阅读说明：本技术 一种地铁出入口兼做始发井的顶管施工方法 (Pipe jacking construction method taking subway entrance and exit as starting well ) 是由 王凌 陈盼元 张跃明 朱正宜 梁剑 史策辉 傅雅莉 钟彦之 潘伟波 张文正 朱碧 于 2020-12-31 设计创作，主要内容包括：本发明公开了一种地铁出入口兼做始发井的顶管施工方法,针对地铁线某站1的施工项目,该主体结构车站主体结构总长约252.45m,站台宽度11m,标准段宽19.9m,车站为单柱双跨地下两层岛式车站,覆土约4m左右,共设4个出入口和2组风亭,4号出入口分为4a出入口2和4b出入口3,4号出入口下穿某北路5,某北路5交通繁忙,道路下方管线交错密集复杂,为减少对交通的影响,下穿某北路5的4号出入口通道采用顶管法施工。本发明解决现有技术中顶管施工方法工期过长,难免多次施工的问题。(The invention discloses a pipe jacking construction method taking a subway entrance and exit as an initial well, aiming at the construction project of a station 1 of a subway line, the main structure of the station has the advantages that the total length of the main structure of the station is about 252.45m, the width of a platform is 11m, the standard section width is 19.9m, the station is a single-column double-span underground two-layer island type station, soil is covered for about 4m, 4 entrances and exits and 2 groups of shelters are arranged in total, the No. 4 entrance and exit is divided into an entrance and exit 2 and an exit 3 of 4a, a No. 4 entrance and exit pass through a certain north road 5 downwards, the traffic of the certain north road 5 is busy, the pipelines below the road are staggered and dense and complex, and the No. 4 entrance and exit channel passing through the certain north road 5 downwards. The invention solves the problems that the construction method of the jacking pipe in the prior art is overlong in construction period and is difficult to avoid multiple constructions.)

1. A pipe-jacking construction method taking a subway entrance and an exit as an initial well is characterized by comprising the following steps:

and an originating well is not independently arranged, the originating well is jointly built with an access, and other areas of the internal structure of the main body are completed before pipe jacking construction.

2. The pipe jacking construction method of claim 1, wherein before the pipe jacking construction method is implemented, the method comprises the following steps:

checking the implementation condition of a soil baffle on a top plate at a main body interface of a subway station foundation pit to ensure that the implementation condition is implemented as required, and performing construction of an auxiliary crown beam and a first support after rechecking the spatial relationship between a main body enclosure structure and an auxiliary access enclosure structure;

excavating a subway station foundation pit main body, sequentially erecting supports until reaching a base, and constructing a cushion layer;

and step three, constructing an auxiliary bottom plate, a side wall, an internal plate and a top plate according to the auxiliary main body process so as to finish the construction of the No. 4 access and foundation pit main body interface.

3. The pipe jacking construction method of claim 2, wherein the pipe jacking construction method comprises the following steps: and starting pipe jacking construction by using a pipe jacking machine, and installing a prefabricated pipe joint in the auxiliary main body structure.

4. The pipe jacking construction method of claim 1, wherein a pipe jacking machine is placed in the subway entrance and exit, the pipe jacking machine is positioned on a back rest of the entrance and exit, steel supports on two sides respectively prop against the side walls of the entrance and exit, and a lower oil cylinder directly props against a beam.

5. The pipe jacking construction method taking a subway entrance as an initial well according to claim 1, wherein the pipe jacking machine parameters are calculated according to the following two parts:

a. calculating the bearing capacity of the steel support;

b. and calculating the stress of the originating frame and the receiving frame.

Technical Field

The invention belongs to the technical field of subway station construction, and particularly relates to a pipe jacking construction method taking a subway entrance and exit as an initial well.

Background

At present, the traditional pipe jacking method is that a starting well is constructed firstly, and then the rest of internal structure enclosure structures are completed after the pipe jacking is completed, the construction of the starting well area firstly, then the pipe jacking is constructed, and then the rest of internal structure enclosure and internal structures are completed after the pipe jacking is completed. In the process of jacking pipe pushing, the back of the temporary inner wall needs to be additionally provided with a steel support, the steel support directly transmits the jacking force of the jacking pipe to the back wall, and the deformation of the temporary inner wall in the process of jacking the pipe is avoided being too large.

However, the pipe jacking construction method in the prior art inevitably causes repeated construction, and easily causes overlong construction period.

Disclosure of Invention

The invention provides a pipe-jacking construction method taking a subway entrance and exit as an initial well, which aims to solve the problems that the pipe-jacking construction method in the prior art is too long in construction period and is difficult to avoid multiple constructions.

The technical scheme of the invention is realized as follows:

a pipe jacking construction method taking a subway entrance and an exit as an initial well comprises the following steps:

the method comprises the steps that firstly, a subway station foundation pit comprises a main body structure and an access auxiliary structure, the implementation condition of a soil baffle plate on a top plate at a main body interface is checked, the implementation condition of the soil baffle plate is ensured to be implemented as required, and after the space relation between a main body enclosure structure and the auxiliary enclosure structure is rechecked, an auxiliary crown beam and a first support are implemented.

And step two, excavating a foundation pit, sequentially erecting supports till the foundation and constructing a cushion layer.

And step three, constructing an auxiliary bottom plate, a side wall, an inner plate and a top plate according to the auxiliary main body process so as to finish the construction of the main body interface.

And fourthly, performing pipe jacking construction through the auxiliary main body structure.

Preferably, in the fourth step, the pipe jacking construction into the auxiliary body structure includes: and starting pipe jacking construction by using a pipe jacking machine, and installing a prefabricated pipe joint in the auxiliary main body structure.

Preferably, before the fourth step, other areas of the internal structure of the auxiliary construction main body are constructed.

The invention has the beneficial effects that:

1) by adopting a combined construction mode, the construction period can be saved while the safety and the reliability of the structure are ensured, and multiple times of staging construction are avoided;

2) because the pipeline under the road is staggered and dense, the influence on traffic is reduced.

Drawings

FIG. 1 is a schematic plan view of the construction of the entrance and exit jacking pipes of the present invention;

FIG. 2 is a plan view of the pipe jacking origination and reception of the present invention;

FIG. 3 is a side cross-sectional view of the push pipe launch and receive north of the present invention;

figure 4 is a side cross-sectional view of a push pipe launch and receive south of the present invention;

FIG. 5 is a cross-sectional view of the push bench of the present invention;

FIG. 6 is a block diagram of an origin rack of the present invention;

FIG. 7 is an enlarged view of a portion of FIG. 1 at A;

fig. 8 is a partially enlarged schematic view of a portion B in fig. 1.

In the figure: the system comprises an access 2 of a certain station 1 and an access 4a, an access 3 of a certain station 4b, a certain north road 5, a first-way support 6, a push bench 7, a steel support 8, a civil air defense door 9 and a back rest 10.

Detailed Description

The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

Example 1

Aiming at the construction project of a certain station 1 of the subway line, the main structure of the station has the total length of 252.45m, the platform width of 11m and the standard section width of 19.9 m. The station is a single-column double-span underground two-layer island type station, the soil is covered by about 4m, and 4 entrances and exits and 2 groups of shelters are arranged. The No. 4 doorway is divided into a 4a doorway 2 and a 4b doorway 3. As shown in fig. 1, a No. 4 entrance passes through a certain north road 5, the traffic of the certain north road 5 is busy, the pipelines below the roads are staggered and dense, and in order to reduce the influence on the traffic, a No. 4 entrance channel passing through the certain north road 5 is constructed by a pipe jacking method.

The construction of the entrance and exit of the project is specifically shown in fig. 1, and specifically comprises the following construction steps:

checking the implementation condition of a soil baffle on a top plate at a main body interface of a subway station foundation pit, ensuring that the implementation is carried out according to requirements, and after rechecking the spatial relationship between a main body enclosure structure and an auxiliary access enclosure structure, constructing an auxiliary crown beam and a first support 6;

excavating a subway station foundation pit main body, sequentially erecting supports until reaching a base, and constructing a cushion layer;

constructing an auxiliary bottom plate, a side wall, an inner plate and a top plate according to an auxiliary main body process so as to finish the construction of a No. 4 access and foundation pit main body interface;

and step four, pipe jacking construction is carried out by taking the No. 4 access as an originating well.

As a preferred scheme, the step four of pipe jacking construction by taking the No. 4 access as an initial well comprises the following steps: and (5) starting pipe jacking construction by using a pipe jacking machine 7, and installing the prefabricated pipe joints in the auxiliary main body structure. The other areas of the internal structure of the entrance and exit No. 4 are completed before the step four is performed.

As a preferred scheme, the construction of the inner jacking pipe in the fourth step is as shown in fig. 1 to 4, the pipe jacking machine starts at a 4-b well mouth and receives at a 4-a well mouth, the pipe jacking machine 7 is propped against a back backrest 10, then the steel supports 8 are used for transmitting the counter force to the side walls, 3 steel supports 8 are respectively used at two sides of the pipe jacking machine 7, the north side penetrates through a civil air defense door 9 and directly props against the wall, and the south side steel supports 8 directly prop against the civil air defense wall. In the embodiment of the invention, the push bench has 14 oil cylinders, the maximum pressure of each oil cylinder reaches 200t, the two sides are respectively provided with 14 oil cylinders, the lower part has 6 oil cylinders, the two sides have 8 oil cylinders, the details are shown in figure 5, the two sides respectively use phi 609 steel supports 8 to transmit force to the side walls, and the lower part has 6 oil cylinders to directly support the beam. Steel supports 8 on two sides of a push bench 7 are steel supports 8 with the thickness of phi 609 being 16mm, according to calculation of a design institute, a force of 3000T is needed by the ground layer without considering a drag reduction effect, the push bench has 14 oil cylinders, each oil cylinder needs thrust of about 215T, 4 oil cylinders on each side have 860T, 3 steel supports on each side bear 860T, and each steel support 8 needs 287T. The calculation result according to the rational structure design is as follows:

a. calculation of steel support bearing capacity

1. Inputting data

1.1 basic input data

Material properties of structural member

Material name Q235

Maximum thickness of the member section 16.00(mm)

Design strength 215.00(N/mm2)

Yield strength 235.00(N/mm2)

Cross sectional property

Section name seamless steel pipe d =600(mm)

The external diameter of the seamless steel tube [2t is less than or equal to d ] is 600(mm)

The wall thickness of the seamless steel tube (t is more than 0 and less than or equal to d/2) is 16 (mm)

Type of patch:

height of component 10.600(m)

Permissible strength safety factor of 1.00

Permissible stability safety factor of 1.00

1.2 load information

Constant load fractional coefficient of 1.30

Coefficient of live load component 1.40

Live load adjustment coefficient of 1.00

Whether the dead weight is considered

Axial constant load standard value 4000.000(kN)

Axial live load standard value of 0.000(kN)

Eccentric distance Ex of 0.0(cm)

Eccentric distance Ey 0.0(cm)

1.3 connection information

Connection mode of ordinary connection

Whether the cross section is weakened, whether

1.4 end constraint information

Top constraint type in X-Z plane simple support

Type of bottom constraint in X-Z plane-simple support

Length coefficient calculated in X-Z plane 1.00

Top constraint type in Y-Z plane-simple support

Type of bottom constraint in Y-Z plane-simple support

Length coefficient calculated in Y-Z plane 1.00

2 intermediate results

2.1 Cross-sectional geometry

Area 293.55(cm2)

Moment of inertia Ix 125240.37(cm4)

Moment of resistance Wx 4174.68(cm3)

Radius of gyration ix 20.66(cm)

Moment of inertia Iy 125240.37(cm4)

Moment of resistance Wy:4174.68(cm3)

Radius of gyration iy 20.66(cm)

Coefficient of plastic development γ x1:1.15

Coefficient of plastic development γ y1:1.15

Coefficient of plastic development γ x2:1.15

Coefficient of plastic development γ y2:1.15

2.2 Material Properties

Tensile Strength 215.00(N/mm2)

Compressive strength 215.00(N/mm2)

Bending Strength 215.00(N/mm2)

Shear strength 125.00(N/mm2)

Yield strength 235.00(N/mm2)

Density of 785.00(kg/m3)

2.3 stabilization of information

Bending around the X axis:

slenderness ratio λ x =51.32

Class a of cross-sectional classification (in terms of compressive characteristics) of axial compression member

Phi x =0.912 as the whole stability coefficient of the axle center under pressure

Minimum stability factor of safety 1.11

Maximum stability safety coefficient of 1.11

Distance from the section to the top end of the member corresponding to the minimum stability safety factor 10.600(m)

The distance from the section to the top end of the member, which corresponds to the maximum stability safety factor, is 0.000(m)

The most unfavorable position of the stress stabilized around the X axis is according to the formula of Steel Structure Specification (5.1.2-1)

Bending around the Y axis:

slenderness ratio λ y =51.32

Class a of cross-sectional classification (in terms of compressive characteristics) of axial compression member

Phi y =0.912 as the whole stability coefficient of the axle center under pressure

Minimum stability factor of safety 1.11

Maximum stability safety coefficient of 1.11

Distance from the section to the top end of the member corresponding to the minimum stability safety factor 10.600(m)

The distance from the section to the top end of the member, which corresponds to the maximum stability safety factor, is 0.000(m)

The most unfavorable position of the stress stabilized around the X axis is according to the formula of Steel Structure Specification (5.1.2-1)

3. Analysis results

The member is in a safe state, stable and meets the requirements, and the strength meets the requirements.

b. Calculation of stress of originating and receiving frames

1. Calculation of rail strength

As shown in fig. 6, is an originating rack structure. The self weight of the push bench is about 290t, the length of the push bench is 4.55m, 2 steel rails are arranged on one side of an initial frame, and each F1= F2= F3= F4=159.34KN/m after conversion; the theoretical bearing pressure 387KN/m of the steel rail is larger than 159.34 KN/m. Therefore, the strength of the steel rail meets the requirement.

2. Checking calculation of stress of base of launching cradle

The weight of the shield machine is mainly distributed at four positions of a cutter head, a front shield, a middle shield and a shield tail, wherein the weight of the cutter head is about 58t, the weight of the front shield is about 102t, the weight of the middle shield is about 102t, and the weight of the shield tail is about 35t, which are counted together: 297 t.

2.1 design load of the push bench:

design value of bending strength of steel: 215N/mm Q235 steel

Pressure of the pipe jacking machine: f =185kN/m

Load is uniformly distributed: q = F × 0.785/1000=235(N/m)

2.2 starting frame cross section coefficient:

looking up a table to know; the carrying surface of the H-shaped steel is characterized in that: ix =10800cm4, Iy =365cm4, and Wx =867cm 3.

2.3 starting frame bending strength checking calculation:

M=0.185qI²=0.185×235×0.785²=26.79N·m

bending resistance load-bearing capacity σ = M/M =0.185q1=26.79/867 × 103=30.1N/mm < 215N/mm.

2.4 starting frame deflection checking calculation:

ω=0.677×q14/100EI

=0.677×235×0.7854/100×2.06×104×10800×10=0.27mm。

2.5 conclusion

The bending resistance and the flexibility of the bases of the originating frame and the receiving frame meet the requirements.

Compared with the traditional pipe-jacking construction method, the construction method of the invention can save the construction period, avoid multiple times of staged construction, ensure the structure to be safe and reliable, and improve the construction effect of pipe-jacking construction, has better popularization significance, and the above description is only a preferred embodiment of the invention, and is not used for limiting the invention.