Self-propelled grouting anchor rod advance support process for tunnel penetrating through corrosion rock stratum

Abstract

The invention relates to a self-propelled grouting anchor rod advance support process for a tunnel penetrating through a corrosion rock stratum, which comprises the following steps of: taking surrounding rock in front of a tunnel face as a main bearing body, and forming a combined arch structure above the tunnel face through a plurality of self-propelled grouting anchor rods which are arranged in a sector ring at a certain angle and a certain interval; a transverse stress ring area along an excavation contour line is formed, unbalanced stratum stress above a tunnel face extends to the deep position of a rock mass, an arch structure with surrounding rock as a bearing body is formed, and the surrounding rock, an anchor rod body and permeation grouting form a forepoling system. The self-propelled grouting anchor rods are adopted to pre-reinforce the surrounding rock in front of the tunnel face in advance, and the stability of the surrounding rock in the construction process is improved; according to the supporting technology, the complex working procedure that a pipe shed working chamber needs to be constructed in a tunnel body in conventional advanced pipe shed supporting is avoided, and the technical problem that under the condition of corrosion limestone stratum surrounding rock joint fissure development, drill jamming is prone to occurring in pipe shed drilling operation construction or the success rate of secondary insertion of a pipe shed steel pipe into a hole is low is solved.

Description

Technical Field

[0001] The invention relates to the technical field of tunnel engineering constructed by mining method, and in particular to a self-advanced grouting anchor advance support technology for a tunnel passing through a karst rock layer. Background Art

[0002] With the large-scale development and utilization of urban underground space and the improvement of urban road network systems, the construction of large-span and extra-large-span tunnels has also increased. When tunnels pass through soluble rock formations, they are generally mainly soluble carbonate rock formations (limestone, limestone, and mudstone). Such formations usually have uneven weathering zones of limestone due to the long-term dissolution of groundwater. The karst forms are mostly steeply inclined karst gullies, caves, funnels, or dissolution fissures. The karst gullies and caves are extremely irregular in shape, and the karst rock surface is relatively complex. When a dark-cut tunnel passes through the above-mentioned dissolution formations, it is common for karst fillings above the face to collapse, loose and broken rocks or large boulders to fall, and even tunnel collapses to the surface. In order to ensure the stability of the surrounding rock of the tunnel face, long-distance advance pre-reinforcement measures should be taken. Conventional advance pipe-roof support requires the construction of a pipe-roof studio in the tunnel body. The studio needs to expand the tunnel section in advance, and the operation process is complicated. At the same time, the pipe-roof construction requires drilling holes first and then inserting perforated steel pipes into the holes. This type of dissolved limestone formation has developed joints and fissures in the surrounding rock, and isolated rocks frequently appear in the dissolved cavity. The drilling operation of the pipe-roof is prone to drill jams, or the success rate of the second insertion of the pipe-roof steel pipe into the hole is low. A self-propelled grouting anchor advance support technology for tunnels that pass through dissolved rock formations is urgently needed to ensure safe tunnel construction. Summary of the invention

[0003] According to the technical problems raised above, a self-advanced grouting anchor advance support technology for tunnels passing through soluble rock layers is provided. Compared with the traditional large pipe-roof construction method for tunnels, the self-advanced grouting anchor advance support technology can be more convenient and quick to construct in the tunnel body section, ensuring the continuous pre-reinforcement of the surrounding rock of the tunnel arch, and overcoming the problem of low success rate of drill sticking or secondary insertion during conventional large pipe-roof drilling.

[0004] The technical means adopted by the present invention are as follows:

[0005] A self-advanced grouting anchor advance support technology for a tunnel that passes through a karst rock formation, which takes the surrounding rock in front of the tunnel face as the main bearing body, forms a combined arch structure above the tunnel face through a number of self-advanced grouting anchors arranged in a fan ring at a certain angle and a certain spacing, forms a lateral stress ring area along the excavation contour line, extends the unbalanced stratum stress above the tunnel face to the depth of the rock mass, forms an arch structure with the surrounding rock itself as the bearing body, and forms an advance support system with the surrounding rock, anchor body, and penetration grouting.

[0006] Furthermore, the self-propelled grouting anchor drilling equipment adopts a three-arm drilling rig to realize mechanized operations of drilling, pipe connection, and multiple pipes at the same time.

[0007] Furthermore, the self-propelled grouting anchor comprises a hollow anchor rod body, a connecting sleeve, a drill bit, an arched pad, a nut and a grouting plug. The output end of the hollow anchor rod body is provided with a drill bit, which is also a hollow structure. The connecting sleeve is arranged between two sections of the hollow anchor rod body. The hollow anchor rod body close to the input end is provided with a grouting plug. The end of the hollow anchor rod body close to the input end is provided with the arched pad, and the other side of the arched pad is provided with a nut. Based on the self-propelled grouting anchor, drilling, grouting and anchoring are realized. Convenient one-time construction support.

[0008] Furthermore, the self-advanced grouting anchor rods are evenly arranged within 120° of the tunnel arch with the tunnel center as the central axis. The angle between the self-advanced grouting anchor rods and the longitudinal axis of the tunnel is 12° to 25°, forming an arch structure with a thickness of 1.5m to 3.5m on the excavation contour line within 120° of the tunnel arch.

[0009] Furthermore, after the self-propelled grouting anchor reaches the specified depth, grouting operation is performed at the tail end. When groundwater develops in the erosion stratum in front of the face, water glass can be added to the injected cement slurry to achieve rapid setting.

[0010] Furthermore, before grouting, grouting tests and anchor and anchor body pull-out tests are carried out, and the cement slurry ratio is adjusted to achieve the best anchoring effect of the anchor body. When pore water is developed in the dissolution zone, water glass material is added to the cement slurry to form cement-water glass slurry. The water glass modulus m used for grouting is between 2.4 and 2.8, and the water glass concentration is 30° to 40° Be'. The gelling time is 20 sec to 1 min by adjusting the grouting material ratio.

[0011] Furthermore, the longitudinal overlap length of the self-advanced anchor rod is not less than 2.0m.

[0012] Compared with the prior art, the present invention has the following advantages: the present invention uses self-propelled grouting anchor rods to pre-reinforce the surrounding rock in front of the tunnel face, thereby improving the stability of the surrounding rock during construction; this support technology avoids the complex process of constructing a pipe-roof studio in the tunnel body required for conventional advance pipe-roof support, and avoids the technical problems of drill jamming or low success rate of secondary insertion of pipe-roof steel pipes in the case of developed joints and fissures in the surrounding rock of such soluble limestone strata. The construction process of the present invention mostly adopts mechanized operations, with a high degree of mechanization and high construction efficiency. Operators can stay away from the face, and the construction safety is higher. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0014] Figure 1 It is a schematic diagram of the combined arch structure formed by the self-advancing anchor rod of the present invention.

[0015] Figure 2 It is a schematic diagram of the longitudinal arrangement of the self-advancing anchor rod of the present invention.

[0016] Figure 3 It is a schematic diagram of the self-advanced grouting anchor rod of the present invention.

[0017] Figure 4 It is a schematic diagram of the three-arm rock drilling trolley of the anchor construction equipment of the present invention. DETAILED DESCRIPTION

[0018] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0019] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. 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 "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0021] Unless otherwise specifically stated, the relative arrangement of the parts and steps described in these embodiments, the numerical expressions and numerical values ​​do not limit the scope of the present invention. At the same time, it should be clear that, for ease of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship. The technology, methods and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be regarded as part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0022] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention: the directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0023] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below their position devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0024] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0025] In the industry standard "Highway Tunnel Design Specifications Volume 1 Civil Engineering" JTG 3370.1-2018, 13.2.3 advance anchors can be used in soft strata without groundwater, thin horizontal layered rock strata, and areas where the arch surrounding rock may peel off or partially collapse within a few hours of excavation. However, in the prior art, there are no advance pre-reinforcement measures for surrounding rock in case of dark-cut tunnels passing through the unevenly weathered limestone zone under the action of groundwater dissolution. The present invention mainly ensures the stability of the surrounding rock of the tunnel face through the advance pre-reinforcement effect of the self-propelled grouting anchor, which belongs to the field of tunnel engineering technology of mining method construction.

[0026] Specifically, Figures 1 to 4 As shown, the embodiment of the present invention discloses a self-advanced grouting anchor advance support process for a tunnel that passes through a karst rock formation. The surrounding rock in front of the tunnel face is used as the main bearing body. A plurality of self-advanced grouting anchors arranged in a fan ring at a certain angle and a certain spacing are used to form a combined arch structure above the face, thereby increasing the cohesion c and internal friction angle φ of the surrounding rock anchoring zone, eliminating the shear damage state of the surrounding rock, forming a transverse force ring zone along the excavation contour line, extending the unbalanced stratum stress above the face to the depth of the rock mass, forming an arch structure with the surrounding rock itself as the bearing body, and forming an advance support system with the surrounding rock, anchor body, and infiltration grouting. Among them, the anchor can suspend large boulders, connect the boulders to the surrounding surrounding rocks through one or more local anchors, and achieve the suspension effect on local boulders and unstable blocks through the high tensile strength of the anchor body, thereby preventing the collapse of unstable blocks on the top of the face.

[0027] The support technology mechanism of the present invention takes the basic principle of the New Austrian Tunneling Method as the theoretical starting point, and adopts the existing engineering construction technology to give full play to the rock mass as the main bearing unit of the tunnel. The present invention can realize the advance pre-reinforcement function of the self-propelled grouting anchor rod, and at the same time, such anchor rods can provide sufficient bearing stiffness, and realize the advance pre-reinforcement of the surrounding rock of the face by utilizing the stiffness of the anchor rod body and the grouting function, thereby ensuring the safe construction of the tunnel.

[0028] The self-propelled grouting anchor drilling equipment adopts a three-arm rock drilling rig to realize mechanized operations of drilling, pipe connection, and multi-pipe connection at the same time.

[0029] The self-propelled grouting anchor includes a hollow anchor rod body, a connecting sleeve, a drill bit, an arch pad, a nut and a grouting plug. The output end of the hollow anchor rod body is provided with a drill bit, which is also a hollow structure. The connecting sleeve is arranged between two sections of the hollow anchor rod body. The hollow anchor rod body near the input end is provided with a grouting plug. The end of the hollow anchor rod body near the input end is provided with the arch pad. The other side of the arch pad is provided with a nut. Based on the self-propelled grouting anchor, drilling, grouting and anchoring are realized in one-time and convenient construction support. After the steel pipe is drilled to a specified depth, grouting can be carried out at the tail end. Grouting is mainly achieved through the grouting holes on the hollow rod body and the drill bit at the front end of the rod body. In this embodiment, the self-propelled grouting anchor rod body adopts a threaded steel pipe with an outer diameter of 32mm, 52mm, and 72mm. The rod diameter and annular spacing arrangement should be selected according to the excavation span of the single tunnel.

[0030] The single-cycle support length of the self-advanced grouting anchor is usually based on a module of 3m. The self-advanced grouting anchor is evenly arranged within 120° of the tunnel arch with the center of the tunnel as the central axis. The angle between the self-advanced grouting anchor and the longitudinal axis of the tunnel is 12° to 25°, forming an arch structure with a thickness of 1.5m to 3.5m on the excavation contour line within 120° of the tunnel arch.

[0031] As an optional implementation, during the drilling process of the self-propelled grouting anchor rod, in order to prevent deformation or collapse of the surrounding rock, the sprayed concrete used along the periphery of the tunnel body forms a sprayed concrete structure, and the self-propelled grouting anchor rod moves along the sprayed concrete structure.

[0032] The self-propelled grouting anchor rod performs grouting operation at the tail end after reaching the specified depth. When groundwater develops in the erosion stratum in front of the face, water glass can be added to the injected cement slurry to achieve rapid setting.

[0033] Before grouting, grouting tests and anchor and anchor body pull-out tests are carried out, and the cement slurry ratio is adjusted to achieve the best anchoring effect for the anchor body. When pore water is developed in the dissolution zone, water glass material is added to the cement slurry to form cement-water glass slurry. The water glass modulus m for grouting is between 2.4 and 2.8, and the water glass concentration is 30°~40°Be'. The gelling time is adjusted to 20sec~1min by adjusting the grouting material ratio.

[0034] In order to achieve the longitudinal continuity of the arch bearing body of the tunnel arch, the longitudinal lap length of the self-advanced anchor rod shall not be less than 2.0m.

[0035] In summary, the present invention realizes a process for pre-reinforcement of surrounding rock in advance for a dark-excavated tunnel passing through a limestone uneven weathering zone under the action of groundwater dissolution. The shear resistance of the surrounding rock is improved by anchor rods, thereby forming a combined arch structure in front of the tunnel face and outside the excavation contour line to realize pre-reinforcement of the surrounding rock. A high-strength finished hollow anchor rod body is used in combination with an alloy drill bit, a connecting sleeve, a grouting plug, an arch pad and a nut component to realize one-time and quick construction of drilling, grouting and anchoring. The anchor drilling equipment adopts a three-arm rock drilling trolley, which can realize fully mechanized drilling, pipe connection, and multi-pipe simultaneous operation. The mechanization degree is high, the construction operation efficiency is high, the operating workers can be away from the face, and the construction safety is higher.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A self-advanced grouting anchor advance support technology for a tunnel passing through a karst rock layer, characterized in that: The surrounding rock in front of the tunnel face is used as the main bearing body. A combined arch structure is formed above the tunnel face through a number of self-propelled grouting anchors arranged in a fan ring at a certain angle and a certain spacing, forming a lateral stress ring area along the excavation contour line, extending the unbalanced stratum stress above the tunnel face to the deep rock mass, forming an arch structure with the surrounding rock itself as the bearing body, and forming an advanced support system with the surrounding rock, anchor body and penetration grouting.

2. The self-advanced grouting anchor advance support technology for tunnels passing through karst rock layers according to claim 1 is characterized in that: The self-propelled grouting anchor drilling equipment adopts a three-arm rock drilling rig to realize mechanized operations of drilling, pipe connection, and multi-pipe connection at the same time.

3. The self-advanced grouting anchor advance support technology for tunnels passing through karst rock layers according to claim 1 or 2, characterized in that: The self-propelled grouting anchor comprises a hollow anchor rod body, a connecting sleeve, a drill bit, an arched pad, a nut and a grouting plug. The output end of the hollow anchor rod body is provided with a drill bit, which is also a hollow structure. The connecting sleeve is arranged between two sections of the hollow anchor rod body. The hollow anchor rod body close to the input end is provided with a grouting plug. The end of the hollow anchor rod body close to the input end is provided with the arched pad, and the other side of the arched pad is provided with a nut. Based on the self-propelled grouting anchor, drilling, grouting and anchoring can be conveniently constructed and supported in one go.

4. The self-advanced grouting anchor advance support technology for tunnels passing through karst rock layers according to claim 1 is characterized in that: The self-advanced grouting anchor rods are evenly arranged within 120° of the tunnel arch with the tunnel center as the central axis. The angle between the self-advanced grouting anchor rods and the longitudinal axis of the tunnel is 12° to 25°, forming an arch structure with a thickness of 1.5m to 3.5m on the excavation contour line within 120° of the tunnel arch.

5. The self-advanced grouting anchor advance support technology for tunnels passing through soluble rock layers according to claim 1 is characterized in that: The self-propelled grouting anchor rod performs grouting operation at the tail end after reaching the specified depth. When groundwater develops in the erosion stratum in front of the face, water glass can be added to the injected cement slurry to achieve rapid setting.

6. The self-advanced grouting anchor advance support technology for tunnels passing through karst rock layers according to claim 1 or 5, characterized in that: Before grouting, grouting tests and anchor and anchor body pull-out tests are carried out, and the cement slurry ratio is adjusted to achieve the best anchoring effect for the anchor body. When pore water is developed in the dissolution zone, water glass material is added to the cement slurry to form cement-water glass slurry. The water glass modulus m for grouting is between 2.4 and 2.8, and the water glass concentration is 30°~40°Be'. The gelling time is adjusted to 20sec~1min by adjusting the grouting material ratio.

7. The self-advanced grouting anchor advance support technology for tunnels passing through karst rock layers according to claim 1 is characterized in that: The longitudinal lap length of the self-advanced anchor shall not be less than 2.0m.

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