A tunnel communication channel construction method

Abstract

The present invention relates to the technical field of tunnel construction, and specifically to a method for constructing a tunnel communication channel, comprising the following steps: step S1, drilling a plurality of grouting holes divergently extending toward a second tunnel inside a first tunnel; step S2, grouting and reinforcing the portion between the first tunnel and the second tunnel through the grouting holes, injecting liquid nitrogen for cooling, so as to form a water-stop curtain corresponding to the communication channel; step S3, synchronously excavating the communication channel from the first tunnel and the second tunnel toward the middle; step S4, installing initial support steel bars by digging and supporting, and sealing the communication channel from the middle to both sides with concrete after the communication channel is connected; step S5, after the sealed concrete reaches a preset strength, removing the frozen pipe and sealing it, and grouting and reinforcing it through the frozen pipe after the water-stop curtain melts. In the case where there is no need to construct a precipitation well on the ground, there is no need to perform precipitation after grouting reinforcement, and the stability effect is good during excavation.

Description

Technical Field

[0001] The invention belongs to the technical field of tunnel construction, and in particular relates to a tunnel communication channel construction method. Background Art

[0002] With the development and application of shield construction in urban rail transit and the continuous progress and improvement of tunnel engineering technology, the role of shield construction in construction has become increasingly important and has become the mainstream construction method in urban subway construction.

[0003] At present, subway shield construction is mostly carried out in busy areas, so the connecting channel is located under the main road with busy traffic. The upper surface pipelines are dense, which affects the rotary jet reinforcement. In addition, the connecting channel is generally the lowest point of the tunnel and is buried deep. If it is located in the sand layer, the quality of rotary jet pile reinforcement is difficult to ensure. When surface dewatering is used to assist construction, it is restricted by ground conditions and the dewatering wells cannot be arranged as required. It cannot be guaranteed that the water level drops below the bottom plate, resulting in a large risk of settlement and water and sand gushing during the excavation of the connecting channel.

[0004] Therefore, it is necessary to provide an improved technical solution to address the above-mentioned deficiencies in the prior art. Summary of the invention

[0005] The purpose of the present invention is to overcome the above-mentioned deficiencies in the prior art. The present invention provides a method for constructing a tunnel communication channel.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A tunnel communication channel construction method comprises the following steps:

[0008] Step S1, measuring and setting out the connecting channel inside the first tunnel and the second tunnel, drilling a plurality of grouting holes in the first tunnel that extend divergently toward the second tunnel, and the plurality of grouting holes are evenly distributed around the connecting channel;

[0009] Step S2, grouting and reinforcing the portion between the first tunnel and the second tunnel through the grouting holes, sealing the grouting holes after the grouting is completed, drilling freezing holes on the periphery of the connecting channel, inserting freezing pipes into the freezing holes and sealing them, and injecting liquid nitrogen into the freezing pipes for cooling, so as to form a water-stop curtain corresponding to the connecting channel;

[0010] Step S3, setting up a working platform in the first tunnel and the second tunnel, cutting the inner linings of the first tunnel and the second tunnel according to the contour of the connecting channel by cutting equipment, and excavating the connecting channel synchronously from the first tunnel and the second tunnel to the middle;

[0011] Step S4, installing the initial support steel bars by digging and supporting at the same time, and sealing the connection channel with concrete from the middle to both sides after the connection channel is connected;

[0012] Step S5, after the closed concrete reaches a preset strength, the frozen pipe is removed and sealed, and grouting reinforcement is performed through the frozen pipe after the water-stop curtain melts.

[0013] Preferably, in step S3, firstly, the bell-mouth parts corresponding to the two ends of the connecting channel are fully excavated, and after the excavation, initial support is carried out by means of grid steel frames. After the initial support of the bell-mouth is completed, the main body of the connecting channel is excavated, and the initial support part is initially sprayed with concrete during the excavation process. The excavation working face is no more than two frames ahead of the grid steel frame support progress.

[0014] Preferably, in step S3, after the main body of the communication channel is excavated and the concrete is initially sprayed, a waterproof layer is laid on the inner side of the communication channel. After the waterproof layer is laid, a steel cage corresponding to the communication channel is tied, and the steel cage is provided with a trumpet structure corresponding to the two ends of the communication channel. A template is set inside the steel cage, and a pouring port and vibrating equipment corresponding to the concrete are provided on the template, and a closure is formed by pouring concrete.

[0015] Preferably, in step S3, during the steel cage tying process, a prestressed support is arranged at the bell mouth of the section communication channel, and a plurality of supporting jacks evenly distributed along the circumferential direction are arranged inside the prestressed support. During the steel bar tying process, the prestressed support is tied to the steel cage, and after the steel bar tying is completed, the supporting jacks are withdrawn for template installation.

[0016] Preferably, the prestressed support comprises a plurality of sections of spliced ​​parts connected to each other, a truss is provided on the inner side of the prestressed support, a plurality of support jacks extending radially along the communication channel are provided on the outer side of the truss, the plurality of support jacks correspond one to one with the plurality of sections of spliced ​​parts, and a pad is provided between any two adjacent sections of spliced ​​parts.

[0017] Preferably, in step S4, before concrete sealing, grouting holes extending toward the first tunnel are drilled inside the second tunnel, and a plurality of grouting holes diverge and extend toward the first tunnel, and the plurality of grouting holes are evenly distributed about the circumference of the connecting channel.

[0018] Preferably, the grouting holes drilled in the first tunnel extend to the plane corresponding to the center line of the second tunnel or the outer wall of the second tunnel;

[0019] The grouting holes drilled in the second tunnel extend to the plane corresponding to the center line of the first tunnel or the outer wall of the first tunnel.

[0020] Preferably, the freezing hole is laid out in the first tunnel by a total station, a hole is drilled on the inner side of the first tunnel segment by a hole-drilling device, and after the hole is drilled, the orifice pipe is fixed in the hole by an expansion screw, and a drill bit passes through the orifice sealing device to drill a hole.

[0021] Preferably, the orifice pipe is placed on one end of the first tunnel and is connected to a conical connecting port through a connecting flange. A conical rubber plug is provided in the connecting port. A hollow corresponding to the freezing pipe is provided in the middle of the conical rubber plug. An annular baffle is provided on the side of the conical rubber plug away from the connecting port. The baffle is connected to the connecting port by bolts to seal the freezing pipe by extrusion.

[0022] Beneficial effects: There is no need to construct a dewatering well on the ground. After grouting reinforcement, there is no need for dewatering. The excavation process has a good stability effect, is safe and reliable, and will not drain the soil under the site, ensuring the safety of the site and nearby buildings and slopes.

[0023] The first grouting reinforcement is carried out before excavation is completed to reinforce the periphery of the connecting channel. After excavation is completed, the secondary grouting reinforcement is carried out to fully release the internal stress. After the secondary grouting, the stability of the connecting channel is greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. Among them:

[0025] Figure 1 A schematic diagram of the distribution of grouting holes in a specific embodiment provided by the present invention;

[0026] Figure 2 This is a diagram of the installation structure of the orifice pipe in the specific embodiment provided by the present invention.

[0027] In the figure: 1. First tunnel; 2. Second tunnel; 3. Communication channel; 4. Bell mouth; 5. Grouting hole; 6. Freezing pipe; 7. Pipe segment; 8. Orifice pipe; 9. Expansion screw; 10. Small valve; 11. Gate valve; 12. Connection port; 13. Conical rubber plug; 14. Baffle. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention belong to the scope of protection of the present invention.

[0029] In the description of the present invention, the terms "longitudinal", "lateral", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and do not require that the present invention must be constructed and operated in a specific orientation. Therefore, they should not be understood as limitations on the present invention. The terms "connected" and "connected" used in the present invention should be understood in a broad sense. For example, they can be fixed connections or detachable connections; they can be directly connected or indirectly connected through intermediate components. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0030] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be noted that the embodiments and features in the embodiments of the present invention can be combined with each other without conflict.

[0031] like Figure 1-2 As shown, a tunnel communication channel construction method comprises the following steps: step S1, according to the actual project, determine the specific position of the communication channel 3, measure and lay out the communication channel 3 inside the first tunnel 1 and the second tunnel 2, and drill a plurality of grouting holes 5 divergently extending toward the second tunnel 2 inside the first tunnel 1, and the plurality of grouting holes 5 are evenly distributed around the communication channel 3; the circumferential diameter of the grouting holes 5 is smaller than the circumscribed circle diameter of the bell mouth 4 at both ends of the communication channel 3, and excavation is carried out after grouting is completed and initially set. During the excavation process, the grouting pipe is cut so that the grouting pipe will not be exposed inside the communication channel 3, and the communication channel 3 can be closed by lining inside the communication channel 3, so as to improve the strength of the communication channel 3.

[0032] Alternatively, in other embodiments, the grouting is carried out by a segmented withdrawal grouting method, and generally the withdrawal step distance is 0.3 m.

[0033] Step S2, grouting reinforcement is performed on the portion between the first tunnel 1 and the second tunnel 2 through the grouting hole 5. After the grouting is completed, the grouting hole 5 is blocked, and freezing holes are drilled on the outer periphery of the connecting channel 3. The circumferential diameter of the freezing hole is larger than the circumscribed circle diameter of the bell mouth 4 at both ends of the connecting channel 3, so that the frozen area will not affect the normal excavation of the connecting channel 3. The freezing pipe 6 is inserted into the freezing hole and then blocked. Before the construction of the interval connecting channel 3, the surrounding strata are reinforced by freezing method, specifically by injecting liquid nitrogen into the freezing pipe 6 for cooling to form a water-stop curtain corresponding to the connecting channel 3, so as to carry out the excavation and masonry construction of the interval connecting channel 3 in the frozen soil curtain structure to avoid groundwater leakage, and temperature measuring holes are arranged in the frozen soil curtain to correctly judge whether the frozen soil curtain is interlaced and measure the thickness of the frozen soil curtain, and pressure relief holes are arranged at both ends of the interval connecting channel 3 to reduce the influence of soil frost heave on the first tunnel 1 or the second tunnel 2. The hole can be used as an observation hole for the pressure change of the freezing curtain.

[0034] Step S3, set up a working platform at the opening of the connecting channel 3 corresponding to the first tunnel 1 and the second tunnel 2, and use cutting equipment to synchronously cut the inner lining of the first tunnel 1 and the second tunnel 2 according to the contour of the connecting channel 3, and synchronously excavate the connecting channel 3 from the first tunnel 1 and the second tunnel 2 to the middle. The operation adopts a combination of pneumatic picks, shovels and hand picks, and excavates manually. The working surface is discharged with a wheelbarrow and pushed into a special discharge box near the wellhead, and then lifted to the ground for discharge with a hoist.

[0035] Step S4, initial support reinforcement is installed by digging and supporting at the same time. The initial support reinforcement adopts grid steel frame. After each excavation of the channel part is completed, a shotcrete operation is carried out. After the connecting channel 3 is connected, concrete sealing is carried out from the middle to both sides. The concrete sealing is a permanent support, and cast-in-place reinforced concrete is used.

[0036] Step S5, after the closed concrete reaches the preset strength, stop supplying nitrogen to the freezing pipe 6, remove the freezing pipe 6 and seal the freezing hole, and after the water-stop curtain melts, grouting is performed on the freezing pipe 6 to reinforce it, so as to avoid the freezing hole from damaging the strength of the soil layer.

[0037] In an optional embodiment, in step S3, the core drilling machine is used to cut the pipe segments 8 in blocks. After the pipe segments 8 are removed, the excavation can be formally started. First, the bell mouth 4 at both ends of the communication channel 3 is excavated in full section. After the excavation, the grid steel frame is used for initial support. Before the initial support concrete is sprayed, it is necessary to hang the steel mesh. The steel mesh is processed in advance according to the requirements of the design drawings. After the excavation is completed, the mesh can be directly hung. After the mesh is hung and the grouting pipe is buried, the concrete spraying construction is carried out.

[0038] After the initial support of the bell mouth 4 is completed, the main body of the communication channel 3 is excavated. If the soil layer is relatively stable, the excavation is carried out while the support is extended to the bottom at one time; if the soil layer conditions are very poor and it is difficult to protect the side walls, short-section channel steel plate columns are used to protect the side walls in advance and extend to the bottom in sections; during the excavation process, the initial support part is sprayed with concrete, and the excavation working face is no more than two frames ahead of the grid steel frame support progress.

[0039] Since concrete is easier to dissipate heat than soil, it will affect the freezing speed of the soil layer near the pipe segment 8, thereby affecting the overall stability and water sealing of the frozen soil curtain. In particular, the thickness and strength of the frozen soil curtain at the bell mouth 4 of the section communication channel 3 and its complete bonding with the pipe segment 8 must be ensured. Two rows (four rows at the arch top) of holes are arranged at the bell mouth 4 of the construction end of the freezing hole to strengthen freezing, and freezing plates are arranged in the opposite tunnel. PE boards are used to insulate the outside of the outer two ring pipe segments 8 of the section communication channel 3 to reduce the loss of cold. Temperature measuring points are placed at the bonding point between the frozen soil wall and the pipe segment 8 to strengthen the detection of the bonding condition between the frozen soil wall and the pipe segment 8.

[0040] In an optional embodiment, after the main body of the connecting channel 3 is excavated and the concrete is initially sprayed, grouting holes 5 are drilled in the second tunnel 2, and then a waterproof layer is laid on the inner side of the connecting channel 3. Before laying the waterproof layer, the initial support must be roughly leveled. After the waterproof layer is laid, the steel cage corresponding to the connecting channel 3 is tied, and the steel cage is provided with a trumpet mouth 4 structure corresponding to the two ends of the connecting channel 3. After the construction of the steel cage is completed, a template is set on the inner side of the steel cage, and the template is provided with a corresponding concrete pouring port and vibration equipment, and a closure is formed by pouring concrete.

[0041] In an optional embodiment, during the steel cage tying process, a prestressed support is arranged at the bell mouth 4 of the section connecting channel 3. The shape of the prestressed support is matched with the inner wall of the bell mouth 4. The prestressed support is tied to the steel cage during the steel bar tying process, which can improve the stability of the stratum during construction. After the steel bar tying is completed, the supporting jack is withdrawn for template installation, and the prestressed support is poured in the concrete closing layer to ensure the structural strength.

[0042] In this embodiment, the prestressed support includes multiple sections of spliced ​​parts that are spliced ​​together, and the spliced ​​parts correspond to the supporting jacks one by one. A truss is provided on the inner side of the prestressed support. The truss is welded from I-beams or square steels and can be a proportional reduction of the cross-section of the bell mouth 4. A plurality of supporting jacks extending radially along the connecting channel 3 are provided on the outer side of the truss. One end of the supporting jack is fixed on the prestressed support, and the other end touches the spliced ​​part. A groove corresponding to the supporting jack can be provided on the spliced ​​part. A pad is provided between any two adjacent spliced ​​parts. After the jack is tightened, a pad of appropriate number or thickness is inserted between the adjacent spliced ​​parts to ensure the support stability of the prestressed support.

[0043] Furthermore, a groove corresponding to the prestressed support is provided on the inner wall of the bell mouth 4, which is reserved by the template during the initial support. A stress gauge can be set on the supporting jack, and the jacking force of each jack can be adjusted according to the measured convergent deformation at the bell mouth 4.

[0044] In an optional embodiment, before the concrete is sealed, grouting holes 5 extending toward the first tunnel 1 are drilled inside the second tunnel 2. The grouting holes 5 drilled in the second tunnel 2 are in opposite directions to the grouting holes 5 drilled in the first tunnel 1. A plurality of grouting holes 5 diverge toward the first tunnel 1. The plurality of grouting holes 5 are evenly distributed circumferentially about the connecting channel 3. In the axial projection of the connecting channel 3, the grouting holes 5 are staggered with each other. When designing the grouting holes 5 and the freezing holes, the drilling path can be optimized to avoid interference with each other.

[0045] After the excavation of the interval communication channel 3 and the communication channel 3, the original stress balance in the stratum was destroyed, causing the stress in the stratum around the channel to be redistributed. The secondary grouting support carried out in time after excavation is an important technical measure to maintain the stability of the stratum and ensure the safety of construction. The directions of the first grouting and the second grouting are opposite, thus forming a staggered support network to ensure the support effect and stability.

[0046] In this embodiment, the grouting hole 5 drilled in the first tunnel 1 extends to the plane corresponding to the center line of the second tunnel 2 or the outer wall of the second tunnel 2; the grouting hole 5 drilled in the second tunnel 2 extends to the plane corresponding to the center line of the first tunnel 1 or the outer wall of the first tunnel 1, which is specifically determined according to the actual position of the grouting hole 5.

[0047] In an optional embodiment, first of all, it is noted that the hole position should avoid the main stress-bearing reinforcement in the concrete pipe segment 8, and then a hole opener (with a diamond drill bit for coring) is used to open a hole at a designed angle, and the hole diameter is 130 mm. When the hole depth reaches 250 mm, the coring drilling is stopped, and the orifice pipe is installed. The freezing hole is laid out in the first tunnel 1 by a total station, and a hole is opened on the inner side of the pipe segment 8 by a hole opening device. After the hole is opened, the orifice pipe is fixed in the hole by an expansion screw, and the drill bit passes through the orifice sealing device to drill a hole.

[0048] The installation method of the orifice pipe is as follows: first, the orifice of the pipe segment 8 is chiseled flat, four expansion screws are installed, and then sealing rubber, raw tape, hemp or cotton thread and other sealants are wrapped around the outer wall of the orifice pipe, and the orifice pipe is hammered into the hole. The buckle plate in the middle of the orifice pipe is tightened with the expansion screw 9, the gate valve 11 is installed and opened, and a hole opener is used to pass through the ball valve for secondary hole opening. The diameter of the secondary hole is 108mm. By opening the equipment, the concrete pipe segment 8 is opened and driven to the outer wall of the second tunnel 2. When sand gushing occurs, the small valve 10 is closed in time.

[0049] In an optional embodiment, the orifice pipe is placed at one end of the tunnel and connected to a conical access port 12 through a connecting flange. A conical rubber plug 13 is provided in the access port 12. The conical rubber plug 13 is adapted to the taper of the access port 12. A central hole corresponding to the freezing pipe 6 is provided in the middle of the conical rubber plug 13. A circular baffle 14 is provided on the side of the conical rubber plug 13 away from the access port 12. The baffle 14 is connected to the access port 12 by bolts, so that the conical rubber plug 13 is inserted into the cone by extrusion. The orifice pipe is provided with a small valve 10, and the drill bit is installed in the orifice device, and a 1.5" small valve 10 is connected to the orifice device. Dry drilling is first adopted. When drilling is difficult and no progress is made, water injection drilling is carried out from the drilling rig, and the small valve 10 is opened at the same time to observe the water and sand discharge. The slurry discharge is controlled by the switch of the valve to ensure the safety of the ground and prevent settlement.

[0050] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are within the scope of protection of the pending claims of the present invention.

Claims

1. A tunnel communication channel construction method, characterized in that: The following steps are involved: Step S1, measuring and setting out the connecting channel inside the first tunnel and the second tunnel, drilling a plurality of grouting holes in the first tunnel that extend divergently toward the second tunnel, and the plurality of grouting holes are evenly distributed around the connecting channel; Step S2, grouting and reinforcing the portion between the first tunnel and the second tunnel through the grouting holes, sealing the grouting holes after the grouting is completed, drilling freezing holes on the periphery of the connecting channel, inserting freezing pipes into the freezing holes and sealing them, and injecting liquid nitrogen into the freezing pipes for cooling, so as to form a water-stop curtain corresponding to the connecting channel; Step S3, setting up a working platform in the first tunnel and the second tunnel, cutting the inner linings of the first tunnel and the second tunnel according to the contour of the connecting channel by cutting equipment, and excavating the connecting channel synchronously from the first tunnel and the second tunnel to the middle; Step S4, installing the initial support steel bars by digging and supporting at the same time, and sealing the connecting channel from the middle to both sides with concrete after the connecting channel is connected; before sealing with concrete, drilling grouting holes extending toward the first tunnel inside the second tunnel, and a plurality of grouting holes extending divergently toward the first tunnel, and the plurality of grouting holes are evenly distributed about the circumference of the connecting channel; Step S5, after the closed concrete reaches a preset strength, the frozen pipe is removed and sealed, and grouting reinforcement is performed through the frozen pipe after the water-stop curtain melts; The grouting holes drilled from the first tunnel extend to the plane corresponding to the center line of the second tunnel or the outer wall of the second tunnel; the grouting holes drilled from the second tunnel extend to the plane corresponding to the center line of the first tunnel or the outer wall of the first tunnel; In step S3, firstly, the bell-mouth parts corresponding to both ends of the communication channel are fully excavated, and after the excavation, the grid steel frame is used for initial support. After the initial support of the bell-mouth is completed, the main body of the communication channel is excavated, and the initial support part is sprayed with concrete during the excavation process. The excavation working face is no more than two frames ahead of the grid steel frame support progress; After the main body of the communication channel is excavated and the initial concrete spraying is carried out, a waterproof layer is laid on the inner side of the communication channel. After the waterproof layer is laid, the steel cage corresponding to the communication channel is tied. The steel cage is provided with a trumpet structure corresponding to both ends of the communication channel. A template is set inside the steel cage, and the template is provided with a corresponding concrete pouring port and a vibrating device, and a closure is formed by pouring concrete; In step S3, during the steel cage binding process, a prestressed support is arranged at the bell mouth of the section communication channel, and a plurality of support jacks evenly distributed along the circumferential direction are arranged inside the prestressed support. During the steel bar binding process, the prestressed support is bound into the steel cage, and after the steel bar binding is completed, the support jacks are withdrawn to install the template; The prestressed support comprises a plurality of sections of spliced ​​parts connected to each other, a truss is arranged inside the prestressed support, a plurality of support jacks extending radially along the communication channel are arranged outside the truss, the plurality of support jacks correspond one to one with the plurality of sections of spliced ​​parts, and a pad is arranged between any two adjacent sections of spliced ​​parts.

2. The tunnel communication channel construction method according to claim 1, characterized in that: The freezing holes are laid out in the first tunnel by using a total station, holes are drilled on the inner side of the pipe segments of the first tunnel by using a hole-drilling device, the orifice pipe is fixed in the hole by using an expansion screw, and the drill bit passes through the orifice sealing device to drill.

3. The tunnel communication channel construction method according to claim 2, characterized in that: The orifice pipe is placed on one end of the first tunnel and is connected to a conical access port through a connecting flange. A conical rubber plug is provided in the access port. A hollow corresponding to the freezing pipe is provided in the middle of the conical rubber plug. An annular baffle is provided on the side of the conical rubber plug away from the access port. The baffle is connected to the access port by bolts to seal the freezing pipe by extrusion.

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