Construction method and construction structure for non-span-reducing construction of super-large-section shallow-buried subway station

Abstract

The application discloses a non-span-reducing construction method and construction structure for a super-large-section shallow-buried subway station, and belongs to the technical field of underground building engineering.Compared with a traditional arch cover method, the non-span-reducing construction method is different in that the traditional primary support arch cover method is optimized, a surface cable supporting structure is installed on the ground, a temporary vertical support structure in the construction process of the primary support arch cover method is cancelled, the influence of the dismantling process on surrounding rock and the supporting structure is avoided, and the non-span-reducing construction is realized in a true sense.Under the premise of ensuring construction safety, the demand of mechanized construction for a large operation space is met, and engineering efficiency and quality are improved.In addition, the top end of the surface cable is connected with a supporting plate through an anchor device, the surface cable can be prestressed through the anchor device, the tension size can be adjusted, and construction safety is ensured;and the anchor device is detachable, the supporting plate can be recycled and reused, and good economic benefits are achieved.

Description

Technical Field

[0001] This invention belongs to the field of underground construction engineering technology, specifically relating to a non-span reduction construction method and construction structure for ultra-large cross-section shallow buried subway stations. Background Technology

[0002] With the continuous development of my country's economy, the demand for underground space development is growing rapidly, and subway and other rail transit have become an important direction for the modernization of urban construction in my country. my country has a vast territory and extremely complex geological conditions. Many urban areas have shallow bedrock, such as Qingdao, Dalian, and Xiamen, which have typical soft upper and hard lower strata. The main structures of many large-span subway stations are located in these areas. To avoid the problems of pipeline relocation and traffic congestion often encountered by conventional cut-and-cover methods, the use of the tunneling method is becoming more and more frequent, and research on the tunneling method is becoming more in-depth and perfect.

[0003] Currently, existing methods for excavating large-span underground structures using the cut-and-cover method include the double-sided wall pilot tunnel method, the tunnel-pile method, and the initial support arch cover method, and these methods have been widely applied and documented in numerous engineering projects. However, the basic principle of these methods is to reduce the span through structures such as columns, piles, or temporary vertical supports. In today's trend towards mechanized and rapid construction, the use of columns, piles, and temporary vertical supports will more or less affect the demand for large working spaces for heavy machinery. Summary of the Invention

[0004] The purpose of this invention is to provide a non-reduced span construction method and construction structure for ultra-large cross-section shallow buried subway stations. By installing a surface cable support structure on the ground surface, the temporary vertical support structure in the initial support arch method construction process is eliminated, thereby increasing the working space, reducing construction difficulty, and improving construction efficiency.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A non-span reduction construction method for ultra-large cross-section shallow-buried subway stations includes the following steps:

[0007] Step 1: Accurately locate the station centerline on the ground, level the ground, mechanically drill holes, and pre-install and construct the surface cable support structure; the surface cable support structure includes a support plate fixed on the ground and several surface cables vertically fixed below the support plate; the top of the surface cable passes through the support plate and is fixedly connected to the support plate, and the bottom of the surface cable is fixed with a connecting plate;

[0008] Step 2: Excavate the upper guide tunnel on the left side of the station arch to expose the bottom end of the pre-embedded surface cable, and then construct the initial support arch cover in this area;

[0009] Step 3: Excavate the remaining part of the station arch using the CD method and complete the construction of the remaining initial support arch cover. According to the CD method, the station arch is divided into four parts: the left upper guide tunnel, the left lower guide tunnel, the right upper guide tunnel, and the right lower guide tunnel. Excavation is carried out sequentially in the order of the left upper guide tunnel, left lower guide tunnel, right upper guide tunnel, and right lower guide tunnel. The excavation depth is controlled reasonably according to the geological conditions. Preferably, the left and right ends of the initial support arch cover have large arch foot connecting beams, which are cast using a molded casting method.

[0010] Step 4: Under the support of the initial arch cover, excavate the lower rock mass of the station and promptly construct the initial support for the lower side walls and the initial support for the invert arch; preferably, the excavation of the lower rock mass of the station adopts the step method for segmented construction, strictly controlling the step length and blasting parameters to reduce disturbance.

[0011] Step 5: Construct the secondary lining of the lower station arch;

[0012] Step 6: Construct the secondary lining of the side walls and the secondary lining of the arch;

[0013] Step 7: After the secondary lining of the invert arch, the secondary lining of the side walls, the secondary lining of the arch crown, and the surrounding rock have stabilized, separate the surface cables and support plates, recover the support plates, backfill the soil, and restore the road surface.

[0014] The non-span reduction construction method for ultra-large cross-section shallow buried subway stations provided by this invention utilizes the traditional initial support arch cover method and optimizes it, eliminating the installation and removal of temporary vertical supports, reducing disturbance, and providing a wider working space.

[0015] In steps 2 and 3 above, the initial support arch construction process is as follows: after the bottom end of the surface cable is exposed, the surrounding rock is immediately sealed with shotcrete, then the grid steel frame is installed, and the grid steel frame is anchored to the bottom end of the surface cable through the connecting plate to form an integral whole. Then, shotcrete is sprayed to seal it, thus completing the construction of the initial support arch.

[0016] This invention also provides a subway station construction structure constructed using the aforementioned non-span reduction construction method for ultra-large cross-section shallow-buried subway stations, comprising an internal main structure and a surface cable-stayed support structure, wherein:

[0017] The top of the main internal structure of the station is an arch structure, which includes an initial support arch cover and a secondary arch lining arranged on the initial support arch cover from the outside to the inside; the bottom of the main internal structure of the station includes an initial support for the invert arch and a secondary arch lining arranged on the initial support for the invert arch from the outside to the inside; the two sides of the main internal structure of the station are symmetrical side wall structures, which include an initial support for the side wall and a secondary side wall lining arranged on the initial support for the side wall from the outside to the inside; the secondary arch lining, the secondary side wall lining, and the secondary arch lining are connected to form an integral secondary lining structure;

[0018] The surface cable support structure includes a support plate fixed to the ground and several surface cables vertically fixed below the support plate. The top ends of the surface cables pass through and are fixedly connected to the support plate, while the bottom ends of the surface cables are fixed with connecting plates. These connecting plates are located at the bottom of the initial arch and provide anchoring for the arch. In this invention, the surface cable support structure provides upward support to the initial arch through the connecting plates, thus maintaining the structural stability of the arch.

[0019] In a further embodiment, the top of the surface cable is connected to the support plate via anchors. The anchors allow for prestressing of the surface cable and adjustment of the tension, ensuring construction safety. Furthermore, the anchors are detachable, enabling the support plate to be recycled and reused, resulting in good economic benefits. The surface cable is made of high-tensile-strength, low-elongation construction cable. More preferably, the support plate comprises a steel plate and an I-beam fixed within the steel plate. Specifically, the I-beam is a high-strength, high-rigidity I-shaped steel plate beam; both the support plate and the connecting plate are made of high-strength, high-rigidity steel.

[0020] The beneficial effects of this invention are:

[0021] This invention optimizes the traditional initial support arch method by installing a surface cable support structure on the ground, eliminating the need for temporary vertical supports during construction. This avoids the impact of dismantling supports on the surrounding rock and support structure, achieving true non-span reduction. While ensuring construction safety, it meets the demand for large working space in mechanized construction, improving project efficiency and quality. Furthermore, the support plates in the surface cable support structure are reusable, reducing construction costs and resulting in significant economic benefits. Attached Figure Description

[0022] Figure 1 The subway station construction structure of the present invention.

[0023] Figure 2 This is a front view of the surface cable support structure of the present invention.

[0024] Figure 3 This is a schematic diagram of the connection between the surface cable support structure and the initial support arch of the present invention.

[0025] Figure 4 This is a schematic diagram of the excavation sequence of the present invention.

[0026] Attached reference numerals: 1-Initial support arch cover, 2-Initial support of side walls, 3-Initial support of invert arch, 4-Secondary lining of invert arch, 5-Secondary lining of side walls, 6-Secondary lining of arch crown, 7-Surface cable, 8-I-beam, 9-Steel plate, 10-Connecting plate, 11-Anchorage, 12-Grid steel frame. Detailed Implementation

[0027] The present invention will be further described below with reference to the accompanying drawings and embodiments, so that those skilled in the art can better understand and implement the present invention, but the embodiments are not intended to limit the present invention.

[0028] A subway station construction structure, reference Figures 1 to 3 This includes the station's internal main structure and the surface cable-stayed support structure, among which:

[0029] The top of the main internal structure of the station is an arch structure, which includes, from the outside to the inside, an initial support arch cover 1 and an arch secondary lining 6 laid on the initial support arch cover; the bottom of the main internal structure of the station includes, from the outside to the inside, an invert arch initial support 3 and an invert arch secondary lining 4 laid on the invert arch initial support; the two sides of the main internal structure of the station are symmetrical side wall structures, which include, from the outside to the inside, side wall initial support 2 and side wall secondary lining 5 laid on the side wall initial support; the arch secondary lining 6, the side wall secondary lining 5 and the invert arch secondary lining 4 are connected to form an integral secondary lining structure;

[0030] The surface cable support structure includes a support plate fixed to the ground and several surface cables 7 vertically fixed below the support plate. The top ends of the surface cables 7 pass through the support plate and are fixedly connected to it. The bottom ends of the surface cables are fixed with connecting plates 10, which are located at the bottom of the initial support arch 1 and provide anchoring for the initial support arch 1. Preferably, the top ends of the surface cables 7 are connected to the support plate via anchors 11. The support plate includes a steel plate 9 and an I-beam 8 fixed within the steel plate 9.

[0031] A non-span reduction construction method for ultra-large cross-section shallow-buried subway stations includes the following steps:

[0032] Step 1: Install the surface cable support structure: First, accurately locate the station centerline on the ground, level the ground, dig the pits needed to place the support plates, and mechanically drill holes along the station centerline to below the designed burial depth; then assemble the I-beam 8 and steel plate 9; then insert the surface cable 7 into the drilled hole, with an insertion length about 50cm greater than the burial depth, and leave a length of 20-30cm at the top of the surface cable, and anchor the top of the surface cable to the high-rigidity steel plate 9 with anchors.

[0033] Step 2: Excavate the upper guide tunnel on the left side of the station arch to expose the bottom end of the pre-embedded surface cable. Immediately afterward, spray concrete to seal the surrounding rock. Then, install the grid steel frame 12 and anchor the grid steel frame 12 to the bottom end of the surface cable 7 through the connecting plate 10 to form a whole. Then, spray concrete to seal the initial support arch cover. During the subsequent construction process, increase the monitoring of the arch. If necessary, the tension can be adjusted through the bolts at the top of the surface cable to ensure the safety of the arch.

[0034] Step 3: Reference Figure 4Following the CD method, the station arch was divided into four parts: the left upper guide tunnel, the left lower guide tunnel, the right upper guide tunnel, and the right lower guide tunnel. Excavation proceeded sequentially in the order of the left upper guide tunnel, left lower guide tunnel, right upper guide tunnel, and right lower guide tunnel. The excavation depth was controlled according to geological conditions. The remaining portion of the station arch was excavated, and the remaining initial support arch was constructed. Furthermore, the initial support arch 1 has a large arch foot connecting beam, cast using a molded casting method. The large arch foot of the initial support arch is supported by rock strata, and its thickness is much greater than that at the arch crown and waist, which improves the support strength of the initial support arch and enhances its safety.

[0035] Step 4: Reference Figure 4 Under the support of the initial arch cover 1, the lower rock mass of the station is excavated using the bench method. The bench length and blasting parameters are strictly controlled by combining mechanical excavation and controlled blasting to reduce disturbance. The initial support 2 of the lower side wall and the initial support 3 of the invert arch are constructed in a timely manner.

[0036] refer to Figure 4 The construction of the secondary lining 4 (invert arch lining 4), secondary lining 5 (side wall lining 5), and secondary lining 6 (arch crown lining 6) in steps 5 and 6 is completed sequentially. These components are then connected to form an integral secondary lining structure. Preferably, the thickness of the secondary lining 4 (invert arch lining 4) is greater than that of the secondary lining 5 (side wall lining 5) and the secondary lining 6 (arch crown lining 6). Furthermore, a waterproof layer is provided on the exterior of the secondary lining structure to prevent water seepage and invert arch bulging, which could affect construction safety and subsequent operational safety.

[0037] Step 7: After the secondary lining structure and surrounding rock of the station have stabilized, remove the anchors at the top of the surface cables, cut off the excess part at the top of the surface cables, remove and recycle the I-beams 8 and steel plates 9, backfill the soil and restore the road surface.

[0038] In summary, this invention is an optimization of the traditional initial support arch method. By adopting a recyclable and reusable surface cable support structure, the temporary vertical support structure of the initial support arch method is eliminated, avoiding the impact of the dismantling process on the surrounding rock and support structure. This achieves true non-span reduction, providing ample working space for mechanized construction while ensuring construction safety, reducing construction difficulty, improving construction efficiency, and also offering certain economic benefits.

[0039] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. All other embodiments without inventive effort, and any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention, should be included within the scope of protection of the present invention.

Claims

1. A non-span reduction construction method for ultra-large cross-section shallow-buried subway stations, characterized in that: The method comprises the following steps: Step 1, accurately positioning the station center line on the ground, arranging the ground, mechanically drilling, pre-installing and constructing the surface cable support structure; the surface cable support structure comprises a support plate fixed on the ground and a plurality of surface cables vertically fixed below the support plate; the top end of the surface cable penetrates the support plate and is fixedly connected with the support plate, and the bottom end of the surface cable is fixedly connected with a connecting plate; the top end of the surface cable is connected with the support plate through an anchor device, and the surface cable is pre-stressed through the anchor device; Step 2, excavate the left upper guide hole of the station arch part, expose the pre-buried bottom end of the surface cable, and then construct the initial support arch cover of the region; Step 3, excavate the remaining part of the station arch part by CD method, and complete the construction of the remaining initial support arch cover; Step 4, under the support of the initial support arch cover, excavate the lower rock mass of the station, and timely construct the initial support of the lower side wall and the initial support of the inverted arch; Step 5, construct the second lining of the lower station inverted arch; Step 6, construct the second lining of the side wall and the second lining of the arch top; Step 7, after the second lining of the inverted arch, the second lining of the side wall, the second lining of the arch top and the surrounding rock are stable, separate the surface cable and the support plate, recycle the support plate, backfill the soil and restore the road surface; In steps 2 and 3, the construction process of the initial support arch cover is as follows: after the bottom end of the surface cable is exposed, the surrounding rock is immediately closed by initial spraying of concrete, then the grid steel frame is installed and anchored with the bottom end of the surface cable through the connecting plate, forming an integral whole, and then the concrete is sprayed to close, that is, the construction of the initial support arch cover is completed.

2. The non-reducing span construction method of an ultra-large cross-section shallow-buried subway station according to claim 1, characterized in that: The left and right ends of the initial support arch cover have large arch foot beams, which are cast by mold casting.

3. The non-reducing span construction method of an ultra-large cross-section shallow-buried subway station according to claim 1, characterized in that: In step 3, according to the CD method, the station arch part is divided into left upper guide hole, left lower guide hole, right upper guide hole and right lower guide hole, and is excavated in the order of left upper guide hole, left lower guide hole, right upper guide hole and right lower guide hole.

4. The non-reducing span construction method of an ultra-large cross-section shallow-buried subway station according to claim 1, characterized in that: In step 4, the excavation of the lower rock mass of the station is constructed by step method, the length of the step is strictly controlled, and the blasting parameters are controlled to reduce disturbance.

5. A subway station construction structure formed by the non-reducing span construction method for a super-large cross-section shallow-buried subway station according to claim 1, characterized in that: The method comprises the station internal main structure and the surface cable support structure, wherein: The top of the station internal main structure is an arch structure, which comprises an initial support arch cover and an arch top second lining arranged on the initial support arch cover from outside to inside; the bottom of the station internal main structure comprises an inverted arch initial support and an inverted arch second lining arranged on the inverted arch initial support from outside to inside; the two sides of the station internal main structure are symmetrical side wall structures, which comprise a side wall initial support and a side wall second lining arranged on the side wall initial support from outside to inside; the arch top second lining, the side wall second lining and the inverted arch second lining are connected to form an integral secondary lining structure; The surface cable support structure comprises a support plate fixed on the ground and a plurality of surface cables vertically fixed below the support plate; the top end of the surface cable penetrates the support plate and is fixedly connected with the support plate, and the bottom end of the surface cable is fixedly connected with a connecting plate, which is located at the bottom of the initial support arch cover and plays an anchoring role on the initial support arch cover.

6. The subway station construction structure according to claim 5, characterized by: The top end of the surface cable is connected with the support plate through an anchor device.

7. The subway station construction structure according to claim 6, characterized by: The support plate comprises a steel plate and an I-beam fixed in the steel plate.

8. The subway station construction structure according to claim 5, characterized by: The surface layer of the integral secondary lining structure is provided with a waterproof layer.

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