Autonomous reinforcement type construction method for tunnel soft broken gushing water surrounding rock

Abstract

The invention belongs to an autonomous reinforcement type construction method for soft broken gushing water surrounding rock of a tunnel, which adopts different advanced support forms according to the hardness coefficient of tunnel rock, and adopts different advanced support forms according to the hardness coefficient (f) of the rock in front of tunneling of the tunnel of which the hardness coefficient (f) is less than or equal to 1; enhanced forepoling is adopted, specifically, grouting sealing plates, grouting steel bars and grouting anchor rods with different angles are used for sealing and gluing a tunnel top arch, the periphery of the upper portion of a side arch is tunneled into a front rock stratum, and the grouting sealing plates expand the bonding force, tensile strength and bearing capacity of original grouting anchor rods to peripheral loose rock stratums; and meanwhile, in cooperation with the excavated steel arch, the feet-lock bolts, the sprayed concrete layer and the radial grouting bolts, tunneling can safely and rapidly pass through the unfavorable geological area. The method has the advantage of being suitable for tunnel construction under poor geological conditions with frequent changes such as weakness, breaking, fracture, extrusion, weathering and serious water gushing.

Description

Technical Field

[0001] This invention relates to an autonomous reinforcement construction method for tunnels with weak, fractured, and water-bearing surrounding rock, applicable to tunnel construction under frequently changing adverse geological conditions such as weak, fractured, fractured, compressed, weathered, and severely water-bearing conditions. Background Technology

[0002] As transportation networks extend into areas with complex terrain, tunnel construction projects in areas with complex and challenging geological conditions are increasing. For example, the civil engineering construction project of the G4218 Kunsha Airport to Shiquanhe Highway is located at an average altitude of over 4500m, with a total route length of 5.8km. The Qielareba Tunnel within this section is 2935m long (single-track). The main geological type is strongly and moderately weathered andesitic tuff, characterized by fractures, broken rocks, soft rock deformation, and a disordered distribution of soft and hard rock. It features areas with both locally broken and partially intact rock, loose deposits, weathering cavities, and frequent water inrushes, creating a challenging geological environment. After tunnel excavation, the originally designed support parameters failed to meet the actual needs of the surrounding rock, and collapses could not be controlled through overall support parameters, resulting in low construction efficiency and high safety risks. For areas with fractures, broken rocks, and soft rock, the traditional support method is advanced pipe roof support. However, this method is costly, time-consuming, and labor-intensive, and still cannot guarantee the prevention of collapses after tunnel excavation in such areas.

[0003] Therefore, there is a need for an autonomous reinforcement construction method for weak, fractured, and water-bearing surrounding rock in tunnels to solve the problems raised in the existing technology. Summary of the Invention

[0004] The purpose of this invention is to provide an autonomous reinforcement construction method for weak, fractured, and water-bearing surrounding rock in tunnels, in order to solve the problems mentioned in the background art. It has the advantage of being suitable for safe and rapid tunnel construction under frequently changing adverse geological conditions such as weak, fractured, fractured, compressed, weathered, and severely water-bearing conditions.

[0005] Therefore, the present invention provides a self-reinforcing construction method for weak, fractured, water-bearing surrounding rock in tunnels, comprising the following steps: (1) Geological prediction identification: Using TSP, ground-penetrating radar and advanced horizontal drilling, the location, scale and nature of unfavorable geological bodies in front of the tunnel are predicted in advance. During the tunnel excavation process, the lithology, joints and water content of the tunnel face are closely observed and verified with the prediction results. When it is confirmed that the geological conditions in front of the tunnel have deteriorated, the range of rock hardness coefficient (f) is defined. (2) Prepare grouting sealing plates, extrusion operating heads, grouting section reinforcement bars, drilling rigs, grouting anchors, grouting and pressing equipment, grouting materials, excavators, steel arch frames, steel mesh, and shotcrete equipment; (3) Initial support dynamic enhancement technology measures: based on the severity of the geological conditions ahead of tunnel excavation; If the rock hardness coefficient (f) ≤ 1 in front of the tunnel excavation, then: (a) Enhance advance support by equipping the excavator boom with a squeezing operating head and using the squeezing operating head to hammer grouting sealing plates with a length greater than 4m into the rock strata ahead of the tunnel arch and side arch. The angle between each grouting sealing plate and the tunnel axis is 10° to 15° and the distance between each adjacent grouting sealing plate is 0.8m to 1.1m. Cement grout is injected into the surrounding rock strata through the grouting sealing plates. Between adjacent grouting sealing plates, grouting anchors with a length greater than 5m are driven into the rock strata ahead of the tunnel arch and the upper perimeter of the side arch. Each grouting anchor is inclined upward at an angle of 40° to 45° with the tunnel axis. In the lower perimeter of the side arch, grouting anchors with a length greater than 5m are driven into the rock strata ahead of the tunnel arch. Each grouting anchor is inclined upward at an angle of 40° to 45° with the tunnel axis. The spacing between grouting anchors in the lower perimeter of adjacent side arches is 1 to 1.2m. Cement grout is injected into the surrounding rock strata through each grouting anchor. After grouting is completed for 24 hours. (b) Conduct tunnel excavation for the reinforced pre-support section, with an excavation length of 4m. Steel arch frames are installed every 1.2m of excavation, with a spacing of 0.6m to 0.75m between adjacent arch frames. At the arch foot of each steel arch frame, a 3.5m to 4m long anchor pipe is installed, with a spacing of 0.5m to 0.6m between the anchor pipes on each steel arch frame. Ensure that the anchor pipes are fully grouted to effectively control the settlement of the steel arch frame. (c) Lay a steel mesh between two adjacent steel arch frames and spray concrete between the two steel arch frames in layers, with a thickness of 28-35cm. (d) Radial grouting reinforcement: After the shotcrete is completed, radial anchor grouting is carried out in the surrounding rock within a depth range of 5 to 6 m on the upper and lower perimeter walls of the tunnel top arch and side arches. The spacing between adjacent radial grouting holes is 2 to 2.5 m. This cements the loose rock mass into a whole, improves the bearing capacity and elastic modulus of the surrounding rock, and thus reduces the load acting on the support structure. (f) Repeat (a) to (d) to complete the construction of the next section of the tunnel in the weak and fractured surrounding rock; If the rock hardness coefficient in front of the tunnel is a mixture of (f)≤1 and (f)>3, then: divide and mark the boundaries of the areas where the rock hardness coefficient in front of the tunnel is (f)≤1 and (f)>3, and in the area where the rock hardness coefficient in front of the tunnel is (f)≤1, reinforce the advanced support construction according to (a); In section (f) > 3, grouting anchors with a length greater than 4 to 5 meters are drilled obliquely upward into the rock strata ahead of the tunnel arch and the upper perimeter of the side arch. The angle between each grouting anchor and the tunnel axis is 10° to 15°. The spacing between adjacent grouting anchors is 1.2 to 1.3 meters. The grouting anchors of adjacent sections extend obliquely into the rock hardness coefficient (f) ≤ 1 area by 1.5 to 2 meters. Cement grout is injected into the surrounding rock strata through the grouting anchors and grouting sealing plates. After grouting is completed for 24 hours; The tunnel excavation for the reinforced pre-support section is carried out, with an excavation length of 4m. Steel arch frames are installed every 1m of excavation, with a spacing of 0.6m to 0.75m between adjacent arch frames. At the arch foot of each steel arch frame, anchor pipes with a length of 3.5m to 4m are installed, with a spacing of 0.5m between the anchor pipes on each steel arch frame. ~0.6m, and ensure that the anchor pipe is fully grouted to effectively control the settlement of the steel arch frame. Lay a steel mesh between two adjacent steel arch frames, and spray concrete in layers between the two steel arch frames, with a thickness of 28-35cm. After the sprayed concrete is completed, radial anchor grouting is carried out on the surrounding rock within a depth range of 5-6m on the upper and lower perimeter walls of the tunnel top arch and side arches. The spacing between adjacent radial anchor grouting holes is 2-2.5m. This cements the loose rock mass and the hard rock mass into a whole, improves the self-bearing capacity and elastic modulus of the surrounding rock, thereby reducing the load acting on the support structure and completing the construction of the next section of the tunnel's weak and broken surrounding rock.

[0006] As a further description of the above technical solution: If the rock hardness coefficient (f) in front of the tunnel excavation is ≤0.6, then the enhanced advance support involves configuring a squeezing operating head on the end of the excavator's boom, and using the squeezing operating head to hammer grouting sealing plates with a length greater than 4m obliquely upward into the rock strata in front of the tunnel's top arch and side arches. The angle between each grouting sealing plate and the tunnel's centerline is 10° to 15°, and the spacing between adjacent grouting sealing plates is 0.8m to 1.1m. The grouting sealing plates are positioned at the upper end and... Every 1-1.2m, grouting sections of steel bars with a length greater than 4m, a diameter of 3-4cm, and a pointed front end are hammered into the rock strata ahead of the tunnel arch, the upper and lower arches, and the surrounding rock strata. Each grouting section of steel bar is inclined upward at an angle of 25°-30° with the tunnel axis. Cement grout is injected into the surrounding rock strata through the grouting sealing plate. The inserted grouting section of steel bars is distributed in the surrounding rock strata of the cement grout penetration zone. The grouting section of steel bars can be arranged crosswise. Between each adjacent grouting sealing plate, grouting anchors with a length greater than 5m are driven into the rock strata ahead of the tunnel arch and the upper perimeter of the side arch. The angle between each grouting anchor and the tunnel axis is 40° to 45°. In the rock strata ahead of the tunnel arch, grouting anchors with a length greater than 5m are driven into the rock strata ahead of the tunnel arch. The angle between each grouting anchor and the tunnel axis is 40° to 45°. The spacing between grouting anchors in the lower perimeter of adjacent side arches is 1 to 1.2m. Cement grout is injected into the rock strata around each grouting anchor. The rest is the same as the (a) enhanced advance support construction in the area section where (f) ≤ 1.

[0007] As a further description of the above technical solution: the deterioration of geological conditions in front of the tunnel refers to the rock hardness coefficient (f) of 70-80% of the area in front of the tunnel being ≤1.

[0008] As a further description of the above technical solution: the grouting sealing plate includes a grouting pipe, and several reinforcing bars extending obliquely to the rear outer ends of both sides are arranged at intervals around the periphery of the grouting pipe; or several reinforcing bars are arranged between two grouting pipes arranged side by side at intervals and several reinforcing bars extending obliquely to the rear outer ends of both sides are arranged at intervals on the outer sides of the two grouting pipes.

[0009] As a further description of the above technical solution: the grouting sealing plate includes a grouting pipe, and steel plates extending obliquely outward to both sides of the grouting pipe are provided around both sides, with the front end of the steel plate being a pointed bevel; or a connecting steel plate is provided between two grouting pipes arranged side by side at an interval, and steel plates extending obliquely outward to both sides are provided on the outer sides of the two grouting pipes, with the front end of the steel plate being a pointed bevel, and openings can be provided on the steel plate.

[0010] As a further description of the above technical solution: the grouting pipe in the grouting sealing plate is a grouting steel pipe with a diameter of 42-52mm, the diameter of the butt-jointed reinforcing bar is 20-25mm, the thickness of the butt-jointed steel plate is 5-10mm, and the width of the grouting sealing plate is 60-150cm.

[0011] As a further description of the above technical solution: the grout outlet hole of the grouting pipe on the grouting sealing plate is staggered from the reinforcing bar or steel plate.

[0012] As a further description of the above technical solution: the rear end of the extrusion operating head housing is provided with a connector that mates with the front operating joint of the excavator's front arm. The rear ends of both sides of the extrusion operating head housing are respectively connected to one end of the cross pillar. The other end of each cross pillar is provided with a hydraulic clamp device. The rear end of the clamp body of the hydraulic clamp device is connected to the outer end of the cross pillar. The front end of the clamp body is respectively shaft-connected to the rear ends of two hydraulic clamps. The outer side of the hydraulic clamp and the corresponding side end of the clamp body are respectively provided with docking shaft seats. A clamp hydraulic cylinder is shaft-connected between the two docking shaft seats. A hydraulic hammer is provided at the front of the extrusion operating head housing between the hydraulic clamp devices.

[0013] As a further description of the above technical solution: the sprayed concrete is C25 or C30 grade steel fiber concrete or synthetic fiber concrete.

[0014] As a further description of the above technical solution: the sprayed concrete is applied in two stages, with the thickness of the initial sprayed concrete being 14-17 cm and the thickness of the second sprayed concrete being 14-18 cm, the total spraying pressure being 0.3-0.6 MPa, and the interval between the two sprayed concrete stages being 3-4 hours.

[0015] The present invention has the following beneficial effects: 1. This invention addresses the shortcomings of tunnels where the main geological type is strongly and moderately weathered andesitic tuff, characterized by fractures, fragmentation, soft rock deformation, disordered distribution of soft and hard rocks, locally broken and partially intact rock, loose deposits, cavities, weathering troughs, water inrush, and other adverse geological conditions. In such areas, after tunnel excavation, the originally designed support parameters fail to meet the actual surrounding rock requirements, and collapses cannot be controlled through overall support parameters. This results in low construction efficiency, high costs, and significant safety risks. This invention employs different forms of pre-support based on the rock hardness coefficient of the tunnel. For tunnels with a rock hardness coefficient (f) ≤ 1, enhanced pre-support is used, including sealing the upper perimeter of the tunnel's crown and side arches with grouting plates at different angles, grouting reinforcement bars, and grouting anchors. The grouting plates increase the bonding force, tensile strength, and bearing capacity of the original grouting anchors to the surrounding loose rock layers, while reducing the amount of grouting anchors used. Simultaneously, in conjunction with post-excavation steel arch frames, anchor bolts, shotcrete layers, and radial grouting anchors, the tunnel can safely and quickly pass through areas with adverse geological conditions. The self-strengthening measures of this invention effectively ensure the safe passage of tunnels through areas with a rock hardness coefficient (f) ≤ 1. This invention has the advantage of being applicable to tunnel construction under frequently changing adverse geological conditions such as weak, broken, fractured, compressed, weathered, and severely water-bearing conditions.

[0016] 2. This invention has low operating costs, is easy to construct, requires few construction personnel, has simple procedures that are easy to master, and has good application effects. It also has the advantages of saving labor and effort, speed, high efficiency, and strong practicality. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the grouting sealing plate structure of the present invention; Figure 2 This is a schematic diagram of another embodiment of the grouting sealing plate of the present invention; Figure 3 This is a schematic diagram of the excavator structure with a compression operating head according to the present invention; Figure 4 This is a schematic diagram of the extrusion operating head structure of the present invention; Figure 5This is a schematic diagram of the tunnel excavation self-reinforcing structure of the present invention; Figure 6 for Figure 5 Schematic diagram of the cross-sectional structure of section A-A; Figure 7 This is a schematic diagram of another embodiment of the grouting sealing plate of the present invention; Figure 8 This is a schematic diagram of another embodiment of the grouting sealing plate of the present invention; Figure 9 This is a schematic diagram of the grouting reinforcement structure of the present invention; Figure 10 This is a schematic diagram of an embodiment of the self-reinforcing structure for tunnel excavation of the present invention. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. To facilitate understanding of the technical means, creative features, and achieved objectives and effects of the present invention, the present invention will be further elaborated below with reference to specific embodiments. However, the following embodiments are merely preferred embodiments of the present invention and not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments without creative effort are all within the protection scope of the present invention. Unless otherwise specified, the construction methods in the following embodiments are conventional methods. Unless otherwise specified, the materials, devices, equipment, etc., used in the following embodiments can be obtained commercially.

[0019] Example 1: As Figures 1 to 8 As shown, a self-reinforcing construction method for weak, fractured, water-bearing surrounding rock in tunnels includes the following steps: (1) Geological prediction and identification: Using TSP, ground-penetrating radar, and advanced horizontal drilling, the location, scale, and nature of unfavorable geological bodies in front of the tunnel are predicted in advance. During the tunnel excavation process, the lithology, joints, and water content of the tunnel face are closely observed and verified with the prediction results. When it is confirmed that the geological conditions in front of the tunnel have deteriorated, the range of rock hardness coefficient (f) is defined. Rock hardness coefficient (f) > 3 is medium-hard shale, relatively hard sandstone, hard granite, basalt, etc.; rock hardness coefficient (f) of 1 is soft dense clay, relatively soft bituminous coal, alluvial soil, and clayey soil; (f) of 0.8 is soft sandy clay and loess; (f) of 0.6 is humus soil, peat, soft sandy soil, and wet sand; (f) of 0.5 is sand, fine gravel, and loose soil; (f) of 0.3 is quicksand, water-bearing loess, and other water-bearing soils. Deterioration of geological conditions ahead of the tunnel refers to the rock hardness coefficient (f) being ≤1 in 70-80% of the area ahead of the tunnel.

[0020] (2) Prepare grouting sealing plates, extrusion operating heads and grouting section reinforcement bars, and prepare drilling rigs, grouting anchors, grouting and pressing equipment, grouting materials, excavators, steel arch frames, steel mesh, and shotcrete equipment.

[0021] like Figures 1 to 2 As shown, the grouting sealing plate 1 includes a grouting pipe 101, which is a grouting steel pipe with a diameter of 42-52mm and a length of 4-5m. Steel plates 102 or iron plates extending obliquely outwards from both sides of the grouting pipe 101 are provided. The thickness of the mating steel plates is 5-10mm. The width of the grouting sealing plate is 60-150cm. The grout outlet holes 103 of the grouting pipe on the grouting sealing plate are staggered from the steel plates to ensure the grouting effect. The front end of the steel plate is a pointed bevel.

[0022] Alternatively, the grouting sealing plate 1 consists of two grouting pipes arranged side by side at intervals, with a connecting steel plate between them and steel plates extending obliquely outwards from the outer sides of the two grouting pipes. The front end of the steel plate is a pointed bevel, and the rear end of the steel plate is a vertical impact end 104, used to drive the grouting sealing plate into or press it into the soft sandy soil layer by impact. The steel plate can have openings 105 to reduce the amount of steel plate used. The steel plate can be a perforated scrap steel plate or a strip of scrap steel plate of different widths. The grouting sealing plate increases the bonding force, tensile strength and bearing capacity of the original grouting anchor to the surrounding loose rock layer, and reduces the amount of grouting anchor used. The grouting sealing plate is superior to the pipe roof support function of the traditional densely arranged grouting anchor pipes.

[0023] like Figures 3 to 4 As shown, the rear end of the housing 303 of the extrusion operating head 3 is provided with a connector 301 that mates with the operating connector 207 at the front end of the excavator boom 205. The excavator 2 is a conventional excavator, consisting of a vehicle body engine 201, operating system, hydraulic system, walking mechanism and tracks 202, rear boom 203, boom, rear boom hydraulic cylinder 204, and boom hydraulic cylinder 206. The rear ends of the housing 303 of the extrusion operating head 3 are respectively connected to one end of the cross support 402. The other end of each cross support is provided with a hydraulic clamp device 4. The rear end of the clamp body of the hydraulic clamp device is connected to the outer end of the cross support. The front end of the clamp body is respectively shafted to the rear end of two hydraulic clamps 403. The outer side of the hydraulic clamp and the corresponding side end of the clamp body are respectively provided with docking shaft seats 404. The clamp hydraulic cylinder 401 is shafted between the two docking shaft seats. The front part of the housing of the extrusion operating head between the hydraulic clamp devices is provided with a hydraulic hammer 302.

[0024] In use, the extrusion operating head 3 is connected to the operating joint 207 at the front end of the excavator boom 205 via the connector 301. The excavator is operated to retract the telescopic rod of the clamp hydraulic cylinder 401, which drives the two hydraulic clamps 403 to open, placing the rear end of the grouting sealing plate between the two hydraulic clamps. The telescopic rod of the clamp hydraulic cylinder 401 extends to clamp the rear end of the grouting sealing plate. The excavator 2 is started to the tunnel face. The front and rear booms of the excavator are operated to drive the extrusion operating head and the front tip of the grouting sealing plate clamped on it to align with the upper periphery of the tunnel arch and side arch in the rock strata ahead of the excavation and insert it obliquely upward. At the same time, the hydraulic hammer 302 at the front of the extrusion operating head housing 303 is activated to hammer the rear end face of the grouting sealing plate. Under the combined action of the front and rear booms pushing forward and the hydraulic hammer, the grouting sealing plate is pressed into the rock strata ahead of the tunnel arch and side arch.

[0025] (3) Initial support dynamic enhancement technology measures: based on the severity of the geological conditions ahead of tunnel excavation; like Figures 5 to 6 As shown, if the rock hardness coefficient (f) ≤ 1 in all cases ahead of the tunnel excavation, then: (a) Enhance the advance support by equipping the excavator boom with a squeezing operating head 3. Use the squeezing operating head to hammer grouting sealing plates 1 with a length greater than 4m (maximum 5m) into the rock strata 61 in front of the tunnel arch and the upper periphery of the side arch. The angle between each grouting sealing plate and the tunnel axis is 10° to 15°. The spacing between each adjacent grouting sealing plate is 0.8m to 1.1m. Cement grout is injected into the surrounding rock strata through the grouting sealing plates at a grouting pressure of 0.5 to 1 MPa.

[0026] Between each adjacent grouting sealing plate, grouting anchors 8 with a length greater than 5m are driven into the rock strata 61 ahead of the tunnel 6 top arch and the upper perimeter of the side arch. Each grouting anchor 8 is inclined upward at an angle of 40° to 45° with the tunnel axis. In the rock strata ahead of the tunnel 6 lower perimeter of the side arch, grouting anchors with a length greater than 5m are driven into the rock strata. Each grouting anchor is inclined upward at an angle of 40° to 45° with the tunnel axis. The spacing between grouting anchors around the lower perimeter of adjacent side arches is 1 to 1.2m. Cement grout is injected into the surrounding rock strata through each grouting anchor at a grouting pressure of 0.6 to 1 MPa. After grouting is completed for 24 hours.

[0027] (b) Tunnel excavation of the reinforced pre-support section is carried out, with an excavation length of 4m. Steel arch frames 5 are installed every 1.2m of excavation. The spacing between adjacent arch frames is 0.6m to 0.75m. At the arch foot of each steel arch frame, a locking anchor pipe 7 with a length of 3.5 to 4m is installed. The spacing between the locking anchor pipes on each steel arch frame is 0.5m to 0.6m. It is ensured that the locking anchor pipes are fully grouted to effectively control the settlement of the steel arch frame. Each section of the steel arch frame can be welded into an integrated structure.

[0028] (c) A steel mesh 9 is laid between two adjacent steel arch frames 5, and concrete is sprayed in layers between the two steel arch frames. The sprayed concrete is C25 or C30 grade steel fiber concrete or synthetic fiber concrete, and the thickness of the sprayed concrete is 28-35cm. The sprayed concrete is applied in two stages. The thickness of the first sprayed concrete is 14-17cm, and the thickness of the second sprayed concrete is 14-18cm. The total spraying pressure is 0.3-0.6MPa, and the interval between the two sprayed concrete stages is 3-4 hours.

[0029] (d) Radial grouting reinforcement: After the shotcrete is completed, radial anchor bolts 81 are grouted into the surrounding rock within a depth of 5 to 6 m on the upper and lower perimeter walls of the tunnel arch and side arch. The grouting pressure is 0.7 to 1.2 MPa, and the spacing between adjacent radial grouting holes is 2 to 2.5 m. This binds the loose rock mass into a whole, improves the bearing capacity and elastic modulus of the surrounding rock, and thus reduces the load acting on the support structure.

[0030] (f) Repeat (a) to (d) to complete the construction of the next section of the tunnel in the weak and broken surrounding rock.

[0031] If the rock hardness coefficient in front of the tunnel is a mixture of (f)≤1 and (f)>3, then: divide and mark the boundaries of the areas where the rock hardness coefficient in front of the tunnel is (f)≤1 and (f)>3, and in the area where the rock hardness coefficient in front of the tunnel is (f)≤1, reinforce the advanced support construction according to (a).

[0032] In section (f) > 3, grouting anchors with a length greater than 4-5m (maximum 6m) are drilled obliquely upward into the rock strata ahead of the tunnel arch and the upper perimeter of the side arch. The angle between each grouting anchor and the tunnel axis is 10°-15°. The spacing between adjacent grouting anchors is 1.2m-1.3m. The adjacent grouting anchors extend obliquely into the rock hardness coefficient (f) ≤ 1 area for 1.5-2m. This is to use the grouting anchors in the hard rock strata and the cement grout to bind the loose rock strata. Cement grout is injected into the surrounding rock strata through the grouting anchors and grouting sealing plates. The grouting pressure of the grouting anchors in section (f) > 3 is 1-2 MPa. Grouting is carried out 24 hours after completion. The tunnel excavation for the reinforced pre-support section is carried out, with an excavation length of 4m. Steel arch frames are installed every 1m of excavation, with a spacing of 0.6m to 0.75m between adjacent arch frames. At the arch foot of each steel arch frame, a 3.5m to 4m long anchor pipe is installed, with a spacing of 0.5m to 0.6m between the anchor pipes on each steel arch frame. The anchor pipes are fully grouted to effectively control the settlement of the steel arch frame. A steel mesh is laid between two adjacent steel arch frames, and concrete is sprayed in layers between the two steel arch frames, with a sprayed concrete thickness of 28 to 35cm. After the shotcrete is completed, radial anchor grouting is performed on the surrounding rock within a depth of 5-6m on the upper and lower perimeter walls of the tunnel arch and side arches. The spacing between adjacent radial anchor grouting holes is 2-2.5m. This cements the loose rock mass and the hard rock mass into a whole, improves the bearing capacity and elastic modulus of the surrounding rock, thereby reducing the load acting on the support structure and completing the construction of the next section of the tunnel with weak and broken surrounding rock.

[0033] Example 2: As Figure 9 and Figure 10 As shown, unlike Example 1, the reinforcing bar 10 in the grouting section is a reinforcing bar with a diameter of 3-4 cm, a length greater than 4 m, and a pointed front end. If the rock hardness coefficient (f) in front of the tunnel excavation is ≤0.6, then the enhanced advance support is to equip the excavator boom with a pressing operating head, and use the pressing operating head to hammer grouting sealing plates with a length greater than 4 m obliquely upward into the rock strata in front of the tunnel arch and the upper periphery of the side arch. The angle between each grouting sealing plate and the tunnel axis is 10°-15°, and the distance between each adjacent grouting sealing plate is 0.8 m-1.1 m. At intervals of 1-1.2m, grouting section steel bars 10 with a length greater than 4m, a diameter of 3-4cm, and a pointed front end are hammered obliquely upwards into the rock strata ahead of the tunnel's top arch, side arch, and lower perimeter of the tunnel excavation. The angle between each grouting section steel bar and the tunnel axis is 25°-30°. Cement grout is injected into the surrounding rock strata through the grouting seal plate. The inserted grouting section steel bars are distributed in the surrounding rock strata of the cement grout penetration zone to improve the compressive strength and bearing capacity of the grouting section rock. The grouting section steel bars can be intersected, that is, the inserted adjacent grouting section steel bars can form intersections to improve the compressive strength and bearing capacity of the grouting section rock.

[0034] Grouting anchors longer than 5m are driven into the rock strata ahead of the tunnel's upper arch and side arches between adjacent grouting sealing plates. Each grouting anchor is angled upwards at 40°–45° to the tunnel's centerline. Similarly, grouting anchors longer than 5m are driven into the rock strata ahead of the tunnel's lower arches, also at 40°–45° to the tunnel's centerline. The spacing between adjacent grouting anchors at the lower perimeter of the side arches is 1–1.2m. Cement grout is injected into the surrounding rock strata through each anchor. This creates a bond between adjacent grouting sealing plates (angled at 10°–15° to the tunnel's centerline), grouting sections (angled at 25°–30° to the tunnel's centerline), and grouting anchors (angled at 40°–45° to the tunnel's centerline), all working together to cement and tighten the loose rock strata ahead of the tunnel's excavation. The rest is the same as in Example 1, so it will not be repeated here.

[0035] Example 3: As Figure 7 and Figure 8 As shown, the grouting sealing plate 1 includes grouting pipes 103, with several reinforcing bars 106 extending obliquely to the rear outer ends at intervals on both sides of the grouting pipes; or, between two grouting pipes arranged side by side at intervals, several reinforcing bars are provided, and along the outer sides of the two grouting pipes, several reinforcing bars extending obliquely to the rear outer ends at intervals are provided. The grouting pipes in the grouting sealing plate are grouting steel pipes with a diameter of 42-52mm, the diameter of the butt-jointed reinforcing bars is 20-25mm, and the width of the grouting sealing plate is 60-150cm. The grout outlet holes of the grouting pipes on the grouting sealing plate are staggered from the reinforcing bars. The rest is the same as in Embodiment 1, so it will not be repeated.

[0036] The following is a comparison of data between the method of this invention and the traditional method in the same area: Table 1:

[0037] Table 1 shows that all indicators of the embodiments of the present invention are superior to those of the traditional methods. The average number of collapses per 20m of tunnel construction using the present invention is 0, the average support cost per meter is reduced by 35% compared to the traditional method, the construction speed is increased by 60%, and the stability and safety are excellent. The present invention has better construction results and has the advantages of saving labor and effort during construction, simple construction, fast speed, good safety, high efficiency, and strong practicality.

[0038] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A self-reinforced construction method for tunneling in soft and broken water gushing surrounding rock, characterized in that, Comprising the following steps: (1) Geological prediction identification: using TSP, geological radar, advanced horizontal drilling, to predict the position, scale and nature of the adverse geological body in front of the tunnel, closely observe the lithology, joint, water content of the tunnel face during tunnel excavation, and verify with the prediction results, when the geological conditions in front of the tunnel are confirmed to be deteriorated, and the rock hardness coefficient (f) range is determined; (2) Prepare grouting sealing plate, extrusion operation head, grouting segment steel, prepare drilling machine, grouting anchor rod, grouting and pressure grouting equipment, grouting material, excavator, steel arch, steel mesh, shotcrete equipment; (3) Dynamic enhancement technical measures for initial support: according to the severity of the geological conditions in front of the tunnel excavation; If the rock hardness coefficient in front of the tunnel excavation is (f) ≤1, then: (a) Enhance the advanced support, configure the extrusion operation head on the front arm rod end of the excavator, use the extrusion operation head to hammer into the grouting sealing plate with a length of more than 4m in the rock layer in front of the tunnel top arch, side arch upper peripheral excavation, the angle between each grouting sealing plate and the tunnel axis is 10°-15°, the distance between each adjacent grouting sealing plate is 0.8m-1.1m, and the cement slurry is injected into the surrounding rock through the grouting sealing plate; (b) Perform tunnel excavation in the enhanced advanced support section, excavate 4m, install steel arch at every 1.2m of excavation section, the distance between adjacent arches is 0.6m-0.75m, at the foot of each steel arch, a length of 3.5-4m locking foot anchor pipe is installed, the distance between locking foot anchor pipes on each steel arch is 0.5m-0.6m, and the locking foot anchor pipe is ensured to be fully grouted to effectively control the sinking of the steel arch; (c) Steel mesh is arranged between adjacent steel arches, and concrete is sprayed between the two steel arches in layers, with a thickness of 28-35cm; (d) Radial grouting reinforcement, after the completion of the sprayed concrete, radial anchor grouting is performed in the surrounding rock within a depth range of 5-6m in the upper and lower peripheral walls of the tunnel top arch and side arch, the distance between adjacent radial grouting holes is 2-2.5m, the loose rock mass is cemented into a whole, the self-bearing capacity and elastic modulus of the surrounding rock are improved, thereby reducing the load acting on the support structure; (f) Repeat (a) to (d) to complete the construction of the next section of the tunnel soft and broken surrounding rock; If the rock hardness coefficient in front of the tunnel excavation is (f) ≤1 and (f) >3, then: divide and mark the area boundary of the rock hardness coefficient in front of the tunnel excavation, (f) ≤1, (f) >3, and perform (a) enhanced advanced support construction in the area with (f) ≤1. ​ In (f) > 3 paragraph to the tunnel top arch, side arch upper part of the periphery of the excavation of the front rock layer oblique upward into the length of more than 4 ~ 5 m of grouting anchor rod, each grouting anchor rod oblique upward with the tunnel axis angle of 10° ~ 15°, each adjacent grouting anchor rod spacing 1.2 m ~ 1.3 m, adjacent part of the grouting anchor rod oblique into the rock hard coefficient (f) ≤1 area within 1.5 ~ 2 m, through the grouting anchor rod, grouting sealing plate to its peripheral rock layer into the cement slurry, after grouting completed 24 h; The tunnel excavation of the enhanced forepoling section is carried out, and the excavation length is 4 m. The steel arch frame installation of the excavation section is carried out every 1 m of excavation. The adjacent arch frame spacing is 0.6 m ~ 0.75 m. At the arch foot of each steel arch frame, the length of the locking foot anchor pipe is 3.5 ~ 4 m. The locking foot anchor pipe spacing on each steel arch frame is 0.5 m ~ 0.6 m. The locking foot anchor pipe is ensured to be full grouting, so as to effectively control the sinking of the steel arch frame. The steel mesh is arranged between the adjacent two steel arch frames. The layered concrete is sprayed between the two steel arch frames. The sprayed concrete thickness is 28 ~ 35 cm. After the sprayed concrete is completed, the radial anchor rod grouting is carried out in the surrounding rock within the depth range of 5 ~ 6 m of the upper and lower parts of the tunnel top arch and side arch. The adjacent radial anchor rod grouting hole spacing is 2 ~ 2.5 m. The loose rock mass and the hard rock mass are cemented into an integral whole. The self bearing capacity and the elastic modulus of the surrounding rock are improved. The load acting on the supporting structure is reduced. The construction of the next section of the tunnel soft and broken surrounding rock is completed.

2. The autonomous intensification method of claim 1, wherein: If the rock hard coefficient of the front of the tunnel is (f) ≤0.6, the enhanced forepoling is configured with an extrusion operation head on the front arm rod end of the excavator. The extrusion operation head is hammered into the grouting sealing plate with a length of more than 4 m in the front rock layer of the upper periphery of the tunnel top arch and side arch. Each grouting sealing plate is obliquely upward with the tunnel axis angle of 10° ~ 15°. The spacing between each adjacent grouting sealing plate is 0.8 m ~ 1.1 m. The grouting sealing plate is hammered into the grouting section steel bar with a length of more than 4 m, a diameter of 3 ~ 4 cm and a sharp front end in the front rock layer of the upper and lower periphery of the tunnel top arch and side arch every 1 ~ 1.2 m. Each grouting section steel bar is obliquely upward with the tunnel axis angle of 25° ~ 30°. The cement slurry is injected into the peripheral rock layer through the grouting sealing plate. The inserted grouting section steel bar is distributed in the peripheral rock layer of the cement slurry permeation zone. The grouting section steel bar can be cross arranged. The grouting anchor rod with a length of more than 5 m is hammered into the front rock layer of the upper periphery of the tunnel top arch and side arch between each adjacent grouting sealing plate. Each grouting anchor rod is obliquely upward with the tunnel axis angle of 40° ~ 45°. The grouting anchor rod with a length of more than 5 m is hammered into the front rock layer of the lower periphery of the side arch. Each grouting anchor rod is obliquely upward with the tunnel axis angle of 40° ~ 45°. The adjacent lower periphery grouting anchor rod spacing of the side arch is 1 ~ 1.2 m. The cement slurry is injected into the peripheral rock layer through each grouting anchor rod. The rest of the area section with (f) ≤1 is the same as (a) enhanced forepoling construction.

3. The autonomous intensification method of claim 1, wherein: The tunnel front geological condition deterioration refers to the rock hard coefficient (f) ≤1 of 70% ~ 80% of the front of the tunnel.

4. The method of claim 1, wherein: The grouting sealing plate comprises a grouting pipe, and the periphery of the two sides of the grouting pipe is provided with a plurality of steel bars extending obliquely to the outer ends of the two sides at intervals.

5. The method of claim 1, wherein: The grouting sealing plate comprises a grouting pipe, and the periphery of the two sides of the grouting pipe is provided with a plurality of steel plates extending obliquely to the outer ends of the two sides, and the front end of the steel plate is a pointed inclined surface; or the two grouting pipes are arranged side by side at intervals, and a connecting steel plate is arranged between the two grouting pipes, and the outer sides of the two grouting pipes are provided with a plurality of steel plates extending obliquely to the outer ends of the two sides, and the front end of the steel plate is a pointed inclined surface, and the steel plate can be provided with an opening.

6. The method of claims 4 and 5, characterized by: The grouting pipe in the grouting sealing plate is a grouting steel pipe with a diameter of 42-52 mm, the butt-jointed steel bar has a diameter of 20-25 mm, the butt-jointed steel plate has a thickness of 5-10 mm, and the width of the grouting sealing plate is 60-150 cm.

7. The method of claims 4 and 5, characterized by: The grouting hole of the grouting pipe on the grouting sealing plate is arranged at intervals with the steel bar or the steel plate.

8. The method of claim 1, wherein: The rear end of the shell of the extrusion operating head is provided with a joint for butt-jointing with the operating joint at the front end of the front end arm of the excavator, the rear ends of the two sides of the shell of the extrusion operating head are connected with one end of the horizontal support respectively, the other end of each horizontal support is provided with a hydraulic clamp device, the rear end of the clamp body of the hydraulic clamp device is connected with the outer end of the connecting horizontal support, the front end of the clamp body is connected with the rear end of the two hydraulic clamp clamps respectively, the outer side of the hydraulic clamp is provided with a butt-jointing shaft seat on the corresponding side end of the clamp body, a clamp hydraulic cylinder is arranged between the two butt-jointing shaft seats, and the front part of the shell of the extrusion operating head between the hydraulic clamp devices is provided with a hydraulic air hammer.

9. The method of claim 1, wherein: The sprayed concrete is steel fiber concrete or synthetic fiber concrete of C25 or C30 grade.

10. The method of claim 1, wherein: The sprayed concrete is sprayed twice, the thickness of the primary sprayed concrete is 14-17 cm, the thickness of the secondary sprayed concrete is 14-18 cm, the total spraying pressure is 0.3-0.6 Mpa, and the interval time between the two times of spraying concrete is 3-4 h.

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