CN116517026A - Method for building underground station under settlement-sensitive facility - Google Patents

Method for building underground station under settlement-sensitive facility Download PDF

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Publication number
CN116517026A
CN116517026A CN202310775565.6A CN202310775565A CN116517026A CN 116517026 A CN116517026 A CN 116517026A CN 202310775565 A CN202310775565 A CN 202310775565A CN 116517026 A CN116517026 A CN 116517026A
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China
Prior art keywords
pipe curtain
underground
steel
settlement
sensitive
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CN202310775565.6A
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Chinese (zh)
Inventor
聂子云
谭小兵
朱占国
张继清
张春雷
王正松
张晨明
董秀竹
胡奇凡
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China Railway Design Corp
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China Railway Design Corp
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Priority to CN202310775565.6A priority Critical patent/CN116517026A/en
Publication of CN116517026A publication Critical patent/CN116517026A/en
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    • EFIXED CONSTRUCTIONS
    • E02HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02DFOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D29/00Independent underground or underwater structures; Retaining walls
    • E02D29/04Making large underground spaces, e.g. for underground plants, e.g. stations of underground railways; Construction or layout thereof
    • EFIXED CONSTRUCTIONS
    • E02HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02DFOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D17/00Excavations; Bordering of excavations; Making embankments
    • E02D17/02Foundation pits
    • EFIXED CONSTRUCTIONS
    • E02HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02DFOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D19/00Keeping dry foundation sites or other areas in the ground
    • E02D19/06Restraining of underground water
    • E02D19/10Restraining of underground water by lowering level of ground water
    • EFIXED CONSTRUCTIONS
    • E02HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02DFOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D29/00Independent underground or underwater structures; Retaining walls
    • E02D29/16Arrangement or construction of joints in foundation structures
    • EFIXED CONSTRUCTIONS
    • E02HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02DFOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D3/00Improving or preserving soil or rock, e.g. preserving permafrost soil
    • E02D3/12Consolidating by placing solidifying or pore-filling substances in the soil
    • EFIXED CONSTRUCTIONS
    • E02HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02DFOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D31/00Protective arrangements for foundations or foundation structures; Ground foundation measures for protecting the soil or the subsoil water, e.g. preventing or counteracting oil pollution
    • E02D31/02Protective arrangements for foundations or foundation structures; Ground foundation measures for protecting the soil or the subsoil water, e.g. preventing or counteracting oil pollution against ground humidity or ground water

Abstract

The invention belongs to the technical field of underground structure underground excavation construction, and discloses a method for constructing an underground station under facilities sensitive to settlement. Constructing foundation pits on two sides of facilities sensitive to sedimentation, and excavating the foundation pits to the top plate position; penetrating facilities sensitive to sedimentation along the outer contour of a top plate and part of a side wall of an underground station in a foundation pit, and arranging a top longitudinal pipe curtain and a side longitudinal pipe curtain; continuously excavating foundation pits at two sides to a certain position below the pipe curtain, and horizontally and advanced reinforcing soil bodies with a height range set below the pipe curtain in the foundation pits; soil with a height range is set below a pipe curtain by longitudinal segmentation excavation, side enclosure and middle steel columns are constructed in an excavated space below the pipe curtain, steel cross beams are erected on the steel columns, and pre-stressing force is applied to the steel columns through jacks arranged on the steel columns until the soil with the height range is set below the pipe curtain is completely longitudinally penetrated; and synchronously and vertically excavating foundation pits below the pipe curtain and on two sides, erecting a horizontal steel support in time, applying a pre-axial force, and sequentially constructing the station structure layer by layer after excavating to the bottom.

Description

Method for building underground station under settlement-sensitive facility
Technical Field
The invention belongs to the technical field of underground structure underground excavation construction, and particularly relates to a method for constructing an underground station under facilities sensitive to settlement.
Background
With the improvement of the economic level of China, urban construction is greatly developed, the rail transit is more and more restricted factors, and the underground excavation construction method becomes the choice for constructing subway stations under the conditions of incapacity of interrupting traffic, complex ground environment and the like. At present, the traditional underground excavation construction method is mainly used for constructing a large-span underground structure and comprises a middle hole method, a side hole method, a column hole method and a hole pile method, wherein the middle hole method, the side hole method, the column hole method and the hole pile method are mainly used for constructing a large-span underground structure, the large sections (the construction range of a top plate of the hole pile method) to be excavated are mainly divided into a plurality of small sections, grouting advance support is carried out on small guide pipes, the small sections are excavated step by strictly controlling the footage of each excavation, and finally the large sections (the construction range of the top plate of the hole pile method) are formed.
In order to solve the defects of the traditional underground excavation method and improve the applicability of the large-span underground excavation method, the related engineering technicians in China also make some new attempts and improvements on the large-span underground excavation method. CN108868778B discloses a trenchless construction method for large-scale underground structures, which is a significant improvement for constructing large-span underground structures by adopting high-rigidity advanced support and high-rigidity vertical support, and the method is characterized in that a longitudinal pipe curtain is arranged along the outline of an underground top plate and a part of side wall; constructing a longitudinal pilot tunnel under the pipe curtain, and constructing guard piles and crown beams in the longitudinal pilot tunnel; and excavating a transverse pilot tunnel at a position corresponding to the middle upright post in the longitudinal pilot tunnel, constructing the middle upright post and a pile foundation in the transverse pilot tunnel, constructing a top cross beam of an underground structure in the transverse pilot tunnel, forming a combined supporting system of a longitudinal pipe curtain, a transverse reinforced concrete beam and a vertical temporary upright post, and then excavating and constructing the underground structure. The method can be applied to underground excavation engineering of a facility sensitive to sedimentation, but has certain limitation, firstly, the supporting structure of the method needs to be applied to a longitudinal pilot tunnel and a transverse pilot tunnel, the working surface is relatively more, the construction space of the pilot tunnel is relatively smaller, the construction organization is relatively complex in open excavation, and the construction period is relatively longer in open excavation; the roof is provided with a plurality of transverse construction joints, the requirement on the waterproof construction quality is high, and certain waterproof hidden danger exists on the roof when the construction joints are improperly treated; in order to control the ground surface subsidence, the station roof beam and the roof plate are closely attached to the pipe curtain, the requirements on the fluidity and the compactness of the roof plate concrete are higher, and once a larger gap exists above the roof plate, the influence on the ground surface subsidence is larger; the beam and the upright post structure of the top plate structure are used as permanent structures, after the upper soil load is passively converted to the beam and the upright post, the sedimentation size is determined by the gap between the beam and the pipe curtain and the deformation bearing capacity of the upright post foundation, and once the earth surface sedimentation occurs, the earth surface sedimentation can not be adjusted any more; the method has higher requirements on construction quality of construction units, and when a large-span underground structure such as a subway station or the like passes through facilities sensitive to sedimentation such as railways, subways, airports, expressways, cultural relics and the like, the method needs to be cautious in view of the current domestic construction environment.
In order to solve the defects and shortcomings of the existing large underground structure underground excavation construction method, particularly the problem that the underground excavation construction cannot be performed under facilities sensitive to sedimentation or under the geological condition of a weak soil layer, a novel underground excavation construction method of a large-span underground structure is necessary to be provided.
Through the above analysis, the problems and defects existing in the prior art are as follows: (1) The prior art has high requirements on geological conditions and has poor practicability in saturated soft soil stratum. (2) The prior art has large risk in the construction process and high labor intensity. (3) the engineering cost of the prior art is high. (4) the prior art has low construction efficiency and long construction period; the underground excavation section and the open excavation section cannot be constructed synchronously, the construction space is limited, large excavation operation cannot be carried out, and the underground excavation construction period is increased. (5) the prior art is poor in waterproof quality. (6) The prior art can not effectively control the surface subsidence and the horizontal deformation of the surrounding environment.
Disclosure of Invention
In order to overcome the problems in the related art, the disclosed embodiments of the present invention provide a method for constructing an underground station under a facility sensitive to settlement, which can effectively control the underground station underground excavation method of surface settlement.
The technical scheme is as follows: the method for constructing the underground station under the facilities sensitive to sedimentation comprises the following steps:
s1, constructing foundation pits on two sides of facilities sensitive to sedimentation, and excavating the foundation pits to the top plate positions of underground stations;
s2, penetrating facilities sensitive to sedimentation under the outer contours of a top plate and a part of side walls of the underground excavation section in the foundation pit, and arranging top and side longitudinal pipe curtains;
s3, continuously excavating foundation pits at two sides to a certain position below the pipe curtain, and horizontally and advanced reinforcing soil mass with a height range set below the pipe curtain in the foundation pits;
s4, longitudinally excavating a first section of soil body with a height range, constructing side enclosures, middle steel columns and pile foundations in an excavated space below the pipe curtain, arranging steel columns on the side enclosures at positions corresponding to the middle steel columns, erecting steel cross beams on the steel columns, tightly propping the steel cross beams against the pipe curtain by applying pre-stressing force through jacks arranged on the steel columns, tightly plugging gaps between the steel cross beams and the pipe curtain by adopting fine stone concrete or steel gaskets, and constructing a first section of crown beam closely attached to the side pipe curtain;
s5, repeating the step S4, continuously excavating a soil layer below the pipe curtain in a longitudinal section by a height range, and constructing side enclosures, steel upright posts, steel cross beams and crown beams until all the height range is longitudinally penetrated;
s6, synchronously and vertically excavating foundation pits below the pipe curtain and on two sides, erecting a horizontal steel support, and applying a pre-stress in time by using a jack on the steel support;
s7, sequentially working station structures layer by layer after excavation, constructing the top surface of a top plate in the stage of excavation to the lower part of a steel beam, and performing plain concrete backfilling on a gap between the top plate and a pipe curtain;
s8, unloading the jack, removing all the steel upright posts, plugging structural holes at the steel upright posts, and backfilling foundation pits at two sides.
In step S1, the sedimentation-sensitive facility comprises: railway, urban rail, airport, expressway, urban arterial road, major pipeline, old and old cultural relic building and other overground or underground facilities with strict requirements on settlement deformation control.
In step S1, in constructing foundation pits on both sides of the settlement-sensitive facility, when one side of the settlement-sensitive facility is limited by ground conditions, foundation pits are provided on one side of the settlement-sensitive facility.
In the step S2, before the construction of the longitudinal pipe curtain, grouting reinforcement is carried out on the stratum in the area where the pipe curtain enters and exits the hole.
In step S3, the horizontal advanced reinforcement is performed by advanced deep hole grouting reinforcement, horizontal spin-jet reinforcement, or horizontal freeze reinforcement.
In step S4, the side enclosure is a bored pile or an underground diaphragm wall constructed under the clean condition of the bottom space treatment.
In the step S4, after a horizontal temporary supporting measure is set between the side pipe curtain and the steel upright post on the enclosure, the crown beam is constructed after the soil body with the height range set below the pipe curtain is completely penetrated in the step S5.
In the step S4 and the step S6, the jacks on the steel upright posts and the steel supports adopt an axial force automatic compensation system, and the construction process timely and properly adjusts the pre-added axial force of each jack through a hydraulic pump station and a control station according to the earth surface settlement condition so as to control the earth surface settlement and the enclosure horizontal displacement.
In the step S4 and the step S8, the loading and unloading of the jack of the steel upright post are carried out in a grading manner, and the loading and unloading are timely adjusted according to the ground surface subsidence and horizontal displacement real-time monitoring result.
In the steps S1 to S8, when the groundwater level is high and precipitation cannot be performed, a water stop filler is arranged in a gap between locking openings of the pipe curtains, and high-pressure rotary spraying water is arranged between the side guard piles.
Another object of the present invention is to provide a use of the method for constructing an underground station under a settlement-sensitive facility in constructing an underground station in a weak soil formation.
It is another object of the present invention to provide a method for constructing an underground station under a settlement-sensitive facility, and a construction method for constructing a large-span tunnel in a weak soil stratum and a use of the method for constructing a large-span underground engineering.
By combining all the technical schemes, the invention has the advantages and positive effects that: the method for building the underground station under the facilities sensitive to settlement provided by the invention adopts the following scheme: constructing foundation pits on two sides of facilities sensitive to sedimentation, and excavating the foundation pits to the top plate position; penetrating facilities sensitive to sedimentation along the outer contour of a top plate and part of a side wall of an underground station in a foundation pit, and arranging a top longitudinal pipe curtain and a side longitudinal pipe curtain; continuously excavating foundation pits at two sides to a certain position below the pipe curtain, and horizontally and advanced reinforcing soil bodies with a height range set below the pipe curtain in the foundation pits; soil with a height range is set below a pipe curtain by longitudinal segmentation excavation, side enclosure and middle steel columns are constructed in an excavated space below the pipe curtain, steel cross beams are erected on the steel columns, and pre-stressing force is applied to the steel columns through jacks arranged on the steel columns until the soil with the height range is set below the pipe curtain is completely longitudinally penetrated; synchronously excavating foundation pits vertically below the pipe curtain and at two ends, erecting a horizontal steel support in time and applying a pre-axial force; and after the excavation is finished, sequentially working the station structure layer by layer, backfilling gaps between the top plate and the pipe curtain, and removing all the steel upright posts and the horizontal steel supports.
The invention has strong applicability: the traditional underground excavation construction method is used for fully exerting self-bearing capacity of soil, the requirement on the earth covering depth is generally not less than 6m, the top plate is generally made into an arch structure, the single-hole excavation span is generally not more than 8m, the number of layers of a station is generally not more than 2, the requirement on geological conditions is high, and the method has a small number of applications in cities with few stratum well; the technical scheme is also applicable as long as the geological conditions suitable for the open excavation method are met, and the technical scheme is assisted with a certain degree of stratum reinforcing water stopping measure, so that the method can be applied to saturated soft soil stratum.
The construction risk of the invention is low: the traditional underground excavation and excavation process needs to fully utilize the space-time effect of the soil body and the bearing capacity of the soil body, a great amount of manpower is exposed under the face in the excavation and support process, once the conditions of too aggressive construction, untimely support, large disturbance to stratum, geological mutation or upper pipe line rupture and water seepage and the like occur, the construction risk is extremely high, collapse accidents frequently occur, casualties and property loss are caused, and bad social influence is caused; the construction of the underground excavation supporting system is basically implemented by large machinery, the construction process is basically risk-free, the labor intensity is low, the large excavation operation can be performed after the supporting system is constructed, and the excavation process is basically risk-free due to the large supporting rigidity.
The invention has low construction cost: the traditional underground excavation station generally needs to be provided with a large number of auxiliary measures such as advanced grouting, closed tunnel face and the like, temporary middle partition walls and middle partition plates, and is abandoned in a large amount afterwards, so that the engineering cost is high; the technical scheme has the advantages that the supporting distance is large, the steel cross beams, the steel upright posts and the steel supports can be recycled, besides the pipe curtain and the steel upright post pile foundation are additionally increased compared with an open excavation foundation pit supporting system, the economic cost of other supporting systems is equivalent to that of the open excavation method, and the engineering cost is low.
The invention has high construction efficiency: the traditional underground excavation construction method generally needs to carry out underground excavation section construction after the working surfaces at two ends are excavated to the bottom and the structure is completed, and the working surfaces are excavated in a dividing way, each working surface needs to be staggered for a certain distance, each working surface is mutually influenced, the work efficiency is low, and the construction period is long; after the pipe curtain and the vertical supporting system are completed, the underground excavation section and the open excavation section can be constructed synchronously, the construction space is large, the large excavation operation can be carried out, and the underground excavation construction period is shortened greatly.
The waterproof quality of the invention is good: the traditional underground excavation construction method has the advantages that a large number of construction joints are arranged in the circumferential direction and the longitudinal direction due to the procedures of the secondary lining construction by the subsection excavation and the subsection construction, meanwhile, the overlapping parts of the waterproof layer are large, and the hidden trouble of water seepage of the structure in the using stage is large; the technical scheme adopts the structure similar to the open cut station to construct along the way, has fewer structural construction joints, fewer waterproof overlapping joints, large construction space and guaranteed construction quality, and has good waterproof quality.
The invention has small earth surface subsidence: the traditional underground excavation construction method has the advantages that as the underground excavation construction method is used for carrying out repeated disturbance on the stratum and repeated stress conversion, and the ground surface subsides into passive subsidence due to the clearance reasons behind the primary support and the secondary lining, the subsidence is difficult to control, and once the subsidence happens, the subsidence is difficult to recover the position which is generally applied to the stratum and has better condition and strict surrounding environment influence requirement; according to the technical scheme, the axial force compensation system is applied to the steel upright post, when settlement is early-warned, the axial force of the steel upright post jack is timely adjusted through the axial force compensation system, active jacking is carried out, so that the ground surface settlement is effectively controlled, and the horizontal deformation of the surrounding environment can be effectively controlled through the horizontal steel support pre-axial force.
The method for building the underground station under the facilities sensitive to settlement provided by the invention comprises the following steps: constructing shallow foundation pits on two sides of facilities sensitive to sedimentation; a longitudinal pipe curtain is arranged in the shallow foundation pit along the lower part of the outer contour of the top plate and part of the side wall of the underground station in a penetrating way; horizontal reinforcement is carried out on the soil layer in the height range of about 4m below the pipe screen in the shallow foundation pit; excavating soil with a height range of about 4m in a horizontal and longitudinal section-by-section manner below the pipe curtain, after each section of excavation is completed, timely arranging side enclosures and middle temporary steel columns (containing pile foundations) in an excavated space below the pipe curtain, applying a crown beam on the enclosures, erecting steel cross beams on the steel columns and the crown beam, and applying a pre-stress to the steel columns through jacks arranged on the steel columns and the crown beam until the height space of about 4m below the pipe curtain is completely and horizontally penetrated; synchronously excavating foundation pits below the pipe curtain and at two ends, erecting a horizontal steel support in time and applying a pre-axial force; the open excavation section and the underground excavation section are synchronously and layer by layer sequentially used for building a station structure after the excavation is completed, the horizontal steel support is removed, and plain concrete backfilling is carried out on the gap between the top plate and the pipe curtain; and removing all the steel upright posts, plugging structural holes at the upright posts, and covering soil and backfilling foundation pits at two sides.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the disclosure and together with the description, serve to explain the principles of the disclosure;
FIG. 1 is a flow chart of a method for building an underground station under a settlement-sensitive facility provided by an embodiment of the present invention;
FIG. 2 is a schematic cross-sectional view provided by an embodiment of the present invention;
FIG. 3 is a schematic longitudinal section of sequence Shi Gongbu 1 provided by an embodiment of the invention;
fig. 4 is a schematic longitudinal section view of a construction step 2 according to an embodiment of the present invention;
FIG. 5 is a schematic longitudinal section of sequence Shi Gongbu 3 provided by an embodiment of the invention;
FIG. 6 is a schematic longitudinal section of sequence Shi Gongbu provided by an embodiment of the invention;
FIG. 7 is a schematic longitudinal section of a construction step 5 according to an embodiment of the present invention;
FIG. 8 is a schematic longitudinal section of a construction step 6 according to an embodiment of the present invention;
FIG. 9 is a schematic longitudinal section of a working procedure 7 provided in an embodiment of the present invention;
FIG. 10 is a schematic longitudinal section of sequence Shi Gongbu provided by an embodiment of the invention;
in the figure: 1. a pipe curtain; 2. enclosing; 3. a steel upright; 4. a steel cross beam; 5. a jack; 6. a crown beam; 7. a foundation pit; 8. a steel support; 9. a top plate; 10. facilities sensitive to sedimentation; 11. pile foundation; 12. horizontal advanced reinforcement; 13. and (5) backfilling plain concrete.
Detailed Description
In order that the above objects, features and advantages of the invention will be readily understood, a more particular description of the invention will be rendered by reference to the appended drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. The invention may be embodied in many other forms than described herein and similarly modified by those skilled in the art without departing from the spirit or scope of the invention, which is therefore not limited to the specific embodiments disclosed below.
The present invention will be described in detail with reference to the accompanying drawings by taking an example of constructing a coordinate quasi-span double-deck underground station under a rail transit line, and when the following description refers to the accompanying drawings, the same numerals in different drawings denote the same or similar elements unless otherwise indicated. The implementations described in the following exemplary examples are not representative of all implementations consistent with the present disclosure. Rather, they are merely examples of apparatus and methods consistent with some aspects of the present disclosure as detailed in the accompanying claims.
The method comprises the following steps: constructing foundation pits 7 on two sides of a facility 10 sensitive to sedimentation, and excavating the foundation pits 7 to the position of a top plate 9; a top and side longitudinal pipe curtain 1 is arranged in the foundation pit 7 along the lower part of the top plate 9 of the underground station and the outer contour of a part of the side wall by penetrating through facilities 10 sensitive to sedimentation; the foundation pit 7 at two sides is continuously excavated to a certain position below the pipe curtain 1, and the soil body with a height range set below the pipe curtain 1 is horizontally and advanced reinforced 12 in the foundation pit 7; soil with a height range is set below a pipe curtain 1 by longitudinal segmentation excavation, a side enclosure 2 and a middle steel upright post 3 are constructed in an excavated space below the pipe curtain 1, a steel cross beam 4 is erected on the steel upright post 3, and a pre-stressing force is applied to the steel upright post 3 through a jack 5 arranged on the steel upright post 3 until the soil with the height range is set below the pipe curtain 1 and is completely longitudinally penetrated;
the foundation pit 7 below the pipe curtain 1 and on two sides synchronously excavates vertically, and a horizontal steel support 8 is erected in time and a pre-axial force is applied; and excavating to bottom, and sequentially constructing the station structures layer by layer. And backfilling gaps between the top plate 9 and the pipe curtain 1, and dismantling all the steel upright posts 3 and the horizontal steel supports 8. The invention has the advantages of strong applicability, low construction risk, low construction cost, high construction efficiency, good waterproof quality and small ground surface subsidence.
Embodiments as shown in fig. 1, an embodiment of the present invention provides a method for building an underground station by underground excavation under a settlement-sensitive facility, including the steps of:
s1, constructing foundation pits 7 on two sides of a facility 10 sensitive to sedimentation, and excavating the foundation pits 7 to a top plate 9 position, as shown in FIG. 3;
s2, penetrating a facility 10 sensitive to sedimentation in the shallow foundation pit 7 along the top plate 9 and the outer contour of part of the side wall, and arranging a top and side longitudinal pipe curtain 1, as shown in figure 4;
s3, continuously excavating foundation pits 7 at two sides to a position 4m below the pipe curtain 1, and horizontally and advanced reinforcing 12 is carried out on soil mass with a height range of about 4m below the pipe curtain 1 in the foundation pits 7, as shown in FIG. 5;
s4, longitudinally excavating a soil body at the first section of a high range of about 4m below the pipe curtain 1;
constructing a lateral enclosure 2 and a middle steel upright post 3 (comprising pile foundation 11) in an excavated space below the pipe curtain 1, arranging the steel upright post 3 on the enclosure 2 at a position corresponding to the middle steel upright post 3, erecting a first steel cross beam 4 on the steel upright post 3 in time, applying a pre-stressing force to the steel upright post 3 through a jack 5 arranged on the steel upright post 3 to tightly prop up the steel cross beam 4 and the pipe curtain 1, tightly plugging a gap between the steel cross beam 4 and the pipe curtain 1 by adopting fine stone concrete or a steel gasket, constructing a first section of crown beam 6, and tightly attaching the crown beam 6 and the lateral pipe curtain 1, as shown in fig. 6;
s5, repeating the step S4 to excavate the high soil layer about 4m below the pipe curtain 1 in a segmented mode until all the high soil layers are horizontally penetrated, as shown in FIG 7;
s6, synchronously excavating foundation pits 7 below and on two sides of the pipe curtain 1, erecting a horizontal steel support 8 in time, and applying pre-axial force in time by using a jack 5 on the steel support 8, as shown in FIG. 8;
s7, excavating the bottom, sequentially working the station structure layer by layer, constructing the top surface of a top plate 9 of the underground excavation section below the steel cross beam 4, and performing plain concrete backfilling 13 on a gap between the top plate 9 and the pipe curtain 1, as shown in FIG 9;
s8, unloading the jack 5, removing all the steel upright posts 3, plugging structural holes at the steel upright posts 3, and backfilling foundation pits 7 (shown in figure 3) at two sides by earthing, as shown in figure 10.
In step S1, the settlement-sensitive facility 10 is generally an above-ground or underground facility requiring very strict deformation control, such as a railway, a urban rail, an airport, an expressway, an urban arterial road, a major pipeline, an old cultural relic building, or the like.
In a preferred embodiment, in step S1, foundation pits 7 are constructed on both sides of the settlement-sensitive apparatus 10, and shallow foundation pits 7 are provided on one side of the settlement-sensitive apparatus 10 when one side of the settlement-sensitive apparatus 10 is limited by ground conditions.
In step S2, before the construction of the longitudinal pipe curtain 1, grouting reinforcement is performed on the stratum in the area where the pipe curtain 1 enters and exits the hole.
In step S3, the horizontal advanced reinforcement 12 is performed by advanced deep hole grouting reinforcement, horizontal spin-jet reinforcement, or horizontal freeze reinforcement.
The side enclosure 2 in the step S4 is a bored pile or an underground diaphragm wall constructed under the clean condition of the bottom space treatment.
In a preferred embodiment, after a horizontal temporary supporting measure is set between the side pipe curtain 1 and the steel upright posts 3 on the enclosure 2 in the step S4, the crown beam 6 can be constructed after the 4m high soil below the pipe curtain 1 is completely penetrated in the step S5.
In a preferred embodiment, in the step S4 and the step S6, the jacks 5 on the steel upright posts 3 and the steel supports 8 can adopt an axial force automatic compensation system, and the construction process can timely and properly adjust the pre-axial force of each jack 5 through a hydraulic pump station and a control station according to the earth surface subsidence condition so as to control the earth surface subsidence and the horizontal displacement of the enclosure 2.
In a preferred embodiment, the loading and unloading of the jacks 5 of the steel upright 3 in step S4 and in step S8 are carried out in stages, and the loading and unloading are adjusted in time according to the real-time monitoring results of the ground subsidence and horizontal displacement.
In a preferred embodiment, in the step S1-S8, when the groundwater level is high and precipitation is impossible, a water stop filler is disposed in the gap between the pipe curtains 1 and a high-pressure rotary spraying water is disposed between the side enclosure 2 piles.
Fig. 3-10 are exemplary illustrations of the construction method of the present invention, and these examples are provided only for further illustration of the details of the method of the present invention and the effects thereof, and are not limiting of the present invention. In engineering implementation, the technical personnel can carry out corresponding derivatization according to the engineering external environment condition and combining engineering geology and hydrogeology conditions. In particular, the method of the present invention is not limited to use in the construction of underground stations, but may be used in the construction of railway underground stations, underground municipal roads, underground commercial streets, underground street passages or similar underground structures of other function. Such transformations are the general derivatives that one of ordinary skill in the art would accomplish without undue effort and are within the scope of the methods of the present invention.
In the foregoing embodiments, the descriptions of the embodiments are emphasized, and in part, not described or illustrated in any particular embodiment, reference is made to the related descriptions of other embodiments.
The construction method provided by the embodiment of the invention can be applied to the construction of underground stations, large-span tunnels and similar large-span underground projects under facilities 10 sensitive to settlement or in weak soil strata.
According to the invention, the large-rigidity support system and the pre-axial force system are applied to a large-span underground excavation structure, a novel underground excavation design concept based on the large-rigidity support system is created, a longitudinal pipe curtain 1 is adopted as an enclosure 2 for an upper soil body, a side pile or a ground connecting wall is adopted as the enclosure 2 for a side soil body, vertical settlement is controlled by arranging a steel upright post 3 of the pre-axial force servo system, horizontal displacement is controlled by arranging a steel support 8 capable of pre-axial force, and the characteristics of the large-rigidity support system of an open excavation foundation pit 7 are inherited, so that the large span, the safety, the high efficiency and the low cost of underground excavation engineering are realized. The underground excavation is not limited by geological conditions and surrounding environments, the safety risk is basically avoided, the application range of the underground excavation method is greatly widened, and the underground excavation method can be widely adopted under facilities 10 sensitive to settlement or in soft soil areas.
While the invention has been described with respect to what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

Claims (10)

1. A method of constructing an underground station under a settlement-sensitive facility, the method comprising the steps of:
s1, constructing foundation pits (7) on two sides of facilities (10) sensitive to sedimentation, and excavating the foundation pits (7) to the top plate (9) of an underground station;
s2, penetrating facilities (10) sensitive to sedimentation under the top plate (9) and part of the side wall outer contour of the underground excavation section in the foundation pit (7), and arranging top and side longitudinal pipe curtains (1);
s3, continuously excavating foundation pits (7) at two sides to a position below the pipe curtain (1), and horizontally and advanced reinforcing (12) is carried out on soil bodies with a height range set below the pipe curtain (1) in the foundation pits (7);
s4, a first soil body with a height range is set below a longitudinal excavation pipe curtain (1), a lateral enclosure (2), a middle steel upright post (3) and a pile foundation (11) are constructed in an excavated space below the pipe curtain (1), the steel upright post (3) is also arranged on the lateral enclosure (2) at a position corresponding to the middle steel upright post (3), a steel cross beam (4) is erected on the steel upright post (3), a pre-stressing force is applied through a jack (5) arranged on the steel upright post (3), the steel cross beam (4) is tightly propped against the pipe curtain (1), a gap between the steel cross beam (4) and the pipe curtain (1) is tightly plugged by fine stone concrete or a steel gasket, a first crown beam (6) is constructed, and the first crown beam (6) is tightly attached to the lateral pipe curtain (1);
s5, continuously excavating a soil layer with a height range under the pipe curtain (1) in a longitudinal section manner, and constructing a side enclosure (2), a steel upright post (3), a steel cross beam (4) and a crown beam (6) until all the height range is longitudinally penetrated;
s6, synchronously excavating foundation pits (7) at the lower part and the two sides of the pipe curtain (1) vertically, erecting a horizontal steel support (8), and applying a pre-stress in time by utilizing a jack (5) on the steel support (8);
s7, sequentially working a station structure layer by layer after the excavation is finished, constructing the top surface of a top plate (9) of the underground excavation section to the lower part of the steel cross beam (4), and performing plain concrete backfilling (13) on a gap between the top plate (9) and the pipe curtain (1);
s8, unloading the jack (5), removing all the steel upright posts (3), plugging structural holes at the steel upright posts (3), and covering soil and backfilling the foundation pits (7) at two sides.
2. Method of building an underground station under a settlement-sensitive installation according to claim 1, wherein in step S1 the settlement-sensitive installation (10) comprises: railway, urban rail, airport, expressway, urban arterial road, major pipeline, old and old cultural relic building and other overground or underground facilities with strict requirements on settlement deformation control.
3. Method for constructing an underground station under a settlement-sensitive installation according to claim 1, characterized in that in step S1, in constructing foundation pits (7) on both sides of the settlement-sensitive installation (10), foundation pits (7) are provided on one side of the settlement-sensitive installation (10) when one side of the settlement-sensitive installation (10) is limited by ground conditions.
4. Method for constructing an underground station under a settlement-sensitive installation according to claim 1, characterized in that, in step S2, the formation of the pipe curtain (1) in and out of the tunnel is grouting-reinforced before the construction of the longitudinal pipe curtain (1).
5. Method for constructing an underground station under a settlement-sensitive installation according to claim 1, characterized in that in step S3 the horizontal advanced reinforcement (12) is performed with advanced deep hole grouting reinforcement or horizontal spin-jet reinforcement or horizontal freeze reinforcement.
6. Method for constructing an underground station under a settlement-sensitive installation according to claim 1, characterized in that in step S4 the side containment (2) is a bored pile or a diaphragm wall constructed under clean conditions for the bottom space treatment.
7. The method for constructing an underground station under a settlement-sensitive facility according to claim 1, wherein in step S4, after a horizontal temporary support measure is provided between the side pipe curtain (1) and the steel column (3) on the enclosure (2), the crown beam (6) is constructed after the soil body below the pipe curtain (1) is completely penetrated in step S5.
8. The method for constructing an underground station under a settlement-sensitive facility according to claim 1, wherein in the step S4, the jacks (5) on the steel upright (3) and the steel support (8) adopt an automatic axial force compensation system, and the construction process is to properly adjust the pre-applied axial force of each jack (5) in time through a hydraulic pump station and a control station according to the earth surface settlement condition so as to control the earth surface settlement and the horizontal displacement of the enclosure (2).
9. Method for building underground stations under facilities sensitive to sedimentation according to claim 1, characterized in that in step S4 and in step S8 the loading and unloading of the jacks (5) of the steel uprights (3) are staged and the loading and unloading are adjusted in time according to the real-time monitoring results of the surface sedimentation and horizontal displacement.
10. The method for constructing underground stations under facilities sensitive to settlement according to claim 1, wherein in the steps S1 to S8, when the underground water level is high and precipitation is impossible, water stop filler is arranged in the gap between locking openings of the pipe curtains (1), and high-pressure rotary spraying water is arranged between piles of the side enclosures (2).
CN202310775565.6A 2023-06-28 2023-06-28 Method for building underground station under settlement-sensitive facility Pending CN116517026A (en)

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CN113847040A (en) * 2021-12-02 2021-12-28 中国铁路设计集团有限公司 Large-span non-column underground station underground excavation construction method
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