CN112922035A

CN112922035A - Reverse construction method for contact channel structure of subway open cut section

Info

Publication number: CN112922035A
Application number: CN202110133842.4A
Authority: CN
Inventors: 曹富荣; 石艳军; 白文博; 王振坤; 张侃; 冷珍华; 谢文璐; 郭二涛
Original assignee: China Gezhouba Group Municipal Engineering Co ltd
Current assignee: China Gezhouba Group Municipal Engineering Co ltd
Priority date: 2021-02-01
Filing date: 2021-02-01
Publication date: 2021-06-08
Anticipated expiration: 2041-02-01
Also published as: CN112922035B

Abstract

The invention discloses a reverse construction method for a subway open cut interval contact channel structure, which sequentially comprises the following steps: construction preparation, excavation of a foundation pit, bottom of a main line, a main line bottom plate, a main line side wall, a connecting channel side wall, a field entrance and exit line bottom plate, a field entrance and exit line top plate, excavation of earth of a water collecting pool, treatment of construction joints, a water collecting pool bottom plate, a water collecting pool side wall, a connecting channel bottom plate, a water pool cover plate, a fireproof door and a waterproof sleeve plugging book; the construction method is characterized in that the side wall of the contact channel is constructed firstly, then the bottom plate of the contact channel is constructed, and different from the traditional open cut process, the foundation pit structure is stabilized by the advanced construction of the side wall of the contact channel, and the water collecting tank excavation and the structure construction at the position of the contact channel are arranged to alternate with the track laying operation at the later stage to be constructed, so that a non-key line is formed, the smooth completion of construction nodes is effectively ensured, and a certain time is saved for subway construction engineering.

Description

Reverse construction method for contact channel structure of subway open cut section

Technical Field

The invention belongs to the technical field of urban rail transit, and particularly relates to a reverse construction method for a contact channel structure of an open cut area of a subway.

Background

Along with the rapid development of urban rail transit, open cut method construction is increasingly applied to a plurality of suburb combined areas, when sandy gravel layer earthwork excavation is carried out, a foundation pit is influenced by underground water and is not suitable for forming, the construction efficiency is low, and when excavation is carried out near a building enclosure, the pile body is hollowed out due to underground water scouring, and great potential safety hazards can be caused. When an open cut interval (including an entrance field line) is located in the middle and crosses a positive line interval to carry out transition, an island is formed at the position of a communication channel, the structure is located in a sandy gravel stratum, and because the height of the base of the communication channel and a waste water pump room is designed to be lowest, peripheral underground water is gathered in a concentrated mode, the phenomenon of water inrush and sand inrush is very easy to occur during earthwork excavation, the buried depth of a water collecting tank is below the structure of a bottom plate, the scouring phenomenon in the excavation process is more serious, the construction risk is very high by adopting a sequential method, the treatment cost is higher by adopting a dewatering well dewatering or freezing method, the construction period is long, and the subsequent construction plan is seriously influenced, so that the reasonable construction method is researched to ensure the safety of a foundation pit, and the construction period can.

Disclosure of Invention

The invention aims to solve the technical problems that when an island working surface is formed at the position of an access line on an access line at an open cut section of a subway, the safety risk is high when sand aquifer earthwork excavation is carried out, the cost for treating underground water is high, and construction nodes are difficult to guarantee in the traditional construction method.

In order to solve the technical problems, the technical scheme adopted by the invention is as follows: a reverse construction method for a subway open cut interval connection channel structure comprises the following steps:

s1, excavating a foundation pit, and after the excavation is finished, constructing a main line bottom plate in the small foundation pit; then constructing a main line side wall and a connecting channel side wall, and respectively arranging horizontal construction joints on a main line bottom plate and the connecting channel side wall;

s2, constructing an entrance and exit field line bottom plate above the main line side wall and the communication channel side wall, and constructing an entrance and exit field line top plate above the entrance and exit field line bottom plate;

s3, arranging a plurality of grouting floral tubes at the periphery of a water collecting pool area with a preset plan for grouting reinforcement; then, carrying out earth excavation of the water collecting pool, and then treating the construction joint; constructing a bottom plate and side walls of the water collecting tank in sequence after excavation; constructing a connection channel bottom plate after constructing the pool structure, and finally constructing a water collecting pool cover plate and a fireproof door;

and S4, plugging the waterproof sleeves reserved on the entrance and exit field line bottom plate and the entrance line top plate, and finishing construction.

Preferably, in step S, before the construction of the main line bottom plate, the construction of the cushion layer, the waterproof layer and the protective layer of the main line bottom plate is completed, and a horizontal construction joint is arranged at the joint of the main line bottom plate and the communication channel bottom plate.

Preferably, the horizontal construction joint comprises the following specific construction steps:

A. positioning and paying off on the waterproof protection layer of the bottom plate, reserving a main body steel bar, and installing a back-attached water stop belt, wherein the exposed length of the main body steel bar is 50 cm;

B. mounting a lower template of the construction joint, and sticking a sealing rubber strip at the bottom of the lower template of the construction joint; 5-10 cm vertical battens are installed in close contact with the lower formwork, and 10-10 cm transverse battens are installed in close contact with the vertical battens;

C. installing a water stop steel plate at the bottom of the lower formwork of the construction joint; the water stop steel plate takes the template as the center, and the same width of the two sides is 15 cm;

D. installing a construction joint upper-layer template on the water stop steel plate, wherein the construction method of the construction joint upper-layer template is consistent with that of the construction joint lower-layer template;

E. vertically installing positioning ribs along two sides of the template, and welding the positioning ribs and the embedded steel bars for fixing the template and the water stop steel plate;

F. the diagonal bracing steel bars are arranged on the outer side of the template, and two ends of the diagonal bracing steel bars are welded with the positioning bars and the embedded steel bars respectively to prevent the template and the water stop steel plate from moving.

Preferably, in step S2, before the construction of the main line side wall, the dismantling of the third layer of steel support of the foundation pit and the waterproofing construction of the side wall are completed; before the construction of the side wall of the connection channel, a horizontal construction joint is arranged at the bottom of the side wall of the connection channel.

A. excavating a groove with the depth of 30cm and the width of 5cm along the inner side of the side wall of the communication channel;

B. laying a waterproof coiled material from the groove, and after laying is finished, placing a foam board with the thickness of 15mm in close contact with the waterproof coiled material in the groove;

C. installing and fixing a back-attached water stop belt on the surface of the foam plate, and filling the groove with fine sand;

D. after measurement and positioning, inserting embedded steel bars and a water stop steel plate, and pouring a C20 cushion layer with the thickness of 100mm for fixing.

Preferably, in step S2, a250 waterproof sleeve is pre-embedded in the floor of the entrance and exit field line and the roof of the entrance and exit field line, so as to facilitate drainage during later concrete pouring and excavation.

Preferably, in step S3, before the sump earthwork is excavated, the scaffold is removed and cleaned, and then grouting reinforcement and layered excavation are performed, wherein the excavation depth of each layer is not greater than 1 m.

Preferably, in step S3, the concrete steps of grouting reinforcement are as follows:

A. according to the position required by the scheme, the grouting floral tubes are driven into the injected layer position at a certain angle along the periphery of the water collecting tank; the driving direction is inclined by 12 degrees;

B. controlling grouting according to the designed grouting amount and grouting pressure, and plugging the pipe orifice after grouting is finished;

C. d7, excavating the earthwork of the water collecting pool, excavating an A25 anchor rod with the length of 1.2m along with the excavation, hanging a wire mesh, mixing with cement mortar and plastering, and adding 0.5 percent of an accelerating agent into the mortar;

D. arranging a water drainage hole at a position with large water seepage, adopting a PVC (A32) pipeline to be arranged along a slope with an inclination of 5 percent, wrapping the exterior of the PVC pipeline by using a permeable non-woven fabric, and arranging a water collection pit in the foundation pit for pumping and draining.

Preferably, in step S3, the construction joint treatment is performed after the first layer of earth excavation is completed, the construction joint is roughened by an air pick, the water-stopping steel plate is brushed by a steel wire brush, and finally the construction joint is washed clean by clean water.

Preferably, in step S4, the waterproof sleeve is filled with high-grade fine aggregate concrete, the upper and lower ends are welded and sealed by galvanized steel plates, after the top is welded, the waterproof sleeve is leveled by mortar, and a waterproof coating is applied and a waterproof protective layer is poured.

The reverse construction method for the contact channel structure of the subway open cut area has the following beneficial effects:

(1) according to the construction method, the side wall of the communication channel is constructed firstly, so that the deformation of the post-wall pile body and the foundation pit is effectively inhibited, the construction risk of earth excavation near an island working surface is greatly reduced, and the safety of the foundation pit is ensured;

(2) after the construction of the side wall of the contact channel is finished, the construction of the interval main line structure and the entrance and exit field line structure sides is started, the construction time of the bottom plate and the water collecting tank of the contact channel structure is arranged on a non-critical line, and the alternate operation is carried out with the track laying construction, so that a certain time is saved, and the node construction period of civil construction is effectively ensured;

(3) the construction method adopts a reverse construction method, effectively reduces the safety risk of the earth excavation of the water collecting pool, does not need to adopt construction measures such as precipitation or freezing method and the like as the same construction of a sequential construction method, and effectively controls the construction cost;

(4) the construction joint waterproof construction and treatment method adopted by the construction method effectively ensures the construction quality of the outer waterproof layer and the waterproof construction quality of the construction joint structure, and avoids the occurrence of quality hidden troubles such as structure leakage caused by insufficient treatment measures.

Drawings

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

FIG. 1 is a process flow diagram of the construction method of the present invention;

fig. 2 is a schematic plan view of the foundation pit of the present invention.

FIG. 3 is a schematic cross-sectional view of the structure of the present invention.

FIG. 4 is a schematic view of a horizontal construction joint of a base plate according to the present invention.

FIG. 5 is a schematic view of a horizontal construction joint of a sidewall of the present invention.

Fig. 6 is a schematic view of the sump grouting reinforcement of the present invention.

The reference numbers in the figures are: the outer soil body 1 of foundation ditch, big foundation ditch fender pile 2, main line side wall 3, little foundation ditch fender pile 4, little foundation ditch foundation 5, concrete bracing 6, contact passageway side wall 7, catch basin 8, main line bottom plate 9, field line bottom plate 10 of cominging in and going out, field line roof 11 of cominging in and going out, catch basin apron 12, catch basin bottom plate 13, catch basin side wall 14, contact passageway bottom plate 15, prevent fire door 16, construction joint lower floor's template 171, construction joint upper formwork 172, location muscle 18, bracing reinforcing bar 21, vertical flitch 191, horizontal flitch 192, embedded reinforcing bar 20, bracing reinforcing bar 21, reinforcing bar welding seam 22, sealed glue 23, back of the body formula waterstop 24, stagnant water steel sheet 25, waterproofing membrane 26, foam board 27, slot 28, bed course 29, slip casting pipe 30, rigidity waterproof jacket 31.

Detailed Description

As shown in fig. 1 to 6, a reverse construction method of a connection channel structure in an open cut area of a subway comprises the following steps:

D. after the measurement location, insert embedded steel and stagnant water steel sheet, stagnant water steel sheet is placed between two parties, buries bed course and soil body 150mm, then pours the C20 bed course of 100mm thick and fixes.

Preferably, in step S2, a250 waterproof sleeve is pre-embedded in the floor of the entrance and exit field line and the roof of the entrance and exit field line, so as to facilitate drainage during later concrete pouring and excavation; the waterproof sleeve pipe is exposed from the upper part and the lower part of the structure surface by 10cm, and a drain pipe and a concrete chute can penetrate through the sleeve pipe in the construction process so as to facilitate construction.

Preferably, in step S3, before the sump earthwork is excavated, the scaffold is removed and cleaned, and then grouting reinforcement and layered excavation are performed, wherein the excavation depth of each layer is not more than 1 m; grouting pipes (A42 multiplied by 4 mm) are adopted, the length of each pipe is 2m, and grouting reinforcement is carried out in two layers.

B. controlling grouting according to the designed grouting amount and grouting pressure, wherein the grouting pressure is 0.3-0.8 MPa, performing a test before grouting to determine that the relationship between the grouting amount and the allowable grouting pressure provides reference, and plugging the pipe orifice after grouting is finished;

Preferably, in step S4, filling high-grade fine aggregate concrete into the waterproof sleeve, welding and sealing the upper and lower ends with galvanized steel plates, after the top is welded, leveling with mortar, painting waterproof paint and pouring a waterproof protective layer; after the structure construction is accomplished, beat and establish simple and easy scaffold frame, successively carry out the shutoff with the waterproof sleeve pipe of entrance and exit field line bottom plate and roof, fill the fine aggregate concrete of high designation C40 in waterproof sleeve pipe inside, upper and lower both ends are with galvanized steel sheet (30 x 30cm, t =3 mm) welded seal, after the top welding is accomplished, trowel with the mortar, apply paint with a brush single component polyurethane waterproof coating, the scope of applying paint with a brush is 50cm x 50cm, thickness is 2.5mm, divide 3 layers to apply paint with a brush and accomplish, pour 100mm thick C20 waterproof layer.

The material selection described in the examples is as follows:

1. water stop steel plate: the water stop steel plate is processed by a professional manufacturer, and the water stop steel plate material entering the field is checked whether the certificate, the quantity, the specification quality, the technical index, the main mark and the like meet the requirements or not, and the water stop steel plate material does not meet the material standard and is forbidden to be used; the water stop steel plate adopts double-sided welding, and ignition and arc striking are strictly prohibited on steel materials outside a welding seam so as to avoid damaging base materials. The welding seam metal surface is welded evenly, and the defects of cracks, slag inclusion, welding beading, burn-through, isolated pits, needle-shaped air holes and the like are avoided, and the spatter at the welding position is removed, so that the quality of all welding seams is ensured to meet the standard requirement.

2. Waterproof roll material: the asphalt-based polyester tire waterproof coiled material (PY type) is a double-sided self-adhesive coiled material, and the thickness is not less than 4 mm. In the inspection procedure of material entering the field, a material worker, a constructor and a quality inspector strictly inspect the material according to corresponding regulations, and sample the material to perform retesting under the condition of on-site evidence of supervision according to test requirements, so that the material which does not meet the requirements cannot be used in the project.

3. The grouting perforated pipe is made of 35CrMo steel, and whether the quantity, the specification quality, the quality policy, the detection report, the technical condition, the main mark and the like meet the requirements or not and do not meet the strict use prohibition of the material standard is checked for the entering 35CrMo steel bar and the matched material thereof; and appearance inspection and size inspection are carried out, and the surface has no obvious defects such as rust, pits and the like. The steel bar leaving the factory must have a shear resistance and tensile strength detection report, so that the use requirement is ensured to be met.

4. The specification, performance and quality of the steel pipe and the fastener meet the regulations of the current standard, and a delivery qualification certificate is required; the steel pipe is straight, the permissible deviation of the straightness is 1/500 of the pipe length, two end faces are smooth, inclined openings and burrs are avoided, and the steel pipe with hard injuries (hard bending, flat smashing and the like) and serious corrosion is forbidden to be used; the horizontal reinforcing rods, the floor sweeping rods, the cross braces and the like are welded steel pipes, and corrosion bending, deformation damage and cracks are avoided; and (3) establishing a steel pipe and fastener using machine accounts on a construction site, and recording the source, quantity, quality inspection and other conditions of the steel pipe and the fastener in detail.

5. Template and main arris, inferior arris: this engineering template all adopts waterproof bamboo plywood template, and bamboo plywood thickness specification is 15mm, and template time stupefied (roof beam) adopts the square timber of 10cm x 10cm specification, and main stupefied channel-section steel that adopts 5cm x 10cm specification, and the requirement of template and square timber, channel-section steel performance is as follows:

(1) the bamboo plywood formwork and the supporting system thereof are not wood with large brittleness and serious distortion and deformation;

(2) the template can ensure that the position, shape and size of an engineering structure and a member meet the design requirements;

(3) the concrete has enough bearing capacity, rigidity and stability, can reliably bear the weight and the lateral pressure of newly cast concrete, and various load combinations generated in the construction process, and does not deform, damage or collapse;

(4) the structure strives for simply, installs and removes the convenience, and the ligature and the installation of the reinforcing bar of being convenient for to satisfy the concrete and pour and the maintenance requirement.

The beneficial effects of the present embodiment are analyzed as follows:

(1) economic benefits are as follows:

according to the construction method, the side wall of the communication channel is constructed firstly, deformation of the post-wall pile body and the foundation pit is effectively inhibited, the construction risk of earthwork excavation near an island working surface is greatly reduced, the safety risk of earthwork excavation of the water collecting tank is effectively reduced, the construction measures such as dewatering or freezing methods and the like are not required to be adopted as in the construction of a sequential construction method, and the construction cost is effectively controlled.

(2) The construction period benefit is as follows:

after the construction of the side wall of the connection channel is completed, the construction of the interval main line structure and the entrance and exit field line structure is started, the construction time of the bottom plate and the water collecting tank of the connection channel structure is arranged on a non-critical line, and the insertion operation is performed with the track laying construction, so that the traditional construction treatment strengthening time of 20d and the earthwork excavation of 5d are saved, the operation surface can be provided for the track construction 30d in advance, and the completion of the construction task of the construction period of the subway is greatly ensured.

(3) Social benefits are as follows:

the construction joint waterproof construction and treatment method adopted by the construction method effectively ensures the construction quality of the outer waterproof layer and the waterproof construction quality of the construction joint structure, avoids the occurrence of quality hidden dangers such as structure leakage caused by insufficient treatment measures, effectively ensures the construction safety and the construction period node, has very important popularization value, and has good social benefits compared with the traditional sequential construction method.

The reverse construction method for the contact channel structure of the open cut section of the subway, disclosed by the invention, economically and effectively solves the contradictions of construction period, quality, safety and the like of the contact channel and the water collecting tank of the open cut section of the sand aquifer, and provides a good reference value for engineering construction.

The above-described embodiments are merely preferred embodiments of the present invention, and should not be construed as limiting the present invention, and features in the embodiments and examples in the present application may be arbitrarily combined with each other without conflict. The protection scope of the present invention is defined by the claims, and includes equivalents of technical features of the claims. I.e., equivalent alterations and modifications within the scope hereof, are also intended to be within the scope of the invention.

Claims

1. A reverse construction method for a contact channel structure of an open cut interval of a subway is characterized by comprising the following steps: it comprises the following steps:

s1, excavating a foundation pit, and constructing a front line bottom plate (9) in the small foundation pit after the excavation is finished; then constructing the main line side wall (3) and the connection channel side wall (7), and respectively arranging horizontal construction joints on the main line bottom plate (9) and the connection channel side wall (7);

s2, constructing an entrance and exit field line bottom plate (10) above the positive line side wall (3) and the communication channel side wall (7), and constructing an entrance and exit field line top plate (11) above the entrance and exit field line bottom plate (10);

s3, arranging a plurality of grouting floral tubes (30) at the periphery of a water collecting pool (8) area with a preset plan for grouting reinforcement; then, carrying out earth excavation on the water collecting tank (8), and then treating the construction joint; after excavation, constructing a bottom plate (13) and side walls (14) of the water collecting tank in sequence; constructing a connection channel bottom plate (15) after constructing the pool structure, and finally constructing a water collecting pool cover plate (12) and a fireproof door (16);

and S4, plugging the waterproof sleeve (31) reserved on the entrance field line bottom plate (10) and the entrance line top plate (11), and finishing construction.

2. The reverse construction method of the connection channel structure of the subway open cut region according to claim 1, characterized in that: in the step S1, before the construction of the main line bottom plate (9), the construction of the cushion layer, the waterproof layer and the protective layer of the main line bottom plate (9) is completed, and a horizontal construction joint is arranged at the joint of the main line bottom plate (9) and the communication channel bottom plate (15).

3. The reverse construction method of the connection channel structure of the subway open cut region according to claim 2, characterized in that: the specific construction steps of the horizontal construction joint are as follows:

A. positioning and paying off are carried out on the waterproof protection layer of the bottom plate, and a back-attached water stop belt (24) is installed;

B. mounting a construction joint lower-layer template (171), and sticking a sealing rubber strip (23) at the bottom of the construction joint lower-layer template (171); vertical battens (191) are tightly attached to the lower layer template (171), and then horizontal battens (192) are tightly attached to the vertical battens (191);

C. a water stop steel plate (25) is arranged at the bottom of the lower formwork (171) of the construction joint;

D. a construction joint upper-layer template (172) is installed on the water stop steel plate (25), and the construction method of the construction joint upper-layer template (172) is the same as that of the construction joint lower-layer template (171);

E. the positioning ribs (18) are vertically arranged along two sides of the template, and the positioning ribs (18) and the embedded steel bars (20) are welded for fixing the template and the water stop steel plate (25);

F. the outside of the template is provided with an inclined strut steel bar (21), and two ends of the inclined strut steel bar are respectively welded with the positioning bar (18) and the embedded steel bar (20), so that the template and the water stop steel plate (25) are prevented from moving.

4. The reverse construction method of the connection channel structure of the subway open cut region according to claim 1, characterized in that: in the step S1, before the construction of the front side wall (3), the dismantling of the third layer of steel support of the foundation pit and the waterproof construction of the side wall are completed; before the construction of the side wall (7) of the connection channel, a horizontal construction joint is arranged at the bottom of the side wall (7) of the connection channel.

5. The reverse construction method of the connection channel structure of the subway open cut region according to claim 4, characterized in that: the specific construction steps of the horizontal construction joint are as follows:

A. digging a groove (28) along the inner side of the communication channel side wall (7);

B. laying the waterproof coiled material (26) from the groove (28), and after laying is finished, placing a foam plate (27) in the groove (28) and clinging to the waterproof coiled material (26);

C. installing and fixing a back-attached water stop belt (24) on the surface of the foam plate (27), and filling the groove (28) with fine sand;

D. after measurement and positioning, the embedded steel bars (20) and the water stop steel plates (25) are inserted, and the cushion layer (20) is poured and fixed.

6. The reverse construction method of the connection channel structure of the subway open cut region according to claim 1, characterized in that: in the step S2, the waterproof sleeves (31) are embedded in the plates of the entrance and exit field line bottom plate (10) and the entrance and exit field line top plate (11) so as to facilitate the pumping and drainage during the later stage of concrete pouring and excavation.

7. The reverse construction method of the connection channel structure of the subway open cut region according to claim 1, characterized in that: in step S3, the concrete steps of grouting reinforcement are as follows:

A. according to the position required by the scheme, the grouting perforated pipe (30) is driven into the position of the injected layer at a certain angle along the periphery of the water collecting tank (8);

C. 7d, excavating the earth in the water collecting pool (8), digging an anchor rod along with the excavation, hanging a wire mesh, mixing with cement mortar, and plastering, wherein 0.5 percent of an accelerating agent is added into the mortar;

D. arranging drain holes at the position with larger water seepage, adopting a PVC pipeline to be arranged along the slope with 5 percent inclination, wrapping the exterior with permeable non-woven fabrics, and arranging a water collecting pit in the foundation pit for pumping and draining.

8. The reverse construction method of the connection channel structure of the subway open cut region according to claim 1, characterized in that: in the step S3, the construction joint treatment is performed after the first layer of earth excavation is completed, the construction joint is roughened by an air pick, the water-stopping steel plate (25) is brushed by a steel wire brush, and finally, the construction joint is washed clean by clean water.

9. The reverse construction method of the connection channel structure of the subway open cut region according to claim 1, characterized in that: in the step S4, high-grade fine aggregate concrete is filled in the waterproof casing, the upper end and the lower end are welded and sealed by galvanized steel plates, after the top is welded, mortar is used for leveling, waterproof paint is coated, and a waterproof protective layer is poured.