A shield tunnel decompression drainage anti-floating comprehensive management system and construction method thereof

Abstract

The invention discloses a shield tunnel decompression, drainage and anti-floating comprehensive management system and a construction method thereof. The comprehensive management system is installed during the construction period of the shield tunnel, and comprises a bag-enlarged drainage anchor rod, a drainage pump, a water storage tank and a control system; the bag-enlarged drainage anchor rod can effectively prevent the tunnel from floating up by reducing the pressure through drainage, and can also provide sufficient pull-out resistance through the enlarged bag; by adopting annular steel beams and longitudinal steel beams, the pull-out resistance reaction force provided by the bag-enlarged drainage anchor rod is evenly distributed on the pipe segment in the water storage tank area at the bottom of the shield tunnel, effectively preventing the deformation and dislocation or local damage of the pipe segment caused by uneven stress; the bag-enlarged drainage anchor rod and the water storage tank of the invention work together to reduce the pore water pressure in the soil layer at the bottom of the shield tunnel by drainage to reduce the buoyancy of the shield tunnel, and at the same time increase the water storage capacity in the water storage tank to increase the deadweight of the shield tunnel, so as to comprehensively prevent and control the floating of the shield tunnel.

Description

Technical Field

[0001] The invention relates to the technical field of anti-floating of shield tunnels, and in particular to a shield tunnel decompression and drainage anti-floating comprehensive management system and a construction method thereof. Background Art

[0002] With the rapid development of social economy and the substantial improvement of urbanization level, in order to effectively alleviate traffic pressure and explore the development potential of underground space, a large number of subway tunnels and highway tunnels constructed by shield method are increasing.

[0003] During the operation period, the shield tunnel will float to a certain extent due to the influence of the adjacent building foundation pit, pipeline gallery foundation pit and underground passage excavation, other lines crossing and the rise of groundwater level. When the floating amount of the shield tunnel exceeds the limit, it will cause cracks or misalignment between the segments, affecting the stability of driving. In serious cases, it will cause the shield tunnel bolts to break, joints to be damaged, segments to be partially broken, cracks to expand and seep water, and even cause the main structure of the tunnel to be damaged, posing a threat to the operational safety of trains or vehicles in the shield tunnel.

[0004] At present, there are relatively detailed studies on the floating mechanism and control measures of shield segments during construction, but there is still a lack of comprehensive and effective early warning and control technology for tunnel floating control during operation. Usually, the shield tunnel is rectified after floating disease occurs during operation. Generally, drainage holes are drilled on the shield segments for drainage, and then double slurry is injected for reinforcement. This method is only applicable to tunnel floating problems caused by hollowing or looseness behind the shield tunnel wall, and is not applicable to other conditions that cause tunnel floating. Other anti-floating measures for shield tunnels during operation, such as anchor rods and micro pile technology, are not widely used in shield tunnels due to the granular characteristics of the underlying soil layer of the shield tunnel and the limited pull-out resistance provided by the small cross-section of anchor rods and micro piles.

[0005] Therefore, in order to prevent and control the risk of shield tunnel uplift and the engineering hazards that may result, an effective shield tunnel decompression, drainage and anti-floating comprehensive control technology is urgently needed. Summary of the invention

[0006] In order to overcome the above-mentioned deficiencies of the prior art, the present invention provides a shield tunnel decompression, drainage and anti-floating comprehensive management system and a construction method thereof.

[0007] The technical solution adopted by the present invention to solve the technical problem is: a shield tunnel decompression drainage anti-floating comprehensive management system, including bag expansion type drainage anchor rod, drainage pump, water storage tank and control system;

[0008] The bag-enlarged drainage anchor rod is composed of an anchor rod body, a drainage channel, a grouting body, steel bars and a grouting bag; the anchor rod body is circumferentially staggered with uniformly distributed grouting holes and drainage holes; a drainage channel is arranged inside the anchor rod body, and the remaining space is arranged from the outside to the inside with a grouting body and steel bars; the drainage channel is circumferentially uniformly distributed and penetrates along the anchor rod body and is arranged inside the anchor rod body, and is tightly embedded in the grouting body, and is hydraulically connected to the groundwater in the soil layer through the drainage holes, and is not hydraulically connected to the grouting body through the sealing material; pore water pressure sensors are arranged in some of the drainage holes, and the permeable stone on the surface of the pore water pressure sensor is tightly fitted with the soil layer;

[0009] The grouting bag comprises an end grouting bag and an intermediate grouting bag; the end grouting bag is arranged at the end of the anchor body, and a plurality of intermediate grouting bags are arranged circumferentially outside the anchor body at a certain interval; the end grouting bag and the intermediate grouting bag are connected to the grouting body through the grouting hole;

[0010] The bag-enlarged drainage anchor rod is radially arranged below the water storage tank along the shield tunnel section through a waterproof layer, annular steel beams and longitudinal steel beams, and the top of the bag-enlarged drainage anchor rod is located in the water storage tank; the top of the bag-enlarged drainage anchor rod is sealed by an anchor head and a fixing bolt, a drainage through hole is left in the anchor head area where the drainage channel is located, and a grouting through hole is left in the anchor head area where the grouting body is located;

[0011] The drainage pump is located in the water storage tank and is hydraulically connected to the drainage channel through the drainage through hole and the water pipe on the anchor head;

[0012] The water storage tank is located at the bottom of the shield tunnel, and is separated from the traffic space and auxiliary equipment space in the shield tunnel by the side plates around the water storage tank and the tunnel bottom plate; a waterproof layer is laid on the bottom and sides of the water storage tank to prevent the water in the water storage tank from seeping into the soil layer and other areas of the shield tunnel; the shield tunnel is buoyed by the coordinated control of water storage in the water storage tank and drainage by the bag expansion type drainage anchor rod;

[0013] A plurality of displacement sensors are arranged on the tunnel floor and the shield tunnel;

[0014] The control system includes a signal acquisition instrument and an alarm; the control system is connected to a pore water pressure sensor, a displacement sensor and a drainage pump; the acquisition instrument can automatically read and save the pore water pressure data in the soil layer at the bottom of the shield tunnel through the pore water pressure sensor, and automatically read and save the displacement data of the shield tunnel through the displacement sensor, and the displacement data of the shield tunnel includes the buoyancy and buoyancy rate data of the tunnel; the alarm can read, warn and process the collected pore water pressure data and displacement data.

[0015] Furthermore, the anchor body is a steel pipe; the grouting bag material is a PVC film bag or other high-strength high-polymer film bag; the length, number and outer diameter of the bag-expanded drainage anchor, the diameter, spacing and number of the drainage holes, and the water flow rate of the drainage channel are determined by the drainage design flow rate; the volume of the grouting bag, the number and spacing of the intermediate grouting bags are determined by the pull-out resistance design; the number and distribution of the pore water pressure sensors and displacement sensors are determined by the monitoring design of the shield tunnel; the contact between the bag-expanded drainage anchor and the bottom pipe segment of the shield tunnel is sealed to prevent water leakage accidents.

[0016] Furthermore, a drainage board is laid in the drainage channel and is isolated from the grouting body and hydraulically disconnected by a PVC board or other high-strength high-polymer material.

[0017] Furthermore, the power of the downdraft pump is determined by the downdraft design flow rate; the downdraft pump can operate normally with or without water.

[0018] Furthermore, the volume of the water tank is determined by the drainage design requirements, the traffic space of the shield tunnel and the ancillary equipment space; the strength of the surrounding side plates and the strength of each connection of the water tank should meet the design requirements.

[0019] The present invention also provides a construction method of a shield tunnel decompression drainage anti-floating comprehensive treatment system, the method comprising the following steps:

[0020] (1) The shield tunnel's decompression, drainage and anti-floating comprehensive management system is installed in sections where there is a risk of floating due to abundant groundwater and intensive underground space development and construction activities.

[0021] (2) A water storage tank is formed at the bottom of the shield tunnel through the tunnel floor and the surrounding side plates, a waterproof layer is laid at the bottom and surrounding side of the water storage tank, and an annular steel beam and a longitudinal steel beam are installed on the waterproof layer at the bottom of the water storage tank; after drilling holes at the bottom of the water storage tank, the annular steel beam and the longitudinal steel beam according to the design requirements, the anchor body arranged with the grouting bag, the drainage channel and the pore water pressure sensor is installed in the drilled hole, the steel bar is inserted, and the anchor head with the grouting through hole and the drainage through hole is installed, and the grouting is carried out. According to the grouting pressure feedback, the grouting pressure is adjusted in real time. After the end grouting bag, the middle grouting bag and the gap in the anchor body are filled with pressurized slurry, the grouting is stopped, the fixing bolts are installed to seal, and the grouting through hole is closed to complete the installation of the bag expansion type drainage anchor.

[0022] (3) Install the drainage pump in the water tank, and connect the drainage hole on the anchor head to the drainage pump through a water pipe.

[0023] (4) Install several displacement sensors on the tunnel floor and shield tunnel; connect the control system with the pore water pressure sensor, displacement sensor and drainage pump; automatically read and save the pore water pressure sensor and displacement sensor data through the control system's data acquisition instrument, and read, warn and process the collected pore water pressure data and displacement data through the control system's alarm.

[0024] (5) Control the buoyancy of the shield tunnel through the coordinated action of the bag-expanded drainage anchor, drainage pump, water storage tank and control system;

[0025] When the excess pore water pressure in the soil layer or the buoyancy or buoyancy rate of the tunnel collected by the collector of the control system exceeds the tunnel buoyancy warning value, the alarm will sound and automatically start the drainage pump to pump water, thereby timely reducing the pore water pressure in the soil layer at the bottom of the shield tunnel to reduce the buoyancy of the shield tunnel, and at the same time increasing the water storage capacity in the water tank to increase the deadweight of the shield tunnel; based on the real-time collected excess pore water pressure or the buoyancy or buoyancy rate data of the tunnel, the operating power of the drainage pump is adjusted in real time until the risk of buoyancy of the shield tunnel is eliminated.

[0026] Furthermore, in steps (1) and (2), the water tank can be provided with partition plates at the junction of the sections according to the different drainage designs of the sections of the shield tunnel, and bag-expanded drainage anchor rods with a suitable number of drainage channels and intermediate grouting bags can be installed, and drainage pumps with matching power can be selected to form section water tanks with different drainage and anti-buoyancy capabilities along the shield tunnel.

[0027] Furthermore, in step (2), the waterproof layer is a flexible waterproof layer, which is convenient for maintenance and replacement during long-term operation; the pressure of the pressurized slurry filled in the end grouting bag, the middle grouting bag and the gap in the anchor body is determined by the pull-out resistance design, as well as the volume and strength of the bag.

[0028] Furthermore, in step (4), the control system reserves an interface for connecting to an intelligent underground space monitoring system to provide operation and maintenance monitoring data for the service life of the shield tunnel.

[0029] Furthermore, in step (5), when the excess pore water pressure in the soil layer collected by the collector of the control system conflicts with the displacement data of the tunnel, the displacement data of the tunnel shall prevail; the operating power of the drainage pump, the increased water storage capacity in the water tank and the rate of increasing the water storage capacity are determined by the design.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. The shield tunnel decompression, drainage and anti-floating comprehensive treatment system of the present invention is installed during the construction period of the shield tunnel, and is delivered and put into use at the same time as the entire shield tunnel. It can effectively avoid the current situation where floating diseases occur during the operation of the shield tunnel but the treatment time is short (the treatment of operating shield subway tunnels can only be carried out during the nighttime window when no trains are in operation, which is difficult to implement, has low efficiency and high requirements). It will effectively serve the entire life cycle of the shield tunnel operation stage.

[0032] 2. The bag-enlarged drainage anchor rod of the present invention can effectively prevent the tunnel from floating up by reducing the pressure of drainage, and can also provide sufficient pull-out resistance through the enlarged bag, further preventing the shield tunnel from floating up. Among them, the enlarged bag not only increases the contact area between the bag-enlarged drainage anchor rod and the soil layer below the shield tunnel, increasing the pull-out resistance, but also the bag is embedded in the soil after pressurized grouting, making full use of the strength of the embedded soil to provide pull-out resistance, further increasing the pull-out effect of the bag-enlarged drainage anchor rod.

[0033] 3. The present invention adopts annular steel beams and longitudinal steel beams, so that the pull-out reaction force provided by the bag-expanded drainage anchor rod is evenly distributed on the pipe segments in the water tank area at the bottom of the shield tunnel, so that the deformation is coordinated and the deformation, dislocation or local damage caused by uneven stress on the pipe segments is effectively prevented, so that the bag-expanded drainage anchor rod can safely prevent the shield tunnel from floating.

[0034] 4. The water storage tank used makes full use of the reserved space at the bottom of the shield tunnel. The water storage tank is arranged at the bottom of the tunnel and connected to the bag-expanded drainage anchor rod. It has a built-in drainage pump. The control system effectively controls the floating of the shield tunnel caused by complex hydrogeological conditions and surrounding underground excavation construction.

[0035] 5. The bag-expanded drainage anchor rod and the water storage tank in the present invention work together to reduce the pore water pressure in the soil layer at the bottom of the shield tunnel through drainage to reduce the buoyancy of the shield tunnel, while increasing the water storage capacity in the water storage tank to increase the deadweight of the shield tunnel, thereby comprehensively preventing the shield tunnel from floating up.

[0036] 6. The water storage tank of the present invention is provided with partition plates at the junctions of various tunnel sections. By adjusting the drainage channels of the bag-expanded drainage anchor rods and the number of intermediate grouting bags, as well as the power of the drainage pump, according to the different drainage designs of various sections of the shield tunnel, interval water storage tanks with different drainage capacities are formed along the shield tunnel, so as to adapt to local conditions and effectively control the buoyancy of the shield tunnel.

[0037] 7. The excess pore water pressure in the soil layer and the displacement data of the shield tunnel collected and stored in real time by the collector in the present invention can be used to analyze the pore pressure response and tunnel displacement response characteristics in the lower soil layer of the shield tunnel in the monitoring area, and to carry out scientific research on the distribution of tunnel stress field and displacement field; at the same time, combined with the real-time feedback data and effective displacement control results in the shield tunnel displacement control process, a large database of the surrounding engineering environment and floating control of the shield tunnel can be established, and a certain reference and guidance can be provided for the floating control design and construction of other shield tunnels in this area or similar areas. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a structural diagram of the shield tunnel's decompression, drainage and anti-floating comprehensive management system;

[0039] Figure 2 It is a schematic diagram of the bag expansion type drainage anchor;

[0040] Figure 3 It is the cross-section of AA;

[0041] Figure 4 It is a cross-section of BB;

[0042] In the figure, there are bag-enlarged drainage anchor 1, anchor body 1-1, grouting hole 1-1-1, anchor head 1-1-2, fixing bolt 1-1-3, drainage channel 1-2, drainage hole 1-2-1, grouting body 1-3, steel bar 1-4, end grouting bag 1-5-1, middle grouting bag 1-5-2, annular steel beam 1-6, longitudinal steel beam 1-7, drainage pump 2, water storage tank 3, waterproof layer 3-1, tunnel floor 4 and shield tunnel 5. DETAILED DESCRIPTION

[0043] The present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0044] like Figure 1-4 As shown, this embodiment provides a shield tunnel decompression drainage and anti-floating comprehensive management system, including a bag-expanded drainage anchor rod 1, a drainage pump 2, a water storage tank 3 and a control system.

[0045] The bag-enlarged drainage anchor 1 is composed of an anchor body 1-1, a drainage channel 1-2, a grouting body 1-3, a steel bar 1-4 and a grouting bag; the anchor body 1-1 is circumferentially staggered and uniformly penetrated with grouting holes 1-1-1 and drainage holes 1-2-1; the drainage channel 1-2 is arranged inside the anchor body 1-1, and the remaining space is arranged from the outside to the inside with grouting bodies 1-3. The drainage channel 1-2 is circumferentially uniformly distributed and penetrated along the anchor body 1-1 and arranged inside the anchor body 1-1, and is tightly embedded in the grouting body 1-3, and is hydraulically connected to the groundwater in the soil layer through the drainage holes 1-2-1, and is not hydraulically connected to the grouting body 1-3 through the sealing material; pore water pressure sensors are arranged in some of the drainage holes 1-2-1, and the permeable stone on the surface of the pore water pressure sensor is tightly fitted with the soil layer.

[0046] The grouting bag includes an end grouting bag 1-5-1 and an intermediate grouting bag 1-5-2; the end grouting bag 1-5-1 is arranged at the end of the anchor rod body 1-1, and a plurality of intermediate grouting bags 1-5-2 are arranged circumferentially at a certain interval on the outside of the anchor rod body 1-1; the end grouting bag 1-5-1 and the intermediate grouting bag 1-5-2 are connected to the grouting body 1-3 through the grouting hole 1-1-1.

[0047] The bag-enlarged drainage anchor rod 1 is radially arranged below the water storage tank 3 along the cross-section of the shield tunnel 5 through a waterproof layer 3-1, annular steel beams 1-6 and longitudinal steel beams 1-7, and the top of the bag-enlarged drainage anchor rod 1 is located in the water storage tank 3; the top of the bag-enlarged drainage anchor rod 1 is sealed by an anchor head 1-1-2 and a fixing bolt 1-1-3, a drainage through hole is left in the anchor head 1-1-2 area where the drainage channel 1-2 is located, and a grouting through hole is left in the anchor head 1-1-2 area where the grouting body 1-3 is located.

[0048] The drainage pump 2 is located in the water storage tank 3, and is hydraulically connected to the drainage channel 1-2 through the drainage through hole and the water pipe on the anchor head 1-1-2; the power of the drainage pump 2 is determined by the drainage design flow rate, and can operate normally with or without water.

[0049] The water tank 3 is located at the bottom of the shield tunnel 5, and is separated from the traffic space and ancillary equipment space in the shield tunnel 5 by the side plates around the water tank 3 and the tunnel bottom plate 4; a waterproof layer 3-1 is laid on the bottom and sides of the water tank 3 to prevent water in the water tank 3 from seeping into the soil layer and other areas of the shield tunnel 5; the volume of the water tank 3 is determined by the drainage design requirements, the traffic space and ancillary equipment space of the shield tunnel 5; the strength of the side plates around the water tank 3 and the strength of each connection should meet the design requirements; the water tank 3 has a certain storage and drainage capacity, and the buoyancy of the shield tunnel 5 is coordinated by the water storage in the water tank 3 and the drainage of the bag-expanded drainage anchor rod 1.

[0050] A certain number of displacement sensors are arranged on the tunnel floor 4 and the shield tunnel 5 .

[0051] The control system includes a signal acquisition instrument and an alarm; the control system is connected to a pore water pressure sensor, a displacement sensor and a drainage pump 2; the acquisition instrument can automatically read and save the pore water pressure data in the bottom soil layer of the shield tunnel 5 through the pore water pressure sensor, and automatically read and save the displacement data of the shield tunnel 5 through the displacement sensor, and the displacement data of the shield tunnel 5 includes the buoyancy and buoyancy rate data of the tunnel; the alarm can read, warn and process the collected pore water pressure data and displacement data.

[0052] Specifically, the anchor body 1-1 is a steel pipe; the grouting bag material is a PVC film bag or other high-strength high-polymer film bag; the length, number and outer diameter of the bag-enlarged drainage anchor 1, the diameter, spacing and number of the drainage holes 1-2-1, and the water flow rate of the drainage channel 1-2 are determined by the drainage design flow rate; the volume of the grouting bag, the number and spacing of the intermediate grouting bags 1-5-2 are determined by the pull-out resistance design; the number and distribution of the pore water pressure sensors and displacement sensors are determined by the monitoring design of the shield tunnel 5; the contact between the bag-enlarged drainage anchor 1 and the bottom pipe segment of the shield tunnel 5 is sealed to prevent water leakage accidents.

[0053] Specifically, a drainage board is laid in the drainage channel 1-2, and is isolated from the grouting body 1-3 by a PVC board or other high-strength high-polymer material, and is not hydraulically connected.

[0054] This embodiment also provides a construction method for a shield tunnel decompression drainage anti-floating comprehensive treatment system, the method comprising the following steps:

[0055] (1) The shield tunnel's decompression, drainage and anti-floating comprehensive management system is installed in sections where there is a risk of floating due to abundant groundwater and intensive underground space development and construction activities.

[0056] (2) A water storage tank 3 is formed at the bottom of the shield tunnel 5 through the tunnel floor 4 and the surrounding side plates, a waterproof layer 3-1 is laid at the bottom and surrounding side of the water storage tank 3, and an annular steel beam 1-6 and a longitudinal steel beam 1-7 are installed on the waterproof layer 3-1 at the bottom of the water storage tank 3; after drilling holes at the bottom of the water storage tank 3, the annular steel beam 1-6 and the longitudinal steel beam 1-7 according to the design requirements, the anchor rod body 1-1 arranged with the grouting bag, the drainage channel 1-2 and the pore water pressure sensor is installed in the drilled hole, the steel bar 1-4 is inserted, and the anchor head 1-1-2 with the grouting through hole and the drainage through hole is installed, and grouting is performed. According to the grouting pressure feedback, the grouting pressure is adjusted in real time. After the gaps in the end grouting bag 1-5-1, the middle grouting bag 1-5-2 and the anchor rod body 1-1 are filled with pressurized slurry, the grouting is stopped, the fixing bolts 1-1-3 are installed to seal, and the grouting through hole is closed to complete the installation of the bag expansion type drainage anchor rod 1;

[0057] Specifically, according to the different drainage designs of various sections of the shield tunnel 5, partitions can be set at the junctions of the sections, and bag-expanded drainage anchor rods 1 with a suitable number of drainage channels 1-2 and intermediate grouting bags 1-5-2 can be installed. Drainage pumps 2 with matching power are selected to form section water tanks 3 with different drainage and anti-buoyancy capabilities along the shield tunnel 5.

[0058] Specifically, the waterproof layer 3-1 is a flexible waterproof layer, which is convenient for maintenance and replacement during the long-term operation stage; the pressure of the pressurized slurry filling the gaps in the end grouting bag 1-5-1, the middle grouting bag 1-5-2 and the anchor body 1-1 is determined by the pull-out resistance design, as well as the bag volume and strength.

[0059] (3) Install the drainage pump 2 in the water storage tank 3, and connect the drainage through hole on the anchor head 1-1-2 and the drainage pump 2 through a water pipe.

[0060] (4) a certain number of displacement sensors are arranged on the tunnel floor 4 and the shield tunnel 5; the control system is connected to the pore water pressure sensor, the displacement sensor and the drainage pump (2); the data of the pore water pressure sensor and the displacement sensor are automatically read and saved by the data acquisition instrument of the control system, and the collected pore water pressure data and displacement data are read, warned and processed by the alarm of the control system;

[0061] Specifically, the control system reserves an interface for connecting to an underground space intelligent monitoring system to provide operation and maintenance monitoring data for the service life of the shield tunnel.

[0062] (5) Controlling the shield tunnel to float up through the coordinated action of the bag-enlarged drainage anchor rod 1, drainage pump 2, water storage tank 3 and control system;

[0063] When the excess pore water pressure in the soil layer or the buoyancy or buoyancy rate of the tunnel collected by the collector of the control system exceeds the tunnel buoyancy warning value, the alarm sounds and automatically starts the drainage pump 2 to pump water, timely reducing the pore water pressure in the soil layer at the bottom of the shield tunnel 5 to reduce the buoyancy of the shield tunnel 5, and at the same time increasing the water storage capacity in the water storage tank 3 to increase the deadweight of the shield tunnel 5; according to the real-time collected excess pore water pressure or the buoyancy or buoyancy rate data of the tunnel, the operating power of the drainage pump 2 is adjusted in real time until the buoyancy risk of the shield tunnel 5 is eliminated;

[0064] When the excess pore water pressure in the soil layer collected by the data collector of the control system conflicts with the displacement (floating amount or floating rate) data of the tunnel, the displacement (floating amount or floating rate) data of the tunnel shall prevail;

[0065] Specifically, the operating power of the drainage pump 2, the increased water storage capacity in the water storage tank 3 and the rate of increasing the water storage capacity are determined by the design.

[0066] The technical principle of the present invention is described above in conjunction with specific embodiments. These descriptions are only for explaining the principle of the present invention and cannot be interpreted as limiting the scope of protection of the present invention in any way. Based on the explanations herein, those skilled in the art can associate other specific implementations of the present invention without paying creative labor, and these methods will fall within the scope of protection of the present invention.

Claims

1. A shield tunnel decompression drainage anti-floating comprehensive management system, characterized by: It comprises a bag-expanding drainage anchor rod (1), a drainage pump (2), a water storage tank (3) and a control system; The bag-enlarged drainage anchor rod (1) is composed of an anchor rod body (1-1), a drainage channel (1-2), a grouting body (1-3), steel bars (1-4) and a grouting bag; the anchor rod body (1-1) is circumferentially staggered with uniformly distributed grouting holes (1-1-1) and drainage holes (1-2-1); the drainage channel (1-2) is arranged inside the anchor rod body (1-1), and the remaining space is arranged from the outside to the inside with the grouting body (1-3) and steel bars (1-4) arranged inside the anchor rod body (1-1). ); the drainage channel (1-2) is evenly distributed in the annular direction and is arranged along the anchor body (1-1) on the inner side of the anchor body (1-1), and is tightly embedded in the grouting body (1-3), and is hydraulically connected to the groundwater in the soil layer through the drainage hole (1-2-1), and is hydraulically disconnected from the grouting body (1-3) through the sealing material; pore water pressure sensors are arranged in some of the drainage holes (1-2-1), and the permeable stone on the surface of the pore water pressure sensor is tightly fitted with the soil layer; The grouting bag comprises an end grouting bag (1-5-1) and an intermediate grouting bag (1-5-2); the end grouting bag (1-5-1) is arranged at the end of the anchor rod body (1-1), and a plurality of intermediate grouting bags (1-5-2) are arranged circumferentially outside the anchor rod body (1-1) at a certain interval; the end grouting bag (1-5-1) and the intermediate grouting bag (1-5-2) are connected to the grouting body (1-3) through the grouting hole (1-1-1); The bag-enlarged drainage anchor rod (1) is radially arranged below the water storage tank (3) along the cross section of the shield tunnel (5) through a waterproof layer (3-1), an annular steel beam (1-6) and a longitudinal steel beam (1-7), and the top of the bag-enlarged drainage anchor rod (1) is located in the water storage tank (3); the top of the bag-enlarged drainage anchor rod (1) is sealed by an anchor head (1-1-2) and a fixing bolt (1-1-3), a drainage through hole is left in the anchor head (1-1-2) region where the drainage channel (1-2) is located, and a grouting through hole is left in the anchor head (1-1-2) region where the grouting body (1-3) is located; The downdraft pump (2) is located in the water storage tank (3) and is hydraulically connected to the drainage channel (1-2) through the drainage through hole and the water pipe on the anchor head (1-1-2); The water storage tank (3) is located at the bottom of the shield tunnel (5) and is separated from the traffic space and auxiliary equipment space in the shield tunnel (5) by the side plates around the water storage tank (3) and the tunnel bottom plate (4); a waterproof layer (3-1) is laid on the bottom and sides of the water storage tank (3) to prevent the water in the water storage tank (3) from seeping into the soil layer and other areas of the shield tunnel (5); the shield tunnel (5) is buoyed by the water storage tank (3) and the drainage of the bag expansion type drainage anchor rod (1); A plurality of displacement sensors are arranged on the tunnel floor (4) and the shield tunnel (5); The control system comprises a signal acquisition instrument and an alarm; the control system is connected to a pore water pressure sensor, a displacement sensor and a drainage pump (2); the acquisition instrument can automatically read and save pore water pressure data in the soil layer at the bottom of the shield tunnel (5) through the pore water pressure sensor, and automatically read and save displacement data of the shield tunnel (5) through the displacement sensor, wherein the displacement data of the shield tunnel (5) comprises the buoyancy and buoyancy rate data of the tunnel; the alarm can read, warn and process the collected pore water pressure data and displacement data.

2. The shield tunnel decompression drainage and anti-floating comprehensive treatment system according to claim 1 is characterized by: The anchor rod body (1-1) is a steel pipe; the grouting bag material is a PVC film bag or other high-strength high-polymer film bag; the length, number and outer diameter of the bag-enlarged drainage anchor rod (1), the diameter, spacing and number of the drainage holes (1-2-1), and the water flow rate of the drainage channel (1-2) are determined by the drainage design flow rate; the volume of the grouting bag, the number and spacing of the intermediate grouting bags (1-5-2) are determined by the pull-out resistance design; the number and distribution of the pore water pressure sensors and displacement sensors are determined by the monitoring design of the shield tunnel (5); the contact between the bag-enlarged drainage anchor rod (1) and the bottom pipe segment of the shield tunnel (5) is sealed to prevent water leakage accidents.

3. The shield tunnel decompression drainage and anti-floating comprehensive treatment system according to claim 1 is characterized by: A drainage board is laid in the drainage channel (1-2), and is isolated from the grouting body (1-3) by a PVC board or other high-strength high-polymer material, and is not hydraulically connected.

4. The shield tunnel decompression drainage and anti-floating comprehensive treatment system according to claim 1 is characterized by: The power of the downdraft pump (2) is determined by the downdraft design flow rate; the downdraft pump (2) can operate normally in the presence or absence of water.

5. The shield tunnel decompression drainage and anti-floating comprehensive treatment system according to claim 1 is characterized by: The volume of the water storage tank (3) is determined by the drainage design requirements, the traffic space of the shield tunnel (5) and the auxiliary equipment space; the strength of the surrounding side plates of the water storage tank (3) and the strength of each connection should meet the design requirements.

6. A construction method for the shield tunnel decompression, drainage and anti-floating comprehensive treatment system according to any one of claims 1 to 5, characterized in that: The method comprises the following steps: (1) In the sections where the shield tunnel passes through which there is abundant groundwater and intensive underground space development and construction activities, and where there is a risk of floating, a decompression and drainage anti-floating comprehensive management system for the shield tunnel is installed; (2) A water storage tank (3) is formed at the bottom of the shield tunnel (5) through the tunnel floor (4) and the surrounding side plates, a waterproof layer (3-1) is laid at the bottom and surrounding side of the water storage tank (3), and an annular steel beam (1-6) and a longitudinal steel beam (1-7) are installed on the waterproof layer (3-1) at the bottom of the water storage tank (3); after drilling holes at the bottom of the water storage tank (3), the annular steel beam (1-6) and the longitudinal steel beam (1-7) according to design requirements, anchor rods with grouting bags, drainage channels (1-2) and pore water pressure sensors are arranged. The main body (1-1) is installed in the drilled hole, the steel bar (1-4) is inserted, and the anchor head (1-1-2) with the grouting through hole and the drainage through hole is installed, and then grouting is performed. According to the grouting pressure feedback, the grouting pressure is adjusted in real time. After the gaps in the end grouting bag (1-5-1), the middle grouting bag (1-5-2) and the anchor body (1-1) are filled with pressurized grouting liquid, the grouting is stopped, the fixing bolts (1-1-3) are installed for sealing, and the grouting through hole is closed, thereby completing the installation of the bag-enlarged drainage anchor (1); (3) installing the drainage pump (2) in the water storage tank (3), and connecting the drainage through hole on the anchor head (1-1-2) and the drainage pump (2) via a water pipe; (4) a plurality of displacement sensors are arranged on the tunnel floor (4) and the shield tunnel (5); a control system is connected with the pore water pressure sensor, the displacement sensor and the drainage pump (2); data of the pore water pressure sensor and the displacement sensor are automatically read and saved by a data acquisition device of the control system, and the collected pore water pressure data and displacement data are read, warned and processed by an alarm device of the control system; (5) controlling the shield tunnel to float upward through the coordinated action of the bag-expanded drainage anchor rod (1), the drainage pump (2), the water storage tank (3) and the control system; When the excess pore water pressure in the soil layer or the buoyancy or buoyancy rate of the tunnel collected by the collection instrument of the control system exceeds the tunnel buoyancy warning value, the alarm alarms and automatically starts the drainage pump (2) to pump water, timely reducing the pore water pressure in the soil layer at the bottom of the shield tunnel (5) to reduce the buoyancy of the shield tunnel (5), while increasing the water storage capacity in the water storage tank (3) to increase the deadweight of the shield tunnel (5); according to the real-time collected excess pore water pressure or the buoyancy or buoyancy rate data of the tunnel, the operating power of the drainage pump (2) is adjusted in real time until the risk of buoyancy of the shield tunnel (5) is eliminated.

7. The construction method of a shield tunnel decompression drainage anti-floating comprehensive treatment system according to claim 6, characterized in that: In the steps (1) and (2), the water storage tank (3) can be provided with a partition plate at the junction of the sections according to the different drainage designs of the sections of the shield tunnel (5), and a bag-enlarged drainage anchor rod (1) with a suitable number of drainage channels (1-2) and intermediate grouting bags (1-5-2) can be installed, and a drainage pump (2) with matching power can be selected to form section water storage tanks (3) with different drainage and anti-buoyancy capabilities along the shield tunnel (5).

8. The construction method of a shield tunnel decompression drainage anti-floating comprehensive treatment system according to claim 6, characterized in that: In the step (2), the waterproof layer (3-1) is a flexible waterproof layer, which is convenient for maintenance and replacement during the long-term operation stage; the pressure of the pressurized grouting liquid filling the gaps in the end grouting bag (1-5-1), the middle grouting bag (1-5-2) and the anchor body (1-1) is determined by the pull-out resistance design, as well as the volume and strength of the bag.

9. The construction method of a shield tunnel decompression drainage anti-floating comprehensive treatment system according to claim 6, characterized in that: In the step (4), the control system reserves an interface to connect to the underground space intelligent monitoring system to provide operation and maintenance monitoring data of the shield tunnel during its service life.

10. The construction method of a shield tunnel decompression drainage anti-floating comprehensive treatment system according to claim 6, characterized in that: In the step (5), when the excess pore water pressure in the soil layer collected by the collector of the control system conflicts with the displacement data of the tunnel, the displacement data of the tunnel shall prevail; the operating power of the drainage pump (2), the increased water storage capacity in the water storage tank (3) and the rate of increasing the water storage capacity are determined by the design.

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