Shield segment dismantling process for tunneling-first and station-second construction method

Abstract

The invention discloses a shield segment dismantling process for a tunnel-first and station-second construction method, and belongs to the technical field of tunnel construction, and the shield segment dismantling process comprises the following steps: S1, excavating a station foundation pit soil body to a steel support erection surface at a shield tunnel, and dismantling the upper half part of a shield segment affecting steel support erection; the steel supports at the shield tunnel are longitudinally arranged at intervals in the length direction of the shield tunnel; s2, steel supports are erected, and the soil body continues to be excavated downwards; and S3, after the station foundation pit soil body is excavated to the bottoms of the shield segments, the remaining shield segments are sequentially dismantled from top to bottom. According to the method, only the upper half pipe pieces locally influencing the supporting frame are removed, the whole-ring pipe pieces which are not influenced are reserved, the remaining whole-ring pipe pieces are used for guaranteeing overall stress, and the pipe pieces are removed after covering soil is excavated to the bottoms of the pipe pieces. Through the longitudinal integrity of the duct pieces, the safety of the foundation pit can be guaranteed when the constructed adjacent duct pieces in the station adopting the first-tunnel-later-station construction method are dismantled without additionally arranging a reinforcement measure in the duct pieces, and the investment is not increased and the construction period is not delayed.

Description

Technical Field

[0001] The invention belongs to the technical field of tunnel construction, and in particular relates to a shield segment removal process for a tunnel-first-station-later construction method. Background Art

[0002] As the main artery of urban transportation, urban rail transit has developed rapidly in recent years. The general construction method is to construct the station first, and then use the station as the starting or receiving end of the interval tunnel, use the shield method to construct the interval tunnel, and connect the stations through the tunnel.

[0003] During the actual construction process on site, it is often encountered that individual stations occupy land or pipelines are relocated or traffic is difficult, which makes it impossible to construct for a long time and causes delays in the construction period of the entire line. In order to ensure the construction period and minimize the occupation of municipal roads and the impact on citizens' lives, the stations before and after the delayed station are often used as the shield starting receiving end. The shield tunnel is first constructed to connect the two stations before and after, and then the temporary pipe segments within the scope of the delayed station are broken to construct the affected station.

[0004] During the construction process of the above-mentioned method, it is necessary to remove the temporary pipe segments within the station foundation pit. The removal of the pipe segments is an important part of the safety of the foundation pit construction. In the process of excavating the main foundation pit of the station, the covering soil is generally excavated from top to bottom in layers, and then supports are erected as needed until the excavation reaches the base. However, for stations with the tunnel-first-station-later method, the already constructed shield tunnel is located within the scope of the station excavation foundation pit. If the shield tunnel is also excavated and removed along with the soil in the foundation pit, the shield tunnel will become a non-circular stable structure due to the removal of some pipe segments, and will be squeezed and deformed by the soil around the tunnel, threatening the safety of the foundation pit.

[0005] In order to solve the above problems and make the retaining structure bear normal stress to ensure the safe excavation of the foundation pit, there are two existing solutions: sand blowing and grouting backfill in the temporary pipe segments within the station area (such as Figure 1 As shown in the figure), the soil pressure inside and outside the segments is offset, and the segments can be removed from top to bottom as the foundation pit is excavated; another method is to add temporary steel supports in the temporary segments within the station range (such as Figure 2 As shown in the figure), the internal support of the segment is used to resist the soil pressure outside the segment to ensure the safety after the segment is partially removed. However, the above schemes all require adding reinforcement measures in the temporary segment, and then removing the segment as the foundation pit is excavated, and finally gradually removing the backfill materials or supports in the segment as the segment is removed. The above construction process is time-consuming and labor-intensive, wastes project investment, and has an adverse effect on the construction period. Therefore, studying a new method for segment removal that is simple to construct and saves resources is a hot issue that the industry urgently needs to solve. Summary of the invention

[0006] In response to one or more of the above defects or improvement needs in the prior art, the present invention provides a shield segment removal process for the tunnel-first-station-later construction method, which can ensure the safety of the foundation pit when removing the constructed segments in the station of the tunnel-first-station-later construction method without adding reinforcement measures inside the segments.

[0007] To achieve the above object, the present invention provides a shield segment removal process for a tunnel-first-station-later construction method, comprising the following steps: S1 excavates the station foundation pit soil to the steel support erection surface at the shield tunnel, removes the upper part of the shield segment that affects the steel support erection, retains the lower part of the shield segment that does not affect the steel support erection and the whole ring segment that does not affect the steel support erection; the steel supports at the shield tunnel are arranged longitudinally at a set distance in the length direction of the shield tunnel; S2 sets up steel supports and continues to excavate the soil downwards; S3 After the station foundation pit soil is excavated to the bottom of the shield segment, the remaining shield segments are removed from top to bottom.

[0008] As a further improvement of the present invention, the steel supports are arranged corresponding to the middle of a ring of shield segments, and the steel supports are arranged at intervals of a ring of shield segments, that is, the longitudinal distance between the steel supports is the same as the width of two rings of shield segments; The scope of shield segment removal is the portion of the shield segment located above the steel support erection surface at intervals of one ring along the tunnel direction.

[0009] As a further improvement of the present invention, the steel support erection surface at the shield tunnel is located within the height range of the shield tunnel, the steel support transversely passes through the range of shield segment removal, and both ends are supported on the station foundation pit.

[0010] As a further improvement of the present invention, the double-track shield tunnels are symmetrically arranged side by side and located in the same excavated station pit; each ring of the double-track shield tunnel segments corresponds one to one on the same cross-section, and when the station pit is excavated to the excavation surface where the double-track shield segments affect the support installation, the upper half of the double-track shield segments that affect the steel support installation are demolished at the same time.

[0011] As a further improvement of the present invention, the steel support at the shield tunnel passes through the double-track shield tunnels at the same time, and both ends are supported on the station foundation pits on both sides of the shield tunnel.

[0012] As a further improvement of the present invention, in step S1, when removing the upper half of the shield segment that affects the installation of the steel support, the connecting bolts between the segments that affect the installation of the steel support are removed from top to bottom inside the shield segment ring, and the free segments are lifted and disassembled after the bolts are removed.

[0013] As a further improvement of the present invention, in step S2, when the steel supports are erected between the full ring of segments, it is necessary to prevent the steel supports from colliding with the retained segments during the erection; when the soil is continued to be excavated downward, the soil on both sides of the segments is excavated symmetrically, and excavated in layers and sections along the longitudinal direction of the foundation pit.

[0014] As a further improvement of the present invention, in step S3, when removing the remaining segments from top to bottom, first remove the upper half of the entire ring of segments from top to bottom inside the shield segment ring, and then remove the remaining lower half of the segments from top to bottom.

[0015] In general, the above technical solution conceived by the present invention has the following beneficial effects compared with the prior art: (1) The shield segment removal process for the tunnel-first-station-later construction method of the present invention only removes the upper half of the segment that partially affects the support erection, retains the whole ring of segments that are not affected, and uses the remaining whole ring of segments to ensure the overall force. After the backfill is excavated to the bottom of the segment, the segment is removed again. Through the longitudinal integrity of the segment, the safety of foundation pit excavation is ensured without affecting the support erection. Compared with the methods of sand blowing grouting backfilling and adding temporary steel support in the segment in the prior art, there is no need to add reinforcement measures in the segment, and the safety of the foundation pit can be guaranteed when removing the temporary segments constructed in the station of the tunnel-first-station-later construction method, without increasing investment and delaying the construction period.

[0016] (2) The shield segment removal process for the tunnel-first-station-later construction method of the present invention is simple to operate, has good feasibility, meets the safety requirements of the regulations, and significantly reduces the cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of sand blowing and grouting backfilling in a temporary pipe segment within a station area in the prior art; Figure 2 A schematic diagram of adding temporary steel support within a temporary pipe segment within a station area in the prior art; Figure 3 It is a schematic diagram of the plane removal range of the shield segment after excavation to the support erection surface according to an embodiment of the present invention; Figure 4 It is the vertical removal range of the shield segment after excavation to the support erection surface in the embodiment of the present invention; Figure 5 This is a schematic diagram of excavation to the bottom of the segment according to an embodiment of the present invention.

[0018] In all the drawings, the same reference numerals represent the same technical features, specifically: 1. pipe segment; 2. steel support. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0020] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0021] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying 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 the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0022] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0023] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0024] As a preferred embodiment of the present invention, the present invention provides a shield segment removal process for a tunnel-first-station-later construction method, comprising the following steps: (1) Excavate the station foundation pit to the steel support erection surface at the shield tunnel, and remove the upper part of the shield segment that affects the steel support erection; the steel supports at the shield tunnel are arranged longitudinally at a set distance in the length direction of the shield tunnel; In the tunnel-first-station-later construction method, temporary segments are arranged along the length of the tunnel, and support is provided as the station foundation pit is excavated until the excavation surface where the temporary shield segments affect the installation of steel supports is reached. Since the steel supports are arranged longitudinally at a set distance in the length direction of the shield tunnel, the installation of steel supports is actually affected only by the segments where the steel supports are set. Therefore, in step (1), the soil is excavated normally according to the station foundation pit construction method in the prior art, and after excavation to the installation elevation of the steel supports at the shield segments, the upper half of the shield segments that affect the installation of the steel supports are removed, and the lower half of the shield segments that do not affect the installation of the steel supports and the full ring of segments that do not affect the installation of the steel supports are retained.

[0025] In a preferred embodiment, the scope of shield segment removal in step (1) is the portion of shield segments spaced one ring apart in the length direction of the tunnel that is located above the steel support erection surface. In the embodiment of the present invention, the steel supports at the shield tunnel are arranged in the middle of a ring of shield segments, and the steel supports are arranged one ring apart from the shield segments, that is, the longitudinal distance between the steel supports (the distance along the length direction of the tunnel) is the same as the width of the two rings of shield segments (the size along the length direction of the tunnel). In this way, only the upper half of the spaced ring of segments that affects the steel support erection needs to be removed.

[0026] See also Figure 3 and Figure 4 , Figure 3 This is a schematic diagram of the planar removal range of the shield segments after excavation to the support erection surface according to an embodiment of the present invention, wherein the solid area is filled with the planar removal range of the segments, and the cross-hatch lines are filled with the planar range of the remaining shield segments. Figure 4 This is a schematic diagram of the vertical demolition range of the shield segments after excavation reaches the steel support erection surface, where the solid area is the vertical demolition range of the segments.

[0027] Since the steel support erection surface is located within the height range of the shield tunnel, and the steel support passes through the pipe segment horizontally, the semi-ring pipe segment below the steel support will not affect the erection of the steel support, and only the semi-ring pipe segment above the steel support needs to be removed. In the present invention, since the whole ring of pipe segments that do not affect the erection of the steel support are retained during the removal process, and only the upper half of the interval pipe segment is removed, it can be considered that the lower half of the removed pipe segment is supported on the whole ring of pipe segments, and the horizontal connection between the pipe segments is transformed into longitudinal force, so that the force stability after the pipe segment is broken will not be affected, and the safety of foundation pit excavation is ensured.

[0028] Further Figure 3 and Figure 4 As shown, in this embodiment, the temporary shield tunnels of the double lines are symmetrically arranged side by side and located in the same excavated station foundation pit. The steel supports pass through the temporary shield tunnels of the double lines at the same time, and the two ends are supported on the station foundation pits on both sides of the temporary shield tunnels. Therefore, in this embodiment, each ring of the temporary shield tunnel segments of the double lines corresponds to each other on the same cross section, so that when the station foundation pit is excavated to the excavation surface where the double-line temporary shield segments affect the support erection, the corresponding segments of the double-line temporary shield segments are removed at the same time.

[0029] For example, in a specific embodiment, the subway station foundation pit is about 200m long, the width of each ring of shield segments in the subway station is 1.5m, and they are arranged adjacent to each other in the longitudinal direction of the subway station tunnel. The steel supports of the station foundation pit are arranged at intervals of 3.0m in the longitudinal direction, and the steel supports are arranged centrally in the width direction of the shield segments, that is, the setting position of the steel supports corresponds to the middle of the width direction of the corresponding segments, and the distance between two adjacent steel supports (3.0m) is the same as the width of the two segments (1.5*2m).

[0030] Specifically, when the upper half of the shield segments above the steel support erection surface are removed after the soil in the foundation pit is excavated to the steel support erection elevation, the connecting bolts between the shield segments that affect the steel support erection are removed from top to bottom inside the shield segment ring, and the free segments are lifted and disassembled after the bolts are removed. During the dismantling process, attention should be paid to protecting the segments for reuse.

[0031] It is understandable that the vertical removal range of the segments does not have to be strictly in accordance with Figure 4 The semicircular control shown in the figure only requires removing the pipe segments that affect the steel support frame from the connecting bolts to ensure that the steel support can be erected normally after the pipe segments are removed.

[0032] (2) Set up steel supports and continue to excavate the soil downwards; Specifically, during construction, after removing some of the segments, the steel supports are erected in the narrow space between the remaining full ring segments. This is different from the open working surface of a general station, so it is necessary to strengthen the construction accuracy control to prevent the steel supports from colliding with the remaining segments during erection. After the steel supports are erected, the force of the retaining structure in the station foundation pit is guaranteed, and the soil can be excavated downwards. The soil on both sides of the segments should be excavated symmetrically to prevent bias. Preferably, the excavation is carried out in layers and sections along the longitudinal direction of the foundation pit, and the excavation thickness of each layer of soil is preferably less than 2m.

[0033] (3) After the station foundation pit soil is excavated to the bottom of the shield segment, the remaining shield segments are removed from top to bottom; After the station foundation pit soil is excavated to the bottom of the shield segment, the shield segment is no longer affected by horizontal forces, and the segments can be removed from top to bottom. Figure 5The figure shows the vertical removal range of the shield segments after the soil in the station foundation pit is excavated to the bottom of the shield segments. The figure is filled with the vertical removal range of the shield segments. In this process, the plane range can be removed, and the vertical removal is from top to bottom.

[0034] Specifically, when removing the remaining segments from top to bottom, the upper half of the entire ring of shield segments retained in the early stage shall be removed from top to bottom inside the shield segment ring according to the aforementioned method, and the connecting bolts between the segments shall be removed before lifting and disassembling the free segments; then all the remaining lower half segments shall be removed from top to bottom in turn. During the dismantling process, attention shall be paid to the protection of the segments for reuse.

[0035] The shield segment removal process for the tunnel-first-station-later construction method of the present invention is suitable for shield tunnels that adopt the tunnel-first-station-later construction method (i.e., shield tunnels that are constructed first by using the two stations before and after the station that cannot be constructed as the shield starting and receiving ends). After the affected station meets the construction conditions, the station foundation pit is excavated, and the support is provided as the excavation progresses until the excavation surface where the temporary shield segment affects the installation of steel supports is reached. Along the length direction of the tunnel, only the upper half of the segments that affect the installation of steel supports are removed, and the remaining segments are retained in a whole ring; steel supports are then installed to ensure that the retaining structure is stressed, and then the soil is excavated downward to the bottom of the segments; finally, the remaining segments are removed from top to bottom in sequence, and the removal of the tunnel segments of the tunnel-first-station-later construction method is completed. After further excavation of the soil to the base, the subsequent construction of the main structure of the station can be carried out.

[0036] The shield segment removal process for the tunnel-first-station-later construction method of the present invention only removes the upper half of the segments that partially affect the steel support installation, retains the full ring of segments that are not affected, and uses the remaining full ring of segments to ensure the overall force, and then removes them after the soil is excavated to the bottom of the segments. Due to the longitudinal integrity of the segments, there is no need to add reinforcement measures inside the segments, and the safety of foundation pit excavation is guaranteed without affecting the support installation. In a specific application example, the Yixinqiao Station of Kunming Rail Transit Line 5 adopts the tunnel-first-station-later construction method. The station applies the patented solution to remove the shield segments. Through testing, the shield segment removal process of the present invention can meet the requirements of foundation pit excavation and save a lot of manpower and material costs.

[0037] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A shield segment removal process for the tunnel-first-station-later construction method, characterized in that: The steps include: S1 excavates the station foundation pit soil to the steel support erection surface at the shield tunnel, removes the upper part of the shield segment that affects the steel support erection, retains the lower part of the shield segment that does not affect the steel support erection and the whole ring segment that does not affect the steel support erection; the steel supports at the shield tunnel are arranged longitudinally at a set distance in the length direction of the shield tunnel; S2 sets up steel supports and continues to excavate the soil downwards; S3 After the station foundation pit soil is excavated to the bottom of the shield segment, the remaining shield segments are removed from top to bottom.

2. The shield segment removal process for the tunnel-first-station-later construction method according to claim 1 is characterized in that: The steel supports are arranged corresponding to the middle of a ring of shield segments, and the steel supports are arranged at intervals of one ring of shield segments, that is, the longitudinal distance between the steel supports is the same as the width of two rings of shield segments; The scope of shield segment removal is the portion of the shield segment located above the steel support erection surface at intervals of one ring along the tunnel direction.

3. The shield segment removal process for the tunnel-first-station-later construction method according to claim 1 is characterized in that: The steel support erection surface at the shield tunnel is located within the height range of the shield tunnel. The steel support transversely passes through the range of shield segment removal, and both ends are supported on the station foundation pit.

4. The shield segment removal process for the tunnel-first-station-later construction method according to any one of claims 1 to 3, characterized in that: The double-track shield tunnels are arranged symmetrically side by side in the same excavated station pit; each ring of the double-track shield tunnel segments corresponds one to one on the same cross-section. When the station pit is excavated to the excavation surface where the double-track shield segments affect the support installation, the upper half of the double-track shield segments that affect the steel support installation are demolished at the same time.

5. The shield segment removal process for the tunnel-first-station-later construction method according to claim 4 is characterized in that: The steel supports at the shield tunnel pass through the double-track shield tunnels at the same time, and both ends are supported on the station foundation pits on both sides of the shield tunnel.

6. The shield segment removal process for the tunnel-first-station-later construction method according to any one of claims 1-3 or 5, characterized in that: In step S1, when removing the upper part of the shield segment that affects the installation of the steel support, the connecting bolts between the segments that affect the installation of the steel support are removed from top to bottom inside the shield segment ring, and the free segments are lifted and disassembled after the bolts are removed.

7. The shield segment removal process for the tunnel-first-station-later construction method according to any one of claims 1 to 3 or 5, characterized in that: In step S2, when the steel supports are erected between the full ring of segments, it is necessary to prevent the steel supports from colliding with the retained segments during the erection; when the soil is continued to be excavated downward, the soil on both sides of the segments is excavated symmetrically, and excavated in layers and sections along the longitudinal direction of the foundation pit.

8. The shield segment removal process for the tunnel-first-station-later construction method according to any one of claims 1-3 or 5, characterized in that: In step S3, when removing the remaining segments from top to bottom, first remove the upper half of the entire ring of segments from top to bottom inside the shield segment ring, and then remove the remaining lower half of the segments from top to bottom.

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