Interval air shaft construction method based on vertical jacking process

Abstract

The invention relates to an interval air shaft building method based on a vertical jacking process, which comprises the following steps: constructing an interval tunnel, adopting a special ring for a lining corresponding to a vertical shaft, and adopting a common ring for the rest; a shallow foundation pit is excavated, an air shaft is constructed in the shallow foundation pit, and a hole is reserved in the air shaft; a jacking support is manufactured, and a door-shaped jacking platform is arranged at the top of the jacking support; the vertical shaft pipe joints are placed on the jacking support and are jacked out from the middle of the jacking platform one by one in sequence till being jacked out from the reserved hole; a rotary cutting device is mounted at the top of the jacked first vertical shaft pipe joint and is used for upwards and rotatably cutting a lining structure and rock soil; and a hole opening ring beam and a special-shaped ring beam are respectively constructed at upper and lower interface parts of the vertical shaft. According to the method, the tunnel is excavated firstly, then the shallow foundation pit and the air shaft main body structure are constructed, and finally the vertical jacking process is adopted to form the connecting channel, so that the vertical dumbbell-shaped air shaft structure is formed, the problem that the space surplus of the air shaft is large is avoided, the engineering implementation risk is reduced, and the economic benefit and the social benefit are remarkable.

Description

Technical Field

[0001] The present invention relates to the technical field of underground engineering construction, and particularly relates to a construction method for an interval ventilation shaft based on a vertical jacking process. Background Art

[0002] At present, with the development of urban rail transit tunnel engineering towards greater burial depths and longer intervals, long buried-depth interval tunnels are becoming more and more common. It is particularly important to set up interval ventilation shafts for long buried-depth interval tunnels.

[0003] If the interval ventilation shaft of a long buried-depth interval tunnel is constructed according to the conventional construction method, it is necessary to first construct a deep large foundation pit (shaft), and then carry out shield tunneling in and out of the hole. Both the deep large foundation pit (shaft) and the shield tunneling in and out of the hole are typical high-risk operations of the first level. Especially in soft soil areas or areas near rivers, lakes and seas, the implementation risks will increase exponentially. At the same time, the construction period and implementation cost will also increase accordingly.

[0004] Considering that the space size requirements for interval ventilation shaft ventilation are not high, there is currently a large amount of surplus ventilation space based on deep large shafts, and there is much room for optimization. Therefore, it is necessary to adopt new processes and construction methods to optimize the ventilation shaft structure and the overall construction method. Summary of the Invention

[0005] The purpose of the present invention is to provide a construction method for an interval ventilation shaft based on a vertical jacking process to solve the problems existing in the existing methods, such as high operation risks, high construction costs, and large surplus space.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] Provide a construction method for an interval ventilation shaft based on a vertical jacking process, the method comprising:

[0008] Adopt the mined tunneling method or the shield tunneling method to construct the interval tunnel, and use special rings for the lining structure of the interval tunnel corresponding to the shaft position range, and use ordinary rings for the lining structure of the interval tunnel in other position ranges;

[0009] Excavate a shallow foundation pit from the ground surface, construct the main structure of the ventilation shaft in the shallow foundation pit, and set a reserved hole at the position corresponding to the shaft in the ventilation shaft;

[0010] Manufacture an M-shaped jacking support, fix it to the inner bottom of the interval tunnel, face upwards corresponding to the shaft, and set a portal-shaped jacking platform at the top of the jacking support;

[0011] Place the prefabricated shaft pipe sections on the jacking support one by one and successively jack them out upwards from the middle of the jacking platform until they are jacked out from the reserved hole, and end the vertical jacking operation of the shaft; a rotary cutting device is installed at the top of the first shaft pipe section to be jacked to rotate and cut the lining structure and rock and soil upwards;

[0012] At the upper and lower interface parts of the vertical shaft, a portal ring beam and a special-shaped ring beam are constructed respectively.

[0013] Furthermore, the special segment is a steel pipe segment, a steel-concrete composite pipe segment or a fiber composite material reinforced lining pipe segment; among them, in the tunnel vault area corresponding to the jacking position of the vertical shaft, a fiber concrete pipe segment lining is adopted to reserve conditions for direct jacking cutting.

[0014] The ordinary segment is a reinforced concrete lining pipe segment.

[0015] Furthermore, the ventilation shaft includes a ventilation shaft roof, ventilation shaft side walls and a ventilation shaft floor. An above-ground structure extending upward to the ground surface is arranged on the ventilation shaft roof, and a reserved hole is arranged on the ventilation shaft floor.

[0016] Furthermore, the jacking support includes an M-shaped support. The transverse sides of the M-shaped support have arc-shaped panels, and a vertical support is arranged at the middle position of the M-shaped support.

[0017] The bottom of the jacking support is fixed on the invert of the interval tunnel through the arc-shaped panels on the transverse sides and the fulcrums at the bottom of the middle position of the M-shaped support. The top of the jacking support supports the jacking platform through the vertical support and the fulcrums on both sides of the top of the M-shaped support.

[0018] Furthermore, a jack is arranged at the top of the jacking support, and the vertical shaft segment is jacked upward through the jack.

[0019] Furthermore, the jacking platform includes columns and a horizontal top frame at the top of the columns. An opening is arranged at the center of the horizontal top frame.

[0020] Furthermore, a backstop device is arranged at the opening at the top of the jacking platform. The backstop device is a hoop. When the vertical shaft segment starts to be jacked upward and completes the jacking operation for one segment length, the vertical shaft segment is temporarily fixed through the backstop device. Before the subsequent vertical shaft segment below starts to be jacked upward, the backstop device is opened and the upward jacking operation is continued. Such a cycle is repeated until all the jacking operations are completed.

[0021] Furthermore, a water stop device is arranged at the contact part between the vertical shaft segment and the top of the interval tunnel.

[0022] Furthermore, the vertical shaft segment is jacked out 1-2 rings from the reserved hole. After the vertical jacking operation of the vertical shaft is completed, the vertical shaft segment higher than the ventilation shaft floor is cut off. Subsequently, the portal ring beam is constructed, and a special-shaped ring beam is constructed at the connection part between the interval tunnel and the vertical shaft.

[0023] Furthermore, grouting pipes are pre-buried in advance at the upper and lower interface parts of the vertical shaft. After the vertical jacking operation of the vertical shaft is completed, the outer strata are grouted and reinforced by using the grouting pipes for micro-disturbance grouting to form a strata reinforcement area, so as to reserve conditions for the casting of the post-cast ring beam.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] The present invention provides a construction method for an interval air shaft based on the vertical jacking process. First, the tunnel is excavated, then the shallow foundation pit and the main structure of the air shaft are constructed (which can also be implemented synchronously with the lower tunnel), and finally, the vertical jacking process is used to form a connecting passage, thus forming a vertical "dumbbell-shaped" air shaft structure. This can effectively avoid the problem of a large amount of surplus space in the air shaft caused by conventional construction methods. Especially when the buried depth of the interval tunnel is large, the connecting passage (shaft) formed by the vertical jacking process effectively connects the rail transit tunnel with the small foundation pit (air shaft) above. This not only meets the requirements of interval tunnel ventilation and safe operation, but also shortens the construction period, saves investment, and reduces the engineering implementation risk. It can meet the rapid construction needs of long subway tunnels and shafts, with significant economic and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0027] Figure 1 It is a cross-sectional layout drawing of the interval tunnel, shaft and shallow foundation pit in the present invention.

[0028] Figure 2 It is a cross-sectional layout drawing of the interval tunnel and the air shaft in the present invention.

[0029] Figure 3 It is a schematic diagram of shaft jacking in the present invention.

[0030] Figure 4 It is a plan layout drawing of the interval tunnel and the air shaft in the present invention.

[0031] The labels in the figures are as follows:

[0032] 1 - Interval tunnel, 2 - Shaft, 3 - Shallow foundation pit, 4 - Air shaft, 5 - Ground surface;

[0033] 11 - Special ring, 12 - Ordinary ring, 13 - Special-shaped ring beam;

[0034] 21 - Shaft side wall, 22 - Shaft top, 23 - Jacking support, 24 - Jacking platform, 25 - Anti-retreat device, 26 - Water stop device, 27 - Grouting pipe, 28 - Stratum reinforcement area, 29 - Shaft pipe section, 210 - Rotary cutting device, 211 - Jack;

[0035] 31 - Foundation pit side wall, 32 - Foundation pit bottom;

[0036] 41 - Wind well roof, 42 - Wind well side wall, 43 - Wind well floor, 44 - Structure above ground, 45 - Reserved hole, 46 - Ring beam of the hole. Detailed implementation mode

[0037] To facilitate the understanding of the present invention, the present invention will be described more comprehensively below with reference to the relevant drawings. The preferred embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0038] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0039] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "connection", "installation", etc. should be understood in a broad sense. For example, it can be fixedly connected and installed, or detachably connected and installed, or integrally connected and installed. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0040] It should also be noted that although the step sequence is involved in the method description, in some cases, it can be executed in a different order from here and should not be construed as a limitation of the step sequence.

[0041] In the detailed implementation mode, the height direction of the vertical shaft 2 is the "vertical" perpendicular to the horizontal plane, and the "perpendicular" is also the "vertical".

[0042] To overcome the problems of high operation risk, high construction cost, and large space surplus in the current interval wind well, the present invention provides a method for constructing an interval wind well based on the vertical jacking process. The method specifically includes the following steps:

[0043] S1: Carry out the construction of the shield tunnel.

[0044] The construction of the interval tunnel 1 is carried out by the mined tunneling method (or shield tunneling method). For the lining structure of the interval tunnel 1 within the position range corresponding to the shaft 2, special rings 11 are adopted, and for the lining structure of the interval tunnel 1 in other position ranges, ordinary rings 12 are adopted. The interval tunnel 1 is constructed according to the design requirements. Generally, the mined tunneling method (or shield tunneling method) is considered for implementation. According to the contour ranges of the shaft 2 and the ventilation shaft 4 above, the interval tunnel 1 is divided into a special ring area and an ordinary ring area in advance.

[0045] Among them:

[0046] In the special ring area, special rings 11 are adopted, and the segment linings are steel segment linings, steel-concrete composite segment linings or fiber composite material reinforced lining segment linings. Among them, for the tunnel crown area corresponding to the jacking position of the shaft 2, fiber concrete segment linings are adopted to reserve conditions for direct jacking cutting.

[0047] In the ordinary ring area, ordinary rings 12 are adopted, and the segment linings are conventional reinforced concrete lining segment linings.

[0048] In addition, on both sides of the vertical jacking construction range, steel sealing doors are set for temporary closure in case of emergency.

[0049] S2: Carry out the construction of pouring the shallow foundation pit below the ground surface and the main structure of the upper ventilation shaft.

[0050] S201: Excavate the shallow foundation pit 3 from the ground surface 5.

[0051] According to the contour range of the ventilation shaft 4, carry out the construction of the retaining structure, advance the construction dewatering, and then carry out the excavation construction of the shallow foundation pit 3. According to the requirements of controlling the ground surface settlement and the construction sequence requirements, based on the principle of supporting while excavating, timely carry out the construction of the foundation pit support structure (such as steel pipe internal support) to ensure the stability of the shallow foundation pit 3. When excavating to 0.5 - 1.0 m above the bottom 32 of the shallow foundation pit 3, manual excavation is adopted to avoid over-excavation.

[0052] S202: Pour the main structure of the ventilation shaft 4 in the foundation pit 3, and set a reserved hole 45 at the position corresponding to the shaft 2 in the ventilation shaft 4.

[0053] According to the principle from bottom to top, timely construct the bottom slab 43, side wall 42 and top slab 41 of the ventilation shaft, as well as the structure 44 of the upper ventilation shaft emerging from the ground surface, and reserve a hole 45 at the position of the lower shaft 2. The reserved hole 45 is temporarily sealed with plain concrete (or glass fiber reinforced bars). Finally, carry out the backfilling operation above the top slab 41 of the ventilation shaft.

[0054] S3: According to the design requirements, fabricate the M-shaped jacking support 23 with steel structure in the factory in advance, fix it to the inner bottom of the interval tunnel 1, strictly corresponding to the shaft 2, and set a gantry-shaped jacking platform 24 at the top of the jacking support 23.

[0055] Among them:

[0056] The jacking support 23 includes an M-shaped support. The transverse sides of the M-shaped support have arc-shaped panels, and a vertical support is provided at the middle position of the M-shaped support. The bottom of the jacking support 23 is fixed on the inverted arch of the interval tunnel 1 through the arc-shaped panels on the transverse sides and the fulcrums at the bottom of the middle position of the M-shaped support. The fulcrum at the bottom of the middle position is aligned with the bottom of the tunnel arch, and the arc-shaped panels on both sides are aligned with the inner contour of the tunnel lining. Specifically, shear-resistant anchor bolts can be used for connection and fixation. The top of the jacking support 23 supports the jacking platform 24 through the vertical support and the fulcrums on both sides of the top of the M-shaped support. A jack 211 is provided at the top of the jacking support 23, and the shaft pipe section 29 is jacked upward through the jack 211.

[0057] The jacking platform 24 includes columns and a horizontal top frame at the top of the columns. It adopts a steel plate and concrete composite structure. An opening is provided at the center of the horizontal top frame, which is on the same vertical line as the jacking support 23 and the bottom of the tunnel arch.

[0058] S4: Place the prefabricated shaft pipe section 29 on the jacking support 23 in advance, and successively jack it out from the middle of the jacking platform 24 one by one until it is jacked out from the reserved hole 45, thus ending the vertical jacking operation of the shaft 2.

[0059] A rotary cutting device 210 is installed at the top of the first jacked shaft pipe section 29, which is used to rotary cut the lining structure and geotechnical materials upward. The top of the rotary cutting device 210 has rotary cutting blades, and it has a box body and a slag discharge structure. Existing equipment can be used, and the present invention does not make improvements to it.

[0060] A backstop device 25 is provided at the opening at the top of the jacking platform 24. The backstop device 25 is in the form of a hoop. When the shaft pipe section 25 starts to be jacked upward and completes the jacking operation for one pipe section length, the shaft pipe section 25 is temporarily fixed through the backstop device 25, effectively suppressing its downward displacement trend under the action of gravity. Before the subsequent shaft pipe section 25 below starts to be jacked upward, open the backstop device 25 and continue the upward jacking operation. Repeat this cycle until all jacking operations are completed.

[0061] A water stop device 26 is provided in advance at the contact part between the shaft pipe section 29 and the top of the interval tunnel 1. The water stop device 26 can adopt a curtain rubber water stop device or an air cushion type water stop device according to the situation.

[0062] According to the construction sequence, place the shaft pipe section 29 above the jacking support 23. Through the supporting action of the jacking platform 24, use the jacking equipment to successively jack out the shaft pipe section 29 from the middle of the jacking platform 24 and the backstop device 25. To prevent the local crushing of the shaft pipe section 29, a flexible joint, such as an ethylene propylene diene monomer (EPDM) gasket, is provided at the end of the shaft pipe section 29.

[0063] The shaft segment 29 is gradually jacked out from the reserved hole 45 in the shaft bottom slab 43 until the top of the air shaft 22 is lifted to a height of 1 - 2 ring heights of the shaft segment 29 above the shaft bottom slab 43, and then the vertical jacking operation of the shaft 2 ends.

[0064] S5: Interface construction and connection to the air shaft.

[0065] According to the formation properties at the interface parts of the upper and lower ends of the shaft 2 and the external water and soil pressure conditions, when necessary, grouting pipes 27 are pre-embedded at the upper and lower interface parts of the shaft 2 in advance. After the vertical jacking operation of the shaft 2 ends, the outside formation is grouted and reinforced with micro-disturbance to form a formation reinforcement area 28.

[0066] The shaft segment 29 is jacked out 1 - 2 rings from the reserved hole 45. After the formation reinforcement indexes (mainly the formation permeability coefficient and the unconfined compressive strength) meet the design requirements, according to the requirements of the construction sequence, when the vertical jacking operation of the shaft 2 ends, the shaft segment 29 that is higher than the shaft bottom slab 43 is cut off. Subsequently, according to the spatial position of the ring beam, local formation excavation, steel bar binding and the casting of the hole ring beam 46 are carried out. Finally, a special-shaped ring beam 13 is constructed at the connection part between the interval tunnel 1 and the shaft 2, which is in the shape of a knife handle.

[0067] The shaft segment 29 effectively connects the lower tunnel and the upper air shaft 4 structure, forming a "dumbbell-shaped" air shaft structure system. Specifically:

[0068] Such as Figure 1 and Figure 2 , the said system includes the interval tunnel 1, the air shaft 4 and the vertical shaft 2 for upper and lower connection. The scope of the tunnel lining structure includes the special ring 11 and the ordinary ring 12. The tunnel lining within the influence range of the vertical jacking construction of the shaft 2 adopts the special ring 11, and generally steel pipe segments (or steel-concrete composite pipe segments) can be considered. There is a sufficient vertical safety distance between the interval tunnel 1 and the upper shallow foundation pit 3, which can ensure that the construction of the tunnel and the shallow foundation pit 3 are basically independent of each other and do not interfere with each other. After the shallow foundation pit 3 is constructed, the main structure is constructed in time according to the design requirements, that is, the air shaft top slab 41, the air shaft side wall 42, the air shaft bottom slab 43 and the above-ground structure 44, forming the basic outline of the air shaft 4, and reserved holes 45 are set at specific positions. The contour size of the holes must strictly correspond to the position and size of the shaft segment 29 to reserve conditions for the connection and vertical jacking construction of the shaft 2. Considering the action of the outside formation water and soil pressure and the risk control requirements during the vertical jacking construction of the shaft 2, therefore, the vertical jacking construction of the shaft 2 generally needs to be carried out after the main structure of the upper air shaft 4 is completed, and tunnel closing measures (such as temporary blocking doors, generally made of steel structure) are set in advance on both sides of the jacking position. At the same time, the top 22 of the shaft generally should be higher than the bottom of the foundation pit 32 by a certain distance, generally considered as the height of 1 - 2 ring pipe segments.

[0069] Such as Figure 2As shown in the figure, post-cast ring beams are provided at the connections between the side wall 21 of the shaft and the lower tunnel 1 and the upper air shaft 4. Among them, the lower ring beam is a "knife handle type" special-shaped ring beam 13, which are all to be implemented after the jacking of the shaft pipe section 29 is completed. Waterstop and sealing measures should also be set at the position of the post-cast ring beam. Generally, water-swelling rubber can be considered and grouting pipes can be embedded for treatment. At the same time, according to the magnitude of the underground water and soil pressure, when necessary, before the construction of the post-cast ring beam, the ground within a certain range outside is grouted and reinforced using the grouting pipe 27 at the corresponding position to form a ground reinforcement area 28 that completely wraps the position of the ring beam.

[0070] As Figure 2 and Figure 4 shown, the interval tunnel 1 and the shaft 2 are generally located in the middle position of the air shaft 4.

[0071] As Figure 3 shown, the jacking construction of the shaft 2 must be equipped with corresponding working platforms and jacking equipment. Among them, the jacking support 23 is located at the invert part of the tunnel 1 and is mechanically connected to the tunnel lining 11 using a special "M" type structure. The jacking platform 24 is located above the jacking support 23, and the two can be fixed in a combination of welding and mechanical connection. The anti-retreat device 25 is located above the jacking platform 24, mainly to hoop and vertically limit the jacked pipe section to ensure that the pipe section can only move upward unidirectionally and cannot move downward. Before the jacking construction, a waterstop device 26 must be set at the connection between the pipe section and the special lining at the top of the tunnel. The waterstop device 26 can generally adopt measures such as curtain rubber waterstop or air-cushion type waterstop according to the magnitude of the formation water pressure at the corresponding position. At the same time, in order to avoid local damage to the pipe section caused by excessive vertical jacking force, a flexible joint is set between the pipe sections, such as an ethylene propylene diene monomer (EPDM) gasket.

[0072] The core of the implementation method of the above-mentioned "dumbbell-shaped" air shaft is the shaft 2 formed based on vertical jacking and its connection technology with the upper and lower structures. The in-tunnel vertical jacking technology is relatively mature. However, due to the influence of the external formation water and soil pressure, the shield tunnel 1 within the influence range of the vertical jacking load needs to adopt a special ring 11, and emergency doors should be prepared at a certain distance on both sides of the action area. Both can be made of Q235 steel or a steel-concrete composite structure. At the same time, post-cast ring beams need to be constructed at the connection parts between the shaft 2 and the upper air shaft floor 43 and the lower tunnel. The pouring of the upper opening ring beam 46 can be completed inside the air shaft 4, which belongs to a conventional process. However, the pouring of the lower special-shaped ring beam 13 needs to be completed inside the tunnel, which is an unconventional process from bottom to top. Not only do we need to set up a support platform and grout and reinforce the outside formation in advance, but also pour it with self-leveling micro-expansion concrete (≥C35) and embed grouting pipes to reserve the later supplementary grouting measures.

[0073] In the above structural system, the tunnel is generally constructed by the cut-and-cover method (or the shield method). For the special segment 11 of the segment lining, steel segment or steel-concrete composite segment is generally considered, and the ordinary segment 12 is a conventional reinforced concrete segment; the shallow foundation pit 3 is constructed by the conventional open-cut method. The side wall 31 of the foundation pit can adopt interval bored piles or diaphragm walls according to the situation, and internal supports can be set according to the requirements of controlling the deformation of the surrounding strata. The bottom slab of the foundation pit is treated with plain concrete for sealing; the pipe sections of the shaft 2 can consider conventional reinforced concrete pipe sections, and flexible joints are set between the pipe sections, which can not only do waterproofing but also meet the need for spreading the jacking load; the related structures of the ventilation shaft 4 are all of conventional reinforced concrete structures; the post-cast ring beams set at the connecting parts of the shaft 2 with the upper ventilation shaft bottom slab 43 and the lower tunnel 1 are all of conventional reinforced concrete structures. The concrete involved in the above components shall all adopt waterproof concrete not lower than C35, the steel bars can adopt ordinary HRB335 and above grades, and the stirrups can adopt HPB300 steel bars.

[0074] In the implementation process of the method provided by the present invention, the following points need to be noted:

[0075] 1. The position of the shaft 2 needs to be measured and calibrated in advance, and it should be strictly aligned with the reserved hole 45 positions of the upper shallow foundation pit 3 and the ventilation shaft bottom slab 43. Generally, the size of the reserved hole 45 is slightly larger than the ventilation shaft pipe section, and the specific accuracy deviation should be controlled within 5-10 mm;

[0076] 2. The tunnel lining is mainly divided into the special segment 11 and the ordinary segment 12. The special segment 11 is mainly to meet the need of vertical jacking. Generally, it can be made of steel segment or steel-concrete composite segment, which can provide greater toughness and bear greater impact force;

[0077] 3. The vertical distance between the tunnel and the upper ventilation shaft 4 is generally determined to be not less than one times the tunnel diameter, and it can be flexibly adjusted according to the tunnel burial depth. Under the condition of meeting the use space of the ventilation shaft 2, the greater the vertical distance between the two, the higher the economic benefit;

[0078] 4. When carrying out vertical jacking operation in the formed tunnel, one of the most critical processes is the reliability of the water stop device 26 at the crown part of the tunnel. Air cushion type or extended steel ring type water stop measures with more reliable performance can be adopted if necessary according to the situation.

[0079] The structure of the present invention has the following characteristics and advantages:

[0080] 1) Based on the "dumbbell-shaped" interval ventilation shaft, compared with the conventional rectangular ventilation shaft structure based on deep and large shaft foundation pits, the "dumbbell-shaped" ventilation shaft structure effectively reduces the redundant space, can save the construction period to the greatest extent, reduce the project implementation cost, and the greater the tunnel burial depth at the ventilation shaft position, the better the economic benefit, providing a new idea for deep underground space construction;

[0081] 2) The "dumbbell-shaped" interval air shaft structure proposed by the present invention uses a later-built vertical shaft to connect the previously constructed tunnel and the small foundation pit air shaft above, changing the conventional construction process, fundamentally avoiding the three major primary risk source operations faced by the previous construction of deep and large foundation pit (vertical shaft) structures and then the shield tunneling in and out of the hole, effectively reducing the project risk and improving the project quality;

[0082] 3) The "dumbbell-shaped" interval air shaft structure system described in the present invention can meet the ventilation and operation safety needs of long tunnel sections. The scheme has clear ideas, simple technology and convenient construction, and has high economic and social benefits, and has a wide application prospect in structural engineering involved in urban underground space development, rail transit, railway projects, etc.

[0083] The above uses specific examples to elaborate on the present invention, which is only used to help understand the present invention and is not intended to limit the present invention. For those skilled in the technical field to which the present invention pertains, according to the idea of the present invention, several simple deductions, deformations or substitutions can also be made.

Claims

1. Construction method of interval air shaft based on vertical jacking process, characterized in that: The method includes: Using the mined tunneling method or shield tunneling method to construct the interval tunnel (1), the lining structure of the interval tunnel (1) in the position range corresponding to the shaft (2) adopts a special ring (11), and the lining structure of the interval tunnel (1) in other position ranges adopts a common ring (12); Excavate a shallow foundation pit (3) from the ground surface (5), construct the main structure of the air shaft (4) in the shallow foundation pit (3), and set a reserved hole (45) at the position corresponding to the shaft (2) in the air shaft (4); Manufacture an M-shaped jacking support (23), fix it to the bottom inside the interval tunnel (1), face upward corresponding to the shaft (2), and set a portal-shaped jacking platform (24) at the top of the jacking support (23); Place the prefabricated shaft segment (29) on the jacking support (23), and successively jack it upward one by one from the middle of the jacking platform (24) until it is jacked out from the reserved hole (45) to end the vertical jacking operation of the shaft (2); A rotary cutting device (210) is installed at the top of the first jacked shaft segment (29) for upward rotary cutting of the lining structure and rock and soil; Construct a portal ring beam (46) and a special-shaped ring beam (13) at the upper and lower interface parts of the shaft (2) respectively.

2. A construction method of interval air shaft based on vertical jacking process according to claim 1, characterized in that: The special ring (11) is a steel segment, a steel-concrete combined segment or a fiber composite material reinforced lining segment; among them, the tunnel arch crown area corresponding to the jacking position of the shaft (2) adopts a fiber concrete segment lining to reserve conditions for direct jacking and cutting; The common ring (12) is a reinforced concrete lining segment.

3. A construction method of interval air shaft based on vertical jacking process according to claim 2, characterized in that: The air shaft (4) includes an air shaft roof (41), air shaft side walls (42) and an air shaft bottom plate (43). An above-ground structure (44) extending upward to the ground surface (5) is provided on the air shaft roof (41), and the reserved hole (45) is provided on the air shaft bottom plate (43).

4. A construction method of interval air shaft based on vertical jacking process according to claim 3, characterized in that: The jacking support (23) includes an M-shaped support. The lateral sides of the M-shaped support have arc-shaped panels, and a vertical support is provided at the middle position of the M-shaped support; The bottom of the jacking support (23) is fixed on the invert of the interval tunnel (1) through the arc-shaped panels on the lateral sides and the fulcrums at the bottom of the middle position of the M-shaped support. The top of the jacking support (23) supports the jacking platform (24) through the vertical support and the fulcrums on both sides of the top of the M-shaped support.

5. A construction method of interval air shaft based on vertical jacking process according to claim 4, characterized in that: A jack (211) is provided at the top of the jacking support (23), and the shaft segment (29) is jacked upward through the jack (211).

6. A construction method of interval air shaft based on vertical jacking process according to claim 5, characterized in that: The jacking platform (24) includes columns and a horizontal top frame at the top of the columns. An opening is provided at the center of the horizontal top frame.

7. A construction method for an interval air shaft based on the vertical jacking process according to claim 6, characterized in that: A backstop device (25) is provided at the opening on the top of the jacking platform (24). The backstop device (25) is a hoop. When the shaft pipe section (29) starts to be jacked upward and completes the jacking operation for the length of one pipe section, the shaft pipe section (29) is temporarily fixed by the backstop device (25). Before the subsequent shaft pipe section (29) below starts the upward jacking operation, the backstop device (25) is opened and the upward jacking operation continues. This cycle is repeated until all the jacking operations are completed.

8. A construction method for an interval air shaft based on the vertical jacking process according to claim 7, characterized in that: A water stop device (26) is provided at the contact part between the shaft pipe section (29) and the top of the interval tunnel (1).

9. A construction method for an interval air shaft based on the vertical jacking process according to claim 8, characterized in that: The shaft pipe section (29) is jacked out of the reserved hole (45) by 1 - 2 rings. After the vertical jacking operation of the shaft (2) is completed, the shaft pipe section (29) that is higher than the air shaft floor (43) is cut off. Subsequently, the portal ring beam (46) is constructed, and the special-shaped ring beam (13) is constructed at the connection part between the interval tunnel (1) and the shaft (2).

10. A construction method for an interval air shaft based on the vertical jacking process according to claim 9, characterized in that: Grouting pipes (27) are pre-embedded in advance at the upper and lower interface parts of the shaft (2). After the vertical jacking operation of the shaft (2) is completed, the outer formation is grouted and reinforced by means of micro-disturbance using the grouting pipes (27) to form a formation reinforcement area (28), creating conditions for the casting of the post-cast ring beam.

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