines of the reserved steel bars, and calculate the transverse excavation depth of the pre-excavated invert section based on the height difference between the baseline elevation and the invert excavation surface elevation, so as to ensure that the invert excavation depth meets the design requirements.

[0011] Excavation of the arch wall and inverted arch;

[0012] Drilling and placement;

[0013] Initial support and secondary lining of the invert arch;

[0014] Backfilling and pouring of the inverted arch.

[0015] Preferably, the excavation of the arch wall and the invert includes: the excavation of the invert soil layer is carried out by manual and mechanical excavation. Depending on the type of surrounding rock, when using upper and lower steps for excavation, the length of the excavation section is controlled. For Class V surrounding rock sections, the excavation length should be ≤3m, for Class IV surrounding rock sections, the excavation length should be ≤5m, and for Class III and above surrounding rock sections, the excavation length should be ≤10m.

[0016] Preferably, when the surrounding rock conditions are good, the maximum depth should not exceed 15m. The connection between the two corners of the tunnel bottom and the sidewall should be excavated smoothly to avoid stress concentration. The debris at the bottom of the sidewall steel frame should be cleaned to ensure good connection with the inverted arch steel frame. When encountering expansive surrounding rock with large deformation, pressure relief devices should be pre-installed at the two corners of the bottom before excavation.

[0017] Preferably, after the prefabricated pressure relief device is transported to the site, the anchor drilling machine is used to drill holes in sequence. After drilling, it is necessary to ensure that there are no residues or debris in the holes before placing the device into the drilled holes. Then, concrete is poured to the design elevation of the bottom of the invert arch. The concrete grade must be the same as the leveling layer concrete grade and be constructed simultaneously with the leveling layer.

[0018] Preferably, the initial support and secondary lining of the invert arch include: before constructing each support structure, measuring the geometric dimensions of the base elevation and checking whether it meets the design requirements, cleaning up loose burrs, debris and water accumulation in the foundation pit, and then laying a concrete leveling layer; then installing the invert arch steel frame, and then carrying out the initial support construction of the invert arch, installing the arch foot drainage pipe, binding the secondary lining reinforcement, erecting the formwork, and pouring the invert arch concrete.

[0019] Preferably, the installation of the invert arch steel support must meet the design and specification requirements and be firmly welded to the side wall arch frame; the extension length of the pre-embedded steel bars in the side wall of the secondary lining on both sides of the invert arch should meet the requirements for welding with the circumferential secondary lining steel bars, and the joints should be staggered so that the number of steel bar joints in the same section does not exceed 50% of the total number. The binding of the secondary lining steel bars of the invert arch must ensure the spacing, and the layer spacing is ensured by welding positioning steel bars.

[0020] Preferably, the backfilling and pouring of the invert arch includes: using a top formwork with pre-reserved vibration holes to ensure that the concrete is vibrated and compacted; the invert arch concrete can be poured by pumping concrete; the location of the reserved settlement joint should be designed in advance before the construction of the invert arch; the settlement joint should ensure that the secondary lining concrete, the arch wall, and the invert arch are disconnected on the same vertical plane, and the settlement joint should be treated as required.

[0021] The beneficial effects of this invention are: it can release the expansion force of the expansive rock tunnel, thereby reducing the probability of tunnel bottom arching; it can also increase the strength and rigidity of the surrounding rock and support, as well as the structural applicability and compatibility between the two, thereby extending the service life of the project and reducing the later operation and maintenance costs.

[0022] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and will become apparent from the description or may be learned by practice of the invention. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the water-swellable tunnel bottom arch as described in an embodiment of the present invention.

[0025] Figure 2 This is a schematic diagram of the expansion force relief device applied to the cross section of a single-track tunnel of a high-speed railway according to an embodiment of the present invention.

[0026] Figure 3 This is a schematic diagram of the expansion force relief device applied to the longitudinal section of a single-track tunnel of a high-speed railway according to an embodiment of the present invention.

[0027] Figure 4 This is a schematic diagram of the factory prefabrication of the expansion force relief device according to an embodiment of the present invention.

[0028] Wherein: 1-steel sheet; 2-steel plate; 3-gap. Detailed Implementation

[0029] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0030] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0031] It should also be understood that terms such as those defined in general dictionaries should be understood to have meanings consistent with their meanings in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless defined as described here.

[0032] Those skilled in the art will understand that, unless specifically stated otherwise, the singular forms “a,” “an,” “the,” and “the” used herein may also include the plural forms. It should be further understood that the term “comprising” as used in this specification means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, and / or groups thereof.

[0033] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of those different embodiments or examples.

[0034] In the description of this specification, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0035] In the description of this specification, the terms “center,” “upper,” “lower,” “front,” “rear,” “left,” “right,” “vertical,” “horizontal,” “top,” “bottom,” “inner,” and “outer,” etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this technology and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this technology.

[0036] Unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "setting" should be interpreted broadly. For example, they can refer to a fixed connection or setting, a detachable connection or setting, or an integral connection or setting. Those skilled in the art can understand the specific meaning of these terms in this art according to the specific circumstances.

[0037] To facilitate understanding of the present invention, the present invention will be further explained and described below with reference to the accompanying drawings and specific embodiments. However, the specific embodiments do not constitute a limitation on the embodiments of the present invention.

[0038] Those skilled in the art should understand that the accompanying drawings are merely schematic diagrams of embodiments, and the components in the drawings are not necessarily essential for implementing the present invention.

[0039] Example

[0040] like Figures 1 to 4 As shown in this embodiment, an expansion force relief device and method for an expansion rock railway tunnel are provided. Taking a single-track high-speed railway tunnel as an example, the tunnel invert is subjected to the vertical load transmitted from the upper strata and the self-weight of the structure through the arch foot. The bottom is subjected to the upward reaction force of the lower foundation and the expansion force. Under the interaction of these multiple forces, the invert and its filling interior form a large internal force. In addition, the long-term operation of the train causes the tunnel structure to generate large structural internal forces in both the transverse and longitudinal directions.

[0041] The pressure relief device rod is made of three layers of rolled steel sheets 1 (thickness d) stacked together. The inner layers of rolled steel sheets are connected by three sets of through-center, continuous steel plates 2, and appropriate gaps 3 are reserved between each layer of rolled steel sheets.

[0042] As drilling progresses in front of the pressure-yielding device, the reaction force and expansion force of the strata at the tunnel floor are released to some extent, the triaxial stress is transformed into biaxial stress, and the vertical force is reduced to a certain degree. To compensate for and resist these internal forces, the pressure-yielding device, during pressure yielding, compresses the steel sheets of the rod as the surrounding rock expands, causing the steel sheets to gradually contract and slide until they are completely overlapped. The radial contraction of the rod during pressure yielding increases the tensile strength of the pressure-yielding device. The pressure yielding force is generally less than the yield load of the steel sheet, ensuring that the rod material is in the elastic deformation stage during the pressure yielding process. After pressure yielding, it can more effectively participate in the support system through its anchoring force, tensile force, and overall stability of the anchor body, reducing the tunnel floor camber.

[0043] The steps of this invention will be explained below:

[0044] 1. Factory-prefabricated expansion force relief device

[0045] The expansion force relief device (hereinafter referred to as the device) consists of: a steel sheet rolled into 3 layers of stacked steel coils and an inner continuous steel plate 2, wherein: the 3 layers of stacked steel coils have a diameter of 200-220mm, the inner continuous steel plate is 3000mm long and 200mm wide, the circumferential spacing of the relief device is 1.2m, the longitudinal spacing is 1.5m, and the relief device is arranged in a quincunx pattern along the longitudinal direction of the tunnel.

[0046] 2. Measurement and layout

[0047] The upper and lower lines of the reserved steel bars need to be accurately measured. Based on the height difference between the baseline elevation and the excavation surface elevation of the invert arch, the excavation depth at every 1m interval in the transverse direction of the pre-excavated invert arch section should be calculated to ensure that the excavation depth of the invert arch meets the design requirements.

[0048] 3. Excavation of arch walls and inverts

[0049] Excavation of the invert arch soil layer should primarily rely on a combination of manual and mechanical methods. Depending on the surrounding rock type, when using stepped excavation, the length of the excavation section must be controlled. Generally, for Class V surrounding rock, the excavation length should be ≤3m; for Class IV surrounding rock, ≤5m; and for Class III and above surrounding rock, ≤10m. When the surrounding rock conditions are relatively good, the maximum length should not exceed 15m. The connection between the tunnel bottom corners and the sidewalls should be excavated smoothly to avoid stress concentration. Debris at the bottom of the sidewall steel frame should be cleaned to ensure a good connection with the invert arch steel frame. If encountering expansive surrounding rock with significant deformation, pressure relief devices should be pre-installed at the bottom corners, or other reinforcement measures should be taken before excavation.

[0050] 4. Drilling and Placement

[0051] After the prefabricated device is transported to the site, holes are drilled sequentially using an anchor drilling rig. After drilling, it is necessary to ensure that there are no residues or debris in the holes before placing the device into the drilled holes. Then, concrete is poured up to the design elevation at the bottom of the invert arch. The concrete grade must be the same as that of the leveling layer concrete, and the construction is carried out simultaneously with the leveling layer.

[0052] 5. Initial support and secondary lining of the invert arch

[0053] Before constructing any support structure, the elevation and geometric dimensions of the foundation bottom must be measured to ensure they meet design requirements. Loose framing, debris, and accumulated water in the foundation pit must be thoroughly cleaned before laying a concrete leveling layer. Next, the invert arch steel frame is installed, followed by the initial invert arch support construction, installation of arch foot drainage pipes, binding of secondary lining reinforcement, formwork erection, and pouring of the invert arch concrete. The installation of the invert arch steel supports must meet design and specification requirements and be securely welded to the sidewall arch frames. The extension length of the pre-embedded reinforcement bars on both sides of the secondary lining sidewalls of the invert arch should meet the requirements for welding with the circumferential secondary lining reinforcement bars, and the joints should be staggered so that the number of reinforcement joints in the same section does not exceed 50% of the total. The binding of the invert arch secondary lining reinforcement bars must maintain proper spacing, and the layer spacing is ensured by welding positioning reinforcement bars.

[0054] 6. Backfilling and pouring of the invert arch

[0055] Before pouring the invert arch, the concrete mix ratio should be strictly demonstrated. Top formwork with pre-reserved vibration holes should be used to ensure the concrete is compacted. Pumped concrete can be used for pouring the invert arch concrete. Before constructing the invert arch, the location of the reserved settlement joint should be designed in advance. The settlement joint should ensure that the secondary lining concrete, arch wall and invert arch are disconnected on the same vertical plane. The settlement joint should be treated as required to ensure the construction quality. In areas where the surrounding rock does not change much, expansion joints should be set as few as possible or not at all to ensure that the lining does not have drainage problems.

[0056] In summary, the expansion force relief device for railway tunnels in expansive rock of this invention is rationally designed based on the actual conditions of the surrounding rock and support. It first releases and relieves the expansion force, and then anchors the tunnel floor on this basis. The combination of these two methods can greatly increase the stability of the tunnel floor structure and suppress tunnel floor heave. At the same time, this method is simple to operate and has low cost, and can be widely used in the prevention and control of tunnel floor arching defects in railway tunnels, highway tunnels, coal mine roadways, and other tunnels.

[0057] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that, based on the technical solutions disclosed in the present invention, various modifications or variations that can be made by those skilled in the art without creative effort should be included within the scope of protection of the present invention.

Claims

1. An expansion rock railway tunnel expansion force yielding device-based method for yielding to the expansion force of an expansion rock railway tunnel, characterized by, The expansion rock railway tunnel expansion force yielding device comprises a yielding device rod body formed by three layers of coiled steel sheets, wherein the innermost coiled steel sheets are uniformly connected with a plurality of steel plates, the plurality of steel plates are all through the center of the ring formed by coiling the steel sheets, and appropriate gaps are reserved between each layer of coiled steel sheets; one end of the steel plate is connected with the end of the steel sheet; the method comprises the following steps: measuring the upper and lower lines of the reserved steel bars, calculating the transverse excavation depth of the pre-excavation inverted arch section according to the height difference between the baseline elevation and the inverted arch excavation surface elevation, so as to ensure that the inverted arch excavation depth meets the design requirements; arch wall and inverted arch excavation; drilling and placing; inverted arch primary support and secondary lining; inverted arch backfilling and pouring; The arch wall and inverted arch excavation comprises the following steps: excavating the inverted arch soil layer by artificial and mechanical excavation, controlling the length of the excavation section according to the different types of surrounding rocks, the excavation length should be ≤3m for V-class surrounding rock sections, the excavation length should be ≤5m for IV-class surrounding rock sections, and the excavation length should be ≤10m for III-class and above surrounding rock sections; When the surrounding rock condition is good, the maximum should not exceed 15m, the tunnel bottom corners and the side wall connection should be smoothly excavated to avoid causing stress concentration, the bottom of the side wall steel frame should be clean to ensure good connection with the inverted arch steel frame; when the deformation of the expansion surrounding rock is large, the bottom corners should be pre-drilled with a yielding device before excavation; After the factory-prepared yielding device is transported to the site, the anchor rod drill is used to drill holes in sequence; after drilling, it is necessary to ensure that there is no residue and sundries in the hole, then the device is placed in the hole, and then concrete is poured to the design elevation of the inverted arch bottom, and the concrete grade should be the same as that of the leveling layer and should be constructed simultaneously with the leveling layer; The inverted arch primary support and secondary lining comprise the following steps: before the installation of each support structure, the base bottom elevation geometric size is measured, whether it meets the design requirements is checked, the virtual drilling, sundries and accumulated water in the foundation pit are cleaned, and then the concrete leveling layer is laid; then the inverted arch steel frame is installed, the inverted arch primary support construction is carried out, the inverted arch concrete is poured.

2. The method of claim 1, wherein, The installation of the inverted arch steel support must meet the design and specification requirements, and the welding between the inverted arch and the side wall arch frame must be firm; the pre-embedded steel reinforcement on both sides of the inverted arch two lining side wall part should meet the requirements of welding with the ring two lining steel reinforcement, and the joints should be staggered, so that the number of steel joints in the same section is not more than fifty percent of the total number, and the binding of the inverted arch two lining steel reinforcement must ensure the spacing, and the layer spacing is ensured by welding positioning steel reinforcement.

3. The method of claim 1, wherein, The inverted arch backfilling and pouring comprise the following steps: the top mold construction is used to ensure the compaction of the concrete, and the inverted arch concrete is poured by pumping concrete; the position of the reserved settlement joint should be designed in advance before the inverted arch construction, the settlement joint should ensure that the two lining concrete, arch wall and inverted arch are disconnected in the same vertical plane, and the settlement joint should be treated according to the requirements.

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