Construction structure and method of shield end start under space-constrained conditions

Abstract

The present invention relates to a construction structure and method for starting a shield end under space-constrained conditions, the structure comprising a cement reinforcement system and a simple short sleeve; the cement reinforcement system comprises a mixing pile, the inner side of the mixing pile is a jet grouting pile; the simple short sleeve is located inside the jet grouting pile and arranged longitudinally, comprising a transition ring connected to the jet grouting pile, the upper inner side of the transition ring is sequentially a middle upper semicircular ring and a tail upper semicircular ring, and the lower side is sequentially a tail lower semicircular ring and a middle lower semicircular ring. The invention uses a self-made simple short sleeve to extend the starting space when the space is limited, greatly reducing unnecessary storage and transportation risks of conventional steel sleeve construction methods, reducing engineering costs, shortening construction periods, using cement reinforcement to improve the soil in the end range, actively cutting off hydraulic connections, avoiding water and sand gushing, and thus improving the starting safety, having obvious advantages, and being highly adaptable.

Description

Technical Field

[0001] The invention belongs to the technical field of tunnel engineering, and in particular relates to a construction structure and method for starting from a shield end under space-constrained conditions. Background Art

[0002] The shield method has become the main construction method for urban subway construction. In soft soil areas, due to the loose and permeable soil, in the initial stage of shield construction, in order to avoid accidents such as sand gushing and collapse, the end reinforcement is required to improve the bearing capacity of the end foundation and play a role in stopping water at the station portal. Conventional end reinforcement in soft soil areas is mostly carried out by mixing piles. The length of the mixing pile reinforcement is controlled by the mechanical size of the shield machine and the stability of the face soil, and a certain length range is required. However, under the condition of limited end well space, such as near the river, close to buildings that cannot be demolished or pipelines that cannot be relocated, there is often no space for ground reinforcement on site. In similar projects in recent years, when reinforcement construction is difficult, more and more steel sleeves are used to replace end ground reinforcement. Although it has strong adaptability, it also has unavoidable disadvantages such as long installation period, difficult storage and transportation, and high cost. At the same time, there are still risks of water and sand gushing in the front soil. Summary of the invention

[0003] The purpose of the present invention is to provide a construction structure and method for starting from the end of a shield machine under space-constrained conditions, so as to solve the problem of no reinforcement space when the end well space is limited, such as near a river, close to buildings that cannot be demolished, and when pipelines cannot be relocated.

[0004] The technical solution adopted by the present invention is:

[0005] The construction structure initiated from the end of the shield under space-constrained conditions is characterized by:

[0006] The structure includes a cement reinforcement system and a simple short sleeve;

[0007] The cement reinforcement system includes mixing piles, and the inner side of the mixing piles is a jet-jet pile;

[0008] The simple short sleeve is located inside the jet grouting pile and arranged longitudinally, including a transition ring connected to the jet grouting pile, the upper inner part of the transition ring is sequentially a middle upper semicircular ring and a tail upper semicircular ring, and the lower part is sequentially a tail lower semicircular ring and a middle lower semicircular ring.

[0009] An embedded ring plate is arranged on the inner side of the rotary jet pile, and the transition ring is welded and fixed to the embedded ring plate.

[0010] The middle upper semicircular ring and the tail upper semicircular ring, as well as the middle upper semicircular ring and the transition ring are connected and fixed by flanges and bolts arranged at the joint surfaces, with a rubber pad sandwiched in between;

[0011] The lower semicircular ring at the tail end and the lower semicircular ring in the middle, as well as the lower semicircular ring at the tail end and the transition ring are connected and fixed by flanges and bolts arranged at the joint surfaces, with a rubber pad sandwiched in between.

[0012] The middle upper semicircular ring and the tail upper semicircular ring form an upper semicircular cylinder, the tail lower semicircular ring and the middle lower semicircular ring form a lower semicircular cylinder, and the upper semicircular cylinder and the lower semicircular cylinder are connected and fixed by bolts.

[0013] The semicircular ring includes two layers of circumferential end plates, a transverse bottom plate and a longitudinal rib plate are arranged between the end plates, and longitudinal bolt holes are arranged on the bottom plate;

[0014] The semicircular ring is divided into multiple sections, and the ribs on the end faces of each section are provided with annular bolt connections.

[0015] The bottom of the lower semicircular cylinder is supported by a base.

[0016] The middle upper semicircular ring is connected and fixed to the transition ring by longitudinal steel supports.

[0017] An initial water-stop device is arranged between the transition ring and the embedded ring plate. The initial water-stop device includes a gasket and a fan-shaped circular ring plate, which is fixed to the embedded ring plate by bolts and nuts. A cord rubber plate is arranged between the gasket and the embedded ring plate, and a flap is hinged on the circular ring plate.

[0018] The inner bottom surface of the simple short sleeve is provided with two tracks which are connected to the guide rail outwards.

[0019] The construction method based on the structure implemented in the space-constrained condition of shield end start is characterized by:

[0020] The method comprises the following steps:

[0021] Step 1: Carry out the mixing pile reinforcement according to the distribution of the end aquifer and the calculation of soil stability, and finally set a row of jet grouting piles between the station enclosure structure and the mixing pile reinforcement body;

[0022] Step 2: After the reinforcement is completed, determine the center line of the shield body at the wellhead of the shield, weld and install the transition ring on the embedded ring plate of the station enclosure structure, and apply polyurethane on the outer side of the transition ring and the embedded ring plate to strengthen waterproofing. If there is a large gap between the transition ring and the embedded ring plate, fill the gap with steel plates and weld it firmly again; install the lower half of the simple short sleeve so that its center line coincides with the center line of the shield body, and connect the lower half of the ring with the transition ring with bolts;

[0023] Step 2: Install 2 43 kg steel rails evenly distributed in the 60° arc below the installed simple short sleeve. The steel rails are laid from the rear end of the lower semicircular ring steel sleeve to the transition ring. The steel rails are fixed with a pressure plate, which is welded to the lower semicircular ring cylinder. According to the elevation of the shield machine, install 2 guide rails at the lower part of the tunnel portal, and make a slope near the end of the shield machine. The height slope of the guide rail is consistent with that of the rail surface on the base. To ensure that the bottom sand layer provides sufficient anti-torsion friction reaction force for the shield machine, sand is laid between the 2 steel rails at the bottom of the steel sleeve and compacted. The height of the sand at each position is 15 mm higher than the height of the corresponding steel rail. After the shield machine is put on, further compaction is performed.

[0024] Step 3: Install the front shield and middle shield of the shield machine. Place them in the lower semicircular steel sleeve. After the front shield and middle shield are installed, ensure that there is a 50cm operating space between the front end of the front shield and the tail of the assembled simple short sleeve to facilitate the installation of the rubber curtain plate and the curtain pressure plate.

[0025] Step 4: After the filling material is installed on the inner guide rail of the lower semicircle of the simple short sleeve, the upper semicircle ring and support at the tail end of the steel sleeve can be installed; the upper semicircle ring at the tail end of the steel sleeve is connected to the lower semicircle of the steel sleeve by bolts, and the distance between the upper semicircle ring at the tail end and the steel ring of the tunnel gate is 2.5 meters, and 5 I-beams are used for support and reinforcement;

[0026] Step 5: Install the initial water stop device at the tail of the steel sleeve. The water stop device includes a curtain rubber plate, a circular ring plate, bolts, nuts and washers. The tail ring plate of the steel sleeve has 72 bolt holes reserved. Measure the position deviation of the screw holes before installation. If the deviation is too large, adjust the position of the holes on the curtain rubber plate accordingly. At the same time, clean the inner threads of the screw holes one by one and evenly apply butter on the inside. When installing, install the curtain rubber plate first, then the circular ring plate. The bolts should be tightened as much as possible to make the curtain rubber plate close to the steel sleeve, and then turn the circular ring plate into the steel sleeve.

[0027] After the installation is completed, wait for the front shield of the shield machine to be pushed into the steel sleeve by the jack, and weld the arc-shaped steel plate of the lower half of the steel sleeve, and take preventive measures in advance;

[0028] Step 6: After the rubber curtain plate is installed, use two 200T jacks to push the front shield and the middle shield into the steel sleeve. After they are in place, the upper I-beam support can be removed; then hoist the cutterhead, install the shield machine body in the steel sleeve, and connect it with the connecting bridge and the rear supporting trolley; the guide rail inside the steel ring of the tunnel portal is 20cm long, and 60cm of space is reserved to ensure the rotation of the cutterhead and smooth debugging; after the debugging of the shield machine is completed, the upper half of the simple short sleeve can be installed;

[0029] Step 7: After the steel sleeve and reaction frame are installed and the shield machine is debugged, the negative ring is installed and the shield machine is advanced until the cutterhead panel is close to the tunnel face but does not cut the tunnel face; after the first negative ring is assembled in the shield tail, it is pushed backward as a whole by a jack until it is close to the reaction frame, and the pipe segment and the reaction frame are connected by bolts;

[0030] Step 8: After the installation and commissioning of the shield machine is completed, the upper half of the simple short sleeve can be installed; after the upper half of the simple short sleeve is installed, adjust the tightening bolts and check the connection and installation parts to ensure the integrity of the connection; at the connection between the upper and lower semicircles of the steel sleeve, the inner side is affixed with a water-expandable water stop strip, and the inner and outer sides are coated with polyurethane to prevent leakage;

[0031] Step 9: Sealing the tail of the simple short sleeve and the pipe segment; after the shield tail enters the steel sleeve, use the arc steel plate to weld the end of the steel sleeve to the back arc surface of the pipe segment with the -2 ring back-covering steel plate to ensure full welding; 15cm long D28mm steel bars can be added to the outside of the arc steel plate as diagonal braces for reinforcement;

[0032] Step 10: The shield machine moves forward until the cutterhead panel is close to the edge of the reinforcement area, that is, the 0-ring segment is assembled, and the second sand filling is carried out into the steel sleeve through the feed port at the top of the steel sleeve. This time, the filler is filled with sand in the gap between the steel sleeve and the shield; during the filling process, add water appropriately and discharge it through the drainage hole at the bottom of the steel sleeve to ensure the density of the sand;

[0033] At this stage, the shield machine continues to excavate and fill sand simultaneously until the 0-ring segment is separated from the shield tail; to ensure that the segments in the simple short sleeve do not sink, the filler in the steel sleeve must be dense and uniform. During the filling process, it must be filled in multiple filling holes to ensure uniform distribution. The filling process is carried out in stages, and people are sent to observe at the filling holes. When it is filled to a certain height, it needs to be leveled and compacted. After leveling, continue to fill until the entire simple short sleeve is completely filled;

[0034] Step 11: During the shield advancement process, when the shield tail is separated from the steel sleeve, the hardenable slurry is injected synchronously through the grouting pipe of the shield machine to fill the gap;

[0035] When the cutterhead excavates to the +18th ring segment assembly, the machine should be stopped and the grouting holes of the segment should be used to perform secondary grouting at the 0th, 2nd, 4th, 6th and 8th rings respectively, injecting cement-water-glass double liquid slurry;

[0036] Step 12: When the shield machine has excavated to 100 rings, remove the simple short sleeve; before removal, check the sealing condition of the tunnel door through the detection hole to ensure that the grouting effect meets the requirements; according to the principle of "sealing as you cut", weld the arc steel plate to the back steel plate of the +1 ring segment.

[0037] The present invention has the following advantages:

[0038] The present invention adopts a simple short sleeve assembly in the method of realizing the shield end reinforcement and starting under space-constrained conditions, adopts water-stop curtain cloth for sealing and water-stopping, adopts mixing piles for foundation reinforcement, and rotary jet piles for joint water-stopping. The steel, cement slurry, mixing machinery, trolleys, welding equipment and fixed anchor bolts involved in the above are all conventional materials or equipment, and their corresponding sizes are conventional types in engineering, which are convenient for processing, manufacturing and procurement. Under the condition of limited end space, the mixing reinforcement length can be dynamically adjusted according to the stability of the soil in front and the geological conditions on site. The slurry ratio can be processed, and multi-point supplementary reinforcement can be carried out according to the water-stopping effect of the interface, and dynamic optimization and adjustment can be carried out, which has strong operability.

[0039] Since the shield method is a common construction method in the construction of urban rail transit projects, the present invention has many advantages of steel sleeves and cement reinforcement. When the space is limited, a simple assembled short sleeve is used to extend the starting space, and the ground reinforcement improves the soil in the end range, actively cuts off the hydraulic connection, avoids water and sand gushing, and thus improves the starting safety. At the same time, the use of a simple short sleeve reduces unnecessary storage and transportation risks, reduces the project cost, shortens the construction period, has obvious advantages, and is highly adaptable. Conventional mixing piles are used for soil reinforcement, actively improve the soil to improve stability and impermeability, and jet grouting piles are used to close the interface of water infiltration, actively isolate the hydraulic connection to avoid water and sand gushing, and improve the starting safety; secondly, the simple short sleeve method is used to extend the shield starting space, solving the problem of no reinforcement space when the end well space is limited, such as near the river, close to buildings that cannot be demolished, or pipelines that cannot be relocated.

[0040] The invention has flexible application conditions, strong adaptability, and can meet the stringent requirements of surrounding environmental protection. Therefore, the invention has high economic and social benefits and has broad application prospects in the urban rail transit industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a schematic diagram of a simple short sleeve structure.

[0042] Figure 2 This is a longitudinal schematic diagram of the upper half ring and support reinforcement at the tail end of the steel sleeve.

[0043] Figure 3 This is a schematic diagram of the upper half ring and support reinforcement section at the rear end of the steel sleeve.

[0044] Figure 4 This is a structural diagram of a simple short sleeve transition ring.

[0045] Figure 5 This is a structural diagram of the upper half ring of a simple short sleeve.

[0046] Figure 6This is the structural diagram of the lower half ring of a simple short sleeve.

[0047] Figure 7 This is a schematic diagram of the shield tunneling starting water-stop device.

[0048] Figure 8 This is the structural details of the shield starting water-stop device.

[0049] Fig. 9 This is a diagram of the arc steel plate sealing structure.

[0050] Fig.10 It is a single curved steel plate.

[0051] Fig.11 This is the sample of mixing pile.

[0052] Fig.12 This is the sample of rotary jet grouting pile.

[0053] In the figure, 1-transition ring, 2-embedded ring plate, 3-starting bracket, 4-reaction frame, 5-negative ring, 6-I-beam, 7-upper semicircular ring at the tail end, 8-lower semicircular ring at the tail end, 9-mixing pile, 10-jet pile, 11-steel support, 12-base, 13-spiral welded pipe, 14-cord rubber sheet, 15-flap, 16-bolt, 17-washer, 18-circular ring plate, 19-nut, 20-arc steel plate, 21-segment, 22-ground connected wall, 23-end plate, 24-rib plate, 25-longitudinal bolt hole, 26-circumferential bolt connection, 27-single arc steel plate, 28-middle upper semicircular ring, 29-middle lower semicircular ring, 30-circumferential connecting steel plate. DETAILED DESCRIPTION

[0054] The present invention is described in detail below in conjunction with specific implementation modes.

[0055] The invention relates to a construction structure for starting a shield end under space-constrained conditions, which has many advantages of cement reinforcement and steel sleeves. When the space is limited, a simple short sleeve is used to extend the starting space, which greatly reduces unnecessary storage and transportation risks of conventional steel sleeve construction methods, reduces the project cost, shortens the construction period, and uses cement reinforcement to improve the soil in the end range, actively cuts off hydraulic connections, avoids water and sand gushing, and thus improves the starting safety. The invention has obvious advantages and is highly adaptable.

[0056] The structure includes a cement reinforcement system and a simple short sleeve; the cement reinforcement system includes a mixing pile 9, and the inner side of the mixing pile 9 is a rotary jet pile 10; the simple short sleeve is located inside the rotary jet pile 10 and is arranged longitudinally, including a transition ring 1 connected to the rotary jet pile 10, and the upper inner part of the transition ring 1 is sequentially composed of a middle upper semicircular ring 28 and a tail upper semicircular ring 7, and the lower part is sequentially composed of a tail lower semicircular ring 8 and a middle lower semicircular ring 29.

[0057] The inner side of the jet grouting pile 10 is provided with an embedded ring plate 2, and the transition ring 1 is welded and fixed to the embedded ring plate 2. The middle upper semicircular ring 28 and the tail upper semicircular ring 7, and the middle upper semicircular ring 28 and the transition ring 1 are connected and fixed by flanges and bolts provided at the joint surface, and a rubber pad is sandwiched in the middle; the tail lower semicircular ring 8 and the middle lower semicircular ring 29, and the tail lower semicircular ring 8 and the transition ring 1 are connected and fixed by flanges and bolts provided at the joint surface, and a rubber pad is sandwiched in the middle.

[0058] The middle upper semicircular ring 28 and the tail upper semicircular ring 7 form an upper semicircular cylinder, and the tail lower semicircular ring 8 and the middle lower semicircular ring 29 form a lower semicircular cylinder. The upper semicircular cylinder and the lower semicircular cylinder are connected by bolts.

[0059] The semicircular ring includes two circumferential end plates 23, a transverse bottom plate and longitudinal ribs 24 are arranged between the end plates 23, and a longitudinal bolt hole 25 is arranged on the bottom plate; the semicircular ring is divided into multiple sections, and the ribs 24 on the end face of each section are provided with circumferential bolt connections 26.

[0060] The bottom of the lower semicircular ring cylinder is supported by a base 12. The middle upper semicircular ring 28 is connected and fixed to the transition ring 1 by a longitudinal steel support 11.

[0061] An initial water-stop device is arranged between the transition ring 1 and the embedded ring plate 2. The initial water-stop device includes a gasket 17 and a fan-shaped circular ring plate 18, which is fixed to the embedded ring plate 2 by bolts 16 and nuts 19. A cord rubber plate 14 is arranged between the gasket 17 and the embedded ring plate 2, and a flap 15 is hinged on the circular ring plate 18.

[0062] The inner bottom surface of the simple short sleeve is provided with two tracks which are connected to the guide rail outwards.

[0063] The present invention is further described in detail with reference to the accompanying drawings:

[0064] The simple short sleeve includes a transition ring 1, a lower semicircular ring, an upper semicircular ring and other main assembly components and a simple sleeve tail water-stop component; the cement reinforcement system includes a mixing pile 9 reinforcement and a rotary jet pile 10 joint water-stop;

[0065] The transition ring 1 is used to connect with the end of the simple short sleeve and the ground connection wall 22. The transition ring 1 is welded and installed on the embedded ring plate 2 of the station enclosure structure. Polyurethane is applied to the outer side of the transition ring 1 and the embedded ring plate 2 to enhance waterproofing. If there is a large gap between the transition ring 1 and the embedded ring plate 2, fill the gap with a steel plate and weld it firmly again.

[0066] The upper semicircular ring is used to assemble the middle main steel sleeve of the simple short sleeve, which is divided into the middle upper semicircular ring 28 and the tail upper semicircular ring 7. The shield body, the tail upper semicircular ring 7 and the transition ring 1, and the joint surface with the lower semicircular ring are all welded with round flanges. The upper semicircular ring steel cylinder and the transition ring 1 and the lower semicircular ring cylinder are connected by bolts using round flanges, and a rubber gasket is added in the middle for sealing;

[0067] The lower semicircular ring is used to assemble the middle main steel sleeve of the simple short sleeve, which is divided into the middle lower semicircular ring 29 and the tail lower semicircular ring 8. The end and the transition ring 1 and the upper semicircular ring joint surface are welded with round flanges. The lower semicircular ring steel cylinder and the transition ring 1 and the upper semicircular ring cylinder are connected by bolts using round flanges, and a rubber gasket is added in the middle for sealing;

[0068] The simple sleeve tail water stop device includes a curtain rubber plate 14, a sector-shaped circular plate 18, a connecting bolt 16, a nut 19 and a washer 17. The tail ring plate of the simple steel sleeve has 72 bolt holes reserved. The curtain rubber plate 14 is installed first, followed by the circular sector plate. The pressure plate bolts should be tightened as much as possible to make the curtain rubber plate 14 close to the steel sleeve, and then the sector plate is turned into the steel sleeve. Before installation, use a tap to clean the inner threads of the screw holes one by one, and evenly apply butter on the inside;

[0069] The cement mixing piles 9 are used to improve the soil at the outer end of the retaining structure and isolate the through water system to avoid water and sand gushing and insufficient soil stability after the shield machine opens the tunnel. The reinforcement length and bite degree are flexibly arranged according to the size of the restricted space, soil conditions, and the distribution of surrounding buildings and structures.

[0070] The jet grouting piles 10 are used for waterproofing the joints between the cement mixing piles 9 and the station enclosure structure. The bite degree and depth of the jet grouting piles 10 can be flexibly arranged and processed according to the on-site soil conditions, the isolated and connected water system, and the distribution of surrounding buildings and structures. The purpose is to cut off the water seepage path at the interface, avoid water and sand gushing, and improve the safety of the shield starting.

[0071] The shield reinforcement and launching method of the present invention has the following characteristics:

[0072] The present invention firstly uses conventional mixing piles 9 to reinforce the face soil, actively improves the soil to improve stability and impermeability, uses jet grouting piles 10 to close the interface of water infiltration, actively isolates the hydraulic connection to avoid water and sand gushing, and improves the safety of shield starting. A simple short sleeve is assembled in the station shield shaft to extend the starting space, and the main components such as the upper semicircular ring, the lower semicircular ring, and the transition ring 1 are assembled. Different components are connected by circular flanges, bolts and other components. Waterproofing is performed by arranging a curtain rubber plate 14 and a flap 15 on the simple sleeve, which greatly reduces the unnecessary storage and transportation risks of the conventional steel sleeve method, reduces the project cost, shortens the construction period, and has stronger adaptability.

[0073] The above-mentioned method for realizing the shield end starting under space-constrained conditions comprises the following steps:

[0074] Step 1: Carry out the reinforcement of mixing piles 9 according to the distribution of the end aquifer and the calculation of soil stability. Finally, set a row of jet grouting piles 10 between the station enclosure structure and the reinforcement of mixing piles 9 to play the role of interface water stop. The cement reinforcement is aimed at improving the soil and cutting off the hydraulic connection within the end range to isolate and protect the building. The reinforcement length can be flexibly arranged according to the end space size.

[0075] Step 2: After the reinforcement is completed, determine the center line of the shield body at the wellhead of the shield, weld and install the transition ring 1 on the embedded ring plate of the station enclosure structure, and apply polyurethane on the outer side of the transition ring 1 welded with the embedded ring plate to strengthen waterproofing. If there is a large gap between the transition ring 1 and the embedded ring plate, fill the gap with steel plates and weld it firmly again; install the lower semicircular ring of the simple sleeve so that its center line coincides with the center line of the shield body, and the lower semicircular ring and the transition ring 1 are connected with bolts;

[0076] Step 2: Install two 43 kg steel rails evenly distributed within a 60° arc below the installed simple steel sleeve. The rails are laid from the rear end of the lower semi-circular steel sleeve to the transition ring 1. The rails are fixed with a pressure plate, and the pressure plate is welded to the lower semi-circular cylinder. According to the elevation of the shield machine, two guide rails are installed at the bottom of the tunnel portal, and a slope is made near the end of the shield machine. The height slope of the guide rail is consistent with that of the rail surface on the base. In order to ensure that the bottom sand layer provides sufficient friction reaction force to prevent the shield machine from torsion, sand is spread and compacted between the two steel rails at the bottom of the steel sleeve. The height of the sand at each position is 15 mm higher than the height of the corresponding rail. After the shield machine is put on, it is further compacted;

[0077] Step 3: Install the front shield and middle shield of the shield machine. Place them in the lower semicircular steel sleeve. After the front shield and middle shield are installed, ensure that there is a 50cm operating space between the front end of the front shield and the rear end of the assembled simple steel sleeve to facilitate the installation of the rubber curtain plate and curtain pressure plate.

[0078] Step 4: After the filling is installed on the inner rail of the lower semicircle of the simple steel sleeve, the upper semicircle ring 7 and the support 11 at the tail end of the steel sleeve can be installed. The upper semicircle ring 7 at the tail end of the steel sleeve is connected to the lower semicircle of the steel sleeve by bolts. The distance between the upper semicircle ring 7 at the tail end and the steel ring of the tunnel gate is 2.5 meters, and 5 18a I-beams 11 are used for support and reinforcement;

[0079] Step 5: Install the initial water-stop device at the tail of the steel sleeve. The water-stop device includes a curtain rubber plate 14, a sector-shaped circular ring plate, connecting bolts, nuts and washers; the tail ring plate of the steel sleeve has 72 bolt holes reserved. Measure the position deviation of the screw holes before installation. If the deviation is too large, adjust the position of the holes on the curtain rubber plate 14 accordingly. At the same time, clean the inner threads of the screw holes one by one and evenly apply butter on the inside. During installation, install the curtain rubber plate 14 first, then the circular sector plate. The pressure plate bolts should be tightened as much as possible to make the curtain rubber plate 14 close to the steel sleeve, and then turn the sector plate into the steel sleeve.

[0080] After the rubber curtain plate and the pressure plate are installed, after the front shield of the shield machine is pushed into the steel sleeve by the jack, the arc-shaped steel plate 20 of the lower semicircle of the steel sleeve is welded, and preventive measures are taken in advance.

[0081] Step 6: After the rubber curtain plate is installed, use two 200T jacks to push the front shield and the middle shield into the steel sleeve. After they are in place, the upper 18a I-beam 6 support can be removed. Then hoist the cutterhead, install the shield machine body in the steel sleeve, and connect it to the connecting bridge and the rear supporting trolley. The length of the guide rail inside the portal steel ring is 20cm, and 60cm of space is reserved to ensure the rotation of the cutterhead and smooth debugging. The upper half of the simple steel sleeve can be installed only after the shield machine is debugged;

[0082] Step 7: After the steel sleeve and reaction frame 4 are installed and the shield machine is debugged, the negative ring 5 is installed and the shield machine is advanced until the cutterhead panel is close to the tunnel face but does not cut the tunnel face. After the first ring negative ring 5 is assembled in the shield tail, it is pushed backward as a whole by a jack until it is close to the reaction frame 4, and the pipe segment 21 and the reaction frame 4 are connected by bolts.

[0083] Step 8: After the shield machine is installed and debugged, the upper half of the simple steel sleeve can be installed. After the upper half of the simple steel sleeve is installed, adjust the clamping bolts and check the connection installation parts to ensure the integrity of the connection. At the connection between the upper and lower half of the steel sleeve, a water-swelling water stop strip is attached on the inside, and polyurethane is applied on the inside and outside to prevent leakage.

[0084] Step 9: Sealing the tail of the simple steel sleeve and the pipe segment 21. After the shield tail enters the steel sleeve, use the arc steel plate 20 to weld the end of the steel sleeve to the back arc surface of the pipe segment 21 with the -2 ring back-covering steel plate to ensure full welding; 15cm long D28mm steel bars can be added to the outside of the arc steel plate 20 as diagonal braces for reinforcement.

[0085] Step 10: The shield machine moves forward until the cutterhead panel is close to the edge of the reinforcement area, that is, the 0-ring segment 21 is assembled, and the second sand filling is carried out into the steel sleeve through the feed port at the top of the steel sleeve. This time, the filler fills the gap between the steel sleeve and the shield with sand. During the filling process, add water appropriately and discharge it through the drainage hole at the bottom of the steel sleeve to ensure the density of the sand.

[0086] At this stage, the shield machine continues to excavate and fill sand simultaneously until the 0-ring segment 21 is separated from the shield tail. In order to ensure that the segment 21 in the simple steel sleeve does not sink, the filler in the steel sleeve must be dense and uniform. During the filling process, it must be filled in multiple filling holes to ensure uniform distribution. The filling process is carried out in stages, and people are sent to observe the filling holes. When it is filled to a certain height, it needs to be leveled and dense. After leveling, continue to fill until the entire simple steel sleeve is completely filled.

[0087] Step 11: During the shield advancement process, wait for the shield tail to separate from the steel sleeve and use the shield machine's grouting pipe to simultaneously inject hardenable slurry to fill the gap.

[0088] When the cutterhead excavates to the +18 ring segment 21 and the assembly is completed, the machine should be stopped and the grouting holes of the segment 21 should be used to perform secondary grouting at the 0 ring, 2 ring, 4 ring, 6 ring, and 8 ring, respectively, with cement-water-glass double slurry. Pay attention to controlling the grouting pressure to avoid damaging the shield tail sealing measures, observe the grouting effect through the detection hole, and ensure that there is no water seepage, so as to facilitate the removal of the steel sleeve and the safety and reliability of the construction work surface of the hole ring closure.

[0089] Step 12: When the shield machine excavates to the 100th ring, the simple steel sleeve is removed. Before removal, the sealing condition of the tunnel door is checked through the detection hole to ensure that the grouting effect meets the requirements. According to the principle of "sealing as cutting", the arc steel plate 20 is welded with the backing steel plate of the +1 ring segment 21.

[0090] The key to the success of the present invention is to quickly and effectively assemble a simple short sleeve, close the shield starting space, quickly and effectively establish the stress balance of the soil bin, and actively take cement-based reinforcement measures to cut off the flow of water, which can effectively improve the safety of starting. The simple short sleeve includes main components such as an upper semicircular ring, a lower semicircular ring, and a transition ring. Various components are connected by components such as round flanges and bolts, and are waterproofed by components such as curtain rubber sheets and pressure plates. The steel, flanges, bolts, machinery used for round flange assembly, and cement-based reinforcement materials used for water-stopping partitions involved in the simple short sleeve of the present invention are all conventional materials or equipment, which can be dynamically optimized and adjusted as needed, and have strong operability. The shield starting space is extended by assembling, which solves the problem of no reinforcement space when the end well space is limited, such as near a river, close to buildings that cannot be demolished, and when pipelines cannot be relocated. The invention has many advantages of steel sleeve and cement system reinforcement. When the space is limited, a self-made simple short sleeve is used to extend the starting space, and the ground reinforcement improves the soil in the end range, actively cuts off the hydraulic connection, avoids water and sand gushing, and thus improves the starting safety. At the same time, it greatly reduces the unnecessary storage and transportation risks of the conventional steel sleeve method, reduces the project cost, shortens the construction period, has strong adaptability, and has obvious advantages. Therefore, the present invention has high economic and social benefits and has broad application prospects in the urban rail transit industry.

[0091] The content of the present invention is not limited to the embodiments listed, and any equivalent changes made to the technical solution of the present invention by ordinary technicians in this field after reading the description of the present invention are covered by the claims of the present invention.

Claims

1. A construction method for starting from the end of a shield machine under space-constrained conditions, characterized in that: The method comprises the following steps: Step 1: Carry out the reinforcement of mixing piles (9) according to the distribution of the end aquifer and the calculation of soil stability, and finally set a row of jet grouting piles (10) between the station enclosure structure and the reinforcement body of the mixing piles (9); Step 2: After the reinforcement is completed, determine the center line of the shield body at the wellhead of the shield machine, weld and install the transition ring (1) on the embedded ring plate of the station enclosure structure, and apply polyurethane to the outer side of the transition ring (1) and the embedded ring plate (2) to enhance waterproofing. If there is a large gap between the transition ring (1) and the embedded ring plate (2), fill the gap with steel plates and weld them again to make it firm; install the lower half of the simple short sleeve so that its center line coincides with the center line of the shield body, and connect the lower half of the ring with the transition ring (1) with bolts; Step 2: Install two 43 kg steel rails evenly distributed within a 60° arc below the installed simple short sleeve. The steel rails are laid from the rear end of the lower semicircular ring steel sleeve to the transition ring (1). The steel rails are fixed with a pressure plate, which is welded to the lower semicircular ring cylinder. According to the elevation of the shield machine, two guide rails are installed at the lower part of the tunnel portal, and a slope is made near the end of the shield machine. The height slope of the guide rail is consistent with that of the rail surface on the base. In order to ensure that the bottom sand layer provides sufficient anti-torsion friction reaction force for the shield machine, sand is laid between the two steel rails at the bottom of the steel sleeve and compacted. The height of the sand at each position is 15 mm higher than the height of the corresponding steel rail. After the shield machine is placed on it, it is further compacted. Step 3: Install the front shield and middle shield of the shield machine. Place them in the lower semicircular steel sleeve. After the front shield and middle shield are installed, ensure that there is a 50cm operating space between the front end of the front shield and the tail of the assembled simple short sleeve to facilitate the installation of the rubber curtain plate and the curtain pressure plate. Step 4: After the filler is installed in the inner guide rail of the lower semicircular ring of the steel sleeve, the upper semicircular ring (7) and the steel support (11) at the tail end of the steel sleeve are installed; the upper semicircular ring (7) at the tail end of the steel sleeve is connected to the lower semicircular ring of the steel sleeve by bolts, and the distance of 2.5 meters between the upper semicircular ring (7) at the tail end and the steel ring of the tunnel gate is supported and reinforced by 5 I-beams (6); Step 5: Install the initial water stop device at the rear of the steel sleeve, the water stop device includes a curtain rubber plate (14), a circular ring plate (18), bolts (16), nuts (19) and washers (17); the rear ring plate of the steel sleeve is reserved with 72 bolt holes; before installation, measure the position deviation of the screw holes, if the deviation is too large, the position of the holes on the curtain rubber plate (14) should be adjusted accordingly, and at the same time, clean the inner threads of the screw holes one by one, and evenly apply butter on the inner side; during installation, first install the curtain rubber plate (14), then the circular ring plate (18), the bolts (16) should be tightened as much as possible, so that the curtain rubber plate (14) is close to the steel sleeve, and then the circular ring plate (18) is turned into the steel sleeve; After the installation is completed, after the front shield of the shield machine is pushed into the steel sleeve by a jack, the arc-shaped steel plate (20) of the lower semicircle of the steel sleeve is welded, and pre-control measures are taken in advance; Step 6: After the rubber curtain plate is installed, use two 200T jacks to push the front shield and the middle shield into the steel sleeve. After they are in place, the upper I-beam (6) support can be removed; then hoist the cutterhead, install the shield machine body in the steel sleeve, and connect it with the connecting bridge and the rear supporting trolley; the guide rail inside the steel ring of the tunnel portal is 20cm long, and 60cm of space is reserved to ensure the rotation of the cutterhead and smooth debugging; after the debugging of the shield machine is completed, the upper half of the simple short sleeve can be installed; Step 7: After the steel sleeve and reaction frame (4) are installed and the shield machine is debugged, the negative ring (5) is installed and the shield machine is advanced forward until the cutterhead panel is close to the tunnel face but does not cut the tunnel face; after the first ring of negative ring (5) is assembled and formed in the shield tail, it is pushed backward as a whole by a jack until it is close to the reaction frame (4), and the pipe segment (21) and the reaction frame (4) are connected by bolts; Step 8: After the installation and commissioning of the shield machine is completed, the upper half of the simple short sleeve can be installed; after the upper half of the simple short sleeve is installed, adjust the tightening bolts and check the connection and installation parts to ensure the integrity of the connection; at the connection between the upper and lower semicircles of the steel sleeve, the inner side is affixed with a water-expandable water stop strip, and the inner and outer sides are coated with polyurethane to prevent leakage; Step 9: Sealing the tail of the simple short sleeve and the pipe segment (21); after the shield tail enters the steel sleeve, the end of the steel sleeve is welded to the back arc surface of the pipe segment (21) with a -2 ring back-covering steel plate using an arc steel plate (20) to ensure full welding; a 15cm long D28mm steel bar is added to the outside of the arc steel plate (20) as a diagonal brace for reinforcement; Step 10: The shield machine is advanced forward until the cutterhead panel is close to the edge of the reinforcement area, i.e., the 0-ring segment (21) is assembled, and the steel sleeve is filled with sand for the second time through the feed port at the upper part of the steel sleeve. The sand is filled in the gap between the steel sleeve and the shield machine. During the filling process, water is added appropriately and discharged through the drainage hole at the lower part of the steel sleeve to ensure the density of the sand. During this stage, the shield machine continues to advance and sand filling is carried out simultaneously until the 0-ring segment (21) is separated from the shield tail; in order to ensure that the segment (21) in the simple short sleeve does not sink, the filler in the steel sleeve must be dense and uniform. During the filling process, it is necessary to fill in multiple filling holes separately to ensure uniform distribution. The filling process is carried out in stages, and a person is sent to observe the filling hole. When the filling reaches a certain height, it is necessary to level and compact it. After leveling, continue to fill until the entire simple short sleeve is completely filled; Step 11: During the shield advancement process, when the shield tail is separated from the steel sleeve, the hardenable slurry is injected synchronously through the grouting pipe of the shield machine to fill the gap; When the cutterhead excavates to the +18th ring segment (21) and the assembly is completed, the machine should be stopped and secondary grouting is performed at the 0th ring, 2nd ring, 4th ring, 6th ring and 8th ring respectively using the grouting holes of the segment (21), injecting cement-water-glass double liquid grout; Step 12: When the shield machine excavates to the 100th ring, the simple short sleeve is removed; before removal, the sealing condition of the tunnel door is checked through the detection hole to ensure that the grouting effect meets the requirements; according to the principle of "sealing as cutting", the arc steel plate (20) is welded with the backing steel plate of the +1 ring segment (21); The construction structure initiated at the end of the shield machine under space-constrained conditions constructed according to the construction method includes a cement reinforcement system and a simple short sleeve; The cement reinforcement system comprises a mixing pile (9), and the inner side of the mixing pile (9) is a jet grouting pile (10); The simple steel sleeve is located inside the jet grouting pile (10) and arranged longitudinally, and comprises a transition ring (1) connected to the jet grouting pile (10), wherein the upper inner portion of the transition ring (1) is sequentially composed of a middle upper semicircular ring (28) and a tail upper semicircular ring (7), and the lower inner portion is sequentially composed of a tail lower semicircular ring (8) and a middle lower semicircular ring (29); The inner side of the jet grouting pile (10) is provided with a pre-buried ring plate (2), and the transition ring (1) is welded and fixed to the pre-buried ring plate (2); The middle upper semicircular ring (28) is connected and fixed to the transition ring (1) by a longitudinal steel support (11); An initial water-stop device is arranged between the transition ring (1) and the embedded ring plate (2), and the initial water-stop device comprises a gasket (17) and a sector-shaped circular ring plate (18), which is fixed to the embedded ring plate (2) by bolts (16) and nuts (19), a cord rubber plate (14) is arranged between the gasket (17) and the embedded ring plate (2), and a flap (15) is hinged on the circular ring plate (18).

2. The construction method of shield tunneling starting from the end under space-constrained conditions according to claim 1 is characterized in that: The middle upper semicircular ring (28) and the tail upper semicircular ring (7), and the middle upper semicircular ring (28) and the transition ring (1) are connected and fixed by flanges and bolts arranged at the joint surfaces, and a rubber pad is sandwiched in between; The tail end lower semicircular ring (8) and the middle lower semicircular ring (29), and the tail end lower semicircular ring (8) and the transition ring (1) are connected and fixed by flanges and bolts arranged at the joint surfaces, and a rubber pad is sandwiched in between.

3. The construction method of shield tunneling starting from the end under space-constrained conditions according to claim 2 is characterized in that: The middle upper semicircular ring (28) and the tail upper semicircular ring (7) form an upper semicircular ring cylinder, the tail lower semicircular ring (8) and the middle lower semicircular ring (29) form a lower semicircular ring cylinder, and the upper semicircular ring cylinder and the lower semicircular ring cylinder are fixed by bolt connection.

4. The construction method of shield tunneling starting from the end under space-constrained conditions according to claim 3 is characterized in that: The semicircular ring comprises two circumferential end plates (23), a transverse bottom plate and a longitudinal rib plate (24) are arranged between the end plates (23), and a longitudinal bolt hole (25) is arranged on the bottom plate; The semicircular ring is divided into multiple sections, and the ribs (24) at the end surface of each section are provided with an annular bolt connection (26).

5. The construction method of shield tunneling starting from the end under space-constrained conditions according to claim 4 is characterized in that: The bottom of the lower semicircular cylinder is supported by a base (12).

6. The construction method of shield tunneling starting from the end under space-constrained conditions according to claim 5, characterized in that: The inner bottom surface of the simple short sleeve is provided with two tracks which are connected to the guide rail outwards.

Images