CN113482028B - Construction method for breaking open caisson pile - Google Patents
Construction method for breaking open caisson pile Download PDFInfo
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- CN113482028B CN113482028B CN202110533624.XA CN202110533624A CN113482028B CN 113482028 B CN113482028 B CN 113482028B CN 202110533624 A CN202110533624 A CN 202110533624A CN 113482028 B CN113482028 B CN 113482028B
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- 238000010276 construction Methods 0.000 title claims abstract description 45
- 239000004568 cement Substances 0.000 claims abstract description 86
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 64
- 239000010959 steel Substances 0.000 claims abstract description 64
- 238000005520 cutting process Methods 0.000 claims abstract description 61
- 238000005553 drilling Methods 0.000 claims abstract description 54
- 230000002787 reinforcement Effects 0.000 claims abstract description 7
- 239000002689 soil Substances 0.000 claims description 51
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 28
- 238000009412 basement excavation Methods 0.000 claims description 22
- 230000035699 permeability Effects 0.000 claims description 16
- 239000000758 substrate Substances 0.000 claims description 16
- 239000004576 sand Substances 0.000 claims description 15
- 238000005054 agglomeration Methods 0.000 claims description 14
- 230000002776 aggregation Effects 0.000 claims description 14
- 230000002093 peripheral effect Effects 0.000 claims description 11
- 238000000034 method Methods 0.000 claims description 9
- 239000002002 slurry Substances 0.000 claims description 9
- 239000011083 cement mortar Substances 0.000 claims description 7
- 238000011835 investigation Methods 0.000 claims description 7
- 238000004519 manufacturing process Methods 0.000 claims description 7
- 230000035515 penetration Effects 0.000 claims description 6
- FGUUSXIOTUKUDN-IBGZPJMESA-N C1(=CC=CC=C1)N1C2=C(NC([C@H](C1)NC=1OC(=NN=1)C1=CC=CC=C1)=O)C=CC=C2 Chemical compound C1(=CC=CC=C1)N1C2=C(NC([C@H](C1)NC=1OC(=NN=1)C1=CC=CC=C1)=O)C=CC=C2 FGUUSXIOTUKUDN-IBGZPJMESA-N 0.000 claims description 5
- 238000005452 bending Methods 0.000 claims description 5
- 239000003673 groundwater Substances 0.000 claims description 5
- 230000009545 invasion Effects 0.000 claims description 5
- 239000003657 drainage water Substances 0.000 claims description 4
- 238000007689 inspection Methods 0.000 claims description 4
- 238000002955 isolation Methods 0.000 claims description 4
- GNFTZDOKVXKIBK-UHFFFAOYSA-N 3-(2-methoxyethoxy)benzohydrazide Chemical compound COCCOC1=CC=CC(C(=O)NN)=C1 GNFTZDOKVXKIBK-UHFFFAOYSA-N 0.000 claims description 3
- 230000000149 penetrating effect Effects 0.000 claims description 3
- 239000000725 suspension Substances 0.000 claims description 3
- 238000004140 cleaning Methods 0.000 abstract description 2
- 230000003116 impacting effect Effects 0.000 abstract 1
- 230000000903 blocking effect Effects 0.000 description 2
- 238000009435 building construction Methods 0.000 description 2
- 238000003466 welding Methods 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910001294 Reinforcing steel Inorganic materials 0.000 description 1
- 229910000746 Structural steel Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000002893 slag Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D23/00—Caissons; Construction or placing of caissons
- E02D23/08—Lowering or sinking caissons
-
- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D19/00—Keeping dry foundation sites or other areas in the ground
- E02D19/06—Restraining of underground water
- E02D19/12—Restraining of underground water by damming or interrupting the passage of underground water
- E02D19/18—Restraining of underground water by damming or interrupting the passage of underground water by making use of sealing aprons, e.g. diaphragms made from bituminous or clay material
-
- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D23/00—Caissons; Construction or placing of caissons
- E02D23/08—Lowering or sinking caissons
- E02D23/14—Decreasing the skin friction while lowering
-
- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D5/00—Bulkheads, piles, or other structural elements specially adapted to foundation engineering
- E02D5/02—Sheet piles or sheet pile bulkheads
- E02D5/03—Prefabricated parts, e.g. composite sheet piles
- E02D5/04—Prefabricated parts, e.g. composite sheet piles made of steel
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B4/00—Drives for drilling, used in the borehole
- E21B4/06—Down-hole impacting means, e.g. hammers
- E21B4/14—Fluid operated hammers
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- Engineering & Computer Science (AREA)
- Life Sciences & Earth Sciences (AREA)
- Mining & Mineral Resources (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Structural Engineering (AREA)
- Civil Engineering (AREA)
- Paleontology (AREA)
- General Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Geology (AREA)
- Hydrology & Water Resources (AREA)
- Composite Materials (AREA)
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- Earth Drilling (AREA)
Abstract
A construction method for breaking open caisson blocked piles comprises seven steps of making an open caisson sinking scheme, coring by a geological drilling machine to ascertain the depth range of a cement reinforcement body, sinking and excavating the open caisson, erecting an open caisson drilling platform, impacting and breaking a curtain to protrude a pile body by a pneumatic down-the-hole drilling machine, lifting a steel sheet pile cutting curtain to protrude the pile body by a vibrating hammer and sinking the open caisson. The invention is not limited by narrow places, has simple construction operation, large market holding capacity of mechanical equipment, can be quickly put into personnel to mechanically implement cleaning work, has strong operability of the workers, can quickly enter the equipment, ensures the treatment efficiency and the construction period, and has low field entering and exiting cost and good economy.
Description
Technical Field
The invention belongs to the technical field of open caisson construction, and particularly relates to a construction method for breaking open caisson pile.
Background
The open caisson is widely applied to urban construction as an important building structure of municipal engineering and underground structures. The open caisson is a shaft-shaped structure, soil and stones in the well are removed manually or mechanically, and the open caisson gradually sinks to a designed elevation by overcoming the frictional resistance outside a well wall by means of self gravity or other sinking assisting modes; a deep and large open caisson is constructed in a city of a weak water-rich stratum, and a vertical cement reinforcement curtain is generally adopted to isolate the open caisson from water and soil and to reduce the subsidence deformation of the earth surface in the open caisson excavation process.
However, construction of open caisson in city is limited by construction site, design scheme, construction scheme and mechanical choice can not be carried out under ideal conditions, then only backing up is required, then adopting jet grouting pile as vertical curtain scheme, jet grouting pile is a process of cutting and stirring soil body by means of high-pressure water and high-pressure slurry jet, slurry pressure can reach 35-40MPa, when construction site is limited, well wall and construction pile body are small in distance, high-pressure cement slurry diffuses and agglomerates in stratum with good permeability, and pile blocking and sinking occurs when the open caisson sinks.
Disclosure of Invention
The invention aims to provide a construction method for breaking a stuck pile of an open caisson, which aims to solve the technical problem that after cement reinforcement curtains on the periphery of the open caisson invade an excavation surface of the open caisson to solidify and agglomerate, the open caisson sinks to stop sinking.
In order to achieve the above purpose, the invention adopts the following technical scheme:
a construction method for breaking open caisson blocked piles comprises the following construction steps:
step one, a sinking scheme of a sinking well is formulated;
step a, obtaining stratum permeability coefficient, stratum standard penetration number and side friction resistance value according to the geotechnical investigation report;
step b, calculating the sinking safety coefficient of the sinking well through a sinking inspection formula of the sinking well;
step c, adopting two sinking schemes of the open caisson according to the step a and the step b:
first kind: the upper silt layer adopts a drainage submerged scheme, and the second type is that: the lower sand layer adopts a non-drainage underwater sinking scheme;
then determining the number of sections of the well wall of the open caisson, the time and sections for connecting the well wall to the high according to the two excavation schemes, the sinking safety coefficient of the open caisson and the design positions of the plane and the depth of the water-stop curtain of the rotary jet grouting pile of the periphery of the open caisson;
step two, coring by a geological drilling machine to find the invasion range of the protrusion of the cement block;
step d, constructing a jet grouting pile waterproof curtain;
step e, after the jet grouting pile waterproof curtain is finished and before the open caisson is excavated, coring by adopting a geological drilling machine to find out the region position of the cement block protrusion in the depth range of the open caisson, wherein the coring position is positioned outside the edge foot of the open caisson, the coring position is arranged along the circumference of the open caisson, the coring depth reaches the substrate elevation of the open caisson, and a long coring drill rod is adopted for hole guiding and coring to obtain an actual stratum core sample;
step three, sinking excavation of the open caisson, and adopting two open caisson sinking schemes in the step one according to the stratum condition of the open caisson;
step f: when the drainage in the silt stratum sinks, the soil body is symmetrically and uniformly dug from the middle part of the open caisson to the periphery by adopting a digging machine, and the open caisson cutting edge is used for cutting the soil by virtue of dead weight so as to enable the open caisson to sink;
step g: when the sinking well sinks to the depth of the cement block protruding body, observing the sinking rate of the sinking well; when the sinking rate of the open caisson is reduced to the sinking rate of the open caisson, the open caisson clamping pile cannot sink;
step h: digging a cutting edge soil body by adopting a sunk well circumference, digging out a soil body in a gap between a well wall and a rotary jet grouting pile waterproof curtain, and observing the sinking amount of the sunk well;
step i: the diver goes down the well to explore the open caisson cutting edge, confirm the open caisson and suspend the height, through the relative position relation around the open caisson cutting edge, then draw the open caisson cutting edge relative height map; a gap with an annular cross section is formed between the open caisson and the rotary jet grouting pile waterproof curtain and above the position of the cement block protruding body; a breaking device is designed and inserted in the gap, and the breaking device comprises starting equipment positioned above the ground elevation and a breaking vertical piece vertically inserted in the gap and penetrating through the protrusion of the cement block;
step four, erecting an open caisson drilling operation platform;
a drilling platform is erected on the top of the open caisson, the drilling platform is erected on the ground and is positioned right above the open caisson, the drilling platform comprises a group of steel joists which are erected in parallel at intervals, steel plates are fully paved, and then a breaking device, namely a down-the-hole drill, is hung on the drilling platform;
fifthly, the pneumatic down-the-hole drill impacts the cement block protrusion of the broken curtain;
the breaking vertical pieces are vertical first breaking vertical pieces carried by each down-the-hole drill, the first breaking vertical pieces are rod bodies with spherical toothed drill bits, the first breaking vertical pieces are distributed along the peripheral circle of the open caisson cutting edge, the first breaking vertical pieces are densely drilled on the cement block protruding body along the peripheral circle of the open caisson cutting edge according to the diameter of the spherical toothed drill bits, and then the down-the-hole drill is adopted to drive the spherical toothed drill bits to impact and penetrate through the cement block protruding body along the peripheral circle of the open caisson cutting edge until reaching the elevation of a substrate;
step six, a vibrating hammer lifts cement block protruding bodies of the steel sheet pile cutting curtain;
the breaking device further comprises steel sheet pile equipment positioned on the ground outside the open caisson, the steel sheet pile equipment comprises lifting equipment and vertical second breaking vertical pieces controlled by the lifting equipment, the second breaking vertical pieces are steel sheet piles, the steel sheet piles are lifted by the steel sheet pile equipment to sink, the cement block protruding bodies which lose integrity are broken through vibration, the steel sheet piles are symmetrically cut along the open caisson in a circle in a staggered manner during cutting, the cement blocks falling into water are cut off, and the sinking is repeatedly lifted until the pile bottoms of the steel sheet piles reach the substrate elevation;
step seven, sinking the open caisson; when the weight of the open caisson is larger than the friction resistance of the cement block protrusion, the open caisson is subjected to instantaneous sinking, the suspended height of the open caisson from the elevation of the substrate is controlled to be not larger than 1m, and then the open caisson is symmetrically and uniformly excavated to the elevation of the substrate, so that the open caisson is prevented from tilting until the open caisson is completely submerged.
The jet grouting pile waterproof curtain in the step d is applied in the soil body in the stratum range of the open caisson, the soil body in the open caisson is excavated, the groundwater level is lower than the water level in the open caisson,
in the step e, the cement block protruding body is a block body protruding inwards in a circle in the middle of the inner wall of the jet grouting pile waterproof curtain, and the inner diameter of the cement block protruding body is larger than the outer diameter of the open caisson.
In the fourth step, the bending deformation resistance of the profile steel joist at least meets the construction stress requirements of two down-the-hole drilling machines, and the down-the-hole drilling machines are symmetrically distributed on a drilling platform.
In the third step, a method of sectional manufacturing and sectional sinking is adopted, the height of the well wall is considered in advance before the sinking of the open caisson to the protruding body of the cement block, and the construction of the residual well wall of the open caisson is completed before the sinking of the open caisson to the protruding body of the cement block.
In the step e, the number of the coring holes is eight, four holes are vertically crossed, and four holes are obliquely crossed; and the coring point is controlled to be 100mm outside the edge foot of the open caisson for drilling and coring.
In the step f, firstly excavating the soil body in the middle of the open caisson, then symmetrically excavating the soil bodies under the edge foot and outside the edge foot, excavating the soil body in the gap between the edge foot and the isolation pile, and sinking the open caisson by means of dead weight.
In the fifth step, two crawler-type pneumatic down-the-hole drills are adopted, a 2m drill rod is used for drilling, and a spherical tooth drill bit with the diameter of 100mm is arranged.
In the sixth step, when the depth of the open caisson is increased, and the total length of the steel sheet pile is smaller than that of the open caisson, a long rod is welded at the top of the steel sheet pile, and the steel sheet pile is lengthened.
Compared with the prior art, the invention has the following characteristics and beneficial effects:
the invention can rapidly treat the agglomeration of the intrusion-limiting cement to enable the open caisson to sink. The invention is especially suitable for setting the cement reinforcement curtain on the periphery of the well wall of the open caisson, and the cement reinforcement body invades the sinking range of the open caisson to cause the problems of pile blocking, suspension and sinking stopping of the open caisson, and can quickly remove the cement mortar agglomeration invaded in the sinking range of the open caisson to enable the open caisson to sink.
The invention adopts the methods of drilling mechanical crushing and sheet pile cutting to remove the hard cement caking protrusion on the periphery of the well wall of the open caisson. The method of mechanical crushing and sheet pile cutting refers to sinking excavation of the open caisson to empty a vertical soil body in a gap between a well wall and a cement reinforcement curtain, and a cutting edge foot and a substrate are suspended and still cannot sink.
The invention provides a structure for crushing cement blocks, cutting sheet piles and cutting mud blocks falling into water through the impact of a pneumatic down-the-hole drill, which is not limited by a narrow place, is simple in construction operation, large in market holding quantity of mechanical equipment, can be quickly put into personnel for mechanical implementation of cleaning work, is strong in operability of the workers, can be quickly put into the equipment, ensures the treatment efficiency and the construction period, and is low in field entering and exiting cost and good in economy.
Drawings
The invention is described in further detail below with reference to the accompanying drawings.
FIG. 1 is a schematic illustration of the invasion of a perimeter cement-reinforced curtain of an open caisson.
FIG. 2 is a schematic illustration of open caisson perimeter drill coring.
FIG. 3 is a schematic view of a caisson card pile.
Fig. 4 is a schematic cross-sectional view of fig. 3.
Fig. 5 is a schematic view of open caisson pile clamping platform erection and borehole breaking.
Fig. 6 is a schematic top view of fig. 5.
Fig. 7 is a schematic view of cutting of a steel plate of a pile-holding plate of a sunk well.
Reference numerals: 1-jet grouting pile waterproof curtain, 2-open caisson stratum, 201-ground elevation, 202-substrate elevation, 203-groundwater level, 204-water level in the open caisson, 3-open caisson, 301-well wall height, 4-cement block protrusion, 5-geological drilling rig, 6-open caisson excavation face, 601-gap, 7-drilling platform, 701-section steel joist, 702-steel plate, 8-down-the-hole drilling rig, 801-spherical tooth drill bit, 9-steel sheet pile equipment and 901-steel sheet pile.
Detailed Description
1-7, a construction method for breaking open caisson pile, which comprises the following construction steps:
step one, referring to FIG. 1, a sinking scheme of a sunk well 3 is formulated; and (5) predicting the plane, the vertical range and the depth of the cement block protrusion according to geotechnical engineering characteristics and stratum permeability coefficients in a geotechnical investigation report.
Step a, according to the geotechnical investigation report of each soil layer friction and each section depth of the open caisson, understanding geotechnical engineering characteristics, stratum permeability coefficients, checking stratum standard penetration number and side friction resistance values; calculating to obtain the sinking coefficient of the sinking well, and making a sinking scheme of sinking well drainage water and non-drainage water.
And b, calculating the sinking safety system of the well section by using a sinking inspection formula of 6.14.3 of the building construction manual. And judging the plane and depth range of the cement reinforced curtain invading the open caisson according to the vertical and horizontal permeability coefficients of the stratum reported by the geotechnical investigation.
And c, making the height of the front well wall joint of the sinking well, which is sunk to the cement agglomeration area, in advance. Two open caisson sinking schemes are adopted according to the step a and the step b: combining the geotechnical engineering characteristics of the open caisson, the stratum permeability coefficient and the sinking safety coefficient of the open caisson, the comprehensive factors adopt two different sinking schemes, namely the first type: the upper silt layer adopts a drainage submerged scheme, and the second type is that: the lower sand layer adopts a non-drainage underwater sinking scheme; and then determining the number of sections of the well wall of the open caisson, the time and sections for connecting the well wall 301 to the high according to the two excavation schemes, the sinking safety coefficient of the open caisson and the design positions of the plane and the depth of the jet grouting pile waterproof curtain 1 of the circumference of the open caisson.
Mastering and understanding stratum engineering characteristics and mechanical property indexes in a survey report before specific construction, looking up a table to obtain standard penetration numbers and side friction resistance values of each soil layer, controlling the height of a first section of well wall of an open caisson to be 3-5m, taking the height of a multilayer plate on site as a modulus, constructing a 3.6m high well wall structure, and preventing a 250mm cutting edge from being deformed and cracked due to the fact that the contact surface between the cutting edge and a foundation is smaller after well wall pouring is completed; according to the structure height of 18.4m of the open caisson, adopting a method of manufacturing the open caisson in sections and sinking the open caisson in sections, manufacturing the open caisson in five sections, sinking the open caisson for three times, and dividing the construction section of the structure with the height of 3.6m of each section; after the sinking well height is preliminarily determined, the sinking resistance standard value of the weighted average of the comprehensive multi-layer soil in the well wall height range of each section is calculated by utilizing the sinking inspection calculation of the building construction calculation manual 6.14.3, then the sinking well can be smoothly sunk when the sinking coefficient of each section is larger than the sinking safety coefficient of 1.2 according to the dead weight of the sinking well and the surrounding constraint conditions, after the sinking coefficient is calculated, the scheme of adopting the drainage underwater sinking and the non-drainage underwater sinking is determined according to the stratum soil permeability coefficient of the sinking position of each section of the well wall, the water-drainage underwater sinking excavation is adopted for the silt soil which is not permeable above 11.07m in the sinking well depth, the sinking speed is accelerated, the water-drainage underwater sinking is adopted for the sand layer which is strongly permeable below 11.07m, the water level in the sinking well reaches 1m above the ground water level, and the water-stop curtain seam sand leakage of the sinking well is prevented, and the ground subsidence is caused.
Specifically, according to the permeability coefficient of each stratum at the sinking depth position of the open caisson, judging the range of invasion of curtain cement slurry into the open caisson, wherein the horizontal and vertical permeability coefficients of a sand layer in the stratum at the sinking depth of the open caisson are 25m/d, and the pile-forming jet flow pressure is usually 30-40 Mpa by adopting a high-pressure jet grouting pile as a waterproof curtain, so that the injected cement slurry is further expanded and permeated outside the reinforced stratum under the pushing of water pressure and slurry pressure.
The height of the open caisson is considered in advance before the open caisson sinks to a cement agglomeration area, the construction of the remaining 2 sections of well walls of the open caisson is completed before the open caisson reaches the cement agglomeration area, the open caisson can be increased in dead weight firstly, the open caisson is prevented from sinking rapidly after cement mortar agglomeration is eliminated secondly, soil above the well walls is free of supporting, and the safety risk of collapse of the well walls of the open caisson is achieved.
Step two, referring to fig. 2, the geological drilling rig 5 performs coring to find the invasion range of the cement block protrusion; and after the construction of the jet grouting pile waterproof curtain is completed, drilling and coring along the peripheral ring of the outer wall of the open caisson to ascertain the plane, the vertical range and the depth of the protruding body of the cement block.
And d, constructing a jet grouting pile waterproof curtain. The rotary jet grouting pile waterproof curtain 1 is applied in soil body in the range of the open caisson stratum 2, the soil body in the open caisson 3 is excavated, the top standard height of the open caisson does not exceed the water level 204 in the open caisson, and the underground water level 203 is lower than the water level 204 in the open caisson.
And e, after the jet grouting pile waterproof curtain is to be completed and before the open caisson is excavated, coring by adopting a geological drilling machine 5 to find the region position of a cement block protrusion in the depth range of the open caisson, wherein the cement block protrusion 4 is a block body protruding inwards in a circumferential direction in the middle of the inner wall of the jet grouting pile waterproof curtain 1, and the inner diameter of the cement block protrusion 4 is larger than the outer diameter of the open caisson 3.
The coring position is positioned outside the edge foot of the open caisson, is arranged along the circumference of the open caisson, and the coring depth reaches the base elevation 202 of the open caisson, and the core is obtained by adopting a long coring drill rod to drill holes, so that the actual stratum core sample is obtained to the maximum extent.
Specifically, an XY-180 geological drilling machine is adopted for drilling and coring; coring depth is from the ground to the elevation of the bottom of the open caisson; the number of the coring holes is eight, four holes are vertically crossed, and four holes are obliquely crossed; the coring point is controlled to be 100mm outside the edge foot of the open caisson for drilling and coring; the coring drill rod is 3.3m long and is used for coring, a core sample is collected to the greatest extent, and the strength of the cement paste intrusion section and the cement paste block in the depth range of the open caisson is ascertained.
3, referring to figures 3-4, sinking and excavating the open caisson, and adopting two open caisson sinking schemes in the step one according to the stratum condition of the open caisson; the sinking well is sunk to the depth of the protruding body of the cement block, and the sinking rate of the sinking well is observed. The open caisson excavation face 6 is shown. The method of sectional manufacturing and sectional sinking is adopted, the height of the well wall is considered in advance before the sinking of the open caisson to the cement block protruding body 4, and the construction of the residual well wall of the open caisson is completed before the sinking of the open caisson to the cement block protruding body 4 is completed.
Step f: when the drainage in the silt stratum sinks, in the silt stratum, the sinking coefficient of the sinking well is large, in order to prevent the sinking well from sinking too fast, soil is dug symmetrically and uniformly from the middle part of the sinking well to the periphery by adopting a digging machine, and the sinking well is enabled to sink by cutting soil by cutting edge feet of the sinking well by means of dead weight.
Step g: when the sinking well sinks to the depth range of the cement block protruding body, observing the sinking rate of the sinking well; when the sinking rate of the open caisson is obviously reduced and the open caisson hovers, the open caisson pile cannot sink.
Step h: digging a cutting edge soil body by adopting a peripheral ring of the open caisson, digging out a soil body in a gap between a well wall and a rotary jet grouting pile waterproof curtain, and observing the sinking amount of the open caisson.
Step i: the diver goes down the well to explore the open caisson cutting edge, confirm the open caisson and suspend the height, through the relative position relation around the open caisson cutting edge, then draw the open caisson cutting edge relative height map; a gap 601 with an annular cross section is formed between the open caisson 3 and the jet grouting pile waterproof curtain 1 and above the position of the cement block protruding body 4; a breaking device is designed and inserted into the gap 601, and the breaking device comprises starting equipment above the ground elevation 201 and a breaking vertical piece vertically inserted into the gap 601 and penetrating through the cement block protrusion 4.
The front three sections of the open caisson are 10.8m in the silt layer, an underwater sinking excavation scheme is adopted, the middle excavation of the open caisson extends to the peripheral cutting edge feet, the depth of each excavation is 0.5m, and if the excavation is not sinking, the excavation depth is 0.5m, so that the open caisson is stably and evenly cut into soil and sink; when the sinking well is sunk to below 11.08m and enters a fine sand layer containing mud, groundwater is a pressure-bearing water layer, a non-drainage underwater sinking scheme is adopted, friction resistance in the sand layer is increased, when the sinking well is sunk slowly, four and five sections of well walls of the sinking well are firstly manufactured on the ground, the non-drainage underwater sinking is carried out, a scheme of digging a cutting edge foot is adopted, soil in the middle of the sinking well is firstly dug, soil under the cutting edge foot and outside the cutting edge foot is symmetrically dug, soil in a 700mm gap between the cutting edge foot and an isolation pile is dug out, and the sinking well is sunk by means of dead weight.
When the sinking well sinks to the range of the cement agglomeration section, the elevation of the sinking well is observed, the sinking rate is 1-2cm per hour, or the sinking well is suspended and stopped sinking, the periphery of the well wall of the sinking well is considered to be closely attached to the protruding cement agglomeration body, and the sinking well is blocked with piles and cannot sink. At this time, the diver goes down the well to explore the open caisson cutting edge, confirm the open caisson height, the relative position relation around the open caisson cutting edge, and then draw the open caisson cutting edge relative height map.
Step four, referring to fig. 5-6, setting up an open caisson drilling operation platform.
A drilling platform 7 is erected on the top of the open caisson, the drilling platform 7 is erected on the ground and is positioned right above the open caisson, the drilling platform comprises a group of profile steel joists 701 which are erected in parallel at intervals, a steel plate 702 is fully paved, and then a breaking device, namely a down-the-hole drill 8, is hung on the drilling platform 7; the section steel joist 701 is made of I-steel, and the I-steel joist is placed by utilizing the concave nodes of the prefabricated beam of the cover plate on the top surface of the open caisson, and then a steel plate is fully paved. The bending deformation resistance of the profile steel joist 701 at least meets the construction stress requirements of two down-the-hole drilling machines 8, and the down-the-hole drilling machines 8 are symmetrically distributed on the drilling platform 7.
Specifically, three I-beams of work 40a are arranged in a roof beam groove reserved in a circular open caisson roof structure with the diameter of 9.2m to serve as supporting beams, a 10mm steel plate is fully paved on the upper part, two drilling machines in the most unfavorable state are simultaneously constructed in one I-beam span according to the weight of 100KN of the two down-the-hole drilling machines, and the maximum normal stress of the lower side of the span is calculated to be 174.66KN/mm 2 The bending strength of the carbon structural steel Q235 is 215KN/mm according to the design strength index of 4.4 sections of steel materials of steel structural Standard 2 The bending strength is 0.852 < 1, and meets the acceptance requirement.
Step five, referring to fig. 5-6, the pneumatic down-the-hole drill impacts the cement block protrusions of the broken curtain.
Each down-the-hole drill 8 is provided with a vertical first breaking vertical part, the first breaking vertical part is a rod body with a spherical tooth drill bit 801, the first breaking vertical parts are distributed along the peripheral circle of the open caisson cutting edge, the first breaking vertical parts are densely drilled on the cement block protrusion 4 along the peripheral circle of the open caisson cutting edge according to the diameter of the spherical tooth drill bit 801, then the down-the-hole drill 8 is used for driving the spherical tooth drill bit 801 to impact and penetrate through the cement block protrusion 4 along the peripheral circle of the open caisson cutting edge until reaching the substrate elevation 202, and the impact breaking reveals the cement block protrusion 4 in the sand layer area of 3.6 m.
Specifically, two crawler-type pneumatic down-the-hole drills are adopted, a 2m drill rod is used for drilling, a spherical tooth drill bit with the diameter of 100mm is configured, and the drill bits are densely arranged for drilling; the impact energy of the drilling machine is 11kg/m, the impact frequency is 80 times/min, and the disclosed cement caking area with the sand layer depth of 3.6m is crushed; the perimeter of the open caisson is 32m, the number of holes is 267, 40 down-the-hole drills can be constructed in one day, and a plurality of down-the-hole drills can be arranged according to the needs.
Step six, referring to fig. 7, the vibration hammer pulls out the concrete block protrusion of the steel sheet pile cutting curtain.
The breaking device further comprises steel sheet pile equipment 9 positioned on the ground outside the open caisson, the steel sheet pile equipment 9 comprises lifting equipment and vertical second breaking vertical pieces controlled by the lifting equipment, the second breaking vertical pieces are steel sheet piles 901, the steel sheet piles are lifted by the steel sheet pile equipment 9 to sink, the cement block protruding bodies 4 losing integrity are vibrated and broken, the steel sheet piles are symmetrically cut along the periphery of the open caisson in a staggered mode during cutting, mud falling blocks are cut, and the pile bottoms of the steel sheet piles are repeatedly lifted and sunk until the substrate elevation 202 is achieved.
Specifically, a DX500 type steel sheet pile machine and a 15m Lasen IV type steel sheet pile are adopted, cement mortar blocks which have lost integrity are drilled and crushed on the periphery of the open caisson, the cement blocks are removed and slumped to the bottom of the well through vibration sinking cutting of the steel sheet pile, and the open caisson is sunk by means of dead weight.
When the depth of the open caisson is increased, and the total length of the steel sheet pile is smaller than that of the open caisson, a lengthening rod is welded at the top of the steel sheet pile 901, and the steel sheet pile is lengthened. Lengthening and welding the two sides of the web plate by adopting a construction process of welding the upper strips and reinforcing steel bars with the diameter of 25; the sequence of the steel sheet pile cutting pile bodies should be symmetrical and staggered to lift the steel sheet piles, so that the open caisson can sink uniformly and stably by means of dead weight, and inclination is prevented.
Step seven, sinking the open caisson; when the weight of the open caisson is larger than the friction resistance of the cement block protruding body, the open caisson is subjected to instantaneous sinking, so that the sinking shaft bottom excavation depth is controlled before drilling, the suspension height of the open caisson from the substrate elevation 202 is controlled to be not larger than 1m, a long-arm excavator is adopted to excavate, crush and cut the slag soil and cement mortar block at the shaft bottom after the open caisson is submerged, the open caisson is symmetrically and uniformly excavated to the substrate elevation, and the open caisson is prevented from inclining until the open caisson is submerged.
Claims (5)
1. The construction method for breaking the open caisson pile is characterized by comprising the following construction steps:
firstly, formulating a sinking scheme of an open caisson (3), and pre-judging the plane, vertical range and depth of a cement block protrusion according to geotechnical engineering characteristics and stratum permeability coefficients in a geotechnical investigation report;
step a, according to the geotechnical investigation report of each soil layer friction and each section depth of the open caisson, understanding geotechnical engineering characteristics, stratum permeability coefficients, checking stratum standard penetration number and side friction resistance values; calculating to obtain a sinking coefficient of the sinking well, and making a sinking scheme of sinking the sinking well in the water of the sinking well row and sinking the sinking well in the water of the sinking well row; step b, calculating the sinking safety coefficient of the sinking well through a sinking inspection formula, and judging the plane and depth range of the cement reinforcement curtain which invades the sinking well according to the vertical and horizontal permeability coefficients of the stratum reported by the rock-soil investigation;
step c, making the height of the front well wall joint of the sinking well to the cement agglomeration area in advance, adopting two sinking schemes of the sinking well according to the step a and the step b, and combining the geotechnical engineering characteristics of the sinking well, the stratum permeability coefficient and the sinking safety coefficient of the sinking well: first kind: the upper silt layer adopts a drainage submerged scheme, and the second type is that: the lower sand layer adopts a non-drainage underwater sinking scheme;
then determining the number of sections of the well wall of the open caisson, the time and sections for connecting the well wall to the high according to the two excavation schemes, the sinking safety coefficient of the open caisson and the design positions of the plane and the depth of the rotary jet grouting pile waterproof curtain (1) of the circumference of the open caisson,
controlling the height of a first section of well wall of the open caisson to be 3-5m, taking the height of a multilayer plate as a modulus, constructing a 3.6m high well wall structure, and preventing the contact surface of a 250mm cutting edge foot and a foundation from being small after well wall pouring is finished, so that the cutting edge foot concentrated stress structure is deformed and cracked; the open caisson structure is 18.4m high, a method of sectional manufacturing and sectional sinking is adopted, five sections are manufactured, sinking is carried out for three times, and each section is divided into structural construction sections with the height of 3.6 m; after preliminary determination of the height of the open caisson, carrying out open caisson subsidence checking calculation, calculating the standard value of the friction force of the weighted average of comprehensive multi-layer soil in the height range of each section of well wall, bringing the standard value into a subsidence system balance formula according to the dead weight of the open caisson and the surrounding constraint conditions, calculating the open caisson to be smoothly sunk when each section of subsidence coefficient is larger than the subsidence safety coefficient of 1.2, and determining a scheme for adopting water drainage and water non-drainage according to the stratum soil permeability coefficient of the subsidence position of each section of well wall;
the silt soil with the depth of more than 11.07m is water-proof and is excavated by adopting drainage water for sinking, so that the sinking speed is accelerated, the sand layer with the depth of less than 11.07m is water-proof and is sunk by adopting non-drainage water, the water level in the sunk well reaches 1m above the underground water level, and the water and sand leakage of the seam of the water-proof curtain of the sunk well is prevented, so that the ground outside the sunk well is collapsed;
judging the range of penetration of curtain cement slurry into the open caisson according to the permeability coefficient of each stratum at the sinking depth position of the open caisson, wherein the horizontal and vertical permeability coefficients of a sand layer in the stratum at the sinking depth of the open caisson are 25m/d, and the pile-forming jet flow pressure is usually 30-40 Mpa by adopting a high-pressure jet grouting pile as a waterproof curtain, so that the injected cement slurry is further subjected to external expansion penetration outside the reinforced stratum under the pushing of water pressure and slurry pressure;
the height of the open caisson is considered in advance before the open caisson sinks to a cement agglomeration area, and the construction of the two remaining sections of well walls of the open caisson is completed before the open caisson reaches the cement agglomeration area, so that the open caisson is increased in dead weight firstly, the open caisson is prevented from sinking rapidly after cement mortar agglomeration is removed secondly, soil above the well walls is free of supporting, and the safety risk of collapse of the open caisson is caused;
step two, coring by a geological drilling machine to find the invasion range of the protrusion of the cement block: drilling holes along the peripheral ring of the outer wall of the open caisson to core and find out the plane, vertical range and depth of the protruding body of the cement block after the construction of the jet grouting pile waterproof curtain is completed;
step d, constructing a jet grouting pile waterproof curtain; the rotary jet grouting pile waterproof curtain (1) is applied in soil in the range of an open caisson stratum (2), soil in the open caisson (3) is excavated, the top standard height of the open caisson does not exceed the water level (204) in the open caisson, and the underground water level (203) is lower than the water level (204) in the open caisson;
step e, after the jet grouting pile waterproof curtain is finished and before the open caisson is excavated, coring by adopting a geological drilling machine (5) to find out the position of the region of the cement block protrusion in the depth range of the open caisson, wherein the coring position is positioned outside the edge foot of the open caisson, and is arranged along the circumference of the open caisson, the coring depth reaches the substrate elevation (202) of the open caisson, and the core sample of the actual stratum is obtained by adopting a long coring drill rod to conduct hole coring;
coring depth is from the ground to the elevation of the bottom of the open caisson; the number of the coring holes is eight, four holes are vertically crossed, and four holes are obliquely crossed; the coring point is controlled to be 100mm outside the edge foot of the open caisson for drilling and coring; coring a core drill rod by adopting a drill rod with the length of 3.3m, collecting a core sample to the greatest extent, and ascertaining the strength of a cement paste intrusion section and a cement mortar block in the depth range of the open caisson;
step three, sinking excavation of the open caisson, and adopting two open caisson sinking schemes in the step one according to the stratum condition of the open caisson; sinking the open caisson to the depth of the cement block protrusion, observing the sinking rate of the open caisson, adopting a method of manufacturing the open caisson in sections and sinking in sections, taking the height of the well wall connected with the height into consideration before the open caisson is sunk to the cement block protrusion (4), and completing the construction of the rest well wall of the open caisson before the open caisson reaches the cement block protrusion (4);
step f: when the drainage in the silt stratum sinks, the soil body is symmetrically and uniformly dug from the middle part of the open caisson to the periphery by adopting a digging machine, and the open caisson cutting edge is used for cutting the soil by virtue of dead weight so as to enable the open caisson to sink;
step g: when the sinking well sinks to the depth of the cement block protruding body, observing the sinking rate of the sinking well; when the sinking rate of the open caisson is reduced to the sinking rate of the open caisson, the open caisson clamping pile cannot sink;
step h: digging a cutting edge soil body by adopting a sunk well circumference, digging out a soil body in a gap between a well wall and a rotary jet grouting pile waterproof curtain, and observing the sinking amount of the sunk well;
step i: the diver goes down the well to explore the open caisson cutting edge, confirm the open caisson and suspend the height, through the relative position relation around the open caisson cutting edge, then draw the open caisson cutting edge relative height map; a gap (601) with an annular cross section is formed between the open caisson (3) and the jet grouting pile waterproof curtain (1) and above the position of the cement block protruding body (4); a breaking device is designed and inserted into the gap (601), and the breaking device comprises starting equipment positioned above the ground elevation (201) and a breaking vertical piece vertically inserted into the gap (601) and penetrating through the cement block protrusion (4);
the front three sections 10.8m of the open caisson are positioned in a silt layer, an underwater sinking excavation scheme is adopted, the middle excavation of the open caisson extends to the peripheral cutting edge, the depth of each excavation is 0.5m, and if the excavation is not sinking, the excavation depth is 0.5m, so that the open caisson is stably and evenly cut into soil and sink; when the sinking well sinks to below 11.08m and enters a fine sand layer containing mud, groundwater is a pressure-bearing water layer, a non-drainage underwater sinking scheme is adopted, friction resistance in the sand layer is increased, when the sinking well is slowed down, four and five sections of well walls of the sinking well are firstly manufactured on the ground, the non-drainage underwater sinking is carried out, a scheme of digging a cutting edge foot is adopted, soil in the middle of the sinking well is firstly dug, soil under the cutting edge foot and outside the cutting edge foot are symmetrically dug out, and soil in a 700mm gap between the cutting edge foot and a isolation pile is dug out, so that the sinking well is sunk by means of dead weight;
when the sunk well is sunk to the range of the cement agglomeration section, observing the elevation of the sunk well, wherein the sinking rate is 1-2cm per hour or the sunk well is suspended to stop sinking, and the periphery of the well wall of the sunk well is closely attached to the protruded cement agglomeration body, the sunk well is blocked with piles and cannot sink, when a diver is sunk, probing the edge of the sunk well, confirming the suspension height of the sunk well, the relative position relationship of the periphery of the edge of the sunk well, and then drawing a relative height map of the edge of the sunk well;
step four, erecting an open caisson drilling operation platform;
a drilling platform (7) is erected on the top of the open caisson, the drilling platform (7) is erected on the ground and is positioned right above the open caisson, the drilling platform comprises a group of profile steel joists (701) which are erected in parallel at intervals, a steel plate (702) is fully paved, and then a breaking device, namely a down-the-hole drill (8), is hung on the drilling platform (7);
fifthly, the pneumatic down-the-hole drill impacts the cement block protrusion of the broken curtain;
each down-the-hole drill (8) is provided with a vertical first breaking vertical part, the first breaking vertical part is a rod body with a spherical tooth drill bit (801), the first breaking vertical parts are distributed along the circumference of the open caisson cutting edge, the first breaking vertical parts are densely drilled on the cement block protruding body (4) along the circumference of the open caisson cutting edge according to the diameter of the spherical tooth drill bit (801), and then the down-the-hole drill (8) is adopted to drive the spherical tooth drill bit (801) to impact and penetrate through the cement block protruding body (4) along the circumference of the open caisson cutting edge until reaching a substrate elevation (202);
step six, a vibrating hammer lifts cement block protruding bodies of the steel sheet pile cutting curtain;
the breaking device further comprises steel sheet pile equipment (9) positioned on the ground outside the open caisson, the steel sheet pile equipment (9) comprises lifting equipment and vertical second breaking vertical pieces controlled by the lifting equipment, the second breaking vertical pieces are steel sheet piles (901), the steel sheet pile equipment (9) lifts the steel sheet piles to sink, the steel sheet piles vibrate and crush cement block protrusions (4) which lose integrity, the steel sheet piles symmetrically cut along the open caisson in a circle, staggered manner and cut out mud agglomerates in the water during cutting, the sinking is repeatedly lifted, and the pile bottoms of the steel sheet piles reach the substrate elevation (202);
the steel sheet pile (901) is a 15m Lassen IV type steel sheet pile, cement mortar blocks which are broken by drilling holes on the periphery of the open caisson and lose integrity are removed and collapsed to the bottom of the well by vibrating sinking cutting of the steel sheet pile, and the open caisson is sunk by self weight;
step seven, sinking the open caisson; when the weight of the open caisson is larger than the friction resistance of the cement block protrusion, the open caisson is instantaneously submerged, the suspended height of the open caisson from the substrate elevation (202) is controlled to be not larger than 1m, then the open caisson is symmetrically and uniformly excavated to the substrate elevation, the open caisson is prevented from tilting until the open caisson is completely submerged,
in the step d, the jet grouting pile waterproof curtain (1) is applied in the soil body in the range of the open caisson stratum (2), the soil body in the open caisson (3) is excavated, the underground water level (203) is lower than the water level (204) in the open caisson,
in the step e, the cement block protruding body (4) is a block body protruding inwards in a circle in the middle of the inner wall of the rotary jet grouting pile waterproof curtain (1), the inner diameter of the cement block protruding body (4) is larger than the outer diameter of the open caisson (3),
in the third step, a method of sectional manufacturing and sectional sinking is adopted, the height of the well wall is considered in advance before the open caisson sinks to the cement block protruding body (4), the construction of the residual well wall of the open caisson is completed before the open caisson reaches the cement block protruding body (4),
in the step f, firstly excavating the soil body in the middle of the open caisson, then symmetrically excavating the soil bodies under the edge foot and outside the edge foot, excavating the soil body in the gap between the edge foot and the isolation pile, and sinking the open caisson by means of dead weight.
2. The construction method for breaking open caisson clamping piles according to claim 1, wherein the construction method comprises the following steps: in the fourth step, the bending deformation resistance of the profile steel joist (701) at least meets the construction stress requirements of two down-the-hole drilling machines (8), and the down-the-hole drilling machines (8) are symmetrically distributed on the drilling platform (7).
3. The construction method for breaking open caisson clamping piles according to claim 1, wherein the construction method comprises the following steps: in the step e, the number of the coring holes is eight, four holes are vertically crossed, and four holes are obliquely crossed; and the coring point is controlled to be 100mm outside the edge foot of the open caisson for drilling and coring.
4. The construction method for breaking open caisson clamping piles according to claim 1, wherein the construction method comprises the following steps: in the fifth step, two crawler-type pneumatic down-the-hole drills are adopted, a 2m drill rod is used for drilling, and a spherical tooth drill bit with the diameter of 100mm is arranged.
5. The construction method for breaking open caisson clamping piles according to claim 1, wherein the construction method comprises the following steps: in the sixth step, when the depth of the open caisson is increased, and the total length of the steel sheet pile is smaller than the depth of the open caisson, a long rod is welded at the top of the steel sheet pile (901), and the steel sheet pile is lengthened.
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