Soil pressure balance shield three-step starting construction method for hydraulic tunnel in narrow space

Abstract

The invention relates to the technical field of tunnel shield construction, in particular to a hydraulic tunnel earth pressure balance shield three-step starting construction method in a narrow space, which comprises the following steps of: dividing an earth pressure balance shield machine and a rear support into three sections, and dividing a shield starting process into three steps; according to the method, the earth pressure balance shield tunneling machine and the matched equipment thereof are lowered in batches, the earth pressure balance shield tunneling machine launching work is safely and efficiently completed, the safety risk of the whole launching process is controllable, the construction organization is reasonable and efficient, and the problems that in-hole horizontal transportation is difficult and materials cannot follow up in time in the launching stage of the earth pressure balance shield tunneling machine in a narrow space are successfully solved; the construction period of a starting section is greatly shortened, and the construction cost is reduced. Aiming at the characteristics of narrow working well space of the hydraulic tunnel and numerous matched trolleys behind the shield tunneling machine, the device can improve the transportation efficiency of materials in the tunnel and ensure the filling of wall back grouting, and has the advantages of good technical benefit, economic benefit and progress benefit.

Description

Technical Field

[0001] The invention relates to the technical field of tunnel shield construction, and in particular to a three-step initial construction method for an earth pressure balance shield of a hydraulic tunnel in a narrow space. Background Art

[0002] With the continuous development of my country's water conservancy engineering industry, shield construction, which has a higher safety factor, less impact on ground traffic, less interference from climate change, and more efficient construction, has become an important means of constructing hydraulic tunnels in water conservancy projects. However, compared with conventional shield construction, the existing technology of hydraulic tunnel shield construction is limited by the working shaft structure of water conservancy projects. The size of most hydraulic tunnel working shafts cannot meet the overall lowering conditions of the earth pressure balance shield machine and its subsequent supporting equipment. Especially for small-diameter shield machines, the space in the tunnel is limited, and the length of the subsequent supporting trolley is more than 100m, which leads to difficulties in synchronous follow-up of segment transportation and shield pipelines, slow transportation of slag, and inability to follow up synchronous grouting in time.

[0003] In addition, in the prior art, during the construction of hydraulic tunnel shield, the shield body needs to be disassembled, excavated in sections, the reaction frame needs to be moved forward, and the trolley needs to be lowered in advance, which increases the construction process and leads to excessively high construction costs. Summary of the invention

[0004] In order to overcome the shortcomings of the prior art, the purpose of the present invention is to provide a three-step initial construction method for an earth pressure balance shield in a hydraulic tunnel in a narrow space. The process safety risk of the initial construction method is controllable, the construction organization is reasonable and efficient, and the problems of difficult horizontal transportation in the tunnel and inability to follow up materials in a timely manner during the initial stage of the earth pressure balance shield machine in a narrow space are successfully solved, thereby greatly shortening the construction period of the initial stage and reducing construction costs.

[0005] In order to achieve the purpose of the above invention, the technical solution adopted by the present invention is as follows:

[0006] The present invention provides a three-step initial construction method for an earth pressure balance shield in a hydraulic tunnel in a narrow space, comprising the following steps:

[0007] S1. Arrange the starting base: the starting base is higher than the tunnel design axis elevation;

[0008] S2. Lowering the main body of the shield: lowering the middle shield, installing the front shield, installing the segment assembly machine, lowering the tail shield, installing the screw machine, inserting the tail shield, and installing the cutterhead in turn to complete the hoisting of the main body of the shield; assembling the rear accessories on the ground and connecting them to the main body of the shield with pipelines;

[0009] S3. Installation of reaction frame: Anchor two steel plates on the bottom plate of the shield launch shaft, install reaction frame columns on the steel plates, splice and reinforce the reaction frame, and then use a crane to lift the reaction frame to the installation position of the reaction frame column. Then fix the reaction frame on the reaction frame column, and then use a planer to grind the plate surface of the reaction frame in contact with the pipe segment, and finally perform anti-floating reinforcement on the reaction frame;

[0010] S4, one-step start: The supporting trolley equipment on the ground is connected through pipelines and arranged in two rows. During the forward excavation of the shield machine, the pipeline connected to the shield machine extends forward accordingly with the excavation speed; during the shield excavation and slag removal operation, two winches are arranged at the rear of the excavation direction to transport slag and pipe segments, and a pulley is welded at the bottom of the shield tail of the shield machine. The upper and lower winches and the pulley are connected by steel strands to form a one-in and one-out traction system;

[0011] S5, two-step start: When the shield machine excavation length reaches a certain length so that the synchronous grouting is restricted, the two-step start stage is entered. During the shield construction process, when the shield machine excavates to a certain length, the negative ring segments and reaction frames are removed, the back of the negative ring segments are grouted for the second time, and the tunnel gate water stop ring is sealed. Then the first row of trolley equipment is hoisted and assembled into the tunnel to meet the needs of synchronous grouting and belt slag discharge in the tunnel; the first row of trolley equipment and the shield body in the tunnel are pushed forward synchronously until the conditions for lowering the trolley equipment after the entire row are met, and then the three-step start is carried out;

[0012] S6, three-step start: The length required for the three-step start is the overall length of the supporting trolley equipment. In this stage, all the remaining second-row trolley equipment is hoisted into the well, and then the pipelines on the ground and the well wall are removed. The second-row trolley equipment is connected with the shield main machine and the previous first-row trolley equipment to form a complete shield excavation system, completing the three-step start;

[0013] S7, normal shield tunneling stage: After the three steps are completed, the normal shield tunneling stage begins.

[0014] The three-step starting construction method of the earth pressure balance shield in a hydraulic tunnel in a narrow space of the present invention is to divide the earth pressure balance shield machine and its subsequent supporting equipment into three sections (i.e., into a shield main body, a first row of trolley equipment, and a second row of trolley equipment), and divide the shield starting process into three steps, and lower the shield machine and its subsequent supporting equipment in batches, so as to complete the starting work of the earth pressure balance shield machine safely and efficiently, and the safety risk of the whole starting process is controllable, and the construction organization is reasonable and efficient, and the problem of difficulty in horizontal transportation in the tunnel and inability to follow up materials in time during the starting stage of the earth pressure balance shield machine in a narrow space is successfully solved, and the starting period of the starting section is greatly shortened, and the construction cost is reduced. Therefore, the three-step starting construction method of the shield of the present invention can adapt to the construction site layout requirements of a small-diameter working well, and ensure the synchronous follow-up of the pipeline and the normal horizontal transportation in the tunnel.

[0015] Furthermore, in the step S1, the starting base is raised 25mm to 35mm higher than the tunnel design axis. Due to the configuration of the shield machine body, the overall center of gravity is relatively forward. In order to avoid the shield breaking through the ground wall, the shield tail is still left in the well space, and there is no restraint except the negative ring segment, which is easy to cause the phenomenon of knocking. By setting the starting base to be raised 25mm to 35mm higher than the tunnel design axis, the phenomenon of knocking can be well avoided.

[0016] Furthermore, in the step S2, before the screw machine is installed in the well, a crane is used to move the pipe segment trolley on the ground to the well, and then sleepers are laid on the pipe segment trolley. After the sleepers are laid, the screw machine is lifted horizontally onto the pipe segment trolley in the well, and then the hook is unhooked and the screw machine is transported into the well using the pipe segment trolley.

[0017] Furthermore, in the step S3, the entire plane of the steel plate is on the same horizontal plane, and the reaction frame column is installed at the center of the steel plate; a corner brace is welded at the bottom of the column to stabilize the column, and a rear support of the column is set at the same time.

[0018] Furthermore, in the step S3, the anti-floating reinforcement of the reaction frame includes drilling holes with a drilling rig, then driving threaded steel bars into the holes, and spot welding them to the reaction frame; first welding the reaction frame cross braces to the embedded steel plates on the side walls, and then welding them to the reaction frame columns after welding is completed, and adding wedge-shaped thin steel plates at locations where local welders are not in place.

[0019] Among them, since the tunnel is a circular working shaft, the circular working shaft will be restricted by the arc shape. Therefore, the arc surface force needs to be considered in the force calculation of the reaction frame to avoid uneven force. At the same time, since the circular working shaft has no top constraint, the reaction frame needs to be reinforced to prevent floating.

[0020] Among them, after the reaction frame is fixed and reinforced, it is necessary to check whether the reaction frame bolts are tightened and whether the reaction back support is stable, and then use a planer to grind the reaction frame plate surface in contact with the negative ring segment to make it smooth.

[0021] In addition, the reaction frame supports, columns and walls must be close together. If there are gaps, they must be filled with thin steel plates and then welded to avoid welding leaks.

[0022] Furthermore, in the step S4, the two rows of supporting trolley equipment on the ground are arranged, one row is arranged with eight trolleys, and the other row is arranged with nine trolleys. Among them, the pipelines of the trolley equipment at the front and rear ends of the two rows connected to each other are designed to be S-shaped to meet the pipeline connection and construction requirements.

[0023] The pipelines on the ground are laid out using I-shaped pipeline racks and fixed to the wellhead. The shaft walls need to be reinforced and fixed with I-beams to ensure the stability of the structure.

[0024] Among them, during the process of the shield machine mainframe moving forward, all pipelines connected to it, including oil lines and circuits, must be extended forward accordingly with the excavation speed. In order to achieve this process, the construction site assists the extension of the pipeline by installing tooling. The main structure of the tooling includes turnbuckle screws, I-beams, sliding trolleys and 2-meter soft slings, with a load-bearing capacity of 2 tons. The tooling ensures the smooth extension and effective support of the pipeline during the excavation process, and facilitates the shield excavation process.

[0025] Among them, the traction system drives the segment car through the pulling action of the winch, thereby realizing the discharge of slag and the transportation of segments. This arrangement effectively utilizes the traction capacity of the winch and improves the efficiency and safety of shield tunneling operations. However, due to the limitation of the extended pipeline, when the shield machine excavation length is longer, the synchronous grouting will be severely restricted. At this time, the second step starting stage is entered.

[0026] Furthermore, in the step S5, during the shield construction process, when the shield machine excavates to 50 rings, the negative ring segments and the reaction frame are removed, and the calculation formula of the friction resistance of the negative ring segments is as follows:

[0027] 1.1*F=μ×π×L×D×P

[0028] Where, μ is the friction coefficient between soil and negative ring segment, which is taken as 0.3;

[0029] D——diameter of the negative ring segment (m);

[0030] L——length of assembled tunnel (m);

[0031] P——average earth pressure acting on the back of the negative ring segment (kPa);

[0032] 1.1 – safety factor;

[0033] Among them, the calculation formula for the friction resistance of the negative ring segment is verified by taking the maximum thrust of the shield as the rated thrust of 8000kN, and the calculation is as follows:

[0034] 1.1*F=0.3×3.14×60×4.1×100=23173.2kN;

[0035] F=23173.2kN>8000kN.

[0036] The force condition for removing the negative ring segments is that the friction resistance of the assembled tunnel segments is greater than the actual thrust of the shield, and the positive ring segments can provide enough friction to meet the normal excavation requirements of the shield machine. When the shield machine excavates to 50 rings (equivalent to 60m), the length also meets the requirements of the first row of trolley equipment after lowering.

[0037] Furthermore, in the step S5, the second step needs to meet two conditions for initiation: on the one hand, the positive ring segment can provide sufficient friction to meet the normal excavation requirements of the shield machine; on the other hand, the space in the tunnel is sufficient to lower the first row of trolley equipment;

[0038] The equipment for hoisting and assembling the first row of trolleys includes a belt slag discharge system, a high-pressure control cabinet, a main control room, a synchronous grouting system, a slurry storage tank, a hydraulic system, a grease system, and a foam system, thereby meeting the needs of synchronous grouting and belt slag discharge in the tunnel.

[0039] Furthermore, in the step S5, a battery car unit is lowered into the working shaft area outside the tunnel to carry out horizontal transportation of the first row of trolley equipment. The battery car unit includes a battery car head, a slurry tank car, a muck truck and a segment truck.

[0040] Furthermore, in the step S6, a battery car unit is lowered into the working shaft area outside the tunnel to carry out horizontal transportation of the second row of trolley equipment. The battery car unit includes a battery car head, a slurry tank car, a muck truck and a segment truck.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] (1) The three-step starting construction method of the earth pressure balance shield in a hydraulic tunnel in a narrow space of the present invention is to divide the earth pressure balance shield machine and its subsequent supporting equipment into three sections (i.e., into the shield main body, the first row of trolley equipment and the second row of trolley equipment), and divide the shield starting process into three steps, and lower the shield machine and its subsequent supporting equipment in batches, so as to complete the starting work of the earth pressure balance shield machine safely and efficiently. The safety risk of the entire starting process is controllable, the construction organization is reasonable and efficient, and the problem of difficulty in horizontal transportation in the tunnel and the inability to follow up materials in time during the starting stage of the earth pressure balance shield machine in a narrow space is successfully solved, which greatly shortens the construction period of the starting section and reduces the construction cost. Therefore, the three-step starting construction method of the shield of the present invention can adapt to the construction site layout requirements of small-diameter working shafts, and ensure the synchronous follow-up of pipelines and normal horizontal transportation in the tunnel.

[0043] (2) The three-step starting construction method of the earth pressure balance shield in a narrow space of a hydraulic tunnel of the present invention can improve the material transportation efficiency in the tunnel and ensure sufficient grouting behind the wall, considering the characteristics of the narrow space of the working shaft of the hydraulic tunnel and the large number of supporting trolleys behind the shield machine.

[0044] (3) The three-step starting construction method of the earth pressure balance shield for hydraulic tunnels in a narrow space of the present invention determines the removal conditions of the negative ring segments by installing the reaction frame and reinforcing the reaction frame against floating, and calculating that the friction resistance of the negative ring segment wall is greater than the actual thrust of the shield. Then, the connecting bridge, the first row of trolley equipment and the second row of trolley equipment are lowered in batches, thereby improving the slag discharge and transportation efficiency of the shield, and having the advantages of safe and controllable construction.

[0045] (4) The three-step starting construction method of the earth pressure balance shield for hydraulic tunnels in a narrow space of the present invention is that the entire starting process is divided into three steps. During the entire starting stage, the machine needs to be shut down twice, and each time the required downtime is short. In addition, the connection between each process is reasonable and smooth, and there are few process conversions. Therefore, the construction process of the entire starting stage is continuous and efficient.

[0046] (5) The three-step starting construction method of the earth pressure balance shield for hydraulic tunnels in a narrow space of the present invention adopts mechanized construction equipment and technology. Through winches, pipeline connections, etc., manual operations are reduced and the mechanization level of construction is improved. The high degree of mechanization improves construction efficiency and quality, while also reducing the risks caused by human errors.

[0047] (6) The three-step starting construction method of the earth pressure balance shield in a hydraulic tunnel in a narrow space of the present invention has the following technical benefits: it can provide a new idea and method for the starting of shield machines in a small diameter circular working shaft, solve the problem that the complete unit and the connecting bridge of the electric cylinder truck cannot be lowered into the starting shaft, and effectively overcome the difficulty of starting shield machines in a narrow space. Compared with the traditional starting process and the starting process of the rear pilot tunnel, it has technical benefits, is more convenient and reasonable, and also has good economic benefits and progress benefits in practical applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0049] Figure 1 The invention discloses a process flow chart of a three-step initial construction method of an earth pressure balance shield for a hydraulic tunnel in a narrow space.

[0050] Figure 2 The invention discloses a layout diagram of a shield machine split start site in a three-step start construction method of an earth pressure balance shield in a hydraulic tunnel in a narrow space.

[0051] Figure 3 It is a schematic diagram of underground transportation in the initial stage of the present invention.

[0052] Figure 4 It is a schematic diagram of underground transportation in the two-step initialization stage of the present invention.

[0053] Figure 5 It is a schematic diagram of underground transportation in the three-step initialization stage of the present invention. DETAILED DESCRIPTION

[0054] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0055] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. In the present invention, the singular forms "a", "said" and "the" used in the embodiments and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0056] The following describes the invention in conjunction with specific embodiments.

[0057] Example 1

[0058] The three-step construction method of the earth pressure balance shield for hydraulic tunnels in narrow spaces is shown in the process flow chart. Figure 1 As shown, the following steps are included:

[0059] S1. Arrange the starting base: the starting base is raised higher than the tunnel design axis; in this step, the starting base can be raised by 25mm to 35mm higher than the tunnel design axis, preferably by 30mm. Due to the configuration of the shield machine body itself, the overall center of gravity is relatively forward. In order to avoid the shield breaking through the ground wall, the tail of the shield is still left in the well space, and there is no restraint except the negative ring segment, which is easy to cause the phenomenon of knocking. By setting the starting base to be 25mm to 35mm higher than the tunnel design axis, the phenomenon of knocking can be well avoided.

[0060] S2, lowering the main body of the shield into the well: lowering the middle shield into the well, installing the front shield into the well, lowering the segment assembly machine into the well, lowering the tail shield into the well, installing the spiral machine into the well, inserting the tail of the shield, and lowering the cutter head into the well to complete the hoisting of the main body of the shield; assembling the rear accessories on the ground and connecting the rear accessories to the main body of the shield with pipelines; in this step, before installing the spiral machine in the well, use a crane to move the segment trolley on the ground to the well, and then lay sleepers on the segment trolley. After the sleepers are laid, the spiral machine is hoisted horizontally onto the segment trolley in the well, and then the hook is unhooked and the spiral machine is transported in using the segment trolley.

[0061] S3. Installation of reaction frame: Anchor two steel plates on the bottom plate of the shield launch shaft, install reaction frame columns on the steel plates, splice and reinforce the reaction frame, and then use a crane to lift the reaction frame to the installation position of the reaction frame column. Then fix the reaction frame on the reaction frame column, and then use a planer to grind the plate surface of the reaction frame in contact with the pipe segment, and finally perform anti-floating reinforcement on the reaction frame;

[0062] Among them, in this step, the entire plane of the steel plate is on the same horizontal plane, and the reaction frame column is installed at the center of the steel plate; a corner brace is welded at the bottom of the column to make the column stable, and a rear support of the column is set at the same time.

[0063] In this step, the anti-floating reinforcement of the reaction frame includes drilling holes with a drilling rig, then driving threaded steel bars into the holes, and spot welding them to the reaction frame; first welding the reaction frame cross braces to the embedded steel plates on the side walls, and then welding them to the reaction frame columns after welding is completed. If the local welding machine is not in place, a thin steel plate is added with a wedge.

[0064] Among them, since the tunnel is a circular working shaft, the circular working shaft will be restricted by the arc shape. Therefore, the arc surface force needs to be considered in the force calculation of the reaction frame to avoid uneven force. At the same time, since the circular working shaft has no top constraint, the reaction frame needs to be reinforced to prevent floating.

[0065] Among them, after the reaction frame is fixed and reinforced, it is necessary to check whether the reaction frame bolts are tightened and whether the reaction back support is stable, and then use a planer to grind the reaction frame plate surface in contact with the negative ring segment to make it smooth.

[0066] In addition, the reaction frame supports, columns and walls must be close together. If there are gaps, they must be filled with thin steel plates and then welded to avoid welding leaks.

[0067] S4, one-step start: The supporting trolley equipment on the ground is connected through pipelines and arranged in two rows. During the forward excavation of the shield machine, the pipeline connected to the shield machine extends forward accordingly with the excavation speed; during the shield excavation and slag removal operation, two winches are arranged at the rear of the excavation direction to transport slag and pipe segments, and a pulley is welded at the bottom of the shield tail of the shield machine. The upper and lower winches and the pulley are connected by steel strands to form a one-in and one-out traction system;

[0068] In this step, if Figure 2 As shown, in the two rows of supporting trolley equipment on the ground, one row is arranged with eight trolleys, namely trolleys No. 1 to 8, and the other row is arranged with nine trolleys, namely trolleys No. 9 to 17. Among them, the pipelines of the trolley equipment at the front and rear ends of the two rows connected to each other are designed in an S shape, that is, Figure 2 The connecting pipelines of the No. 8 and No. 9 trolley equipment are S-shaped to meet the needs of pipeline connection and construction.

[0069] The pipelines on the ground are laid out using I-shaped pipeline racks and fixed to the wellhead. The shaft walls need to be reinforced and fixed with I-beams to ensure the stability of the structure.

[0070] Among them, during the process of the shield machine mainframe moving forward, all pipelines connected to it, including oil lines and circuits, must be extended forward accordingly with the excavation speed. In order to achieve this process, the construction site assists the extension of the pipeline by installing tooling. The main structure of the tooling includes turnbuckle screws, I-beams, sliding trolleys and 2-meter soft slings, with a load-bearing capacity of 2 tons. The tooling ensures the smooth extension and effective support of the pipeline during the excavation process, and facilitates the shield excavation process.

[0071] Among them, the traction system drives the segment car through the pulling action of the winch, thereby realizing the discharge of slag and the transportation of segments. This arrangement effectively utilizes the traction capacity of the winch and improves the efficiency and safety of shield tunneling operations. However, due to the limitation of the extended pipeline, when the shield machine excavation length is longer, the synchronous grouting will be severely restricted. At this time, the second step starting stage is entered.

[0072] Among them, the underground transportation schematic diagram of the initial stage of this step is as follows: Figure 3 shown.

[0073] S5, two-step start: When the shield machine excavation length reaches a certain length so that the synchronous grouting is restricted, the two-step start stage is entered. During the shield construction process, when the shield machine excavates to a certain length, the negative ring segments and reaction frames are removed, the back of the negative ring segments are grouted for the second time, and the tunnel gate water stop ring is sealed. Then the first row of trolley equipment is hoisted and assembled into the tunnel to meet the needs of synchronous grouting and belt slag discharge in the tunnel; the first row of trolley equipment and the shield body in the tunnel are pushed forward synchronously until the conditions for lowering the trolley equipment after the entire row are met, and then the three-step start is carried out;

[0074] In this step, during the shield construction process, when the shield machine excavates to 50 rings (in this embodiment, 50 rings are equivalent to 60 meters), the negative ring segments and reaction frames are removed, and the calculation formula of the friction resistance of the negative ring segments is as follows:

[0075] 1.1*F=μ×π×L×D×P

[0076] Where, μ is the friction coefficient between soil and negative ring segment, which is taken as 0.3;

[0077] D——diameter of the negative ring segment (m); in this embodiment, the diameter of the negative ring segment is 4.1m;

[0078] L——Length of assembled tunnel (m); in this embodiment, L is 60 meters (50 rings);

[0079] P——average soil pressure acting on the back of the negative ring segment (kPa); in this embodiment, P is 100kPa;

[0080] 1.1 – safety factor;

[0081] Among them, the calculation formula for the friction resistance of the negative ring segment is verified by taking the maximum thrust of the shield as the rated thrust of 8000kN, and the calculation is as follows:

[0082] 1.1*F=0.3×3.14×60×4.1×100=23173.2kN;

[0083] F=23173.2kN>8000kN.

[0084] The force condition for removing the negative ring segments is that the friction resistance of the assembled tunnel segments is greater than the actual thrust of the shield, and the positive ring segments can provide enough friction to meet the normal excavation requirements of the shield machine. When the shield machine excavates to 50 rings (equivalent to 60m), the length also meets the requirements of the first row of trolley equipment after lowering.

[0085] In this step, two conditions must be met for the second step to start. On the one hand, the positive ring segment can provide enough friction to meet the normal excavation requirements of the shield machine, and on the other hand, the space in the tunnel is sufficient to lower the first row of trolley equipment.

[0086] The equipment for hoisting and assembling the first row of trolleys includes a belt slag discharge system, a high-pressure control cabinet, a main control room, a synchronous grouting system, a slurry storage tank, a hydraulic system, a grease system, and a foam system, thereby meeting the needs of synchronous grouting and belt slag discharge in the tunnel.

[0087] In this step, a battery car unit is lowered into the working shaft area outside the tunnel to carry out horizontal transportation of the first row of trolley equipment. The battery car unit includes a battery car head, a slurry tank car, a muck car and a segment car.

[0088] Among them, the underground transportation schematic diagram of the second step of this step is as follows: Figure 4 shown.

[0089] S6, three-step start: The length required for the three-step start is the overall length of the supporting trolley equipment. In this stage, all the remaining second-row trolley equipment is hoisted into the well, and then the pipelines on the ground and the well wall are removed. The second-row trolley equipment is connected with the shield main machine and the previous first-row trolley equipment to form a complete shield excavation system, completing the three-step start;

[0090] In this step, a battery car unit is lowered into the working shaft area outside the tunnel to carry out horizontal transportation of the second row of trolley equipment. The battery car unit includes a battery car head, a slurry tank car, a muck truck and a segment truck.

[0091] Among them, the underground transportation schematic diagram of the three-step initial stage of this step is as follows: Figure 5 shown.

[0092] S7, normal shield tunneling stage: After the three steps are completed, the normal shield tunneling stage begins.

[0093] The three-step starting construction method of the earth pressure balance shield in the narrow space of the hydraulic tunnel of the present embodiment is to divide the earth pressure balance shield machine and its subsequent supporting equipment into three sections (i.e., into the shield main body, the first row of trolley equipment and the second row of trolley equipment), and divide the shield starting process into three steps, and lower the shield machine and its subsequent supporting equipment in batches, so as to complete the starting work of the earth pressure balance shield machine safely and efficiently, and the safety risk of the whole starting process is controllable, and the construction organization is reasonable and efficient, and successfully solves the problem of difficulty in horizontal transportation in the tunnel and the inability to follow up materials in time during the starting stage of the earth pressure balance shield machine in a narrow space, greatly shortens the construction period of the starting section, and reduces the construction cost. Therefore, the three-step starting construction method of the shield of the present invention can adapt to the construction site layout requirements of small-diameter working wells, and ensure the synchronous follow-up of pipelines and normal horizontal transportation in the tunnel.

[0094] The three-step starting construction method of the earth pressure balance shield in a hydraulic tunnel in a narrow space in the embodiment, compared with the prior art rear guide tunnel construction method, the present invention adopts a three-step starting method. In actual application, in the L3-L2 shield section of the raw water pipeline project of the Lianhuashan-Luhuakeng Water Plant section, it can avoid the 40m dark excavation of the rear guide tunnel, save about 1.54 million engineering investment, and create good economic benefits.

[0095] The three-step starting construction method of the earth pressure balance shield in a narrow space of the hydraulic tunnel in the embodiment has the following progress benefits in actual application (L3-L2 shield section of the raw water pipeline project of Lianhuashan-Luhuakeng Water Plant Section): the three-step starting process has an average work efficiency of about 3.6m / day for the first 50 rings (60m), and about 7.2m / day for the last 50 rings (60m), and a total of 25 days are required to complete the excavation work of the starting section. Compared with the traditional starting process, the three-step starting of this embodiment does not require additional engineering equipment investment, and solves the problems of difficulty in synchronous grouting of long-distance grouting pipelines, insufficient grouting volume, and inability to ensure timeliness. At the same time, the efficiency of the second-stage start-up is improved, and the construction period comparison is as follows: the length of the starting section is 120m. Since the difficulty of transporting pipelines and materials increases with distance, the average work efficiency is about 2.4m / day, and a total of 50 days are required to complete the excavation work of the starting section; in addition, the removal of the negative ring segments and the processing of the tunnel opening can be carried out at the same time. Therefore, compared with the traditional start-up process, the three-step start-up in the above practical application can complete the shield start-up work 25 days ahead of schedule.

[0096] In addition, compared with the starting process of the rear pilot tunnel, in actual application, for the 40m rear pilot tunnel, the excavation progress is about 1m / day, so the construction of the entire rear pilot tunnel takes about 40 days. For the starting excavation section, the trolley can be lowered into the well in advance, and the excavation efficiency is about 12m / day. It takes a total of 10 days to complete the excavation work of the starting section.

[0097] Therefore, the three-step start construction process adopted by the present invention has a shorter construction period than the traditional start and the post-pilot start, and has significant progress benefits.

[0098] Project Examples

[0099] The first section of the raw water pipeline project (main section) of the Lianhuashan-Luhuakeng water plant section undertaken by the company adopted the three-step starting construction method of the earth pressure balance shield in a narrow space in the shield starting process of the L3-L2 and L1-L2 shield sections. The first section of the raw water pipeline project (main section) of the Lianhuashan-Luhuakeng water plant section is located in Chang'an Town, Dongguan City, with a designed water flow of 12m 3 / s, the water supply line is arranged along Jinyu Golf Course and Lianhu Road in Chang'an Town. The total length of the section is about 4.011km, including 2 shield water supply tunnel sections with a length of about 4.0km and 3 shield working shafts.

[0100] The L3-L2 shield section was constructed using the earth pressure balance shield method. The starting mileage is LK1+801.031~LK4+011.071, the tunnel is buried at a depth of 12.1m~16.9m, and the strata it passes through are mainly fully weathered sand, residual slope soil, and plastic to hard plastic sandy clay.

[0101] The L1-L2 shield section is constructed using the earth pressure balance shield method, with a starting mileage of LK0+000~LK4+801.031 and a tunnel burial depth of 9.89m~27.46m. The strata passed through are mainly weakly to slightly weathered granite gneiss, plastic to hard plastic sandy clay, fully weathered to strongly weathered sand and soil, and local soft upper and hard lower strata.

[0102] Based on the practical application of the present invention, the shield tunneling efficiency can be improved while ensuring the safety of the shield tunneling start, and the clearance in the small-diameter circular working shaft can be maximized, ensuring the normal start-up construction of the shield tunnel in the absence of a connecting bridge and a narrow lifting area, thereby meeting the construction period requirements of the start-up section.

[0103] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A three-step initial construction method for an earth pressure balance shield in a hydraulic tunnel in a narrow space, characterized in that: The following steps are involved: S1. Arrange the starting base: the starting base is higher than the tunnel design axis elevation; S2. Lowering the main body of the shield: lowering the middle shield, installing the front shield, installing the segment assembly machine, lowering the tail shield, installing the screw machine, inserting the tail shield, and installing the cutterhead in turn to complete the hoisting of the main body of the shield; assembling the rear accessories on the ground and connecting them to the main body of the shield with pipelines; S3. Installation of reaction frame: Anchor two steel plates on the bottom plate of the shield launch shaft, install reaction frame columns on the steel plates, splice and reinforce the reaction frame, and then use a crane to lift the reaction frame to the installation position of the reaction frame column. Then fix the reaction frame on the reaction frame column, and then use a planer to grind the plate surface of the reaction frame in contact with the pipe segment, and finally perform anti-floating reinforcement on the reaction frame; S4, one-step start: The supporting trolley equipment on the ground is connected through pipelines and arranged in two rows. During the forward excavation of the shield machine, the pipeline connected to the shield machine extends forward accordingly with the excavation speed; during the shield excavation and slag removal operation, two winches are arranged at the rear of the excavation direction to transport slag and pipe segments, and a pulley is welded at the bottom of the shield tail of the shield machine. The upper and lower winches and the pulley are connected by steel strands to form a one-in and one-out traction system; S5, two-step start: When the shield machine excavation length reaches a certain length so that the synchronous grouting is restricted, the two-step start stage is entered. During the shield construction process, when the shield machine excavates to a certain length, the negative ring segments and reaction frames are removed, the back of the negative ring segments are grouted for the second time, and the tunnel gate water stop ring is sealed. Then the first row of trolley equipment is hoisted and assembled into the tunnel to meet the needs of synchronous grouting and belt slag discharge in the tunnel; the first row of trolley equipment and the shield body in the tunnel are pushed forward synchronously until the conditions for lowering the trolley equipment after the entire row are met, and then the three-step start is carried out; S6, three-step start: The length required for the three-step start is the overall length of the supporting trolley equipment. In this stage, all the remaining second-row trolley equipment is hoisted into the well, and then the pipelines on the ground and the well wall are removed. The second-row trolley equipment is connected with the shield main machine and the previous first-row trolley equipment to form a complete shield excavation system, completing the three-step start; S7, normal shield tunneling stage: After the three steps are completed, the normal shield tunneling stage begins.

2. The three-step initial construction method of an earth pressure balance shield for a hydraulic tunnel in a narrow space as claimed in claim 1, characterized in that: In the step S1, the starting base is raised by 25 mm to 35 mm higher than the elevation of the tunnel design axis.

3. The three-step initial construction method of an earth pressure balance shield for a hydraulic tunnel in a narrow space as claimed in claim 1 is characterized in that: In the step S2, before the screw machine is installed in the well, a crane is used to move the pipe segment trolley on the ground to the well, and then sleepers are laid on the pipe segment trolley. After the sleepers are laid, the screw machine is hoisted horizontally onto the pipe segment trolley in the well, and then the hook is unhooked and the screw machine is transported into the well using the pipe segment trolley.

4. The three-step initial construction method of an earth pressure balance shield for a hydraulic tunnel in a narrow space as claimed in claim 1, characterized in that: In the step S3, the entire plane of the steel plate is on the same horizontal plane, and the reaction frame column is installed at the center of the steel plate; a corner brace is welded at the bottom of the column to stabilize the column, and a rear support of the column is set at the same time.

5. The three-step initial construction method of an earth pressure balance shield for a hydraulic tunnel in a narrow space as claimed in claim 1, characterized in that: In the step S3, the anti-floating reinforcement of the reaction frame includes drilling holes with a drilling rig, then driving threaded steel bars into the holes, and spot welding them to the reaction frame; first welding the reaction frame cross braces to the embedded steel plates on the side walls, and then welding them to the reaction frame columns after welding is completed, and adding wedge-shaped thin steel plates at locations where local welders are not in place.

6. The three-step initial construction method of an earth pressure balance shield for a hydraulic tunnel in a narrow space as claimed in claim 1, characterized in that: In the step S4, two rows of supporting trolley equipment are arranged on the ground, one row is arranged with eight trolleys, and the other row is arranged with nine trolleys.

7. The three-step initial construction method of an earth pressure balance shield for a hydraulic tunnel in a narrow space as claimed in claim 1, characterized in that: In the step S5, during the shield construction process, when the shield machine excavates to 50 rings, the negative ring segments and the reaction frame are removed, and the calculation formula of the friction resistance of the negative ring segments is as follows: 1.1*F=μ×π×L×D×P Where, μ is the friction coefficient between soil and negative ring segment, which is taken as 0.3; D——diameter of the negative ring segment (m); L——length of assembled tunnel (m); P——average earth pressure acting on the back of the negative ring segment (kPa); 1.1 – safety factor; Among them, the force condition for dismantling the negative ring segments is that the friction resistance of the assembled tunnel segments is greater than the actual thrust of the shield, and the positive ring segments can provide sufficient friction to meet the normal excavation needs of the shield machine.

8. The three-step initial construction method of an earth pressure balance shield for a hydraulic tunnel in a narrow space as claimed in claim 1, characterized in that: In the step S5, the second step needs to meet two conditions to start. On the one hand, the positive ring segment can provide enough friction to meet the normal excavation requirements of the shield machine, and on the other hand, the space in the tunnel is sufficient to lower the first row of trolley equipment. The equipment for hoisting and assembling the first row of trolleys includes a belt slag discharge system, a high-pressure control cabinet, a main control room, a synchronous grouting system, a slurry storage tank, a hydraulic system, a grease system, and a foam system.

9. The three-step initial construction method of an earth pressure balance shield for a hydraulic tunnel in a narrow space as claimed in claim 1, characterized in that: In the step S5, a battery car unit is lowered into the working shaft area outside the tunnel to carry out horizontal transportation of the first row of trolley equipment. The battery car unit includes a battery car head, a slurry tank car, a muck car and a segment car.

10. The three-step initial construction method of an earth pressure balance shield for a hydraulic tunnel in a narrow space as claimed in claim 1, characterized in that: In the step S6, a battery car unit is lowered into the working shaft area outside the tunnel to carry out horizontal transportation of the second row of trolley equipment. The battery car unit includes a battery car head, a slurry tank car, a muck car and a segment car.

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