CN218622244U - In-situ protection structure for underground cable penetrating through excavation of subway foundation pit - Google Patents

Abstract

Relate to subway building engineering field, provide an underground cable's normal position protection architecture is passed in excavation of subway foundation ditch, the cable spanes on subway foundation ditch, includes: the subway foundation pit support structure comprises a foundation pit support structure arranged on two sides of a subway foundation pit, wherein a gap with the width of A is formed at a cable of the foundation pit support structure; the reinforced concrete baffles are arranged in the gap and are stacked up and down, and two ends of each reinforced concrete baffle are connected with foundation pit support structures on two sides of the gap; the reinforcing structures are arranged on the two sides of the notch and on the outer side of the foundation pit maintenance structure; and the in-situ protection structure is erected on the foundation pit maintenance structure and the reinforcing structure and supports the cable. The method is used for solving the technical problems of slow construction progress, unstable power supply network and investment waste of the urban underground cable channel. The method has the advantages of shortening the construction period of the project, reducing cutting connection to a power supply network, reducing the risk of operating faults of a power line, reducing the project investment and having a flexible scheme.

Description

In-situ protection structure for underground cable penetrating through excavation of subway foundation pit

Technical Field

The utility model relates to a subway building engineering field, more specifically relates to a subway foundation pit excavates and passes in situ protection architecture of underground cable.

Background

In the process of city construction, if high-voltage cables above 30KV are encountered, a method of engineering avoidance or pipeline moving and modifying is generally adopted. However, in subway engineering, the station position of the subway line is controlled by various factors, and the scale of the open excavation foundation pit of the subway is large, so that once the station position of the subway is determined, the adjustment is very difficult. Therefore, in the subway engineering, a migration scheme is generally adopted for various pipelines which conflict with the subway engineering.

There are a great deal of problems in city underground cable changes that move, influence the pipeline and change progress and subway main part construction progress. The main problems are 1) slow moving and reforming construction progress, which affects the construction progress of main projects and causes idling and laboring; 2) Cutting and connecting a power supply network, increasing the risk of operating faults of a power line, causing potential safety hazards of power supply, and being inconsistent with the increasingly improved national requirement on the power supply reliability of the power grid; 3) The investment is extravagant, and underground cable is moved to outside the construction range at first temporarily during the subway engineering construction, moves back to the original route after the subway engineering construction is accomplished, leads to circuitous route and overlapping investment, increases subway engineering construction cost.

Under the influence of the factors, the in-situ protection measures are taken for the urban underground cable channel, and the method has the advantages of accelerating the construction progress, improving the stability of a power supply network, saving investment and the like.

SUMMERY OF THE UTILITY MODEL

The utility model discloses aim at overcoming above-mentioned prior art's at least one defect (not enough), provide a subway foundation pit excavates the normal position protection architecture that passes underground cable for the construction progress of solving city underground cable passageway is slow, and the power supply network is unstable and invests extravagant technical problem.

The utility model provides a technical scheme be, a subway foundation pit excavates the normal position protection architecture that passes underground cable, the cable spanes on subway foundation pit, include: the subway foundation pit support structure comprises a foundation pit support structure arranged on two sides of a subway foundation pit, wherein a gap with the width of A is formed at a cable of the foundation pit support structure; the reinforced concrete baffles are arranged in the gap and are stacked up and down, and two ends of each reinforced concrete baffle are connected with foundation pit support structures on two sides of the gap; the reinforcing structures are arranged on the two sides of the notch and on the outer side of the foundation pit maintenance structure; and the in-situ protection structure is erected on the foundation pit maintenance structure and the reinforcing structure and supports the cable. The method is favorable for reducing the vibration of the soil layer, reinforcing the excavated soil layer and protecting the cable from being supported under the reinforced concrete baffles which are overlapped layer by layer to form an in-situ protection structure with enough supporting force.

3-10 reinforced concrete baffles, wherein the height H of each reinforced concrete baffle is 1.5-1.8 m. The stability of the excavated space of the soil layer is improved, and the construction operation of workers below the cable is facilitated.

The in-situ protection structure comprises: the bearing main beam is erected on the foundation pit support structure and the reinforcing structure; and the two ends of the bearing secondary beams are supported on the bearing main beam, and the middle part of the bearing secondary beams supports the cable. The bearing protection of the cable is facilitated, and the load of the foundation pit support structure is reduced.

At least one bearing secondary beam is distributed above the plurality of reinforced concrete baffles. Is favorable for balancing the stress of the reinforced concrete baffle.

The reinforced structure is rectangle oblique pile column structure, two rectangle oblique pile column structures of breach both sides from top to bottom incline to breach center from breach both sides respectively to fuse, wholly be the trapezium structure of falling in the cable below. The foundation pit supporting structure is favorable for forming a protective layer with a supporting effect for the foundation pit, and the inclined piles are favorable for saving building materials.

The inclination angle of the rectangular inclined pile column structure is 60-85 degrees, and the width of the upper bottom of the inverted trapezoidal structure is as follows: the width of the lower bottom is 2: 1-1.5. The construction material is saved as much as possible on the specific acting force for protecting the foundation pit.

Still including set up in between two rectangle batter post column structures, the reinforced support structure of the below of cable, the last base support cable of reinforced support structure, two rectangle batter post column structures of both sides limit laminating. The supporting force of the cable in-situ protection is further enhanced.

The width A of the notch is between 2.5 and 4m, and the thickness of each reinforced concrete baffle is between 500 and 800 mm. The special supporting force can be provided for the in-situ protection structure load at the notch.

The plurality of load-bearing secondary beams are distributed at equal intervals below the cable, and the interval width is 0.8-1.2 m. The method is favorable for evenly distributing the specific cable load on the bearing secondary beam at a specific position, and the stability of the in-situ protection structure is improved.

The cross-sectional area of the rectangular inclined pile column structure is between (4 m multiplied by 6 m) - (6 m multiplied by 10 m). The cable support device is beneficial to providing support force for cables of specific loads, and occupies the floor area as little as possible.

Compared with the prior art, the beneficial effects of the utility model are that: the construction period of the project is shortened, cutting and connection to a power supply network are reduced, the risk of operation faults of a power line is reduced, the project investment is reduced, and the scheme is flexible.

Drawings

Fig. 1 is a plan view of the in-situ protection method of the present invention.

Fig. 2 is the utility model discloses a section schematic diagram is consolidated in the foundation ditch outside.

Fig. 3 is the utility model discloses a building envelope "breach" department concrete baffle construction sketch map.

Fig. 4 is the in-situ cross-sectional view of the underground cable in the foundation pit of the present invention.

Figure 5 is the utility model discloses an underground cable successive layer excavation soil layer section sketch map in the foundation ditch.

Figure 6 is the utility model discloses a foundation ditch earthwork subregion excavation schematic diagram.

Fig. 7 is a cross-sectional view of the bailey frame protection of the present invention.

Fig. 8 is a detail view of the protective cross section of the bailey frame of the present invention.

The attached drawings indicate the following: the cable 100, the subway foundation pit 200, the foundation pit bottom 210, the foundation pit upper base 211, the foundation pit lower base 212, reinforced concrete baffle 240, bear the main girder 300, bear the secondary beam 400, breach 510, reinforced structure 600, rectangle oblique pile column structure 700, rectangle oblique pile column upper base 710, rectangle oblique pile column lower base 720, the reinforced bearing structure 800.

Detailed Description

The drawings of the present invention are for illustration purposes only and are not to be construed as limiting the invention. For a better understanding of the following embodiments, certain features of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product; it will be understood by those skilled in the art that certain well-known elements of the drawings and descriptions thereof may be omitted.

Examples

As shown in fig. 1, the utility model discloses a method for protecting underground cable in situ when crossing subway foundation pit mainly relates to the in situ protection in two positions, firstly, the crossing department of underground cable 100 and foundation pit retaining structure influences the width a within range, when retaining structure does not do under the in situ protection condition, adopt soil layer reinforcement measure to carry out the slant and consolidate the foundation pit security problem outside the foundation pit; and secondly, when the underground cable crosses the foundation pit, the bearing main beam 300 and the bearing secondary beam 400 are adopted to carry out in-situ protection on the underground cable.

As shown in fig. 2, a main bearing beam 300 and a secondary bearing beam 400 are used for protecting both sides of the underground cable 100 in the foundation pit in situ, and together form an in situ protection system. The underground cable 100 needs to be firmly connected with the secondary bearing beam 400, and the secondary bearing beam 400 needs to be firmly connected with the main bearing beam 300; the connection mode can adopt bolts, welding, steel wire binding and the like. In order to avoid the in-situ protection system in the foundation pit 200 from being disturbed and damaged by the construction in the foundation pit, boxes such as wood boards, steel plates and the like can be arranged around the in-situ protection system. The main bearing beam 300 can be independently provided with stressed members such as a Bailey truss, section steel, a reinforced concrete beam, a steel pipe and the like according to specific conditions, and can also use an inner support of a foundation pit as the stressed member; the secondary load beam 400 may be reinforced concrete beam, section steel, steel pipe, steel bar, etc. according to specific conditions. When the width B of the foundation pit is large and the size of the member of the load-bearing main beam 300 is large, a temporary fulcrum can be additionally arranged in the foundation pit 200 to reduce the span of the load-bearing main beam 300.

When the underground cable 100 is buried deep, the cross section of the sub-carrier 400 may be formed as a U-shaped member to be suspended below the main carrier 300 in order to avoid other problems caused by lowering the elevation of the main carrier 300. Particularly, when the section and the weight of the underground cable 100 are small, the bearing secondary beam 400 can be omitted, and the underground cable 100 is directly fixed on the bearing main beam 300 in the single-side foundation pit.

As shown in fig. 3, when the reinforcement structure 600 is constructed outside the foundation pit, the reinforcement on the ground avoids the enclosure structure gap range a, the soil outside the enclosure structure gap range a is reinforced within the range of the transverse reinforcement width C, and the region 41 below the underground cable 1 is reinforced. According to the geological condition, the reinforcing mode can adopt the processes of grouting, jet grouting piles, MJS piles and the like which can be obliquely reinforced; the indexes to be achieved by the reinforcing body need to be determined based on the hydrogeology condition, the width A of the gap of the enclosure structure, the excavation depth of the foundation pit and the like, and the foundation pit safety is emphasized. In particular, if the geological conditions outside the excavation are very good, such as in the case of moderately weathered, slightly weathered rock formations, the reinforcement structure 600 outside the excavation may be eliminated.

As shown in fig. 4, the main bearing beam 300 is erected above the bearing beam at the gap 510 of the foundation pit enclosure structure at the enclosure structure, and the bearing beam at the gap 510 of the foundation pit enclosure structure and the foundation pit enclosure structures at the two sides are connected with the embedded steel bars and the connectors in the foundation pit enclosure structure, the embedded steel bars are thrown, the steel bars are planted at the later stage, the anchor bolts are additionally arranged at the later stage, and the like. Particularly, the distance between the two bearing main beams 300 can be increased, the bearing main beams 300 are directly erected above the top crown beam of the foundation pit enclosure structure, and the bearing beams at the gap of the foundation pit enclosure structure can be eliminated in the connection mode, but the bearing secondary beam 400 is correspondingly lengthened.

As shown in fig. 5 and 6, in the process of vertically excavating the foundation pit downwards, the foundation pit should be excavated in layers and in blocks, that is, when each layer is excavated, the soil body a1 near the gap range a of the enclosure structure is excavated first, and the reinforced concrete baffle 240 at the gap 510 of the foundation pit enclosure structure is constructed in time, and when the reinforced concrete baffle 240 at the gap 510 of the foundation pit enclosure structure reaches the soil layer a2 with the design strength outside the gap, the process is repeated until the foundation pit is excavated to the bottom 210 of the foundation pit. The vertical layered excavation depth is closely related to the geological condition, the gap width A of the enclosure structure, the development condition of underground water and the like; the vertical layered excavation depth can be increased when the geological condition is better, the gap width A of the enclosure structure is smaller and underground water is not developed. When each layer is excavated, the soil body a1 near the gap range A of the enclosure structure is firstly excavated, so that the influence on the range of a foundation pit when the gap of the enclosure structure generates water inrush can be reduced, and the emergency treatment work is facilitated. The reinforced concrete baffle 240 at the gap 510 of the foundation pit support structure can adopt the forms of cast-in-place reinforced concrete slabs, steel plates, prefabricated slabs and the like, but the fixed connection between the reinforced concrete baffle 240 at the gap 510 of the foundation pit support structure and the sealing and waterproof work are required to be done. The reinforced concrete baffle 240 at the gap 510 of the foundation pit support structure is vertically partitioned into blocks h1, h2, h3, h4, h5 and the like according to the excavation condition, the geological condition and the like of the foundation pit 200, the vertical height of each block is determined, and the vertical partition height is not excessively large. Particularly, when the self-stability of the stratum is good and the water content of the stratum is small, the reinforced concrete baffle 240 at the gap of the foundation pit support structure can be eliminated.

As shown in fig. 1 to fig. 4, the embodiment of the present invention provides an in-situ protection method for underground cable crossing subway foundation pit, which comprises the following steps:

the first step is as follows: a subterranean cable 100 is probed.

Before construction, the actual routing and the burial depth of the underground cable 100 are determined by using various modes such as a detection tool, field excavation and the like, and the underground cable 100 is determined to be arranged in a cable trough box, wherein the cross-sectional dimension of the cable trough box is 1000mm x 600mm (width x height). And reasonably determining the gap width A =3m of the foundation pit support structure according to the geological condition, the protection requirement of the underground cable, the construction level and the like.

The second step is that: and constructing a foundation pit enclosure structure.

And constructing the foundation pit enclosure structure in the region outside the range of the gap width A of the foundation pit enclosure structure according to the sequence of leveling field → constructing guide wall → grooving of the continuous wall → hoisting reinforcement cage → pouring the underwater concrete of the continuous wall → constructing the first reinforced concrete support at the bottom of the crown beam, so as to form the foundation pit enclosure structure in the region outside the range of the gap width A of the foundation pit enclosure structure. In the construction process of the foundation pit support structure, safety protection of the underground cable 100 needs to be well done.

The third step: and (5) reinforcing the structure 600 outside the foundation pit.

An oblique jet grouting pile is adopted, a foundation pit outer side soil body reinforcing structure 600 is constructed outside a gap width A of a foundation pit support structure, a transverse reinforcing width C and a transverse reinforcing thickness D are reasonably determined according to geological conditions and the like, in the embodiment, C =8m and D =5m. The diagonal reinforcement body is required to cover all areas of the lower portion of the protected underground cable 100, and the vertical depth is the same as that of the continuous wall. The main requirements of the jet grouting pile are as follows:

1) The water-cement ratio of cement slurry of the jet grouting pile is 0.8-1.0. The cement is ordinary Portland cement with strength grade not lower than 42.5.

2) The unconfined compressive strength of the jet grouting pile 28d is not less than 0.8Mpa, the anti-permeability coefficient is not less than 10-5cm/s, and re-spraying is carried out when the jet grouting pile is unqualified.

The number of pile quality inspection points is not less than 2% of the number of construction holes and not less than 6 points;

the fourth step: the main load-bearing beam 300 and the sub-load-bearing beam 400 are erected.

And digging out all soil bodies on two sides of the underground cable 1 to be protected, erecting a bearing main beam 300, and according to load calculation, adopting a double-row single-layer (DS) Bailey frame as the bearing main beam 300, wherein two ends of the Bailey frame are erected on a 600mm-800mm bearing beam arranged at a notch of the continuous wall. Transverse trenches with the longitudinal distance of about 1m are dug below the protected underground cable trough box, the bearing secondary beam 400 is transversely arranged below the underground cable, and two ends of the bearing secondary beam 100 are erected on the bailey frames.

The fifth step: and excavating the soil body in the foundation pit to the base in a layered and partitioned manner.

And after the enclosure structure and the in-situ protection of the cable in the foundation pit are completed, excavating the soil body in the foundation pit in a layered and partitioned manner. In order to reduce the risk of water and mud outburst at the gap of the continuous wall, the thickness of the layered excavation is not more than 1.8m. When each layer of earthwork is excavated, the earthwork needs to be excavated in different areas; firstly, excavating earthwork a1 of 5m & ltx & gt 2m (length & ltx & gt) near a continuous wall gap, constructing a reinforced concrete baffle 240 with the thickness of 600mm, and connecting reinforcing steel bars of the reinforced concrete baffle with a reinforcing steel bar connector reserved in the existing continuous wall; and after the reinforced concrete baffle 240 reaches the design strength, excavating the rest earthwork a2. And circulating the steps until the excavation of the foundation pit 200 is completed.

And a sixth step: and (5) dismantling the in-situ protection system.

And (6) excavating the foundation pit 200 to the base 210, constructing a subway main body structure from bottom to top, and completing earth covering and backfilling above a top plate. The earth backfill below the underground cable needs to ensure compactness, and measures such as grouting and the like can be added if necessary. And when the foundation below the underground cable can bear the load of the underground cable, dismantling the underpinned main beam in the foundation pit and the underpinned secondary beam in the foundation pit, thereby completing the in-situ protection of the underground cable.

The protection measure in the embodiment when the pipeline is not conflicted. The standards for judging the safety state of the pipeline in engineering adopt two types, namely a stress judgment method, namely judging whether the stress of the worst position of the pipeline reaches the strength limit of the pipeline; and the second is a strain judgment method, namely, whether the deformation value of the most unfavorable position of the pipeline reaches the deformation limit of the pipeline is judged. Pipeline protection measures are also based on these two pipeline safety criteria.

In the embodiment, the cable channel penetrates through the whole connecting channel foundation pit, the cable pipeline cannot be moved during construction, and corresponding protective measures are taken during underground channel construction.

In the embodiment, the cable channel is not used as a building envelope, and the stratum outside the pit is reinforced and a concrete slab is molded.

When the cable channel is not used as an enclosure structure, on the basis of adopting the reinforcement of the stratum outside the pit, in the process of excavating the foundation pit, the gap of the enclosure structure is sealed by adopting the molded concrete, so that the enclosure structure forms a closed system. The applicable condition is no sand layer, and the geological condition is better.

The cable channel in the foundation pit of the embodiment is a measure for keeping the cable channel in place.

In order to realize the in-situ protection of the cable channel, the in-situ protection problem of the cable channel at the position of the enclosure structure is treated, and the suspension protection problem of the cable channel in the foundation pit is also treated. Namely, before the foundation pit is excavated, the cable channel is fixed on the transverse stress member, so that the cable channel can still keep the original shape after the soil body is excavated.

Generally, the cable channel is laid in a cable well trench, a cable duct bank, a cable trough box, a trenchless horizontal directional drill and the like. Due to different laying modes, the influence on the in-situ protection measure of the cable channel in the foundation pit is mainly the dead weight of the cable channel.

Cable channel normal position safeguard measure in the foundation ditch can not be different because of subway main part foundation ditch and affiliated foundation ditch, all need satisfy in the foundation ditch that cable channel still can keep the original state after the earthwork excavates. Generally, an inner support (reinforced concrete support or steel support) is arranged in a foundation pit and used for resisting the water and soil pressure outside the foundation pit, and under the condition, a transverse stress component of the cable channel can 'borrow' the inner support; of course, when the inner support is not used, an independent transverse stress member such as a Bailey frame, section steel and the like can be additionally arranged.

Through the above analysis, the in-situ protection measures are mainly related to the following two aspects: the dead weight of the cable channel and the transverse stress component are independently arranged.

And (5) in-situ protection scheme of the bailey truss in the foundation pit.

In order to improve the lateral stability of the beret beam, at least two beret beams are generally adopted to form an in-situ protection system, which is shown in the attached fig. 7 to 8 in detail.

It is obvious that the above embodiments of the present invention are only examples for clearly illustrating the technical solutions of the present invention, and are not limitations to the specific embodiments of the present invention. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims (10)

1. An in-situ protection structure for subway foundation pit excavation through underground cables, the cables crossing over the subway foundation pit, comprising:

the subway foundation pit support structure comprises a foundation pit support structure arranged on two sides of a subway foundation pit, wherein a gap with the width of A is formed at a cable of the foundation pit support structure; the reinforced concrete baffles are arranged in the gaps in an up-down stacked mode, and two ends of each reinforced concrete baffle are connected with foundation pit support structures on two sides of the gap;

the reinforcing structures are arranged on the two sides of the notch and on the outer side of the foundation pit support structure;

and the in-situ protection structure is erected on the foundation pit support structure and the reinforcing structure and supports the cable.

2. The in-situ protection structure for underground cables during excavation of the subway foundation pit according to claim 1, wherein the in-situ protection structure comprises 3-10 reinforced concrete baffles, and the height H of each reinforced concrete baffle is 1.5-1.8 m.

3. The in-situ protection structure for excavation of a subway foundation pit through underground cables as claimed in claim 1,

the in-situ protection structure comprises:

the bearing main beam is erected on the foundation pit support structure and the reinforcing structure;

and the two ends of the bearing secondary beams are supported on the bearing main beam, and the middle part of the bearing secondary beams supports the cable.

4. The in-situ protection structure for underground cable crossing in excavation of subway foundation pit according to claim 3, wherein at least one load-bearing secondary beam is distributed above said plurality of reinforced concrete baffles.

5. The in-situ protection structure for underground cables during excavation of subway foundation pit according to claim 1, wherein the reinforcing structure is a rectangular inclined pile column structure, and two rectangular inclined pile column structures on two sides of the gap are inclined from top to bottom towards the center of the gap respectively, and are merged below the cables to form an inverted trapezoid structure as a whole.

6. The in-situ protection structure for underground cable crossing in excavation of subway foundation pit according to claim 5, wherein the inclination angle of said rectangular inclined pile column structure is between 60 ° and 85 °, and the width of the upper bottom of the inverted trapezoid structure is: the width of the lower bottom is 2: 1-1.5.

7. The in-situ protection structure for underground cables during excavation of the subway foundation pit according to claim 5, further comprising a reinforcing support structure arranged between the two rectangular inclined pile column structures and below the cables, wherein the cable is supported by the upper bottom edge of the reinforcing support structure, and the two rectangular inclined pile column structures are attached to the two side edges of the reinforcing support structure.

8. An in-situ protection structure for underground cables during excavation of a subway foundation pit according to any one of claims 1 to 7, wherein the width A of the gap is between 2.5 and 4m, and the thickness of each reinforced concrete baffle plate is between 500 and 800 mm.

9. An in-situ protection structure for underground cables during excavation of a subway foundation pit according to any one of claims 3 to 4, wherein the plurality of load-bearing sub-beams are distributed at equal intervals below the cables, and the interval width is 0.8-1.2 m.

10. An in-situ protection structure for underground cable through excavation of a subway foundation pit as claimed in any one of claims 5 to 7, wherein the cross-sectional area of the rectangular inclined pile column structure is between (4 m x 6 m) - (6 m x 10 m).

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