CN113669084B - Lake facies deposition weak stratum subway tunnel-first and station-last segment dismantling method - Google Patents
Lake facies deposition weak stratum subway tunnel-first and station-last segment dismantling method Download PDFInfo
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- CN113669084B CN113669084B CN202111113196.1A CN202111113196A CN113669084B CN 113669084 B CN113669084 B CN 113669084B CN 202111113196 A CN202111113196 A CN 202111113196A CN 113669084 B CN113669084 B CN 113669084B
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- 238000000034 method Methods 0.000 title claims abstract description 42
- 230000008021 deposition Effects 0.000 title claims abstract description 13
- 208000035126 Facies Diseases 0.000 title claims abstract description 9
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 41
- 239000010959 steel Substances 0.000 claims abstract description 41
- 238000007664 blowing Methods 0.000 claims abstract description 29
- 238000010276 construction Methods 0.000 claims abstract description 27
- 239000004576 sand Substances 0.000 claims abstract description 19
- 230000003014 reinforcing effect Effects 0.000 claims abstract description 15
- 238000005488 sandblasting Methods 0.000 claims abstract description 10
- 239000002689 soil Substances 0.000 claims abstract description 7
- 238000009412 basement excavation Methods 0.000 claims description 45
- 229910001294 Reinforcing steel Inorganic materials 0.000 claims description 15
- 239000004568 cement Substances 0.000 claims description 9
- 238000013461 design Methods 0.000 claims description 9
- 239000002002 slurry Substances 0.000 claims description 9
- 230000000694 effects Effects 0.000 claims description 7
- 230000002787 reinforcement Effects 0.000 claims description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 4
- 239000003469 silicate cement Substances 0.000 claims description 3
- 239000002893 slag Substances 0.000 claims description 3
- 230000000903 blocking effect Effects 0.000 description 8
- 230000005641 tunneling Effects 0.000 description 6
- 230000002457 bidirectional effect Effects 0.000 description 4
- 238000006073 displacement reaction Methods 0.000 description 3
- 238000012544 monitoring process Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 1
- 239000003673 groundwater Substances 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012856 packing Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D11/00—Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
- E21D11/04—Lining with building materials
- E21D11/12—Temporary supports for use during building; Accessories
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D17/00—Excavations; Bordering of excavations; Making embankments
- E02D17/02—Foundation pits
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D29/00—Independent underground or underwater structures; Retaining walls
- E02D29/04—Making large underground spaces, e.g. for underground plants, e.g. stations of underground railways; Construction or layout thereof
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D3/00—Improving or preserving soil or rock, e.g. preserving permafrost soil
- E02D3/12—Consolidating by placing solidifying or pore-filling substances in the soil
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/20—Hydro energy
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Abstract
The invention discloses a lake facies deposition weak stratum subway tunnel-first and station-last segment dismantling method, which comprises the following steps: 1. adding a shield inner steel reinforcing structure to a shield segment outside the station; 2. making a sand-blowing grouting plugging wall for the segments to be removed; 3. filling fine sand into the shield tunnel in a pressure blowing and filling mode; 4. excavating earthwork below the center line of the shield segment; 5. removing the top shield segment; 6. erecting a temporary support; 7. digging out the rest part of the segment and constructing a shield ring beam; 8. and continuously excavating to the bottom of the foundation pit. According to the invention, the section steel support and the longitudinal tensioning device are applied to the outer pipe sheet of the station, and the sand blasting grouting treatment is carried out on the removed pipe sheet, so that the problem that the removed pipe sheet cannot form a complete annular stress system after the partial pipe sheet is removed, so that the soil pressure of a passive area of a foundation pit is insufficient and the deformation of a diaphragm wall is overlarge is solved, and the method is particularly suitable for the pipe sheet removing construction of a tunnel-first station and a tunnel-last station of a subway in a weak stratum deposited in a lake.
Description
Technical Field
The invention belongs to the technical field of tunnel-first and station-last segment removal of a lake-phase-deposition weak stratum subway, and particularly relates to a tunnel-first and station-last segment removal method of a lake-phase-deposition weak stratum subway.
Background
The conventional construction process of subway construction is to construct an enclosure structure of an advanced driving station and a part of main body structure, and then to construct a tunnel after the station has the conditions of shield tunneling machine descending, entering and passing by, and the like, namely, the station is followed by tunneling. The station main body can be fully utilized as a shield site by the station-first tunneling, so that the repeated construction workload is reduced. However, in actual construction, due to the problems of traffic evacuation, surrounding building structures, pipeline disassembly and construction period, the station cannot normally construct, and the subsequent shield tunnel cannot construct. In order to avoid influencing the construction period, the construction method of firstly tunneling and then standing is provided, namely, the tunnel is firstly shield-constructed, the station construction is carried out on the basis of the established tunnel, the subway construction quality is improved by firstly tunneling and then standing, the construction period is shortened, and the problem that the traffic is influenced due to the fact that the open cut method occupies the lane is solved. For how to effectively and safely dismantle the shield segment, the key problem in the construction of the first-tunneling and the second-standing is that the shield segment is safely dismantled.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides a method for removing segments of a tunnel-first and a station-later subway in a weak stratum deposited on a lake, which is used for carrying out sand blasting grouting treatment on removed segments by applying a section steel support and a longitudinal tensioning device to outer tubular segments of a station, solves the problems that after part of segments are removed, the removed segments cannot form a complete annular stress system, so that the soil pressure of a passive area of a foundation pit is insufficient and the deformation of a diaphragm wall is overlarge, and is particularly suitable for segment removing construction of the tunnel-first and the station-later subway in the weak stratum deposited on the lake, and is convenient to popularize and use.
In order to solve the technical problems, the invention adopts the following technical scheme: a lake facies deposition weak stratum subway tunnel-first and station-last segment dismantling method is characterized by comprising the following steps:
step one, adding a shield inner section steel reinforcing structure to a shield segment outside a station: reinforcing all shield segments in the ring 20 from the station by using the section steel in a 'well' -shape, so as to ensure the safety of the shield segments;
step two, performing sand-blasting grouting on the pipe piece to be removed to form a plugging wall: setting a sand-blowing grouting plugging wall at intervals of 3 spans;
filling fine sand into the shield tunnel in a pressure blowing and filling mode: the method comprises the steps of excavating earthwork at a position of a pipe piece to be removed, and designing N paths of concrete temporary supports from top to bottom, wherein the N-1 th path of concrete temporary supports are positioned above a tunnel, the N-1 th path of concrete temporary supports are positioned on the pipe piece of the tunnel and below the center line of the pipe piece, and on the basis of completing the N-1 th path of concrete temporary supports, hole guiding is carried out on the N-1 th path of concrete temporary supports, sand blowing grouting is carried out in the pipe piece to be removed in a station, wherein N is a positive integer not less than 4;
fourth, excavating earthwork below the center line of the shield segment: the earthwork is excavated to the position 0.5m below the center line of the shield segment, the number of layers of earth stratified excavation, the number of sections of each layer, the retaining width and the retaining height of retaining wall soil and the time limit of the segmented excavation are determined according to the space-time effect foundation pit excavation, the segmented and layered balanced excavation is carried out, basin-type excavation is adopted in the foundation pit excavation, and the earthwork excavation is prevented from over-excavation and long-pull groove construction;
step five, removing the top shield segment: digging out the part of the shield segment above the position in the fourth step by using an excavator;
step six, erecting temporary supports: carrying out temporary support on the Nth concrete at the horizontal position of the excavated shield;
step seven, excavating the rest part of the segment and constructing a shield ring beam: removing the rest part of the duct piece by using an excavator, constructing a shield ring beam from top to bottom, and plugging a gap part between the duct piece and the enclosure structure;
step eight, continuously excavating to the bottom of the foundation pit: and continuing excavating to the bottom of the foundation pit by using an excavator and a manual excavating mode.
The lake-phase deposition weak stratum subway tunnel-first-station-later segment dismantling method is characterized by comprising the following steps of: in the first step, the section steel range is set to be 23 m-24 m outside the main body ground continuous wall of the line station with the range of about the large mileage, and each annular pipe piece in the section steel range is provided with a truss frame so as to ensure the safety of the pipe pieces outside the station during foundation pit excavation.
The lake-phase deposition weak stratum subway tunnel-first-station-later segment dismantling method is characterized by comprising the following steps of: in the second step, a sand-blowing grouting plugging wall is arranged at intervals of 3 spans, reinforcing steel bars with phi 16@150 are arranged in a bidirectional manner in a circular ring with the shield center as an origin and the diameter of 2000mm, radial arrangement is adopted for reinforcing steel bars outside the circular ring, reinforcing steel bars with phi 16 are arranged in a double-layer radial manner in an angle deflection of 5 degrees, and are connected with reinforcing steel bar planting of shield segments, and the depth of the planted reinforcing steel bars is 200mm.
The lake-phase deposition weak stratum subway tunnel-first-station-later segment dismantling method is characterized by comprising the following steps of: thirdly, after the N-1 concrete temporary support reaches 85% of the design strength, firstly filling fine sand into a shield tunnel without excavating a foundation pit, and adopting a pressure blowing and grouting mode during filling, firstly carrying out middle grouting in each section of area, and finally controlling grouting pressure well for grouting at two ends, and when the filling reaches 1/3 of the shield height, carrying out primary grouting, wherein the grouting pressure is controlled to be 0.2MPa by adopting cement slurry with the mass ratio of 1:1; after the reinforcement body reaches the design strength, continuing to perform blowing filling, and performing primary grouting when the filling reaches 2/3 of the shield height, wherein the grouting pressure is controlled to be 0.3MPa by adopting cement slurry with the mass ratio of 1:1; blowing, filling and filling are carried out again after the reinforcement body reaches the design strength, the whole cavity range is filled, grouting is carried out, and the grouting pressure is controlled to be 0.3-0.5 MPa; and a hot rolled seamless steel pipe is selected as the grouting pipe, the grouting pipe is inserted into the bottom filled by the current sand blowing before each grouting, the volume of single grouting slurry is not more than 0.3 times of the volume filled by the current sand blowing, and P32.5 slag silicate cement is adopted as cement.
The lake-phase deposition weak stratum subway tunnel-first-station-later segment dismantling method is characterized by comprising the following steps of: in the fourth step, the foundation water level of the section must be ensured to be 100cm below the earth excavation surface before each excavation, each layer of earth is excavated to the elevation of the supporting surface, and then the foundation water level is manually grooved.
Compared with the prior art, the invention has the following advantages:
1. according to the invention, as the section steel supporting and reinforcing measures are added to the section steel permanently used outside the station during foundation pit excavation, the section steel is not damaged during foundation pit excavation in the construction of the tunnel-before-station method; because the measures of grouting the blocking wall by blowing sand are arranged every 3 spans of the duct piece to be removed, the grouting is tight, the internal stress is uniform, the risk of removing the duct piece is reduced, the support is erected in time after the duct piece is partially removed, the monitoring is enhanced, the ground connection wall after the duct piece is removed is stabilized, the risk of removing the duct piece is reduced, and the popularization and the use are facilitated.
2. According to the invention, the shield segments to be dismantled are subjected to sand-blasting grouting treatment, so that the segments can still form a complete annular stress system after being partly dismantled, the intensity of soil pressure in a passive area of a foundation pit is ensured, the problem that the underground diaphragm wall can generate excessive horizontal displacement in the process is solved, the method is reliable and stable, the using effect is good, the use effect is good, the permanent shield segments outside a station are well protected, and the permanent shield segments are not damaged in the process of excavation of the foundation pit.
3. The method has the advantages that the steps are simple, the reinforcing bars of the grouting blocking wall are arranged in a partitioned mode, the reinforcing bars are arranged in a double-layer bidirectional mode, the external reinforcing bars are connected with the reinforcing bars of the shield segments, the compactness of grouting of the grouting is guaranteed, the operation is simple, the shield segments are quickly removed, a proper construction field is provided for the follow-up foundation pit excavation work, the excavator can be flexibly used in the foundation pit, and the popularization and the use are convenient.
In summary, the invention provides the method for grouting the guide holes of the demolished duct piece on the basis of reinforcing the passive area of the foundation pit by adopting the triaxial mixing piles, and the grouting blocking wall is arranged on a specific span to ensure the packing compactness, so that the duct piece can still form a complete annular stress system after the demolished part, the shield duct piece outside the station is additionally provided with the shield inner-type steel support to ensure the safety of the duct piece, the problem that the ground connecting wall can generate excessive horizontal displacement in the demolishing process of the shield duct piece is solved, the safe use of the duct piece in the tunnel is ensured, the method is efficient, the operation is simple, and a proper construction site is provided in the follow-up construction, so that the engineering can be smoothly carried out, and the popularization and the use are convenient.
The technical scheme of the invention is further described in detail through the drawings and the embodiments.
Drawings
Fig. 1 is a layout diagram of the section of jurisdiction inner section steel of the outer shield of the station of the present invention.
FIG. 2 is a schematic view of a grouting blocking wall according to the present invention.
FIG. 3 is a schematic diagram of the construction of the sand-blasting grouting of the present invention.
Fig. 4 is a schematic view of the shield segment removal of the present invention.
Fig. 5 is a schematic view of temporary support for erection of the present invention.
Fig. 6 is a flow chart of the method of the present invention.
Reference numerals illustrate:
1-section steel; 2-corner section steel; 3-segment;
5-shield tunneling; 6-internal steel bars; 7-external steel bars;
8-N-1 th temporary concrete support; 9-grouting pipe;
11-Nth concrete temporary support.
Detailed Description
As shown in fig. 1 to 6, the method for removing segments of a tunnel-first station and a tunnel-last station of a subway in a weak stratum deposited by a lake phase comprises the following steps:
step one, adding a shield inner section steel reinforcing structure to a shield segment outside a station: reinforcing all shield segments 3 in the ring 20 from the station by using the section steel 1 in a shape of a well, so as to ensure the safety of the shield segments 3;
the section steel 1 is spliced in a 'well' shape, and the angle section steel 2 is used in the splicing junction to tightly reinforce all shield segments 3 in the ring 20 of the station, and the contact part of the section steel and the shield segments is protected by the annular section steel, so that the safety of the shield segments in excavation of a foundation pit is ensured.
Step two, performing sand-blasting grouting on the pipe piece to be removed to form a plugging wall: setting a sand-blowing grouting plugging wall at intervals of 3 spans;
filling fine sand into the shield tunnel in a pressure blowing and filling mode: the method comprises the steps of excavating earthwork at the position of a duct piece 3 to be dismantled, designing N concrete temporary supports from top to bottom, wherein an N-1 concrete temporary support 8 is positioned above a tunnel, an N concrete temporary support 11 is positioned on the tunnel duct piece 3 and below the central line of the duct piece 3, and on the basis of completing the N-1 concrete temporary support 8, conducting hole guiding on the surface of the N-1 concrete temporary support 8, and conducting sand blowing grouting in the duct piece to be dismantled in a station, wherein N is a positive integer not less than 4;
fourth, excavating earthwork below the center line of the shield segment: the earthwork is excavated to the position 0.5m below the center line of the shield segment, the number of layers of earth stratified excavation, the number of sections of each layer, the retaining width and the retaining height of retaining wall soil and the time limit of the segmented excavation are determined according to the space-time effect foundation pit excavation, the segmented and layered balanced excavation is carried out, basin-type excavation is adopted in the foundation pit excavation, and the earthwork excavation is prevented from over-excavation and long-pull groove construction;
step five, removing the top shield segment: digging out the part of the shield segment above the position in the fourth step by using an excavator;
when the shield segment is excavated, the grouting layer outside the shield segment is removed by using an excavator and a wind cannon, the attention is proper, the shield segment is not damaged as much as possible, 2-3 rings of segments are crushed at the position which is away from the left and right of the gate decade ring during construction, the subsequent construction operation surface is created, the segment is dismantled according to the symmetrical principle, and the foundation pit monitoring is enhanced during the dismantling process.
Step six, erecting temporary supports: making an N-th concrete temporary support 11 at the horizontal position of the excavated shield;
the end well and the 5-10 shaft range are supported by concrete and are supported on the waist beam; the concrete support and the waist beam concrete have the strength of C35, besides the end well and the 5-10 shaft range, the steel support adopts ∅ (t=16mm) steel supports with the average spacing of 2.75m, the steel supports are supported on the waist beam, and the anti-falling measures are arranged by applying the anti-falling shaft force to the steel supports.
Step seven, excavating the rest part of the segment and constructing a shield ring beam: removing the rest part of the duct piece by using an excavator, constructing a shield ring beam from top to bottom, and plugging a gap part between the duct piece and the enclosure structure;
step eight, continuously excavating to the bottom of the foundation pit: and continuing excavating to the bottom of the foundation pit by using an excavator and a manual excavating mode.
The excavator continues to excavate in the country, and adopts manual excavation to the earthwork 30cm above the elevation of the designed pit bottom, the local super-excavated pit is filled with gravel and sand to the designed elevation, and after the excavation is carried out to the pit bottom, the foundation pit groove inspection, the construction grounding grid, the laying substrate cushion layer, the construction bottom plate and the side wall waterproof layer are carried out.
In the first embodiment, in the step one, the range of the section steel is set to be 23 m-24 m outside the main body ground continuous wall of the station with the range of the mileage, and each ring pipe piece in the range of the section steel is provided with a truss frame so as to ensure the safety of the pipe pieces outside the station during foundation pit excavation.
In the embodiment, in the second step, a grouting blocking wall is arranged every 3 spans, inner reinforcing steel bars 6 with phi 16@150 are arranged in a circular ring with the diameter of 2000mm in a bidirectional manner by taking the center of a shield as an origin, outer reinforcing steel bars 7 outside the circular ring are arranged in a radial manner, outer reinforcing steel bars 7 with phi 16 are arranged in a double-layer radial manner in an angle deflection of 5 degrees, the grouting blocking wall is connected with a shield segment planting bar, and the planting bar depth is 200mm.
In the embodiment, in the third step, after the N-1 th concrete temporary support 8 reaches 85% of the design strength, foundation pit excavation is not performed, fine sand is filled into the shield tunnel 5, a pressure blowing and filling mode is adopted during filling, middle grouting is performed in each section of area, grouting pressure is well controlled for grouting at two ends, grouting is performed once when the filling reaches 1/3 of the shield height, cement slurry with the mass ratio of 1:1 is adopted for grouting pressure controlled to be 0.2MPa; after the reinforcement body reaches the design strength, continuing to perform blowing filling, and performing primary grouting when the filling reaches 2/3 of the shield height, wherein the grouting pressure is controlled to be 0.3MPa by adopting cement slurry with the mass ratio of 1:1; blowing, filling and filling are carried out again after the reinforcement body reaches the design strength, the whole cavity range is filled, grouting is carried out, and the grouting pressure is controlled to be 0.3-0.5 MPa; for the grouting pipe 9, hot rolled seamless steel pipes are selected, the grouting pipe 9 is inserted into the bottom filled by the current sand blowing before each grouting, the volume of single grouting slurry is not more than 0.3 times of the volume filled by the current sand blowing, and P32.5 slag silicate cement is adopted as cement.
In the fourth embodiment, in the step, the foundation excavation process is required to follow the principle of 'supporting along with excavation and covering concrete under the foundation', the ground water level of the section must be ensured to be 100cm below the earth excavation surface before each excavation, each layer of earth is excavated to the elevation of the supporting surface, and then the artificial slotting is performed.
When the method is used, as the section steel supporting and reinforcing measures are added to the section steel which is permanently used outside the station when the foundation pit is excavated, the damage to the section steel is avoided when the foundation pit is excavated in the construction of the tunneling-before-station method; because the measures of grouting the blocking wall by blowing sand are arranged every 3 spans of the duct piece to be removed, the grouting is tight, the internal stress is uniform, the risk of duct piece removal is reduced, the support is erected in time after the duct piece is partially removed, the monitoring is enhanced, the ground connection wall after the duct piece is removed is stabilized, and the risk of duct piece removal is reduced as well; the shield segment to be dismantled is subjected to sand-blasting grouting treatment, so that the segment can still form a complete annular stress system after being partly dismantled, the intensity of soil pressure in a passive area of a foundation pit is ensured, the problem that the underground diaphragm wall can generate excessive horizontal displacement in the process is solved, the method is reliable and stable, the use effect is good, the use effect of the permanent shield segment outside a station is good, the permanent shield segment is well protected, and the permanent shield segment is not damaged in the process of excavation of the foundation pit; the grouting blocking wall steel bars are arranged in a partitioned mode, the steel bars are arranged in a double-layer bidirectional mode, the outer steel bars 7 are connected with shield segments in a reinforcing mode, the compactness of grouting of the grouting is guaranteed, the operation is simple, the shield segments are rapidly removed, a proper construction site is provided for the follow-up foundation pit excavation work, and the excavator can be flexibly used in the foundation pit.
The foregoing description is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and any simple modification, variation and equivalent structural changes made to the above embodiment according to the technical substance of the present invention still fall within the scope of the technical solution of the present invention.
Claims (5)
1. A lake facies deposition weak stratum subway tunnel-first and station-last segment dismantling method is characterized by comprising the following steps:
step one, adding a shield inner section steel reinforcing structure to a shield segment outside a station: reinforcing all shield segments in the ring 20 from the station by using the section steel in a 'well' -shape, so as to ensure the safety of the shield segments;
step two, performing sand-blasting grouting on the pipe piece to be removed to form a plugging wall: setting a sand-blowing grouting plugging wall at intervals of 3 spans;
filling fine sand into the shield tunnel in a pressure blowing and filling mode: the method comprises the steps of excavating earthwork at a position of a pipe piece to be removed, and designing N paths of concrete temporary supports from top to bottom, wherein the N-1 th path of concrete temporary supports are positioned above a tunnel, the N-1 th path of concrete temporary supports are positioned on the pipe piece of the tunnel and below the center line of the pipe piece, and on the basis of completing the N-1 th path of concrete temporary supports, hole guiding is carried out on the N-1 th path of concrete temporary supports, sand blowing grouting is carried out in the pipe piece to be removed in a station, wherein N is a positive integer not less than 4;
fourth, excavating earthwork below the center line of the shield segment: the earthwork is excavated to the position 0.5m below the center line of the shield segment, the number of layers of earth stratified excavation, the number of sections of each layer, the retaining width and the retaining height of retaining wall soil and the time limit of the segmented excavation are determined according to the space-time effect foundation pit excavation, the segmented and layered balanced excavation is carried out, basin-type excavation is adopted in the foundation pit excavation, and the earthwork excavation is prevented from over-excavation and long-pull groove construction;
step five, removing the top shield segment: digging out the part of the shield segment above the position in the fourth step by using an excavator;
step six, erecting temporary supports: carrying out temporary support on the Nth concrete at the horizontal position of the excavated shield;
step seven, excavating the rest part of the segment and constructing a shield ring beam: removing the rest part of the duct piece by using an excavator, constructing a shield ring beam from top to bottom, and plugging a gap part between the duct piece and the enclosure structure;
step eight, continuously excavating to the bottom of the foundation pit: and continuing excavating to the bottom of the foundation pit by using an excavator and a manual excavating mode.
2. The lake facies deposition weak stratum subway tunnel-first-station segment dismantling method as claimed in claim 1, wherein the method is characterized by comprising the following steps of: in the first step, the section steel range is set to be 23 m-24 m outside the main body ground continuous wall of the line station with the range of about the large mileage, and each annular pipe piece in the section steel range is provided with a truss frame so as to ensure the safety of the pipe pieces outside the station during foundation pit excavation.
3. The lake facies deposition weak stratum subway tunnel-first-station segment dismantling method as claimed in claim 1, wherein the method is characterized by comprising the following steps of: in the second step, a sand-blasting grouting plugging wall is arranged at intervals of 3 spans, and the structure of the sand-blasting grouting plugging wall is as follows: the reinforcing steel bars with the diameter of 2000mm are arranged in two directions in a circular ring with the center of the shield as an origin, radial arrangement is adopted for the reinforcing steel bars with the diameter of 2000mm, radial arrangement is adopted for the reinforcing steel bars with the angle deflection of 5 degrees on the outer part of the circular ring, the reinforcing steel bars with the diameter of 16 degrees are arranged in a double-layer radial manner, the reinforcing steel bars are connected with reinforcing steel bar planting of shield segments, and the reinforcing steel bar planting depth is 200mm.
4. The lake facies deposition weak stratum subway tunnel-first-station segment dismantling method as claimed in claim 1, wherein the method is characterized by comprising the following steps of: thirdly, after the N-1 concrete temporary support reaches 85% of the design strength, firstly filling fine sand into a shield tunnel without excavating a foundation pit, and adopting a pressure blowing and grouting mode during filling, firstly carrying out middle grouting in each section of area, and finally controlling grouting pressure well for grouting at two ends, and when the filling reaches 1/3 of the shield height, carrying out primary grouting, wherein the grouting pressure is controlled to be 0.2MPa by adopting cement slurry with the mass ratio of 1:1; after the reinforcement body reaches the design strength, continuing to perform blowing filling, and performing primary grouting when the filling reaches 2/3 of the shield height, wherein the grouting pressure is controlled to be 0.3MPa by adopting cement slurry with the mass ratio of 1:1; blowing, filling and filling are carried out again after the reinforcement body reaches the design strength, the whole cavity range is filled, grouting is carried out, and the grouting pressure is controlled to be 0.3-0.5 MPa; and a hot rolled seamless steel pipe is selected as the grouting pipe, the grouting pipe is inserted into the bottom filled by the current sand blowing before each grouting, the volume of single grouting slurry is not more than 0.3 times of the volume filled by the current sand blowing, and P32.5 slag silicate cement is adopted as cement.
5. The lake facies deposition weak stratum subway tunnel-first-station segment dismantling method as claimed in claim 1, wherein the method is characterized by comprising the following steps of: in the fourth step, the foundation water level of the section must be ensured to be 100cm below the earth excavation surface before each excavation, each layer of earth is excavated to the elevation of the supporting surface, and then the foundation water level is manually grooved.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111113196.1A CN113669084B (en) | 2021-09-23 | 2021-09-23 | Lake facies deposition weak stratum subway tunnel-first and station-last segment dismantling method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111113196.1A CN113669084B (en) | 2021-09-23 | 2021-09-23 | Lake facies deposition weak stratum subway tunnel-first and station-last segment dismantling method |
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| JP2008095400A (en) * | 2006-10-12 | 2008-04-24 | Zenitaka Corp | Diagonal cable removal method |
| CN103742155B (en) * | 2013-12-24 | 2017-01-04 | 中国神华能源股份有限公司 | A kind of long-span segment method for dismounting |
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| CN110821503B (en) * | 2019-11-27 | 2021-10-15 | 中铁九局集团第四工程有限公司 | Construction method for main body of ultra-deep shield section air shaft after tunnel advance |
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