CN117166515A - Karst bridge pile foundation construction method - Google Patents
Karst bridge pile foundation construction method Download PDFInfo
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- CN117166515A CN117166515A CN202311122147.3A CN202311122147A CN117166515A CN 117166515 A CN117166515 A CN 117166515A CN 202311122147 A CN202311122147 A CN 202311122147A CN 117166515 A CN117166515 A CN 117166515A
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- 238000010276 construction Methods 0.000 title claims abstract description 50
- 238000005553 drilling Methods 0.000 claims abstract description 60
- 239000002002 slurry Substances 0.000 claims abstract description 45
- 239000004927 clay Substances 0.000 claims abstract description 35
- 239000004576 sand Substances 0.000 claims abstract description 33
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 32
- 239000010959 steel Substances 0.000 claims abstract description 32
- 239000004575 stone Substances 0.000 claims abstract description 19
- 238000000034 method Methods 0.000 claims abstract description 17
- 239000004568 cement Substances 0.000 claims abstract description 7
- 230000015572 biosynthetic process Effects 0.000 claims abstract description 6
- NLYAJNPCOHFWQQ-UHFFFAOYSA-N kaolin Chemical compound O.O.O=[Al]O[Si](=O)O[Si](=O)O[Al]=O NLYAJNPCOHFWQQ-UHFFFAOYSA-N 0.000 claims abstract description 5
- 239000011435 rock Substances 0.000 claims description 18
- 239000002689 soil Substances 0.000 claims description 17
- 230000005484 gravity Effects 0.000 claims description 10
- 230000001681 protective effect Effects 0.000 claims description 10
- 238000004140 cleaning Methods 0.000 claims description 9
- 238000002360 preparation method Methods 0.000 claims description 9
- 239000011148 porous material Substances 0.000 claims description 8
- 238000004080 punching Methods 0.000 claims description 7
- 239000007788 liquid Substances 0.000 claims description 6
- 230000002829 reductive effect Effects 0.000 claims description 6
- 238000005056 compaction Methods 0.000 claims description 5
- 230000002787 reinforcement Effects 0.000 claims description 5
- 229920006395 saturated elastomer Polymers 0.000 claims description 5
- 230000000903 blocking effect Effects 0.000 claims description 4
- 238000010586 diagram Methods 0.000 claims description 4
- 239000002893 slag Substances 0.000 claims description 4
- 239000000084 colloidal system Substances 0.000 claims description 3
- 239000000463 material Substances 0.000 claims description 3
- 238000009527 percussion Methods 0.000 claims description 3
- 238000001556 precipitation Methods 0.000 claims description 3
- 230000008569 process Effects 0.000 claims description 3
- 238000000926 separation method Methods 0.000 claims description 3
- 238000002791 soaking Methods 0.000 claims description 3
- 230000003116 impacting effect Effects 0.000 claims description 2
- 238000003466 welding Methods 0.000 claims description 2
- 238000011161 development Methods 0.000 description 12
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 5
- 235000019738 Limestone Nutrition 0.000 description 4
- 239000006028 limestone Substances 0.000 description 4
- 230000003449 preventive effect Effects 0.000 description 4
- 235000019994 cava Nutrition 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 230000000877 morphologic effect Effects 0.000 description 3
- 230000009467 reduction Effects 0.000 description 3
- 238000013461 design Methods 0.000 description 2
- 238000009933 burial Methods 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 230000003628 erosive effect Effects 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 230000002706 hydrostatic effect Effects 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- 230000000670 limiting effect Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 239000004570 mortar (masonry) Substances 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 230000003405 preventing effect Effects 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 230000001932 seasonal effect Effects 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 230000001502 supplementing effect Effects 0.000 description 1
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- Placing Or Removing Of Piles Or Sheet Piles, Or Accessories Thereof (AREA)
Abstract
The invention provides a karst bridge pile foundation construction method, which comprises the following steps of: (1) overburden drilling: adopting clay mud to protect the wall and drilling a plain filling layer in a small stroke; when entering and passing through the powdery clay layer, adopting clay slurry to protect the wall and carrying out drilling by a small stroke; when the sand layer with the thickness less than 2m drills, adopting cement slurry to protect the wall and performing drilling with a small stroke; when a silt layer with the thickness less than 2m is drilled, 1:1 piece of stone clay backfill treatment is adopted; (2) formation drilling: and a steel pile casing is adopted for follow-up in a closed karst cave or a communicated karst cave with the height of more than 3 m. The method of the invention is used for karst pile foundation construction in karst basin, which can greatly reduce the probability of occurrence of inclined holes, buried drill, stuck drill, falling drill and collapse of karst pile foundation.
Description
Technical Field
The invention relates to the field of bridge pile foundation construction, in particular to a karst bridge pile foundation construction method.
Background
The domestic high-speed railway traffic network is gradually perfected, the bridge occupies less area, the environmental impact is small, and the high-speed railway traffic network becomes the first choice of high-speed railway. When the railway passes through the karst section, the bridge pile foundation in the karst area becomes a serious difficulty in bridge construction. In a karst basin, drilling geology reveals that the underlying bedrock is the water measuring section (C 1 dc) carbonaceous limestone and pebble limestone, karst mainly takes the forms of solution gaps, medium and small karst caves, beaded karst caves and the like, karst is shallow covered, karst development intensity is classified into medium-strong development, karst development zones are mainly located in season fluctuation zones, vertical and horizontal karst morphological development and local karst caves are deeply buried. When karst pile foundation construction is carried out on the karst basin, safety risks such as inclined holes, buried drill, drill sticking, drill falling and collapse of the karst pile foundation easily occur.
Disclosure of Invention
The invention aims at: aiming at the problems existing in the prior art, the karst bridge pile foundation construction method is provided, and the problems that the karst pile foundation construction is carried out on a karst basin, and safety risks such as inclined holes, buried drills, stuck drills, drill falling and collapse of the karst pile foundation are easy to occur are solved.
The invention aims at realizing the following technical scheme:
the construction method of the karst bridge pile foundation comprises the following steps of drilling the karst pile foundation:
(1) Overburden drilling
Adopting clay mud to protect the wall and drilling a plain filling layer in a small stroke;
when entering and passing through the powdery clay layer, adopting clay slurry to protect the wall and carrying out drilling by a small stroke;
when the sand layer with the thickness less than 2m drills, adopting cement slurry to protect the wall and performing drilling with a small stroke;
when the sand layer with the thickness of more than 2m drills, the steel casing is adopted to drill through the sand layer in a follow-up way;
when a silt layer with the layer thickness less than 2m is drilled, 1:1 piece of stone clay backfill treatment is adopted;
when a silt layer with the thickness of more than 2m drills, a steel casing is adopted to drill through the sand layer;
(2) Rock formation drilling
Backfilling the stone clay to the karst cave top of 1.5m by adopting a 1:1 stone clay filling compaction method in a karst region with the karst cave height of less than 3m, and repeatedly drilling and backfilling until the slurry liquid level is stable and does not drop;
and (3) adopting a steel pile casing to follow up at the closed karst cave or the communicated karst cave with the height of more than 3m, wherein the steel pile casing is followed up to the height of 0.5m at the bottom of the karst cave, and adopting a double-layer steel pile casing to follow up at the pile position with the multilayer karst cave.
As a further technical scheme, the construction method comprises the following preparation work before construction:
(1) Preparation for internal industry
Designing pile length and geological data in the pier pile foundation geological display diagram to determine the pile foundation construction sequence;
(2) Preparation for field use
Each pier of the karst bridge is provided with 1 percussion drill, and before the drill is in place, a support cushion is reinforced on a drill base by adopting a groined spiral pipe;
burying a protective cylinder, wherein the length of the protective cylinder is 4-6m, and welding the protective cylinder with a spiral pipe of a support pad;
the backfill material, the slurry pool and the slurry pump are arranged.
As a further technical scheme, when inclined holes and curved holes appear in construction, the treatment measures are as follows:
lengthening the length of the orifice steel casing to 4-6 m;
control of the boost stroke and slurry specific gravity: for clay, a lm small stroke is adopted in the range of 0-2 m, and a stroke of 1-2 m is adopted after the clay enters 2m; aiming at sandy soil and gravelly soil, adopting 2-3 m strokes; aiming at the rock stratum, a lm small stroke close stroke is adopted in the range of 0-2 m, and a 3-4 m stroke is adopted after entering 2m;
and backfilling the inclined rock face to be more than 0.5m by adopting C20 concrete, and drilling the inclined rock face after 72 hours until the hole position is corrected.
As a further technical scheme, when the construction is performed with the occurrence of hammer burying, hammer clamping and hammer dropping, the treatment measures are as follows:
firstly, clearing collapsed soil and stones in holes through hole clearing, loosening the periphery of an impact hammer through a method of punching and sucking punching slag in a gravel sand layer, and lifting out after loosening;
for the case of plum blossom Kong Kachui, loosening a steel wire rope and changing the angle of an impact hammer;
for the serious hole collapse buried hammer and the blocking hammer, adopting an impact hammer with larger diameter than the original diameter to remove soil and stone collapsed on the original hammer, and adopting a hollow hammer with large diameter to impact after contacting the original hammer to realize the separation of the original hammer and the hole wall;
in the salvaging process, mud circulation is normally carried out, and mud precipitation is avoided.
As a further technical scheme, when the hole collapse occurs in construction, the treatment measures are as follows:
adjusting the specific gravity, viscosity and colloid ratio of the slurry, drilling in saturated viscous soil and gravel sand layers, and strictly controlling the impact speed;
the orifice collapses, backfilling pile holes and removing the pile casing, and re-burying the pile casing for drilling; collapse occurs in the holes, the collapse position is confirmed, and clay is backfilled to 1-2 m above the collapse position; if the ground collapses and cracks, immediately backfilling to the orifice, and re-drilling;
ensuring the alignment of the plane position of the reinforcement cage and vertically installing and inserting pile holes;
quickly cleaning holes, and immediately entering the next working procedure for construction after the hole cleaning is completed;
the drilling stroke is tightly controlled.
As a further technical scheme, when pile body diameter shrinkage and diameter expansion occur in construction, the treatment measures are as follows:
backfilling the rubble clay, re-drilling and impacting to form a wall, and forming a stable hole wall;
the concentration and the surface height of the slurry are strictly controlled, so that the slurry in the hole is ensured to generate enough pressure on the hole wall;
after pore forming, pore cleaning and pile foundation pouring are completed rapidly, and the time for soaking the pore wall in low-concentration slurry is reduced;
ensuring the effective diameter of the hammer head of the impact hammer.
Compared with the prior art, the invention has the following advantages:
1. the method of the invention is used for karst pile foundation construction in karst basin, which can greatly reduce the probability of occurrence of inclined holes, buried drill, stuck drill, falling drill and collapse of karst pile foundation.
2. The method can be used for carrying out karst pile foundation construction on the karst basin, and can rapidly and effectively treat the karst pile foundation even if the conditions of inclined holes, buried drill, drill sticking, drill falling, collapse and the like of the karst pile foundation are met, and the construction progress is not influenced.
3. The construction steps are simple, and the construction efficiency is greatly improved.
Detailed Description
The present invention will be described in detail with reference to specific examples.
Examples
The railway passes through the karst section, part of karst is developed, and safety risks such as drill sticking, drill falling and collapse are easy to occur in karst pile foundation construction. The embodiment is described by the concrete condition of the method in the construction of the karst pile foundation of the right line Gao Minghe super bridge.
1 engineering overview
The right line Gao Minghe is a gray rock zone below the bridge site of the super-large bridge, the karst is shallow covered, the karst development intensity is graded to be medium-strong development, the karst development zone is mainly located in a seasonal variation zone, the vertical and horizontal karst morphological development is carried out, and the local karst cave buries deeply.
1.1 design case
The bridge site area cover layer mainly comprises: plain filled soil, sand layer, silt and powdery clay; the strata in the bridge site area mainly comprises: calcareous sandstone, carbonaceous limestone, brecciated limestone.
The karst bridge pile foundation is designed into a pile foundation, and the effective rock-socketed depth of the pile bottom is required to meet the design depth.
And (3) adopting a 1:1 stone clay backfilling treatment measure in the construction of a general karst section pile foundation with the karst cave height smaller than 3 m.
The closed type large karst cave with the height of more than 3m and the part of the large communicated karst cave are followed by adopting the steel pile casing, and the steel pile casing is followed to the position of 0.5m at the bottom of the karst cave.
1.2 drilling machine selection
The drilling machine adopts the impact drilling machine, so that the impact pore-forming geological applicability is strong, and meanwhile, the impact compaction effect is achieved on the foundation bearing capacity of the foundation.
1.3 pile foundation construction sequence
According to pile length and geological conditions revealed in pile foundation geological display diagrams, determining a construction sequence: pile foundations are constructed in a preferential manner from long to short, wherein pile shafts penetrate deeper, larger and more karst cave pile foundations.
2 concrete steps of karst pile foundation construction
2.1 preparation work
(1) Preparation for internal industry
And reasonably determining the pile foundation construction sequence according to the designed pile length and the geological data in the pier pile foundation geological display diagram.
(2) Preparation for field use
Each pier of the karst bridge is provided with 1 percussion drill. Before the drilling machine is in place, a 14m long and wide groined spiral pipe with the diameter of 300mm is adopted to carry out supporting and pad reinforcement on the base of the drilling machine, so that the drilling machine is prevented from sinking and tilting when a hole is collapsed.
Properly lengthened protective cylinders are buried, the length is generally 4-6m, and the protective cylinders are welded and connected with the supporting cushion spiral tube.
Before drilling, a certain amount of backfill materials (a piece of stone, a bagged clay and a proper amount of bagged cement) and 2 or 4D 220 slurry pumps of a large-capacity slurry pool are arranged.
2.2 karst pile foundation drilling
(1) Overburden drilling
(1) Plain filling soil
Adopting clay slurry to protect wall and drilling into the plain filling layer in a small stroke way to ensure that a hammer repeatedly builds a wall to compact the loose plain filling layer.
(2) Powdery clay
When entering and passing through the powdery clay layer, clay slurry wall protection and small stroke are adopted for drilling, so that stable compaction layers are formed by repeatedly forming walls at the stratum change positions.
(3) Sand layer
The thickness is less than 2m: when the sand layer (silt, fine sand, middle sand and coarse sand) drills, the cement slurry retaining wall and the small stroke are adopted for drilling, so that a stable mortar mud shell is easily formed between the cement slurry retaining wall and the sand layer, and the sand layer is ensured not to collapse due to the failure of the retaining wall during slurry replacement.
Thickness greater than 2m: when the sand layer (silt, fine sand, middle sand and coarse sand) drills, steel casing is adopted to drill through the sand layer. The steel pile casing should be pulled out when the follow-up depth is smaller than 7m, the steel pile casing is recycled, and the steel pile casing is used once when the follow-up depth is larger than 7 m.
(4) Silt layer
The layer thickness is less than 2m: when the silt layer drills, 1:1 piece of stone clay backfill treatment is adopted, so that an effective embedded guard ring is formed.
Thickness greater than 2m: when the silt layer drills, the steel casing is adopted to drill through the sand layer. The steel pile casing should be pulled out when the follow-up depth is smaller than 7m, the steel pile casing is recycled, and the steel pile casing is used once when the follow-up depth is larger than 7 m.
(2) Rock formation drilling
And in a general karst section with the karst cave height smaller than 3m, judging the karst cave volume and the transverse development condition according to the descending height and the speed of the liquid level of the slurry, and adopting a 1:1 stone clay filling compaction method. Backfilling the rubble clay to the karst cave top of 1.5m, and repeatedly drilling and backfilling until the slurry liquid level is stable and does not drop.
Closed large karst cave with height greater than 3m and partially large communicated karst cave: adopting a steel pile casing to follow, wherein the steel pile casing is followed to the height of 0.5m at the bottom of the karst cave, and the part with the multilayer karst cave is followed by adopting a double-layer steel pile casing.
2.3 karst pile foundation construction problem treatment method
(1) Inclined hole and curved hole
(1) The main reasons for this are: karst morphological development of underlying bedrock such as rock sprouts, gutters, fluid baths, erosion cracks, karst cave, etc., or inclined rock faces. In construction, the impact speed is too high, so that the impact hammer can slide along the rock surface to form inclined holes. If the construction of irregular vertical type hole gap is met, the impact hammer drills to the development direction of the hole gap to form a bent hole, and the hammer clamping accident occurs.
(2) Preventive measures:
when the rock formation is being drilled,
A. development characteristics such as stone buds, solution ditches, solution cracks, solution holes and the like and the burial depth of bedrock need to be particularly paid attention;
B. the impact speed and the impact frequency are reduced, and the low-frequency small-stroke drilling is used.
(3) The treatment measures are as follows:
the length of the orifice steel casing is lengthened to 4-6m, so that the guiding and collapse preventing effects are achieved.
Enhanced stroke and slurry specific gravity control. The clay (lm small stroke is adopted in the range of 0-2 m, and 1-2 m stroke is adopted after 2m is entered); sand and gravel (2-3 m stroke); the rock stratum (the small lm stroke is adopted for sealing in the range of 0-2 m, and the 3-4 m stroke is adopted after entering 2 m); the specific gravity of the slurry is strictly controlled, the pressure in the hole is balanced, and the hole collapse is prevented.
And backfilling the inclined rock face to be more than 0.5m by adopting C20 concrete, and drilling the inclined rock face after 72 hours until the hole position is corrected.
(2) Buried hammer, clamping hammer and dropping hammer
(1) The production reasons are mainly as follows: the sand layer of the covering layer is impacted and vibrated, and the retaining wall is easy to fail and collapse, so that a hammer is buried; or the impact hammer falls down after entering the vertical karst cave with larger hole gap; the thin rock stratum at the upper part of the solution cavity is impacted and vibrated to generate a falling block, so that the impact hammer is clamped; or because the specific gravity of the slurry is high, the impact hammer can be damaged in charging, and the impact hammer can not be lifted up due to the blocking hammer caused by the plum blossom holes.
Dropping the hammer: the steel wire rope, the steering ring, the steering sleeve, the joint and the like are broken, so that the impact hammer falls into the drill hole.
(2) Preventive measures:
A. according to stratum conditions, adopting corresponding stroke and impact speed;
B. the specific gravity of the slurry is strictly controlled, so that the slurry wall protection is prevented from losing efficacy and collapsing holes;
C. backfilling 1:1 piece of stone clay after drilling the karst cave, and filling the karst cave through close impact;
D. before each working, the positions of the steel wire rope, the connecting position and the like are safely checked.
(3) The treatment measures are as follows:
A. after the drilling, the specific condition of drilling is known, and the easy impact hammer cannot be pulled out forcibly;
B. firstly, clearing collapsed soil and stones in holes through hole clearing, loosening the periphery of an impact hammer through a method of punching and sucking punching slag in a gravel sand layer, and lifting out after loosening;
C. for the case of plum blossom Kong Kachui, loosening a steel wire rope and changing the angle of an impact hammer;
D. for the serious hole collapse buried hammer and the blocking hammer, adopting an impact hammer with larger diameter than the original diameter to remove soil and stone collapsed on the original hammer, and adopting a hollow hammer with large diameter to impact after contacting the original hammer to realize the separation of the original hammer and the hole wall;
E. in the salvaging process, mud circulation is normally carried out, so that mud precipitation is avoided;
(3) Hole collapse
(1) The production reasons are mainly as follows:
A. when the saturated viscous soil and sand layer are drilled, the specific gravity of the slurry is smaller, the quality of the slurry does not reach the standard, and the stability of the hole wall is reduced;
B. the pressure-bearing water exists in the hole, the water head height is insufficient, and the hydrostatic pressure is generated;
C. the penetration of the drilling medium suddenly encounters a karst cave and a solution gap, so that the liquid level of slurry in a hole suddenly drops;
D. the hole wall is impacted by the impact hammer during drilling or by the reinforcement cage during lowering;
E. the height of the water head in the hole is insufficient, and the slurry is not timely supplemented after slag is removed or water in the hole is lost.
(2) Preventive measures:
A. adopting corresponding slurry according to stratum conditions;
B. and (3) carrying out construction strictly according to the technical intersection requirements, and monitoring the slurry height and slurry quality in the hole.
C. On site storage of sufficient clay and platelets;
D. and (5) preparing spare mud with the volume of more than 10m3, and ensuring the normal operation of the mud pump.
E. Lengthening the protective cylinder to 4-6m to prevent the bottom of the protective cylinder of the covering layer from collapsing repeatedly. The bagged cement is thrown and filled, and the wall is made by repeatedly punching and tamping with small stroke.
F. The operators closely pay attention to the situation in the hole during drilling, and once the liquid level suddenly drops, measures for supplementing slurry and backfilling rubble clay are immediately taken, so that the wall protection is prevented from failing.
(3) The treatment measures are as follows:
A. adjusting the specific gravity, viscosity and colloid ratio of the slurry, drilling in saturated viscous soil and gravel sand layers, and strictly controlling the impact speed;
B. the orifice collapses, backfilling pile holes and removing the pile casing, and re-burying the pile casing for drilling; collapse occurs in the holes, the collapse position is confirmed, and clay is backfilled to 1-2 m above the collapse position; if the ground collapses and cracks, immediately backfilling to the orifice, and re-drilling;
C. ensuring the alignment of the plane position of the reinforcement cage and vertically installing and inserting pile holes;
D. quickly cleaning holes, and immediately entering the next working procedure for construction after the hole cleaning is completed;
E. the drilling stroke is tightly controlled.
(4) Pile body diameter-reducing and expanding
(1) The production reasons are mainly as follows: diameter reduction means that the diameter of the pile hole is reduced at a specific position, and diameter expansion means that the diameter of the pile hole is increased at a specific position, and the diameter expansion does not affect the usability of the pile. The slight diameter reduction is checked to meet the requirement of use, and the serious diameter reduction can not be treated.
(2) Preventive measures:
A. according to the stratum drilling condition, correspondingly adjusting the slurry performance;
B. controlling the drilling footage and stroke to drill in the saturated viscous soil and gravel sand layer;
C. when the effective diameter of the hammer head of the impact hammer is insufficient, the impact hammer is corrected in time.
(3) The treatment measures are as follows: upon impact with such a geotechnical formation,
A. backfilling the rubble clay, and drilling again to form a wall so as to form a stable hole wall.
B. The concentration of the slurry and the height of the slurry surface are strictly controlled, so that the slurry in the hole is ensured to generate enough pressure on the hole wall.
C. After pore-forming, the cleaning of pores and the pouring of pile foundations are completed rapidly, and the soaking time of pore walls in low-concentration slurry is reduced.
D. Ensuring the effective diameter of the hammer head of the impact hammer. Problems are found and corrected in time.
The foregoing description of the preferred embodiment of the invention is not intended to be limiting, but rather to cover all modifications, equivalents, and alternatives falling within the spirit and principles of the invention.
Claims (6)
1. The karst bridge pile foundation construction method is characterized by comprising the following steps of:
(1) Overburden drilling
Adopting clay mud to protect the wall and drilling a plain filling layer in a small stroke;
when entering and passing through the powdery clay layer, adopting clay slurry to protect the wall and carrying out drilling by a small stroke;
when the sand layer with the thickness less than 2m drills, adopting cement slurry to protect the wall and performing drilling with a small stroke;
when the sand layer with the thickness of more than 2m drills, the steel casing is adopted to drill through the sand layer in a follow-up way;
when a silt layer with the layer thickness less than 2m is drilled, 1:1 piece of stone clay backfill treatment is adopted;
when a silt layer with the thickness of more than 2m drills, a steel casing is adopted to drill through the sand layer;
(2) Rock formation drilling
Backfilling the stone clay to the karst cave top of 1.5m by adopting a 1:1 stone clay filling compaction method in a karst region with the karst cave height of less than 3m, and repeatedly drilling and backfilling until the slurry liquid level is stable and does not drop;
and (3) adopting a steel pile casing to follow up at the closed karst cave or the communicated karst cave with the height of more than 3m, wherein the steel pile casing is followed up to the height of 0.5m at the bottom of the karst cave, and adopting a double-layer steel pile casing to follow up at the pile position with the multilayer karst cave.
2. The karst bridge pile foundation construction method according to claim 1, characterized in that the construction method comprises the preparation work before construction:
(1) Preparation for internal industry
Designing pile length and geological data in the pier pile foundation geological display diagram to determine the pile foundation construction sequence;
(2) Preparation for field use
Each pier of the karst bridge is provided with 1 percussion drill, and before the drill is in place, a support cushion is reinforced on a drill base by adopting a groined spiral pipe;
burying a protective cylinder, wherein the length of the protective cylinder is 4-6m, and welding the protective cylinder with a spiral pipe of a support pad;
the backfill material, the slurry pool and the slurry pump are arranged.
3. The karst bridge pile foundation construction method according to claim 1, wherein when inclined holes and curved holes appear in the construction, the treatment measures are as follows:
lengthening the length of the orifice steel casing to 4-6 m;
control of the boost stroke and slurry specific gravity: for clay, a lm small stroke is adopted in the range of 0-2 m, and a stroke of 1-2 m is adopted after the clay enters 2m; aiming at sandy soil and gravelly soil, adopting 2-3 m strokes; aiming at the rock stratum, a lm small stroke close stroke is adopted in the range of 0-2 m, and a 3-4 m stroke is adopted after entering 2m;
and backfilling the inclined rock face to be more than 0.5m by adopting C20 concrete, and drilling the inclined rock face after 72 hours until the hole position is corrected.
4. The karst bridge pile foundation construction method according to claim 1, wherein when the construction is performed with a buried hammer, a stuck hammer or a drop hammer, the treatment measures are as follows:
firstly, clearing collapsed soil and stones in holes through hole clearing, loosening the periphery of an impact hammer through a method of punching and sucking punching slag in a gravel sand layer, and lifting out after loosening;
for the case of plum blossom Kong Kachui, loosening a steel wire rope and changing the angle of an impact hammer;
for the serious hole collapse buried hammer and the blocking hammer, adopting an impact hammer with larger diameter than the original diameter to remove soil and stone collapsed on the original hammer, and adopting a hollow hammer with large diameter to impact after contacting the original hammer to realize the separation of the original hammer and the hole wall;
in the salvaging process, mud circulation is normally carried out, and mud precipitation is avoided.
5. The karst bridge pile foundation construction method according to claim 1, wherein when a collapse hole occurs in the construction, the treatment measures are as follows:
adjusting the specific gravity, viscosity and colloid ratio of the slurry, drilling in saturated viscous soil and gravel sand layers, and strictly controlling the impact speed;
the orifice collapses, backfilling pile holes and removing the pile casing, and re-burying the pile casing for drilling; collapse occurs in the holes, the collapse position is confirmed, and clay is backfilled to 1-2 m above the collapse position; if the ground collapses and cracks, immediately backfilling to the orifice, and re-drilling;
ensuring the alignment of the plane position of the reinforcement cage and vertically installing and inserting pile holes;
quickly cleaning holes, and immediately entering the next working procedure for construction after the hole cleaning is completed;
the drilling stroke is tightly controlled.
6. The karst bridge pile foundation construction method of claim 1, wherein when pile body diameter shrinkage and expansion occur in construction, the treatment measures are as follows:
backfilling the rubble clay, re-drilling and impacting to form a wall, and forming a stable hole wall;
the concentration and the surface height of the slurry are strictly controlled, so that the slurry in the hole is ensured to generate enough pressure on the hole wall;
after pore forming, pore cleaning and pile foundation pouring are completed rapidly, and the time for soaking the pore wall in low-concentration slurry is reduced;
ensuring the effective diameter of the hammer head of the impact hammer.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN202311122147.3A CN117166515A (en) | 2023-09-01 | 2023-09-01 | Karst bridge pile foundation construction method |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202311122147.3A CN117166515A (en) | 2023-09-01 | 2023-09-01 | Karst bridge pile foundation construction method |
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| CN117166515A true CN117166515A (en) | 2023-12-05 |
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| CN202311122147.3A Pending CN117166515A (en) | 2023-09-01 | 2023-09-01 | Karst bridge pile foundation construction method |
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2023
- 2023-09-01 CN CN202311122147.3A patent/CN117166515A/en active Pending
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