Construction method of large pipe roof guide wall at shallow tunnel opening

Abstract

This is a construction method for large pipe roof guide walls at the opening of a shallow buried tunnel. [Solution] The construction method of a large pipe roof guide wall at a shallow-buried tunnel opening includes step S1 of transporting a construction device to a predetermined location and performing drawing lofting, step S2 of positioning and excavating the guide wall (1) at a predetermined location, and reserving the deformation amount of the tunnel opening based on the properties of the surrounding rock, step S3 of attaching an inner contour stencil and a positioning arch (3) for the guide wall (1), step S4 of determining the outsert angle of the pipe roof based on the properties of the surrounding rock, step S5 of installing and adjusting the orifice pipe (2) and then installing an end head stencil and a hoop stencil for the guide wall (1), and step S6 of pouring concrete for the guide wall (1) until it reaches a predetermined strength, and performing maintenance after pouring is completed. This method determines the outsert angle of the orifice pipe of the pipe roof guide wall, and uses the outsert angle of the guide tube to position the pipe roof (4), avoiding the need to enter the positive hole and excavate the contour line during excavation construction, making the angle calculation accurate, the construction convenient, ensuring the reinforcing effect of the large pipe roof, and realizing the safe entry of the tunnel into the opening.

Description

Technical Field

[0001] The present invention belongs to the technical field of tunnel process technology, and specifically relates to a construction method for a large pipe roof guide wall at the opening of a shallow-buried tunnel.

Background Art

[0002] Pipe roof support is a frequently used advanced support when a tunnel passes through poor geological areas such as soft, loose, fractured rock masses, and quicksand. The guide wall, as a guide and fixing facility for long pipe roof construction, can play a guiding role while also supporting the pipe roof to improve the force-bearing of the pipe roof, and its accuracy directly affects the accuracy of the pipe roof drilling and the support effect. In pipe roof construction, determining the outsert angle of the guide tube is extremely important. If the selected outsert angle is not appropriate, it will directly affect the progress of subsequent construction. If the outsert angle is too small, it is easy for the pipe roof to penetrate into the correct hole and excavate the contour line, and it takes a lot of time to cut the steel pipe that has penetrated into the contour line using an electric welding machine after excavation, increasing the construction cost and at the same time affecting the construction quality of the pipe roof. If the outsert angle is too large, it will reduce the effective utilization rate of grout injection, and the pipe roof cannot effectively control over-excavation, and its auxiliary effect on the stability of the tunnel hole rock and soil layer structure is not significant.

[0003] Therefore, it is necessary to provide a technical solution to improve the above deficiencies of the prior art.

Summary of the Invention

Problems to be Solved by the Invention

[0004] The object of the present invention is to overcome the deficiencies in the above prior art and provide a construction method for a large pipe roof guide wall at the opening of a shallow-buried tunnel.

Means for Solving the Problems

[0005] In order to achieve the above object, the present application provides the following technical means.

[0006] Transport the construction device to a predetermined position, Drawing development and perform step S1; Position and excavate the guide wall at a preset position, and determine the deformation amount of the tunnel opening based on the properties of the surrounding rock Estimate Step S2; Step S3 of attaching the inner contour stencil and positioning arch of the guide wall; Based on the properties of the surrounding rock, Insert Determine the angle of the pipe roof, and calculate the angle of the orifice pipe based on the distance at the location where the guide wall is located in step S4; After attaching and adjusting each orifice pipe to the positioning arch, perform step S5 of attaching the end head stencil and hoop stencil of the guide wall; Until the guide wall reaches a predetermined strength, perform the concrete placement of the guide wall, and perform maintenance after the placement is completed in step S6, including: Determine the longitudinal gradient and elevation of the reference plane where the guide wall is located according to the distance where the guide wall is located in the tunnel, and determine the offset difference value and elevation at both ends of the orifice pipe based on the Insert angle of the pipe roof. When calculating the coordinates at both ends of the orifice pipe, Use the total station to perform surveying and positioning for the installation of the office pipe in addition to considering the Insert angle Degree should also consider the longitudinal gradient of the tunnel excavation. Based on the distance and longitudinal gradient, calculate and position the elevation of the coordinates of the orifice pipe. At the distance where the tunnel corresponds to one end of the orifice pipe, the radius R1 of the circle where the center of one end of the orifice pipe is located = the outer contour radius of the tunnel + the height of the positioning arch + the radius of the orifice pipe. At the distance where the tunnel corresponds to the other end of the orifice pipe, Insertion angle Based on this, calculate the radius of the circle where the center of the other end of the orifice pipe is located. The radius R2 of the circle where the center of the other end of the orifice pipe is located = R1 + the Insert angle DegreeIt is the displacement distance of the other end of the orifice pipe, by which the elevations at both ends of the orifice pipe are obtained, and the offset of the orifice pipe is obtained based on the quantity and spacing of each orifice pipe, and the elevations and positions at both ends of the orifice pipe are corrected based on the tunnel gradient, and the specific position of the orifice pipe is obtained through software modeling, There are two positioning arches. The outer diameters of the two positioning arches are determined based on the orifice pipe diameter, the spacing between the two positioning arches, and the tunnel radius. The arch connection method uses bolt joining of connection plates to form a full ring so as not to interfere with the positioning of some orifice pipes, and the connection plates do not leak from the outer contour of the arch. Combine the drawings, of the positioning arch Driving of surveying piles After accurate positioning and welding reinforcement, install the orifice pipe. On the support arch Drawing development Based on this, draw the distribution position of one end of the orifice pipe. On the installed support arch, draw the distribution positions of the end heads of 50 orifice pipes evenly based on the pre-calculated arc length. On the positioning arch close to the palm surface, a plurality of radial steel bars along its radial direction are welded. The length of the radial steel bars conforms to the radial thickness of the guide wall. Use the total station for positioning. On the radial steel bars, define an arc corresponding to the location where the center of the other end of the orifice pipe is located. Use the support steel bars to extend in an arc along the location where the orifice pipe is located to support the other end of the orifice pipe. After the orifice pipe is installed at the corresponding position, it is fixed by welding. Install the orifice pipe one by one, bend and connect the upper part of the radial steel bars with steel bars, and it is used to support the hoop stencil. Construction method of large pipe roof guide wall in shallow-buried tunnel opening. Beneficial effects

[0007] Determine the out - sert angle of the orifice pipe of the pipe - roof guide wall, use the out - sert angle of the guide tube to position the pipe - roof, avoid entering the correct hole and excavating the contour line during the excavation construction, ensure accurate angle calculation, convenient construction, ensure the reinforcement effect of the large pipe - roof, realize the safe entry of the tunnel into the opening, and obtain relatively good economic and social benefits.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0009] Before construction, understand the tunnel design drawings and prepare the construction technology description. As shown in FIGS. 1 - 3, it is a construction method of the large pipe - roof guide wall at the shallow - buried tunnel opening, including the following steps S1 - S6. In step S1, transport construction devices such as the positioning arch 3, steel bars, tools, and orifice pipe 2 to predetermined positions, Drawing development carry out, determine the positions of the construction site, tunnel opening, and guide wall 1. In step S2, position and excavate the guide wall 1 at a preset position, and determine the deformation amount of the tunnel opening based on the properties of the surrounding rocks, Prospect , in step S3, install the inner - contour stencil and positioning arch 3 of the guide wall 1. In step S4, determine the Insert angle of the pipe - roof 4 based on the properties of the surrounding rocks, and calculate the angle of the orifice pipe 2 based on the distance of the location where the guide wall 1 is located, and the Insert angle DegreeUse [equipment] to position the pipe roof 4, avoid entering the correct hole and excavating the contour line during the excavation construction, with accurate angle calculation, convenient construction. In step S5, after installing and adjusting each orifice pipe 2 on the positioning arch 3, install the end head stencil and hoop stencil of the guide wall 1. In step S6, pour the concrete of the guide wall 1 until it reaches the specified strength, and perform maintenance after the pouring is completed. In one embodiment, the length of the soil tunnel pipe roof 4 is 20 - 30 m, Insert angle Degree is 2° - 3°, or the length of the pipe roof 4 is 30 - 50 m, Insert angle Degree is 3° - 5°, and the pipe roof 4 is installed using an air-down-the-hole hammer. The length of the rock tunnel long pipe roof 4 is 10 - 20 m, Insert angle Degree is 1° - 2°, and the pipe roof 4 is installed using a guide bit.

[0010] In another selectable embodiment, the drilling path of the pipe roof 4 is often not a straight line along the direction of the orifice pipe 2 due to the influence of the geological hardness. In the case of loose soil layers and soft surrounding rocks, the drilling path of the large pipe roof 4 is similar to a parabola, and the longer the pipe roof 4, the more obvious the drooping at the tail end. In hard surrounding rocks, the drilling path of the large pipe roof 4 may shift upward. In step S4, combine the drawings, and determine the longitudinal gradient and elevation of the reference plane where the guide wall 1 is located according to the distance where the guide wall 1 is located in the tunnel, and determine the offset difference value and elevation at both ends of the orifice pipe 2 based on the Insert angle of the pipe roof 4, and Use the total station to perform surveying and positioning for the installation of the office pipe when calculating the coordinates at both ends of the orifice pipe 2, InsertIn addition to considering the angle, the longitudinal gradient of the tunnel excavation should also be considered. Based on the distance and the longitudinal gradient, it is used to calculate and position the elevation of the coordinates of the orifice pipe 2. Taking the example that the pipe roof 4 at the location of the tunnel exit corresponds to the orifice pipe 2, at the distance where the tunnel corresponds to one end of the orifice pipe 2, the radius R1 of the circle where the center of one end of the orifice pipe 2 is located = the outer contour radius of the tunnel + the height of the positioning arch 3 + the radius of the orifice pipe 2. At the distance where the tunnel corresponds to the other end of the orifice pipe 2, Insertion angle Based on this, calculate the radius of the circle where the center of the other end of the orifice pipe 2 is located, and the radius R2 of the circle where the center of the other end of the orifice pipe 2 is located = R1 + the displacement distance of the other end of the orifice pipe 2 at this Insert angle Degree Thus, obtain the elevations of both ends of the orifice pipe 2, and based on the quantity and spacing of each orifice pipe 2, obtain the offset of the orifice pipe 2. In addition, the tunnel gradient should also be considered. Based on the tunnel gradient, correct the elevations and positions of both ends of the orifice pipe 2, and obtain the specific position of the orifice pipe 2 through software modeling simulation.

[0011] In another alternative embodiment, in step S3, there are two positioning arches 3, and the outer diameters of the two positioning arches 3 are determined based on the diameter of the orifice pipe 2, the spacing between the two positioning arches 3, and the tunnel radius. The arch connection method uses bolt joining of the connecting plate to form a full ring so as not to interfere with the positioning of some orifice pipes 2, and the connecting plate does not leak from the outer contour of the arch. Generally, two front and rear positioning arches 3 are set to facilitate the positioning of the orifice pipe 2. The bending radius of the positioning arch 3 can be estimated from the diameter of the orifice pipe 2 used on site and the design drawing size. When processing the positioning arch 3, considering the convenience of installation, it should be evenly divided into 3 sections or 5 sections with an asymmetric length, and the connection joint should be avoided from being installed on the positive dome of the guide wall 1.

[0012] In another alternative embodiment, after combining the drawings, measuring the loft, accurately positioning, and welding and reinforcing the positioning arch 3, the orifice tube 2 is installed. For the support arch, the distribution position of one end of the orifice tube 2 is drawn based on the drawing loft. For the installed support arch, the distribution positions of the end heads of 50 orifice tubes 2 are evenly drawn based on the pre-calculated arc length. A plurality of radial reinforcing bars along its radial direction are welded to the positioning arch 3 close to the palm surface. The length of the radial reinforcing bar is adapted to the radial thickness of the guide wall 1, which is about 70 cm in this application. The total station determines the location where the orifice tube 2 is positioned on the positioning arch 3. Specifically, it is positioned using the total station. For the radial reinforcing bar, an arc corresponding to the location where the center of the other end of the orifice tube 2 is located is defined. The support reinforcing bar extends in an arc along the location where the orifice tube 2 is positioned. Specifically, a Φ25 reinforcing bar is bent along this arc to support the other end of the orifice tube 2. After the orifice tube 2 is installed at the corresponding position, it is fixed by welding. The orifice tubes 2 are installed one by one, and the upper part of the radial reinforcing bar is bent and connected with a Φ25 reinforcing bar, which is used to support the hoop stencil and effectively prevent cracks in the guide wall 1 after the dark holes are dug.

[0013] In another alternative embodiment, in step S2, when the rock around the surrounding rock opening is a plastic soil layer, Expected The deformation amount is 40 cm to 60 cm (40 cm, 50 cm, or 60 cm according to the actual construction requirements Estimate ), and when the rock around the surrounding rock opening is slope soil, loose soil, or soft soil, Expected The deformation amount is 30 cm to 40 cm (40 cm, 35 cm, or 30 cm according to the actual construction requirements Estimate ), and when the rock around the surrounding rock opening is soft rock or fractured rock mass, Expected The deformation amount is 20 cm to 30 cm (20 cm, 25 cm, or 30 cm according to the actual construction requirements Estimate ), and when the rock around the surrounding rock opening is medium-soft rock or jointed rock mass, ExpectedThe deformation amount is 10 cm to 20 cm (10 cm, 15 cm or 20 cm according to the actual construction requirements), and by selecting the reserved amount for different surrounding rock properties, it is avoided that the guide wall 1 in the construction process settles under the influence of soil quality. Estimate ) and by selecting the reserved amount for different surrounding rock properties, it is avoided that the guide wall 1 in the construction process settles under the influence of soil quality.

[0014] In another alternative embodiment, before the construction of the guide wall 1, it is necessary to detect the ground bearing force, ensure that the bearing force is 150 KPa or more, the guide wall 1 is placed in place using C20 concrete, the thickness of the guide wall 1 is 1 m, the concrete is placed in a left-right symmetric manner, and the height difference between the left and right is 1 m or less. In order to improve the guiding accuracy of the orifice tube 2, the longitudinal length of the guide wall 1 is 200 cm.

[0015] In another alternative embodiment, based on the properties of the rock around the tunnel, the structure of the inner contour template of the guide wall 1 is determined, and the inner contour template of the guide wall 1 is supported by a clay mold, a core clay steel mold or a holder steel mold.

[0016] In this embodiment, when the tunnel surrounding rock is a soft soil layer, using a clay mold to support the inner contour stencil of the guide wall 1 means that while excavating the operation platform of the pipe roof 4, the side slope is excavated and reinforced at the same time, and the shape of the clay mold is modified to the design dimensions using an excavator. The longitudinal length of the clay mold is greater than the longitudinal length of the guide wall 1. The part outside the range of the guide wall 1 is slightly higher than the design dimensions, which simplifies the reinforcement of the end head stencil and can prevent grout leakage. The excavator can only roughly repair the clay mold. If the clay mold contour is controlled and is about 50 cm short of the design contour, it needs to be changed to manual excavation, otherwise it is easy to over-excavate and the clay mold shape becomes irregular. Until it meets the requirements, the clay mold is repeatedly measured and manually modified based on the measurement results to continue the modification of the clay mold. Mortar is applied to the surface of the clay mold to improve its flatness, and plywood, color bar cloth or waterproof board is laid, which is easy to demold after digging a dark hole. After installing the positioning arch 3 and adjusting the position of the orifice pipe 2, the end head stencil and the hoop stencil are fixed and installed to pour the concrete of the guide wall 1. This includes determining the distance, a certain height horizontal line and the tunnel center line for the measurement loft, and drawing lines based on the five inch station method to reduce the number of measurement lofts and improve the construction efficiency of the clay mold modification. When laying plywood, it should be laid from both sides to the middle to ensure the correct stacking method up and down, and prevent the plywood from being rolled up by the brushing action during the concrete pouring process. When installing the inner steel arch of the guide wall 1, it is desirable to support the concrete mat block at the lower part of the arch to prevent "exposure". An appropriate amount of anchor rods should be applied and fixed to the arch closer to the palm surface, and Φ22 threaded steel is used as the connecting rib between two adjacent rings of steel arches and welded firmly.

[0017] In this embodiment, when the rock around the tunnel is a stable non-weathered rock stratum, supporting the inner contour stencil of the guide wall 1 using a core clay steel mold involves the following steps: After excavating the construction platform for the pipe roof 4, perform partial excavation of the lower slip of the guide wall 1 and reserve the core clay inside the guide wall 1; ensure that the excavation outer edge of the lower slip of the guide wall 1 does not penetrate into the guide wall 1 to create a construction space; conduct measurement and setting out to determine the position of the core clay steel mold, and install the core clay steel mold to support the inner contour stencil of the guide wall 1; use scaffolding, steel pipes, and brackets to provide multi-point short support for the core clay steel mold; after installing the positioning arch 3 to adjust the position of the orifice pipe 2, fix and install the end head stencil and hoop stencil to place the concrete of the guide wall 1. During the positioning of the arch, perform measurement to ensure that one ring of the arch is kept in the same distance cross-section as much as possible, guarantee that each ring of the arch is positioned at a predetermined position, apply a release agent to the steel template before placing the concrete for convenient subsequent demolding. To reduce the marks of the template slots, lay an additional waterproof board on the template to make the concrete surface smoother.

[0018] In this embodiment, when the rock around the tunnel is an unstable weathered rock stratum, supporting the inner contour stencil of the guide wall 1 using a holder steel mold includes the following steps: after excavating the construction platform of the pipe roof 4, excavating a part of the lower slip of the guide wall 1; constructing a scaffold used to support the inner contour stencil of the guide wall 1, installing and positioning the holder steel mold, laying the inner contour stencil of the guide wall 1 on the inner layer of the holder steel mold; installing the positioning arch 3 to adjust the position of the orifice pipe 2, and then fixing and installing the end head stencil and the hoop stencil to place the concrete of the guide wall 1. During the positioning of the arch, measurements are taken to ensure that each ring of the arch is held in the same distance cross-section as much as possible, guaranteeing that each ring of the arch is positioned at a predetermined position. Whether it is an arch for supporting the inner contour stencil or an arch for supporting the orifice pipe 2, high requirements are imposed on their processing dimensions. After the processing is completed in the processing factory, assembly trial production is carried out, and after meeting the requirements, it is put into the site for construction. The steel template is coated with a release agent before the concrete placement, which is convenient for subsequent demolding. In order to reduce the marks of the template slots, an additional waterproof board is laid on the template, which can make the concrete surface smoother.

[0019] In another selectable embodiment, after the guide wall 1 is constructed and solidified, the pipe roof 4 is driven in. After the pipe roof 4 is driven in, a grout stop valve 5 is attached to the pipe roof 4. The grout stop valve 5 includes a valve body 51, a grout injection pipe 52, and an exhaust pipe 53. However, the valve body 51 has an external thread and is fixed to the end of the pipe roof 4 by screw connection. The grout injection pipe 52 and the exhaust pipe 53 extend away from the guide wall 1 along the length of the valve body 51, and ball valves are distributed and correspondingly connected, thereby ensuring that the connection between the grout stop valve 5 and the pipe roof 4 is tight and does not leak by screw connection. The grout stopping effect at the end of the conventional pipe roof 4 is poor, and phenomena such as grout backflow are solved. By controlling the grout stop valve 5 with a ball valve, the pressure in the grout injection pipe 52 is effectively guaranteed, grout replenishment measures are reduced, the grout injection effect is greatly enhanced, grout injection holes and exhaust holes are installed, the exhaust hole switch is adjusted during the construction process to discharge the trapped air in the pipe, the grout injection effect is ensured, and the grout injection into the pipe roof 4 is guaranteed to be dense. The grout stop valve 5 can be recycled, the rotating sleeve is tight, the construction process is reduced, the construction cost is lowered, and the economic effect is improved.

Description of Signs

[0020] 1 Guide wall 2 Orifice tube 3 Positioning arch 4 Pipe roof 5 Grout stop valve 51 Valve body 52 Grout injection pipe 53 Exhaust pipe

Claims

1. Transporting the construction device to a predetermined position and performing drawing development in step S1; Positioning and excavating the guide wall at a preset position, and estimating the deformation amount of the tunnel opening based on the properties of the surrounding rock in step S2; Attaching two positioning arches to the guide wall in step S3; Determining the insertion angle of the pipe roof with respect to the horizontal based on the properties of the surrounding rock, and calculating the angle of the orifice pipe based on the distance of the location where the guide wall is located in the tunnel in step S4; Attaching and adjusting each orifice pipe to the positioning arch in step S5; Concreting the guide wall until it reaches a predetermined strength, and performing maintenance after the concreting is completed in step S6, including Step S4 further includes Determining the longitudinal gradient and elevation of the reference plane where the guide wall is located based on the distance of the location where the guide wall is located in the tunnel, determining the offset difference value and elevation at both ends of the orifice pipe based on the insertion angle of the pipe roof, obtaining the specific position of the orifice pipe through simulation via software modeling, and performing surveying and positioning for the installation of the orifice pipe using a total station. When calculating the elevation of the coordinates at both ends of the orifice pipe based on the insertion angle, the longitudinal distance and gradient of the tunnel excavation, When At the distance where the tunnel corresponds to one end of the orifice pipe, the radius R1 of the circle where the center of one end of the orifice pipe is located is R1 = the outer contour radius of the tunnel + the height of the positioning arch + the radius of the orifice pipe where At the distance where the tunnel corresponds to the other end of the orifice pipe, the radius R2 of the circle where the center of the other end of the orifice pipe is located is R2 = R1 + the displacement distance of the other end of the orifice pipe at the insertion angle in the radial direction of the tunnel where Obtaining the offset of the orifice pipe based on the quantity and interval of each orifice pipe, Correcting the elevation and position at both ends of the orifice pipe based on the gradient of the tunnel, The outer diameters of the two positioning arches are determined based on the diameter of the orifice pipe, the interval between the two positioning arches, and the radius of the tunnel. A construction method for a large pipe roof guide wall at a shallow-buried tunnel opening, characterized by the following.

2. In the step S2, when the rock around the surrounding rock opening is a plastic soil layer, the expected deformation amount is 40 cm to 60 cm; when the rock around the surrounding rock opening is stratified soil, loose soil, or soft soil, the expected deformation amount is 30 cm to 40 cm; when the rock around the surrounding rock opening is soft rock or fractured rock mass, the expected deformation amount is 20 cm to 30 cm; when the rock around the surrounding rock opening is medium-soft rock or jointed rock mass, the expected deformation amount is 10 cm to 20 cm, The construction method for a large pipe roof guide wall at a shallow-buried tunnel opening according to claim 1, characterized by the above.

3. Before the construction of the guide wall, detect the ground load gravity and ensure that the load gravity is 150 kPa or more. The guide wall is cast in place using C20 concrete, and the thickness of the guide wall is 1 m. The concrete is cast in a left-right symmetric manner, and the height difference between the left and right is 1 m or less. The construction method for a large pipe roof guide wall at a shallow-buried tunnel opening according to claim 1 or 2, characterized by the above.

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