阅读说明：本技术 下穿既有铁路双线隧道盖挖施工方法 (Under wear existing railway double track tunnel cover and cut construction method ) 是由 刘晓欢 路遥 张志恒 谢兴 王玉伟 高志平 高新刚 段英杰 武泽帆 李军 张永超 于 2019-08-14 设计创作，主要内容包括：本发明公开了一种下穿既有铁路双线隧道盖挖施工方法,包括如下步骤：(1)、钻孔桩施工：1.1、机械就位、护筒埋设,1.2、泥浆制备；(2)、土方施工：2.1、基坑开挖,2.2、护拱“土模”施工；(3)冠梁及护拱施工：3.1、施工准备,3.2、基槽开挖,3.3、钢筋绑扎,3.4、支模,3.5、砼浇筑；(4)、土方回填施工。本方法通过“土模”代替传统工艺中的“支架+模板”模式,并通过“冠梁+护拱”混凝土一次浇筑的工艺,有效减少基坑暴露时间,完善明挖隧道施工方案,快速、安全的完成盖挖护拱的施工,及时恢复既有铁路,减少既有铁路停运时间,节约施工成本。(The invention discloses existing railway double track tunnel cover and cut construction method is worn under one kind, include the following steps: (1), drilled pile construction: 1.1, mechanical in place, shield-tube embedment, 1.2, slurrying；(2), earthwork construction: 2.1, excavation of foundation pit, 2.2, shield arch " clay model " construction；(3) crown beam and shield arch construction: 3.1, preparation of construction, 3.2, foundation trench excavation, 3.3, reinforcing bar binding, 3.4, formwork, 3.5, concrete placings；(4), backfilling of earthwork is constructed.This method replaces " bracket+template " mode in traditional handicraft by " clay model ", and pass through the technique of " crown beam+shield arch " concrete one-time-concreting, effectively reduce foundation pit exposure duration, improve open trench tunnel arrangement and method for construction, quickly, safe completion lid digs the construction of shield arch, restore existing railway in time, reduce existing railway idle time, saves construction cost.)

1. wearing existing railway double track tunnel cover and cut construction method under one kind, characterized by the following steps:

(1), drilled pile construction

1.1, mechanical in place, shield-tube embedment

The smooth processing in construction site guarantees that smooth, compacting is answered in rotary drilling rig pedestal place, after surveying setting-out stake position determines, Four control stake positions are released using cross hairs, and carry out embedded casing on the basis of four control stakes；

1.2, slurrying

1.2.1, select bentonite to prepare mud, bentonite incorporation adjusted according to geological condition, the control of overall incorporation 5% ~ Between 12%；

1.2.2, mud match ratio

After bentonite, additive are marched into the arena, test mud is deployed with site operation water immediately, each material in match ratio is specified and uses Amount, and record in detail, it is determined by experiment final match ratio；

1.2.3, drilling machine it is in place

Drilling machine is rotary drilling rig, when drill bit align piles position central cross line, all data, that is, lockable, drilling machine in place after drill bit Center and pile center are to just accurately, and control errors are in 1cm；

1.2.4, drilling, pore-forming

Mud off is used in drilling construction；

1.2.5, pore-forming inspection, borehole cleaning

Borehole cleaning is carried out after pore-forming immediately, borehole cleaning uses reacting cycle displacement mud mode, and mud time swap is no less than 15min, In Mud index stops after reaching requirement in hole；

Mud index and bottom hole sediment reach acceptance criteria when changing slurry borehole cleaning, after removing mud displacement conduit, use ultrasonic wave Detector checks whether the aperture of pore-forming and gradient meet acceptance criteria, if exceeded, is according to circumstances handled, until reaching Acceptance criteria；

1.2.6, fabrication of reinforcing cage and lifting

Steel bar meter is constructed in strict accordance with design drawing, and main reinforcement uses overlap welding, and single-selded lap joint fusion length is 10d, Two-sided overlap welding fusion length is 5d, and overlapping regions carries out prebuckling, 3 ° of bending angle, guarantees the straight line transmitting of power in main reinforcement, Quality has to comply with design and code requirement, and 35d range nipple number must not exceed the 50% of reinforcing bar sum；Main reinforcement is adopted with stirrup Use spot welding；According to following provisions screwing steel bars cage in construction: first making the Reinforced Hoop of reinforcing bar, Reinforced Hoop is first according under design length Expect and bent on platform, after Reinforced Hoop completes, accurate setting-out goes out each main reinforcement of reinforcing bar on Reinforced Hoop Accurate location simultaneously makes a mark, and according to mark position, accurately welds each main reinforcement, tie hoop is wound in steel reinforcement cage main reinforcement On, stirrup and main reinforcement are pricked using side and are connected；

1.2.7, conduit installation

Catheter length is determined that conduit bottom is away from 250~400mm of bottom hole, and catheter tip is beyond ground by hole depth and workbench height Face, upper termination blanking funnel；

Concreting bracket section steel manufacture, is used to support suspention conduit, and coagulation soil hopper is placed on top；

1.2.8, filling concrete

1.2.8.1, pouring underwater concrete use vertical duct method, concrete use commerical ready-mixed concrete, and check mobility and The slump；

1.2.8.2, underwater concrete wants continuous placing, must not pause halfway, guarantees that concrete continuous enters hole, conduit is in concrete In buried depth control in 2 ~ 6m；

1.2.8.3, during casting concrete, the height of concrete surface is measured at any time, is computed correctly conduit Transducers Embedded in Concrete Depth, before pouring, according to practical pore-forming aperture situation, calculate concrete amount, concrete is disposably poured by conduit, Then it measures concrete surface and completes perfusion when concrete surface is more than design 0.3 ~ 0.5m of concrete surface, propose conduit, remove vertical The fixation of stanchion；

(2), earthwork construction

2.1, excavation of foundation pit

2.1.1, when excavation of foundation pit, design requirement 1:0.75 ~ 1:1 slope is pressed in the above earthwork of crown beam, and every layer of cutting depth control exists 3m sprays anchor in time after having dug；

2.1.2, when longitudinal slope is excavated, intercepting ditch or water blocking earth embankment should be set outside top of the slope；

2.1.3, after excavation of foundation pit, setting hole internal drainage ditch and sump；

2.1.4, when mechanical shoveling, hole bottom retains 200 ~ 300mm thick soil stratum and manually excavates leveling；

2.2, shield talent arch soil mould construction

2.2.1, technical staff measures technology by line style setting-out to scene, and to excavating-machine operator according to shield arch design radian It tells somebody what one's real intentions are；

2.2.2, crown beam and shield arch are constructed together

It protects after the completion of talent arch soil mould, construction cushion coat concrete is carried out using gunite concrete mode；

(3) crown beam and shield arch construction

3.1, preparation of construction

Before crown beam and shield arch construction, unwrapping wire is measured first, determines that the contour line of crown beam and shield arch, drilled pile will be cut Extra pile crown part；

3.2, foundation trench excavates

Based on crown beam and shield skewback slot are excavated with excavator, and foundation pit side opening wall reinforced concrete is manually excavated with pneumatic pick；

3.3, reinforcing bar is bound

Crown beam and shield arch reinforcing bar are processed by design requirement in fabricating yard blanking, transport to live binding, and when binding pays attention to bar spacing And array pitch, and reserved steel bar in stake is protruded into crown beam framework of steel reinforcement；

3.4, formwork

Crown beam and shield arch template use wooden model, and template wants smooth, and smears release agent, guarantees firm supporting；

3.5, concrete placings

By concrete mixing station centralizedly supply, concrete transport vehicle is transported to scene, is sent directly into template, shaken with plug-in type for crown beam and shield arch concrete Tamper is layered vibration compacting；

(4), backfilling of earthwork is constructed

4.1, backfill shield arch apply finish and concrete strength reach design strength after carry out；Arch backfill two sides symmetrically into Row, compaction in layers, every thickness degree are not more than 0.3m, and two sides backfill difference in height is not greater than 0.5m, after backfill is flushed with vault, Full paving is layered again to fill to designed elevation；When using machinery backfill, carried out after hand compaction filling height is greater than 1.0m or more；

4.2, it protects in backfilling process within the scope of dome portions 100cm and is filled out using electric tamper rammer；

4.3, foundation pit segmentation backfill joint part, fill slope scrapes out step, and step width is not less than 1.0m, is highly not more than 0.5m；Lap width when cal rolling is not less than 20cm, Chong Die between rammer and rammer when artificial rammer is filled out that bottom width is rammed not less than 1/3 Degree；

4.4, it backfills in roller compaction process, takes a sample to check and backfill compactness, foundation pit backfill grinding compacting degree should meet related code requirement.

Technical field

The invention belongs to tunnel construction fields, specially wear existing railway double track tunnel lid excavation construction side under one kind Method, suitable for wearing the construction of existing railway and road under highway, railway, municipal open trench tunnel.

Background technique

With the fast development of China's City Underground Transportation, three-dimensional hand over occurs for city open trench tunnel and existing railway and road The case where fork, is more and more, and how safely, quickly pass through existing road is the key points and difficulties in open trench tunnel construction.

Summary of the invention

It is an object of the present invention to provide existing railway double track tunnel cover and cut construction method is worn under one kind, it is perfect to form a whole set of Under wear existing railway double track tunnel lid excavation construction technique, by optimization each process linking, ensure that open-cut foundation ditch and shield arch apply Work safety.

The present invention is achieved by the following technical scheme:

Existing railway double track tunnel cover and cut construction method is worn under one kind, is included the following steps:

(1), drilled pile construction

1.1, mechanical in place, shield-tube embedment

The smooth processing in construction site guarantees that smooth, compacting is answered in rotary drilling rig pedestal place, after surveying setting-out stake position determines, Four control stake positions are released using cross hairs, and carry out embedded casing on the basis of four control stakes.

1.2, slurrying

1.2.1, select bentonite to prepare mud, bentonite incorporation adjusted according to geological condition, the control of overall incorporation 5% ~ Between 12%.

1.2.2, mud match ratio

After bentonite, additive are marched into the arena, test mud is deployed with site operation water immediately, each material in match ratio is specified and uses Amount, and record in detail, it is determined by experiment final match ratio.

1.2.3, drilling machine it is in place

Drilling machine is rotary drilling rig, when drill bit align piles position central cross line, all data, that is, lockable, drilling machine in place after drill bit Center and pile center are to just accurately, and control errors are in 1cm.

1.2.4, drilling, pore-forming

Mud off is used in drilling construction.

1.2.5, pore-forming inspection, borehole cleaning

Borehole cleaning is carried out after pore-forming immediately, borehole cleaning uses reacting cycle displacement mud mode, and mud time swap is no less than 15min, In Mud index stops after reaching requirement in hole；

Mud index and bottom hole sediment reach acceptance criteria when changing slurry borehole cleaning, after removing mud displacement conduit, use ultrasonic wave Detector checks whether the aperture of pore-forming and gradient meet acceptance criteria, if exceeded, is according to circumstances handled, until reaching Acceptance criteria.

1.2.6, fabrication of reinforcing cage and lifting

Steel bar meter is constructed in strict accordance with design drawing, and main reinforcement uses overlap welding, and single-selded lap joint fusion length is 10d, Two-sided overlap welding fusion length is 5d, and overlapping regions carries out prebuckling, 3 ° of bending angle, guarantees the straight line transmitting of power in main reinforcement, Quality has to comply with design and code requirement, and 35d range nipple number must not exceed the 50% of reinforcing bar sum；Main reinforcement is adopted with stirrup Use spot welding；According to following provisions screwing steel bars cage in construction: first making the Reinforced Hoop of reinforcing bar, Reinforced Hoop is first according under design length Expect and bent on platform, after Reinforced Hoop completes, accurate setting-out goes out each main reinforcement of reinforcing bar on Reinforced Hoop Accurate location simultaneously makes a mark, and according to mark position, accurately welds each main reinforcement, tie hoop is wound in steel reinforcement cage main reinforcement On, stirrup and main reinforcement are pricked using side and are connected.

1.2.7, conduit installation

Catheter length is determined that conduit bottom is away from 250~400mm of bottom hole, and catheter tip is beyond ground by hole depth and workbench height Face, upper termination blanking funnel；

Concreting bracket section steel manufacture, is used to support suspention conduit, and coagulation soil hopper is placed on top.

1.2.8, filling concrete

1.2.8.1, pouring underwater concrete uses vertical duct method, and concrete uses commerical ready-mixed concrete, transported by concrete tank When being transported to perfusion place, before filling concrete, it must check its opening quotation identification, check concrete grade, cement type, gather materials Whether specification and additive are consistent with the match ratio of concrete, and check mobility and the slump, when such as undesirable, answer Carry out it is secondary mix and stir, when still undesirable, must not use.

1.2.8.2, underwater concrete wants continuous placing, must not pause halfway, guarantees that concrete continuous enters hole, conduit is mixed Buried depth in solidifying soil is controlled in 2 ~ 6m.

1.2.8.3, during casting concrete, the height of concrete surface is measured at any time, and it is mixed to be computed correctly conduit embedment The depth for coagulating soil before pouring, according to practical pore-forming aperture situation, calculates concrete amount, concrete is disposable by conduit It pours into, then measures concrete surface when concrete surface is more than design 0.3 ~ 0.5m of concrete surface with lining rope and complete perfusion, propose Conduit removes the fixation of stand column pile.

(2), earthwork construction

2.1, excavation of foundation pit

2.1.1, when excavation of foundation pit, design requirement 1:0.75 ~ 1:1 slope is pressed in the above earthwork of crown beam, and every layer of cutting depth control is 3 Rice sprays anchor in time after having dug.

2.1.2, when longitudinal slope is excavated, intercepting ditch or water blocking earth embankment should be set outside top of the slope.

2.1.3, after excavation of foundation pit, hole internal drainage ditch and sump should be set, prevent hole bottom ponding.

2.1.4, when mechanical shoveling, hole bottom retains 200 ~ 300mm thick soil stratum and manually excavates leveling, prevents hole subsoil from disturbing It is dynamic.

2.2, shield arch " clay model " construction

2.2.1, technical staff measures technology by line style setting-out to scene, and to excavating-machine operator according to shield arch design radian It tells somebody what one's real intentions are.

2.2.2, crown beam and shield arch are constructed together

After the completion of shield arch " clay model ", construction cushion coat concrete is carried out using gunite concrete mode.

(3) crown beam and shield arch construction

3.1, preparation of construction

Before crown beam and shield arch construction, unwrapping wire is measured first, determines that the contour line of crown beam and shield arch, drilled pile will be cut Extra pile crown part.

3.2, foundation trench excavates

Based on crown beam and shield skewback slot are excavated with excavator, and foundation pit side opening wall reinforced concrete is manually excavated with pneumatic pick.

3.3, reinforcing bar is bound

Crown beam and shield arch reinforcing bar are processed by design requirement in fabricating yard blanking, transport to live binding, and when binding pays attention to bar spacing And array pitch, and reserved steel bar in stake is protruded into crown beam framework of steel reinforcement.

3.4, formwork

Crown beam and shield arch template use wooden model, and template wants smooth, and smears release agent, guarantees firm supporting.

3.5, concrete placings

By concrete mixing station centralizedly supply, concrete transport vehicle is transported to scene, is sent directly into template, shaken with plug-in type for crown beam and shield arch concrete Tamper is layered vibration compacting.

(4), backfilling of earthwork is constructed

4.1, backfill shield arch apply finish and concrete strength reach design strength after carry out；Arch backfill two sides symmetrically into Row, compaction in layers, every thickness degree are not more than 0.3m, and two sides backfill difference in height is not greater than 0.5m, after backfill is flushed with vault, Full paving is layered again to fill to designed elevation；When using machinery backfill, it is laggard 1.0m or more should to be greater than in hand compaction filling height Row.

4.2, it protects in backfilling process within the scope of dome portions 100cm and is filled out using electric tamper rammer.

4.3, foundation pit segmentation backfill joint part, fill slope scrapes out step, and step width is not less than 1.0m, is highly not more than 0.5m；Lap width when cal rolling is not less than 20cm, Chong Die between rammer and rammer when artificial rammer is filled out that bottom width is rammed not less than 1/3 Degree.

4.4, it backfills in roller compaction process, takes a sample to check and backfill compactness, foundation pit backfill grinding compacting degree should meet related rule Model requirement.

The method of the present invention has the advantages that

1, this method replaces " bracket+template " mode in traditional handicraft by " clay model ", and passes through " crown beam+shield arch " concrete The technique of one-time-concreting effectively reduces foundation pit exposure duration, improves open trench tunnel arrangement and method for construction, completion lid digging quickly, safe The construction for protecting arch restores existing railway in time, reduces existing railway idle time, saves construction cost.

2, this method ensure that the safety and stability in surrounding house, open trench tunnel foundation pit in the construction process, efficient, quick, The construction for completing open trench tunnel of safety, has fulfiled the recovery time of existing heavy-duty machine line ahead of schedule, reduces and produces to heavy-duty machine factory Influence, while in work progress, substantially without fugitive dust, sewage discharge is few at scene, and noise emission meets relevant laws and regulations regulation, obtains Good social benefit.

3, this method is with strong points, easy to operate, is easy to operating personnel's grasp.

The method of the present invention design rationally, is successfully applied to the newly-built southwestern loop wire Eastern Jin Dynasty tunnel open excavation section work of Taiyuan railway terminal Journey, economical, societal benefits are obvious, have good promotion and application value.

Detailed description of the invention

Fig. 1 shows process flow chart of the invention.

Fig. 2 indicates Construction technology of bored pile flow chart.

Specific embodiment

Below for wearing existing heavy-duty machine line construction under Eastern Jin Dynasty's tunnel open excavation engineering, introduces and wear existing railway under open trench tunnel The construction method that double track tunnel lid is dug.

Existing railway double track tunnel cover and cut construction method is worn under one kind, is included the following steps:

1, drilled pile construction

1.1, mechanical in place, shield-tube embedment

The smooth processing in construction site guarantees that smooth, compacting is answered in rotary drilling rig pedestal place, the drilling machine in drilling process is avoided to generate Depression.By surveying setting-out stake position determine after, using cross hairs release four control stake positions, and on the basis of four control stakes into The embedded casing of row.

1.2, slurrying

1.2.1, high-quality bentonite is selected to prepare mud.General bentonitic incorporation is 8%, that is to say, that is mixed in every 100L water Enter 8kg bentonite, bentonite incorporation can be adjusted according to geological condition, overall incorporation is generally between 5% ~ 12%.

1.2.2, mud match ratio

After bentonite, additive are marched into the arena, test mud is deployed with site operation water immediately, each material in match ratio is specified and uses Amount, and record in detail.It is determined by experiment final match ratio.

1.2.3, drilling machine it is in place

Drilling machine is rotary drilling rig, using hydraulic crawler stretch chassis, the foldable brill mast of automatic lifting, telescopic drill rod, have Verticality automatic detection and adjustment, hole depth digital-scroll technique etc., complete machine manipulation generally use Hydraulic guide control, load sensing, have Operate the features such as light, comfortable.Major and minor two elevators are applicable to the needs of a variety of situations in building site.When in drill bit align piles position When crux of heart line, all data, that is, lockable does not need to adjust again.Rear bit central and pile center's reply are positive quasi- in place for drilling machine Really, control errors are in 1cm.Organisation specific vehicle clears boring mud during drilled pile construction, keeps construction site neatly unimpeded.

1.2.4, drilling, pore-forming

Mud off is used in drilling construction.

1.2.5, pore-forming inspection, borehole cleaning

Borehole cleaning is carried out after pore-forming immediately, borehole cleaning uses reacting cycle displacement mud mode, and mud time swap is no less than 15min, In Mud index can stop after reaching requirement in hole.Sediment thickness is measured after borehole cleaning in time, walks process under positive tissue.

Mud index and bottom hole sediment reach acceptance criteria when changing slurry borehole cleaning, after removing mud displacement conduit, with surpassing Sonic wave detector checks whether the aperture of pore-forming and gradient meet acceptance criteria, if exceeded, is according to circumstances handled, until Reach acceptance criteria.

1.2.6, fabrication of reinforcing cage and lifting

Steel bar meter is constructed in strict accordance with design drawing, and the main reinforcement of steel reinforcement cage is HRB400 φ 25mm, is reinforced stirrup and is HRB400 φ 20mm, spiral bar are HPB300 φ 10mm.Main reinforcement uses overlap welding, and single-selded lap joint fusion length is 10d, two-sided Overlap welding fusion length is 5d, and overlapping regions needs prebuckling, 3 ° of bending angle, guarantees the straight line transmitting of power in main reinforcement, quality Design and code requirement are had to comply with, 35d range nipple number must not exceed the 50% of reinforcing bar sum.Reinforcement stirrup is HRB400C [email protected], main reinforcement and stirrup use spot welding, according to following provisions screwing steel bars cage in construction: the Reinforced Hoop of reinforcing bar is first made, Reinforced Hoop is first bent according to design length blanking and on special platform, quasi- on Reinforced Hoop after Reinforced Hoop completes True setting-out goes out the accurate location of each main reinforcement of reinforcing bar and makes a mark, and according to mark position, accurately welds each main reinforcement. Tie hoop is wound in steel reinforcement cage main reinforcement, and stirrup and main reinforcement can be used side and prick connection.

1.2.7, conduit installation

Catheter length is determined that conduit bottom is away from 250 ~ 400mm of bottom hole, and catheter tip is beyond ground by hole depth and workbench height Face, upper end are convenient for connecing blanking funnel.Pipe joint ring flange adds taper loop, and coxopodite conduit lower end must not have ring flange.Using Spiral screw thread type joint, if locking device.

Concreting bracket section steel manufacture, is used to support suspention conduit, and coagulation soil hopper is placed on top.Conduit installation The space of 250 ~ 400mm is arranged away from bottom hole at its bottom afterwards.

1.2.8, filling concrete

1.2.8.1, pouring underwater concrete uses vertical duct method, and concrete uses commerical ready-mixed concrete, transported by concrete tank When being transported to perfusion place, before filling concrete, it must check its opening quotation identification, check concrete grade (C30), cement product Whether kind, specification of gathering materials and additive are consistent with the match ratio of concrete, and check mobility and the slump, do not meet such as and want When asking, should carry out it is secondary mix and stir, when still undesirable, must not use.

1.2.8.2, underwater concrete wants continuous placing, must not pause halfway, guarantees that concrete continuous enters hole, as centre needs Conduit is removed, shortens the break time for removing conduit as far as possible.Buried depth of the conduit in concrete is preferably controlled in 2 ~ 6m.

1.2.8.3, during casting concrete, the height of concrete surface is measured at any time, and it is mixed to be computed correctly conduit embedment The depth for coagulating soil, before pouring, according to practical pore-forming aperture situation, amount of concrete need to be used by calculating, and consider certain reaming system Number considers the amount of concrete of superfilled 0.3 ~ 0.5m.Concrete is disposably poured by conduit, then measures concrete with lining rope Face, when concrete surface is more than design 0.3 ~ 0.5m of concrete surface, achievable perfusion proposes conduit, removes the fixation of stand column pile.Such as Fruit measures concrete surface and does not reach requirement, and need to continue casting concrete, until concrete surface reaches the above 0.5m in design face and is Only.

2, earthwork construction

Excavation of foundation pit follows the principle of " excavating after from top to bottom, vertical layered, longitudinal divisions, in time support, net spray concrete ", each Working face stage excavation from top to bottom.

2.1, excavation of foundation pit principle

2.1.1, excavation is to guarantee construction and ambient enviroment safety and node duration as principle.The sequence of earth excavation Method must be consistent with design conditions, and follows " vertical layered, horizontal fragmentation, symmetrical, balance, Rapid Excavation, quickly branch Support, fluting support, first support and dig afterwards, forbid to backbreak, ensure rapid construction under the premise of engineering safety quality " principle, make full use of " tau-effect ", Reducing distortion amount.

2.1.2, when excavation of foundation pit, design requirement 1:0.75 ~ 1:1 slope is pressed in the above earthwork of crown beam.Every layer of cutting depth control System sprays anchor at 3 meters in time after having dug.Forbid under a working condition, it is primary to excavate on earth.Spoir is stacked should be far from foundation pit top Other than 20 meters of sideline.

2.1.3, when longitudinal slope is excavated, intercepting ditch or water blocking earth embankment should be set outside top of the slope, prevent surface water from washing away slope It drains and flows back in infiltration hole again outside face and foundation pit.

2.1.4, after excavation of foundation pit, hole internal drainage ditch and sump should be set in time, prevent hole bottom ponding.

2.1.5, when mechanical shoveling, hole bottom should retain 200 ~ 300mm thick soil stratum and manually excavate leveling, prevent hole subsoil from disturbing It is dynamic.Digging machine and vehicle forbid collision to support, and bracing members top surface forbids to stack sundries.

2.2, shield arch " clay model " construction

2.2.1, technical staff measures technology by line style setting-out to scene, and to excavating-machine operator according to shield arch design radian It tells somebody what one's real intentions are.By field investigation, if crown beam and the separately construction of shield arch, it is contemplated that the pre-buried and crown beam concrete curing of shield arch reinforcing bar Deng, the construction period is longer, so determine crown beam and shield arch construct together.

2.2.2, after the completion of shield arch " clay model ", construction cushion coat concrete, it is contemplated that shield curved arch is smaller, is poured using tradition Concrete mode, blinding concrete thickness cannot be guaranteed well by protecting at the 1/4 of arch, determine to carry out using gunite concrete mode Blinding concrete construction.After the completion of blinding concrete construction, at later period cubic metre of earth and main body construction, blinding concrete is easy and shield Encircle concrete adhesion, the vibration when vibration or top train when construction in later period pass through be easy to cause part blinding concrete block to fall It falls, causes the hidden danger for injuring construction personnel by a crashing object, determine to be laid with one layer of plastic cloth between blinding concrete and shield arch concrete, make bed course Concrete is removed well with shield arch concrete, is eliminated safe hidden trouble.

3, crown beam and shield arch construction

3.1, preparation of construction

Before crown beam and shield arch construction, unwrapping wire is measured first, determines that the contour line of crown beam and shield arch, drilled pile will be cut Extra pile crown part.And carry out construction equipment outfit and personnel placement.

3.2, foundation trench excavates

Based on crown beam and shield skewback slot are excavated with excavator, and foundation pit side opening wall reinforced concrete is manually excavated with pneumatic pick.Excavate shield Various monitoring elements and reserving rib that protection is embedded in pile body are paid attention to when wall.

3.3, reinforcing bar is bound

Crown beam and shield arch reinforcing bar are processed by design requirement in fabricating yard blanking, and hand fit's truck is transported to live binding, tied up Bar spacing and array pitch are paid attention to when bundle, and reserved steel bar in stake is protruded into crown beam framework of steel reinforcement.

3.4, formwork

Crown beam and shield arch template use wooden model, and template wants smooth, and smears release agent, guarantees firm supporting.

3.5, concrete placings

By concrete mixing station centralizedly supply, concrete transport vehicle is transported to scene, is sent directly into template, shaken with plug-in type for crown beam and shield arch concrete Tamper is layered vibration compacting.Timely sprinkling maintenance is wanted after the completion of concreting.

4, backfilling of earthwork is constructed

4.1, backfill shield arch apply finish and concrete strength reach design strength after carry out.Arch backfill answer two sides symmetrically into Row, compaction in layers, every thickness degree are not more than 0.3m, and two sides backfill difference in height is not greater than 0.5m, after backfill is flushed with vault, Full paving is layered again to fill to designed elevation.When using machinery backfill, it is laggard 1.0m or more should to be greater than in hand compaction filling height Row.

4.2, mechanical in backfilling process or equipment must not crash feature, the electronic ramming of use in shield dome portions 100cm Machine rammer is filled out.

4.3, foundation pit segmentation backfill joint part, fill slope scrapes out step, and step width is not less than 1.0m, is highly not more than 0.5m.Lap width when cal rolling is not less than 20cm, Chong Die between rammer and rammer when artificial rammer is filled out that bottom width is rammed not less than 1/3 Degree.

4.4, it backfills in roller compaction process, takes a sample to check and backfill compactness, foundation pit backfill grinding compacting degree should meet related rule Model requirement.

4.5, when backfilling in rainy season, fine day is caught, is concentrated strength on, section construction, process is compact, takes, transports, filling out, putting down, pressing respectively Link closely follows operation.

This construction method is applied to wear existing heavy-duty machine line, this section of narrow field, existing heavy-duty machine line under Eastern Jin Dynasty's tunnel open excavation section Idle time is short, and the duration is nervous, and close to the village Lowland-swampLiu, surrounding house is more, and safety in production pressure is big.Existing railway two-wire is worn under Such construction method is used in tunnel lid excavation construction, reasonable arrangement tissue both ensure that the safety of construction personnel, machinery, property, And it is quick, it is economical and practical, it is at low cost, it ensure that construction quality, accelerate construction speed, complete the section within 20 days in advance than plan and apply Work obtains the approval and favorable comment of owner, management, achieves good social and economic benefit.

It should be noted last that the above examples are only used to illustrate the technical scheme of the present invention and are not limiting, although ginseng It is described in detail according to the embodiment of the present invention, those skilled in the art should understand that, to technical solution of the present invention It is modified or replaced equivalently, without departure from the spirit and scope of technical solution of the present invention, the present invention should all be covered by In the protection scope of claims.