CN115749793A - A construction method for the connecting passage of a cascading tunnel - Google Patents

Abstract

The invention discloses a method for constructing a communication channel of a stacked tunnel, which belongs to the technical field of underground engineering construction and comprises the following steps: when a shield tunnel is advanced to the upper/lower communication channel to be built, correspondingly assembling lining ring segments; adopting vertical freezing on the ground + Reinforce the soil around the lower communication channel by the freezing method in the cave; excavate the lower communication channel in the lower tunnel, and construct the primary support structure and the secondary lining structure; freeze the soil around the upper communication channel, excavate the upper communication channel in the upper tunnel, and construct the primary support Structure and secondary lining structure; construct the internal structure, and thaw after the main structure reaches strength. This method can solve the problems of large disturbance and unstable excavation surface during the construction period of the cascading connection, which is beneficial to ensure the safety of the project.

Description

A construction method for the connecting passage of a cascading tunnel

technical field

The invention belongs to the technical field of underground engineering construction, and in particular relates to a construction method for a connecting channel of a cascading tunnel.

Background technique

The statements herein merely provide background information related to the present invention and do not necessarily constitute prior art.

With the development of the economy and the increase in the demand for transportation infrastructure, the construction of subway tunnels is developing rapidly, and the underground traffic network is becoming larger and larger. The construction of subway tunnels will inevitably have overlapping sections, and the communication channel is used as an emergency during the operation of the subway. An important part of the safety guarantee system (safety and emergency evacuation, drainage, fire prevention, etc.), is a major risk source in the process of subway construction. Especially for stacking tunnels, the overall volume of the connecting passage is large, the excavation period is long, the distance between the upper and lower horizontal passages is relatively close, the disturbance of the upper and lower passages to the soil is large and they affect each other, and when the connecting passage and the pump When the bottom of the building is located in clay or medium sandy soil (containing confined water), major engineering accidents such as vault collapse and face instability are prone to occur during construction.

Contents of the invention

Aiming at the deficiencies in the prior art, the purpose of the present invention is to provide a construction method for the cascading tunnel connection channel, which can solve the problems of large disturbance and unstable excavation surface during the construction period of the cascading tunnel, and is conducive to ensuring the safety of the project .

In order to achieve the above object, the present invention is achieved through the following technical solutions:

In a first aspect, the present invention provides a construction method for a cascading tunnel communication channel, comprising the following steps:

When the shield is advanced to the proposed upper/lower layer communication channel, the lining ring segment should be assembled correspondingly;

Use ground vertical freezing + in-hole freezing method to strengthen the soil around the lower communication channel;

Excavate the lower connecting channel for the lower tunnel, and construct the primary support structure and the secondary lining structure;

Freeze the soil around the upper communication passage, excavate the upper communication passage for the upper tunnel, and construct the primary support structure and the secondary lining structure;

The internal structure is constructed, and the main structure reaches its strength and then thawed out.

As a further technical solution, when the soil around the lower communication channel is reinforced, a circulating pipeline is drilled from the downline grouting port and the ground to freeze and reinforce the soil around the lower communication channel, and the reinforcement in the hole is frozen by means of reserved holes.

As a further technical solution, during reinforcement, multiple pressure relief holes are evenly distributed in the closed area of the tunnel freezing curtain, and pressure gauges are installed on the pressure relief holes to monitor the pressure changes in the freezing curtain in real time, judge the formation of the freezing curtain, and release frost heave pressure.

As a further technical solution, before freezing and strengthening, install temporary supports and bearing plates on the openings of the upper and lower tunnel lining rings.

As a further technical solution, the construction process of the lower tunnel is as follows:

After the reinforced soil meets the excavation requirements, the opening part of the lower tunnel lining ring segment is removed, and the upper cavern of the lower connecting passage is excavated from the lower tunnel by the step method, the initial support structure is constructed, the lower cavern is excavated, and the initial tunnel is constructed. For the support structure, after the initial support is closed, the waterproof layer and the second lining structure of the lower communication channel shall be constructed from bottom to top, and the steel bar joints connected with the second lining of the vertical section shall be reserved;

After the second lining of the lower communication channel reaches the design strength, remove the initial support at the pump room downwards and excavate the pump room. After the initial support of the pump room is closed, waterproof the pump room and the second lining from bottom to top, and waterproof the vertical section of the lower communication channel. , Side seam, reserve a steel bar connector connected to the upper side wall.

As a further technical solution, after the pump house and the second lining of the vertical section of the lower communication channel reach strength, part of the freezing pipes are reduced so that the top of the vertical section is in the frozen body, and the soil around the upper communication channel is frozen at the same time.

As a further technical solution, after the lining segment is assembled, the fresh air shaft steel pipe is drilled from the ground to the elevation of the roof bottom of the vertical passageway.

As a further technical solution, the construction process of the upper tunnel is as follows:

Excavate the upper cavern of the upper communication passage from the upper tunnel by step method, construct the primary support structure, excavate the lower chamber, and make the initial support. After the initial support is closed, construct the waterproof and secondary lining structure of the upper communication passage from bottom to top. Reserve the steel bar joints connected with the second lining of the vertical section; after the second lining of the upper communication channel reaches the design strength, remove the initial support downwards, excavate the remaining vertical section channels, and after the initial support of the vertical section channel is connected to both ends and closed, Waterproofing, side walls, and roof of the vertical section shall be constructed from bottom to top. The roof shall be connected to the steel pipe of the fresh air shaft, the steel bars of the roof shall be welded to the steel pipe of the fresh air shaft, the concrete shall be poured densely outside the connection, and a steel bar connector shall be reserved at the bottom of the side wall.

As a further technical solution, after the completion, the floor grille of the straight section will be removed, and the last part of the straight section will be excavated downwards for initial support. The second liner of the lower layer communication passage and the vertical section passage are connected as a whole.

As a further technical solution, when thawing is caused by thawing, use pre-embedded grouting pipes and segment grouting holes for thawing grouting filling, use single-liquid grouting, and use bottom-up, small and multiple grouting In the grouting method, after the deformation of the channel vault is stable, the melt-settling grouting is stopped, and after the grouting is completed, the holes are sealed with double-liquid grout.

The above-mentioned beneficial effects of the present invention are as follows:

The construction method of the present invention adopts vertical freezing on the ground and freezing in the cave to strengthen the surrounding soil of the upper and lower communication passages, which has good safety and can effectively isolate groundwater; it has a wide range of applications and is suitable for any loose rock and soil layer with a certain amount of water. The freezing technology is effective and feasible under the conditions of complex hydrogeology such as soft soil, water-containing unstable soil layer, quicksand, high water pressure and high ground pressure formation; it has good flexibility and can artificially control the shape and expansion range of the frozen body, and can be used when necessary Freezing bypasses underground obstacles; the controllability is good, and the frozen and reinforced soil is uniform and complete; it is economically reasonable.

The construction method of the present invention, due to the large volume of the connecting channel of the stacked tunnel and the long construction period, adopts the segmental freezing method of the upper and lower layer connecting channels, which can effectively reduce the disturbance of the upper and lower layer channel construction to the soil and reduce the risk of mutual interference .

The construction method of the present invention uses the step method to excavate the transverse passage, which can reduce the disturbance to the surrounding rock, and significantly reduce the risk of vault collapse and tunnel face instability during the construction process of the connecting passage in the cascading section.

According to the construction method of the present invention, the structure of the cascading tunnel communication channel formed can not only ensure that the communication channel meets the emergency evacuation requirements of personnel in disaster conditions, but also ensure that the pump room is set at the lowest point of the track in the main line section and the ballast bed will accumulate water. Drain normally to the interior of the pump room.

Description of drawings

The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention, and the schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations to the present invention.

Fig. 1 is the flow chart of the construction method of the cascading tunnel connecting passage of the present invention;

Fig. 2 is a schematic diagram of the positional relationship of lining ring segments in step 1 of the present invention;

Fig. 3 is a schematic diagram of the positional relationship between the ground, the fresh air well steel pipe, and the vertical section roof of the channel in step 2 of the present invention;

Fig. 4 is the construction schematic diagram of the temporary support and support plate in the lower and upper tunnel opening rings in step 3 of the present invention;

Fig. 5 is the construction schematic diagram of the frozen reinforcement of the soil around the lower communication channel in step 4 of the present invention;

Fig. 6-1 is the construction schematic diagram of adopting the step method to excavate the lower layer communication channel from the lower layer tunnel in step 5 of the present invention;

Fig. 6-2 is the construction schematic diagram of cross channel in step 5 and step 8 of the present invention;

Fig. 7 is the construction schematic diagram of pump house and the vertical section of lower passage in step 6 of the present invention;

Fig. 8 is the construction schematic diagram of frozen reinforcement of the soil around the upper layer communication channel in step 7 of the present invention;

Fig. 9 is a construction schematic diagram of excavating an upper-level connecting channel from the upper-level tunnel in step 8 of the present invention by adopting the step method;

Fig. 10 is the construction schematic diagram of remaining vertical section channel in step 9 of the present invention;

Fig. 11 is the construction schematic diagram of internal structures such as pressurized blower room, stair among 10 in the step of the present invention;

In the figure: The distance or size between each part is exaggerated to show the position of each part, and the schematic diagram is for illustration only;

Among them, 1-lining ring segment; 2-new air shaft steel pipe; 3-temporary support; 4-support plate; 5-soil around the lower communication channel; 6-lower tunnel; 7-lower communication channel; 8-upper cavern ;9-primary support structure; 10-lower cavern; 11-primary support; 12-waterproof layer; 13-second lining structure; 14-pump room; Upper communication channel; 18-vertical section channel; 19-pressurized blower room; 20-cover plate; 21-stairs.

Detailed ways

It should be noted that the following detailed description is exemplary and intended to provide further explanation of the present invention. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

In a typical implementation of the present invention, as shown in Figure 1, a construction method for a cascading tunnel connecting passage is proposed, comprising the following steps:

Step 1: When the shield is advanced to the proposed upper/lower communication channel, the lining segment 1 is assembled one by one. The side of the lining segment 1 has an opening, which can be disassembled, and is dug from the lining segment. The lower communication channel;

Step 2: Drill fresh air shaft steel pipe 2 from the ground to the elevation of the roof bottom of the vertical passage, and connect it to the roof of the vertical passage in the later stage; the fresh air shaft steel pipe is above the connecting passage and has a certain distance from the tunnel;

Step 3: Install temporary support 3, support plate 4, etc. in the openings of the lower and upper tunnel lining rings to control the deformation of the lining ring during construction;

Step 4: Use ground vertical freezing + in-hole freezing method for reinforcement, set up circulating pipelines from the downline grouting port and the ground to freeze and reinforce the soil 5 around the lower communication channel, and distribute them evenly in the closed area of the left and right freezing curtains Multiple pressure relief holes, install pressure gauges on the pressure relief holes, monitor the pressure changes in the freezing curtain in real time, judge the formation of the freezing curtain in time through daily observation, and directly release the frost heave pressure;

Step 5: After the reinforced soil meets the excavation requirements, remove the opening part of the lower tunnel lining ring segment, excavate the lower connecting channel 7 and the upper chamber 8 from the lower tunnel 6 using the step method, construct the initial support structure 9, and excavate In the lower cavern 10, the initial support structure 11 is constructed. After the initial support is closed, the waterproof layer 12 and the second lining structure 13 of the lower communication channel are constructed from bottom to top, and the steel bar joints connected with the second lining of the vertical channel 18 are reserved;

Step 6: After the second lining of the lower communication channel reaches the design strength, remove the 14 primary supports of the pump room downwards, excavate the pump room, and after the initial support of the pump room is closed, construct the waterproofing and second lining of the pump room from bottom to top, and the lower communication channel vertically Straight section waterproofing, side seam, rebar connector connected with the upper side wall is reserved;

Step 7: After the second lining of the vertical section of the pump room and the lower communication channel has reached its strength, reduce part of the frozen pipes, but the vertical section is only closed by the primary branch, and it is still necessary to ensure that the top of the vertical section is in the frozen body, and at the same time freeze the upper communication The soil body 15 around the channel adopts the same method as the freezing of the soil around the lower communication channel;

Step 8: After the reinforced soil meets the excavation requirements, excavate the upper cavern of the upper communication channel 17 from the upper tunnel 16 using the step method, construct the initial support structure, excavate the lower cavern, apply the initial support, and after the initial support is closed , from the bottom up to construct the waterproof and secondary lining structure of the upper communication channel, and reserve the steel bar joints connected with the secondary lining of the channel 18 in the vertical section;

Step 9: After the second lining of the upper communication channel reaches the design strength, the initial support can be removed downwards, and the remaining vertical section channel 18 is excavated. After the initial support of the vertical section channel is connected and closed with both ends, the vertical section is constructed from bottom to top Waterproofing of the channel, side walls, roof, the roof is connected to the steel pipe of the new air shaft, the steel bars of the roof are welded to the steel pipe of the new air shaft, the concrete outside the connection is poured densely, and the steel bar connector is reserved at the bottom of the side wall. After the completion, remove the floor grille of the straight section, excavate the last part of the straight section downwards, and apply initial support. The two linings of the straight channel are connected as a whole;

Step 10, construct internal structures such as pressurized blower room 19, cover plate 20, stairs 21, handrails, etc., and gradually defreeze after the main structure reaches strength.

Temporary support 3 and support plate 4 need to be removed after the construction is completed, and must be guided by the results of tunnel monitoring and measurement, that is, they can be removed only after the stress state of the overall structure of the tunnel and connecting passage tends to be stable.

Wherein, step 3 kinds of lining rings are 6 rings respectively for the left line and the right line.

Among them, in step 4, the reinforcement in the hole is frozen by means of reserved holes, which can facilitate the reinforcement of the interlayer soil and ensure the reinforcement range and safety. The effective freezing thickness of the frozen soil curtain outside the initial support is less than 3m, and it should also be properly carried out within the excavation range. Freeze reinforcement to ensure the stability of the excavation surface. The design value of the compressive strength of frozen soil is not less than 4Mpa, the design value of the flexural strength is not less than 1.8Mpa, and the design value of the shear strength is not less than 1.5Mpa.

无缝钢管；管前端开口进入土体段钻孔呈梅花状，以确保冻结帷幕内的压力有效传递。In step 4, the pressure relief pipe is selected

Seamless steel pipe; the opening of the front end of the pipe enters the soil section and the drilling is in the shape of a plum blossom to ensure the effective transmission of pressure in the freezing curtain.

Among them, in step 5 and step 8, after the reinforced soil meets the excavation requirements, the connecting channel is excavated by the step method, and the core soil is reserved by circular excavation for the step excavation on the channel. The actual situation is adjusted, and the excavation cycle footage of the channel is 0.5m.

Among them, in step 10, when thawing, during the natural thawing and settlement process of the permafrost layer, due to the increase of soil porosity and water content, the physical and mechanical parameters and deformation parameters become worse, and the structure and formation are prone to excessive deformation. Forced melt-settling grouting measures can be adopted to control structural and stratum deformation and reduce adverse effects on the surrounding environment and shield sections on both sides.

的焊接管，顶端接带螺纹的管箍，并用丝堵封闭。当停止地层冻结时将引起融沉，就可利用预埋注浆管及管片注浆孔等进行注浆填充。在隧道底部和喇叭口处可利用管片注浆孔，必要时再利用钻机开孔布设注浆孔，进行注浆。When melting and settling, the grouting pipe is selected

The welded pipe is connected with a threaded pipe collar at the top and closed with a plug. When the freezing of the ground will cause thawing, the pre-embedded grouting pipe and segment grouting holes can be used for grouting filling. Segment grouting holes can be used at the bottom of the tunnel and at the bell mouth, and if necessary, the drilling rig can be used to lay out the grouting holes for grouting.

The specific measures for melt-settling grouting are as follows:

(1) Slurry material and parameters. The grout is single liquid grout, and the ratio of cement grout should be water:cement = 1:1, the grouting amount for a single hole is 1m ³ , and the grouting pressure should not exceed 2 times the hydrostatic pressure.

(2) Grouting hole setting. Utilize the pre-buried grouting holes during structure construction, punch holes with a percussion drill, and drill holes with a hole drilling machine if necessary, and drill through the frozen wall for grouting.

(3) Grouting method. The method of grouting from bottom to top, small amount and multiple times is adopted, and the specific method is: grouting from the bottom plate of the channel, side walls and vault. After grouting, seal the holes with double-fluid grout.

(4) Monitoring of grouting construction process. The purpose of grouting is to control the settlement and deformation of the arch of the channel. Therefore, during the natural thawing process, it is necessary to strengthen the monitoring of the deformation of the vault of the channel. The monitoring data is the basis for adjusting the grouting parameters.

(5) The sign of the end of melting and sinking grouting. The end of the melt-settling grouting is based on the stable deformation of the channel vault. If the frozen wall is completely melted and the settlement of the channel vault lasts for one month, and the settlement of the channel vault is not greater than 0.5mm every half month, the melt-settling grouting can be stopped.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. A method of construction of a cascading tunnel connecting passage, is characterized in that, comprises the following steps: When the shield is advanced to the proposed upper/lower layer communication channel, the lining ring segment should be assembled correspondingly; Use ground vertical freezing + in-hole freezing method to strengthen the soil around the lower communication channel; Excavate the lower connecting channel for the lower tunnel, and construct the primary support structure and the secondary lining structure; Freeze the soil around the upper communication passage, excavate the upper communication passage for the upper tunnel, and construct the primary support structure and the secondary lining structure; The internal structure is constructed, and the main structure reaches its strength and then thawed out. 2. The construction method of the cascading tunnel communication channel as claimed in claim 1, characterized in that, when the soil around the lower layer communication channel is reinforced, a circulating pipeline is set up from the downline grouting port and the ground to freeze and reinforce the soil around the lower layer communication channel Body, the reinforcement in the hole is frozen by means of reserved holes. 3. The construction method of the cascading tunnel communication channel as claimed in claim 2, wherein during reinforcement, a plurality of pressure relief holes are evenly distributed in the closed area of the tunnel freezing curtain, and pressure gauges are installed on the pressure relief holes for real-time monitoring. Freeze the pressure changes in the curtain, judge the formation of the freeze curtain, and release the frost heave pressure. 4. The construction method of the connecting channel of the cascading tunnel according to claim 1, characterized in that, before freezing and strengthening, temporary supports and support plates are installed on the openings of the upper and lower tunnel lining rings. 5. The construction method of the cascading tunnel connecting passage as claimed in claim 1, wherein the construction process of the lower tunnel is: After the reinforced soil meets the excavation requirements, the opening part of the lower tunnel lining ring segment is removed, and the upper cavern of the lower connecting passage is excavated from the lower tunnel by the step method, the initial support structure is constructed, the lower cavern is excavated, and the initial tunnel is constructed. For the support structure, after the initial support is closed, the waterproof layer and the second lining structure of the lower communication channel shall be constructed from bottom to top, and the steel bar joints connected with the second lining of the vertical section shall be reserved; After the second lining of the lower communication channel reaches the design strength, remove the initial support at the pump room downwards and excavate the pump room. After the initial support of the pump room is closed, waterproof the pump room and the second lining from bottom to top, and waterproof the vertical section of the lower communication channel. , Side seam, reserve a steel bar connector connected to the upper side wall. 6. The construction method of the cascading tunnel communication channel as claimed in claim 5, characterized in that, after the pump room and the second lining of the vertical section of the lower communication channel reach the strength, part of the frozen pipes are reduced so that the top of the vertical section is in the frozen body , and freeze the soil around the upper communication channel at the same time. 7. The construction method of the connecting channel of the cascading tunnel according to claim 1, characterized in that, after assembling the lining ring segment, the fresh air shaft steel pipe is drilled from the ground to the elevation of the roof bottom of the vertical section channel. 8. The construction method of the cascading tunnel connecting passage as claimed in claim 7, wherein the construction process of the upper tunnel is: Excavate the upper cavern of the upper communication passage from the upper tunnel by step method, construct the primary support structure, excavate the lower cavern, and make the initial support. After the initial support is closed, construct the waterproof and secondary lining structure of the upper communication passage from bottom to top. Reserve the steel bar joints connected with the second lining of the vertical section; after the second lining of the upper communication channel reaches the design strength, remove the initial support downwards, excavate the remaining vertical section channels, and after the initial support of the vertical section channel is connected to both ends and closed, Waterproofing, side walls, and roof of the vertical section shall be constructed from bottom to top. The roof shall be connected to the steel pipe of the fresh air shaft, the steel bars of the roof shall be welded to the steel pipe of the fresh air shaft, the concrete shall be poured densely outside the connection, and a steel bar connector shall be reserved at the bottom of the side wall. 9. The construction method for the connecting channel of the cascading tunnel as claimed in claim 8, characterized in that, after the completion, the floor grid of the straight section is removed, the last part of the straight section is excavated downwards, initial support is applied, and all of them are dug through. Finally, waterproofing and side walls are constructed from bottom to top, so that the upper layer communication channel, the lower layer communication channel, and the second lining of the vertical section channel are connected as a whole. 10. The construction method of the cascading tunnel communication channel as claimed in claim 1, characterized in that, when thawing causes thawing, pre-embedded grouting pipes and segment grouting holes are used for thawing and grouting filling, and a single Slurry grouting adopts the grouting method from bottom to top, small amount and multiple times. After the deformation of the channel vault is stable, stop the melt-settling grouting. After the grouting is completed, use double-slurry grout to seal the hole.

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