阅读说明：本技术 地铁车站基坑内大跨度超高压电力管沟悬吊装置及方法 (Large-span ultrahigh-voltage power pipe trench suspension device and method in subway station foundation pit ) 是由 王振坤 石艳军 艾晶晶 欧阳红星 曹富荣 简容海 郭二涛 于 2021-07-21 设计创作，主要内容包括：地铁车站基坑内大跨度超高压电力管沟悬吊装置及方法,包括电力管沟连接的钢结构桁架,钢结构桁架两端伸入电力管沟内,沿着钢结构桁架方向设置有多个格构支撑,格构支撑与钢结构桁架下端接触,格构支撑下端与基坑地面基础固定连接,电缆放置在电力管沟和钢结构桁架内,施工方法包括：电缆的防护、管沟的拆除、桁架的安装及基坑完成后的复原,可以较好地解决地铁车站施工中受电力管沟无法迁改影响车站施工,或者迁改周期长、费用高问题影响车站封顶工期的问题。(Large-span superhigh pressure power pipe ditch suspension device and method in subway station foundation ditch, including the steel construction truss that the power pipe ditch is connected, in steel construction truss both ends stretched into the power pipe ditch, be provided with a plurality of lattice supports along steel construction truss direction, lattice support and steel construction truss lower extreme contact, lattice support lower extreme and foundation ditch ground basis fixed connection, the cable is placed in power pipe ditch and steel construction truss, construction method includes: the protection of cable, the demolition of trench, the installation of truss and the recovery after the foundation ditch is accomplished can solve better in the subway station construction and can't move the problem that changes the influence station construction by the electric power trench, perhaps move and change the cycle length, the problem that the expense is high influences the time limit for a project of station capping.)

1. Large-span superhigh pressure power pipe ditch suspension device in subway station foundation ditch, a serial communication port, steel structure truss (2) of connecting including power pipe ditch (1), steel structure truss (2) both ends stretch into in power pipe ditch (1), be provided with a plurality of lattice support (3) along steel structure truss (2) direction, lattice support (3) and steel structure truss (2) lower extreme contact, lattice support (3) lower extreme and foundation ditch ground basis fixed connection, the cable is placed in power pipe ditch (1) and steel structure truss (2), the whole weight of cable and steel structure truss (2) is born jointly by a plurality of lattice support (3), steel structure truss (2) lower part and lattice support (3), the space that the foundation ditch formed is used for the construction.

2. The large-span ultrahigh-voltage power pipe trench suspension device in the subway station foundation pit as claimed in claim 1, wherein the steel structure truss (2) is formed by arranging four steel main beams (21) in parallel along a rectangle or a square, the steel main beams (21) are fixedly connected by steel cross beams (22), the steel cross beams (22) are fixedly connected end to end by oblique chord members (23), the two steel main beams (21) at the upper end are suspended and connected with a foundation pit supporting crown beam, and a steel truss cable support (24) for fixing cables is arranged in the steel structure truss (2).

3. The large-span ultrahigh-voltage power pipe trench suspension device in the subway station foundation pit as claimed in claim 2, wherein the steel main beams (21) and the steel cross beams (22) are all H-shaped steel beams.

4. The large-span ultrahigh-voltage power pipe trench suspension device in the subway station foundation pit as claimed in claim 3, wherein the lattice support (3) comprises two lattice columns (6) and two cast-in-place piles (4) which are fixedly connected up and down, the lower ends of the cast-in-place piles (4) are fixedly connected with the foundation pit ground, the two lattice columns (6) and the two cast-in-place piles (4) are respectively arranged on two sides of the steel structure truss (2), the two lattice columns (6) are fixedly connected through a supporting cross beam (7), the lower end of the steel structure truss (2) is arranged on the supporting cross beam (7), and the upper ends of the two cast-in-place piles (4) are fixedly connected through a bearing platform foundation (5).

5. The large-span ultrahigh-voltage power pipe trench suspension device in the subway station foundation pit as claimed in claim 4, wherein the lower end of the lattice column (6) is embedded into the cast-in-place pile (4) and poured together to form a whole, the lattice column (6) is formed by welding angle steel and steel plate lacing bars, and the lattice column (6) is inserted into the foundation.

6. The large-span ultrahigh-voltage power pipe trench suspension device in the subway station foundation pit as claimed in claim 5, wherein the steel structure truss (2) is formed by continuously connecting a plurality of sections of spliced steel main beams (21), the lattice supports (3) are supported at the spliced positions, and the foundation pit supporting structure of the power pipe trench (1) is supported by steel grating and sprayed concrete.

7. The suspension construction method for the large-span ultrahigh-voltage power pipe trench suspension device in the subway station foundation pit as claimed in claim 6, characterized in that the concrete steps of the construction are as follows:

step1, finding out the specific conditions of high voltage and cables in the power pipe trench (1) in the range of the station foundation pit, drawing a cable distribution diagram, marking the risk of cable moving, and marking the length and the range of the power pipe trench (1) to be suspended;

step2, installing an explosion-proof box at the joint position of the cable in the power pipe trench (1), filling the explosion-proof box with fireproof mud, and performing insulation treatment;

step3, installing an insulating bottom plate (10) at the bottom of the power pipe trench (1), and paving the insulating bottom plate (10), namely the bottom layer of the cable, with a fireproof sandbag (11);

step4, wrapping and protecting the cable by adopting an MPP power protection pipe (9), and plugging ports at two ends of the cable protection pipe by adopting fireproof mud;

step5, using a fireproof sand bag (11) to carry out layered protection on the cable, laying a layer of fireproof sand bag (11) on the MPP power protection pipe (9) of the topmost cable, and laying a fireproof plate (12) on the upper part;

step6, constructing a lattice column (6) and a foundation cast-in-place pile (4) of the lattice column (6) at the suspension supporting part of the power pipe trench (1);

step7, performing protective dismantling on the concrete structure of the power pipe trench (1) to be suspended;

step8, manufacturing and installing a steel structure truss (2) around the protected cable, wherein two sides of the steel structure truss (2) are connected with a foundation pit supporting crown beam in a suspension mode, the lower end of the steel structure truss (2) is supported by adopting lattice columns (6) and supporting cross beams (7), and a grounding device of the steel structure truss (2) is installed;

and Step9, laying the cables in the steel truss (2) on the steel truss cable bracket (24) in a layered mode according to voltage levels and fixing the cables by using a bandage.

8. The suspension construction method for the large-span ultrahigh-voltage power pipe trench in the foundation pit of the subway station as claimed in claim 7, wherein after the construction in the foundation pit is completed, the restoration steps of the power pipe trench (1) are as follows:

step10, after the foundation pit construction is completed and the top plate is backfilled to the bottom of the steel structure truss (2), bedding and laying of a bottom plate and a fireproof sand bag (11) are carried out on the bottoms of the power pipe trench (1) and the steel structure truss (2), the chord members (23) at the bottom of the truss are removed, and cables are layered and landed;

step11, removing the steel structure truss (2), cutting off the lattice supports (3) in sections, pouring the removed power pipe trench (1) again before restoration, and completing the restoration of the cable.

9. The large-span ultrahigh-voltage power pipe trench suspension construction method in the subway station foundation pit according to claim 7, characterized in that the Step7 comprises the following specific steps:

step7.1, cutting a cable support, connecting and grounding a power pipe trench cable support (13) in a power pipe trench (1) through a grounding flat iron (14), then cutting off the support, and taking fireproof, antistatic and ventilation measures when cutting off the support;

step7.2, cutting a top cover, drilling a hole in the top cover of the power pipe trench (1) to be detached and drilling through to form a top cover lifting hole (15), scribing a top cover cutting line (16) along the upper end of the side wall of the power pipe trench (1) to be detached, carrying out static cutting on the concrete structure of the power pipe trench (1) along the top cover cutting line (16), and lifting and transferring the cut top cover by using the top cover lifting hole (15) after the cutting is finished;

step7.2, cutting the side wall, marking a side wall cutting line (17) at the lower end of the side wall of the power pipe trench (1) to be dismantled, carrying out static cutting on the concrete structure along the side wall cutting line (17), and removing the cut side wall after cutting.

10. The large-span ultrahigh-voltage power pipe trench suspension construction method in the subway station foundation pit according to claim 7, characterized in that the power pipe trench (1) restored and removed in Step11 is cast according to the sequence of a bottom plate, a side wall and a top plate, the top plate of the pipe trench is made of small assembled customized steel templates, and the restoration work comprises civil construction of the pipe trench, grounding and cable support installation.

Technical Field

The invention relates to the technical field of urban rail transit and comprehensive pipe gallery construction, in particular to a large-span ultrahigh-voltage power pipe trench suspension device and method in a foundation pit of a subway station.

Background

In China, urban subway projects in various cities are generally radiated to suburbs from existing urban areas, most stations are located under urban arterial roads, various underground pipelines such as urban rainwater, sewage, natural gas, water supply, communication, electric power and the like are criss-cross, and various pipelines in a construction range are required to be permanently moved or temporarily moved and changed before subway station construction so as to meet the construction conditions of subway structures.

The domestic urban power supply network mainly comprises 330kV, 110kV, 10kV and other transformer substations, high-voltage and ultrahigh-voltage cables of 10kV, 110kV and the like are generally laid in power pipe ditches in cities, a large-area power supply task of a certain area of the city is undertaken, and the power cables undertake the important task of power conservation and supply and cannot be powered off randomly. Meanwhile, the electric power property department has strict control on electric power change, complex change procedures, long examination and approval period and high change cost. The reasonable construction period of civil engineering of a subway station is about 24 months, and the migration and modification periods of high-voltage and ultrahigh-voltage power pipelines and pipe ditches are generally more than 12 months according to the domestic existing subway construction experience, so that the subway construction with short construction period can not be met.

Disclosure of Invention

The invention aims to solve the technical problem of providing a large-span ultrahigh-voltage power pipe trench suspension device and method in a foundation pit of a subway station.

In order to solve the technical problems, the technical scheme adopted by the invention is as follows:

large-span superhigh pressure power pipe ditch hanging device in subway station foundation ditch, including the steel construction truss that the power pipe ditch is connected, steel construction truss both sides and excavation supporting hat roof beam suspend in midair and be connected, the steel construction truss both ends stretch into in the power pipe ditch, be provided with a plurality of lattice supports along steel construction truss direction, lattice support and the contact of steel construction truss lower extreme, lattice support lower extreme and foundation ditch ground basis fixed connection, the cable is placed in power pipe ditch and steel construction truss, the whole weight of cable and steel construction truss is born jointly by a plurality of lattice supports, steel construction truss lower part and lattice support, the space that the foundation ditch formed is used for the construction.

The steel structure truss is characterized in that the four steel main beams are arranged in parallel along a rectangle or a square, the steel main beams are fixedly connected through steel cross beams, the steel cross beams are fixedly connected through oblique chord members from head to tail, the two steel main beams at the upper end are suspended and connected with a foundation pit supporting crown beam, and a steel truss cable support used for fixing cables is arranged in the steel structure truss.

The steel main beam and the steel cross beam are both H-shaped steel beams.

Foretell lattice supports two lattice columns and two bored concrete piles of upper and lower fixed connection, bored concrete pile lower extreme and foundation ditch ground basis fixed connection, two lattice columns and two bored concrete piles are established respectively in steel construction truss both sides, by supporting beam fixed connection between two lattice columns, steel construction truss lower extreme is placed on supporting beam, two bored concrete pile upper ends are by cushion cap basis fixed connection.

The lower end of the lattice column is embedded into the cast-in-place pile and poured together to form a whole, the lattice column is formed by welding angle steel and steel plate batten strips, and the length of the inserted foundation of the lattice column is 3 m.

The steel girder of foretell steel construction truss for the multistage concatenation is formed by connecting in succession, and the span of single stride is 20 ~ 25m, and the lattice support supports in concatenation department, and electric power trench excavation supporting construction adopts steel grating + shotcrete to strut.

The suspension construction method using the large-span ultrahigh-voltage power pipe trench suspension device in the subway station foundation pit comprises the following specific steps:

step1, finding out the specific conditions of high voltage and cables in the power pipe trench in the range of the station foundation pit, drawing a cable distribution diagram, marking the risk of cable moving, and marking the length and the range of the power pipe trench to be suspended;

step2, installing an explosion-proof box at the joint position of the cable in the power pipe trench, filling the explosion-proof box with fireproof mud, and performing insulation treatment;

step3, installing an insulating bottom plate at the bottom of the power pipe trench, and paving the insulating bottom plate, namely the bottom layer of the cable, with a fireproof sandbag;

step4, wrapping and protecting the cable by adopting an MPP power protection pipe, and plugging ports at two ends of the cable protection pipe by adopting fireproof mud;

step5, performing layered protection on the cable by using a fireproof sand bag, flatly laying a layer of fireproof sand bag on the MPP power protection pipe of the topmost cable, and flatly laying a fireproof plate on the upper part of the MPP power protection pipe;

step6, constructing lattice columns and foundation cast-in-place piles of the lattice columns at the suspension supporting positions of the power pipe ditches;

step7, performing protective dismantling on the power pipe trench concrete structure needing to be suspended;

step8, manufacturing and installing a steel structure truss around the protected cable, wherein two sides of the steel structure truss are connected with a foundation pit supporting crown beam in a suspension mode, the lower end of the steel structure truss is supported by adopting lattice columns and supporting cross beams, and a grounding device of the steel structure truss is installed;

and Step9, laying the cables in the steel truss cable support layer by layer according to voltage grades and fixing the cables by using a binding belt.

After the construction in the foundation ditch is accomplished, the restoration step of power pipe ditch is:

step10, after the foundation pit construction is completed and the top plate is backfilled to the bottom of the steel structure truss, bedding layers are carried out on the bottoms of the power pipe trench and the steel structure truss, a bottom plate and a fireproof sand bag are laid, chord members at the bottom of the truss are removed, and cables are layered and landed;

and Step11, removing the steel structure truss, cutting off the lattice supports in sections, pouring the removed power pipe trench before restoration again, and finishing the restoration of the cable.

The specific steps of Step7 are as follows:

step7.1, cutting a cable support, connecting and grounding the cable support of the power pipe trench in the power pipe trench through a grounding flat iron, then cutting off the support, and taking fireproof, antistatic and ventilation measures when cutting off the support;

step7.2, cutting a top cover, drilling a hole on the top cover of the power pipe trench to be removed and drilling through the hole to form a top cover lifting hole, scribing a top cover cutting line along the upper end of the side wall of the power pipe trench to be removed, carrying out static cutting on the concrete structure of the power pipe trench along the top cover cutting line, and lifting and transferring the cut top cover by using the top cover lifting hole after the cutting is finished;

step7.2, cutting the side wall, marking a side wall cutting line at the lower end of the side wall of the power pipe trench to be dismantled, carrying out static cutting on the concrete structure along the side wall cutting line, and removing the cut side wall after cutting.

Pouring construction is carried out on the power pipe trench restored and detached in the Step11 according to the sequence of the bottom plate, the side wall and the top plate, the top plate of the pipe trench is made of small assembled customized steel templates, and restoration work comprises civil construction grounding of the pipe trench and installation of a cable support.

The large-span ultrahigh-voltage power pipe trench suspension device and method in the foundation pit of the subway station provided by the invention have the following beneficial effects:

1. the cable joint in the suspension protection construction range is provided with an explosion-proof box and plugging fireproof mud, so that the safety of moving the cable is ensured; the bottom of the pipe ditch is provided with an insulating plate, and the fireproof sandbags are placed in layers to ensure that cable protection measures are in place and ensure the implementation safety of the pipe ditch cable;

2. the electric power pipe trench concrete structure is dismantled in blocks by adopting a vibration-free rope saw, the electric power cable is integrally suspended by adopting a steel truss structure, and the support point of a steel truss continuous beam adopts a lattice column and a steel beam, so that the detailed processing of the support column structure and the station structure is ensured to be in place, and the suspension safety of a large-span steel truss is also ensured;

3. in the aspect of construction period, the power pipe trench suspension protection has great advantages compared with moving and modifying, the cutting, moving and modifying period is more than 1 year according to the similar engineering construction experience of the conventional subway, and the moving and modifying cost is quite high. The integral suspension protection scheme is adopted, the construction period is about 3 months, and the cost is about 1/4 of the replacement cost;

4. the steel truss is adopted to realize the suspension of the large-span ultrahigh-voltage power pipe ditch, the uninterrupted operation and construction can be realized, the power supply of the power pipeline power supply range in a construction area is ensured, the economic loss caused by power failure is avoided, the economic benefit and the social benefit are remarkable, and the universal applicability and the popularization are realized.

Drawings

The invention is further illustrated by the following examples in conjunction with the accompanying drawings:

fig. 1 is an overall structural view of a suspension device of the present invention;

FIG. 2 is a schematic view of step3-5 installation in the construction method of the present invention;

FIG. 3 is a schematic view of step7.1 middle frame dismantling in the construction method of the present invention;

FIG. 4 is a schematic view showing the removal of a top cover in step7.2 in the construction method of the present invention;

FIG. 5 is a schematic view showing the removal of the side wall in step7.3 in the construction method of the present invention;

FIG. 6 is a schematic view of the connection structure of lattice column and cast-in-place pile of the present invention;

FIG. 7 is a schematic view of installation of cables in a 9 steel structure truss according to the invention;

FIG. 8 is a schematic view of the connection of the suspension device to the foundation pit structure according to the present invention;

fig. 9 is a schematic view of the installation of the step2 explosion-proof box of the invention.

Wherein: the electric power pipe ditch comprises an electric power pipe ditch 1, a steel structure truss 2, a steel main beam 21, a steel cross beam 22, a chord 23, a steel truss cable support 24, a lattice support 3, a cast-in-place pile 4, a bearing platform foundation 5, a lattice column 6, a supporting cross beam 7, a cable 8, an MPP electric power protection pipe 9, an insulation bottom plate 10, a fireproof sand bag 11, a fireproof plate 12, an electric power pipe ditch cable support 13, a grounding flat iron 14, a top cover lifting hole 15, a top cover cutting line 16, a side wall cutting line 17, a foundation pit 18, a foundation pit edge protection support 19, a foundation pit cross brace 20, a steel main beam 21, a steel cross beam 22, a chord 23 and a cable support 24.

Detailed Description

The technical scheme of the invention is explained in detail in the following by combining the drawings and the embodiment.

As shown in fig. 1, large-span superhigh pressure power pipe ditch suspension device in subway station foundation ditch, including the steel construction truss 2 that power pipe ditch 1 connects, steel construction truss 2 both sides and excavation supporting crown beam suspend in midair and be connected, in steel construction truss 2 both ends stretch into power pipe ditch 1, be provided with a plurality of lattice supports 3 along steel construction truss 2 directions, lattice support 3 and the contact of steel construction truss 2 lower extreme, lattice support 3 lower extreme and foundation ditch ground basis fixed connection, the cable is placed in power pipe ditch 1 and steel construction truss 2, the whole weight of cable and steel construction truss 2 is born jointly by a plurality of lattice supports 3, steel construction truss 2 lower part and lattice support 3, the space that the foundation ditch formed is used for the construction.

And a force transmission steel plate is arranged at the bottom of the part of the steel structure truss 2 extending into the power pipe ditch 1.

Besides adopting a linear form, the steel structure truss 2 can also adopt a lattice support 3 to carry out sectional support according to the branched structure of the power pipe trench 1 to carry out a middle branched structure.

As shown in fig. 1, the steel truss 2 is formed by arranging four steel main beams 21 in parallel along a rectangle or a square, the steel main beams 21 are fixedly connected by steel cross beams 22, the steel cross beams 22 are fixedly connected end to end by oblique chords 23, the two steel main beams 21 at the upper end are suspended and connected with a foundation pit supporting crown beam, and a steel truss cable support 24 for fixing cables is arranged in the steel truss 2.

The arrangement interval of the cross beams is 2m, the maximum length of a single span of the steel structure truss is 20-25 m, and the total length can be selected according to the actual use condition of the engineering.

As shown in fig. 7, the steel main beams 21 and the steel cross beams 22 are H-shaped steel beams.

As shown in fig. 1 and 6, the lattice support 3 includes two lattice columns 6 and two filling piles 4 which are fixedly connected from top to bottom, the lower end of the filling pile 4 is fixedly connected with the foundation of the foundation pit ground, the two lattice columns 6 and the two filling piles 4 are respectively arranged on two sides of the steel structure truss 2, the two lattice columns 6 are fixedly connected by a supporting beam 7, the lower end of the steel structure truss 2 is placed on the supporting beam 7, and the upper ends of the two filling piles 4 are fixedly connected by a bearing platform foundation 5.

As shown in fig. 6, the lower end of the lattice column 6 is embedded into the cast-in-place pile 4 and poured together to form a whole, the lattice column 6 is formed by welding angle steel and steel plate lacing strips, and the length of the inserted foundation of the lattice column 6 is 3 m.

As shown in fig. 8, the steel structure truss 2 is formed by continuously connecting a plurality of sections of spliced steel main beams 21, the single span is 20-25 m, the lattice supports 3 are supported at the spliced position, and the foundation pit supporting structure of the power pipe trench 1 is supported by steel grids and sprayed concrete.

As shown in fig. 2 to 9, the suspension construction method using the large-span ultra-high voltage power pipe trench suspension device in the foundation pit of the subway station specifically comprises the following steps:

step1, finding out the specific conditions of high voltage and cables in the power pipe trench 1 in the range of the station foundation pit, drawing a cable distribution diagram, marking the risk of cable moving, and marking the length and the range of the power pipe trench 1 to be suspended;

step2, installing an explosion-proof box at the joint position of the cable in the power pipe trench 1, filling the explosion-proof box with fireproof mud, and performing insulation treatment;

step3, installing an insulating bottom plate 10 at the bottom of the power pipe trench 1, and paving the insulating bottom plate 10, namely the bottom layer of the cable, with a fireproof sandbag 11;

step4, wrapping and protecting the cable by using an MPP power protection pipe 9, and plugging ports at two ends of the cable protection pipe by using fireproof mud;

step5, performing layered protection on the cable by using a fireproof sand bag 11, flatly laying a layer of fireproof sand bag 11 on the MPP power protection pipe 9 of the topmost cable, and flatly laying a fireproof plate 12 on the upper part;

step6, constructing a lattice column 6 and a foundation cast-in-place pile 4 of the lattice column 6 at the suspension supporting part of the power pipe trench 1;

step7, performing protective dismantling on the power pipe trench 1 concrete structure needing to be suspended;

step8, manufacturing and installing a steel structure truss 2 around the protected cable, wherein two sides of the steel structure truss 2 are connected with a foundation pit supporting crown beam in a suspension mode, the lower end of the steel structure truss 2 is supported by adopting lattice columns 6 and supporting cross beams 7, and a grounding device of the steel structure truss 2 is installed;

and Step9, laying the cables in the steel truss cable bracket 24 in layers according to voltage levels and fixing the cables by using a bandage.

After the construction in the foundation pit is completed, the restoration steps of the power pipe trench 1 are as follows:

step10, after the foundation pit construction is completed and the top plate is backfilled to the bottom of the steel structure truss 2, bedding and laying of a bottom plate and a fireproof sand bag 11 are carried out on the bottoms of the power pipe trench 1 and the steel structure truss 2, the truss bottom chord members 23 are removed, and cables fall to the ground in a layered mode;

step11, removing the steel structure truss 2, cutting off the latticed supports 3 in sections, pouring the removed power pipe trench 1 again before restoration, and completing the restoration of the cable.

As shown in fig. 3-5, the specific steps of Step7 are as follows:

step7.1, cutting a cable support, connecting and grounding a power pipe trench cable support 13 in the power pipe trench 1 through a grounding flat iron 14, then cutting off the support, and taking fireproof, antistatic and ventilation measures when cutting off the support;

step7.2, cutting a top cover, drilling a hole in the top cover of the power pipe trench 1 to be detached, drilling the hole through the hole to form a top cover lifting hole 15, scribing a top cover cutting line 16 along the upper end of the side wall of the power pipe trench 1 to be detached, carrying out static cutting on the concrete structure of the power pipe trench 1 along the top cover cutting line 16, and lifting and transferring the cut top cover by using the top cover lifting hole 15 after the cutting is finished;

step7.2, cutting the side wall, marking a side wall cutting line 17 at the lower end of the side wall of the power pipe trench 1 to be dismantled, carrying out static cutting on the concrete structure along the side wall cutting line 17, and removing the cut side wall after cutting.

Pouring construction is carried out on the power pipe trench 1 restored and detached in the Step11 according to the sequence of the bottom plate, the side wall and the top plate, the top plate of the pipe trench is made of small assembled customized steel templates, and restoration work comprises civil construction grounding of the pipe trench and installation of a cable support.

As shown in fig. 8, the foundation pit 18 lies in that the junction of the electric power pipe ditch 1 adopts the steel structure truss 2, the upper end of the steel structure truss 2 is suspended and connected with the foundation pit support crown beam, the lower end of the steel structure truss 2 adopts the lattice support 3 to support, the foundation pit 18 is enclosed by the foundation pit edge support pillar 19, the foundation pit edge support pillar 19 both ends crown beam adopts the foundation pit cross brace 20 to support, the lattice support 3 area under the steel structure truss 2 is very small, the construction influence in the foundation pit is very small, the steel structure truss 2 is to high pressure, the supporting effect and the installation of super high voltage cable can be carried out under the condition of not cutting off power, the influence on the foundation pit and the power consumption is small, and the subway construction method is suitable for being popularized and used in the subway construction field.