CN113756825A

CN113756825A - Mechanical method connecting channel construction method utilizing pipe jacking technology

Info

Publication number: CN113756825A
Application number: CN202111018962.6A
Authority: CN
Inventors: 葛佳佳; 李海波; 赵星星; 刘阳; 杨敏龙; 徐汪豪; 周长永; 刘晓波; 张永南; 张想陈
Original assignee: Zhejiang Hanghai Intercity Railway Co ltd; China Tiesiju Civil Engineering Group Co Ltd CTCE Group; Second Engineering Co Ltd of CTCE Group
Current assignee: Zhejiang Hanghai Intercity Railway Co ltd; China Tiesiju Civil Engineering Group Co Ltd CTCE Group; Second Engineering Co Ltd of CTCE Group
Priority date: 2021-09-01
Filing date: 2021-09-01
Publication date: 2021-12-07

Abstract

The invention relates to a mechanical method connecting channel construction method by using a pipe jacking technology, which comprises the following steps: s1, construction preparation; s2, starting a jacking pipe and performing tunneling construction; and S3, receiving construction by the jacking pipe. The invention has the beneficial effects that: the assembled connection channel structure and the pipe jacking method construction method have the advantages of high construction mechanization degree, reliable quality, high speed, no need of soil body pre-reinforcement, low manufacturing cost, small environmental disturbance and the like; the small-diameter earth pressure balance push bench and the rear supporting equipment adopted by the invention are integrally designed with the tunnel inner support system, so that tunneling, segment assembling, slag discharging, feeding and grouting in the tunnel construction process are realized, and full-mechanized operation is realized. The inner support system is provided with an oil pressure automatic regulating device, so that the jacking force of the support oil cylinder can be automatically regulated along with the stress change of the tunnel, and the automatic service can be comprehensively realized.

Description

Mechanical method connecting channel construction method utilizing pipe jacking technology

Technical Field

The invention relates to the technical field of subway communication channel construction, in particular to a mechanical method communication channel construction method utilizing a pipe jacking technology.

Background

In the middle of the urban rail transit up-down tunnel, a channel is excavated, and a structure or a structure of a partition wall and a fireproof door is arranged in the channel and is called as a communication channel. If the contact channel is located the tunnel interval lower extreme, can reduce the contact channel elevation, excavate the sump pit downwards in contact channel bottom simultaneously, communicate interval tunnel water diversion system that looses, install drainage facilities such as water pump simultaneously. The communication channel is mainly used for communicating the subway up-down tunnel, people can be evacuated in emergency, the communication channel can also be used as a life channel for emergency rescue, and water collection and drainage of the tunnel are considered.

At present, tunnel construction technologies such as mining method excavation and the like are mostly adopted for urban rail communication channels, grouting or freezing reinforcement is assisted to ensure stability of surrounding rocks during tunnel excavation, but the construction method has natural defects in the aspects of reinforcement construction or excavation construction and the like, the conventional freezing method has the problems of long construction period, high construction cost, potential quality hazard and the like, but the method cannot be applied to strata with low water content, if liquid nitrogen is used for freezing, the construction cost is higher, and the conventional grouting reinforcement has the problems of ground space occupation, potential safety hazard, long construction period, potential quality hazard and the like. The urban rail transit construction is mostly under a main road, the traffic flow is large, the space condition is lacked, the mine method construction mainly utilizes the natural or reinforced soil body self-stability to ensure the excavation safety, the technological requirement is high, the construction process management requirement is high, the emergency guarantee measures are complex, and the accidents such as collapse and the like, such as the accident of water seepage and sand running of No. 4 line of Shanghai subway, and the like easily occur.

In recent years, the adoption of a mechanical method for excavating an interconnection channel has been developed and primarily applied to various major cities in China, for example, the Chinese patent with the application number of CN201910655321.8 discloses an interconnection channel construction method by means of tunnel shield construction. Chinese patent application No. CN201710216575.0 discloses an assembled connection channel structure and a construction method thereof, which adopts a shield method propulsion mode, and the method is suitable for connection channel construction at a longer distance, but the method cannot carry out synchronous grouting, is suitable for a weak water-bearing stratum, and has a certain risk for a water-bearing stratum. Chinese patent with application number CN201810537259.8 discloses a tunnel shield construction method and a tunnel, which gradually assembles and lengthens the shield shell and finally retains the shield shell in the soil body during the shield construction process, and the tunnel shield construction method and the tunnel shield are high in cost and difficult to popularize comprehensively.

Disclosure of Invention

The invention aims to overcome the defects in the prior art, provides a mechanical method connecting channel construction method by using a pipe jacking technology, is used for solving or partially solving the technical problem of construction of a connecting channel between an uplink tunnel and a downlink tunnel of urban rail transit, ensures the safety of constructors and reduces the construction cost.

The mechanical method connecting channel construction method utilizing the pipe jacking technology comprises the following steps:

s1, construction preparation;

s1-1, arranging in the main tunnel;

s1-2, main tunnel grouting reinforcement: lining the whole ring at the starting end position and the receiving end position of the communication channel and the position of the communication channel for grouting reinforcement, wherein the grouting adopts cement paste and water glass solution;

s1-3, manufacturing an initial tunnel portal ring beam;

s1-4, positioning equipment and connecting a sleeve;

s1-5, starting sleeve and receiving sleeve filling;

s2, starting a jacking pipe and performing tunneling construction;

s2-1, control of originating parameters: after the pipe jacking machine is sealed by the sleeve, cutting tunnel portal concrete for starting, and determining soil bin pressure, thrust, torque, propelling speed, cutter head rotating speed, grouting amount, screw machine gate opening, grease injection and soil discharge amount in the starting process;

s2-2, tunneling parameter control: in the normal tunneling section, the propulsion speed of the pipe jacking machine is controlled to be 20-30 mm/min, and other tunneling parameters are kept unchanged;

s2-3, assembling pipe joints: the whole ring of the communication channel is divided into two standard blocks, and the standard blocks are assembled in a staggered joint mode without wedge-shaped amount; the pipe joints are placed on a pipe joint transportation platform according to the installation sequence through a crane, after the tunneling is finished, the pipe joints are sent to a pipe joint installation range through a pipe joint hoisting device to be installed, the pipe joints are tightly propped by a propulsion oil cylinder which stretches out of a corresponding position after the pipe joints are installed in place, when the jacking force of the propulsion oil cylinder is larger than the force required for stabilizing the pipe joints, a pipe joint installing machine is removed, the ovality of a lining ring is measured, and longitudinal bolts are screwed down;

s2-4, antifriction grouting: thixotropic slurry is adopted for antifriction grouting in the tunneling process, and soil body gaps on the outer wall of the pipe are filled;

s2-5, grouting behind the wall: after the push-in of the push bench is finished, replacing a slurry sleeve by using hard slurry, and plugging a grouting hole, wherein the hard slurry is double-liquid slurry of cement slurry and water glass solution, and the grouting pressure is controlled within 0.5 MPa;

s2-6, attitude control: the maximum deviation amount of jacking of the push bench is not more than +/-50 mm, and if deviation occurs in the jacking process when the posture is met, the posture of the push bench is adjusted by adjusting the pressure distribution of a jacking oil cylinder;

s3, receiving construction by a jacking pipe;

s3-1, receiving construction preparation: before receiving, accurately measuring the position of the pipe jacking machine, determining the relation between the central axis of the tunnel to be tunneled and the central axis of the tunnel design, simultaneously rechecking and measuring a steel pipe sheet at the position of the receiving tunnel door, and determining the through posture of the pipe jacking machine and a tunneling deviation rectifying plan;

s3-2, receiving the construction of the portal ring beam;

s3-3, mounting of a receiving sleeve: the receiving steel sleeve is divided into four sections, wherein the front end, the lengthening ring and the rear end are integrated rings, and the middle section is divided into an upper semicircle and a lower semicircle; the receiving sleeve is welded at the steel-concrete composite pipe piece with the opening; conveying the steel-concrete composite pipe piece into a tunnel by using a No. 5 rear matching trolley, adjusting the posture of a receiving sleeve by using a jack and a chain block, and welding the front end of the sleeve and a reserved hole door on the steel-concrete composite pipe piece into a whole from the interior of the sleeve; after the sleeve is connected in place and the supporting system is loaded, the sleeve is reinforced at the outer ring, I-shaped steel is adopted for supporting along the axial direction and the annular direction of the sleeve for reinforcement, one end of the support is welded on the outer arc of the sleeve, and the other end of the support is supported on the duct piece;

s3-4, sleeve joint sealing treatment: welding is adopted between the receiving sleeve and the main tunnel steel pipe sheet and three circumferential seams and two longitudinal seams of the steel sleeve, after welding is completed, the welding seam sealing water is detected, the welding seam quality is checked, and repair welding treatment is carried out if quality defects occur; a steel sleeve longitudinal stiffening plate is added at the position of the steel pipe sheet partition plate;

s3-5, steel sleeve filling: when the cutter head is close to the segment at the receiving end, the tunneling is stopped, after the steel sleeve is assembled, the steel sleeve is filled, the filling material is mortar, the mortar is pumped into the steel sleeve by using a squeeze pump until the steel sleeve is completely filled, and a sealing test is carried out;

and S3-6, the pipe jacking machine reaches tunneling.

Preferably, step S1-1 includes the steps of:

s1-1-1, laying a track: after the construction of the main tunnel is finished, paving a track according to the track gauge of the pipe jacking machine trolley; if the track gauge of the trolley is the same as that of the main tunnel battery car, reinforcing the track; after the tracks are laid, a track board is arranged in the middle of the double tracks and is fixed by iron wires;

s1-1-2, hydroelectric installation: arranging a water supply pipe and a water drainage pipe in the main tunnel, wherein the water supply pipe and the water drainage pipe are made of galvanized steel pipes; two circuits are distributed in the tunnel at the originating side, one circuit in the circuits is a high-voltage cable, the other circuit is a lighting circuit, and the lighting circuit adopts an LED lamp strip; and one path of low-voltage power cable is arranged in the receiving side tunnel.

Preferably, step S1-3 includes the steps of:

s1-3-1, measuring a release point and positioning a steel ring: measuring and lofting on site in the main tunnel, determining the position of the tunnel door, fixing the embedded steel ring, and performing temporary reinforcement welding after the steel ring is positioned;

s1-3-2, planting the steel bars: punching holes and embedding bars at the positions of the steel rings, injecting glue in cooperation with bar embedding, inserting the stirring head into the bottom of the hole, and injecting 2/3 of the hole volume; the prepared steel bar is inserted into the bottom of the hole in a rotating mode, installation is carried out within the specified curing time, the anchoring agent is enabled to be evenly attached to the surface of the steel bar, and other work is carried out after the anchoring agent is cured; the embedded steel bars are threaded steel bars, the length of the embedded steel bars is 30-40 cm, and the diameter of the embedded steel bars is 16-20 mm; the hole depth is 20cm-30 cm;

s1-3-3, constructing a portal ring beam: after the steel bar planting is finished, erecting a formwork, binding steel bars, installing a pre-embedded grouting guide pipe and a water-swelling rubber strip, pouring concrete, removing the formwork and maintaining; the template is made of bamboo plywood with the thickness of 10mm-20mm and is fixed by wood nails; an elastic gasket is arranged between the templates for sealing and pressing; the ring beam steel bars of the tunnel door are welded with the embedded steel bars; the concrete is continuously poured in a layered symmetrical way; the concrete is fed by a hopper, and the concrete is conveyed into a tunnel by an electric power cart and manually conveyed into a mold for pouring; vertically pouring in layers with the layer height of 40-50 cm, symmetrically pouring and tamping two sides, and controlling the height difference of concrete surfaces on two sides; the concrete is poured by adopting a flat vibrator or an inserted vibrator for vibration, and when the height difference of the free falling of the concrete is more than 3m, a string cylinder is arranged; after the concrete is poured, curing is carried out after final setting, the curing method is watering curing, after the concrete is poured, covering and watering are carried out within 12 hours, and the surface of the concrete is kept wet during curing;

s1-3-4, chiseling the central knife area of the tube piece: after the strength of the concrete reaches the design strength, before starting, the pipe piece in the central cutter area of the pipe jacking machine is manually chiseled.

Preferably, step S1-4 includes the steps of:

s1-4-1, hoisting and descending the trolleys sequentially in sequence, wherein the starting end side is a # 1 rear matched trolley, a # 2 rear matched trolley, a # 3 rear matched trolley and a # 4 rear matched trolley, and the receiving end side is a # 5 rear matched trolley, and assembling; a high-voltage switch cabinet, a high-voltage cable branch box, a transformer and a mixed liquid box are arranged on the right side of the 1# rear matching trolley; a water tank, a water pump and an electric appliance cabinet are arranged on the left side of the 1# rear matching trolley; foam stock solution, a compensation cabinet and a main control room are arranged on the right side of the 2# rear matched trolley, and an air storage tank, an air compressor and a hydraulic pump station are arranged on the left side of the 2# rear matched trolley; the 3# rear matching trolley frame comprises No. 1, No. 2, No. 3 and No. 4 upright columns, a front crescent plate, a rear crescent plate, a top material transportation assembly, a rear supporting assembly, an oil cylinder support, a push bench supporting assembly, an originating sleeve assembly, a trolley wheel pair and a push bench host; a power distribution cabinet, a slurrying machine, a cement paste, water glass and material hoisting system are arranged on the left side of the 4# rear matched trolley; the No. 5 rear matching trolley comprises a frame, a receiving steel sleeve and a receiving end hydraulic pump station;

s1-4-2, connecting the originating sleeve with the host;

s1-4-2-1, before the starting sleeve is connected with the host, completing shield tail brush welding, grease smearing and gap block welding construction; finishing the smearing of grease on the hand after the shield tail brush is welded, wherein the smearing amount of the grease on each tail brush is not less than 4 kg;

s1-4-2-2, hoisting the starting sleeve and the host to the upper part of the tool for positioning and reinforcing, and preparing the pump station in place;

s1-4-2-3, jacking the main machine to a designated position, welding and reinforcing, operating the pump station to push the main machine into the starting sleeve, and fixing the main machine and the starting sleeve after pushing to the designated position;

s1-4-2-4, after aligning the starting sleeve with the embedded steel ring, performing full-length welding sealing treatment, performing flaw detection and sealing test after welding, and performing starting operation after meeting requirements;

s1-4-2-5, oil cylinder support adjustment, starting sleeve and host reinforcement and anti-bump device installation.

Preferably, step S1-5 includes the steps of:

s1-5-1, starting sleeve filling: after the welding of 3# platform truck was accomplished, pour into the bentonite mud into in the initial sleeve, the bentonite mud is according to the bentonite: preparing water according to the mass ratio of (1: 10) to (1: 6); uniformly stirring sodium bentonite and water by using a mechanical stirring barrel, and then driving the mixture into a grouting pipe for grouting;

s1-5-2, receiving sleeve filling: and after the receiving sleeve is welded, the filling construction is finished, the filling material adopts commercial slurry, and the filling material is pumped into the receiving sleeve by a synchronous slurry vehicle.

Preferably, in step S2, the push force of the push bench is 3000kN-5000kN, the torque is 600kN · m-1000kN · m, the push speed of the push bench is 1-2mm/min, the rotating speed of a cutter head is 1-1.2rpm, the opening of a gate of the screw machine is not more than 20%, and the soil discharging amount is controlled to be 98-100% in the pushing process; the duct piece of the communication channel consists of an upper pipe joint and a lower pipe joint, the pipe joint with the central angle of 150 degrees and the pipe joint with the central angle of 210 degrees are combined in a blocking mode, the duct piece is assembled in a staggered joint mode, and the joint is sealed by a water-swelling water stop strip; the thixotropic slurry material comprises bentonite, alkali, polyacrylamide and water; in the grouting after the wall, the mass ratio of water in the cement paste to cement is 0.5-2, the volume ratio of water in the water glass solution to water glass is 0.5-2, and the volume ratio of the cement paste to the water glass solution in the double-liquid slurry is 0.5-2.0.

Preferably, step S3-2 includes the steps of:

s3-2-1, measuring a release point and positioning a steel ring: measuring and lofting on site in the main tunnel, determining the position of the tunnel door, fixing the embedded steel ring, and performing temporary reinforcement welding after the steel ring is positioned;

s3-2-2, planting the steel bars: punching holes and embedding bars at the positions of the steel rings, injecting glue in cooperation with bar embedding, inserting the stirring head into the bottom of the hole, and injecting 2/3 of the hole volume; the prepared steel bar is inserted into the bottom of the hole in a rotating mode, installation is carried out within the specified curing time, the anchoring agent is enabled to be evenly attached to the surface of the steel bar, and other work is carried out after the anchoring agent is cured; the embedded steel bars are threaded steel bars, the length of the embedded steel bars is 30-40 cm, and the diameter of the embedded steel bars is 16-20 mm; the hole depth is 20cm-30 cm;

s3-2-3, constructing a portal ring beam: after the steel bar planting is finished, erecting a formwork, binding steel bars, installing a pre-embedded grouting guide pipe and a water-swelling rubber strip, pouring concrete, removing the formwork and maintaining; the template is made of bamboo plywood with the thickness of 10mm-20mm and is fixed by wood nails; an elastic gasket is arranged between the templates for sealing and pressing; the ring beam steel bars of the tunnel door are welded with the embedded steel bars; the concrete is continuously poured in a layered symmetrical way; the concrete is fed by a hopper, and the concrete is conveyed into a tunnel by an electric power cart and manually conveyed into a mold for pouring; vertically pouring in layers with the layer height of 40-50 cm, symmetrically pouring and tamping two sides, and controlling the height difference of concrete surfaces on two sides; the concrete is poured by adopting a flat vibrator or an inserted vibrator for vibration, and when the height difference of the free falling of the concrete is more than 3m, a string cylinder is arranged; after the concrete is poured, curing is carried out after final setting, the curing method is watering curing, after the concrete is poured, covering and watering are carried out within 12 hours, and the surface of the concrete is kept wet during curing;

s3-2-4, chiseling the central knife area of the tube piece: after the strength of the concrete reaches the design strength, the pipe piece in the central cutter area of the pipe jacking machine is manually chiseled off before receiving.

Preferably, in step S3-4, a plurality of injection holes are reserved on the steel sleeve, a thick slurry injection hole and a double-slurry injection hole are reserved at the top of the steel sleeve, a pressure relief hole is reserved at the lower part of the steel sleeve, and ball valves with corresponding sizes are mounted; the steel sleeve barrel is made of a steel plate, longitudinal and circumferential rib plates are welded on the periphery of each section of barrel, and a flange is welded on the joint surface of each section of barrel; before receiving, reserving a grouting hole and a pressure gauge on the assembled steel sleeve by the push bench, and supplementing grouting into the steel sleeve by using the reserved grouting hole, wherein the grout is bentonite grout; when the push bench enters the steel sleeve, leakage occurs at the local seam of the steel sleeve, the drainage is performed on site by adopting a drainage tube, and according to the leakage condition, an improved material is injected into the cutter head to improve the slag soil and seal and stop water.

Preferably, in step S3-5, after the steel sleeve is initially filled, opening two pressure relief ports reserved on the steel sleeve, connecting a top pressure relief port to a grouting pipe, performing mud adding and pressurization by using a mud pressing trolley, wherein the slurry is bentonite slurry, paying attention to the pressure in the bin before injection, observing the pressure in the sleeve of the bin to be not less than 0.25MPa, keeping the pressure loss to be not more than 0.05MPa without leakage for a period of time, and completing receiving the sleeve; if leakage occurs, blocking the tissue, and continuously performing a pressure maintaining test until the pressure meets the requirement; when the pressure in the sleeve is less than 0.27MPa, the tissue is stirred into slurry, and the pressure is supplemented to 0.35MPa and then the tissue is stopped; before cutting the pipe piece, the preparation work of pressure maintaining and grouting is done, the pressure change of the receiving sleeve is concerned in the cutting process of the cutter head, and when the pressure is less than 0.27MPa, the slurry is organized and supplemented.

Preferably, step S3-6 includes the steps of:

s3-6-1, before the push bench arrives: determining the mileage of the cutter head from the concrete segment through measurement; the pipe jacking machine enters a tunneling state when reaching the mileage, and the ground settlement condition is monitored at the frequency of once every two hours; before the cutter head of the pipe pushing jack is not contacted with the concrete pipe piece, the thrust, the propulsion speed and the cutter head rotating speed of the pipe pushing jack are controlled; the push force of the push bench is 3000kN-5000kN, the push speed of the push bench is 3-5mm/min, and the rotating speed of the cutter head is 1-1.2 rpm;

s3-6-2, segment cutting: properly reducing the propulsion parameters in the segment cutting stage of the pipe jacking machine, and taking the lower limit value of the tunneling construction parameter range, wherein the head posture of the pipe jacking machine is 30-50 mm higher than the axis and is in a head-up posture; the horizontal posture is within +/-20 mm;

s3-6-3, tunneling in a steel sleeve: the tunneling speed in the steel sleeve is less than 5mm/min, and the rotating speed of the cutter head is reduced to 0.5 rad/min-1 rad/min; and during tunneling, the attitude of the pipe jacking machine during tunneling in the steel sleeve is controlled by taking the actually measured installation center line of the steel sleeve as the reference, and the deviation of the center line is controlled within 20 mm.

The invention has the beneficial effects that:

1) the invention provides a mechanical method communication channel construction method utilizing a pipe jacking technology, which comprises construction preparation, pipe jacking starting, tunneling construction and pipe jacking receiving construction, wherein the construction preparation stage comprises track laying in a main tunnel, hydropower installation, grouting reinforcement of the main tunnel, manufacture of a starting tunnel door ring beam, assembly positioning and sleeve connection of a 1# rear supporting trolley, a 2# rear supporting trolley, a 3# rear supporting trolley (comprising a starting sleeve and a host), a 4# rear supporting trolley and a 5# rear supporting trolley (comprising a receiving sleeve), and starting and receiving sleeve filling; the construction stages of pipe jacking starting and tunneling comprise starting parameter control, tunneling parameter control, pipe joint assembly, antifriction grouting, grouting after wall and attitude control; the pipe jacking receiving construction stage comprises receiving construction preparation, receiving tunnel door ring beam construction, receiving sleeve installation, sleeve joint sealing treatment, steel sleeve warehouse filling and pipe jacking machine tunneling. The assembled connection channel structure and the pipe jacking method have the advantages of high construction mechanization degree, reliable quality, high speed, no need of soil body pre-reinforcement, low manufacturing cost, small environmental disturbance and the like.

2) The small-diameter earth pressure balance push bench and the rear supporting equipment adopted by the invention are integrally designed with the tunnel inner support system, so that tunneling, segment assembling, slag discharging, feeding and grouting in the tunnel construction process are realized, and full-mechanized operation is realized. The inner support system is provided with an oil pressure automatic regulating device, so that the jacking force of the support oil cylinder can be automatically regulated along with the stress change of the tunnel, and the automatic service can be comprehensively realized.

3) The segment of the interval tunnel in the connection passage of the invention adopts a reinforced concrete composite segment splicing structure and adopts glass fiber reinforced concrete. The connecting channel is formed in one step by assembling pipe pieces, the pipe sections are divided into an upper prefabricated part and a lower prefabricated part, staggered joints are assembled, wedge-shaped amount is avoided, water stopping is realized by adopting a water-swelling water stop strip at the joint, and the waterproof effect is good.

4) The main tunnel and the communication channel are arranged in a T-shaped joint mode, the hole ring for the communication channel to enter and exit is designed to be a steel pipe piece, the gap between the main tunnel and the channel pipe piece is filled with grouting, the connecting steel plates are fully welded, and the reinforced concrete beam is poured on the outer side, so that reasonable stress and safety of the structure are ensured.

Drawings

FIG. 1 is a schematic diagram of a subway communication channel;

FIG. 2 is a schematic view of the upper and lower pipe sections of the communication channel;

FIG. 3 is a flow chart of a mechanical method connecting channel construction process using pipe jacking technology;

fig. 4 is a schematic diagram of the position of the communication channel in the second embodiment.

Description of reference numerals: the tunnel comprises a main tunnel 1, a communication channel 2, a portal ring beam 3, a steel pipe sheet 4, an upper pipe joint 5, a lower pipe joint 6, a 1# communication channel 7, a 2# communication channel 8, a 3# communication channel 9, a Yunzhang high-speed railway station 10, an intermediate air shaft 11 and a shield working well 12.

Detailed Description

The present invention will be further described with reference to the following examples. The following examples are set forth merely to aid in the understanding of the invention. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.

The invention provides a mechanical method communication channel construction method by using a pipe jacking technology, which comprises the steps of firstly, laying a track in a main tunnel, installing water and electricity, grouting and reinforcing the main tunnel, and manufacturing a portal ring beam; then the 1# rear matched trolley, the 2# rear matched trolley, the 3# rear matched trolley (containing the initial sleeve and the host), the 4# rear matched trolley and the 5# rear matched trolley (containing the receiving sleeve) are assembled and positioned and connected with the sleeve, and then the sleeve is filled. Secondly, tunneling construction, pipe joint assembly, antifriction grouting, grouting after wall, and control of the posture of the pipe jacking in the tunneling process are carried out by setting reasonable pipe jacking starting and tunneling parameters. And finally, preparing receiving construction preparation before arrival, receiving portal ring beam construction, installing a receiving sleeve, sealing the joint of the receiving sleeve, filling a steel sleeve of the warehouse, cutting the duct piece out of the tunnel, and tunneling in the steel sleeve. The invention greatly improves the construction safety of the communication channel, improves the construction efficiency, reduces the adverse effect on the environment caused by construction, and particularly fully embodies the superiority when the construction is carried out in the poor strata such as extremely soft, broken and water-rich strata. Meanwhile, the mechanical equipment has long service life, can be used in a circulating way, has simple working procedures, short construction period and high speed, and the investment in the construction process is relatively low, so that the number of communication channels is increased, the construction cost is lower, the economic benefit is more obvious, and the safety, economic and environmental protection benefits are remarkable.

Example one

The embodiment of the application provides a mechanical method communication channel construction method utilizing a pipe jacking technology, which comprises construction preparation, pipe jacking starting, tunneling construction and pipe jacking receiving construction, wherein the construction preparation stage comprises track laying in a main tunnel 1, hydropower installation, grouting reinforcement of the main tunnel, manufacture of an initial tunnel door ring beam, assembly positioning and sleeve connection of a 1# rear supporting trolley, a 2# rear supporting trolley, a 3# rear supporting trolley (comprising an initial sleeve and a host), a 4# rear supporting trolley and a 5# rear supporting trolley (comprising a receiving sleeve), and starting and receiving sleeve filling; the construction stages of pipe jacking starting and tunneling comprise starting parameter control, tunneling parameter control, pipe joint assembly, antifriction grouting, grouting after wall and attitude control; the construction stage of receiving the jacking pipe comprises receiving construction preparation, receiving tunnel portal ring beam construction, receiving sleeve installation, sleeve joint sealing treatment, steel sleeve warehouse filling, and tunneling of the jacking pipe machine (the jacking pipe machine reaches the front, a segment cutting stage and tunneling in the steel sleeve). The method specifically comprises the following steps:

1. preparation for construction

(1) Arrangement in main tunnel

1) Track laying: and after the construction of the main tunnel is finished, paving a track according to the track gauge of the pipe jacking machine trolley. If the track gauge of the trolley is the same as that of the main tunnel storage battery car, the trolley does not need to be paved again, but the track needs to be reinforced. After the tracks are laid, a track board is arranged in the middle of the double tracks and fixed by iron wires.

2) Hydroelectric installation: and a water supply pipe and a water discharge pipe are respectively arranged in the main tunnel, and the water supply pipe and the water discharge pipe adopt DN80 galvanized steel pipes. Two circuits need to be arranged on the tunnel at the starting side, one circuit in the circuits is a 10kV high-voltage cable, the other circuit is a lighting circuit, and the lighting circuit adopts an LED lamp strip. One low-voltage power cable is required to be arranged in the receiving side tunnel.

(2) Grouting reinforcement for main tunnel

And (3) lining the front and rear 5 rings of the starting and receiving ends of the connecting channel and the position of the connecting channel to carry out grouting reinforcement, wherein the grouting adopts cement paste and water glass solution, and the design formula is shown in the table 1. The cement slurry is P.O 42.5.5 ordinary acid salt cement, the Baume degree of the water glass is 35-40 degrees, and tap water is used as water.

TABLE 1 slurry mixing ratio Table

(3) Starting tunnel portal ring beam manufacturing method

Firstly, measuring a placing point and positioning a steel ring:

and (4) performing field measurement and lofting in the main tunnel, determining the position of the tunnel portal, fixing the embedded steel ring, and performing temporary reinforcement welding after the steel ring is positioned.

② planting bars

Punching and bar planting are carried out at the position of the steel ring, glue injection is carried out in a matched mode during bar planting, glue injection is carried out on the bottom of the stirring head inserting hole, and 2/3 of the hole volume is filled. And (3) rotating the prepared steel bar and slowly inserting the steel bar into the bottom of the hole, installing the steel bar within the specified curing time, so that the anchoring agent is uniformly attached to the surface of the steel bar, and performing other work after the anchoring agent is cured. The embedded steel bar adopts a threaded steel bar, the length of the embedded steel bar is 30cm-40cm, the diameter is 16mm-20mm, and the hole depth is 20cm-30 cm.

Construction of ring beam of tunnel door

After the bar planting is finished, erecting a formwork according to the portal ring beam drawing, binding steel bars, installing a pre-embedded grouting guide pipe and a water-swelling rubber strip, pouring concrete, removing a formwork and maintaining. The template adopts 10mm-20mm thick bamboo plywood, and no matter two adjacent bamboo plywood transversely piece together seam or vertically piece together seam, guarantee to overlap joint on same root square timber, establish the dowel and fix, avoid appearing the wrong joint. An elastic gasket is arranged between the templates for sealing and pressing, so that the joints of the templates are ensured to be closely attached. And the ring beam steel bars of the tunnel door are welded with the embedded steel bars. The concrete strength grade is C40, the impermeability grade is P12, and the continuous casting is symmetrical in layering. The concrete is fed by a hopper, and the concrete is conveyed into the tunnel by an electric power cart and manually conveyed into a mold for pouring. And vertically pouring in layers, wherein the layer height is about 40-50 cm, symmetrically pouring and tamping the two sides, and controlling the height difference of the concrete surfaces on the two sides. The concrete is poured by adopting a flat plate vibrator or an insertion vibrator for vibrating, and when the height difference of the free falling of the concrete is more than 3m, a string cylinder is arranged to prevent the concrete from being separated. The time for removal of the formwork depends on the strength of the concrete, and the load-bearing formwork must have a given strength before removal. And (3) after the concrete is poured, timely curing is carried out after final setting, the curing method is watering curing, and after the concrete is poured, covering and watering should be carried out within 12 hours to keep the surface of the concrete wet during curing.

Chiseling out central knife area of duct piece

After the strength of the concrete reaches the design strength, before starting, the pipe piece in the central cutter area of the pipe jacking machine is manually chiseled, and the chiseling depth is 20 cm.

(4) Device positioning and sleeve connection

Hoisting and descending the trolleys in sequence, wherein the starting end side is a 1# rear matched trolley, a 2# rear matched trolley, a 3# rear matched trolley (comprising a starting sleeve and a host), a 4# rear matched trolley, and the receiving end side is a 5# rear matched trolley (comprising a receiving sleeve), and assembling.

A high-voltage switch cabinet, a high-voltage cable branch box, a transformer and a mixed liquid box are arranged on the right side of the 1# rear matching trolley; the left side is provided with a water tank, a water pump, an electric appliance cabinet and the like.

Foam stock solution, a compensation cabinet and a main control room are arranged on the right side of the 2# rear matching trolley, and an air storage tank, an air compressor and a hydraulic pump station are arranged on the left side of the 2# rear matching trolley.

Supporting platform truck frame behind 3# includes 1, 2, 3, 4 stands, anterior crescent moon board, rear crescent moon board, top material transport subassembly, back supporting component (backplate), hydro-cylinder support (hydro-cylinder bracket), pipe pushing jack supporting component, the sleeve subassembly that starts, platform truck wheel pair, pipe pushing jack host computer.

The 4# rear matching trolley comprises a power distribution cabinet, a pulping machine, cement paste, water glass, a material lifting system and the like which are arranged on the left side.

The 5# rear matching trolley comprises a frame, a receiving steel sleeve, a receiving end hydraulic pump station and the like.

② the initial sleeve is connected with the host

The method comprises the following steps: before the starting sleeve is connected with the host, three shield tail brush welding, grease smearing and gap block welding constructions need to be completed. The method specifically comprises the following steps: and (3) finishing the smearing of hand greasing after the welding of the shield tail brush, wherein the total number of the shield tail brushes is three, about 54 steel wire brushes are needed in each brush, and in order to ensure that the grease smearing quantity of the steel wire brushes is not less than 4kg, about 648kg (about 2.5 barrels) of hand-smearing type shield tail grease is needed to be consumed.

Step two: the starting sleeve and the host machine are hoisted to the upper part of the tool for positioning and reinforcing, and the pump station is prepared in place.

Step three: the host machine is jacked to a designated position and welded and reinforced, a professional operates the pump station to slowly push the host machine into the starting sleeve, and after the host machine is pushed to the designated position, the host machine and the starting sleeve are fixed.

Step four: after the starting sleeve is aligned with the embedded steel ring, full-welding sealing treatment is required, flaw detection (ultrasonic or 100% magnetic powder flaw detection) and tightness test are carried out after welding is finished, and starting operation can be carried out after requirements are met.

Step five: the oil cylinder support adjustment, the starting sleeve and the host machine reinforcement and head-collision prevention device are installed.

(5) Originating and receiving sleeve silos

Starting sleeve filling

After the welding of 3# platform truck was accomplished, pour into the bentonite mud into in the initial sleeve, the bentonite mud is according to the bentonite: preparing water according to the mass ratio of (1: 10) to (1: 6); the sodium bentonite and water are stirred uniformly by a mechanical stirring barrel (positioned on the right side of a 4# trolley) and then are injected into a grouting pipe for grouting.

② receiving sleeve warehouse filling

After the receiving sleeve is welded, the filling construction needs to be completed, the filling material is commercial slurry according to the design requirement, the filling is pumped into the receiving sleeve by a synchronous slurry vehicle, and the matching quality of the slurry is as shown in table 2.

TABLE 2 slurry blend quality

Substance(s)	Cement (kg)	Bentonite (kg)	Water (kg)	Fly ash (kg)	Sand (kg)
						Quality of	80	150	450	250	850

2. Pipe-jacking originating and tunneling construction

(1) Originating parameter control

After the pipe jacking machine is sealed by the sleeve, concrete at a tunnel portal is cut to start, and tunneling parameters such as soil bin pressure, thrust, torque, propelling speed, cutter head rotating speed, grouting amount, screw machine gate opening, grease injection, soil discharge amount and the like are determined in the starting process.

The push bench has a push force of 3000kN-5000kN and a torque of 600 kN-1000 kN-m.

The push speed of the push bench is 1-2mm/min, and the rotating speed (rpm) of the cutter head is 1-1.2 rpm.

The opening degree of the screw machine gate is not more than 20 percent, and the opening degree of the gate is required to be opened and stopped when tunneling on a water-rich silt layer, so that the slag soil is discharged smoothly.

The theoretical soil output of the pipe jacking machine is as follows: v ═ pi × D²)÷4]And xL (wherein D is the diameter of a cave formed by the tunneling of the pipe jacking machine, and L is the length of the cave formed by the tunneling of the pipe jacking machine), and the soil output (without injected modifying materials and water in the stratum) in the propelling process is controlled to be between 98 and 100 percent.

(2) Tunneling parameter control

In the normal tunneling section, the propelling speed of the pipe jacking machine is controlled to be 20-30 mm/min, and other tunneling parameters are kept unchanged.

(3) Pipe joint assembly

The concrete strength grade of the lining ring is C50, the impermeability grade is P10, the whole ring is divided into two standard blocks (B1) and (B2), the staggered joint assembly is realized, and no wedge-shaped amount exists. The pipe section of the communication channel 2 is divided into an upper prefabricated design and a lower prefabricated design (namely an upper pipe section 5 and a lower pipe section 6), the combination form of the blocks is 1 x 150 degrees +1 x 210 degrees, and the weight of the single block is about 3.2t at most; the duct pieces are assembled by adopting staggered joints, and the joints are sealed by water-swelling water stop strips.

The pipe joints are placed on a pipe joint transportation platform according to the installation sequence through a crane, after the tunneling is finished, the pipe joints are sent to a pipe joint installation range through a pipe joint hoisting device to be installed, the pipe joints are tightly pushed by a pushing oil cylinder which extends out of a corresponding position in time after the pipe joints are installed in place, when the pushing force of the pushing oil cylinder is larger than the force required for stabilizing the pipe joints, a pipe joint installing machine is removed, the ovality of a lining ring is measured, longitudinal bolts are screwed down, and the pipe joint assembling quality standard is shown in a table 3.

TABLE 3 pipe joint assembling quality standard table

Serial number	Item	Allowable error
			1	Vertical axis deviation	±25mm
2	Deviation of horizontal axis	±25mm
			3	Pipe joint installation ring formation deviation	≤10mm
4	Height difference between adjacent pipe joint rings	≤4mm
			5	Opening of ring and longitudinal seam	≤2mm
6	Penetration rate of ring and longitudinal bolt	100％

(4) Antifriction grouting

And (3) adopting thixotropic slurry to carry out antifriction grouting in the tunneling process, filling a soil body gap with the thickness of 15mm on the outer wall of the pipe, calculating the grouting amount according to 1.3 times of the building gap, matching the grouting rate with the jacking rate, and taking the pressure of a grouting press-in opening as 1.2 gamma h. The main materials of the thixotropic slurry are bentonite, alkali, polyacrylamide and water, and the thixotropic slurry mainly plays roles in supporting soil and reducing drag.

(5) Grouting after the wall

After the push-in of the push bench is finished, the slurry sleeve can be replaced by hard slurry, the grouting hole is plugged, the hard slurry is double-liquid slurry of cement slurry and water glass solution, and the grouting pressure is controlled within 0.5 MPa. The mass ratio of water in the cement paste to cement is 0.5-2 in the grouting after the wall is poured; the volume ratio of water to water glass in the water glass solution is 0.5-2; the volume ratio of the cement paste to the water glass solution in the double-liquid slurry is 0.5-2.0.

(6) Attitude control

The maximum deviation of jacking of the jacking pipe is not more than +/-50 mm, and jacking can be started under the conditions that the pipe joints are well assembled and qualified after inspection and all machines are normally operated. And if the posture deviation occurs in the jacking process, the posture of the push bench is preferentially adjusted by adjusting the pressure distribution of the push oil cylinder, if the effect is not obvious, the deviation correction is strengthened by adjusting the hinging adjustment of the push pipe, and the deformation condition of the formed pipe joint needs to be closely concerned after the hinging is opened.

3. Pipe jacking receiving construction

(1) Receiving construction preparation

Before receiving, accurate measurement is carried out on the position of the pipe push bench, the relation between the central axis of the tunnel to be tunneled and the central axis of the tunnel design is determined, meanwhile, rechecking measurement is carried out on the steel pipe sheet at the position of the receiving tunnel door, and the through posture and the tunneling deviation rectifying plan of the pipe push bench are determined.

(2) Receiving hole door ring beam construction

The specific construction process refers to the construction of an initial tunnel portal ring beam.

(3) Receiving sleeve mounting

The receiving steel sleeve is divided into four sections, wherein the front end, the lengthening ring and the rear end are integrated rings, and the middle section is divided into an upper semicircle and a lower semicircle. The receiving sleeve is welded at the steel-concrete composite pipe piece for opening the hole. The tunnel is conveyed into the 5# trolley, the posture of the receiving sleeve is adjusted through the jack and the 20t chain block, and the front end of the sleeve and a reserved hole door (namely the range of the main tunnel 1 to be drilled) on the reinforced concrete composite pipe piece are welded into a whole from the inside of the sleeve. After the sleeve is connected in place, and after the loading of the supporting system is completed, the outer ring is reinforced, the reinforcing is supported by adopting 20 # I-steel (or steel plate splicing) along the axial direction and the annular direction of the sleeve, one end of the support is welded on the outer arc of the sleeve, and the other end of the support is supported on a duct piece or an external support ring.

(4) Sleeve joint sealing treatment

Welding is adopted between the receiving sleeve and the main tunnel steel pipe sheet, three circumferential seams and two longitudinal seams of the steel sleeve, the welding seams are tight and firm, after the welding is finished, the welding seam sealing water is detected, the welding seam quality is checked, and repair welding treatment is carried out in time when quality defects occur; and a steel sleeve longitudinal stiffening plate is added at the position of the steel pipe sheet partition plate, so that the connection strength of the steel sleeve and the steel pipe sheet is increased, and the requirement of the push bench on longitudinal thrust stress during receiving is met.

A plurality of injection holes are reserved on the steel sleeve, 3 injection holes are needed to be used, the rest injection holes are all plugged by steel plugs, a thick slurry injection hole and a double-slurry injection hole with large diameters are reserved at the top, a pressure relief hole is reserved at the lower part, and ball valves with corresponding sizes are all installed. The steel sleeve barrel material uses a Q235 steel plate with the thickness of 30mm, the periphery of each section of barrel is welded with longitudinal and circumferential rib plates to ensure the rigidity of the barrel, the thickness of the rib plates is 20mm, the height of the rib plates is 45mm, the interval is about 300 multiplied by 350mm, each section of joint surface is welded with a flange, the flange uses a Q235 plate with the thickness of 30mm, the flange is connected by adopting a 10.9-grade M20 bolt, and an O-shaped sealing strip is added in the middle.

And (3) reserving a grouting hole and a pressure gauge on the assembled steel sleeve before receiving by the push bench, and timely supplementing grouting into the steel sleeve by using the reserved grouting hole, wherein the grout is mainly bentonite grout. When the push bench enters the steel sleeve, leakage occurs at a local joint of the steel sleeve, a drainage tube is adopted on site for drainage, and TAC improved materials are injected into the cutter head as necessary according to the leakage condition to improve the residue soil and seal water.

(5) Steel sleeve filling bin

And stopping tunneling when the distance between the cutter disc and the receiving end pipe piece is 500mm, after the steel sleeve is assembled, filling the steel sleeve, wherein the filling material is mortar (sand, water, bentonite and fly ash), pumping the mortar into the steel sleeve by using an extrusion pump until the steel sleeve is completely filled, and performing a sealing test.

After the steel sleeve is initially filled in a bin, opening two reserved pressure relief ports on the steel sleeve, connecting a top pressure relief port into a grouting pipe, performing mud adding and pressurization by adopting a high-speed automatic mud-pressing trolley, wherein the pressure of pressurized grouting is 0.35MPa, the grout is bentonite grout, closely paying attention to the pressure in the bin before injection, observing the pressure in the bin sleeve to be not less than 0.25MPa, keeping the pressure loss to be not more than 0.05MPa after no leakage occurs for 30 minutes, and receiving the sleeve; and if leakage occurs, immediately blocking the tissue, and continuously performing a pressure maintaining test until the pressure of 0.25MPa meets the requirement.

When the pressure in the sleeve is less than 0.27MPa, the slurry is immediately stirred, and the pressure is stopped when the pressure is supplemented to 0.35 MPa. Before cutting the pipe piece, the preparation work of pressure maintaining and grouting is done, the pressure change of the receiving sleeve is closely concerned in the cutting process of the cutter head, and when the pressure is less than 0.27MPa, the tissue is immediately repaired.

(6) Pipe jacking machine reaching and tunneling

Firstly, the push bench arrives before

Before the push bench arrives, the mileage of the cutter disc from the concrete segment is determined through measurement. When the pipe jacking machine reaches the mileage, the pipe jacking machine enters a tunneling state, and the ground settlement condition is monitored at the frequency of once every two hours. Before the cutter head of the pipe jacking machine is not contacted with the concrete pipe piece, the tunneling parameters such as the thrust force, the propelling speed, the rotating speed of the cutter head and the like of the pipe jacking machine are strictly controlled, and the good receiving posture is ensured when the pipe jacking machine is in contact with the wall. The push force of the push bench is 3000kN-5000kN, the push speed of the push bench is 3-5mm/min, and the rotating speed (rpm) of the cutter head is 1-1.2 rpm.

② segment cutting stage

The push parameters are properly reduced in the segment cutting stage of the push bench, the lower limit value of the tunneling construction parameter range can be taken, the head posture of the push bench is 30-50 mm higher than the axis, and the push bench is slightly raised upwards; the horizontal posture is within +/-20 mm.

Third, tunneling in steel sleeve

The tunneling speed in the steel sleeve is less than 5mm/min, and the rotating speed of the cutter head is reduced to 0.5 rad/min-1 rad/min. During tunneling, the attitude of the pipe jacking machine during tunneling in the steel sleeve is controlled by taking the actually measured installation center line of the steel sleeve as the reference, the deviation of the center line is controlled within 20mm, the tunneling speed is less than 5mm/min, and the rotating speed of a cutter head is reduced to 0.5 rad/min-1 rad/min.

Example two

The left line length of a shield interval between a Hangzhou high-speed railway station-a small village and town station of a Hangzhou inter-sea-city railway project is 3126.22m, and the starting mileage is as follows: ZDK0+437.570, end point mileage: ZDK3+563.487, long chain 0.303 m; the left-allowable shield interval right line length is 3126.555m, and the starting point mileage is as follows: YDK0+437.570, end point mileage: YDK3+563.847, long chain 0.278 m. The minimum curve radius of the line is 800m, the maximum curve radius is 4000m, the tunnel buried depth is 7.6-25 m, the line spacing is 10.8-16 m, and the maximum longitudinal slope is 28 per mill. In the interval, 3 mechanical method communication channels are arranged on a left DK0+785.000 (right DK0+787.798), a right DK1+237.420 (left DK1+239.019) and a right DK1+800.000 (left DK1+ 801.599).

As shown in FIG. 4, the mileage of the center of the 1# communication channel 7 is left DK0+785.000 (right DK0+787.798), the rail surface of a main tunnel is-22.647 (-22.689), the center elevation of the communication channel is-20.597 (-20.639), the thickness of lining top covering soil is about 24.1m, and the line spacing is 13.0 m; the central mileage of the 2# communication channel 8 is right DK1+237.420 (left DK1+239.019), the rail surface of a main tunnel is-25.464 (-25.463), the central elevation of the communication channel is-23.414 (-23.414), the thickness of lining top covering soil is about 26.65m, and the line spacing is 13.0 m; the central mileage of the 3# communication channel 9 is right DK1+800.000 (left DK1+801.599), the rail surface of a main tunnel is-21.861 (-21.850), the central elevation of the communication channel is-19.811 (-19.800), the thickness of lining top covering soil is about 19.96m, and the line spacing is 13.0 m. Middle air shaft 11 is located between surplus hang high-speed railway station 10 and shield construction working well 12, and 1# contact passageway 7, 2

# contact passageway

8, 3# contact passageway 9 are located between surplus hang high-speed railway station 10 and middle air shaft 11.

1. Engineering geological conditions

The area is a fourth series covering layer, and lithology mainly comprises cohesive soil, silt and fine sand for rushing out the sea area, the alluvial area and the lake area. According to geological cause times and engineering characteristics thereof, the space vertical distribution of the fourth series of stratums along the field can be roughly divided into from top to bottom: filling soil or ploughing and planting soil with different thicknesses on the shallow surface layer; under the soil, sticky silt and silty clay for washing the sea area, sticky soil and silty soil for washing the lake area, sticky soil or silty sand for washing the sea area, and the like.

The 1# communication channel in this interval is mostly located at the fifth₄A powder sand layer partially located at_2-1The silty clay sandwiches the silty soil layer; the 2# communication channel is located at the most part of_2-1The silty clay sandwiches the silty soil layer; 3# communication channel large partIs located at_2-1The silty clay sandwiches the silty soil layer.

Table 4 field foundation rock soil partition and its characteristic table

2. Hydrogeological conditions

(1) Surface water

The surface water of the construction site belongs to a pond and river water system, the site geomorphic units are lake-rushing plains, and river nets in the site and the periphery are densely distributed and communicated with each other. The work point relates to a Qiaoshuo port with the surface water body mainly comprising a small river and mainly comprising the west side of the field. The topography along the line is relatively flat, the river water force gradient in the field is relatively small, the water flow velocity is slow, and the cross section of each river is relatively small, so that the net flow of the river in the field is relatively small, the river bed is basically not scoured, and the sedimentation is mainly used.

(2) Ground water

The groundwater has different supplement, path, drainage and water chemical characteristics due to different water-containing media, hydrodynamic characteristics and occurrence conditions, and the method is disclosed according to drilling: the types of groundwater within the exploration depth range can be mainly divided into fourth series loose soil pore diving and pore micro confined water.

The fourth series of loose soil pore diving

The fourth series of loose soil pore diving is mainly added in artificial filling and cohesive soil layers at the shallow part of a field, the burial depth of a stable water level is 0.1-3.0 m below the ground through the investigation, the water-rich and water-permeable property of the surface soil-filling water-containing layer group has anisotropy, the water permeability is good, and the water-rich and water-permeable property of the lower cohesive soil water-containing layer group has isotropy and is weak. The pore diving is mainly supplied by vertical infiltration of atmospheric precipitation and subsurface water body, the direct flow is slow, the discharge is mainly carried out in an evaporation mode and the direct flow is mainly discharged to the side of a nearby pond, the water level has obvious dynamic change along with seasons and climates, and the dynamic amplitude is generally about 1.0-1.5 m according to regional data.

② pore micro confined water

Pore micro confined water mainly exists in the lower part₄Silt and sand₃Powder sand and ninthly_3-1Fine sand and ninthly₄Covering cohesive soil layer on the round gravel layer to form a relative water-resisting layer, and inspecting₄Silt and₃is distributed among the powder and the sand_2-1A silty clay layer sandwiched between the silty soil layers, and₃powder sand and ninthly_3-1Fine sand and ninthly₄The eight parts are distributed among the round gravels₃Layer of powdery clay_2-1Powdery clay with powdery soil layer and₃the layered powdery clay is a relative water-resisting layer, the distribution continuity is poor, the hydraulic connection between the water-bearing layers in most regions is poor, ninthly_3-1Fine sand and ninthly₄No relative water barrier is locally distributed between the water-bearing layers of the gravel soil, and the upper and lower water-bearing layers are in direct contact or have overflow supply, so that the water-bearing layers can be divided into nine parts_3-1Fine sand and ninthly₄The gravelly soil is regarded as the same confined aquifer.

3. Structural design

The main tunnel communication passage adopts a special ring lining ring segment.

(1) The lining ring is a double-sided wedge-shaped universal ring, and the wedge amount is 40 mm.

(2) The lining ring is divided into 6 blocks, the blocks (K), (B1), (B2) and (A3) adopt reinforced concrete, the concrete strength grade is C50, the anti-permeability grade is P12, and the size and the reinforcing bars are the same as those of the lining ring (TR) pipe piece.

(3) Partitioning (A1)

H3,(A2)

H3 adopts reinforced bar + glass fiber reinforced concrete pipe.

The sheet M30, the concrete strength grade C50, the impermeability grade P12, the tensile strength of the glass fiber reinforced plastic is more than or equal to 450MPa, and the shear strength is more than or equal to 110 MPa.

(4)(A1)

H3,(A2)

H3 Structure except for additionally arranging embedded steel plates (A1P)

H3、(A2P))

The outside of H3 is the same as each corresponding building block of lining ring (TR).

(5) Pre-burying a steel plate material: steel plate-Q235B steel, steel bar phi-HRB 400 grade steel bar.

(6) The lining ring connection includes 16 circumferential seam connecting bolts (M30) and 12 longitudinal seam connecting bolts.

(7) The self-rotation angle requirement of the main tunnel special lining ring pipe sheet is less than or equal to 0.15 degrees, the mileage deviation of the left and right line hole-opening special lining is less than or equal to 0.3m, and the horizontal axis deviation requirement of the main tunnel is less than or equal to +/-25 mm.

The design of the pipe joint of the communication channel comprises the following steps:

(1) the method comprises the following steps that a ring of steel pipe joints are adopted at the starting position and the receiving position of a communication channel respectively, the length of each steel pipe joint is determined according to the actual length of the channel measured on site, whether the steel pipe joint for adjusting the length of the channel needs to be added or not is determined through design, and the width of each steel pipe joint is controlled to be 600-900 mm; the rest adopt reinforced concrete pipe joints, and the width of the pipe joints is 900 mm.

(2) The inner diameter of each pipe joint is 2760mm, the outer diameter of each pipe joint is 3260mm, the thickness of each pipe joint is 250mm, 10 longitudinal bolts are arranged on each ring of pipe joints M24, and 4 circumferential bolts are arranged on each ring of M24.

(3) The pipe joints are assembled by adopting staggered joints without wedge-shaped amount, and the joints are sealed by water-swelling water stop strips.

(4) The pipe section is prefabricated into an upper block and a lower block, and the weight of a single block is at most about 3.2 t.

(5) The concrete comprises reinforced concrete pipe joints, a concrete strength grade C50 and an anti-permeability grade P12.

(6) The mechanical performance grade of the reinforced concrete pipe joint connecting bolt is 5.8 grade, the mechanical performance grade of the nut is 5 grade, and the hardness HV of the washer is 140; the steel pipe joint is made of Q235B steel, the mechanical performance grade of the connecting bolt is 8.8, the mechanical performance grade of the nut is 8, and the hardness HV of the washer is 300.

4. Construction technique

A3 # connection channel in the surplus and allowable interval of Hangzhou inter-sea-city railway engineering is constructed by adopting a pipe jacking method, a first mechanical tunnel is communicated at 3 and 13 months in 2020, and the construction of 2 channels is completed in two seasons in 2020. By utilizing the construction process flow in the first embodiment and continuously improving and perfecting the construction process, a 'weak reinforcement, strong support, cuttable, totally closed, balance protection, strict water prevention' key construction technology is finally formed.

(1) Weak reinforcement technology

Weak reinforcement is mainly different from a freezing method and a full-section reinforcement method; through technical challenges of local grouting, water stopping grouting materials, proportioning tests and the like, a weak reinforcement comprehensive technology is formed. The main contents comprise: grouting and reinforcing the wall thickness of a main tunnel, micro-reinforcing grouting holes of a front tunnel portal during tunneling, filling and grouting the back of a duct piece after tunneling is finished, and performing water-stopping grouting and cross-type reinforcement on the front tunnel portal after a negative ring is removed.

The main tunnel back grouting reinforcement is implemented by supplementary grouting before construction, adopts double-liquid-slurry ratio, and has the functions of filling disturbance cracks of a soil body constructed in the main tunnel, filling synchronous grouting shrinkage gaps, and enhancing the integrity and uniformity of the stress of the soil body.

The double-fluid-slurry ratio is selected for micro-reinforcing grouting of the tunnel portal before tunneling, the double-fluid-slurry ratio has the functions of solidifying soil bodies around the tunnel portal, causing less stratum disturbance when a cutter disc cuts off a segment in the starting stage, preventing liquefaction and avoiding the head planting of a shield tunneling machine after the shield tunneling machine passes through the tunnel portal.

The single-slurry ratio is selected for filling and grouting at the back of the tunneled duct piece, the annular gap of 30mm between the diameter phi 3290mm and the outer diameter phi 3260mm of the duct piece is filled in time by a cutter head, and the method is similar to the conventional large shield synchronous grouting.

And (3) removing water-stopping grouting of the front portal of the negative ring by adopting double-liquid slurry, and utilizing 6 grouting holes reserved in the main tunnel and 10 spherical valve grouting heads reserved on the steel pipe sheet of the portal of the communication channel. The grouting heads of the ball valve are distributed on the head and the tail of the tunnel portal. And the grouting holes are crossed during grouting, so that the water blocking effect of the main tunnel and the connection channel interface position is ensured.

(2) Strong supporting technology

The main tunnel segment adopts the design of the steel-concrete composite segment at the portal position, and the ring joint and the longitudinal joint of the segment steel structure are connected into a whole by adopting deep-cut welding seams, so that the anti-deformation capability of the main tunnel structure after the contact channel opening is improved.

In the cutting process of the communication passage portal, the main tunnel structure is damaged, and the main tunnel needs to provide counter force in the cutting and propelling processes. In a structure like a "muzzle" complex stress conditions occur. In the experimental engineering, in order to ensure the structural safety and the tunneling counter-force, a set of tunnel internal support system is designed, 7 ring pipe sheets near a tunnel portal form integral support, the support counter-force is collected and monitored in real time and compared with modeling calculation data, and stress analysis is carried out according to various working conditions before propulsion, in the tunnel portal cutting process, when the tunnel portal is completely broken and the like. The inner supporting capacity is far larger than the stress of the main tunnel caused by stress failure and deformation, so that the safety and the reliability are ensured.

(3) Cutting technique

One of the core technologies of the mechanical method communication channel is a 'crossing' technology that a main tunnel segment is drilled upwards to enter a communication channel tunnel at the beginning and penetrates through the main tunnel segment to enter another main tunnel at the receiving. The method comprises 2 aspects that firstly, the main tunnel segment at the position of the connection channel opening is designed into the machinable glass fiber reinforced concrete, the strength of the main tunnel segment meets the requirements of stress and stability of the main tunnel, and the main tunnel segment has machinability. Secondly, in the development of construction equipment, on one hand, the cutter of the cutter head meets the requirement of cutting capacity; on the other hand, the pipe piece is a concave surface when starting, and is a convex surface when receiving, so the cutter head needs to have better inosculation, and the sliding or the difficult control of the posture of the shield machine is avoided. Based on the design, the cutter head adopts a profiling design, namely, the cutter head is designed into an outward convex arc shape, and the center position adopts an inward concave design so as to respectively correspond to the contact sliding of a concave surface during starting and a convex surface during receiving.

(4) Totally enclosed technology

A mechanical method communication channel is a technology of 'punching in a hole', the existing tunnel is punched by adopting a direct cutting method to finish the tunneling of the other tunnel, the leakage water and the stability of the stratum under various geological conditions of the deep buried stratum are inevitably solved, the starting and receiving are totally closed by adopting a conversion technology of a semi-sleeve tail sealing brush and a shield tail sealing brush, the tunneling is always in a totally closed state, and the sealing pressure of a sleeve and the sealing pressure of a tail brush are detected by adopting a punching experiment.

(5) Balance-keeping technology

Water and soil pressure balance is the basic principle of the shield method. The basic idea of the technology is to adopt soil pressure balance to keep the stratum stable and control the stratum settlement deformation, combine the conversion from the rigid structure to the flexible soil body at the position of the in-and-out hole, and inject polymer (bentonite is selected in the project) into the soil bin when the hole is entered, on one hand, the polymer is used as a slag soil improvement medium to mix the cut segment concrete fragments; and on the other hand, soil pressure is built to balance the water and soil pressure transmitted by the stratum after the tunnel segment in the interval is cut and broken.

One of the core technologies of the construction method is full sleeve receiving, and when a shield machine breaks a receiving end segment and enters the sleeve, corresponding balance pressure needs to be established in the sleeve. The receiving sleeve is filled with inert slurry, a grouting pipeline is installed at the same time, a grouting pressure pump is configured, and slurry in the sleeve is continuously supplemented in the receiving stage to maintain pressure, so that soil pressure balance in the receiving stage is realized.

(6) Strict waterproof technology

The mechanical method communication channel waterproof technology intensively embodies the multilayer physical sealing concept, and is continuation and deepening of the traditional shield waterproof engineering. The whole system is waterproof and is divided into 5 aspects: firstly, the section tunnel segment is in waterproof design of the reinforced concrete composite segment at the position of the communication channel; secondly, the waterproof design of the lining structure of the segment of the connecting channel is realized; thirdly, the sleeve starts to receive the sealed waterproof design; fourthly, waterproofing is carried out in the process of construction; fifthly, the tunnel portal is waterproof.

Claims

1. A mechanical method connecting channel construction method by using a pipe jacking technology is characterized by comprising the following steps:

s1, construction preparation;

s1-1, arranging in the main tunnel;

s1-3, manufacturing an initial tunnel portal ring beam;

s1-4, positioning equipment and connecting a sleeve;

s1-5, starting sleeve and receiving sleeve filling;

s2, starting a jacking pipe and performing tunneling construction;

s3, receiving construction by a jacking pipe;

s3-2, receiving the construction of the portal ring beam;

and S3-6, the pipe jacking machine reaches tunneling.

2. The method for constructing a mechanical communication channel by using pipe jacking technology as claimed in claim 1, wherein the step S1-1 comprises the steps of:

3. The method for constructing a mechanical communication channel by using pipe jacking technology as claimed in claim 1, wherein the step S1-3 comprises the steps of:

4. The method for constructing a mechanical communication channel by using pipe jacking technology as claimed in claim 1, wherein the step S1-4 comprises the steps of:

s1-4-2, connecting the originating sleeve with the host;

5. The method for constructing a mechanical communication channel by using pipe jacking technology as claimed in claim 1, wherein the step S1-5 comprises the steps of:

6. The method for constructing a mechanical communication channel by using a pipe jacking technique according to claim 1, wherein in step S2, the thrust of the pipe jacking machine is 3000kN-5000kN, the torque is 600 kN-m-1000 kN-m, the propelling speed of the pipe jacking machine is 1-2mm/min, the rotating speed of a cutter head is 1-1.2rpm, the opening degree of a screw machine gate is not more than 20%, and the soil discharging amount in the propelling process is controlled to be 98-100%; the duct piece of the communication channel consists of an upper pipe joint and a lower pipe joint, the pipe joint with the central angle of 150 degrees and the pipe joint with the central angle of 210 degrees are combined in a blocking mode, the duct piece is assembled in a staggered joint mode, and the joint is sealed by a water-swelling water stop strip; the thixotropic slurry material comprises bentonite, alkali, polyacrylamide and water; in the grouting after the wall, the mass ratio of water in the cement paste to cement is 0.5-2, the volume ratio of water in the water glass solution to water glass is 0.5-2, and the volume ratio of the cement paste to the water glass solution in the double-liquid slurry is 0.5-2.0.

7. The method for constructing a mechanical communication channel by using pipe jacking technology as claimed in claim 1, wherein the step S3-2 comprises the steps of:

8. The method for constructing a mechanical communication channel by using a pipe jacking technology as claimed in claim 1, wherein in step S3-4, a plurality of injection holes are reserved on the steel sleeve, a thick slurry injection hole and a double slurry injection hole are reserved at the top of the steel sleeve, and a pressure relief hole is reserved at the lower part of the steel sleeve, and ball valves with corresponding sizes are installed; the steel sleeve barrel is made of a steel plate, longitudinal and circumferential rib plates are welded on the periphery of each section of barrel, and a flange is welded on the joint surface of each section of barrel; before receiving, reserving a grouting hole and a pressure gauge on the assembled steel sleeve by the push bench, and supplementing grouting into the steel sleeve by using the reserved grouting hole, wherein the grout is bentonite grout; when the push bench enters the steel sleeve, leakage occurs at the local seam of the steel sleeve, the drainage is performed on site by adopting a drainage tube, and according to the leakage condition, an improved material is injected into the cutter head to improve the slag soil and seal and stop water.

9. The method for constructing a mechanical communication channel by using a pipe jacking technology according to claim 1, wherein in step S3-5, after a steel sleeve is initially filled in a bin, two pressure relief ports reserved on the steel sleeve are opened, a top pressure relief port is connected to a grouting pipe, a mud pressing trolley is used for carrying out mud pressing, the slurry is bentonite slurry, the pressure in the bin is concerned before injection, the pressure in the bin sleeve is observed to be not less than 0.25MPa, leakage does not occur for a period of time, the pressure loss is not more than 0.05MPa, and a receiving sleeve is completed; if leakage occurs, blocking the tissue, and continuously performing a pressure maintaining test until the pressure meets the requirement; when the pressure in the sleeve is less than 0.27MPa, the tissue is stirred into slurry, and the pressure is supplemented to 0.35MPa and then the tissue is stopped; before cutting the pipe piece, the preparation work of pressure maintaining and grouting is done, the pressure change of the receiving sleeve is concerned in the cutting process of the cutter head, and when the pressure is less than 0.27MPa, the slurry is organized and supplemented.

10. The method for constructing a mechanical communication channel by using pipe jacking technology as claimed in claim 1, wherein the step S3-6 comprises the steps of: