Drilling positioning and construction process for anchor and shotcrete support of soft rock underground engineering

Abstract

The application discloses a drilling positioning and construction process for anchor and shotcrete support of soft rock underground engineering, which comprises the following steps: S1, rock mass excavation; S2, steel fiber concrete spraying; S3, steel arch setting; S4, inner and outer layer steel mesh laying and pre-holing on the inner and outer layer steel mesh at positions where anchor rods / anchor pipes need to be drilled; S5, inserting a detachable casing at the inner and outer layer steel mesh with the pre-holes; S6, re-spraying; S7, removing the casing to form a directional hole for drilling the anchor rod / anchor pipe; and S8, filling the hole after drilling the anchor rod / anchor pipe in the hole and completing grouting and prestress application, and simultaneously serving as an embedded deformation monitoring point. The application reduces a process of spraying concrete, helps early support and early intervention in deformation control of surrounding rock, saves material cost, avoids abrasion caused by collision of a drill bit with a steel mesh, and saves drilling time.

Description

Technical Field

[0001] This application relates to the field of anchor spraying support technology for soft rock underground engineering, and in particular to a drilling positioning and construction process for anchor spraying support in soft rock underground engineering. Background Technology

[0002] In underground engineering projects such as soft rock tunnels and roadways constructed using the drill-and-blast method, anchor-sprayed support in composite lining is a necessary initial support method. After excavation of weak rock masses, the fresh rock surface is exposed and rapidly weathers due to factors such as moisture and vibration during construction. The combined support of anchor bolts / anchor bolts + steel mesh + shotcrete + steel frame in anchor-sprayed support can achieve early reinforcement of the rock mass and form a surface support force, working together with the surrounding rock to support and deform in tandem, reducing the load on the secondary lining. Previously, the typical workflow for anchor-sprayed support in underground engineering projects with weak surrounding rock was: excavation → anchor bolt positioning → initial shotcrete with mesh → installation of steel arch frame → secondary shotcrete → further shotcrete with mesh → drilling anchor bolts / anchor pipes and anchor plates → supplementary shotcrete. This required multiple shotcretes and drilling operations. With the increasing demands for clearance in underground engineering and the ever-increasing requirements for construction efficiency, the following problems with existing anchor-sprayed support have become increasingly prominent:

[0003] (1) When drilling anchor bolts / anchor pipes, it is necessary to pass through two layers of steel mesh. Blindly drilling is very likely to collide with the steel bars of the mesh and the intersection of the steel bars, which increases the wear of the drill bit and prolongs the drilling time.

[0004] (2) A single anchor-sprayed support operation cycle includes two drilling operations and four sprayed concrete operations, resulting in a long operation time and a large amount of sprayed concrete, which is not conducive to the early realization of the initial support closure ring effect.

[0005] (3) Although the final spraying was carried out, the phenomenon of exposed anchor heads still exists. The exposed anchor heads are easily bent and damaged during subsequent construction, affecting the anchoring effect. Moreover, the local protrusion of the initial support caused by the exposed anchor heads is not conducive to the tight bonding between the waterproof layer and the initial support, and is prone to puncture.

[0006] (4) The deformation observation points at the ends of the anchor bolts / anchor cables are exposed and are easily damaged by construction collisions and contamination, which can lead to interruption of deformation monitoring and incomplete deformation monitoring data. Summary of the Invention

[0007] To address the aforementioned issues, this application provides a drilling positioning and construction process for anchor-sprayed support in soft rock underground engineering. This reduces drill bit wear, saves drilling time, and significantly reduces time and material costs associated with sprayed concrete. It also facilitates early intervention in the initial support process to control the deformation of the surrounding rock. The technical solution is as follows:

[0008] This application provides a drilling positioning and construction process for anchor-sprayed support in soft rock underground engineering, including the following steps: S1, rock excavation; S2, spraying steel fiber reinforced concrete; S3, installing steel arch frame; S4, laying inner and outer layers of steel mesh and pre-reserving holes in the inner and outer layers of steel mesh at the locations where anchor rods / anchor pipes need to be drilled; S5, inserting detachable casings into the inner and outer layers of steel mesh with pre-reserved holes; S6, re-spraying; S7, removing the casing to form directional holes for drilling anchor rods / anchor pipes; S8, drilling anchor rods / anchor pipes in the holes and completing grouting and prestressing operations, then filling the holes and using them as embedded deformation monitoring points.

[0009] For example, in the drilling positioning and construction process of anchor spraying support for soft rock underground engineering provided in one embodiment, in step S4 of laying inner and outer steel mesh, the inner steel mesh is close to the free face and the outer steel mesh is close to the rock surface. The outer layer is laid first and then the inner layer is laid. The inner and outer steel meshes are welded to the two live sections of the two flanges on both sides of the steel arch frame, respectively.

[0010] For example, in the drilling positioning and construction process of anchor spraying support for soft rock underground engineering provided in one embodiment, in step S5, the two ends of the casing are sealed, and the position and number of the casing are consistent with the design of the anchor rod / anchor pipe.

[0011] For example, in the drilling positioning and construction process of anchor spraying support for soft rock underground engineering provided in one embodiment, in step S5, the casing is fixed with iron wire after being inserted into the reserved hole, or it is detachably connected to the outer steel mesh in advance, and the casing protrudes 2-3 cm from the surface of the sprayed concrete after re-spraying in step S6.

[0012] For example, in the drilling positioning and construction process of anchor spraying support for soft rock underground engineering provided in one embodiment, the casing is an irregularly shaped conical structure cylinder. After the casing is removed, the shape of the hole created leaves an arc surface, which provides line-of-sight guidance for the measurement station in the tunnel to observe the deformation of the anchor rod / anchor pipe end.

[0013] For example, in the drilling positioning and construction process of anchor spraying support for soft rock underground engineering provided in one embodiment, the side of the casing close to the rock surface can be set with an inclined surface as needed. That is, when drilling the advance anchor / small guide pipe, the casing is installed at an inclined angle according to the design inclination angle of the advance support, which creates a drilling position for the construction of the advance support and also serves as a deformation monitoring point.

[0014] For example, in the drilling positioning and construction process of anchor spraying support for soft rock underground engineering provided in one embodiment, in step S4, the size of the reserved hole is adapted to the size of the casing to facilitate the insertion of the casing.

[0015] For example, in the drilling positioning and construction process of anchor spraying support for soft rock underground engineering provided in one embodiment, in step S8, the hole is filled with mortar, wherein a wedge-shaped surface is reserved when filling the hole, that is, the hole that is not completely filled and sealed forms an embedded deformation observation point.

[0016] For example, in the drilling positioning and construction process of anchor spraying support for soft rock underground engineering provided in one embodiment, in step S3, the steel arch frame includes structural steel, grating steel frame and telescopic steel frame. When the telescopic steel frame is used, non-closed spraying is adopted during the re-spraying in step S6.

[0017] For example, in the drilling positioning and construction process of anchor spraying support for soft rock underground engineering provided in one embodiment, in step S6, the re-spraying adopts a layered and bottom-up spraying method, first spraying to fill the inside of the steel arch frame densely, and then spraying to the designed thickness.

[0018] The beneficial effects of the drilling positioning and construction technology for anchor-sprayed support in soft rock underground engineering provided by some embodiments of this application are as follows: Within a single excavation-anchor-sprayed support cycle, this application involves two spraying operations and one anchor / anchor pipe drilling operation. Compared to the traditional anchor-sprayed support process, this reduces the shotcrete step, saving significant time and material costs associated with shotcrete, and facilitating early intervention in the deformation control of the surrounding rock during initial support. Furthermore, by pre-reserving holes and using casing, the drill bit will no longer collide with the reinforcing steel during anchor / anchor pipe drilling, reducing drill bit wear. This design reduces drilling time and saves drilling time. While positioning the anchor bolt / anchor pipe borehole, the casing can also be used as an embedded deformation observation point by adjusting its shape, end face angle, installation angle, and the wedge-shaped surface design during borehole smoothing. Compared to exposed observation points, this is more stable, reliable, impact-resistant, and easier to observe. By adjusting the shape of one end of the casing and its installation angle, it can be used for positioning various types of boreholes, such as system anchor bolts and advanced support. The casing with caps at both ends in this application is reusable, has low cost, and can be directly penetrated during drilling operations even if it cannot be removed in time. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this specification or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a flowchart of the drilling location and construction process for anchor spraying support in soft rock underground engineering as described in this application.

[0021] Figure 2 This is a schematic diagram of the construction state structure of step S4 of this application;

[0022] Figure 3 This is a schematic diagram of the construction state structure of an embodiment of step S5 of this application;

[0023] Figure 4 This is a schematic diagram of the construction state structure of another embodiment of step S5 of this application;

[0024] Figure 5 This is a schematic diagram of the construction state structure of step S7 of this application. Detailed Implementation

[0025] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0026] Unless otherwise defined, the technical or scientific terms used in this disclosure shall have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms “first,” “second,” and similar terms used in this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as “comprising” or “including” mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as “connected” or “linked” are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as “upper,” “lower,” “left,” and “right” are used only to indicate relative positional relationships, and these relative positional relationships may change accordingly when the absolute position of the described objects changes.

[0027] This application provides a drilling positioning and construction process for anchor-sprayed support in soft rock underground engineering, such as... Figure 1 As shown, it includes the following steps:

[0028] S1, rock excavation;

[0029] S2, shotcrete with steel fiber reinforced concrete; steel fiber reinforced concrete itself has good crack resistance, eliminating the need for positioning anchors and wire mesh. Direct shotcrete with steel fiber reinforced concrete can quickly seal exposed rock excavation faces, reduce weathering, and save time. The thickness of the steel fiber reinforced concrete can be determined according to specifications and engineering experience. Uneven areas can be leveled with steel fiber reinforced concrete.

[0030] S3, Install steel arch frame 1; connect and fix it to the preceding steel arch frame by welding longitudinal connecting bars. As the main load-bearing structure, the early erection of steel arch frames can greatly reduce the operational risks to personnel and equipment. In the event of a large-area collapse, the steel arch frame can play a good protective role.

[0031] S4, as Figure 2 As shown, inner and outer steel mesh 2 are laid, and larger holes 3 are reserved on the inner and outer steel mesh at the locations where anchor rods / anchor pipes need to be drilled;

[0032] S5, such as Figure 3 or Figure 4 As shown, a detachable protective sleeve 4 is inserted into the inner and outer steel mesh 2 with pre-reserved holes 3. Figure 3 The image shows a straight steel arch frame, typically used in tunnels. Figure 4 The image shows a curved steel arch frame, typically used in highway or railway tunnels.

[0033] S6, double spraying;

[0034] S7, such as Figure 5 As shown, the casing 4 is removed and hardened with sprayed concrete to form a hole 5 for drilling anchor bolts / anchor pipes. The anchor bolts / anchor pipes can be drilled directly without colliding or intersecting with the steel mesh. After the re-spraying operation is completed, the casing is removed in time for recycling.

[0035] S8, after drilling anchor rods / anchor pipes into the hole and completing grouting and prestressing operations, the hole is filled and also serves as an embedded deformation monitoring point.

[0036] This concludes one cycle of excavation and shotcrete support. The drilling positioning and construction technology for shotcrete support in soft rock underground engineering described in this application involves two shotcrete operations and one anchor / anchor pipe drilling operation within a single excavation-shotcrete support cycle. Compared to the traditional shotcrete support process, this eliminates one shotcrete step, saving significant time and material costs associated with shotcrete. It also facilitates early intervention in the initial support process to control surrounding rock deformation. Furthermore, by pre-drilling holes and using casing, the drill bit will not collide with the reinforcing steel during anchor / anchor pipe drilling, reducing drill bit wear. Wear and tear reduces drilling time; while positioning the anchor bolt / anchor pipe borehole, the casing can also be used as an embedded deformation observation point by adjusting its shape, end face angle, installation angle, and wedge-shaped surface design during borehole smoothing. Compared to exposed observation points, it is more stable, reliable, impact-resistant, and easier to observe; by adjusting the shape of one end of the casing and its installation angle, it can be used for positioning various types of boreholes such as system anchor bolts and advanced support; the casing with caps at both ends in this application can be reused, is low in cost, and can be directly penetrated during drilling operations even if it cannot be removed in time.

[0037] For example, in the drilling positioning and construction process of anchor spraying support for soft rock underground engineering provided in one embodiment, in step S4 of laying inner and outer steel mesh, the inner steel mesh is close to the free face and the outer steel mesh is close to the rock surface. The outer layer is laid first and then the inner layer is laid. The inner and outer steel meshes are welded to the two live sections of the two flanges on both sides of the steel arch frame, respectively.

[0038] For example, in the drilling positioning and construction process of anchor spraying support for soft rock underground engineering provided in one embodiment, in step S5, the casing is a smooth casing with caps at both ends and a sealed end, which can be round or square, and the position and number of casings are consistent with the design of anchor rods / anchor pipes.

[0039] For example, in the drilling positioning and construction process of anchor spraying support for soft rock underground engineering provided in one embodiment, in step S5, the casing is fixed with iron wire after being inserted into the reserved hole, or it is detachably connected to the outer steel mesh in advance, and the length of the casing is 2-3 cm protruding from the surface of the sprayed concrete after re-spraying in step S6.

[0040] For example, in the drilling positioning and construction process of anchor spraying support for soft rock underground engineering provided in one embodiment, the casing can be made of plastic or other special-shaped conical structures according to operational needs. After the casing is removed, the hole shape created leaves an arc surface, which provides line guidance for the deformation observation of the anchor rod / anchor pipe end by the tunnel monitoring station, thus facilitating the needs of deformation observation.

[0041] For example, in the drilling positioning and construction process of anchor spraying support for soft rock underground engineering provided in one embodiment, the side of the casing close to the rock surface can be set with an inclined surface as needed. That is, when drilling the advance anchor / small guide pipe, the casing is installed at an inclined angle according to the design inclination angle of the advance support, which creates a drilling position for the construction of the advance support and also serves as a deformation monitoring point.

[0042] For example, in the drilling positioning and construction process of anchor spraying support for soft rock underground engineering provided in one embodiment, in step S4, the size of the reserved hole is adapted to the size of the casing, which facilitates the insertion of the casing and meets the requirements of the anchor plate size of the anchor rod / anchor pipe and the drilling rig operating space. The depth of the reserved hole is slightly greater than the design thickness of the initial support.

[0043] For example, in the drilling positioning and construction process of anchor spraying support for soft rock underground engineering provided in one embodiment, in step S8, the hole is filled with mortar to protect the anchor head. When filling the hole, leveling is not required, and a wedge-shaped surface is appropriately left. That is, the hole that is not completely filled and sealed can form an embedded deformation observation point, which is more stable, reliable and impact-resistant than an exposed observation point. When leveled, it is made into a wedge-shaped surface, which facilitates the visual guidance and observation of technicians inside the tunnel.

[0044] For example, in the drilling positioning and construction process of anchor spraying support for soft rock underground engineering provided in one embodiment, in step S3, the steel arch frame includes, but is not limited to, structural steel, grid steel frame and telescopic steel frame. When a telescopic steel frame is used, non-closed spraying is adopted during the re-spraying in step S6. It is not allowed to spray and close the frame to avoid the steel frame structure from losing its extensibility.

[0045] For example, in the drilling positioning and construction process of anchor spraying support for soft rock underground engineering provided in one embodiment, in step S6, because the thickness of the first spray is large, the re-spraying adopts a layered method and sprays from bottom to top. First, the inside of the steel arch frame is sprayed and filled densely, and then sprayed to the designed thickness.

[0046] Although the embodiments of this application have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for this application. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, this application is not limited to the specific details and the illustrations shown and described herein.

Claims

1. A drilling positioning and construction technology for anchor-sprayed support in soft rock underground engineering, characterized in that, Includes the following steps: S1, rock excavation; S2, sprayed steel fiber reinforced concrete; S3, Install steel arch frame; S4, Lay inner and outer steel mesh and reserve holes in the inner and outer steel mesh at the locations where anchor rods / anchor pipes need to be drilled; S5, insert a detachable protective sleeve into the inner and outer steel mesh with reserved holes; S6, double spraying; S7, Remove the casing to form a directional hole for drilling anchor bolts / anchor pipes; S8, after drilling anchor rods / anchor pipes into the hole and completing grouting and prestressing operations, the hole is filled and also serves as an embedded deformation monitoring point; The casing is an irregularly shaped conical cylinder. After the casing is removed, the resulting cavity has an arc-shaped surface, which provides visual guidance for the tunnel station to observe the deformation of the anchor rod / anchor pipe end.

2. The drilling positioning and construction technology for anchor-sprayed support in soft rock underground engineering according to claim 1, characterized in that, In step S4, when laying the inner and outer layers of steel mesh, the inner layer of steel mesh is close to the free surface, and the outer layer of steel mesh is close to the rock surface. The outer layer is laid first, and then the inner layer is laid. The inner and outer layers of steel mesh are welded to the two live sections of the two flanges on both sides of the steel arch frame, respectively.

3. The drilling positioning and construction technology for anchor-sprayed support in soft rock underground engineering according to claim 1, characterized in that, In step S5, the two ends of the casing are sealed, and the position and number of casings installed are consistent with the design of the anchor rod / anchor pipe.

4. The drilling positioning and construction technology for anchor-sprayed support in soft rock underground engineering according to claim 3, characterized in that, In step S5, the casing is fixed with wire after being inserted into the reserved hole, or it is detachably connected to the outer steel mesh beforehand, and the casing protrudes 2-3 cm from the sprayed concrete surface after the re-spraying in step S6.

5. The drilling positioning and construction technology for anchor-sprayed support in soft rock underground engineering according to claim 1, characterized in that, The casing can be inclined on the side close to the rock surface as needed. That is, when drilling the advance anchor / small guide pipe, the casing is installed at an angle according to the design inclination of the advance support, which creates drilling positions for the advance support and also serves as a deformation monitoring point.

6. The drilling positioning and construction technology for anchor-sprayed support in soft rock underground engineering according to claim 1, characterized in that, In step S4, the size of the reserved hole is matched with the size of the casing to facilitate the insertion of the casing.

7. The drilling positioning and construction technology for anchor-sprayed support in soft rock underground engineering according to claim 1, characterized in that, In step S8, the cavity is filled with mortar, wherein a wedge-shaped surface is reserved during the filling of the cavity, that is, the cavity that is not completely filled and closed forms an embedded deformation observation point.

8. The drilling positioning and construction technology for anchor-sprayed support in soft rock underground engineering according to claim 1, characterized in that, In step S3, the steel arch frame includes structural steel, grating steel frame and telescopic steel frame. When the telescopic steel frame is used, non-enclosed spraying is adopted during the re-spraying in step S6.

9. The drilling positioning and construction technology for anchor-sprayed support in soft rock underground engineering according to claim 1, characterized in that, In step S6, the re-spraying adopts a layered and bottom-up spraying method, first spraying the inside of the steel arch frame to fill it densely, and then spraying to the designed thickness.

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