A method for initial support construction of a tunnel crossing a water-rich fault zone

Abstract

This application relates to a method for initial tunnel support construction across a water-rich fault zone, belonging to the field of tunnel support construction technology. The method comprises the following steps: S1, initial shotcreting; S2, surveying and setting out anchor hole locations and marking them; using a drilling guide to direct the holes perpendicular to the rock surface at the marked locations; using a drill tool to drill the anchor holes under the guidance of the drilling guide; and after the holes are cleaned, grouting with hollow anchor rods; S3, attaching a steel mesh; S4, installing a steel frame and securing it with longitudinal connecting steel bars; and S5, re-shotcreting. This application improves the effectiveness of combined anchor and shotcrete support.

Description

Technical Field

[0001] The present application relates to the field of tunnel support construction technology, and in particular to a method for initial tunnel support construction that passes through a water-rich fault structural zone. Background Art

[0002] During tunnel excavation, the inner wall of the tunnel needs to be supported simultaneously to prevent mountain collapse. Conventional support construction usually adopts the New Austrian Tunneling Method (NATM), which is based on tunnel engineering experience and rock mechanics theory. It combines anchor rods and shotcrete as the main support means.

[0003] In actual support construction, a large number of radial anchor rods are needed. However, since the tunnel cross-section is mostly arc-shaped, it is difficult to control the verticality of the drill hole when constructing radial anchor rods. If the anchor rod is not perpendicular to the surrounding rock surface and the angle deviation is large, it will seriously affect the anchoring effect of the anchor rod, thereby reducing the effect of the anchor-spraying combined support. Summary of the Invention

[0004] In order to improve the effect of bolt-spray combined support, the present application provides a method for initial support construction of a tunnel passing through a water-rich fault structural zone.

[0005] The present application provides a method for initial support construction of a tunnel crossing a water-rich fault zone, which adopts the following technical solution:

[0006] A method for initial support construction of a tunnel passing through a water-rich fault zone comprises the following steps: S1, initial spraying of concrete; S2, measuring and setting out anchor hole positions and marking them, drawing a line perpendicular to the rock surface at the marked position using a drilling guide device, drilling the anchor holes using a drill tool under the guidance of the drilling guide device, and grouting with hollow anchor rods after the holes are cleaned; S3, hanging a steel mesh; S4, installing a steel frame and securing the steel frame with longitudinal connecting steel bars; and S5, re-spraying of concrete.

[0007] By adopting the above technical solution, the drilling guide device guides the drilling tool, improves the accuracy of the anchor hole position, ensures the anchoring effect of the anchor, and improves the anchor-spraying combined support effect.

[0008] Optionally, in step 2, high-pressure air is used to blow out sand, gravel and other debris in the anchor hole, and the drilling depth is checked. The hole depth deviation is no more than 50 mm.

[0009] By adopting the above technical solution, the influence of debris in the hole on the strength of concrete after solidification is reduced after the hole is cleaned, which is conducive to increasing the anchoring effect and positioning accuracy of the anchor rod.

[0010] Optionally, in step S3, the steel mesh is welded to the anchor rods and fixed, and a longitudinal overlap length of not less than 35d is reserved after the steel mesh is constructed.

[0011] By adopting the above technical solution, the steel mesh is fixed, which increases its stability during the subsequent concrete spraying process; the reserved overlap length of the steel mesh facilitates the connection of the subsequent steel mesh, thereby improving the stability of the entire support.

[0012] Optionally, in step S4, the steel frame is installed in sections, each section is formed by welding I-beams and connecting steel plates, and adjacent sections are fixed with bolts.

[0013] By adopting the above technical solution, the steel frame is divided into multiple segments, which is convenient for production and transportation on the one hand, and convenient for adjusting the position of each segment to match the tunnel side wall during installation on the other hand.

[0014] Optionally, in step S4, a wedge is set in the gap between the steel frame and the initial sprayed surface, the steel frame footing is reinforced with concrete, and locking anchor rods are set on both sides of the steel frame for fixing.

[0015] By adopting the above technical solution, the wedge blocks, foundation reinforcement and locking anchor rods play a role in fixing the steel frame, thereby increasing the overall stability of the steel frame.

[0016] Optionally, the drilling guide device in step S2 includes two first support rods, the two first support rods are hinged by a first core shaft, the two first support rods are fixed with a second support rod at one end close to the first core shaft, the two second support rods are hinged with a third support rod at one end away from the first core shaft, the two third support rods are hinged to each other by the second core shaft, the two second support rods and the two third support rods form a kite shape, a guide column is rotatably connected to the first core shaft, a guide sleeve for inserting the guide column is rotatably connected to the second core shaft, a drill sleeve is provided on the guide column, and the axis of the drill sleeve is parallel to the guide column.

[0017] By adopting the above technical solution, the operator places the two first support rods in the vertical direction and places the hinged ends of the two first support rods next to the marking point. At the same time, the drill sleeve is aligned with the marking point, and the ends of the two first support rods away from the first core shaft are adjusted to abut against the inner wall of the tunnel. At this time, the guide column is on the mid-vertical line of the marking point. The drill rod of the drill tool is inserted into the guide sleeve and drilling is carried out, which reduces the possibility of drilling position deviation.

[0018] Optionally, it also includes a construction platform and an arch frame, wherein the construction platform is located on the inner side of the arch frame, and the arch frame is provided with a guide plate distributed along its outer contour, and a holder is inserted into the guide plate, and the holder is fixed to the guide plate by a limiting member, so a screw barrel is provided on the side wall of the holder, and an adjusting rod is passed through the screw barrel, and a waist-shaped groove is provided on the adjusting rod for the screw barrel to pass through, and one end of the screw barrel passing through the waist-shaped groove is threadedly connected to a limiting ring, and a clamping frame is provided on the end of the adjusting rod away from the screw barrel, and the guide column is inserted into the clamping frame and the clamping frame is fixed to the guide column by bolts.

[0019] By adopting the above technical solution, the drilling guide device is based on the arch frame, and the waist-shaped groove provides the adjustment rod with adjustment space in terms of angle and distance. When fixing, the operator can clamp the guide column by twisting the limit ring, which facilitates the operator to move the position to guide the drilling of different marking points, thereby improving the flexibility of the device.

[0020] Optionally, the limiting member includes a stud and an end cap, the stud is located in the screw barrel, one end of the stud is threadedly connected to the holder, and the other end is coaxially fixed with a spline, and the spline passes through the end cap, and the side wall of the limiting ring is connected to an intermediate sleeve, and the end of the intermediate sleeve away from the limiting ring is fixed with an external gear sleeve, and the external gear sleeve is inserted in the end cap, and the inner wall of the end cap is provided with an inner gear ring meshing with the external gear sleeve.

[0021] By adopting the above technical solution, the operator rotates the end cap, which simultaneously drives the spline and the inner gear ring to rotate, causing the stud and the limit ring to rotate, the stud advances and presses against the guide plate, and the limit ring presses the adjusting rod against the other limit ring, thereby achieving simultaneous fixation of the adjusting rod and the holder, which is convenient and quick; when the stud advances but does not reach its position, the operator moves the end cap backward to disengage the inner gear ring and the outer gear sleeve, and rotates the end cap to drive the spline to rotate alone, driving the stud to press against the guide plate.

[0022] Optionally, one end of the spline passing through the end cap is connected to a stopper, and when the end cap abuts against the stopper, the outer gear sleeve is separated from the inner gear ring.

[0023] By adopting the above technical solution, the block plays a role in limiting the moving position of the spline, saving the operator time in adjusting the position of the end cap.

[0024] Optionally, an adjusting screw is threadedly connected to the guide sleeve, the adjusting screw passes into the guide sleeve and a steel ball is embedded in one end of the adjusting screw, and the steel column abuts against the guide column.

[0025] By adopting the above technical solution, the operator can adjust the pressure applied by the steel ball to the guide column by turning the adjustment screw, thereby adjusting the resistance encountered by the guide column when moving, making it easier for the operator to fix the position of the first support rod.

[0026] In summary, this application includes at least one of the following beneficial technical effects:

[0027] 1. The drilling guide device guides the drilling tool, increases the accuracy of the anchor hole position, and improves the effect of the anchor-spraying combined support;

[0028] 2. The simultaneous fixation and release of the adjustment rod and the clamping seat are achieved, which provides convenience for the operator to use the drilling guide device. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the overall structure of an embodiment of the present application.

[0030] Figure 2 It is a structural diagram of the embodiment of the present application used to reflect the arch frame and construction platform.

[0031] Figure 3 yes Figure 2 Enlarged view of point A in the middle.

[0032] Figure 4 It is a schematic diagram of the structure of the adjusting screw used in the embodiment of the present application.

[0033] Figure 5 It is a structural diagram of a restriction member used in an embodiment of the present application.

[0034] Figure 6 It is an exploded schematic diagram used to illustrate the barrel and stud in the embodiment of the present application.

[0035] Explanation of the accompanying reference numerals: 11. First support rod; 111. First core shaft; 12. Second support rod; 13. Third support rod; 131. Second core shaft; 14. Guide column; 141. Drill sleeve; 15. Guide sleeve; 16. Adjusting screw; 161. Steel ball; 2. Construction platform; 3. Arch frame; 31. Guide plate; 32. Clamping seat; 33. Screw barrel; 34. Adjusting rod; 341. Waist groove; 35. Limiting ring; 36. Clamping frame; 4. Limiting member; 41. Stud; 411. Spline; 42. End cap; 421. Inner gear ring; 43. Intermediate sleeve; 431. Outer gear sleeve; 44. Stop block. DETAILED DESCRIPTION

[0036] The following is combined with Figure 1-6 This application is described in further detail.

[0037] The present application discloses a method for initial support construction of a tunnel crossing a water-rich fault zone. The method comprises the following steps: S1. After tunnel excavation and slag removal, dangerous rocks are removed and the section is inspected for over-excavation. After passing the inspection, initial concrete spraying is performed. The concrete spraying adopts a wet spraying process and the thickness is controlled at 4-6 cm.

[0038] S2. Measure and determine the anchor hole position and mark it. Use the drilling guide device to draw the direction perpendicular to the rock surface at the mark. Use the drill tool to drill the anchor hole under the guidance of the drilling guide device. The drill hole should be round and straight, the rock at the hole mouth should be leveled and the rock surface should be perpendicular to the drilling direction. Use high-pressure air to blow out sand and gravel and other debris in the anchor hole. After completing the hole cleaning operation, check the drilling depth. The hole depth deviation should not exceed 50mm. Use a hollow anchor rod for grouting. When grouting, insert the hollow anchor rod into the anchor hole. The tail end of the anchor rod is exposed 10cm from the hole mouth. Set a grouting plug and reserve an exhaust port. Put a pad on the tail end of the anchor rod, and then tighten the nut. Use a screw grouting pump dedicated to the anchor rod to pressurize cement slurry into the hollow anchor rod. Stop grouting after slurry comes out of the exhaust port.

[0039] S3. Hang the steel mesh. The steel mesh uses φ8 steel bars. According to the design drawings and the longitudinal excavation length of the tunnel, the mesh is made in the steel processing plant and the steel bars are connected into a mesh by spot welding. During installation, the steel mesh should be laid along the undulations of the initial spraying surface. When the initial spraying surface undulates too much, proper leveling should be performed to ensure that the distance between the steel mesh and the initial spraying surface is within 2-3cm. The steel mesh is welded and fixed to the anchor rod to ensure that the steel mesh does not shake during concrete spraying. After the steel mesh construction is completed, the reserved longitudinal lap length shall not be less than 35d (d is the diameter of the steel bar) and shall not be less than the long side size of one grid.

[0040] S4. Install the steel frame. The steel frame is installed in sections. Each section is welded by I-beams and connecting steel plates. Adjacent sections are fixed with bolts. The steel frame is fixed with longitudinal connecting steel bars. Locking anchor rods are set on both sides of the steel frame for fixation. The footing of the steel frame is reinforced with concrete, or 0.15-0.2m of original foundation is reserved at the foot of the steel frame during construction. When the steel frame is erected, a groove is dug in place. Channel steel is set at the foot of the steel frame in weak areas to increase the base bearing capacity. If there is a large gap between the steel frame and the initial sprayed surface after installation, wedge blocks should be set in the gap between the steel frame and the initial sprayed surface to enhance the overall stability of the steel frame.

[0041] S5. Re-spray concrete; the spraying sequence is from bottom to top, first the wall foot then the wall top, first the arch foot then the arch top, the movement trajectory of the sprayed material beam is a longitudinal snake-shaped rotation, one circle for half a circle, and the spraying operation is carried out in layers according to thickness. The latter layer should be sprayed after the previous layer of concrete has finally set. If the interval after final setting is more than 1 hour and the surface of the initial spraying is covered with dust, the sprayed surface should be cleaned with high-pressure wind and water.

[0042] The drilling guiding device includes a construction platform 2, an arch support 3, and two first struts 11. The two first struts 11 are of the same length and their ends are hinged by a first core shaft 111. At one end of each of the two first struts 11 close to the first core shaft 111, a second strut 12 is fixed. The two second struts 12 are of the same length and cross each other, and the included angle between each second strut 12 and its corresponding first strut 11 is an obtuse angle with the same degree. At one end of each of the two second struts 12 far from the first core shaft 111, a third strut 13 is hinged. The two third struts 13 are of the same length. At one end of each of the two third struts 13 far from their corresponding second struts 12, they are hinged by a second core shaft 131. The first strut 11, the second strut 12, and the third strut 13 form a kite shape, and the connection line between the first core shaft 111 and the second core shaft 131 is the diagonal of the kite shape; a guide post 14 is rotatably connected to the first core shaft 111, and a guide sleeve 15 is rotatably connected to the second core shaft 131. The guide post 14 is coaxially inserted into the guide sleeve 15 and the axes of both are located on the connection line between the first core shaft 111 and the second core shaft 131. A drill sleeve 141 is fixed to the side wall of the guide post 14 by screws, and the axis of the drill sleeve 141 is parallel to the axis of the guide post 14.

[0043] A regulating screw 16 is threadedly connected to the guide sleeve 15. The regulating screw 16 vertically penetrates into the guide sleeve 15, and at the penetrated end, a steel ball 161 is embedded. The steel ball 161 can freely rotate and abuts against the guide post 14. An operator can turn the regulating screw 16 to adjust the abutting force between the steel ball 161 and the guide post 14, increasing the resistance to the relative movement between the guide post 14 and the guide sleeve 15, thereby maintaining the shape of the formed kite shape.

[0044] The construction platform 2 is built with a scaffold and steel plates and is used to provide a support foundation for construction workers. The arch support 3 is erected outside the construction platform 2 and is fixed in a form of multi-segment splicing. The outer contour of the arch support 3 is adapted to the inner contour of the tunnel and there is a spacing between the two. Guide plates 31 are provided on the outer contour of the arch support 3. A clamping seat 32 is inserted into the guide plate 31. The clamping seat 32 can move along the guide plate 31 and is fixed to the guide plate 31 by a limiting member 4. A screw cylinder 33 is vertically provided on the side wall of the clamping seat 32. An adjusting rod 34 penetrates through the screw cylinder 33. A waist-shaped slot 341 for the screw cylinder 33 to pass through is provided on the adjusting rod 34. The waist-shaped slot 341 is distributed along the length direction of the adjusting rod 34, enabling the adjusting rod 34 to freely rotate and move within a certain range. Limiting rings 35 are threadedly connected to both sides of the adjusting rod 34 on the screw cylinder 33, and the two limiting rings 35 clamp the adjusting rod 34 to fix the adjusting rod 34; at one end of the adjusting rod 34 far from the screw cylinder 33, a clamping frame 36 is provided. The clamping frame 36 is in a U shape and the opening faces away from the adjusting rod 34. The guide post 14 is inserted into the clamping frame 36 and they are fixed by bolts. The adjusting rod 34 is parallel to the guide post 14, and the two first struts 11 are arranged vertically one above the other.

[0045] The limiting member 4 includes a stud 41 and an end cap 42. The stud 41 is coaxially inserted into the screw barrel 33. One end of the stud 41 is threadedly connected to the base 32 and passes through the base 32 to abut against the guide plate 31. The other end is coaxially fixed with a spline 411. The end cap 42 is sleeved on the end of the screw barrel 33 away from the base 32. The inner diameter of the end cap 42 is larger than the outer diameter of the screw barrel 33. The spline 411 passes through the end cap 42, and the end passing through is connected to a stopper 44. The end cap 42 is provided with a spline 411. 11 matches the spline 411 hole; an intermediate sleeve 43 is provided on the side of the limiting ring 35 facing the end cap 42, the inner wall of the intermediate sleeve 43 is in contact with the screw barrel 33, and an outer gear sleeve 431 is fixed on the outer peripheral wall of the intermediate sleeve 43 away from the end of the limiting ring 35. The outer gear sleeve 431 is inserted into the end cap 42, and an inner gear ring 421 that meshes with the outer gear sleeve 431 is provided on the inner peripheral wall of the end cap 42. When the end cap 42 abuts against the stop block 44, the outer gear sleeve 431 and the inner gear ring 421 are separated.

[0046] The hinged ends of the two first support rods 11 are denoted as f, the two ends of the first support rods 11 away from the first core axis 111 are g and h respectively, and the second core axis 131 is denoted as w; when the drilling point is marked, the operator sets up the construction platform 2 and the arch frame 3, moves the clamping seat 32 close to the marking point, and moves the adjusting rod 34 so that the f end abuts the position of the marking point staggered along the axial direction of the tunnel to ensure that the drill sleeve 141 corresponds to the marking point, and then adjusts the g end and the h end to abut against the inner wall of the tunnel according to the curvature of the inner wall of the tunnel. In this process, the operator adaptively adjusts the position of the clamping seat 32 and the angle of the adjusting rod 34, and finally ensures that the three points of f end, g end and h end abut against the inner wall of the tunnel at the same time, and the three points f, g and h form an isosceles triangle, and the inner wall of the tunnel is the circumcircle of the isosceles triangle. Any triangle has and only has one circumcircle, and the center of the circumcircle is the intersection of the perpendicular bisectors of the three sides of the triangle. Therefore, the perpendicular bisector of the gh side of the isosceles triangle is through The tangent line of the drill sleeve 141 passes through point f and is perpendicular to the tangent line of point f. At the same time, the perpendicular midline of the side gh is collinear with the diagonal line of the kite fw. The diagonal line fw is parallel to the axis of the drill sleeve 141. Therefore, the axis of the drill sleeve 141 is perpendicular to the rock surface. After the adjustment is completed, the operator screws the end cap 42, and the end cap 42 drives the inner gear ring 421 and the spline 411 to rotate synchronously. The inner gear ring 421 drives the outer gear sleeve 431 to rotate. The outer gear sleeve 431 adjusts the limit ring 35 through the intermediate sleeve 43 to rotate, so that the limit The ring 35 is close to the adjusting rod 34, and at the same time the spline 411 drives the stud 41 to rotate, so that the stud 41 is close to the guide plate 31. When the limiting ring 35 presses the adjusting rod 34 tightly, the stud 41 and the guide plate 31 are pressed tightly, thereby achieving the simultaneous fixation of the adjusting rod 34 and the holder 32. Some studs 41 have not moved into place, and the operator moves the end cap 42 backward to abut against the stop block 44, so that the inner gear ring 421 is disengaged from the outer gear sleeve 431, and the end cap 42 is rotated again to tighten the stud 41.

[0047] The operator inserts the drill bit of the drilling rig into the drill sleeve 141 and drills with the help of the drill sleeve 141, which improves the position accuracy of the drilling hole and helps to enhance the anchoring effect after the hollow anchor grouting construction, thereby improving the anchor-spraying combined support effect.

[0048] The above are all preferred embodiments of the present application, and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A method for initial support construction of a tunnel passing through a water-rich fault zone, characterized in that The process includes the following steps: S1, initial spraying of concrete; S2, measuring and setting out the anchor hole positions and marking them; using a drilling guide to drill the anchor hole perpendicular to the rock surface at the marked position; using a drill tool under the guidance of the drilling guide; and grouting the hole with a hollow anchor rod after cleaning; S3, hanging a steel mesh; S4, installing a steel frame and fixing the steel frame with longitudinal connecting steel bars; S5, re-spraying of concrete; The drilling guide device in step S2 includes two first support rods (11), the two first support rods (11) are hinged through a first core shaft (111), the two first support rods (11) are fixed with a second support rod (12) at one end close to the first core shaft (111), the two second support rods (12) are hinged with a third support rod (13) at one end away from the first core shaft (111), the two third support rods (13) are hinged to each other through a second core shaft (131), the two second support rods (12) and the two third support rods (13) form a kite shape, a guide column (14) is rotatably connected to the first core shaft (111), a guide sleeve (15) for inserting the guide column (14) is rotatably connected to the second core shaft (131), a drill sleeve (141) is provided on the guide column (14), and the axis of the drill sleeve (141) is parallel to the guide column (14); The utility model also includes a construction platform (2) and an arch frame (3), wherein the construction platform (2) is located on the inner side of the arch frame (3), and the arch frame (3) is provided with a guide plate (31) distributed along its outer contour, and a holder (32) is inserted into the guide plate (31), and the holder (32) is fixed to the guide plate (31) by a limiting member (4), so a screw barrel (33) is provided on the side wall of the holder (32), and an adjusting rod (34) is passed through the screw barrel (33), and a waist-shaped groove (341) for the screw barrel (33) to pass through is opened on the adjusting rod (34), and the screw barrel (33) is threadedly connected to a limiting ring (35) on both sides of the adjusting rod (34), and a clamping frame (36) is provided at one end of the adjusting rod (34) away from the screw barrel (33), and the guide column (14) is inserted into the clamping frame (36), and the clamping frame (36) is fixed to the guide column (14) by bolts.

2. The method for initial support construction of a tunnel passing through a water-rich fault zone according to claim 1, characterized in that: Use high-pressure air to blow out sand, gravel and other debris in the anchor hole when cleaning the hole, check the drilling depth, and the hole depth deviation should not exceed 50mm.

3. The method for initial support construction of a tunnel passing through a water-rich fault zone according to claim 1, characterized in that: In step S3, the steel mesh is welded to the anchor rod and fixed. After the steel mesh is constructed, a longitudinal overlap length of not less than 35d is reserved.

4. The method for initial support construction of a tunnel passing through a water-rich fault zone according to claim 1, characterized in that: In step S4, the steel frame is installed in sections, each section is formed by welding I-beams and connecting steel plates, and adjacent sections are fixed with bolts.

5. The method for initial support construction of a tunnel passing through a water-rich fault zone according to claim 4, characterized in that: In step S4, a wedge is set in the gap between the steel frame and the initial sprayed surface, the steel frame footing is reinforced with concrete, and locking anchor rods are set on both sides of the steel frame for fixing.

6. The method for initial support construction of a tunnel passing through a water-rich fault zone according to claim 1, characterized in that: The limiting member (4) includes a stud (41) and an end cap (42), wherein the stud (41) is located in the screw barrel (33), one end of the stud (41) is threadedly connected to the holder (32), and the other end is coaxially fixed with a spline (411), and the spline (411) passes through the end cap (42), and the side wall of the limiting ring (35) is connected to an intermediate sleeve (43), and the end of the intermediate sleeve (43) away from the limiting ring (35) is fixed with an outer gear sleeve (431), and the outer gear sleeve (431) is inserted into the end cap (42), and the inner wall of the end cap (42) is provided with an inner gear ring (421) meshing with the outer gear sleeve (431).

7. The method for initial support construction of a tunnel passing through a water-rich fault zone according to claim 6, characterized in that: One end of the spline (411) passing through the end cap (42) is connected to a stopper (44); when the end cap (42) abuts against the stopper (44), the outer gear sleeve (431) is separated from the inner gear ring (421).

8. The method for initial support construction of a tunnel passing through a water-rich fault zone according to claim 1, characterized in that: The guide sleeve (15) is threadedly connected with an adjusting screw (16), which penetrates into the guide sleeve (15) and has a steel ball (161) embedded in one end of the adjusting screw (16), and the steel ball (161) abuts against the guide column (14).

Images