CN109488347B - Excavation construction method for special stratum chamber - Google Patents

Excavation construction method for special stratum chamber Download PDF

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Publication number
CN109488347B
CN109488347B CN201811249505.6A CN201811249505A CN109488347B CN 109488347 B CN109488347 B CN 109488347B CN 201811249505 A CN201811249505 A CN 201811249505A CN 109488347 B CN109488347 B CN 109488347B
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chamber
supporting
construction
excavation
excavating
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CN109488347A (en
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梅树强
朱爱山
汪宏兵
周奎
陈春和
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Zhejiang Tunnel Engineering Group Co ltd
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Zhejiang Tunnel Engineering Group Co ltd
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    • EFIXED CONSTRUCTIONS
    • E21EARTH DRILLING; MINING
    • E21DSHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
    • E21D13/00Large underground chambers; Methods or apparatus for making them
    • EFIXED CONSTRUCTIONS
    • E21EARTH DRILLING; MINING
    • E21DSHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
    • E21D11/00Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling

Abstract

The invention relates to the field of chamber excavation, in particular to an excavation construction method for a chamber with a special stratum, which comprises the following construction steps: firstly, preparing construction equipment and personnel allocation, and performing measurement lofting on a construction area; step two, excavating and supporting the small chamber: adopting blasting or a heading machine to excavate, timely deslagging, and timely supporting by adopting a steel arch frame and an anchor net after deslagging, wherein the process of each cycle is 0.5-0.75 m, and excavating and supporting the upper part of the middle pilot tunnel by adopting a third step: step four, reversely expanding and digging the upper step of the big chamber; step five, excavating and supporting steps in the large chamber: sixthly, excavating and supporting a lower step (inverted arch) of the large chamber; and seventhly, lining the inverted arch of the large chamber and backfilling. The excavation method has the advantages of reliable excavation, small engineering quantity and the like.

Description

Excavation construction method for special stratum chamber
Technical Field
The invention relates to the field of civil air defense engineering, in particular to an excavation construction method for a special stratum chamber.
Background
In the excavation supporting process of a hall pointed by a civil air defense command, the basic design type is that a small channel chamber and a large command hall chamber are intersected in a cross shape, wherein the command hall is required to be arranged on the channel due to the large section design. In the process of expanding, digging and supporting from the small channel chamber to the big command hall chamber and forming from the command hall reverse expanding and digging to intersect with the small channel chamber, under special geological conditions, once the construction method is improper, the situation of incontrollable collapse and the like is easily caused. The company continuously summarizes results due to long-term construction of civil air defense pit tunnel engineering, and finally forms a new method for instructing the excavation support of a hall under special geological conditions, namely a special stratum large-span small chamber excavation construction method.
Disclosure of Invention
The invention provides an excavation construction method for a special stratum chamber, aiming at the defects of infirm excavation support, easy collapse, large engineering quantity and the like in the prior art.
In order to solve the technical problem, the invention is solved by the following technical scheme:
an excavation construction method for a special stratum chamber comprises the following construction steps:
firstly, preparing construction equipment and personnel allocation, and performing measurement lofting on a construction area;
step two, excavating and supporting the small chamber: excavating by adopting a blasting or tunneling machine, timely deslagging, wherein the progress of each cycle is 0.5-0.75 m, after deslagging is finished, timely supporting by adopting a steel arch frame and an anchor net,
step three, excavating and supporting the middle pilot tunnel to the top of the tunnel: before the inlet end of the pilot tunnel is excavated, firstly, paying off according to the measurement of an excavation contour line, then, erecting an advance anchor rod or an advance small guide pipe along the excavation contour line for grouting, cutting and dismantling the small chamber supporting structure along the excavation line, and then, blasting the inlet end of the pilot tunnel in excavation; excavating and supporting the middle pilot tunnel along an upward inclination angle of 13-15 degrees;
step four, reversely expanding and digging the upper step of the big chamber: after the middle pilot tunnel is excavated and supported to the far-end wall of the large chamber, the left side and the right side of the middle pilot tunnel are staggered for reversely expanding and excavating and supporting the upper step of the large chamber, and two sides of the upper step are supported and supported by adopting I-shaped steel support frames combined with anchor rods or anchor backing plates;
step five, excavating and supporting steps in the large chamber: supporting the steps in the large underground chamber, wherein the left side and the right side of the large underground chamber are staggered front and back during excavation and supporting, the step is arranged along a zigzag path, the excavation and supporting at one time cannot exceed 2 steel arch frames, excessive settlement deformation is prevented, I-shaped steel is supported in place in time after excavation, the bottom feet cannot be emptied, after the arch frames are supported, foot-contracting anchor rods are immediately arranged, the anchor rods and the steel arch frames are welded firmly, and then concrete is sprayed by hanging nets;
step six, excavating and supporting a lower step (inverted arch) of the large chamber: excavating and supporting the middle step to the far end wall of the large chamber, and excavating and supporting the lower step reversely;
and seventhly, lining the inverted arch of the large chamber and backfilling.
Preferably, the step one comprises the following steps:
(1) organizing personnel and equipment to enter a field, and completing facilities such as water and electricity supply, ventilation, power wind, drainage, road traffic, office and living rooms, warehouses, fire fighting, safety and the like before construction;
(2) compiling a special construction scheme and organizing expert argumentation according to the design file;
(3) carrying out detailed construction technology and safe bottom-crossing on managers and construction teams;
(4) organizing construction facilities and equipment to enter a field, and completing all materials and machines to meet the requirements of site construction conditions;
measuring and lofting: and determining the size of each circular excavation and support by using a total station, and making on-site safety protection, illumination, ventilation, drainage and warning signs.
Preferably, when the geology is the geology of weak surrounding rock, the blasting in the step one is carried out in a mode of combining smooth blasting and loose blasting, and the slag tapping is carried out by matching a loader with a dump truck or a tractor.
Preferably, after the small chamber reaches the side line of the designed side wall of the large chamber, the large chamber is continuously excavated forward 1/2 distance of the span of the large chamber to advance to the footage and the support is completed.
Preferably, in the fourth step, the upper end face of the upper step is kept flat in the reverse excavation process, and after the upper step is excavated to the small chamber part, the middle part of the small chamber I-steel and the net-jet supporting structure is only removed at most.
Preferably, the step four and the step five are also followed by the step of lengthening and supporting the arches at two sides of the upper step of the large chamber in the range of the small chamber to the steel arch of the reinforcement section of the small chamber for welding and fixing.
By adopting the technical scheme, the invention has the following beneficial effects:
the construction method follows the principle of 'short footage, weak excavation (blasting), strong support, early sealing, fast inverted arch and frequent measurement', a small chamber is firstly excavated to support and pass through a large chamber, then a guide tunnel in the large chamber is excavated from the side wall of the small chamber to advance to the top of the large chamber, then the large chamber is gradually expanded and excavated, and the T-shaped opening large chamber and small chamber interface is excavated and supported in place by adopting a beam-stealing and column-changing mode.
Compared with the traditional large-span small chamber excavation method, the technical scheme provided by the invention has the following advantages:
(1) the small chamber is excavated in advance and supported to penetrate through the large chamber, so that the secondary excavation of the small chamber on the other side is avoided, and the cutting and disturbance of the supporting structure of the large chamber are avoided. On one hand, the method is beneficial to the stability of surrounding rock and a supporting structure, on the other hand, the supporting engineering quantity is saved, and the manufacturing cost is reduced;
(2) when the upper step of the large chamber is reversely expanded and excavated, the original small chamber supporting structure at the T-shaped opening is locally and gradually detached from the middle, so that the stability of the small chamber supporting structures at two sides close to the intersection is kept, surrounding rocks above the T-shaped opening are strongly supported, and the surrounding rocks in front of the end wall of the large chamber close to the side of the T-shaped opening are not in a cantilever state.
(3) In the process of enlarging and digging the large underground chamber, two zigzag paths are adopted in the digging and supporting sequence along the axis of the large underground chamber, namely, an upper step, a middle step and a lower step walk along a vertical surface and the zigzag paths are dug on the plane in a left-right subsection mode, so that the stable stress of the finished supporting structure is kept to the maximum extent, and the steel arch frame is prevented from generating larger settlement deformation; meanwhile, the damage of a large-scale machine to an inverted arch supporting structure caused by rolling and walking on the inverted arch which is already supported in the initial stage is avoided, parallel construction is facilitated, and lining inverted arch construction is started as early as possible.
Drawings
FIG. 1 is a diagram of the construction steps of the overall scheme;
figure 2 is a sectional construction schematic view of the overall scheme,
FIG. 3 is a schematic view of the construction of a large chamber in zones;
fig. 4 is a construction template diagram of a large chamber.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples.
As shown in fig. 1 to 3, the construction method provided by this embodiment can be applied to various "cross-shaped small-size enlarged underground space exploitation constructions such as underground civil air defense engineering, national air defense engineering, mines, underground oil depots, grain depots, and the like.
As shown in fig. 2 and 3, the overall excavation sequence is: the small chamber-the middle pilot tunnel-A-B-C-D, wherein the BCD should be excavated in a left-right staggered mode.
The whole construction method has the process principle that: and (3) adopting a small chamber to firstly excavate and support the small chamber to pass through the large chamber by a distance exceeding 1/2 large chamber span distance, and carrying out combined support of a steel arch frame and anchor net spraying on the small chambers on two sides of the T-shaped port to form a stable reinforced section.
When the large chamber is excavated, firstly, the window is broken through a lower pilot tunnel from the side wall of the small chamber, then the middle pilot tunnel is excavated to the top of the large chamber by adopting an upper slope angle of 15 degrees, and then the upper pilot tunnel is excavated to the far end wall of the large chamber.
After the excavation of the upper pilot tunnel is finished, excavating the upper steps in place from the source end wall of the large chamber to two sides in sequence to form an upper step excavation working surface; and then, reversely excavating the upper step to the position near the T-shaped opening, wherein the steel arch of the upper step of the large chamber is tightly welded with the steel arch support structure of the reinforced section of the small chamber in each circulating support.
After the upper step of the large chamber is reversely expanded to the near-end wall, the middle step is excavated and supported to the far-end wall of the large chamber from the T-shaped opening by adopting a 'T' -shaped route.
After the excavation and support of the middle step are finished, excavating a lower step from the far end wall of the large chamber, and excavating and supporting simultaneously; the lower step excavation and support still adopt a zigzag path, and finally the inverted arch of the large chamber is closed into a ring until reaching the near-end wall of the large chamber with a T-shaped opening. And finishing excavation and primary support of the large underground chamber.
Because surrounding rocks are weak under special geological conditions, inverted arch lining reinforced concrete and backfilling must be constructed immediately after the primary support of an inverted arch of a large chamber is finished, so that potential safety hazards caused by overlarge hogging moment of the inverted arch are avoided, and the self weights of the inverted arch lining reinforced concrete and the backfilling concrete play a role in balancing.
The specific construction method comprises the following steps:
1. the method comprises the following construction steps:
firstly, preparing construction equipment and personnel allocation, and performing measurement lofting on a construction area;
step two, excavating and supporting the small chamber: excavating by adopting a blasting or tunneling machine, timely deslagging, wherein the progress of each cycle is 0.5-0.75 m, after deslagging is finished, timely supporting by adopting a steel arch frame and an anchor net,
step three, excavating and supporting the middle pilot tunnel to the top of the tunnel: before the inlet end of the pilot tunnel is excavated, firstly, paying off according to the measurement of an excavation contour line, then, erecting an advance anchor rod or an advance small guide pipe along the excavation contour line for grouting, cutting and dismantling the small chamber supporting structure along the excavation line, and then, blasting the inlet end of the pilot tunnel in excavation; excavating and supporting the middle pilot tunnel along an upward inclination angle of 13-15 degrees; and after the height of the vault of the large chamber is reached, the top support is changed into the support according to the support structure of the large chamber. In order to prevent the arch crown steel arch frame from sinking, temporary I-steel supporting legs are adopted to support the arch crown I-steel at the position of the side wall of the pilot tunnel.
Step four, reversely expanding and digging the upper step of the big chamber: after the middle pilot tunnel is excavated and supported to the far-end wall of the large chamber, the left side and the right side of the middle pilot tunnel are staggered for reversely expanding and excavating and supporting the upper step of the large chamber, and two sides of the upper step are supported and supported by adopting I-shaped steel support frames combined with anchor rods or anchor backing plates; but the construction is guided according to the principles of short footage, weak excavation (blasting), duty measurement and strong support. Under the geological condition of weak surrounding rock, the control of the excavation footage of each cycle is very critical, and meanwhile, the smoothness of the tunnel face is also controlled, so that the tunnel face cannot be dug into a pot bottom shape. The vault settlement observation and the arch springing convergence observation are the guarantee of safe construction. After the upper step is excavated to the small chamber part, on one hand, the I-shaped steel and the net-jet supporting structure of the small chamber are not needed to be removed urgently, and even if the I-shaped steel and the net-jet supporting structure are removed, only the middle part is removed, so that the supporting effect of the strong support of the small chamber on the face of the upper step of the large chamber is ensured, and the phenomenon of 'immortal soil' on the face is prevented. Before excavating the steps in the big chamber, the arches at the two sides of the upper step of the big chamber in the range of the small chamber are necessarily lengthened and supported on the steel arch of the reinforcement section of the small chamber, and the steel arches are firmly welded.
Step five, excavating and supporting steps in the large chamber: supporting the steps in the large underground chamber, wherein the left side and the right side of the large underground chamber are staggered front and back during excavation and supporting, the step is arranged along a zigzag path, the excavation and supporting at one time cannot exceed 2 steel arch frames, excessive settlement deformation is prevented, I-shaped steel is supported in place in time after excavation, the bottom feet cannot be emptied, after the arch frames are supported, foot-contracting anchor rods are immediately arranged, the anchor rods and the steel arch frames are welded firmly, and then concrete is sprayed by hanging nets;
step six, excavating and supporting a lower step (inverted arch) of the large chamber: excavating and supporting the middle step to the far end wall of the large chamber, and excavating and supporting the lower step reversely; because the inverted arch is the last working procedure of excavation and support of the big chamber, the advantages of reverse expanding excavation and support are as follows: (1) the excavation and the supporting can be operated in parallel without mutual interference; (2) the inverted arch support structure is prevented from being rolled by an excavator, a loader and a large-sized vehicle, the integrity, the stability and the concrete strength of the support layer are damaged, and the inverted arch settlement deformation possibly caused by the mechanical weight is avoided; (3) the pollution to the finished inverted arch supporting layer is avoided, the quality of the finished product is protected, and the cost caused by cleaning pollutants is reduced.
And seventhly, lining the inverted arch of the large chamber and backfilling. After the excavation and supporting of the inverted arch of the large chamber are finished, the supporting layer structure is completely closed-loop, and a relatively complete supporting system is formed. However, under the condition of weak geology, a lining layer must be constructed in time to ensure the stability, safety and durability of the large chamber supporting structure. Because the stress of the inverted arch is a negative bending moment theoretically, under the geological condition of weak surrounding rock, once the inverted arch is uplifted and deformed, the integral instability of the upper supporting structure can be caused. Therefore, the method is particularly important for constructing an inverted arch lining and backfilling concrete in time and plays a role of 'counterweight'. And after the convergence and deformation observation of the upper supporting structure meets the requirements, manufacturing upper lining reinforced concrete.
The method comprises the following steps:
(1) organizing personnel and equipment to enter a field, and completing facilities such as water and electricity supply, ventilation, power wind, drainage, road traffic, office and living rooms, warehouses, fire fighting, safety and the like before construction;
(2) compiling a special construction scheme and organizing expert argumentation according to the design file;
(3) carrying out detailed construction technology and safe bottom-crossing on managers and construction teams;
(4) organizing construction facilities and equipment to enter a field, and completing all materials and machines to meet the requirements of site construction conditions;
measuring and lofting: and determining the size of each circular excavation and support by using a total station, and making on-site safety protection, illumination, ventilation, drainage and warning signs.
When the geology is the geology of weak surrounding rock, the blasting of step one adopts the mode that smooth surface blasting and not hard up blasting combine to go on, and the mucking adopts loader cooperation dump truck or tractor to carry out the mucking.
And step one, after the small chamber reaches the side wall boundary designed by the large chamber, continuously excavating the large chamber span 1/2 forward to advance to a footage and completing supporting.
And in the fourth step, the upper end surface of the upper step is kept flat in the reverse excavation process, and after the upper step is excavated to the small chamber part, the middle part of the I-shaped steel and the net-jet supporting structure of the small chamber is only removed at most.
In which the following materials and equipment were used in this example.
Main construction material table
Main construction machine equipment meter
Example 2
The difference between the embodiment and the embodiment 1 is that the embodiment also provides an overall construction scheme for the large chamber hall support.
Overall construction scheme for hall support
As shown in fig. 4, (1) a pair of integrated steel mould trolleys is designed in 6 m span of the main body. The trolley is composed of two parts, and each section can be butted when the length is 3 meters.
(2) A hall adopts a full-frame scaffold as an intermediate support, a wall 20# I-steel upright post and an arch part 12# I-steel arch form a support system main body, and joint stress is achieved through a screw jack. The arch part of the template adopts a shaped steel template and a side wall large steel-wood combined template.
(3) And H-shaped steel assembled die carriers for mining other sections and branch tunnels, arch part shaping steel templates and side wall bulk shaping steel templates.
(4) The molded concrete is commercial concrete.
2. Process requirements
The design requirements of the die carrier and the die plate are as follows:
correct size and mutual position;
sufficient strength, stiffness, stability (mainly bearing concrete weight and side pressure, construction load);
the structure is simple, the assembly and disassembly are convenient, and the binding and the installation of the steel bars are convenient;
the joint is tight, slurry leakage is avoided, and the surface flatness and the dislocation meet the requirements.
The method is economical and practical, high in utilization rate and maximized in turnover frequency.
3. Concrete construction scheme
(1) Construction sequence and mold splitting scheme
This scheme contains hall, 6 meters steel mould platform truck section, passageway section, vestibule, power station and a tunnel construction branch mould, and protection section, inclined shaft and shaft are independent template and put at last from inside to outside construction. The rest of the penetration is carried out in parallel.
Principle: the trenching and the undermining which can be inserted or completed simultaneously during the tunnel excavation can be completed as early as possible; and the integral pouring is fully considered when the engineering mouth part, the reservoir and the protection section are divided into the moulds.
Under the condition of ensuring the safety of blasting vibration, the repeated working surface (mainly branch holes and chambers) can be firstly developed when the construction is carried out;
in order to develop more work surfaces of the quilt, the smoothness of the main channel during the repeated construction is ensured, and meanwhile, a material transportation channel of later internal engineering is considered.
(2) Command hall template
Hall basic data to be restored:
-a clear span of 14.58 meters, a clear height of 11.19 meters, a total length of 43.9 meters;
-the wall is 6.6 meters high and the C35P8 concrete is 0.7 meters thick;
the arch height is 4.59 meters, and the top thickness is 0.6 meters;
-end wall concrete thickness 0.7 m;
the maximum top one-mould pour is expected to be 150 cubic metres.
The general idea is as follows:
the concrete wall and the arch are separately poured, and the pouring height of the wall is 6.25 m; the concrete is commercial concrete, and the concrete is poured by a delivery pump. And a steel plate waterstop is additionally arranged at the construction joint. Because the net section size of the cavern is large and the supporting difficulty of the template is large, the concrete pouring construction is carried out for three times, and the wall body is poured for the first time and is 145cm below the arching line; and pouring the arch concrete for the second time, and finally pouring the bottom plate concrete.
-the intersection is performed using a combination of a D-shaped mold and a hall mold;
pouring in five moulds, and manufacturing 13 trusses by using a mould frame; the trusses are connected by steel pipe fasteners.
A support system:
the full framing scaffold supports, the framing scaffold 800 is 915, and two ends of the full framing scaffold support are supported by the 20# I steel through screw jacks. The arch top is made of 12# I-steel, 16# channel steel and a frame pipe into an arch-shaped steel truss, the steel truss is divided into three sections and supported by full framing scaffold supports, and the height of the steel truss is adjusted by jacking screws.
Template:
the side wall of the compound concrete adopts a 915mm X600 mm X60 mm flat steel template, and the arch part adopts a 915mm X600 mm X60 mm fixed steel template.
(3) Main body trolley
The main body section is covered with C35P8 commercial concrete, the main body tunnels are divided into two types, one type of tunnels has the clear width of 6 meters and the height of 5.35 meters, the lining thickness is 350-500, and the construction length is about 171 meters; and planning to make 1 steel mould trolley with 6 meters length according to the segmentation. The specific construction process comprises the following steps:
-erecting mould
1) And after the rail clamping device is loosened, the steel mould trolley is in an idle running position, the central line of the trolley is consistent with the central line of the tunnel, and the deviation of the central line is less than 3 mm.
2) After the steel mould trolley is in place and braked, the rail clamping device is locked, and the vertical jack and the lateral jack are alternately started to enable the mould to stand at the designed position.
3) And (3) putting down the turnover template, screwing down the turnover template by using a connecting bolt, adjusting a footing jack to support the footing jack on the skid and the wood wedge, hanging the lateral jacks at the two ends of the trolley, checking whether the template has deviation at the moment, putting down the bracket, and adjusting by using a lateral jack.
The length of the lateral cylinder-free mechanical lock is adjusted, and the lock is locked by inserting the lock.
4) And hanging other lateral jacks, adjusting the length of the lateral cylinder-free mechanical lock, and inserting and locking.
5) And (5) supporting scaffold boards on two sides of the trolley, and tightening the template to collect the twisted part to obtain the butt bolt. The formwork is securely fixed in the design position by means of the diagonal braces.
6) And lowering the vertical jack to separate the bracket from the template.
7) And installing the plugging plate and the joint template. The plug board can be erected according to the excavation condition, when the lining thickness is within the range of 30-60 mm, only the inner side is erected by 30m, and when the lining thickness exceeds 60cm, the outer side can be increased by 30 cm. The plugging plate must be supported on the rock surface, and in order to prevent the U-shaped bolt from being stressed too much, the cantilever end of the plugging plate is supported tightly by an inclined strut.
8) And placing the footing form, wherein the lower part of the footing form is tightly attached to the outer side of the skid below the footing jack, and the upper part of the footing form is tightly attached to the side wall form by using a wooden support.
Adjustment in position
1) Front and back adjustment: is completed by a trolley running mechanism.
2) Left and right horizontal adjustment: adjusting the track position within 3cm by using a lateral jack, and adjusting the track position when the track position exceeds 3 cm.
3) Adjusting the height of the template: a monotonous vertical jack.
-pouring concrete
1) And (5) checking whether the plugging plate and the joint template are firmly installed.
2) Checking whether the working window of the perfusion part is closed.
3) Checking whether the delivery pipe joint is firm.
4) Before pouring concrete, the base must be washed clean by water, and the pouring is required to be carried out simultaneously on two sides, otherwise, the bias is caused to cause die running, and the two sides of the operation window of a pouring part must be plugged by pins.
5) The selection, mixing proportion, stirring, transportation, pouring and the like of the concrete material are carried out according to the concrete construction technical specification.
Removal of the form
1) When the lining concrete reaches the form removal strength, the plug plates and the telescopic rods of the joint form plates are firstly removed, then the lateral jacks and the mechanical locking bolts of the lateral jacks and the connection between the jacks and the form plates are removed, the vertical jacks and the brackets are descended, and the upper scaffold plate is put down to ensure that the trolley is completely separated from the form plates.
2) And moving the trolley to the section to be cast.
3) The vertical jack is used for synchronously jacking the bracket and connecting the bracket with the template, and the lateral jack is connected with the template.
4) Firstly, the arch crown template is folded with the butt bolts at the hinges and the turning hinges, the rest scaffold boards are put down, and the footing jack is loosened.
5) And then the two side templates are collected.
6) And synchronously lowering the vertical jack to ensure that the template is completely separated from the lining concrete.
7) And alternately starting the vertical jack and the lateral jack to draw the template into a running state.
8) And removing the concrete adhered to the surface of the template, and spraying a release agent.
(4) Main body simple assembled section steel mould frame
The main bodies of the simple assembled section steel die sets are two, and the clear width of 6 meters and the clear width of 7 meters are wide. It is suitable for branch holes, crossing and turning positions.
-wall form installation quality requirement
1) The template must be installed vertically, the elevation of the position is correct, and the two ends are in the same level.
2) The joints between the templates and the structure are tight and do not leak slurry.
3) The release agent must be brushed uniformly.
4) The door and window opening must be perpendicular squarely, and the position is accurate, and the door and window opening adopts the method of founding the mouth earlier, must fix firmly closely, must not shift and warp when concreting.
5) The bolts must be fastened, and the connection between the trusses is reliable.
6) Due to the flashing, the location of the closure plate must be against the rock.
-when removing the formwork
1) The collision of the wall body is strictly prohibited. The removed formwork is cleaned and maintained in time, and if deformation and cracking are found, the formwork is repaired in time.
2) The concrete strength is required to be higher than the allowable formwork-removing strength, and the concrete can be removed after the consent of a person in charge of engineering technology.
3) When the template is dismantled, an operator stands at a safe place to avoid unsafe accidents, the template, accessories, a bracket and the like are transported and stacked after the template is dismantled, the dismantled template and accessories are strictly forbidden to be thrown away, and the template and accessories are transferred by someone, stacked orderly according to a specified place, and the isolating agent is cleaned, maintained and coated in time for later use.
4) After the template is dismantled, to the edges and corners position of structure, in time protect to prevent the damage.
(5) Protective section mould frame
The protective segment is repeated as follows.
Firstly, integral pouring is required due to the sealing requirement;
secondly, because of protection requirements, the steel bars should be integrally manufactured and installed, and especially the horizontal steel bars are not allowed to be broken at construction joints.
And thirdly, the door frame wall reinforcing steel bars with shielding requirements in front of the vertical mold must be welded.
Fourthly, no construction joint is left horizontally, and a steel plate waterstop is needed to be adopted for the annular construction joint.
And fifthly, no waterproof layer is filled between the section of concrete and the tunnel.
Sixth, checking and calculating construction parameters of scaffold
Seventhly, form removal and maintenance
The form removal time is determined according to a test method, and is generally determined according to the steel form trolley and the form removal time with the span of 3 meters or less: 24 hours; removing the assembled template for 30 hours within 3-8 m; the arch crown demolition time of the hall is 4 days. And after the mold is removed, watering and curing are continuously carried out for 14 days.
In summary, the above-mentioned embodiments are only preferred embodiments of the present invention, and all equivalent changes and modifications made in the claims of the present invention should be covered by the claims of the present invention.

Claims (4)

1. An excavation construction method for a special stratum chamber is characterized in that: the method comprises the following construction steps:
firstly, preparing construction equipment and personnel allocation, and performing measurement lofting on a construction area;
step two, excavating and supporting the small chamber: excavating by adopting a blasting or tunneling machine, timely deslagging, wherein the progress of each cycle is 0.5-0.75 m, after deslagging is finished, timely supporting by adopting a steel arch frame and an anchor net,
step three, excavating and supporting the middle pilot tunnel to the top of the tunnel: before the inlet end of the pilot tunnel is excavated, firstly, paying off according to the measurement of an excavation contour line, then, erecting an advance anchor rod or an advance small guide pipe along the excavation contour line for grouting, cutting and dismantling the small chamber supporting structure along the excavation line, and then, blasting the inlet end of the pilot tunnel in excavation; excavating and supporting the middle pilot tunnel along an upward inclination angle of 13-15 degrees;
step four, reversely expanding and digging the upper step of the big chamber: after the middle pilot tunnel is excavated and supported to the far-end wall of the large chamber, the left side and the right side of the middle pilot tunnel are staggered for reversely expanding and excavating and supporting the upper step of the large chamber, and two sides of the upper step are supported and supported by adopting I-shaped steel support frames combined with anchor rods or anchor backing plates;
step five, excavating and supporting steps in the large chamber: supporting the steps in the large underground chamber, wherein the left side and the right side of the large underground chamber are staggered front and back during excavation and supporting, the step is arranged along a zigzag path, the excavation and supporting at one time cannot exceed 2 steel arch frames, excessive settlement deformation is prevented, I-shaped steel is supported in place in time after excavation, the bottom feet cannot be emptied, after the arch frames are supported, foot-contracting anchor rods are immediately arranged, the anchor rods and the steel arch frames are welded firmly, and then concrete is sprayed by hanging nets;
step six, excavating and supporting a lower step of the large chamber: excavating and supporting the middle step to the far end wall of the large chamber, and excavating and supporting the lower step reversely;
seventhly, lining and backfilling an inverted arch of the large chamber; when the geology is the geology of weak surrounding rock, the blasting in the step one is carried out in a mode of combining smooth blasting and loose blasting, and the slag is discharged by matching a loader with a dump truck or a tractor; and step one, after the small chamber reaches the side wall boundary designed by the large chamber, continuously excavating the large chamber span 1/2 forward to advance to a footage and completing supporting.
2. The excavation construction method for the special formation chamber as claimed in claim 1, wherein: the first step comprises the following steps:
(1) organizing personnel and equipment to enter a field, and completing hydropower supply, ventilation, power wind, drainage, road traffic, office and living rooms, warehouses, fire fighting and safety facilities before construction;
(2) compiling a special construction scheme and organizing expert argumentation according to the design file;
(3) carrying out detailed construction technology and safe bottom-crossing on managers and construction teams;
(4) organizing construction facilities and equipment to enter a field, and completing all materials and machines to meet the requirements of site construction conditions; measuring and lofting: and determining the size of each circular excavation and support by using a total station, and making on-site safety protection, illumination, ventilation, drainage and warning signs.
3. The excavation construction method for the special formation chamber as claimed in claim 1, wherein: and in the fourth step, the upper end surface of the upper step is kept flat in the reverse excavation process, and after the upper step is excavated to the small chamber part, the middle part of the I-shaped steel and the net-jet supporting structure of the small chamber is only removed at most.
4. The excavation construction method for the special formation chamber as claimed in claim 1, wherein: and step four and step five, the following step is added, and the arches on two sides of the upper step of the large chamber in the range of the small chamber are lengthened and supported to the steel arch of the reinforcement section of the small chamber to be welded and fixed.
CN201811249505.6A 2018-10-25 2018-10-25 Excavation construction method for special stratum chamber Active CN109488347B (en)

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CN101699030A (en) * 2009-11-20 2010-04-28 中冶集团华冶资源开发有限责任公司 Big underground chamber tunneling method
CN103234403B (en) * 2013-04-24 2014-11-19 中国科学院武汉岩土力学研究所 Static blasting construction method for highway tunnel
CN104948208B (en) * 2015-06-30 2017-07-28 昆明理工大学 It is a kind of that big constructing structure and method across cavern is laterally extended based on narrow and small underpass
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