CN114961336A - Protective demolition construction method for basement pile foundation next to existing subway line - Google Patents
Protective demolition construction method for basement pile foundation next to existing subway line Download PDFInfo
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- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04G—SCAFFOLDING; FORMS; SHUTTERING; BUILDING IMPLEMENTS OR AIDS, OR THEIR USE; HANDLING BUILDING MATERIALS ON THE SITE; REPAIRING, BREAKING-UP OR OTHER WORK ON EXISTING BUILDINGS
- E04G23/00—Working measures on existing buildings
- E04G23/08—Wrecking of buildings
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D17/00—Excavations; Bordering of excavations; Making embankments
- E02D17/18—Making embankments, e.g. dikes, dams
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D29/00—Independent underground or underwater structures; Retaining walls
- E02D29/045—Underground structures, e.g. tunnels or galleries, built in the open air or by methods involving disturbance of the ground surface all along the location line; Methods of making them
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D31/00—Protective arrangements for foundations or foundation structures; Ground foundation measures for protecting the soil or the subsoil water, e.g. preventing or counteracting oil pollution
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D9/00—Removing sheet piles bulkheads, piles, mould-pipes or other moulds or parts thereof
- E02D9/02—Removing sheet piles bulkheads, piles, mould-pipes or other moulds or parts thereof by withdrawing
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- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04B—GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
- E04B2/00—Walls, e.g. partitions, for buildings; Wall construction with regard to insulation; Connections specially adapted to walls
- E04B2/84—Walls made by casting, pouring, or tamping in situ
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- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04G—SCAFFOLDING; FORMS; SHUTTERING; BUILDING IMPLEMENTS OR AIDS, OR THEIR USE; HANDLING BUILDING MATERIALS ON THE SITE; REPAIRING, BREAKING-UP OR OTHER WORK ON EXISTING BUILDINGS
- E04G23/00—Working measures on existing buildings
- E04G23/06—Separating, lifting, removing of buildings; Making a new sub-structure
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D2250/00—Production methods
- E02D2250/0007—Production methods using a mold
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Abstract
The invention provides a protective demolition construction method for a basement pile foundation next to an existing subway line, which comprises the following steps: clearing the surface of the basement and forming construction hoisting holes; constructing a retaining wall at the intersection position of the underground structure to be removed and the side wall not to be removed, and constructing a buttress wall on the side wall of the basement to be removed; filling the underground structure chamber with backfill soil, and recharging water to ensure the balance of underground water levels inside and outside the basement; removing the top plate of the basement by cutting with a rope saw; hardening the area above the basement; a full-rotation full-casing drilling machine is adopted to remove a basement bottom plate and a bearing platform; removing the pile foundation; and backfilling plain concrete. The invention is used for quickly removing the pile body of the original structure in the foundation pit excavation, reduces the influence on the surrounding structures through the working procedures of separation, backfilling and the like, and realizes the purposes of high efficiency and safe construction.
Description
Technical Field
The invention relates to the field of building construction, in particular to a protective demolition construction method for a basement pile foundation next to an existing subway line.
Background
With the continuous promotion of urban construction progress in China, urban rail transit projects are continuously increased. When the situation of surrounding structures on a subway opening route is complex, particularly when the situation relates to the situation that a project needs to be reset on the basis of an original structure, "how to coordinate the dismantling of the structures, the relationship between the original structure and an existing subway operation line" and "how to maintain the stability of surrounding environment and underground water" become key points and difficulties in the dismantling of underground structures.
Although some researches on underground structure demolition cases are currently conducted at home and abroad, rapid and safe demolition and pile pulling close to basements of subway operation lines are rarely reported.
Disclosure of Invention
The invention aims to solve the technical problem of providing a protective demolition construction method of a basement pile foundation next to an existing subway line, which is used for quickly removing a pile body of an original structure in foundation pit excavation, reduces the influence on a surrounding structure through the working procedures of separation, backfilling and the like, and realizes efficient and safe construction.
The invention adopts the following technical scheme to solve the technical problems:
a protective dismantling construction method for a basement pile foundation next to an existing subway line comprises the following steps:
s1: clearing the surface of the basement and forming construction hoisting holes; here, the purpose of trompil is when making things convenient for the next construction buttress wall and backfill earthwork, and mechanical material transports and the construction.
S2: constructing a retaining wall at the intersection position of the underground structure to be removed and the side wall not to be removed, and constructing a buttress wall on the side wall of the basement to be removed; the construction retaining wall is used for separating an operation surface of an underground structure to be dismantled from a structure not to be dismantled, and effective separation between the working surface and an adjacent structure is realized; the basement side wall is reinforced to improve the deformation resistance of the side wall and ensure the stability of the surrounding stratum when the structure is dismantled.
S3: filling the underground structure chamber with backfill soil, and recharging water to ensure the balance of underground water levels inside and outside the basement; the purpose of basement backfilling is to ensure the soil pressure at two sides of the side wall to be balanced, and meanwhile, a bearing platform is broken by using a full-rotation casing drill under backfilled soil, so that the risk of water inrush from a bottom plate can be avoided, and the construction safety is improved; the irrigation operation is that after the pile foundation of the subsequent underground structure is pulled out, the basement overflows, and underground water flows into the underground structure, so that the water level around the underground structure is unbalanced and flows.
S4: and dismantling the top plate of the basement by using rope saw cutting.
S5: and (3) hardening the area above the basement, wherein the field hardening strength is required to ensure the safe construction of the crawler crane and the full-casing full-slewing drilling machine.
S6: a full-rotation full-casing drilling machine is adopted to remove a basement bottom plate and a bearing platform; here, adopt full-circle gyration full casing drill rig can wear through the concrete cushion cap in the basement backfill soil region fast for pile pulling speed reduces the time to the stratum disturbance, compares simultaneously in traditional breaking scheme and reduces the disturbance that breaks and cause existing subway line.
S7: removing the pile foundation;
s8: after the pile position is pulled out, plain concrete is backfilled in time; here, the purpose in concrete backfill stake hole is that the soil body is closely knit stable, also prevents deep confined water gushing risk simultaneously, protects the safety of peripheral subway operation line.
In a preferred embodiment of the present invention, in step S1, the original pavement layer of the surface layer of the underground structure is cleaned by using a excavator to clean the pavement; after the roof site is cleaned, working holes are formed in the corner sides of the roof for material transfer and backfilling operation; notice the roof and cut apart the size, use diamond rope cutting basement roof to carry out the trompil, rationally select hoist and mount machinery to hoist.
In a preferred embodiment of the present invention, in step S2, the height of the retaining wall is from the basement floor surface to the top floor surface, so as to separate the working surface of the underground structure to be removed from the non-removed structure, thereby achieving effective separation between the working surface and the adjacent structure.
As one preferable mode of the present invention, in step S2, the concrete construction process of the buttress wall is as follows:
(1) and (3) bar planting: chiseling the junctions of the buttress walls, the top plate, the side walls and the bottom plate, chiseling coarse aggregates, and purging; drilling and cleaning holes at positions needing bar planting by using a percussion drill, injecting glue into the holes after emptying, and immediately planting bars after injecting glue;
(2) binding steel bars: the reinforcing steel bars of the buttress wall enter the field and are bound;
(3) placing a template: after the steel bars are bound, installing a template, and reinforcing by adopting split bolts;
(4) pouring concrete: pouring concrete on the baffle;
(5) removing the mold and maintaining: and after the concrete reaches the specified strength, removing the formwork and maintaining.
Wherein, it should be noted that, the interface between the retaining wall and the top plate, side wall and bottom plate of the basement needs waterproof measures, including setting up the water-swelling water stop strip and galvanized steel edge water stop strip.
As one preferable mode of the present invention, in step S3, the excavator is suspended from the reserved hole on the top plate, and the excavator is backfilled to the bottom elevation of the top plate of the basement in layers; meanwhile, the water is reinjected into the underground chamber, so that the balance of the internal and external water levels of the underground structure is ensured; the backfilling is carried out by adopting an excavator and a bulldozer, the backfilled soil is paved in layers, and the thickness of each layer of paved soil is determined according to the soil quality, the compactness requirement and the performance of machines and tools.
As one preferable mode of the present invention, in step S4, an excavator is used to clean the original pavement layer of the basement surface layer, and then the impurities on the top of the top slab are cleaned to provide a cutting site; determining the cutting size of the top plate before cutting, cutting along the side line of the joint of the beam and the plate by using a wire saw, and cutting the cut plate into 2 small blocks; and then, determining a lifting appliance and a safe operation radius according to the lifting load to ensure the lifting safety, and cutting the top plate of the basement by using a diamond rope to open a hole.
As one preferable mode of the invention, in the step S5, the site is backfilled after the top plate is cut, and the earthwork is backfilled to the level of the site and compacted by a road roller; after backfilling is finished, hardening the area above the basement, wherein C30 concrete is adopted for hardening, heavy construction machinery is considered to be a crawler crane and a full-casing full-slewing drilling machine in the field, and the bearing capacity of the foundation is determined to reach 450kPa through tests.
As one of the preferable modes of the present invention, in step S6, the pile foundation to be pulled is measured and lofted, and the measurement point is re-checked and then measured to meet the bottom; secondly, placing a reaction plate according to the measuring point position to ensure that the roadbed is stressed uniformly, hoisting a full-rotation full-casing drilling machine to the reaction plate, checking the central point position of the pile after the drilling machine is in place, and checking whether the pile is empty; then preparing a first section of sleeve and welding a titanium alloy cutter head; finally, connecting the drilling machine with the power box and the operation room, hoisting a first section of casing after the drilling machine is initially leveled, adjusting the horizontal posture of the drilling machine and the vertical posture of the casing, and ensuring the verticality of the casing; in the construction process, the whole process monitoring and measuring are carried out on surrounding buildings and existing subway operation lines.
As one preferable mode of the present invention, in step S7, after the basement bottom plate and the bearing platform are removed by using the full-circle-of-revolution full-casing drilling machine, the pile pulling device is operated to clamp the casing pipe to start eccentric rotation and press down through the lifting cylinder of the pile pulling device, the casing pipe swings back and forth along with the pile pulling device and surrounds the original old pile to be inserted into the ground until the position is cut off while being at the eccentric position with the original old pile; when the sleeve reaches the target depth of the cut-off pile, the original pile is horizontally cut off by using the torque force of the rotary sleeve and a cutting tool; when the old pile and the sleeve rotate simultaneously, the inverted triangular hammer is taken out, the original pile is fixedly taken out by using a crawler crane, and meanwhile, the residual soil in the sleeve is cleaned; after the first section is cut off, connecting a second section of sleeve by using an interface bolt, continuously rotating and pressing in, and repeating the operation until all the residual original piles are taken out; and after pile pulling is completed, checking the water level condition of the basement, and monitoring the road surface, the existing subway operation line and the structures.
In a preferred embodiment of the present invention, in step S8, after removing the pile position, C20 plain concrete is selected for backfilling; firstly backfilling 20cm above the joint of the bottommost casing pipe, then pulling out one casing pipe, continuously backfilling to 20cm above the joint of the bottommost casing pipe, then pulling out one casing pipe, circulating in sequence until backfilling to the elevation of the pile top, pulling out the last casing pipe, and transferring to the next pile pulling construction.
Compared with the prior art, the invention has the advantages that:
(1) the invention can reinforce the side wall of the underground structure through the counterfort wall and the retaining wall, on one hand, the effective separation between a working surface and the structure which is not removed is realized, and the influence of water seepage and water gushing on the normal use of the surrounding structure is avoided, on the other hand, the stability of the side wall is improved through the structure optimization;
(2) in the top plate dismantling process, the backfill soil is used for filling the underground structure cavity, so that the soil pressure balance of the two sides of the side wall can be ensured, and the construction safety is greatly improved;
(3) the invention adopts the full-rotation full-casing drilling machine, quickly grinds through the concrete bearing platform through the modes of cutter configuration selection and casing pressing, and then carries out pile pulling construction, thereby accelerating the whole pile pulling speed, avoiding the risk of water gushing from the bottom plate and reducing the time for disturbing the stratum;
(4) after the pile body is completely pulled out, the pile body is filled with C20 plain concrete, so that the soil body is guaranteed to be compact;
in conclusion, the method can reduce the influence of underground structure demolition on the surrounding environment to the maximum extent, and the whole construction process is rapid, safe and efficient.
Drawings
FIG. 1 is a process flow diagram of a protective demolition construction method of a basement pile foundation next to an existing subway line in example 1;
fig. 2 is a schematic view of the construction of the retaining wall and buttress wall of example 1.
Detailed Description
The following examples are given for the detailed implementation and specific operation of the present invention, but the scope of the present invention is not limited to the following examples.
Example 1
The Dongzhou subway 6 number line train construction of four office of medium-speed railway group limited company of China is near subway operation line, and the shield construction space will pass the pile foundation of the Dongzhou platform basement of crossing street of train, in order to provide space for the shield construction, need demolish platform and basement of crossing street, pull out the pile foundation again. The distance between the basement floor and the right line of the No. 1 line is only about 11m, the distance between the pile foundation to be dismantled and the No. 4 line of the subway is only 3m, the pile bottom is close to a pressure-bearing water layer, the basement is dismantled, the pile foundation is pulled out, soil pressure release is inevitably caused, the safety of the close-to-operation subway line is affected, and the pressure-bearing water gushing risk is easy to occur. Aiming at the important and difficult points, the embodiment provides a protective dismantling construction method of the basement pile foundation next to the existing subway line, and by means of measures such as basement side wall reinforcement, structure earth backfilling, pile pulling process optimization, concrete pile hole backfilling and the like, the smooth dismantling of the basement structure and the pile foundation is guaranteed, meanwhile, the risk of confined water inrush is avoided, and the deformation stability of the next subway operation line is guaranteed to the maximum extent.
The protective demolition construction method for the basement pile foundation next to the existing subway line in the embodiment is shown in fig. 1 and comprises the following steps:
1. the surface of the basement is cleared and a construction hoisting hole is formed:
and cleaning the original pavement paving layer of the surface layer of the underground structure by using the excavator to clean the pavement. Geological radar detection is carried out on soil layers around the underground structure to be dismantled, and particularly, loose or hollow soil bodies are filled and reinforced at the periphery of adjacent subway lines, so that the soil layers around the construction are compact, and disturbance is reduced.
After the roof place is cleared up out, open the work hole in roof angle side, cut out 2 construction holes 4m by 6m to the roof with the diamond rope, mainly used material is transported backward and is filled back the soil operation. Before cutting, chiseling hoisting holes on the small plates of the pre-divided blocks, wherein 4 hoisting holes are arranged on each small plate, a steel wire rope is arranged in each hoisting hole in a penetrating mode, and the small plates are suspended above the secondary beams through supporting section steel to prevent the plates in the cutting process from falling. The crane selects an 80-ton truck crane for hoisting.
2. And (3) constructing the retaining wall and the buttress wall:
referring to fig. 2, a retaining wall is constructed at the intersection of the underground structure to be removed and the non-removed side, the height of the retaining wall is from the basement floor surface to the top plate bottom surface, the retaining wall is used for separating the working surface of the underground structure to be removed from the non-removed structure, and effective separation between the working surface and the adjacent structure is realized. A drainage ditch and a water collecting well are arranged on the side, close to the non-demolished structure, of the retaining wall, when water flows out, the water can be pumped and drained in a centralized manner, and the influence of water seepage and water gushing on the normal use of surrounding structures is avoided.
Meanwhile, the counterfort side wall construction counterfort wall of the part to be dismantled aims at improving the deformation resistance of the underground structure of the part adjacent to the existing subway line and reducing the influence of the dismantling construction on the existing subway line. The concrete construction process of the buttress wall is as follows:
(1) and (3) bar planting: the juncture of the buttress wall, the retaining wall, the top plate, the side wall and the bottom plate needs to be chiseled, coarse aggregate is chiseled out, the coarse aggregate is blasted completely, the joint part is planted with the steel bar, and the joint part is provided with the water-swelling water stop strip. The steel bar planting glue at the joint of the buttress wall, the top plate and the side wall is strictly controlled according to the gel time and the curing time of a product, a specially-assigned person is required to take care of the constructed steel bars on site before gel, collision is strictly prevented, and a drawing test can be carried out after the glue is completely cured. And (4) unloading after the test value meets the design requirement by adopting nondestructive inspection.
(2) Binding steel bars: and (3) processing and binding steel bars according to the requirements of a drawing, wherein the steel bars must be firmly bound in a crossed manner, and the phenomena of deformation and loosening are avoided. And after the binding of the reinforcing steel bars is finished and the acceptance is qualified, the template can be closed.
(3) Placing a template: and (3) cleaning the bottom die by using an air compressor before sealing the die, installing the template after finishing binding and inspecting the steel bars, and reinforcing by adopting split bolts.
(4) Pouring concrete: c30 concrete is poured in 3 layers, the pouring needs to be continuous, the concrete is reinforced to vibrate, and the concrete is required to be quickly inserted, slowly pulled and vibrated to be compact.
(5) Removing the mold and maintaining: when the concrete reaches the specified strength, the template can be dismantled, and the concrete is covered, moisturized and cured.
3. Backfilling the basement:
and (3) hanging the excavator from the reserved hole of the top plate, backfilling the excavator to the bottom elevation of the top plate of the basement in a layered manner, controlling the backfilling height and the backfilling quality, and plugging the part, which is possibly provided with water leakage, at the periphery of the ground structure. And backfilling by adopting an excavator and a bulldozer, paving backfilled soil layer by layer, wherein the thickness of the paved soil layer is determined according to the soil quality, the compactness requirement and the performance of the machine.
Meanwhile, after the pile foundation of the underground structure is pulled out, the basement upwells, and underground water flows into the underground structure, so that the peripheral water level of the underground structure is unbalanced and flows, the water is poured back into the underground chamber in advance, and the balance of the internal water level and the external water level of the underground structure is ensured.
4. Dismantling a top plate:
firstly, an excavator is adopted to clean an original pavement layer of a basement surface layer, and then sundries on the upper part of a top plate are cleaned, so that a cutting place is provided. The top plate cutting size is determined before cutting, a rope saw is adopted to cut along the side line of the joint of the beam and the plate, and the cut plate is cut into 2 small blocks. And determining the lifting appliance and the safe operation radius according to the lifting load, and ensuring the lifting safety. Use diamond rope cutting basement roof to trompil, the construction flow is as follows:
(1) taking holes and determining a cutting section: before cutting, lifting holes are chiseled on the small plates of the pre-sorting block, 4 lifting holes are arranged on each small plate, and a steel wire rope or an iron chain is arranged in each lifting hole in a penetrating mode to enable the small plates to be suspended above the secondary beam through the supporting section steel so as to prevent the plates in the cutting process from falling.
(2) Fixing the rope saw and the guide wheel: fixing a main foot rest and an auxiliary foot rest of the rope saw by using an M16 anchor bolt; the guide wheel must be mounted stably and the edge of the wheel must be aligned with the centerline of the reeving hole to ensure an effective cutting speed of the cutting surface.
(3) Installing a rope: according to the determined cutting form, the diamond rope is wound on the driving wheel and the auxiliary wheel according to a certain sequence, and the direction of the rope is required to be consistent with the driving direction of the driving wheel.
(4) Cutting construction: starting the electric motor, adjusting the lifting tension of the driving wheel through a control panel to ensure that the diamond rope is properly tightened, supplying circulating cooling water, and then starting the other electric motor to drive the driving wheel to drive the diamond rope to rotate and cut. The stability of the machine base must be closely observed in the cutting process, and the deviation of the guide wheel is adjusted at any time to ensure that the cutting ropes are in the same plane. During the cutting process, cutting parameters are adjusted by operating the control panel to ensure that the running linear speed of the diamond rope is about 20 m/s; on the other hand, enough flushing liquid amount should be ensured in the cutting process to ensure the cooling of the diamond rope and take away the ground powder scraps. The cutting operation has stable speed, stable parameters and stable equipment. It is worth noting that if the top plate is the prestressed plate, cutting stress release should be carried out on the prestressed tendons firstly, a 10-meter warning area is set during cutting, constructors are forbidden to enter a cutting site, and the constructors can enter the site after confirming safety after finishing cutting.
5. Field hardening:
and backfilling the field after the top plate is cut, backfilling earthwork to the level of the field, and compacting by adopting a road roller. And after the backfilling is finished, hardening the area above the basement. C30 concrete is adopted for hardening, heavy construction machinery is considered to be a crawler crane and a full-casing full-slewing drilling machine in the field, and the bearing capacity of the foundation is determined to reach 450kPa through tests.
6. The bottom plate and the bearing platform are broken:
before construction, measurement lofting is carried out on the pile foundation to be pulled, and measurement intersection is carried out on the measurement points after rechecking. And placing a reaction plate according to the measurement point position to ensure that the roadbed is stressed uniformly, hoisting the full-rotation full-casing drilling machine to the reaction plate, checking the central point position of the pile after the drilling machine is in place, and checking whether the pile is empty or not. Then, preparing a first section of sleeve and welding a titanium alloy cutter head; because reinforced concrete structures such as basement bottom plate and cushion cap need be amputated to this embodiment, arrange the scheme for "outer sword + interior sword" convolution cutter, outer sword is at the installation of sleeve pipe end opening sword groove, and interior sword is for evenly welding four tool bits to the sleeve inner wall apart from the mouth of pipe 30cm, can show the speed that promotes concrete structure ground, stir garrulous, improves the efficiency of construction. And finally, connecting the drilling machine with the power box and the operation chamber, hoisting the first section of casing after the drilling machine is initially leveled, and adjusting the horizontal posture of the drilling machine and the vertical posture of the casing to ensure the verticality of the casing. In the construction process, the whole process monitoring measurement is carried out on surrounding buildings and existing subway operation lines, and the influence of the dismantling construction on the surrounding environment is ensured by dynamic control. Once the deformation of the building exceeds the control value, the construction report is immediately stopped, the reason of the overlarge deformation in the construction process is found out, corresponding control measures are taken, and expert review is carried out if necessary.
In order to reduce the influence of the structural bottom plate and the bearing platform to be removed on the subway operation line as much as possible and prevent the underground water from surging during removal, the scheme that the bottom plate and the bearing platform are removed by a full-rotation full-casing drilling machine is adopted, and the following optimization is made:
(1) optimizing a cutter: the combined cutter arrangement of the outer cutter and the inner cutter is adopted to improve the efficiency of cutting the reinforced concrete by the sleeve.
(2) The sleeve pressing mode is optimized: because the maximum pressing force provided by the driving system is the dead weight of the machine body, the drilling machine upper and lower oil cylinders are flexibly utilized in construction. When the upper oil cylinder presses down the clamped sleeve, a corner is lifted on the lower oil cylinder, the dead weight of the machine body is fully utilized, pressure is concentrated on the cutter head on one side of the sleeve, the contact surface of the cutter head and concrete is reduced, the concrete surface is locally crushed and then is uniformly cut, and the purpose of efficiently breaking is achieved.
(3) Parameter optimization: when the concrete structure is cut, the parameters of rotation torque, rotation speed, press-in force and clamping force are strictly controlled, and a uniform speed pipe descending scheme of sleeve pipe slow rotation and medium pressure is adopted, namely the rotation speed of the sleeve pipe is a slow gear, and the downward pressure is a medium gear.
(4) And (3) steel bar cutting inspection: if the reinforcing steel bar cannot be worn in 1 hour, the cutter head is ground flat or the reinforcing steel bar is curled and wound, the cutter head needs to be replaced in time, the reinforcing steel bar is cut manually when necessary, and the average grinding rate of the reinforced concrete is 30cm/h under the general condition.
7. Pile foundation removal:
after a full-rotation full-casing drilling machine is adopted to remove a basement bottom plate and a bearing platform, pile pulling equipment is operated to clamp a casing pipe to start eccentric rotation and press downwards through a lifting cylinder moving up and down of the pile pulling equipment, the casing pipe is rocked back and forth along with the pile pulling equipment to rotate back and forth, and the casing pipe surrounds an original old pile and is inserted into the ground at an eccentric position of the original old pile until the position is cut off; when the sleeve reaches the target depth of the cut-off pile, the original pile is horizontally cut off by utilizing the torque force of the rotary sleeve and a cutting tool; when the old pile and the sleeve rotate simultaneously, the inverted triangular hammer is taken out, the original pile is fixedly taken out by using a crawler crane, and meanwhile, the residual soil in the sleeve is cleaned; after the first section is cut off, connecting a second section of sleeve by using an interface bolt, continuously rotating and pressing in, and repeating the operation until all the residual original piles are taken out; and after pile pulling is finished, checking the water level condition of the basement, and monitoring the road surface, the existing subway line and the structures.
8. Pile position backfilling:
after the pile position is pulled out, in order to ensure that soil body holes are filled in time, and in order to ensure that the backfilling is compact and stable, C20 plain concrete is selected for backfilling, so that the influence of pile pulling construction on the surrounding environment is reduced to the minimum. During specific operation, firstly backfilling the position 20cm above the joint of the bottommost casing pipe, then removing one casing pipe, continuously backfilling until the position 20cm above the joint of the bottommost casing pipe, then removing one casing pipe, circulating in sequence until the backfilling reaches the elevation of the pile top, removing the last casing pipe, and transferring to the next pile pulling construction.
The technology is applied to the Hangzhou subway No. 6 line second-stage engineering civil construction SG6-15 standard train east station and the Hangzhou airport track express line civil construction SGJC-2 standard segment Hangzhou west station, so that the smooth construction of underground structure demolition and pile foundation removal under the working conditions of a high-pressure water layer close to a subway operation line is ensured, and the deformation of the surrounding environment is stable and risk-free through monitoring and measuring data verification. Compared with the method for demolishing the underground structure after reinforcing the surrounding environment by the MJS, the method can effectively solve the difficult problem of safely demolishing the near-pressure-bearing water layer of the underground structure without influencing the surrounding environment.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (10)
1. A protective dismantling construction method for a basement pile foundation next to an existing subway line is characterized by comprising the following steps:
s1: clearing the surface of the basement and forming construction hoisting holes;
s2: constructing a retaining wall at the intersection position of the underground structure to be removed and the side wall not to be removed, and constructing a buttress wall on the side wall of the basement to be removed;
s3: filling the underground structure chamber with backfill soil, and recharging water to ensure the balance of underground water levels inside and outside the basement;
s4: removing the top plate of the basement by cutting with a rope saw;
s5: hardening the area above the basement;
s6: a full-rotation full-casing drilling machine is adopted to remove a basement bottom plate and a bearing platform;
s7: removing the pile foundation;
s8: and after the pile position is pulled out, plain concrete backfilling is carried out.
2. The method for the protective demolition construction of the basement pile foundation next to the existing subway line as claimed in claim 1, wherein in step S1, the original pavement layer of the surface layer of the underground structure is cleaned by a digging machine to clean the pavement; after the roof site is cleared, working holes are formed in the corner sides of the roof for material transfer and backfilling operation.
3. The method of claim 1, wherein in step S2, the height of the retaining wall is from the basement floor surface to the top floor surface for separating the working surface of the underground structure to be removed from the non-removed structure.
4. The protective demolition construction method for basement pile foundation next to existing subway line according to claim 1, wherein in the step S2, the concrete construction flow of the buttress wall is as follows:
(1) and (3) bar planting: chiseling the junctions of the buttress walls, the top plate, the side walls and the bottom plate, chiseling coarse aggregates, and purging; drilling and cleaning holes at positions needing bar planting by using a percussion drill, injecting glue into the holes after emptying, and immediately planting bars after injecting glue;
(2) binding steel bars: the reinforcing steel bars of the buttress wall enter the field and are bound;
(3) placing a template: after the steel bars are bound, installing a template, and reinforcing by adopting split bolts;
(4) pouring concrete: pouring concrete on the baffle;
(5) removing the mold and maintaining: and after the concrete reaches the specified strength, removing the formwork and maintaining.
5. The method for protective demolition construction of basement pile foundation next to existing subway line as claimed in claim 1, wherein in step S3, the excavator is hoisted down from the reserved hole of the top plate and backfilled layer by layer to the bottom elevation of the top plate of the basement; meanwhile, the water is reinjected into the underground chamber, so that the balance of the water level inside and outside the underground structure is ensured.
6. The protective demolition construction method of a basement pile foundation next to an existing subway line according to claim 1, wherein in step S4, an excavator is used to clean an original pavement layer of a basement surface layer, and then sundries on the upper portion of a top plate are cleaned to provide a cutting site; determining the cutting size of the top plate before cutting, cutting along the side line of the joint of the beam and the plate by using a wire saw, and cutting the cut plate into 2 small blocks; and then, determining a lifting appliance and a safe operation radius according to the lifting load to ensure the lifting safety, and cutting the top plate of the basement by using a diamond rope to open a hole.
7. The method for the protective demolition construction of the basement pile foundation next to the existing subway line as claimed in claim 1, wherein in step S5, the site is backfilled after the top slab is cut, and the earthwork is backfilled to the level of the site and compacted by a road roller; after backfilling is finished, hardening the area above the basement, wherein C30 concrete is adopted for hardening, the construction machinery is a crawler crane and a full-casing full-slewing drilling machine, and the bearing capacity of the foundation can reach 450 kPa.
8. The method for the protective demolition construction of the basement pile foundation next to the existing subway line as claimed in claim 1, wherein in step S6, the pile foundation to be pulled is measured and lofted first, and the measurement point is re-checked and then measured to meet the bottom; secondly, placing a reaction plate according to the measuring point position to ensure that the roadbed is stressed uniformly, hoisting a full-rotation full-casing drilling machine to the reaction plate, checking the central point position of the pile after the drilling machine is in place, and checking whether the pile is empty; then preparing a first section of sleeve and welding a titanium alloy cutter head; finally, connecting the drilling machine with the power box and the operation room, hoisting a first section of sleeve after the drilling machine is initially flat, adjusting the horizontal posture of the drilling machine and the vertical posture of the sleeve, and ensuring the verticality of the sleeve; in construction, the whole process monitoring and measuring are carried out on surrounding buildings and existing subway operating lines.
9. The method for the protective demolition construction of the basement pile foundation next to the existing subway line as claimed in claim 1, wherein in step S7, after the basement floor and the bearing platform are broken by the full-circle full-casing drilling machine, the pile pulling equipment is operated to press the casing pipe by the lifting cylinder of the pile pulling equipment moving up and down, the casing pipe swings back and forth with the pile pulling equipment, and surrounds the old pile to insert into the ground until the broken position; when the sleeve reaches the target depth of the cut-off pile, the original pile is horizontally cut off by utilizing the torque force of the rotary sleeve and a cutting tool; when the old pile and the sleeve rotate simultaneously, the inverted triangular hammer is taken out, the original pile is fixedly taken out by using a crawler crane, and meanwhile, the residual soil in the sleeve is cleaned; after the first section is cut off, connecting a second section of sleeve by using an interface bolt, continuously rotating and pressing in, and repeating the operation until all the residual original piles are taken out; and after pile pulling is completed, checking the water level condition of the basement, and monitoring the road surface, the existing subway operation line and the structures.
10. The method for the protective demolition construction of the basement pile foundation next to the existing subway line as claimed in claim 1, wherein in step S8, after the pile position is pulled out, C20 plain concrete is selected for backfilling; firstly backfilling 20cm above the joint of the bottommost casing pipe, then pulling out one casing pipe, continuously backfilling to 20cm above the joint of the bottommost casing pipe, then pulling out one casing pipe, circulating in sequence until backfilling to the elevation of the pile top, pulling out the last casing pipe, and transferring to the next pile pulling construction.
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