A method for underground excavation construction of an enlarged station of a subway station shield tunnel

Abstract

The application discloses a subway station shield tunnel upper expansion station excavation construction method, through three layers of pilot holes, three layers are upper, middle and lower three layers, after excavation to the right line and the left line of the main line tunnel, right line and left line main line tunnel excavation is started respectively, the main line tunnel adopts three-step method construction, foam concrete is backfilled in the shield tunnel in advance, collapse of the tunnel during chiseling is avoided, when the cross passage is constructed to the intersection with the main line tunnel, shield segment chiseling is carried out, after chiseling is completed, the cross passage is continuously constructed, tunnel excavation adopts artificial cooperation with machinery according to geological and construction progress requirements, if direct excavation cannot be carried out in mechanical excavation, a breaking hammer or a milling head is used for breaking, and blasting excavation can also be used according to geological conditions and construction conditions, so that the tunnel can be excavated and treated quickly, tunnel excavation efficiency is improved, and the method is especially suitable for excavation of urban subway stations.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of shield tunneling, more particularly, to a method for expanding a station upward from a shield tunnel. BACKGROUND

[0002] Currently, the conventional shield interval tunnel is in the form of double-hole double-line, and after the construction of the station bottom structure is completed, the conditions for the shield to pass through the station can be provided.

[0003] The station structure is complex and the construction period is long, so the construction plan of the shield tunnel is inevitably subject to the construction progress of the station, and in the process of tunneling, secondary collapse is also prone to occur, causing people to be trapped or casualties.

[0004] Therefore, in order to improve the efficiency of shield tunneling, a method for expanding a station upward from a shield tunnel is needed to solve the above problems. SUMMARY

[0005] The present application is proposed to solve the problems in the prior art and provides a method for expanding a station upward from a shield tunnel.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical scheme: a method for expanding a station upward from a shield tunnel, comprising the following steps:

[0007] S1, the shaft is constructed to a position about 1-2m below the air duct arch top elevation, the bottom is temporarily sealed for the first time, the air duct arch part is constructed with a large pipe shed, the shaft is excavated to a position about 2m below the air duct upper step bottom plate, the bottom is temporarily sealed for the second time, the air duct upper step shaft enclosure structure is removed, steel frame support is densely arranged at the opening position, and then the air duct upper step excavation and support construction is performed. During the excavation and support process, the face advance curtain grouting is performed, the air duct upper step is excavated to the air duct end wall position, and the end is sealed;

[0008] S2, the shaft is excavated to about 1-2m below the air duct middle step-1 hole bottom plate, the bottom is temporarily sealed for the third time. The air duct middle step-1 hole shaft enclosure structure is removed, steel frame support is densely arranged at the opening position, and then the air duct middle step-1 hole excavation and support construction is performed. During the excavation and support process, the face advance curtain grouting is performed, the air duct middle step-1 hole is excavated to the end wall position, and the end is sealed;

[0009] S3, the shaft is excavated to about 1-2m below the hole bottom plate of the air duct middle step-2, the fourth temporary bottom sealing is performed, the air duct middle step-2 hole shaft enclosure structure is removed, the steel frame support is densely arranged at the construction opening position, and then the air duct middle step-2 hole excavation support construction is performed. The face advance curtain grouting is performed during the excavation support process. Before the air duct middle step-2 hole is excavated, the shield segment foam concrete backfill construction in the air duct excavation area should be completed and the design strength requirement is achieved. Meanwhile, the steel structure support roof reinforcement measures inside the shield segment in the air duct excavation adjacent area should be completed.

[0010] S4, when the shield segment is reached during the excavation process, the upper shield segment and the foam concrete are removed piece by piece, the primary support and the temporary support construction are timely performed, the air duct middle step-2 hole is excavated to the end wall position, the end is sealed, and the middle step-1 and the middle step-2 between the cross passage middle section frame construction is performed. The frame can provide sufficient construction operation platform for the expanded tunnel section, such as the excavator, the earth removal and the like. The cross passage beam plate at the corresponding position is cut off and moved up, and the frame is installed. During the air duct construction process, the expanded tunnel end line advance support is constructed in opportunity. After the line advance support is completed, the expanded tunnel end reinforcement and the cross passage wall stress system conversion are performed. The cross passage wall and the corresponding position beam plate are removed, the cross passage wall inner support rib is cut off according to the expanded tunnel arch design position, the steel ring support is installed and connected with the cross passage wall inner support rib, so that the stress of the wall inner support rib is converted to the steel ring support.

[0011] S5, the shaft is excavated to the design elevation of the shaft bottom, the bottom is sealed, the air duct lower step shaft enclosure structure is removed, the steel frame support is densely arranged at the construction opening position, and then the air duct lower step excavation support construction is performed. When the shield segment is reached during the excavation process, the lower shield segment and the foam concrete are removed piece by piece, the primary support and the temporary support construction are timely performed, the air duct lower step is excavated to the end wall position, the end is sealed. The beam plate at the corresponding position is cut off and the frame is lengthened. The whole frame construction is completed, and the installation construction of the expanded tunnel end steel ring support is continuously performed. After the above construction is completed, the expanded construction of the line tunnel can be performed.

[0012] Preferably, the upper step excavation height is 3m, and the primary support is timely constructed after the excavation is completed, the footage is 2 pieces, the volume is 25 square meters per meter, and the hole residue is directly backfilled to the segment bottom.

[0013] Preferably, the middle step excavates the soil and rock outside the segment, and the excavation height is 2.62m, and the steel frame is erected on the same side.

[0014] Preferably, the middle step is taken out after the top block is loosened by the excavator, then the adjacent block near the tunnel side wall is removed, the hole residue is directly transported out, the steel frame on the side is timely erected after the middle step segment is removed, and the upper middle step is constructed by the micro-step method with a step distance of 1.5m.

[0015] Preferably, the height of the lower bench excavation is 3.5m, and the left and right inverted edge construction is adopted, the left and right arch foot initial supports are longitudinally staggered by 5m for excavation, and the initial support is constructed in time after the completion of excavation; the hole slag is directly transported out of the hole

[0016] Preferably, the excavation mode of the upper bench, the middle bench and the lower bench adopts inverted arch excavation, and the excavation height is 1.145m, the initial support is closed in time after the completion of excavation, and the plain concrete is backfilled.

[0017] The technical effect and advantages of the present application are as follows: the underground excavation construction method for the upper expansion of the subway station shield tunnel provided by the present application has three layers of guide holes, namely upper, middle and lower layers, and after the right line and the left line of the main line tunnel are excavated, the right line and the left line of the main line tunnel are excavated respectively, the main line tunnel is constructed by the three-step method, the foam concrete is backfilled in the shield tunnel in advance to avoid collapse of the tunnel when the tunnel is drilled, and when the cross passage is constructed to the intersection with the main line tunnel, the shield segment is drilled, and the cross passage is continuously constructed after the drilling is completed.

[0018] The tunnel excavation is artificially combined with machinery according to the geological and construction progress requirements, if the mechanical excavation cannot be directly excavated, a breaking hammer or a milling head is used for breaking, or blasting excavation is used according to the geological conditions and construction conditions, so that the tunnel can be quickly excavated and processed, the tunnel excavation efficiency is improved, and the method is especially suitable for the excavation of urban subway stations, and can effectively prevent the collapse phenomenon in the excavation process and reduce the loss of property. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 The process flowchart of the present application is shown in the figure;

[0020] Figure 2 The structure schematic diagram of the urban underground excavation subway station of the present application is shown in the figure;

[0021] Figure 3 The cross passage profile schematic diagram of the present application is shown in the figure;

[0022] Figure 4 The upper bench construction schematic diagram of the cross passage of the present application is shown in the figure;

[0023] Figure 5 The middle bench-1 construction schematic diagram of the cross passage of the present application is shown in the figure;

[0024] Figure 6 The middle bench-2 construction schematic diagram of the cross passage of the present application is shown in the figure;

[0025] Figure 7 The middle bench-2 and shield pipeline segment breaking construction schematic diagram of the present application is shown in the figure;

[0026] Figure 8A portal segment profile view of the present application;

[0027] Figure 9 A portal segment structure schematic view of the present application;

[0028] Figure 10 A portal segment structure schematic view of the present application;

[0029] Figure 11 A portal segment structure schematic view of the present application; DETAILED DESCRIPTION

[0030] In order to make the purpose, technical scheme and advantages of the present application more clear and understandable, the present application is further described in detail below in combination with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the present application.

[0031] The overall construction scheme of the present application is as follows:

[0032] The two side cross passages are excavated to the right line and left line of the main line tunnel through three layers of pilot holes (the three layers are upper, middle and lower layers, respectively, as shown in Figure 3 ), and then the right line and left line of the main line tunnel is excavated, respectively. The main line tunnel is constructed by the three-step method, as shown in Figure 3 , the foam concrete is backfilled in the shield tunnel in advance (to avoid collapse of the tunnel when chiseling), the shield segment is chiseled when the cross passage is constructed to the intersection with the main line tunnel, and the cross passage is continuously constructed after the chiseling is completed.

[0033] The tunnel excavation is performed by artificial and mechanical cooperation according to the geological and construction progress requirements. If the mechanical excavation cannot be directly excavated, a breaking hammer or a milling head is used for breaking, or blasting excavation is used according to the geological conditions and construction conditions.

[0034] Embodiment 1

[0035] As shown in Figures 1-11 , a subsurface excavation construction method for expanding a subway station shield tunnel, comprising the following steps:

[0036] S1, the shaft is constructed to a position about 1-2m below the air duct arch top elevation, the first temporary bottom sealing is performed, the air duct arch portion advanced large pipe shed is constructed, the shaft is excavated to a position about 2m below the air duct upper step bottom plate, the second temporary bottom sealing is performed, the air duct upper step shaft enclosure structure is chiseled, and the opening position is densely arranged with steel frame support. Then the air duct upper step excavation and support construction is performed. The working face advanced curtain grouting is performed during the excavation and support process, the air duct upper step is excavated to the air duct end wall position, and the end is sealed;

[0037] S2, the shaft is excavated to about 1-2m below the hole bottom plate of the air duct middle step-1, and the third temporary bottom sealing is performed. The shaft enclosure of the air duct middle step-1 hole is removed, steel frames are densely arranged for supporting the construction opening position, then the air duct middle step-1 hole excavation and support construction are performed, the face advance curtain grouting is performed during the excavation and support, and the air duct middle step-1 hole is excavated to the end wall position, and the end is sealed;

[0038] S3, the shaft is excavated to about 1-2m below the hole bottom plate of the air duct middle step-2, and the fourth temporary bottom sealing is performed. The shaft enclosure of the air duct middle step-2 hole is removed, steel frames are densely arranged for supporting the construction opening position, then the air duct middle step-2 hole excavation and support construction are performed. The face advance curtain grouting is performed during the excavation and support, and before the air duct middle step-2 hole is excavated, the foam concrete backfill construction in the shield segment of the air duct excavation area should be completed and the design strength requirement should be met. At the same time, the steel structure support and reinforcement measures in the shield segment inside the air duct excavation adjacent area should be completed.

[0039] S4, when the shield segment is reached during the excavation, the upper shield segment and the foam concrete are removed piece by piece, the primary support and temporary support construction are timely performed, the air duct middle step-2 hole is excavated to the end wall position, the end is sealed, and the middle step-1 and the middle step-2 between the horizontal passage middle section frame construction (the lower step stage frame bottom is constructed after the lower step is excavated in the fifth step) is performed. The frame can provide sufficient construction operation platform for the expanded tunnel section, such as convenient excavator, earth removal and other construction operations. The specific frame construction is shown in Figure 8 and Figure 9 , the horizontal passage beam plate at the corresponding position is cut off and moved up, and the frame is installed. During the air duct construction, the expanded tunnel end head advance support is constructed in opportunity. After the advance support of the main line is completed, the expanded tunnel end head reinforcement and the horizontal passage wall stress system conversion are performed. The specific process is shown in Figure 10 . The horizontal passage wall and the beam plate at the corresponding position are removed (the expanded tunnel end head construction is performed according to the middle step and the lower step construction stage), and the horizontal passage wall inner support rib is cut off according to the design position of the expanded tunnel arch part, the steel ring support is installed, and is connected with the horizontal passage wall inner support rib, so that the stress of the wall inner support rib is converted to the steel ring support;

[0040] S5, the shaft is excavated to the design elevation of the shaft bottom, the bottom is sealed, the air duct lower step shaft enclosure is removed, and steel frames are densely arranged for supporting the construction opening position. Then the air duct lower step excavation and support construction are performed. When the shield segment is reached during the excavation, the lower shield segment and the foam concrete are removed piece by piece, the primary support and temporary support construction are timely performed, the air duct lower step is excavated to the end wall position, the end is sealed, the beam plate at the corresponding position is cut off, the frame is lengthened, the whole frame construction is completed, and the installation construction of the steel ring support of the expanded tunnel end head is continuously performed. After the above construction is completed, the expanded construction of the main line tunnel can be performed.

[0041] The upper bench excavation height is 3 m, and initial support is applied in time after the excavation is completed. The footage is 2 bays, i.e. 1.5 m, and the volume is 25 cubic meters per meter, and the hole residue is directly backfilled to the bottom of the pipe piece.

[0042] The middle bench excavates the soil and rock outside the pipe piece, and the excavation height is 2.62 m, and a steel frame is erected on the same side. The middle bench is removed by a excavator after the top block is loosened, and then the adjacent block near the tunnel side wall is removed, the hole residue is directly transported out, the steel frame on the same side is erected in time after the middle bench pipe piece is broken, the upper middle bench is constructed by using a micro-bench method, the bench step distance is 1.5 m, the lower bench excavation height is 3.5 m, and the left and right inverted edge construction is divided, the left and right arch foot initial support is longitudinally staggered by 5 m, initial support is applied in time after the excavation is completed, the hole residue is directly transported out of the hole, the excavation method of the upper bench, the middle bench and the lower bench is inverted arch excavation, the excavation height is 1.145 m, the initial support is closed in time after the excavation is completed, and the backfilling of plain concrete is performed.

[0043] Finally, it should be noted that: the above only for the preferred embodiments of the present application, and not for limiting the present application, although the present application is described in detail with reference to the foregoing embodiments, for those skilled in the art, it still can modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part of the technical features, any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application, should be included in the protection scope of the present application.

Claims

1. A method for the underground excavation of a subway station above a shield tunnel, characterized in that: Includes the following steps: S1. The shaft is excavated to a position 1-2m below the top elevation of the ventilation duct arch. The first temporary bottom sealing is carried out, and the large pipe shed of the ventilation duct arch is constructed. The shaft is excavated to a position 2m below the bottom slab of the upper step of the ventilation duct. The second temporary bottom sealing is carried out, and the retaining structure of the shaft of the upper step of the ventilation duct is removed. The steel frame is densely arranged for support at the construction opening position. Then the excavation and support construction of the upper step of the ventilation duct is carried out. During the excavation and support process, the face is grouted with the curtain grout. The upper step of the ventilation duct is excavated to the position of the end wall of the ventilation duct and then sealed. S2. The shaft is excavated to 1-2m below the bottom slab of the ventilation duct middle step-1 tunnel. The third temporary bottom sealing is carried out. The retaining structure of the shaft of the ventilation duct middle step-1 tunnel is removed. The steel frame support is densely arranged at the construction opening position. Then the excavation and support construction of the ventilation duct middle step-1 tunnel is carried out. During the excavation and support process, the face is grouted in advance. The ventilation duct middle step-1 tunnel is excavated to the end wall position and then sealed. S3. The shaft is excavated to 1-2m below the bottom slab of the ventilation duct middle step-2 tunnel. The fourth temporary bottom sealing is carried out, the retaining structure of the shaft of the ventilation duct middle step-2 tunnel is removed, and the steel frame support is densely arranged at the construction opening location. Then, the excavation and support construction of the ventilation duct middle step-2 tunnel is carried out. During the excavation and support process, the face is grouted with advanced curtain grouting. Before the excavation of the ventilation duct middle step-2 tunnel, the foam concrete backfilling construction of the shield tunnel segments in the ventilation duct excavation area is completed and reaches the design strength requirements. At the same time, the steel structure support reinforcement measures inside the shield tunnel segments in the area adjacent to the ventilation duct excavation are completed. S4. When the shield tunnel segments are reached during the excavation process, the upper shield tunnel segments and foamed concrete are removed one by one. Initial support and temporary support construction are carried out in a timely manner. The ventilation duct middle step-2 tunnel is excavated to the end wall position, the end is sealed, and the middle gantry of the cross passage between middle step-1 and middle step-2 is constructed. The gantry provides a sufficient construction platform for the widened tunnel section, which is convenient for excavator and soil removal operations. The cross passage beams and plates at the corresponding positions are cut off and moved upward, and the gantry is installed. During the ventilation duct construction, the advanced support of the main line at the end of the widened tunnel is carried out as appropriate. After the advanced support of the main line is completed, the end of the widened tunnel is reinforced and the stress system of the cross passage wall is converted. The cross passage wall and the beams and plates at the corresponding positions are removed. The support bars inside the cross passage wall are cut off according to the design position of the arch of the widened tunnel. The steel ring bracket is installed and connected to the support bars inside the cross passage wall, so that the stress of the support bars inside the wall is transferred to the steel ring bracket. S5. The shaft is excavated to the design elevation at the bottom, sealed, and the retaining structure of the lower step of the ventilation duct is removed. Dense steel frame support is installed at the construction opening location. Then, the excavation and support construction of the lower step of the ventilation duct is carried out. When the shield tunnel segment is reached during the excavation, the lower shield tunnel segment and foam concrete are removed one by one. Initial support and temporary support construction are carried out in a timely manner. The lower step of the ventilation duct is excavated to the end wall position, sealed, the beams and plates at the corresponding positions are cut off, and the gantry is extended to complete the construction of the entire gantry. At the same time, the installation of the steel ring support at the tunnel end continues. After the construction is completed, the excavation construction of the main tunnel is carried out.

2. The method for constructing a subway station via tunnel boring machine (TBM) above a shield tunnel, as described in claim 1, is characterized in that: The excavation height of the upper step is 3m, and initial support is promptly implemented after the excavation is completed. Two steps are advanced, with 25 cubic meters per linear meter. The excavated material is directly backfilled to the bottom of the tunnel segment.

3. The method for constructing a subway station via tunnel boring machine (TBM) above a shield tunnel, as described in claim 1, is characterized in that: The middle step excavates the soil and rock outside the segment, with an excavation height of 2.62m, and erects a steel frame on the same side.

4. The method for constructing a subway station via tunnel boring machine (TBM) above a shield tunnel, as described in claim 3, is characterized in that: After the capping block of the middle step is loosened, it is removed by excavator. Then, the adjacent block near the tunnel sidewall is demolished, and the tunnel muck is transported directly away. After the middle step segments are broken, the steel frame on that side is erected in time. The upper middle step is constructed using the micro-step method, with a step spacing of 1.5m.

5. The method for constructing a subway station via tunnel boring machine (TBM) above a shield tunnel, as described in claim 4, is characterized in that: The lower step excavation height is 3.5m, and the construction is carried out on the left and right sides. The initial support of the left and right arch feet is longitudinally staggered by 5m. After the excavation is completed, the initial support construction is carried out in time. The tunnel muck is directly transported out of the tunnel.

6. The method for underground excavation of a subway station above a shield tunnel as described in claim 5, characterized in that: The upper, middle, and lower steps were excavated using an inverted arch method, with an excavation height of 1.145m. After the excavation was completed, the initial support was promptly closed into a ring, and plain concrete was backfilled.

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