CN112228091A

CN112228091A - Bottom sealing method for mechanical construction vertical shaft in tunnel

Info

Publication number: CN112228091A
Application number: CN202011461230.XA
Authority: CN
Inventors: 杨志强; 帅玉兵; 王利民; 吴昊; 李家帅; 马永生; 尹伟; 吴学勇
Original assignee: BCEG Civil Engineering Co Ltd
Current assignee: BCEG Civil Engineering Co Ltd
Priority date: 2020-12-14
Filing date: 2020-12-14
Publication date: 2021-01-15
Anticipated expiration: 2040-12-14
Also published as: CN112228091B

Abstract

The invention discloses a shaft bottom sealing method for mechanized construction in a tunnel, and belongs to the technical field of shaft bottom sealing construction of tunnels. After a pipe jacking machine in the vertical shaft tunnels to a set depth, concrete is poured in front of a cutter head through a concrete guide pipe preset by a cutter head central shaft on the pipe jacking machine, the concrete is poured while the cutter head is rotated and withdrawn forwards, the withdrawal speed of the cutter head is matched with the amount of the poured concrete, and underground water is guaranteed to flow into a mud sump of the pipe jacking machine without damaging a mud film; the mechanical construction method for the vertical shaft can effectively save underground resources, complete construction in a narrow working space, and reduce the number of the contact channels by setting the contact channels at the maximum interval according to the standard requirement without considering the lowest point of the longitudinal slope of the tunnel. In addition, the bottom sealing method can solve the problems of large water pressure and difficult bottom sealing of deep underground water, and provides guarantee for the construction of a built-in pump house.

Description

Bottom sealing method for mechanical construction vertical shaft in tunnel

Technical Field

The invention relates to a shaft bottom sealing method for mechanized construction in a tunnel, and belongs to the technical field of shaft bottom sealing construction of tunnels.

Background

After the contact channel is constructed by the mechanical method, the waste water pump house is planned to be constructed continuously by the mechanical method. Because the internal diameter of the connection channel is smaller, the internal diameter clearance is within 3 meters, if a mechanical construction pump house is adopted in the connection channel, the excavation diameter of the pump house is difficult to achieve more than 2 meters, the thickness of the lining is considered, the internal diameter clearance is smaller than 1.5 meters, the water storage capacity required by the specification is required to be achieved, the deep excavation is necessary, the occupied underground space resources are more, the water pressure is larger after the bottom excavation is completed, and the bottom sealing is difficult. Even if the underground space allows, the bottom sealing can be realized, but the working pump house is implemented downwards by a mechanical method in a clearance tunnel with the diameter of 3 meters, and the working space is basically not available, so that the method is not practical.

The existing mechanical method vertical shaft bottom sealing method is divided into a permanent bottom sealing method and a temporary bottom sealing method.

(1) The shaft is permanently bottomed. And after the excavation is in place, sealing the bottom by a method of spraying concrete from four sides to the middle in a layering manner.

(2) And temporarily sealing the bottom of the vertical shaft. And when the vertical shaft is excavated and supported to a certain elevation below each layer of the temporary inverted arch of the transverse passage, performing temporary bottom sealing on the vertical shaft, wherein the bottom sealing method is the same as the permanent bottom sealing of the vertical shaft. And after the bottom sealing concrete reaches the strength, breaking the ingate of the transverse passage into the hole. And when the upper-layer pilot tunnel enters the tunnel for a certain depth, breaking the temporary bottom seal of the vertical shaft, and continuously excavating the vertical shaft. Circulating like this, breaking the horse head door of every layer of horizontal passageway and going into the hole, and every layer of horizontal passageway all will stagger certain safe distance, carries out the permanent back cover of shaft at last. During construction, attention needs to be paid to control the cross operation risk during vertical shaft construction and transverse channel construction.

The design of the built-in pump room realizes the separation arrangement of the pump room and the connection channel, so that the plane position of the connection channel does not need to be considered and is combined with the pump room, the design of the interval longitudinal section is more flexible, the optimization space of the interval line longitudinal section design scheme is enlarged, and convenience is provided for the comprehensive practice of the non-mine method connection channel construction technology. The invention creates convenient conditions and provides technical guarantee for the construction of the built-in pump house.

The existing built-in pump house has the following defects that firstly, under the action of a plurality of factors such as long-term frequent water level change, alternation of wetting and drying, dynamic load of train circulation, electrochemical corrosion and the like, the possibility of finally causing damage due to cracking, segregation, scouring and loss of track bed concrete exists; secondly, the resources under the occupied land are more, the deep groundwater pressure is high, and the bottom sealing is difficult. How to improve the performance of the water pump and the bottom sealing concrete is the key for solving the problems.

Disclosure of Invention

The invention aims at the technical problems of large pump house burial depth, high underground water level, large water pressure and limited operation space, thereby designing the mechanical construction shaft back cover.

The technical scheme adopted by the invention is a shaft bottom sealing method for mechanized construction in a tunnel, pipe jacking equipment and a matched trolley are transported to a shaft construction position, the initial position is adjusted, and a pipe piece supporting system is adjusted to a working position. And (4) removing the bottom guide rail, and lowering the recyclable pipe jacking host machine to a position contacting with the pipe piece by the crane. And welding the starting steel sleeve, filling grease between the shield tail brushes, and preparing before starting. Cutting a special steel-concrete composite pipe piece in the main tunnel, transporting the pipe-jacking pipe piece to a specified position, preparing to start tunneling, and deslagging in a slurry mode until jacking to a designed depth.

And further, jacking the pipe jacking machine downwards in place in the shield tunnel, replacing mud water in the mud water bin by using shield mud and compressing the mud water to form a mud film, unbinding the shell of the pipe jacking machine and the cutterhead compartment plate, and preparing to start the retraction of the cutterhead and pouring concrete.

Furthermore, concrete is poured in the front of the cutter head through a concrete pipe preset in the center shaft of the cutter head, the concrete is poured while the cutter head is rotated, the retracting speed of the cutter head is matched with the amount of the poured concrete, and underground water is guaranteed not to damage a mud film and to rush into a mud sump of the pipe jacking machine.

Furthermore, after the concrete is solidified, the cutter head is removed, and the concrete, the pipe jacking machine shell, the pipe jacking pipeline and the shield tunnel form a watertight whole together to resist underground water together.

The invention constructs the vertical shaft by a mechanical method, unbinds the position relation of the connection channel and the pump room, directly constructs the pump room in the shield main tunnel, and solves a series of construction problems caused by the fact that the diameter of the pump room is difficult to reach more than two meters, the operation space is narrow and the depth of the pump room is greatly increased in the process of continuously constructing the pump room in the connection channel. Underground resources can be effectively saved, construction is completed in a narrow working space, the lowest point of the longitudinal slope of the tunnel is not needed to be considered in the contact channel, the maximum distance can be set according to the standard requirement, and the number of the contact channels is reduced. In addition, the bottom sealing method can solve the problems of large water pressure and difficult bottom sealing of deep underground water, and provides guarantee for the construction of a built-in pump house.

Drawings

FIG. 1 is a schematic view of a push bench head being pushed down.

FIG. 2 is a schematic diagram of the head partition plate and the shield body of the push bench.

Fig. 3 is a schematic structural view of the poured concrete.

Fig. 4a is a schematic diagram of concrete pouring of a concrete guide pipe to the front of the cutterhead, and fig. 4b is a schematic diagram of secondary lining.

FIG. 5 is a flow chart of a mechanical construction process.

Detailed Description

The present invention will be described in detail below with reference to the accompanying drawings and examples.

The structure of the mechanical construction shaft bottom sealing in the tunnel comprises a shield body, a folding cutter head, a hydraulic oil cylinder, a lengthened seal and the like. The hydraulic oil cylinder is connected with the shield body and the folding cutter head through a support on the flange plate and is fixedly connected through a pin shaft. The lengthened seal is installed on the flange surface at the top of the shield body in the pipe jacking machine and is connected with the shield body through bolts. After a pipe jacking machine in the shaft is tunneled to a set depth, concrete is poured in front of a cutter head through a concrete guide pipe preset by a cutter head central shaft on the pipe jacking machine, the concrete is poured while the cutter head is rotated and withdrawn forwards, the withdrawal speed of the cutter head is matched with the amount of the poured concrete, and underground water is guaranteed to be flushed into a mud sump of the pipe jacking machine without damaging a mud film (as shown in figure 4 a); and after the concrete is solidified, removing the cutter head, applying second lining concrete in the pipe-jacking pipeline (as shown in figure 4 b), and finishing the bottom sealing of the water storage space of the pump house.

The method mainly comprises four steps, specifically as follows:

s1, after the head of the push bench is pushed downwards to the proper position, the mud water in the mud water bin is replaced by shield mud and compressed to form a mud film, as shown in figure 1.

S2, maintaining pressure, removing the mud inlet and outlet pipeline, connecting a concrete pump inlet pipeline through a central pump pipe connector, and unbinding the partition plate of the head of the pipe jacking machine from the shield body, as shown in figure 2.

S3, starting the drive, and starting to contract the hydraulic oil cylinder to lift the folding cutter head, wherein the cutter head rotates and retracts under the combined action of the drive and the oil cylinder. In the lifting process, the stroke difference between the oil cylinders is controlled to be not more than 10mm so as to achieve the effect of synchronous lifting. And in the process of retracting the cutter head, concrete is injected into the pump pit through the interface of the central pump pipe. The retreating speed of the main engine and the injection amount of the concrete are strictly controlled to be balanced in the process, the compressed air injection is not stopped in the whole process, the pressure of the soil bin is kept unchanged, the pressure is withdrawn by about 1000 mm-1500 mm, and the concrete with the thickness of 1000 mm-1500 mm is poured, as shown in figure 3.

And S4, after the pouring is finished, the cutter head is not lifted any more, after the pressure is maintained until the concrete has certain strength, the cutter head is continuously lifted, the hydraulic oil cylinder, the folding cutter head and the inner shield are lifted and sealed in an lengthening way together, the cutter head is separated from the outer shield, and the cutter head is completely retracted. And (5) concrete is solidified and formed, and bottom sealing is completed. The cutter head always keeps rotating at a low speed (0.1-0.3 rpm) in the whole bottom sealing process until the concrete is initially set.

The core of the invention mainly comprises the following points:

1. the concrete pouring speed is matched with the cutter disc retraction speed, and the excavation surface pressure drop is within an allowable range. The pressure of the excavation surface is kept, so that the concrete can be smoothly formed and is not jacked up by the water and soil pressure possibly existing at the bottom, the concrete can be more closely fit with the shape of the excavation surface, and the good bottom sealing effect is ensured;

2. the effect of pouring concrete is ensured to be complete, the effect of water and soil pressure at the bottom of the pump house can be resisted, and the waterproof requirement is met. Poor grouting effect can cause cracks in formed concrete, and after bottom sealing is finished, the water and soil pressure subsided by excavation can rise again, so that weak parts existing in the cracks can be damaged, and bottom sealing failure can be caused. Therefore, the perfect grouting effect is also an important part in the method.

As shown in fig. 5, a flow chart of a mechanical construction process mainly includes the following steps: a. the pipe jacking equipment and the matched trolley are transported in place, and the pipe piece supporting system is adjusted to a working position; b. removing the bottom guide rail, and lowering the recoverable pipe jacking host machine to a position contacting with the pipe piece by the crane; c. welding an initial steel sleeve, and filling grease between shield tail brushes; d. cutting special steel-concrete pipe pieces in the main tunnel, and conveying the pipe pieces to a designated position; e. starting tunneling, and deslagging by adopting a muddy water mode until the tunneling reaches the designed depth; f. injecting shield mud into the mud bin to replace mud water in the mud water bin, and pumping compressed air into the mud bin to form a mud film protecting wall; g. unbinding the pipe jacking machine shell and the cutter head partition plate; h. removing the flange, withdrawing the main machine, utilizing a central shaft of the cutter head to preset a concrete pipe while withdrawing, and injecting the concrete into the concrete back cover, wherein the withdrawal speed of the main machine is matched with the speed of pouring concrete; i. and solidifying the concrete, dismantling the cutter head, applying a second lining and finishing bottom sealing.

The invention has the innovation point that grouting and bottom sealing can be carried out while the cutter head is recovered, thereby not only ensuring the safety of the project, but also shortening the construction period and having research significance. In addition, the bottom sealing method can solve the problems of large water pressure and difficult bottom sealing of deep underground water, and provides guarantee for the construction of a built-in pump house. To ensure the smooth implementation of the key process of backing concrete and sealing concrete bottom under the water pressure of 0.3MPa, the initial setting time of concrete is paid attention.

Claims

1. A bottom sealing method for a vertical shaft in mechanical construction in a tunnel is characterized by comprising the following steps: transporting the pipe jacking equipment and the matched trolley to a vertical shaft construction position, adjusting the initial position, and adjusting the pipe piece supporting system to a working position; removing the bottom guide rail, and lowering the recoverable pipe jacking host machine to a position contacting with the pipe piece by the crane; welding an originating steel sleeve, filling grease between shield tail brushes, and preparing before originating; cutting a special steel-concrete composite pipe piece in the main tunnel, transporting the pipe-jacking pipe piece to a specified position, preparing to start tunneling, and deslagging in a slurry mode until jacking to a designed depth.

2. The method for mechanically constructing the shaft bottom cover in the tunnel according to claim 1, wherein the method comprises the following steps: and (3) jacking the pipe jacking machine in the shield tunnel to a proper position downwards, replacing mud water in the mud water bin by using shield mud and compressing the mud water to form a mud film, unbinding the shell of the pipe jacking machine and the cutter compartment plate, and preparing to begin to withdraw the cutter and pour concrete.

3. The method for mechanically constructing the shaft bottom cover in the tunnel according to claim 2, wherein the method comprises the following steps: concrete is poured into the front of the cutter head through a concrete pipe preset in the center shaft of the cutter head, the concrete is poured while the cutter head is rotated, the cutter head is withdrawn forwards, the withdrawal speed of the cutter head is matched with the amount of the poured concrete, and underground water is guaranteed to be prevented from damaging a mud film and gushes into a mud sump of the pipe jacking machine.

4. The method for mechanically constructing the shaft bottom cover in the tunnel according to claim 3, wherein the method comprises the following steps: and after the concrete is solidified, the cutter head is removed, and the concrete, the pipe jacking machine shell, the pipe jacking pipeline and the shield tunnel form a watertight whole together to resist underground water together.