A differentiated combined support method for pouring asymmetric tunnel expansion footings

Abstract

The present invention discloses a differentiated combined support method for pouring asymmetric tunnel expansion foot sockets, which mainly includes: a tunnel expansion method with one side brushing and no tunnel expansion on the other side, and a straight wall arch shape; using a pneumatic pick to manually brush and expand the tunnel according to design requirements, and temporarily retaining the original support method; cleaning the exposed head and exposed section of the anchor rod (cable) after the cross section is formed, and laying a metal mesh; after the anchor rod is installed, removing the original deformed steel shed, and spraying concrete on the tunnel surface; installing an anchor cable to connect with the erected U-shaped steel shed; installing a bottom angle anchor cable at the foot socket of the U-shaped steel shed and pouring concrete after excavation; drilling two holes in the middle of the tunnel bottom plate, and grouting after installing a grouting steel pipe; re-spraying, and continuing to advance after the stage tunnel expansion support until the overall tunnel expansion support is completed.

Description

Technical Field

[0001] The present invention relates to a differentiated combined support method for asymmetric tunnel expansion foot socket casting, which mainly realizes the surrounding rock stability after the tunnel is asymmetricly expanded through the coordinated cooperation of anchor rod (cable) active support, steel secondary passive support and foot socket casting bearing, and belongs to the field of surrounding rock stability control of deep deformed tunnels in coal mines. Background Art

[0002] The tunnel excavation process destroys the equilibrium state of the original rock stress field, causing the stress concentration and redistribution of the tunnel surrounding rock, causing the coal rock mass around the tunnel to move, deform and even destroy. When the deformation of the coal rock layer exceeds the allowable deformation of the tunnel, the tunnel cannot meet normal use. With the continuous extension of the mining level, the tunnel surrounding rock conditions become more complex, and the surrounding rock deformation is increasingly aggravated and difficult to control. The deep rock strata have complex mechanical conditions of "three highs and one disturbance", and the tunnel surrounding rock exhibits strong rheological characteristics. As a result, the deformation of the tunnel surrounding rock increases sharply after the deep well tunnel is affected by external disturbances (including mining of adjacent coal seams, fracture of roof rock strata, impact vibration caused by rock burst, etc.), which seriously hinders the normal development of underground work.

[0003] Since deep tunnels are in a high-stress environment, although active support with anchor rods (cables) is beneficial to the release of surrounding rock stress, the low strength of anchor rods (cables) makes it difficult to promote the stability of tunnel surrounding rock. The passive support of steel sections has high strength, but it has the disadvantage of being difficult to release the stress of surrounding rock. Therefore, active support with anchor rods (cables) is combined with passive support with steel sections to work together to release the stress of tunnel surrounding rock and improve the strength of surrounding rock support. In addition, steel section foot grouting is used to control the deformation of the bottom plate in view of the high stress of surrounding rock and the soft coal rock layer in deep well tunnels. At present, the method for re-expanding deformed tunnels is mainly to repeatedly brush the sidewalls on the basis of the deformed tunnels to maintain the tunnel area. The original anchor rod (cable) support needs to be cleaned, which often increases the cost. The present invention proposes a differentiated combined support method for asymmetric tunnel expansion foot pit casting. By asymmetric tunnel expansion of the deformed tunnel, the coordinated cooperation of anchor rods (cables) with U-shaped steel technology, casting at the foot pit of the steel and bottom plate grouting technology are utilized to achieve the standardization of the technical process flow of tunnel expansion and re-support of the deformed tunnel and the reduction of support cost. Summary of the invention

[0004] Traditional deformed tunnels still use the original support design after tunnel expansion, and often require repeated rework to achieve the purpose of controlling surrounding rock deformation. Construction workers do not have a standard process, and repeated anchor removal causes slow construction progress. The single support plan causes waste of support materials.

[0005] In order to solve the above problems, the present invention proposes a differentiated combined support method for pouring asymmetric tunnel expansion foot sockets, and the technical scheme adopted is: one-side brushing tunnel expansion method, the other side no longer expands the tunnel and brushes the side, and the cross-sectional shape is a straight wall arch; according to the design requirements, the pneumatic pick machine is used to manually brush the side and expand the tunnel, and the original support method is temporarily retained; after the cross-section is formed, the exposed head and exposed section of the anchor rod (cable) are cleaned and the metal mesh is laid; after the anchor rod is installed, the original deformed steel shed is removed, and the tunnel surface is initially sprayed with concrete; the anchor cable is installed to connect with the erected U-shaped steel shed; the bottom angle anchor cable is installed at the foot socket of the U-shaped steel shed and concrete is poured after excavation; two holes are drilled in the middle of the tunnel floor, and grouting is carried out after the grouting steel pipe is installed; re-spraying is carried out, and the staged tunnel expansion support is continued until the overall tunnel expansion support is completed.

[0006] The technology mainly includes the following steps:

[0007] Step 1: Investigate the surrounding rock crushing of the deformed tunnel and the tensile fracture of high-strength anchors and ordinary anchor cables. Design the tunnel expansion method to perform unilateral wall brushing on the left side of the tunnel. Design the tunnel cross-section shape to be a straight wall arch, and the cross-section size meets the requirements for underground use;

[0008] Step 2: According to the tunnel design requirements, use pneumatic picks to manually brush the deformed rock layer on the left side of the tunnel and expand the tunnel by lifting the top, and temporarily retain the original support method to ensure the safety of construction workers;

[0009] Step 3: After the cross section is formed, the exposed head of the original high-strength anchor rod on the right side is cleaned with a hydraulic shear, and the exposed section of the ordinary anchor cable on the left side and the top plate of the tunnel is cut, and a metal mesh is laid on the surface of the tunnel;

[0010] Step 4: After installing high-strength anchor bolts around the tunnel according to the differentiated support design requirements, remove the original deformed steel shed and spray concrete on the tunnel surface;

[0011] Step 5: according to the design, ordinary anchor cables are installed and connected to the erected U-shaped steel shed, and the U-shaped steel shed is fixed by sliding through the carabao cable to form a complete bearing body in the tunnel;

[0012] Step 6: Install bottom corner anchor cables at the foot of the U-shaped steel shed to control the rock formations on both sides of the bottom plate to stabilize before excavation, and pour concrete at the excavation site;

[0013] Step 7: After the tunnel floor is leveled, two floor grouting holes are drilled in the middle, and after the grouting steel pipe is installed, synchronous grouting is performed inside and outside the pipe;

[0014] Step eight, use concrete slurry for re-spraying, continue to advance after completing the stage tunnel section, and repeat several times until the overall support of the tunnel is completed.

[0015] Furthermore, in step 2, when the tunnel is expanded to the end of the high-strength anchor rod, the anchor rod is pulled out and inspected for damage, and then properly recycled and reused.

[0016] Furthermore, in step 4, the thickness of the initial spray layer is enough to cover the anchor tray.

[0017] Furthermore, in step five, a wooden backboard is used to solidify the U-shaped steel shed and the surrounding rock of the tunnel, and tie rods are used to connect the steel sheds.

[0018] Furthermore, in step six, the length, width and height of the cast body at the foot socket are 500mm, 400mm and 1000mm respectively. After the concrete cast body is formed, 200mm is exposed on the bottom plate, covering the column feet on both sides of the U-shaped steel shed.

[0019] Furthermore, in step seven, the grouting hole depth is 3000 mm.

[0020] Furthermore, in step eight, the thickness of the concrete spraying layer at the two sides and the top plate is based on covering the U-shaped steel shed, and the bottom plate position is flush with the cast body.

[0021] The advantages and beneficial effects of the present invention are as follows: the present invention performs asymmetric tunnel expansion on the deformed tunnel, omits the anchor removal process, and utilizes asymmetric support methods to give full play to the bearing capacity of the surrounding rock. The tunnel bearing body is constructed by using anchor rods (cables) and steel sections, and the bottom plate is cast at the foot pit and grouting is performed to form a unified whole to avoid bottom bulging, thereby promoting the stability of the surrounding rock after the deformation tunnel is expanded. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of a differentiated combined support method for casting an asymmetric tunnel expansion foot socket according to the present invention.

[0023] Figure 2 yes Figure 1 The expanded diagram of .

[0024] In the figure: 1 is a common anchor cable; 2 is a high-strength anchor rod; 3 is a back plate; 4 is a U-shaped steel shed; 5 is a cable clamp; 6 is the left side of the deformed tunnel; 7 is a foot pit; 8 is a cast body; 9 is a grouting hole; 10 is a bottom angle anchor cable. DETAILED DESCRIPTION

[0025] The present invention is further described in detail below with reference to the accompanying drawings and examples.

[0026] like Figure 1 As shown, a differentiated combined support method for casting asymmetric tunnel expansion foot sockets includes the following steps:

[0027] Step 1: Investigate the surrounding rock crushing of the deformed roadway and the tensile fracture of the high-strength anchor rod 2 and the ordinary anchor cable 1, design the roadway expansion method to perform unilateral brushing on the left side wall 6 of the deformed roadway, design the roadway cross-section shape to be a straight wall arch, and the cross-section size meets the requirements for underground use;

[0028] Step 2: According to the tunnel design requirements, use pneumatic picks to manually brush the deformed rock layer 6 on the left side of the deformed tunnel and expand the tunnel by picking up the top, and temporarily retain the original support method to ensure the safety of the construction workers;

[0029] Step 3: After the cross section is formed, the exposed head of the original high-strength anchor rod 2 on the right side is cleaned with a hydraulic shear, and the exposed section of the ordinary anchor cable 1 on the left side and the roof of the tunnel is cut, and a metal mesh is hung on the surface of the tunnel;

[0030] Step 4: After installing high-strength anchor bolts 2 around the tunnel according to the differentiated support design requirements, remove the original deformed steel shed and spray concrete on the tunnel surface;

[0031] Step 5: according to the design, a common anchor cable 1 is installed and connected with the erected U-shaped steel shed 4, and the U-shaped steel shed 4 is fixed by sliding through the clamp cable to form a complete bearing body of the support-surrounding rock in the tunnel;

[0032] Step 6: Install bottom corner anchor cables 10 at the foot sockets 7 of the U-shaped steel shed 4 to control the rock formations on both sides of the bottom plate to stabilize, and then excavate, and pour concrete at the excavation to form a bottom corner casting body 8;

[0033] Step 7, after the tunnel floor is leveled, two grouting holes 9 are drilled in the middle, and after the grouting steel pipe 7 is installed, synchronous grouting is performed inside and outside the pipe;

[0034] Step eight, use concrete slurry for re-spraying, and continue to advance after the stage-by-stage tunnel expansion and support until the overall tunnel expansion and support is completed.

[0035] Furthermore, in step 2, when the tunnel is expanded to the end of the high-strength anchor rod 2, the high-strength anchor rod 2 is pulled out and inspected for damage, and then recycled and reused in a reasonable manner.

[0036] Further, in step 4, the thickness of the initial spray layer is enough to cover the anchor rod 2 tray.

[0037] Furthermore, in step five, a wooden backboard 3 is used to back the U-shaped steel shed 4 and the surrounding rock of the tunnel, and the U-shaped steel sheds 4 are connected by tie rods.

[0038] Furthermore, in step six, the length, width and height of the cast body 8 at the foot recess 7 are 500 mm, 400 mm and 1000 mm respectively. After the concrete cast body 8 is formed, 200 mm is exposed on the bottom plate, covering the foot recess 7 on both sides of the U-shaped steel shed 4.

[0039] Further, in step seven, the depth of the grouting hole 9 is 3000 mm.

[0040] Furthermore, in step eight, the thickness of the concrete spraying layer at the two sides and the top plate is based on covering the U-shaped steel shed 4, and the bottom plate position is flush with the cast body 8.

[0041] In summary, the above is only the basic scheme of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A differentiated combined support method for pouring asymmetric tunnel expansion footwell, characterized in that: The steps include: Step 1: Investigate the surrounding rock crushing and asymmetric deformation and damage characteristics of the deformed roadway, and design the roadway expansion method to carry out unilateral wall brushing on the left side of the roadway. The right side is used as the new design wall and no longer expanded. The cross-sectional shape of the roadway is designed to be a straight wall arch, and the new arch foot is transferred to the deep part of the left side wall brushing; Step 2: According to the design requirements, use pneumatic picks to manually brush the deformed rock layer on the expansion side and expand the tunnel, temporarily retain the original support method, and when the tunnel is expanded to the end of the anchor rod-anchor cable, use machines to pull out the anchor rod and check the damage to ensure the safety of the construction personnel; Step 3: After the cross section is formed, the exposed head of the original anchor rod (cable) on the right side is cleaned with hydraulic shears, and the exposed section of the anchor cable on the left side and the top plate of the tunnel is cut. The brushed cross section is flat, and a metal mesh is laid on the surface of the tunnel; Step 4: After installing anchor bolts around the tunnel according to the differentiated support design requirements, remove the original deformed steel shed and spray concrete on the tunnel surface. The thickness of the initial spray layer should be enough to cover the anchor bolt tray. Step 5: According to the design, anchor cables are installed and connected to the U-shaped steel shed fixed by the cable clamps. The U-shaped steel shed and the surrounding rock of the tunnel are tightly filled with back plates, and the U-shaped steel sheds are connected with cross bars to form a complete bearing body in the tunnel; Step 6: Install bottom corner anchor cables at the foot of the U-shaped steel shed to control the rock formations on both sides of the bottom plate to stabilize before excavation. The length, width and height of the cast body at the foot are 500mm, 400mm and 1000mm respectively. After the concrete casting body is formed, 200mm is exposed on the bottom plate to cover the column feet on both sides of the U-shaped steel shed, and concrete is poured at the excavation. Step 7: After the tunnel floor is leveled, two grouting holes with a depth of 3000 mm are drilled in the middle, and after the grouting steel pipe is installed, synchronous grouting is performed inside and outside the pipe; Step eight, use concrete slurry to re-spray the supporting tunnel. The thickness of the concrete re-spraying layer should be enough to cover the U-shaped steel shed at the two sides and the top plate. The bottom plate position should be flush with the cast body. After the stage tunnel expansion support, continue to advance until the overall tunnel expansion support is completed.

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