CN113236264A

CN113236264A - Split starting construction method for shield of small clearance, upper soft and lower hard stratum

Info

Publication number: CN113236264A
Application number: CN202110469237.4A
Authority: CN
Inventors: 王超银; 韩涛; 马亮亮; 陈勇超; 陈健
Original assignee: Traffic Engineering Branch of China Railway Sixth Group Co Ltd
Current assignee: Traffic Engineering Branch of China Railway Sixth Group Co Ltd
Priority date: 2021-04-28
Filing date: 2021-04-28
Publication date: 2021-08-10

Abstract

The invention relates to the technical field of shield tunnel engineering, in particular to a split starting construction method for a shield in a stratum with small clearance, soft upper part and hard lower part. A split starting construction method for shield tunneling in a small-clearance, upper-soft and lower-hard stratum comprises a construction process flow and operation key points. The construction method disclosed by the invention is already subjected to engineering practice, and in the process of project implementation, the narrow space limitation is solved through a series of construction process optimization and invention creation in combination with the actual conditions on site; through detailed geological exploration and combination with theoretical foundation, construction parameters such as tunneling parameters, soil output, grouting amount and the like are optimized, construction monitoring is strengthened, the technical difficulty of starting of a soft upper hard stratum and a hard lower hard stratum is overcome, high standards of quality zero defect, safety zero accident and ground surface near zero settlement are finally achieved, split starting of a shield of a small clearance, a soft upper hard stratum and a hard lower hard stratum is completed, and valuable experience is provided for subsequent similar construction.

Description

Split starting construction method for shield of small clearance, upper soft and lower hard stratum

Technical Field

The invention relates to the technical field of shield tunnel engineering, in particular to a split starting construction method for a shield in a stratum with small clearance, soft upper part and hard lower part.

Background

With the increase of the investment of national infrastructure and the continuous increase of urban traffic pressure, the shield tunnel engineering construction presents a larger growth trend, shield construction is carried out in large scale in each city, the stratum penetrated by the shield tunnel is more and more changeable, the construction environment is more and more complex, the types of encountered risk sources are more and more diversified, and the challenge of construction technology is more and more severe;

the left line of a shield zone from a shield working well of a first-stage engineering civil engineering second-work area of a Taizhou urban railway S1 line to a shield central station needs to adopt a form of split originating of a small clearance and upper soft and lower hard strata in the shield originating construction process, is the first project in China adopting split originating of the shield of the small clearance and upper soft and lower hard strata, and faces complex construction environment, extremely high construction technical difficulty, great construction safety risk and higher environmental protection and energy saving requirements.

Disclosure of Invention

The invention aims to provide a split starting construction method for shield in a small-clearance, upper-soft and lower-hard stratum, which aims to solve the existing problems: the engineering of split shield launching faces complex construction environment, extremely high construction technical difficulty, great construction safety risk and higher environmental protection and energy saving requirements.

In order to achieve the purpose, the invention adopts the following technical scheme:

a split starting construction method for shield of a small clearance stratum with a soft upper part and a hard lower part comprises a construction process flow and operation key points;

the construction process flow comprises the following steps:

reinforcing the stratum of the starting end;

installing an originating base;

assembling a rear matched trolley, descending the well, and moving the well into the underground excavation tunnel;

the shield machine is put into a well and assembled;

installing a reaction frame, sealing a tunnel portal, connecting a shield machine and debugging in a no-load way;

assembling negative ring pipe pieces, and grinding the glass fiber rib fender posts;

starting tunneling and load debugging;

backfilling and grouting after the shield tail is sealed through the tunnel portal;

the shield is tunneled for a first distance, and the equipment bridge is moved forwards into the tunnel;

dismantling the negative ring, erecting a steel support to form a semi-ring, and descending a well by using a trolley;

the shield continues to tunnel for a second distance, and a gantry crane and a large soil hopper are used for discharging residues;

the shield continues to tunnel for a third distance, and the trolleys 1#, 2#, and 3# move forwards into the tunnel;

the shield continues to tunnel for a fourth distance, and 4#, 5#, and 6# trolleys move into the tunnel;

and (4) enabling the trolley to completely enter the tunnel and enter a normal tunneling stage.

Preferably, the operation key points comprise split starting operation key points, semi-ring starting operation key points, upper soft and lower hard stratum tunneling parameter control key points and upper soft and lower hard stratum shield split starting technical measures.

Preferably, the split starting operation key point comprises that construction is carried out in a digging section before the shield body enters the soil body by adopting a gantry crane and small slag hopper unearthing mode; and when the starting wellhead space is large, constructing by adopting a gantry crane and a large muck bucket unearthing mode.

Preferably, the key points of the half-ring starting operation comprise a duct piece dismantling space, duct piece hoisting and negative ring duct piece reinforcing.

Preferably, the main control points of the tunneling parameters of the upper soft stratum and the lower hard stratum comprise geological exploration, development and control of tunneling parameters, soil output and synchronous grouting.

Preferably, the technical measures of split starting of the shield in the upper soft and lower hard stratum comprise a shield tunneling technical measure, a segment assembling technical measure, a grouting after wall technical measure and a monitoring and measuring technical measure.

Preferably, the operation key points also comprise quality control measures, and the quality control measures comprise segment entrance quality acceptance and segment stacking and transportation.

Preferably, the operation key points further comprise safety control measures, and the safety control measures comprise personnel configuration, before-class speech, emergency drilling and safety inspection.

Preferably, the operating point further comprises environmental protection and energy saving measures, and the environmental protection and energy saving measures comprise that full-time personnel are responsible for and comprehensively develop and establish civilized site activities and site management.

Preferably, the first distance is 16m/10 rings, the second distance is 9.6m/6 rings, the third distance is 32m/20 rings, and the fourth distance is 41.6m/26 rings.

The invention has at least the following beneficial effects:

the construction method has been carried out by engineering practice, and solves the problem of narrow space limitation by combining with the actual conditions on site and through a series of construction process optimization and invention creation in the project process; through detailed geological exploration and combination with theoretical foundation, construction parameters such as tunneling parameters, soil output, grouting amount and the like are optimized, construction monitoring is strengthened, the technical difficulty of starting of a soft upper hard stratum and a hard lower hard stratum is overcome, high standards of quality zero defect, safety zero accident and ground surface near zero settlement are finally achieved, split starting of a shield of a small clearance, a soft upper hard stratum and a hard lower hard stratum is completed, and valuable experience is provided for subsequent similar construction.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

FIG. 1 is a flow chart of the construction process.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

the construction process flow comprises the following steps:

reinforcing the stratum of the starting end;

installing an originating base;

the shield machine is put into a well and assembled;

starting tunneling and load debugging;

the shield is tunneled for a first distance of 16m/10 rings, and the equipment bridge is moved forward into the tunnel;

the shield continues to tunnel a second section of rings with the distance of 9.6m/6, and a gantry crane and a large soil hopper are used for discharging residues;

the shield continues to tunnel a third ring with a distance of 32m/20, and the trolleys 1#, 2# and 3# move forwards into the tunnel;

the shield continues to tunnel a fourth ring with a distance of 41.6m/26, and 4#, 5# and 6# trolleys move into the tunnel;

The operation key points comprise split starting operation key points, semi-ring starting operation key points, upper soft and lower hard stratum tunneling parameter control key points and upper soft and lower hard stratum shield split starting technical measures.

The split starting operation is characterized in that the starting well is constructed by adopting an open-cut and smooth method, the main structure is a 2-layer two-span rectangular frame structure, the clearance size of a shield hoisting hole is only 17.4m, and the shield hoisting hole is connected with a subsurface tunnel at the bottom of a goaf.

Because the starting vertical shaft is also used as a shield construction soil outlet, the hoisting space of the muck is limited, and the shield is provided with a plurality of holesThe tunneling section before the body enters the soil body adopts a gantry crane and a small slag hopper (6 m)³) Construction is carried out in a unearthing mode, and when the starting wellhead space is large, a gantry crane and a large residue soil hopper (22 m) are adopted³) "construction is carried out by unearthing mode, which is mainly divided into 7 stages, and the concrete description is as follows:

(1) the first stage is as follows:

and hoisting the starting bracket, the rear matched equipment, the shield tunneling machine and the reaction frame in sequence, and then descending into the well and installing.

(2) And a second stage:

the shield machine carries out equipment debugging, the pipeline connection between the lengthened shield body and the equipment bridge (at least 20m of pipeline connection is prepared), the shield body moves forwards, the cutter head is abutted to the face and the pile is ground, and the equipment bridge and the trolley continue to be left in the underground tunnel.

(3) And a third stage:

the shield body is connected with the equipment bridge through a pipeline, 10 rings (16m) are tunneled, and a slag discharging mode of matching a gantry crane and a small slag hopper is adopted in the stage. Because the space of the shield starting well mouth is narrow and small, at this stage, the clearance size of the reaction frame and the working well main structure is only 3.2m, meanwhile, the screw machine stretches out the reaction frame by 1.5m, the self-made 6-square small soil bucket is only adopted for slag discharge, and the pipe piece is assembled by hoisting the single block and the side edge in the well.

(4) A fourth stage:

and (4) removing the negative ring pipe piece (-8 rings to-3 rings and 6 rings in total), forming a semi-ring state, and installing a steel support. After the space condition possesses, with equipment bridge forward push to link to each other with the shield body, then through the semi-ring opening with a section of self-control shaped steel platform truck hoist and mount well that will make in advance, shaped steel self-control platform truck provides the holding power for equipment bridge, installs belt feeder action wheel and feed opening additional simultaneously on self-control platform truck, cooperates equipment bridge to adopt the belt feeder to go out soil, improves the efficiency of construction.

(5) The fifth stage:

and (3) tunneling again (6 rings are 9.6m) by adopting a slag discharging mode of a gantry crane and a small slag hopper, then hoisting a large soil hopper to go into the well, and changing into the slag discharging mode of the gantry crane and the large slag hopper. And (4) continuously tunneling 20 rings (32m) to provide space for the subsequent 1#, 2#, and 3# trolleys to enter the tunnel. At this stage, pipeline extension connections are considered.

(6) The sixth stage:

and pushing the 1#, 2#, and 3# trolleys into the shield tunnel, adjusting the self-made trolleys to be connected with the 3# trolleys, and matching with the shield machine to tunnel from 26 rings to 62 rings. At this stage, 4# and 5# trolleys still remain in the caved tunnel of the goat head mountain, and the 3# trolleys are connected with the 4# trolleys through lengthened pipelines.

(7) Seventh stage (enter normal heading stage):

4# and 5# trolleys are pushed into a shield tunnel, the 6# trolleys are hoisted and lowered into a well and pushed into the tunnel, the self-made trolleys are adjusted to the back of the 6# trolleys, a sewage tank of the 7# trolleys is refitted to the 6# trolleys, the 7# trolleys do not need to be used, and the normal tunneling stage is started.

The main operation points of the half-ring starting are as follows:

(1) the duct piece dismantling space:

in order to simultaneously guarantee the space requirements of hoisting and descending the well by a self-made trolley and deslagging by a large soil hopper in the later period, 6-ring negative-ring pipe pieces are planned to be dismantled, 8-ring to 3-ring negative-ring pipe pieces are dismantled respectively, each ring of pipe pieces is 1.6m, the total dismantling length is 9.6m, and the transverse clearance dismantling size is planned to be 5.4 m.

(2) Segment hoisting:

in the duct piece dismantling process, in order to guarantee dismantling efficiency, 6 ring pipes are dismantled and hoisted for 3 times, 2 blocks are in a group, and the middle part is fastened and connected into a whole through duct piece bolts. Each group of pipe pieces are hoisted by 2 points, namely 1 hoisting point is arranged in the middle of each pipe piece. The hoisting point is formed by drilling the pipe piece by a water drill with the diameter of 100 mm.

(3) Reinforcing the negative ring pipe piece:

in the shield tunneling process, in order to well control the shield posture, the range of the removed negative ring pipe piece is reinforced by steel support with the diameter of phi 609mm, the length of the negative ring pipe piece is 9.6m, the negative ring pipe piece and the left ring pipe piece and the right ring pipe piece are symmetrically arranged by the center line of the pipe piece, the center distance is 3m, and the space requirement of slag discharge of a large soil hopper can be met.

The tunneling parameter control key points of the upper soft and lower hard stratum are as follows:

the length of a left tunnel between a shield working well and a Taizhou central station is 474.124m (the long chain is 0.698m), the line spacing is 13.5-16.5 m, the buried depth of the tunnel is about 8.64-10.8 m, the minimum curve radius of a line plane is 3200m, and the maximum longitudinal slope is-22 per thousand. The tunnel mainly passes through the clay stratum, and 50m before the starting section passes through the upper soft and lower hard stratum (upper clay and lower tuff).

In the split launching process of the shield in the upper soft and lower hard stratum, the following measures can be adopted to overcome the faced difficulty:

(1) geological exploration: the advance plan is made, the geological reconnaissance work of the starting section is made in advance, the geological condition is known in detail, and the shield tunneling construction parameters are strongly guaranteed;

(2) drawing up and controlling tunneling parameters: performing practical data analysis by theoretical calculation and combining construction experience of previous similar strata, wherein the soil pressure is set to be 1.1-1.3bar, and the setting of the soil pressure is to avoid overlarge stratum settlement deformation caused by too small soil pressure; the thrust is set at 1700-2100T, the thrust is slowly increased according to the actual parameter condition, and formation deformation caused by excessive thrust amplitude is avoided; the cutter torque is set at 2300-3000Km, and the rotation speed of the cutter is not too high and is preferably set at 1.2-1.4rpm because the shield cutter is stressed unevenly in the upper soft and lower hard strata and is easy to cause severe abrasion; the propelling speed is preferably set to be 10-30mm/min, so that serious cutter head abrasion and large shield attitude deviation are avoided.

(3) Soil output: the split starting stage of the shield is long in time, and the geological of the upper soft and lower hard stratum is uneven, so that stratum settlement is easy to generate, and soil output control is strictly needed in the shield process. The control of the soil output adopts double-control indexes of weight and square amount, the theoretical slag output square amount of a single ring is calculated according to a theoretical basis, the actual measurement of the slag weight is mainly carried out through the actual measurement of the slag density and a gantry crane weighing system, and the control is preferably 114-118 m³。

(4) Synchronous grouting: according to the design requirements, the ordinary acid salt cement mortar with qualified quality is taken as a synchronous grouting material, and the synchronous grouting mixture ratio is screened and optimized through a multi-gradient test to form the following mixture ratio:

shield split starting synchronous grouting mix proportion of upper soft and lower hard stratum

The synchronous grouting amount of each ring is not less than 9m³Preferably 9-10m³And the dynamic adjustment is carried out according to the underground water condition and the shield slag tapping condition. The synchronous grouting pressure is controlled to be 2-4bar, and the grouting speed is matched with the tunneling speed. The segment is assembled in time, strict requirements on quality are controlled, and integrity and quality of the segment assembly are guaranteed by the segment tenon and the segment mortise.

1. Parameter summarization: aiming at the stratum with soft upper part and hard lower part, the shield split starting construction tunneling parameter

Reference is made to the following table:

split starting tunneling parameter of shield in upper soft and lower hard stratum

2. Secondary grouting: selecting cement and water glass double-liquid slurry, wherein the water-cement ratio is 0.8: 1-1: 1 (mass ratio), cement slurry: water glass 1:1 (volume ratio). After the pipe piece is separated from the shield tail by 3 rings, secondary grouting is immediately carried out, and the secondary grouting amount of each ring is 0.3-0.7 m³And the grouting pressure is not less than 1 Mpa. The hole gate plugging water-stop ring is made of cement and water glass double-liquid slurry, and the proportion is the same as above, so that the effects of plugging the rear and ensuring the subsequent synchronous grouting effect are achieved. Meanwhile, through secondary grouting, the quality can be well guaranteed, and the phenomena of tunnel water leakage and floating of the control duct piece are reduced.

3. Improving the residue soil: in the initial tunneling process of a soft upper hard stratum and a hard lower stratum, when the improvement of dregs is not good, the situations that the posture of the shield is difficult to control, the snake-shaped tunneling, the segment damage, the earth over-excavation and the like easily occur, and further the tunneling parameters are abnormal, and the normal tunneling of the shield is seriously influenced. In order to ensure that the muck has good workability and fluidity, aiming at the characteristics of the stratum, high-quality foam is selected for improving the muck; meanwhile, a polymer additive is prepared, and if underground water is large, a certain polymer can be added into the foam stock solution for improving the residue soil. In the aspect of shield tunneling control, the spiral rotating speed is controlled to be matched with the pressure of the soil bin, slag temperature management is enhanced, and the proportion and the injection amount of the slag soil modifier are dynamically adjusted.

The technical measures of split starting of the shield in the upper soft and lower hard stratum are as follows:

(1) shield tunneling technical measures:

according to the past shield construction experience and related theoretical knowledge, the following shield tunneling technical measures are adopted by combining the concrete conditions of the project:

firstly, monitoring the shield attitude by adopting an automatic tunnel guiding system and manual measurement assistance;

and secondly, controlling the tunneling direction by operating a thrust cylinder of the shield tunneling machine in a partitioning manner according to a segmented axis fitting control plan made according to line conditions and shield attitude information reflected by a guiding system and combining tunnel stratum conditions.

And thirdly, the slag discharge amount of the shield is strictly controlled, and the ground surface settlement caused by over excavation is avoided.

Fourthly, the area mainly penetrates through clay stratums, geological prediction needs to be done in the tunneling process, tunneling parameters need to be reasonably controlled, muck improvement needs to be optimized, and the mud cake phenomenon is prevented.

And fifthly, the front 50m of the starting section of the interval passes through the upper soft lower hard stratum, the propelling pressure and the tunneling speed are reasonably controlled, the snake-shaped tunneling is avoided, and the attitude deviation is overlarge.

Sixthly, tunneling a large longitudinal slope with the starting section of 22 per mill in the interval, wherein most of the longitudinal slope is in a clay stratum, the posture of the tunneling should be reasonably kept upward, the heading trend of the shield tunneling machine is offset, and the posture deviation is avoided from being too large.

And seventhly, adjusting and correcting the shield tunneling attitude by adjusting the pressure of each group of the thrust cylinders. In general, if the shield tunneling machine deviates by 20 mm from the design axis, deviation rectification is performed. The correction process is carried out gradually and cannot be completed at one time, the horizontal direction of each ring of correction is not more than 2 mm, and the vertical direction of each ring of correction is not more than 3 mm.

(2) The technical measures of segment assembly are as follows:

firstly, before assembling, measuring the gap between the shield tails, and selecting a proper segment assembling point position according to actually measured data.

And secondly, before assembly, cleaning mud blocks and slurry on the previous ring pipe piece to ensure that the ring surface is clean and has no sludge.

And thirdly, during assembly, the roundness of the primary lining ring is ensured, and the expansion sequence of the propulsion oil cylinder is consistent with the assembly sequence of the pipe pieces.

Fourthly, bolt three-time re-tightening: after each ring is pushed, the connecting bolt needs to be screwed down. The lower ring is tightened once when advancing. And (4) tightening the segment connecting bolt within 10 rings once every 3 rings of tunneling are completed.

(3) Grouting after the wall technical measures:

through multiple mixing ratio tests, the most appropriate mixing ratio of synchronous grouting slurry is selected, the initial setting time of the slurry is ensured to be matched with the shield tunneling speed, and the segment is prevented from floating upwards or deviating.

And secondly, in the shield tunneling process, the synchronous grouting amount and the grouting pressure are reasonably controlled, and the filling of gaps behind the segment walls is full.

And thirdly, selecting proper secondary grouting frequency according to the actual situation on site. If water leakage occurs, secondary grouting is adopted in time.

(4) Monitoring and measuring technical measures:

in order to accurately know the ground deformation condition when the shield starts, provide basis for shield construction and achieve information construction, the following measures are taken in the shield starting section for monitoring:

the method comprises the following steps of firstly, strengthening clearance convergence, vault settlement and ground surface settlement monitoring in a goaf underground tunnel, forming a monitoring daily report every day, and issuing monitoring data information in time;

secondly, building (structure) settlement monitoring: in the shield construction process, monitoring of a gantry crane foundation, an underground pipeline and a peripheral building at the end is enhanced;

increasing monitoring frequency: before construction, the original data is observed for many times, and the average value of the original data is taken as the original data, so that the accuracy of the original data is ensured. Increasing monitoring frequency on the basis of original monitoring during shield crossing, and gradually reducing monitoring times after settlement tends to be stable after shield crossing;

and fourthly, the measured data is collected and reported to the engineering department in time so as to know the construction current situation and the change condition of the corresponding area in time, determine new construction parameters, grouting amount and other information and instructions, and transmit the information and instructions to a shield manipulator, so that the shield is propelled to be adjusted correspondingly in time, and the construction safety of the shield tunnel is ensured.

And fifthly, adopting informatization construction, before construction, establishing a coordination linkage mechanism and an information transmission channel with units such as owners, supervisors, headquarters, third-party monitoring and the like, ensuring smooth information communication and creating conditions for the informatization construction.

1. And feeding back the monitoring information, feeding back the monitoring information in real time, and feeding back the shield construction monitoring information in time according to the specified monitoring frequency.

2. And monitoring and analyzing, namely performing real-time analysis and stage (week/month) analysis according to the monitoring and measuring data, scientifically and reasonably evaluating the disturbance condition of the stratum, the safety state of the shield tunnel and the like, and providing corresponding suggestions.

3. The shield construction monitoring is a conventional monitoring project and mainly aims at ground settlement within the influence range of ground reinforcing construction and shield construction, clearance convergence of a shield tunnel structure and vault settlement monitoring.

4. And (3) performing information construction, dynamically adjusting construction parameters according to the monitoring data and the analysis result, and taking targeted technical measures and emergency measures or starting related emergency programs according to an emergency plan.

Quality control measures are as follows:

checking and accepting the field entrance quality of the duct piece: arranging special personnel, organizing supervision, inspecting the incoming quality of the segment, detecting whether the intensity of the segment meets the design requirements, checking whether the segment has damages and cracks, and timely withdrawing the segment factory if the segment has defects.

Stacking and transporting the pipe pieces:

(1) and (3) stacking the pipe pieces, wherein the inner arc surfaces of the pipe pieces are required to be stacked upwards, the stacking height is not more than three, two wood base plates are placed between the pipe pieces, and the base plates are aligned up and down to ensure that the middle part is separated. The width direction of the pipe piece is aligned up and down and is not inclined. A safety requirement channel must be reserved between piles, and rain-proof measures are taken in the area where the water-swelling elastic sealing gasket is adhered.

(2) And (4) transporting the segments, wherein the segments which reach the age and are qualified through inspection are transported to the construction site by a flat car in a planned way. The transportation time of the pipe piece is tamped by a skid so as to prevent the pipe piece from generating harmful cracks or the ridge line part from being damaged. And (4) unloading the pipe piece to a special pipe piece stacking area by a gantry crane after the pipe piece arrives at the site. The segment stacking area is selected properly to avoid the fracture caused by the abnormal stress generated by the uneven settlement of the place and the deformation of the skid due to the dead weight.

(3) The waterproof pasting quality control of the pipe piece is realized, technical staff are organized to carry out technical interaction and training work on the waterproof pasting staff of the pipe piece, the technical level of operating staff is enhanced, and the waterproof pasting construction quality is improved.

Arranging a special person, organizing supervision, checking the entrance and the adhesion of the waterproof material of the segment, checking whether the water stop strip is firmly adhered in place, and timely enabling a segment adhesion worker to re-adhere if the water stop strip is not adhered.

(4) Checking the assembling quality of the duct pieces:

quality inspection, arranging quality inspectors to inspect the splicing quality of the pipe pieces, checking whether the pipe pieces are staggered and damaged, counting every day, analyzing and discussing with a captain in time and eliminating defects, and accumulating experience for subsequent construction.

Secondly, the segment splicing quality real-name system is realized for splicing, if splicing quality defects occur, a source can be traced, a responsible person can be found, meanwhile, the responsibility center of splicing personnel can be promoted, and the segment splicing quality is improved.

(5) And (4) checking the water leakage of the duct piece, arranging a quality inspector, counting the water leakage of the formed tunnel duct piece, issuing a quality correction notice sheet, requiring a work area to correct in time, and forming closed data after the quality inspector performs recheck to be qualified.

(6) And (4) rechecking and measuring the attitude of the formed tunnel segment, and arranging a measurer to manually retest the attitude of the formed tunnel segment after the shield segment is separated from the shield tail and stabilized, forming a report and reporting to a construction information exchange group.

(7) The ground monitoring special person is on duty, the special person is arranged to be on duty in a ground monitoring room for 24 hours, the tunneling parameters, the splicing point positions and the duct piece types are recorded, and the tunneling parameters, the splicing point positions and the duct piece types are analyzed and summarized by combining settlement data every day.

Safety control measures:

and (3) personnel allocation, wherein 2 full-time safety personnel are arranged on the site and are responsible for checking and supervising the safety production of the project, and the safety production policy of 'safety first, prevention first and comprehensive treatment' is adhered to.

Speaking before class, performing safety education on workers every day, emphasizing safety problems of wearing safety helmets, keeping certificates and going on duty, prohibiting taking a battery car, working at high altitude, hitting objects, hoisting safety and the like, and strengthening safety consciousness of workers

Emergency drilling, wherein before shield construction, an organization worker carries out emergency drilling of water burst at a tunnel portal and emergency drilling of ground surface settlement monitoring, and prevention is mainly carried out.

And (4) full inspection:

(1) and (3) power utilization safety inspection: and checking whether the power utilization of the electric box is grounded or not, whether the phenomenon of one gate with multiple machines exists or not, and the like, and if the problem exists, immediately informing the work area to correct and change, so that potential safety hazards are eliminated.

(2) Safety inspection of the gantry crane: whether the limiting of the gantry crane is normal, whether the gantry crane track is normal and the like are checked, if the limiting is in a problem, the work area is immediately informed of rectification, and potential safety hazards are eliminated.

(3) Safety inspection of the battery car: and checking whether the brake of the battery car is normal or not, and if the brake is normal, immediately informing the work area to correct and change. And potential safety hazards are eliminated.

(4) Daily safety inspection: at present, a full-time security officer needs to patrol the safety construction operation condition on site every day, carefully troubleshoot potential safety hazards and leave no dead angle.

(5) The main remarks are as follows:

the shield machine has the advantages that all brakes and clutches of the shield machine are sensitive and reliable in action, all instruments are intact, and display is accurate.

Secondly, the operation of the traveling crane, the concrete pumping equipment, the shield machine and the like is carried out by a special person with a certificate, so that the purpose of fixing the crane and the shield machine is achieved.

The crane, crane hook over-height limiter, moment limiter, hook safety, lifting weight indicator, etc. are complete, sensitive and effective, and the light and horn (alarm bell) are good and effective. The brake and the clutch are sensitive and reliable in action, various instruments are intact, and the display is accurate. The mechanical connecting piece is firm in fastening and good in lubrication; the oil in the hydraulic oil tank of the oil circuit system is sufficient and has no leakage. The specification and the strength of the steel wire rope meet the requirements, the steel wire rope is correctly used, and the lifting hook and the lifting ring have no crack, deformation, crevasse and repair welding, and abrasion do not exceed the standard.

And fourthly, the inspection and maintenance of equipment such as a shield machine, a storage battery car, a steel rail and the like are enhanced, the organization personnel in band of a project manager perform safety inspection every week, and the problems are found and corrected in time.

And fifthly, the whole process of the shield tunneling construction is strictly controlled, and engineering technicians correctly issue tunneling instructions for each shift and immediately track and adjust the tunneling instructions according to various exploration and measurement data information such as geological change, tunnel burial depth, ground load, surface subsidence, shield machine posture, cutter torque, jack thrust and the like.

Segment assembling operation: the assembled working face is hung with operation rules and striking warning boards. Strict rules of a person who stops the station within the rotation range of the weight lifting arm are strictly executed, and important inspection is carried out. Duct piece lighters need to strictly carry out the requirement that the assembly heads are screwed in place, check the condition of screw teeth of the duct piece lighters, supervises and urges the check, strictly controls the customs, strengthens education and makes the best of the intersection work.

And seventh, the battery locomotive achieves the purpose of fixing the locomotive, fixing the person, keeping the motorcycle on duty. The battery locomotive must limit the speed to run (< 10 km/h), before starting, the locomotive rings the horn, and the driver should concentrate on the thought and pay attention to the observation. And the speed of the subsequent trolley entering the shield machine is limited by 5 km/h. The speed change and the brake must be slow, so as to prevent the articles on the vehicle from moving and falling.

Environmental protection and energy saving measures:

the special staff is responsible for reporting detailed civilized construction management measures to supervision and approval before the project is started, and assigning the special staff to be responsible for daily management work of civilized construction.

Field management:

firstly, in a field construction area, a construction special enclosure which is uniformly required by an owner is adopted for sealing, and the height of the enclosure is not less than 2 m.

Secondly, slurry, waste soil, concrete and the like generated in the construction process are cleaned in time, the cleaning of the construction site is completed, and the appearance of the city are prevented from being influenced.

And materials on the construction site are stacked orderly and are stacked and discarded randomly, so that smooth traffic in the construction process is ensured.

And fourthly, in the construction process, the construction method strengthens communication with relevant units and departments and reduces construction influence together.

The process principle is as follows:

(1) according to the actual space condition on site, combining the design lengths of the shield machine and the trolley and the cooperative operation form of each equipment system, and performing repeated splitting and staged propulsion through a series of construction process optimization;

(2) by adopting a series of invention creation and equipment transformation, the problems of shield split starting pipeline extension and shield slag tapping are solved;

(3) the semi-ring originating form is adopted, so that the limitation of the shield muck and the vertical transportation space of the pipe piece is solved;

(4) aiming at a complex surrounding construction environment, the communication and coordination among surrounding units are actively enhanced, the cross construction influence is reduced, and the node construction period is ensured;

(5) aiming at the initial tunneling of the upper soft and lower hard layer, the construction parameters such as tunneling parameters, soil output, grouting amount and the like are optimized and construction monitoring is strengthened by detailed geological exploration and combination of theoretical foundation.

The foregoing shows and describes the general principles, essential features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are merely illustrative of the principles of the invention, but that various changes and modifications may be made without departing from the spirit and scope of the invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A split starting construction method for shield of a small clearance stratum with a soft upper part and a hard lower part is characterized by comprising a construction process flow and operation key points;

the construction process flow comprises the following steps:

reinforcing the stratum of the starting end;

installing an originating base;

the shield machine is put into a well and assembled;

starting tunneling and load debugging;

2. The split starting construction method for the shield of the small clearance and the upper soft and the lower hard stratum as claimed in claim 1, wherein the operation points comprise split starting operation points, semi-ring starting operation points, tunneling parameter control points of the upper soft and the lower hard stratum and split starting technical measures of the shield of the upper soft and the lower hard stratum.

3. The split starting construction method for the shield in the small clearance, soft upper layer and hard lower layer as claimed in claim 2, wherein the split starting operation key point comprises that the construction is carried out by adopting a gantry crane and small slag hopper unearthing mode in a tunneling section before the shield enters a soil body; and when the starting wellhead space is large, constructing by adopting a gantry crane and a large muck bucket unearthing mode.

4. The split starting construction method for the shield in the small clearance and upper soft and lower hard stratum as claimed in claim 2, wherein the semi-ring starting operation key points comprise a duct piece dismantling space, duct piece hoisting and negative ring duct piece reinforcement.

5. The split starting construction method for the shield of the small-clearance upper-soft lower-hard stratum as claimed in claim 2, wherein the main control points of the tunneling parameters of the upper-soft lower-hard stratum comprise geological exploration, development and control of tunneling parameters, soil output and synchronous grouting.

6. The split starting construction method for the shield of the small clearance and the upper soft and lower hard stratum as claimed in claim 2, wherein the split starting technical measures for the shield of the upper soft and lower hard stratum comprise a shield tunneling technical measure, a segment splicing technical measure, a wall back grouting technical measure and a monitoring and measuring technical measure.

7. The split starting construction method for the shield in the small clearance, upper soft and lower hard stratum as claimed in claim 2, wherein the operation key points further comprise quality control measures, and the quality control measures comprise segment entrance quality acceptance and segment stacking and transportation.

8. The split starting construction method for the shield in the small clearance, soft upper layer and hard lower layer as claimed in claim 2, wherein the operation key points further comprise safety control measures, and the safety control measures comprise personnel configuration, before-class speech, emergency drilling and safety inspection.

9. The split starting construction method for shield tunneling on small clearance, soft top and hard bottom stratum as claimed in claim 2, wherein the operation key points further comprise environmental protection and energy saving measures, and the environmental protection and energy saving measures comprise the responsibility of full-time personnel, the comprehensive development of the activities of establishing civilized construction sites and the field management.

10. The split starting construction method for the shield in the small-clearance upper-soft lower-hard stratum as claimed in claim 1, wherein the first distance is 16m/10 rings, the second distance is 9.6m/6 rings, the third distance is 32m/20 rings, and the fourth distance is 41.6m/26 rings.