Receiving construction method of rectangular jacking pipe in station main body enclosure stage

Abstract

The invention relates to the technical field of pipe jacking construction, in particular to a receiving construction method of a rectangular pipe jacking in a station main body enclosure stage, the pipe jacking construction stage is advanced to the station main body enclosure stage, it is not needed to wait for long station main body construction completion, and the overall construction period of a subway station can be greatly shortened; the rectangular pipe jacking machine is received through the reserved pipe jacking receiving platform when the foundation pit is excavated, input of manpower and material resources for additionally building the pipe jacking receiving platform is omitted, and waste is avoided; non-uniform stress of the enclosure underground continuous wall in the pipe jacking construction process is balanced through supporting axial force of the first additional supporting units, the temporary ring frame beams have good torsion resistance and mechanical transmission performance, and the stability of a supporting system is enhanced.

Description

Technical Field

[0001] The invention relates to the technical field of jacking pipe construction, in particular to a receiving construction method of a rectangular jacking pipe in a station main body enclosure stage. Background Art

[0002] The rectangular pipe jacking machine is a large machine used for excavation in the soil. Compared with the open-cut tunnel, the advantage of the pipe jacking tunnel is that the jacking tunneling has less disturbance to the surrounding soil and the construction speed is faster. Therefore, the pipe jacking machine is widely used in underground projects. When building a subway station, the structure of the subway station is generally excavated by the open-cut method. The open-cut excavation requires the isolation of the site within the construction range. However, when there are dense human activities around the subway station and there are many buildings, there will be a situation where the foundation pit of the auxiliary structure cannot be constructed by the open-cut method. At this time, it is very appropriate to use a rectangular pipe jacking machine to excavate the auxiliary structure channel.

[0003] However, there are generally two construction methods for excavating auxiliary structure channels using rectangular pipe jacking machines in the prior art: the first construction method is to wait for the completion of the main construction of the station before carrying out pipe jacking construction, which will have the following technical problems: first, the main construction period of the station is long, and the waiting time of the rectangular pipe jacking machine will seriously slow down the construction progress and extend the construction period; second, it is necessary to build an additional pipe jacking receiving platform in the station body to receive the rectangular pipe jacking machine, which wastes manpower and material resources. Another construction method is to carry out pipe jacking construction during the station body enclosure stage, but at this time, the force of the underground continuous wall is very complex, and the support system is frequently switched. During the pipe jacking construction process, the uneven stratum can easily cause the support system to become unstable and twist, resulting in safety issues such as water leakage, cracking, and instability of the foundation pit.

[0004] In view of this, it is necessary to propose a receiving construction method for rectangular jacking pipes during the station main enclosure stage to solve or at least alleviate the above defects. Summary of the invention

[0005] The main purpose of the present invention is to provide a receiving construction method for a rectangular jacking pipe in the station main enclosure stage, so as to solve the technical problems in the prior art of long jacking pipe construction period, waste of manpower and material resources and easy instability of the supporting system.

[0006] To achieve the above object, the present invention provides a receiving construction method of a rectangular jacking pipe in the station main body enclosure stage, comprising the following steps: S1. After the construction of the underground continuous wall of the station body is completed, a foundation pit is excavated downward along the inner wall of the underground continuous wall, and a jacking pipe receiving platform is reserved in the foundation pit; wherein, the station body includes a top plate, a middle plate and a bottom plate, and the top of the jacking pipe receiving platform matches the design elevation of the middle plate of the station body.

[0007] S2, constructing a first horizontal support assembly and a second horizontal support assembly in the foundation pit; wherein, the first horizontal support assembly is arranged at the design elevation position of the top plate, and the second horizontal support assembly is arranged between the design elevation position of the top plate and the top pipe receiving platform, and the two ends of the first horizontal support assembly are respectively connected to the retaining underground continuous wall, and the two ends of the second horizontal support assembly are respectively connected to the retaining underground continuous wall.

[0008] S3, relying on the jacking pipe receiving platform, construct a temporary ring frame beam corresponding to the outlet of the jacking machine hole on the retaining underground continuous wall, and set up a third support assembly on the inner end face of the temporary ring frame beam; wherein, the bottom beam of the temporary ring frame beam is flush with the height of the jacking pipe receiving platform, and the third support assembly includes a plurality of first additional support units arranged at intervals along the circumferential direction of the temporary ring frame beam, one end of each first additional support unit is connected to the inner end face of the temporary ring frame beam, and the other end is connected to the retaining underground continuous wall, and the support axial force of the first additional support unit can be adjusted.

[0009] S4, adjusting the supporting axial force of each first additional supporting unit to the design value, removing the second horizontal supporting assembly within the range of the temporary ring frame beam, reinforcing the surrounding soil of the outlet of the pipe jacking machine hole, breaking the retaining underground continuous wall on the inner side of the temporary ring frame beam to open an opening corresponding to the outlet of the pipe jacking machine hole on the retaining underground continuous wall.

[0010] S5, jacking the rectangular pipe jacking machine until the hole of the pipe jacking machine is connected with the opening, then receiving the rectangular pipe jacking machine by relying on the pipe jacking receiving platform, and then disassembling and lifting the rectangular pipe jacking machine to complete the receiving construction of the rectangular pipe jacking machine.

[0011] Furthermore, in step S3, constructing a temporary ring frame beam on the underground continuous wall relying on the jacking pipe receiving platform specifically includes the following steps: S31, roughening the underground continuous wall and implanting steel bars within the corresponding range between the underground continuous wall and the temporary ring frame beam; S32, tying up the steel bars of the temporary ring frame beam and connecting them with the steel bars in the enclosing underground continuous wall, and then pre-embedding a connecting steel plate for connecting with the third supporting assembly, and casting to form the temporary ring frame beam.

[0012] Furthermore, the step S5 further includes the following steps: S6, continue to erect multiple second additional support units in the bottom beam area of ​​the temporary ring frame beam; wherein one end of each second additional support unit is connected to the inner end surface of the bottom beam, and the other end is connected to the enclosing underground continuous wall, and the support axial force of the second additional support unit is adjustable; wherein the temporary ring frame beam includes a bottom beam, an upper beam and two side beams; S7, excavating the jacking pipe receiving platform, continuing to excavate the foundation pit to the design elevation of the fourth horizontal support assembly, installing the fourth horizontal support assembly, and then continuing to excavate the foundation pit to the position of the bottom plate, and sequentially installing the bottom plate, the bottom plate cushion layer and the underground negative second floor side wall waterproof structure, pouring the bottom plate and side wall concrete; wherein the fourth horizontal support assembly is arranged between the middle plate and the bottom plate of the station body; S8, detect the concrete strength of the bottom plate, and after determining that the concrete strength of the bottom plate reaches the design strength, sequentially construct the underground second-floor side wall, middle plate, underground first-floor side wall and top plate, and simultaneously dismantle the fourth horizontal support assembly, the second horizontal support assembly, the temporary ring frame beam and the third support assembly. After the concrete strength of the top plate reaches the design strength, backfill the soil and restore the municipal pipelines and roads.

[0013] Further preferably, the step S4 specifically comprises the following steps: S41, using a simplified model to calculate the support axial force of the first additional support unit and the internal force of the temporary ring frame beam, and according to the calculated values, erecting a plurality of the first additional support units at corresponding positions of the upper beam and the two side beams of the temporary ring frame beam, and adjusting the support axial force on the first additional support unit to the design value; S42, removing the second horizontal support assembly corresponding to the temporary ring frame beam; S43, reinforcing the surrounding soil of the outlet of the hole of the pipe jacking machine, breaking the underground continuous wall on the inner side of the temporary ring frame beam to open an opening in the underground continuous wall corresponding to the outlet of the hole of the pipe jacking machine.

[0014] Further preferably, the step S41 specifically includes the following steps: S411, select the underground continuous wall corresponding to the rectangular jacking pipe as the object, simplify the surrounding of the underground continuous wall into a first hinge support, simplify the connection between the underground continuous wall and the first horizontal support assembly into a second hinge support, simplify the first additional support unit, the second horizontal support assembly, the jacking pipe receiving platform and the outer soil of the underground continuous wall into elastic fulcrums, and apply the static water and soil pressure and the rectangular jacking pipe pressure to the underground continuous wall; S412, using the finite element method to calculate the supporting axial force on the first additional supporting unit and the internal force on the temporary ring frame beam; S413, adjusting the number and position of the first additional support units and the size of the temporary ring frame beam according to the calculated support axial force and the internal force of the temporary ring frame beam.

[0015] Further preferably, the step S412 of calculating the supporting axial force on the first additional supporting unit specifically comprises the following steps: Using Formula F h =EIδ calculates the supporting axial force on the first additional supporting unit, wherein E is the elastic modulus of the material, I is the section moment of inertia, and δ is the displacement of the first additional supporting unit simplified to the elastic fulcrum obtained in the software using the finite element method in step S412.

[0016] Further preferably, after step S412, a safety check is performed on the first additional support unit, which specifically includes the following steps: S4121, check the diameter-to-thickness ratio; the calculation formula is: D / t≤100(235 / f y ), where D is the outer diameter of the first additional support unit, t is the thickness of the wall of the first additional support unit, and f y is the yield strength of steel; Verify stiffness; the verification formula is: λ x <λ, where λ x is the slenderness ratio of the first additional support unit, λ is the allowable slenderness ratio of the first additional support unit; Verify strength; the verification formula is: F h / A+M / rW<f, where F h is the axial force of the first additional support unit, in N, A is the cross-sectional area of ​​the first additional support unit, M is the design value of the bending moment after taking into account the eccentricity, r is the plastic development coefficient of the component, W is the resistance moment of the component section, and f is the design value of the compressive strength of the steel; Verify stability; the verification formula is: F h / ψ x A+β m M / rW(1-0.8F h / N Ex )≤φ f , where F h is the axial force of the first additional support unit, in N, β m is the equivalent bending moment coefficient, ψ x is the stability coefficient, A is the cross-sectional area of ​​the first additional support unit, M is the design value of the bending moment after taking into account the eccentricity, r is the plastic development coefficient of the component, W is the resistance moment of the component section, N Ex is the Euler critical force, φ f is the local stability coefficient; S4122, determining whether the diameter-to-thickness ratio, stiffness, strength, and stability of the first additional support unit all meet verification conditions; S4123: when the diameter-to-thickness ratio, stiffness, strength, and stability of the first additional support unit all meet verification conditions, determine that the first additional support unit meets safety standards; S4124, when any one of the diameter-to-thickness ratio, stiffness, strength and stability of the first additional support unit does not meet the verification conditions, it is determined that the first additional support unit does not meet the safety standards, and more first additional support units are preset for verification, and the process returns to step S4121.

[0017] Further preferably, after step S412, the temporary ring frame beam is safety checked, specifically comprising the following steps: Use the verification formula Ne≤R w bx(h o -x / 2)+R g A g '(h o -a') to perform safety calculation on the temporary ring frame beam; where N is the axial force on the temporary ring frame beam, e is the distance from the center of gravity of the steel bar to the point of action of the axial force, R w is the ultimate compressive strength of concrete, b is the section width, x is the height of the concrete compression zone, h o is the effective height of the section, R g is the standard value of tensile or compressive strength of steel bars, A g ' is the cross-sectional area of ​​the steel bars in the compression zone, a' is the steel bar A g 'The distance from the centroid to the nearest edge of the cross section; When the temporary ring frame beam meets the verification formula, it is determined that the current design size meets the structural safety requirements; When the temporary ring frame beam does not meet the verification formula, it is determined that the current design size does not meet the structural safety requirements, the design size of the temporary ring frame beam is readjusted and the safety verification is re-performed.

[0018] Further preferably, the step S43 specifically includes the following steps: S431, grouting reinforcement is performed on the jacking pipe receiving platform, and judging whether the jacking pipe receiving platform meets the grouting standard; S432, when the jacking pipe receiving platform reaches the grouting standard, after the rectangular pipe jacking machine is jacked to the position of the retaining underground continuous wall and the cutter head of the rectangular pipe jacking machine is close to the retaining underground continuous wall, the retaining underground continuous wall is broken on the inner side of the temporary ring frame beam to open an opening in the retaining underground continuous wall corresponding to the outlet of the pipe jacking machine hole.

[0019] Further preferably, the step S8 specifically includes the following steps: S81, after the concrete strength of the bottom plate reaches the design strength, the fourth horizontal support assembly is removed, and the side wall and middle plate structure of the underground negative second floor are constructed; S82, after the concrete strength of the middle plate reaches the design strength, the remaining second horizontal support components are removed, and the side walls of the underground first floor are cast; S83, after the underground negative first floor side wall reaches the design strength, the temporary ring frame beam and the third support assembly are removed, and the top plate and the remaining underground negative first floor side wall are cast; S84, after the concrete of the top plate reaches the designed strength, backfill the soil and restore the road surface and municipal pipelines.

[0020] Compared with the prior art, the present invention has the following beneficial effects: The present invention advances the pipe jacking construction to the station main enclosure stage, and there is no need to wait for the lengthy station main construction to be completed, which can greatly shorten the overall construction period of the subway station; by receiving the rectangular pipe jacking machine on the pipe jacking receiving platform reserved when excavating the foundation pit, the investment of manpower and material resources for additionally building the pipe jacking receiving platform is eliminated, thus avoiding waste; the uneven stress of the underground continuous wall of the enclosure during the pipe jacking construction is balanced by the supporting axial force of the first additional supporting unit, and the temporary ring frame beam has good anti-torsion and mechanical transmission properties, thereby enhancing the stability of the support system. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0022] Figure 1 A schematic top view of a support system when a jacking pipe receiving platform is reserved for a foundation pit in one embodiment of the present invention; Figure 2 It is a side schematic diagram of a foundation pit in one embodiment of the present invention when a jacking pipe receiving platform is reserved; Figure 3 It is a side view schematic diagram of the support system after the jacking pipe receiving platform is removed in one embodiment of the present invention; Figure 4 It is a simplified model schematic diagram for calculating the support system of the rectangular jacking pipe corresponding to the underground continuous wall in one embodiment of the present invention; Figure 5 It is a schematic diagram of a flow chart in one embodiment of the present invention.

[0023] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings in conjunction with the embodiments.

[0024] Description of Figure Numbers: 1. Rectangular jacking pipe; 2. Enclosing underground continuous wall; 3. Temporary ring frame beam; 4. First additional support unit; 5. Second horizontal support assembly; 6. Jacking pipe receiving platform; 7. Top plate; 8. First horizontal support assembly; 9. Second additional support unit; 10. Middle plate; 11. Bottom plate; 12. Fourth horizontal support assembly; 13. Intercepting ditch; 14. First hinge support; 15. Second hinge support; 16. Elastic fulcrum. DETAILED DESCRIPTION

[0025] It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as described in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0028] In addition, the descriptions of "first", "second", etc. in the present invention are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0029] In the existing subway station construction, since there are dense personnel activities around the subway station location and there are great safety risks, it is generally required to isolate the construction scope before the subway station construction, and then set up a retaining underground continuous wall 2 underground to isolate the soil around the foundation pit, and then dig the foundation pit, and then construct a support system in the foundation pit to reinforce and support the retaining underground continuous wall 2. This stage is the station main body enclosure stage, and then the station body is constructed.

[0030] After the main construction of the station is completed, the stability of the wall structure is improved. For safety reasons, the construction unit usually chooses to carry out pipe jacking construction after the main construction of the station is completed. However, the construction period of the main body of the station is long, and the long wait for pipe jacking construction will seriously slow down the construction progress and extend the construction period. Moreover, the main body of the station generally does not include a platform for receiving the pipe jacking machine, so it is necessary to build an additional pipe jacking machine receiving platform in the main body of the station to receive the pipe jacking machine.

[0031] If the jacking construction is set during the main enclosure stage of the station, the wall stability of the underground continuous wall 2 is not high, and a support system is needed to support it. If the support system is not set up reasonably, the bearing capacity of the underground continuous wall 2 will be insufficient. Moreover, during the construction process, the force of the underground continuous wall 2 is complex due to the uneven pressure of the stratum and the soil bin of the jacking pipe. If the support axial force cannot be adjusted in time, the changes in the underground continuous wall 2 will easily cause the support system to twist, ultimately leading to safety problems such as water leakage, cracking and instability of the foundation pit.

[0032] In view of this, the following embodiments all propose methods that can be used for jacking construction during the station body enclosure stage. In the following embodiments, the station body is divided into two layers, including a top plate 7, a middle plate 10 and a bottom plate 11. After construction, the top plate 7, the middle plate 10 and the bottom plate 11 separate the station body into an underground negative first floor and an underground negative second floor. The underground negative first floor is the space range between the top plate 7 and the middle plate 10, and the underground negative second floor is the space range between the bottom plate 11 and the middle plate 10.

[0033] See also Figures 1 to 5 This embodiment provides a receiving construction method for a rectangular jacking pipe in the station main enclosure stage, comprising the following steps: S1. After the construction of the underground continuous wall 2 of the station body is completed, a foundation pit is excavated downward along the inner wall of the underground continuous wall 2, and a jacking pipe receiving platform 6 is reserved in the foundation pit; wherein, the top of the jacking pipe receiving platform 6 matches the design elevation of the middle plate 10 of the station body, and the inner wall of the underground continuous wall 2 is the side wall facing the station body.

[0034] The platform width of the jacking pipe receiving platform 6 is preferably three times the width of the rectangular jacking pipe 1, so as to facilitate the disassembly and hoisting of the rectangular jacking machine in the later stage. The jacking pipe receiving platform 6 is hardened with C20 concrete, providing a place for erecting scaffolding for the construction of the temporary ring frame beam 3, and plays the role of the bottom fulcrum during the jacking pipe construction. The jacking pipe receiving platform 6 can be selected according to the geological conditions to dig the slope at a stable slope rate of 1:1.5 or 1:2, and a drainage ditch 13 is set at the bottom of the slope for drainage. The slope surface is supported by spray anchor to avoid rainwater erosion and weathering of the rock and soil, which causes the softening of the mechanical parameters of the soil in the foundation pit.

[0035] S2, construct a first horizontal support assembly 8 and a second horizontal support assembly 5 in the foundation pit; wherein, the first horizontal support assembly 8 is arranged at the design elevation position of the top plate 7 of the station body, the second horizontal support assembly 5 is arranged between the design elevation position of the top plate 7 and the top pipe receiving platform 6, the second horizontal support assembly 5 and the first horizontal support assembly 8 are parallel and arranged at intervals, the two ends of the first horizontal support assembly are respectively connected to the retaining underground continuous wall 2, and the two ends of the second horizontal support assembly are respectively connected to the retaining underground continuous wall 2.

[0036] S3, relying on the jacking pipe receiving platform 6, a temporary ring frame beam 3 is constructed on the retaining underground continuous wall 2, and a third support assembly is erected on the inner end face of the temporary ring frame beam 3; wherein, the temporary ring frame beam 3 corresponds to the outlet of the jacking machine hole, the bottom beam of the temporary ring frame beam 3 is flush with the height of the jacking pipe receiving platform 6, and the third support assembly includes a plurality of first additional support units 4 arranged at intervals along the circumferential direction of the temporary ring frame beam 3, one end of each first additional support unit 4 is connected to the inner end face of the temporary ring frame beam 3, and the other end is connected to the retaining underground continuous wall 2, and the support axial force of the first additional support unit 4 can be adjusted; the inner end face is the side facing the foundation pit, and the jacking machine hole is the hole left after the rectangular jacking machine enters the foundation pit; in particular, the support axial force of the first additional support unit 4 is carried out through a servo system, thereby adjusting and dynamically adjusting the support axial force to avoid the distortion of the support system due to uneven force.

[0037] S4, adjust the supporting axial force of each first additional supporting unit 4 to the design value, remove the second horizontal supporting assembly 5 within the range of the temporary ring frame beam 3, reinforce the surrounding soil of the outlet of the jacking machine hole, and break the retaining underground continuous wall 2 on the inner side of the temporary ring frame beam 3 to open an opening corresponding to the outlet of the jacking machine hole on the retaining underground continuous wall 2. Note that the retaining underground continuous wall 2 on the inner side of the temporary ring frame beam 3 must be broken after the cutter head of the rectangular jacking machine is close to the outer side of the retaining underground continuous wall 2.

[0038] S5, push the rectangular pipe jacking machine until the hole of the pipe jacking machine is connected with the opening, then rely on the pipe jacking receiving platform 6 to receive the rectangular pipe jacking machine, then disassemble and lift the rectangular pipe jacking machine, and complete the receiving construction of the rectangular pipe jacking 1. Specifically, detect and correct the cutter head posture of the rectangular pipe jacking machine, ensure that the cutter head of the rectangular pipe jacking machine is located at the designed position, and adjust the soil bin pressure in the pipe jacking to an underpressure state, that is, the pressure in the rectangular pipe jacking 1 is lower than the static soil pressure.

[0039] S6, continue to erect multiple second additional support units 9 in the bottom beam area of ​​the temporary ring frame beam 3; wherein, one end of each second additional support unit 9 is connected to the inner end surface of the bottom beam, and the other end is connected to the enclosing underground continuous wall 2, and the supporting axial force of the second additional support unit 9 can be adjusted; wherein the temporary ring frame beam 3 includes a bottom beam, an upper beam and two side beams.

[0040] S7, remove the jacking pipe receiving platform 6, continue to excavate the foundation pit to the design elevation of the fourth horizontal support assembly 12, construct the fourth horizontal support assembly 12, and apply pre-axial force to the fourth horizontal support assembly 12, and then continue to excavate the foundation pit to the position of the bottom plate 11, and successively construct the bottom plate 11, the bottom plate cushion layer and the underground negative second floor side wall waterproof structure, and pour the bottom plate 11 and the side wall concrete; wherein, the fourth horizontal support assembly 12 is arranged between the middle plate 10 and the bottom plate 11 of the station body.

[0041] S8, detect the concrete strength of the bottom plate 11, and after determining that the concrete strength of the bottom plate 11 reaches the design strength, sequentially construct the underground negative second floor side wall, the middle plate 10, the underground negative first floor side wall and the top plate 7, and simultaneously dismantle the fourth horizontal support assembly 12, the second horizontal support assembly 5, the temporary ring frame beam 3 and the third support assembly. After the concrete strength of the top plate 7 reaches the design strength, backfill the soil and restore the municipal pipelines and roads.

[0042] Furthermore, in step S3, constructing a temporary ring frame beam 3 on the underground continuous wall 2 by relying on the jacking pipe receiving platform 6 specifically includes the following steps: S31, within the corresponding range between the underground continuous retaining wall 2 and the temporary ring frame beam 3, the underground continuous retaining wall 2 is roughened and steel bars are implanted.

[0043] S32, tying the steel bars of the temporary ring frame beam 3 and connecting them with the steel bars in the retaining underground continuous wall 2, and then pre-embedding the connecting steel plate for connecting with the third supporting assembly, and casting to form the temporary ring frame beam 3.

[0044] More specifically, the length of the implanted steel bar is 35d (d is the diameter of the steel bar), the scaffolding is set up and the formwork is erected, the steel bars of the temporary ring frame beam 3 are tied, one end of the L-shaped steel bar is welded to the main bars of the enclosing underground continuous wall 2, and the other end is welded to the main bars of the temporary ring frame beam 3. The length of both sides of the L-shaped steel bar is 10d, and the size of the connecting steel plate is 1m×1m×20mm. Then pour C35 concrete, and remove the formwork after the concrete reaches the designed strength.

[0045] In another embodiment, a tripod is constructed at the bottom of the temporary ring frame beam 3 to prevent it from falling, and the tripod is connected to the surrounding underground continuous wall 2 by implanting steel bars.

[0046] Furthermore, the step S4 specifically includes the following steps: S41, using a simplified model to calculate the supporting axial force of the first additional supporting unit 4 and the internal force of the corresponding temporary ring frame beam 3, according to the calculated values, erecting a plurality of the first additional supporting units 4 at the corresponding positions of the upper beam and the two side beams of the temporary ring frame beam 3, and adjusting the supporting axial force on the first additional supporting unit 4 to the design value.

[0047] S42, dismantling the second horizontal support assembly 5 corresponding to the temporary ring frame beam 3.

[0048] S43, reinforcing the surrounding soil of the outlet of the jacking machine hole, breaking the underground continuous wall 2 on the inner side of the temporary ring frame beam 3 to open an opening in the underground continuous wall 2 corresponding to the outlet of the jacking machine hole.

[0049] In this embodiment, step S41 specifically includes the following steps: S411, see Figure 4 , select the retaining underground continuous wall 2 corresponding to the rectangular jacking pipe 1 as the object, simplify the surrounding of the retaining underground continuous wall 2 into a first hinge support 14, simplify the connection between the retaining underground continuous wall 2 and the first horizontal support assembly 8 into a second hinge support 15, simplify the first additional support unit 4, the second horizontal support assembly 5, the jacking pipe receiving platform 6 and the outer soil of the retaining underground continuous wall 2 into an elastic fulcrum 16, and apply the static water and soil pressure (trapezoidal arrow frame) and the rectangular jacking pipe 1 pressure (rectangular arrow frame) to the retaining underground continuous wall 2.

[0050] S412, using the finite element method to calculate the supporting axial force on the first additional supporting unit 4 and the internal force on the temporary ring frame beam 3, the internal force of the temporary ring frame beam 3 including the supporting axial force and the bending moment.

[0051] S413, adjusting the number and position of the first additional support units 4 and the size of the temporary ring frame beam 3 according to the calculated support axial force and the internal force of the temporary ring frame beam 3.

[0052] More specifically, the static water-soil pressure is divided into water pressure and soil pressure, which increase along the depth direction of the stratum. The normal water level at the project site can be known based on geological survey data. When conservatively calculating, the water level at the ground surface can be regarded as zero water level. Along the depth direction, the water pressure per linear meter of the retaining underground continuous wall 2 is P1=γ1H1 (γ1 is the bulk density of water, and H1 is the depth of the groundwater level). Along the depth direction, the earth pressure per linear meter of the retaining underground continuous wall 2 is P2=aγ2H2. When the jacking pipe approaches the retaining underground continuous wall 2 (at this time, the retaining underground continuous wall 2 has not been removed) (a is the average soil lateral earth pressure coefficient, which can be obtained by multiplying the lateral earth pressure coefficient of each layer of soil in the geological survey data by the soil layer thickness, and then dividing the sum by the total soil thickness. γ2 is the average soil bulk density, which can be obtained by multiplying the bulk density of each layer of soil in the geological survey data by the soil layer thickness, and then dividing the sum by the total soil thickness. H2 is the soil depth). The magnitude of the jacking pipe thrust on the retaining underground continuous wall 2 can be determined based on construction experience or actual on-site conditions.

[0053] Further, the calculation of the supporting axial force on the first additional supporting unit 4 in step S412 specifically includes the following steps: Using Formula F h =EIδ calculates the supporting axial force on the first additional supporting unit 4, wherein E is the elastic modulus of the material, I is the section moment of inertia, and δ is the displacement of the first additional supporting unit 4 simplified to the elastic fulcrum 16 obtained in the software using the finite element method in step S412.

[0054] The calculation formula of the section inertia moment is: I = π / 64 (R 2 -r 2 ), R is the outer ring diameter, r is the inner ring diameter.

[0055] Furthermore, after step S412, the first additional support unit 4 is safety checked to ensure that the first additional support unit 4 meets the specification "Steel Structure Design Standard" (GB50017-2017), which specifically includes the following steps: S4121, check the diameter-to-thickness ratio; the calculation formula is: D / t≤100(235 / f y ), where D is the outer diameter of the first additional support unit 4, t is the wall thickness of the first additional support unit 4, and f y is the yield strength of steel.

[0056] Verify stiffness; the verification formula is: λ x <λ, where λ x is the slenderness ratio of the first additional supporting unit 4 , and λ is the allowable slenderness ratio of the first additional supporting unit 4 .

[0057] Verify strength; the verification formula is: F h / A+M / rW<f, where F h is the supporting axial force of the first additional supporting unit 4, in N, A is the cross-sectional area of ​​the first additional supporting unit 4, M is the design value of the bending moment after taking into account the eccentricity, r is the plastic development coefficient of the component, W is the section resistance moment of the component, and f is the design value of the compressive strength of the steel.

[0058] Verify stability; the verification formula is: F h / ψ x A+β m M / rW(1-0.8F h / N Ex )≤φ f , where ψ x is the stability coefficient, N Ex is the Euler critical force, β m is the equivalent bending moment coefficient, φ f is the local stability coefficient.

[0059] In the above formula, the calculation method of each symbol can be found and calculated according to the "Steel Structure Design Standard" (GB50017-2017), which will not be repeated here.

[0060] S4122, determining whether the diameter-to-thickness ratio, stiffness, strength and stability of the first additional support unit 4 all meet verification conditions.

[0061] S4123: When the diameter-to-thickness ratio, stiffness, strength and stability of the first additional support unit 4 all meet verification conditions, it is determined that the first additional support unit 4 meets the safety standards.

[0062] S4124, when any one of the diameter-to-thickness ratio, stiffness, strength and stability of the first additional support unit 4 does not meet the verification conditions, it is determined that the first additional support unit 4 does not meet the safety standards, and more first additional support units 4 are preset for verification, and the process returns to step S4121.

[0063] In this embodiment, after step S412, the temporary ring frame beam 3 is safety checked, which specifically includes the following steps: Use the verification formula Ne≤R w bx(h o -x / 2)+R g A g '(h o -a') perform safety calculation on the temporary ring frame beam 3; where N is the axial force on the temporary ring frame beam 3, e is the distance from the center of gravity of the steel bar to the point of action of the axial force, R wis the ultimate compressive strength of concrete, b is the section width, x is the height of the concrete compression zone, h o is the effective height of the section, R g is the standard value of tensile or compressive strength of steel bars, A g ' is the cross-sectional area of ​​the steel bars in the compression zone, a' is the steel bar A g 'The distance from the centroid to the nearest edge of the cross section.

[0064] When the temporary ring frame beam 3 satisfies the verification formula, it is determined that the current design size meets the structural safety requirements.

[0065] When the temporary ring frame beam 3 does not satisfy the calculation formula, it is determined that the current design size does not meet the structural safety requirements, the design size of the temporary ring frame beam 3 is readjusted and the safety calculation is re-performed.

[0066] Similarly, after the retaining underground continuous wall 2 is broken, there is no thrust force in the load on the retaining underground continuous wall 2. The same method as above is used to perform safety calculations on the second additional support unit 9 and the temporary ring frame beam 3 for the remaining retaining underground continuous wall 2. If the calculations meet the design requirements, the construction can be carried out according to the preset number and position of the second additional support unit 9 and the size of the temporary ring frame beam 3. If the design requirements are not met, it is necessary to continuously adjust until the design requirements are met.

[0067] Furthermore, the step S43 specifically includes the following steps: S431, grouting reinforcement is performed on the jacking pipe receiving platform 6, and it is determined whether the jacking pipe receiving platform 6 meets the grouting standard.

[0068] Specifically, 42 cement slurry is used to grout the top pipe receiving platform 6, and the grouting pressure is 0.8MPa~1MPa. After the grouting is completed, it is judged whether the grouting effect meets the grouting standard (using drilling core sampling to check whether the 28-day unconfined compressive strength is not less than 1.0MPa, and the permeability coefficient is not greater than cm / s). If the grouting standard cannot be met, supplementary grouting is required.

[0069] S432, when the jacking pipe receiving platform 6 reaches the grouting standard, after the rectangular pipe jacking machine is jacked to the position of the retaining underground continuous wall 2 and the cutter head of the rectangular pipe jacking machine is close to the retaining underground continuous wall 2, the retaining underground continuous wall 2 is broken on the inner side of the temporary ring frame beam 3 to open an opening in the retaining underground continuous wall 2 corresponding to the outlet of the pipe jacking machine hole.

[0070] It is worth noting that, in view of the existence of the holes of the pipe jacking machine, the retaining underground continuous wall 2 becomes a cantilever structure. In order to accurately obtain the supporting axial force and the internal force of the retaining underground continuous wall 2, the above simplified model can also be used for calculation. The model boundaries are as described above. The soil pressure changes after the pipe jacking construction. The upper and lower soil pressures of the rectangular pipe 1 are based on the static soil pressure, and the bottom of the rectangular pipe jacking is based on the lateral soil pressure generated by the upper soil pressure plus the self-weight of the pipe jacking. The finite element method can be used to obtain the supporting axial force and the internal force of any interface of the retaining underground continuous wall 2, and then the reasonableness of the support layout and the bearing capacity of the retaining underground continuous wall 2 can be verified.

[0071] Furthermore, the step S8 specifically includes the following steps: S81, after the concrete strength of the bottom plate 11 reaches the design strength, the fourth horizontal support assembly 12 is removed, and the structure of the underground negative second floor side wall and the middle plate 10 is constructed.

[0072] S82, after the concrete strength of the middle plate 10 reaches the design strength, the remaining second horizontal support components 5 are removed, the underground negative layer waterproof structure is constructed, and the underground negative layer side walls are cast.

[0073] S83, after the underground negative first floor side wall reaches the design strength, remove the temporary ring frame beam 3 and the third supporting assembly, construct the top plate 7 waterproof structure, cast the top plate 7 and the remaining underground negative first floor side wall; roughen the side wall around the jacking machine hole, and pre-embed the water stop. In order to fill the gap between the temporary ring frame beam 3 and the jacking machine hole, it is necessary to cast the gap to form a post-cast ring beam. After the concrete strength of the post-cast ring beam reaches the design strength, remove the temporary ring frame beam 3.

[0074] S84, after the concrete of the top plate 7 reaches the designed strength, backfill the soil and restore the road surface and municipal pipelines.

[0075] In the present invention, by analyzing the stress conditions of the support system and the existing underground continuous wall 2 during the construction process, the support system design is made more reasonable and effective, and the bearing capacity of the underground continuous wall 2 can be verified; the jacking pipe receiving platform 6 reserved in the foundation pit can not only receive the rectangular jacking pipe machine, but also transmit lateral constraints during the jacking pipe construction process to ensure the overall stability of the foundation pit; the servo system in the support system adjusts the support axial force and the integrated cast temporary ring frame beam 3 can dynamically adjust the support axial force during the jacking pipe construction process to adapt to deformation and avoid twisting of the support system; in addition, it can also provide fulcrums for the upper and lower enclosures of the underground continuous wall 2, reduce the hole effect of the underground continuous wall 2, and reduce stress concentration; finally, the post-cast ring beam of the present invention is tightly connected to the station body to avoid safety risks such as water leakage.

[0076] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A receiving construction method for rectangular jacking pipes in the station main enclosure stage, characterized in that: The following steps are involved: S1, after the construction of the underground continuous wall of the station body is completed, a foundation pit is excavated downward along the inner wall of the underground continuous wall, and a jacking pipe receiving platform is reserved in the foundation pit; wherein the station body includes a top plate, a middle plate and a bottom plate, and the top of the jacking pipe receiving platform matches the design elevation of the middle plate; S2, constructing a first horizontal support assembly and a second horizontal support assembly in the foundation pit; wherein the first horizontal support assembly is arranged at the design elevation position of the top plate, and the second horizontal support assembly is arranged between the design elevation position of the top plate and the top pipe receiving platform, and both ends of the first horizontal support assembly and the second horizontal support assembly are connected to the corresponding underground continuous wall; S3, relying on the jacking pipe receiving platform, construct a temporary ring frame beam corresponding to the outlet of the jacking machine hole on the retaining underground continuous wall, and set up a third support assembly on the inner end surface of the temporary ring frame beam; wherein the bottom beam of the temporary ring frame beam is flush with the height of the jacking pipe receiving platform, and the third support assembly includes a plurality of first additional support units arranged at intervals along the circumferential direction of the temporary ring frame beam, one end of each first additional support unit is connected to the inner end surface of the temporary ring frame beam, and the other end is connected to the retaining underground continuous wall, and the support axial force of the first additional support unit can be adjusted; S4, adjusting the supporting axial force of each first additional supporting unit to the design value, removing the second horizontal supporting assembly within the range of the temporary ring frame beam, reinforcing the surrounding soil of the outlet of the jacking machine hole, breaking the retaining underground continuous wall on the inner side of the temporary ring frame beam to open an opening corresponding to the outlet of the jacking machine hole on the retaining underground continuous wall; S5, pushing the rectangular pipe jacking machine until the hole of the pipe jacking machine is connected with the opening, then receiving the rectangular pipe jacking machine by relying on the pipe jacking receiving platform, and then disassembling and lifting the rectangular pipe jacking machine.

2. The receiving construction method of the rectangular jacking pipe in the station main enclosure stage according to claim 1 is characterized in that: In step S3, constructing a temporary ring frame beam on the underground continuous wall by relying on the jacking pipe receiving platform specifically includes the following steps: S31, roughening the underground continuous wall and implanting steel bars within the corresponding range between the underground continuous wall and the temporary ring frame beam; S32, tying up the steel bars of the temporary ring frame beam and connecting them with the steel bars in the enclosing underground continuous wall, and then pre-embedding a connecting steel plate for connecting with the third supporting assembly, and casting to form the temporary ring frame beam.

3. The receiving construction method of the rectangular jacking pipe in the station main body enclosure stage according to claim 1 is characterized in that: The step S5 further includes the following steps: S6, continue to erect multiple second additional support units in the bottom beam area of ​​the temporary ring frame beam; wherein one end of each second additional support unit is connected to the inner end surface of the bottom beam, and the other end is connected to the enclosing underground continuous wall, and the support axial force of the second additional support unit is adjustable; wherein the temporary ring frame beam includes a bottom beam, an upper beam and two side beams; S7, excavating the jacking pipe receiving platform, continuing to excavate the foundation pit to the design elevation of the fourth horizontal support assembly, installing the fourth horizontal support assembly, and then continuing to excavate the foundation pit to the position of the bottom plate, and sequentially installing the bottom plate, the bottom plate cushion layer and the underground negative second floor side wall waterproof structure, pouring the bottom plate and side wall concrete; wherein the fourth horizontal support assembly is arranged between the middle plate and the bottom plate of the station body; S8, detect the concrete strength of the bottom plate, and after determining that the concrete strength of the bottom plate reaches the design strength, sequentially construct the underground second-floor side wall, middle plate, underground first-floor side wall and top plate, and simultaneously dismantle the fourth horizontal support assembly, the second horizontal support assembly, the temporary ring frame beam and the third support assembly. After the concrete strength of the top plate reaches the design strength, backfill the soil and restore the municipal pipelines and roads.

4. The receiving construction method of the rectangular jacking pipe in the station main body enclosure stage according to claim 3 is characterized in that: The step S4 specifically comprises the following steps: S41, using a simplified model to calculate the support axial force of the first additional support unit and the internal force of the temporary ring frame beam, and according to the calculated values, erecting a plurality of the first additional support units at corresponding positions of the upper beam and the two side beams of the temporary ring frame beam, and adjusting the support axial force on the first additional support unit to the design value; S42, removing the second horizontal support assembly corresponding to the temporary ring frame beam; S43, reinforcing the surrounding soil of the outlet of the hole of the pipe jacking machine, breaking the underground continuous wall on the inner side of the temporary ring frame beam to open an opening in the underground continuous wall corresponding to the outlet of the hole of the pipe jacking machine.

5. The receiving construction method of the rectangular jacking pipe in the station main body enclosure stage according to claim 4 is characterized in that: The step S41 specifically includes the following steps: S411, select the underground continuous wall corresponding to the rectangular jacking pipe as the object, simplify the surrounding of the underground continuous wall into a first hinge support, simplify the connection between the underground continuous wall and the first horizontal support assembly into a second hinge support, simplify the first additional support unit, the second horizontal support assembly, the jacking pipe receiving platform and the outer soil of the underground continuous wall into elastic fulcrums, and apply the static water and soil pressure and the rectangular jacking pipe pressure to the underground continuous wall; S412, using the finite element method to calculate the supporting axial force on the first additional supporting unit and the internal force on the temporary ring frame beam; S413, adjusting the number and position of the first additional support units and the size of the temporary ring frame beam according to the calculated support axial force and the internal force of the temporary ring frame beam.

6. The receiving construction method of the rectangular jacking pipe in the station main body enclosure stage according to claim 5 is characterized in that: The step S412 of calculating the supporting axial force on the first additional supporting unit specifically includes the following steps: Using Formula F h =EIδ calculates the supporting axial force on the first additional supporting unit, wherein E is the elastic modulus of the material, I is the section moment of inertia, and δ is the displacement of the first additional supporting unit simplified to the elastic fulcrum obtained in the software using the finite element method in step S412.

7. The receiving construction method of the rectangular jacking pipe in the station main body enclosure stage according to claim 5 is characterized in that: After step S412, the first additional support unit is subjected to safety verification, which specifically includes the following steps: S4121, check the diameter-to-thickness ratio; the calculation formula is: D / t≤100(235 / f y ), where D is the outer diameter of the first additional support unit, t is the thickness of the wall of the first additional support unit, and f y is the yield strength of steel; Verify stiffness; the verification formula is: λ x <λ, where λ x is the slenderness ratio of the first additional support unit, λ is the allowable slenderness ratio of the first additional support unit; Verify strength; the verification formula is: F h / A+M / rW<f, where F h is the axial force of the first additional support unit, A is the cross-sectional area of ​​the first additional support unit, M is the design value of the bending moment after taking into account the eccentricity, r is the plastic development coefficient of the component, W is the resistance moment of the component section, and f is the design value of the compressive strength of the steel; Verify stability; the verification formula is: F h / ψ x A+β m M / rW(1-0.8F h / N Ex )≤φ f , where F h is the axial force of the first additional support unit, β m is the equivalent bending moment coefficient, ψ x is the stability coefficient, A is the cross-sectional area of ​​the first additional support unit, M is the design value of the bending moment after taking into account the eccentricity, r is the plastic development coefficient of the component, W is the resistance moment of the component section, N Ex is the Euler critical force, φ f is the local stability coefficient; S4122, determining whether the diameter-to-thickness ratio, stiffness, strength, and stability of the first additional support unit all meet verification conditions; S4123: when the diameter-to-thickness ratio, stiffness, strength, and stability of the first additional support unit all meet verification conditions, determine that the first additional support unit meets safety standards; S4124, when any one of the diameter-to-thickness ratio, stiffness, strength and stability of the first additional support unit does not meet the verification conditions, it is determined that the first additional support unit does not meet the safety standards, and more first additional support units are preset for verification, and the process returns to step S4121.

8. The receiving construction method of the rectangular jacking pipe in the station main body enclosure stage according to claim 5 is characterized in that: After step S412, the temporary ring frame beam is safety checked, which specifically includes the following steps: Use the verification formula Ne≤R w bx(h o -x / 2)+R g A g '(h o -a') to perform safety calculation on the temporary ring frame beam; where N is the axial force on the temporary ring frame beam, e is the distance from the center of gravity of the steel bar to the point of action of the axial force, R w is the ultimate compressive strength of concrete, b is the section width, x is the height of the concrete compression zone, h o is the effective height of the section, R g is the standard value of tensile or compressive strength of steel bars, A g ' is the cross-sectional area of ​​the steel bars in the compression zone, a' is the steel bar A g 'The distance from the centroid to the nearest edge of the cross section; When the temporary ring frame beam meets the verification formula, it is determined that the current design size meets the structural safety requirements; When the temporary ring frame beam does not meet the verification formula, it is determined that the current design size does not meet the structural safety requirements, the design size of the temporary ring frame beam is readjusted and the safety verification is re-performed.

9. The receiving construction method of the rectangular jacking pipe in the station main body enclosure stage according to claim 4 is characterized in that: The step S43 specifically includes the following steps: S431, grouting reinforcement is performed on the jacking pipe receiving platform, and judging whether the jacking pipe receiving platform meets the grouting standard; S432, when the jacking pipe receiving platform reaches the grouting standard, after the rectangular pipe jacking machine is jacked to the position of the retaining underground continuous wall and the cutter head of the rectangular pipe jacking machine is close to the retaining underground continuous wall, the retaining underground continuous wall is broken on the inner side of the temporary ring frame beam to open an opening in the retaining underground continuous wall corresponding to the outlet of the pipe jacking machine hole.

10. The receiving construction method of the rectangular jacking pipe in the station main body enclosure stage according to claim 3 is characterized in that: The step S8 specifically includes the following steps: S81, after the concrete strength of the bottom plate reaches the design strength, the fourth horizontal support assembly is removed, and the side wall and middle plate structure of the underground negative second floor are constructed; S82, after the concrete strength of the middle plate reaches the design strength, the remaining second horizontal support components are removed, and the side walls of the underground first floor are cast; S83, after the underground negative first floor side wall reaches the design strength, the temporary ring frame beam and the third support assembly are removed, and the top plate and the remaining underground negative first floor side wall are cast; S84, after the concrete of the top plate reaches the designed strength, backfill the soil and restore the road surface and municipal pipelines.

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