CN111851276B - Pier enlarged foundation reinforcing structure and construction method thereof - Google Patents
Pier enlarged foundation reinforcing structure and construction method thereof Download PDFInfo
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- CN111851276B CN111851276B CN202010840993.9A CN202010840993A CN111851276B CN 111851276 B CN111851276 B CN 111851276B CN 202010840993 A CN202010840993 A CN 202010840993A CN 111851276 B CN111851276 B CN 111851276B
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- 230000003014 reinforcing effect Effects 0.000 title claims abstract description 79
- 238000010276 construction Methods 0.000 title claims abstract description 33
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 79
- 239000004567 concrete Substances 0.000 claims abstract description 71
- 230000002787 reinforcement Effects 0.000 claims abstract description 40
- 239000007788 liquid Substances 0.000 claims abstract description 33
- 239000011800 void material Substances 0.000 claims abstract description 21
- 239000011148 porous material Substances 0.000 claims abstract description 20
- 239000004568 cement Substances 0.000 claims description 27
- 239000002002 slurry Substances 0.000 claims description 26
- 235000019353 potassium silicate Nutrition 0.000 claims description 25
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 claims description 25
- 238000002347 injection Methods 0.000 claims description 22
- 239000007924 injection Substances 0.000 claims description 22
- 230000009471 action Effects 0.000 claims description 9
- 238000011144 upstream manufacturing Methods 0.000 claims description 5
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- 230000006641 stabilisation Effects 0.000 claims 7
- 238000011105 stabilization Methods 0.000 claims 7
- 238000007711 solidification Methods 0.000 abstract description 3
- 230000008023 solidification Effects 0.000 abstract description 3
- 238000000034 method Methods 0.000 description 21
- 238000011049 filling Methods 0.000 description 8
- 230000008569 process Effects 0.000 description 7
- 238000001514 detection method Methods 0.000 description 6
- 239000002689 soil Substances 0.000 description 6
- 238000009991 scouring Methods 0.000 description 5
- 230000007774 longterm Effects 0.000 description 3
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- 229910000831 Steel Inorganic materials 0.000 description 2
- 238000005553 drilling Methods 0.000 description 2
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- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000005056 compaction Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
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- 239000011150 reinforced concrete Substances 0.000 description 1
- 239000011435 rock Substances 0.000 description 1
- 238000007788 roughening Methods 0.000 description 1
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- 239000004575 stone Substances 0.000 description 1
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Classifications
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- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01D—CONSTRUCTION OF BRIDGES, ELEVATED ROADWAYS OR VIADUCTS; ASSEMBLY OF BRIDGES
- E01D19/00—Structural or constructional details of bridges
- E01D19/02—Piers; Abutments ; Protecting same against drifting ice
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- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01D—CONSTRUCTION OF BRIDGES, ELEVATED ROADWAYS OR VIADUCTS; ASSEMBLY OF BRIDGES
- E01D22/00—Methods or apparatus for repairing or strengthening existing bridges ; Methods or apparatus for dismantling bridges
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D27/00—Foundations as substructures
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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
- E02D37/00—Repair of damaged foundations or foundation structures
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Abstract
The invention discloses a pier expansion foundation reinforcing structure and a construction method thereof, wherein a concrete reinforcing layer and a water interception wall play a role in protecting an expansion foundation and a foundation around the expansion foundation, so that river scour of the bridge pier foundation is avoided, and meanwhile, the area of the original expansion foundation is increased, so that the bearing capacity of a new foundation is higher; the multiple guide pipes are like a reinforcement cage in concrete, play a role in connecting a foundation, expanding the foundation and a concrete reinforcing layer, further improve the bearing capacity of the original expanded foundation, and can be filled with grouting liquid through the guide pipes, the grouting liquid is diffused in the void part and/or the foundation pore to form a netlike solidification body, the void part, the foundation pore and the interface of a new structure and an old structure are filled, the new structure and the old structure form a whole, the bearing capacity and the durability of the reinforcing structure are further improved greatly, and meanwhile, the problem that the conventional reinforcing structure is uneven in stress due to interface stripping is solved effectively.
Description
Technical Field
The invention belongs to the technical field of bridge engineering, and particularly relates to a pier enlarged foundation reinforcing structure and a construction method thereof.
Background
An enlarged foundation is a form of foundation from which loads from piers or abutments and superstructure are transferred directly to a shallower supporting foundation, also known as an open cut enlarged foundation or shallow foundation. The foundation is larger than the contact area of the pile foundation and the soil body, so that the acting force of the unit area on the soil body is smaller, the requirement on the soil layer strength is low, the buried depth is shallower, and the foundation has the characteristics of simple structure form, simple construction and low cost, and is suitable for geological conditions of very deep or very shallow buried depth of rock stratum. The method has wide application in the foundation structure of the middle-small span bridge, in particular to the stone arch bridge.
Under the long-term actions of service environments such as strong winds, earthquakes and heavy traffic, potential safety hazards generally exist in bridge expansion foundations. The existing bridge detection result shows that partial bridge abutment foundations have the phenomenon of void under the river scouring action, and the distance from the ground line of the bridge abutment river bed to the foundation bottom is overlarge, so that the safety of the upper structure is affected. Bridge pier foundation void is a common disease in bridge engineering, is common on bridge pier foundations of arch bridges and small and medium span bridges built in the last century, and needs detection and reinforcement treatment.
The pier expanding foundation reinforcement method mainly comprises three types: the weak member reinforcement method, the auxiliary member addition method and the novel structural system method can refer to the ' blue line sleeve water river No. 2 bridge pier foundation reinforcement research ' of the West south traffic university ' graduate paper. The most common and convenient method is a weak member reinforcement method, namely the rigidity and bearing capacity of the original foundation are increased in a mode of increasing the cross-sectional area of the member, but the reinforced integral stress characteristic and the reinforced earthquake resistance are poor, and the literature of 'in-service bridge foundation expansion bearing capacity evaluation method research' can be referred to Tao Cheng and the like. Patent literature with the name of bridge reinforcement foundation and bridge and the authorized bulletin number of CN203701129U adopts a scheme that the lower end of a micro pile drilling hole penetrates through the bottom plate of the enlarged foundation, but pile foundation drilling period is long and cost is relatively high.
At present, aiming at the problem of local scouring of an enlarged foundation of a pier, the general reinforcement treatment method comprises the following steps: the expansion of foundation slab area, the supplement of pile foundation method and concrete sleeve-collar method, high-pressure jet grouting method, etc. can refer to Guo Zhan equally proposed test and study of shallow foundation reinforcement. The reinforcing construction by adopting the foundation slab area expanding method is quite common, but in the use process after the reinforcing, the bonding performance between a newly added foundation structure and the existing expanding foundation and the foundation can be gradually degraded, even a peeling phenomenon occurs, and the reinforcing effect of the foundation slab area expanding method is difficult to embody after long-term use. To solve this problem, engineers typically roughen and brush clean the original foundation, and add a layer of high strength grade cement paste or concrete interface agent to increase the binding power of the new and old concrete foundations. However, in a long-term use state, the structural interface peeling phenomenon still exists, and the durability of the reinforcing effect is insufficient.
Disclosure of Invention
The invention aims to provide a pier expansion foundation reinforcing structure and a construction method thereof, which are used for solving the problems of poor reinforcing effect, insufficient durability and the like caused by degradation of bonding performance and even stripping between a newly added foundation structure and an existing expansion foundation and a foundation in the prior art.
One or more of the above objects are solved by the solutions of the independent claims of the present invention.
The invention solves the technical problems by the following technical scheme: the bridge pier expansion foundation reinforcing structure comprises a bridge pier and an expansion foundation arranged below the bridge pier, and is characterized in that a concrete reinforcing layer is arranged above the expansion foundation or the expansion foundation and the foundation, and the concrete reinforcing layer is arranged around the periphery of the bridge pier; a water interception wall is arranged along the periphery of the concrete reinforcing layer; and a plurality of guide pipes are arranged on the concrete reinforcing layer, and extend into the foundation through the concrete reinforcing layer and/or the concrete reinforcing layer and the enlarged foundation.
According to the bridge pier expansion foundation reinforcing structure, the concrete reinforcing layer and the water interception wall are connected to form the annular structure, the annular structure surrounds the expansion foundation, so that the expansion foundation and the foundation around the expansion foundation are protected, the river is prevented from scouring the bridge pier foundation, the number of bridge pier foundation void parts is reduced, the area of the original expansion foundation is increased, and the bearing capacity of a new foundation is higher; the multiple guide pipes are like a reinforcement cage in concrete, play a role of connecting a foundation, expanding the foundation and a concrete reinforcing layer, further improve the bearing capacity of the original expanded foundation, and can be injected with grouting liquid through the guide pipes, the grouting liquid is diffused in the void part and/or the foundation pore to form a netlike solidification body, the void part, the foundation pore and the interface of a new structure and an old structure are filled, the stability of the whole reinforcing structure is ensured, the cohesiveness between the new structure and the old structure is ensured, the new structure and the old structure form a whole, the bearing capacity and the durability of the reinforcing structure are further improved greatly, and meanwhile, the problem that the conventional reinforcing structure is uneven in stress due to interface stripping is effectively solved.
Further, a plurality of the guide pipes are annularly arranged in a plurality of circles, and one circle of guide pipe is corresponding to each layer of step of the enlarged foundation. The grouting holes are uniformly distributed through the multi-ring annular arrangement, so that grouting liquid can be uniformly pressed into the reinforcing structure and/or the foundation, the full filling of the void part and/or the foundation hole is realized, the problem of filling leakage or filling deficiency is avoided, and the stability of the reinforcing structure is improved.
Further, the distance between the adjacent conduits in the same circle is smaller than 1.8m, the denser the conduits are, the more can ensure that all the void parts or foundation pores are filled with slurry, but the distance between the adjacent conduits in the same circle is smaller than 1.8m in consideration of construction requirements of construction machines and the effective range of the slurry addition of the conduits is about 0.5-1.8 m.
Preferably, the diameter of the conduit is 60-80 mm, the length of the conduit is 5-7 m, and the length of the conduit part penetrating through the expansion foundation and located in the foundation is 2-3 m.
Further, the guide pipe passing through the expansion foundation is arranged parallel to the bridge pier, and the bottom end of the guide pipe not passing through the expansion foundation is obliquely arranged inwards; preferably, the included angle between the obliquely arranged guide pipe and the pier is 45-60 degrees.
The guide pipe that the slope set up extends to the foundation of expanding the foundation bottom in, is convenient for fill the void position or the foundation hole of expanding the foundation bottom, has improved pier bottom foundation structure's bearing capacity, is favorable to improving the steadiness of pier more.
Further, the longitudinal section of the water interception wall is trapezoid; preferably, the gradient of the trapezoid is 1:0.3. the trapezoid water interception wall can intercept water flow more effectively, and impact force of the water flow on a foundation structure is reduced.
The invention also provides a construction method of the pier enlarged foundation reinforcing structure, which comprises the following steps:
Arranging a plurality of guide pipes around the bridge pier, wherein the bottom ends of the guide pipes extend into the foundation and/or extend into the foundation through the enlarged foundation;
injecting grouting liquid into the guide pipe at low pressure, and enabling the grouting liquid to flow into the foundation under the action of pressure so as to fill the void part and/or the foundation pores;
pouring concrete at the periphery of the enlarged foundation and the pier to form an annular water interception wall;
the enlarged foundation is processed, and concrete is poured on the enlarged foundation between the cut-off wall and the bridge pier or above the enlarged foundation and the foundation to form a concrete reinforcing layer;
And injecting the grouting liquid into the guide pipe at high pressure, and allowing the grouting liquid to flow into the foundation under the action of pressure so as to fill the gap between the concrete reinforcing layer and the enlarged foundation.
According to the reinforcement method, through twice grouting liquid injection, the void part and the foundation pore are filled in the first low-pressure injection, grouting reinforcement is realized, the stability in the construction process of the concrete reinforcement layer is ensured, but after the construction of the concrete reinforcement layer, the pore still exists at the interface between the concrete reinforcement layer and the enlarged foundation, and the second high-pressure injection is needed to be carried out to fill the pores, so that the new and old reinforcement structures are integrated, the stability and the cohesiveness of the whole reinforcement structure are improved, and the bearing capacity and the durability of the reinforcement structure are improved.
Further, a plurality of the guide pipes are annularly arranged in a plurality of circles, and one circle of guide pipe is corresponding to each layer of step of the enlarged foundation.
Further, the guide pipe passing through the expansion foundation is arranged parallel to the bridge pier, and the bottom end of the guide pipe not passing through the expansion foundation is obliquely arranged inwards; preferably, the included angle between the obliquely arranged guide pipe and the pier is 45-60 degrees.
Further, the grouting liquid is cement water glass slurry, and the cement water glass slurry is prepared from cement slurry and water glass in a volume ratio of 1:0.05-1:0.1; the cement paste has a water cement ratio of 1:0.5-1:1, the modulus of the water glass is 2.8, and the water glass is 35 Baume degree water glass.
Further, the pressure during low pressure injection is 0.3-0.5 MPa, and the pressure during high pressure injection is 1.5MPa.
Further, at the time of the high-pressure injection, the injection sequence is: a conduit adjacent to the previous cutoff wall, a conduit adjacent to the next cutoff wall, and a conduit adjacent to the last rear cutoff wall;
The water interception walls comprise front water interception walls, rear water interception walls and side water interception walls, the front water interception walls are water interception walls which are positioned on the upstream face along the water flow direction, the rear water interception walls are water interception walls which are positioned on the downstream face along the water flow direction, and the side water interception walls are water interception walls on the other two sides.
Advantageous effects
Compared with the prior art, the pier expansion foundation reinforcing structure and the construction method thereof provided by the invention have the advantages that the concrete reinforcing layer and the water interception wall play a role in protecting the expansion foundation and the foundation around the expansion foundation, so that the river is prevented from scouring the bridge pier foundation, the number of the bridge pier foundation void parts is reduced, the area of the original expansion foundation is increased, and the bearing capacity of the new foundation is higher; the multiple guide pipes are like a reinforcement cage in concrete, play a role of connecting a foundation, expanding the foundation and a concrete reinforcing layer, further improve the bearing capacity of the original expanded foundation, and can be injected with grouting liquid through the guide pipes, the grouting liquid is diffused in the void part and/or the foundation pore to form a netlike solidification body, the void part, the foundation pore and the interface of a new structure and an old structure are filled, the stability of the whole reinforcing structure is ensured, the cohesiveness between the new structure and the old structure is ensured, the new structure and the old structure form a whole, the bearing capacity and the durability of the reinforcing structure are further improved greatly, and meanwhile, the problem that the conventional reinforcing structure is uneven in stress due to interface stripping is effectively solved.
Drawings
In order to more clearly illustrate the technical solutions of the present invention, the drawings that are needed in the description of the embodiments will be briefly described below, it being obvious that the drawing in the description below is only one embodiment of the present invention, and that other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a front view of an enlarged foundation reinforcing structure for piers according to embodiment 1 of the present invention;
FIG. 2 is a top view of an enlarged pier foundation reinforcement structure in accordance with the present invention in embodiment 1;
FIG. 3 is a flow chart of a construction method of an enlarged foundation reinforcement structure for piers in embodiment 1 of the invention;
FIG. 4 is a front view of the enlarged foundation reinforcing structure of the pier according to embodiment 2 of the present invention, wherein numerals in FIG. 4 each represent dimensions in cm;
FIG. 5 is a top view of the enlarged foundation reinforcing structure of the pier according to embodiment 2 of the present invention, wherein numerals in FIG. 5 each represent dimensions in cm;
Wherein, 1-pier, 2-pipe, 3-water interception wall, 31-front water interception wall, 32-back water interception wall, 33-side water interception wall, 4-concrete reinforcement layer, 5-enlarged foundation, 6-foundation, 7-ground line, A is the water flow direction.
Detailed Description
The following description of the embodiments of the present invention will be made more apparent and fully by reference to the accompanying drawings, in which it is shown, however, only some, but not all embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Example 1
As shown in fig. 1 and 2, the pier expansion foundation reinforcement structure provided by the invention comprises a pier 1 and an expansion foundation 5 arranged below the pier 1, wherein a concrete reinforcement layer 4 is arranged above the expansion foundation 5 and a foundation 6 (or the concrete reinforcement layer 4 is arranged above the expansion foundation 5), and the concrete reinforcement layer 4 is arranged around the periphery of the pier 1; the water interception walls 3,3 are arranged along the periphery of the concrete reinforcing layer 4 and comprise a front water interception wall 31, a rear water interception wall 32 and side water interception walls 33, wherein the front water interception wall 31 is the water interception wall which is positioned on the upstream surface along the water flow direction, the rear water interception wall 32 is the water interception wall which is positioned on the downstream surface along the water flow direction, and the side water interception walls 33 are the water interception walls on the other two sides; the concrete reinforcement layer 4 is provided with a plurality of guide pipes 2, the plurality of guide pipes 2 penetrate through the concrete reinforcement layer 4 and/or the concrete reinforcement layer 4 and the enlarged foundation 5 to extend into the foundation 6, namely, three conditions exist, wherein the first condition is that part of the guide pipes 2 penetrate through the concrete reinforcement layer 4 and then directly extend into the foundation 6, and part of the guide pipes 2 penetrate through the concrete reinforcement layer 4 and the enlarged foundation 5 and then extend into the foundation 6; the second is that all the pipes 2 extend directly into the foundation 6 after passing through the concrete reinforcing layer 4 only; the third is that all the pipes 3 extend into the foundation 6 after passing through the concrete reinforcing layer 4 and expanding the foundation 5.
As shown in fig. 2, the plurality of pipes 2 are annularly arranged in a plurality of circles, one circle of pipes 2 is corresponding to each layer of steps of the enlarged foundation 5 (each layer of steps corresponds to one circle of pipes 2 in the enlarged foundation 5 in fig. 2), the number of circles of the pipes 2 is generally 4-6, in this embodiment, 4 circles of pipes 2 are provided, two circles of pipes 2 penetrate through the concrete reinforcing layer 4 and the enlarged foundation 5, and the other two circles of pipes 2 only penetrate through the concrete reinforcing layer 4. The multi-ring annular arrangement can enable grouting holes (namely guide pipes) to be uniformly distributed, so that grouting liquid can be uniformly pressed into the reinforcing structure and/or the foundation 6, the full filling of the void part and/or the foundation pore is realized, the problem of filling leakage or filling incompleteness is avoided, and the stability of the reinforcing structure is improved.
As shown in fig. 1, the conduit 2 passing through the enlarged footing 5 is disposed parallel to the bridge pier 1 (or perpendicular to the enlarged footing 5), and the bottom end of the conduit 2 not passing through the enlarged footing 5 is disposed obliquely inward (i.e., obliquely toward the enlarged footing 5); the included angle between the obliquely arranged guide pipe 2 and the pier 1 is 45-60 degrees. The obliquely arranged guide pipe 2 extends into the foundation 6 at the bottom of the enlarged foundation 5, so that the void part or foundation pore at the bottom of the enlarged foundation is filled conveniently, the bearing capacity of the foundation structure at the bottom of the pier is improved, and the stability of the pier is improved more conveniently.
In this embodiment, the conduit 2 is a steel pipe, the diameter of the conduit 2 is 60-80 mm, preferably 75mm, the length is 5-7 m, and the length of the portion of the conduit 2 passing through the enlarged foundation 5 and located in the foundation 6 (i.e. the depth of the conduit 2 located at the bottom of the enlarged foundation 5) is 2-3 m. The denser the conduit 2 is, the more can ensure that all the void parts or foundation pores are filled with slurry, but the spacing between adjacent conduits 2 on the same ring is less than 1.8m in consideration of the construction requirements of construction machines and the slurry adding effective range of the conduit 2 is about 0.5-1.8 m.
As shown in fig. 1, a front cutoff wall 31, a rear cutoff wall 32, and a side cutoff wall 33 form an annular cutoff wall 3, the cutoff wall 3 has a trapezoid shape in longitudinal section, and the gradient of the trapezoid is 1:0.3. the trapezoid water interception wall can intercept water flow more effectively, and impact force of the water flow on a foundation structure is reduced. The height of the water interception wall is consistent with the height of the enlarged foundation.
As shown in fig. 3, the present invention also provides a construction method of the pier enlarged foundation reinforcing structure, comprising the following steps:
(1) Preparing.
The enlarged foundation 5 is measured and lofted, cofferdam and drainage construction are carried out, drainage ditches and collector wells are arranged on the inner side of the cofferdam, the reinforcement construction process is ensured not to be influenced by river water scouring, and water seepage is reduced.
(2) Arranging a plurality of guide pipes 2 around the bridge pier 1, wherein the bottom ends of the guide pipes 2 extend into the foundation 6 or extend into the foundation 6 through the enlarged foundation 5, namely, three conditions exist, namely, part of the guide pipes 2 directly extend into the foundation 6 after passing through the concrete reinforcing layer 4, and part of the guide pipes 2 extend into the foundation 6 after passing through the concrete reinforcing layer 4 and the enlarged foundation 5; the second is that all the pipes 2 extend directly into the foundation 6 after passing through the concrete reinforcing layer 4 only; the third is that all the pipes 3 extend into the foundation 6 after passing through the concrete reinforcing layer 4 and expanding the foundation 5.
As shown in fig. 1 and 2, the plurality of pipes 2 are arranged in a multi-circle annular shape, and each circle of pipes 2 is corresponding to each layer of steps of the enlarged foundation 5. The guide pipe 2 passing through the enlarged foundation 5 is arranged parallel to the bridge pier 1, the bottom end of the guide pipe 2 not passing through the enlarged foundation 5 is obliquely arranged inwards, and an included angle between the obliquely arranged guide pipe 2 and the bridge pier 1 is 45-60 degrees. The guide pipe 2 is a steel pipe, the diameter of the guide pipe 2 is 60-80 mm, preferably 75mm, and the length is 5-7 m.
(3) And (5) preparing grouting liquid.
The grouting liquid is cement water glass slurry, the cement water glass slurry is prepared by using ordinary Portland cement and 40 Baume water glass as main pulping materials, the 40 Baume water glass is diluted to 35 Baume, the modulus of the water glass is 2.8, the ordinary Portland cement is diluted to prepare cement slurry, the cement slurry water-cement ratio is 1:0.5-1:1, and the cement water glass slurry is prepared by cement slurry and water glass with the volume ratio of 1:0.05-1:0.1. The cement water glass slurry overcomes the defects of long setting time, difficult control, low calculus rate under the condition of flowing water and the like of single-liquid cement slurry, improves the effect of cement grouting, expands the range of cement grouting and can achieve the aim of quick plugging.
(4) Aiming at the problem of loosening the foundation 6 at the bottom of the enlarged foundation 5, cement water glass slurry is injected into the guide pipe 2 at low pressure through the grouting pipe, the cement water glass slurry in the guide pipe 2 flows into the foundation 6 under the action of the low pressure, the cement water glass slurry in the foundation 6 forms a slurry bubble body, an extremely complex stress system is generated in the foundation 6, the cement water glass slurry can be obviously reinforced within the range of 0.5-1.8 m from the slurry bubble body, and the void part and/or the foundation pore are filled.
In this embodiment, the pressure at the time of low pressure injection is 0.3 to 0.5MPa, and injection is stopped when the grouting liquid emerges from the top of the conduit 2. According to the hardness degree of the foundation 6 soil layers, grouting can be performed in modes of filling, infiltration, compaction, splitting and the like, and grouting reinforcement is performed in 2-3 m of the foundation of the pier 1. The grouting pipe is a hose, can be inserted into and pulled out of the guide pipe 2, can also move in the guide pipe 2, and is 30-50 cm away from the bottom end of the guide pipe 2 when grouting (namely grouting cement-water glass slurry).
(5) The grouting liquid in the conduit 2 is removed for the next grouting.
(6) And casting concrete at the periphery of the enlarged foundation 5 and the bridge pier 1 to form an annular water interception wall.
As shown in fig. 2, the water interception wall 3 includes a front water interception wall 31, a rear water interception wall 32, and side water interception walls 33, wherein the front water interception wall 31 is a water interception wall located on the upstream surface in the water flow direction, the rear water interception wall 32 is a water interception wall located on the downstream surface in the water flow direction, and the side water interception walls 33 are water interception walls on the other two sides.
(7) And (3) roughening and brushing the enlarged foundation 5, and pouring concrete above the enlarged foundation 5 and the foundation 6 between the cut-off wall and the bridge pier 1 to form a concrete reinforcing layer 4.
The height of the concrete reinforcing layer 4 is determined according to the damage degree of the enlarged foundation 5 so as to meet the designed strength requirement, and the height of the concrete reinforcing layer 4 is generally 1-2 m. When pouring the concrete reinforcing layer 4, guarantee that the top of pipe 2 exceeds the concrete reinforcing layer 4 to avoid the concrete to block up pipe 2, be unfavorable for subsequent injection of slip casting liquid.
(8) Aiming at the bonding problem among the concrete reinforcing layer 4, the enlarged foundation 5 and the foundation 6, grouting liquid is injected into the guide pipe 2 at high pressure through the grouting pipe, and the grouting liquid flows into the foundation 6 under the action of high pressure and permeates into the foundation 6 between the concrete reinforcing layer 4 and the enlarged foundation 5, so that the filling of the pores between the concrete reinforcing layer 4 and the enlarged foundation 5 is realized.
In this example, the pressure at the time of high-pressure injection was 1.5MPa. The injection of the grouting liquid is generally performed in a sequence of firstly outer injection and then inner injection, but under the condition of water flow, the grouting liquid starts to be injected from the end with higher water head, because the grouting liquid has a downward migration phenomenon, namely flows from the place with higher water head to the place with lower water head, and the grouting is ensured to be full under the action of the water flow by firstly injecting from the end with higher water head. Thus, in this embodiment, the implantation sequence is: the pipes 2 near the front cutoff wall 31, the pipes 2 near the rear cutoff wall 33, and finally the pipes 2 near the rear cutoff wall 32, and the synchronous injection is ensured as much as possible (for example, when the pipes 2 near the front cutoff wall 31 are injected, the synchronous injection of several pipes 2 near the front cutoff wall 31 is ensured as much as possible).
During high-pressure injection, parameter changes in the grouting process, such as grouting amount, grouting range, grouting pressure, slurry gel time and the like, can be monitored in a key way, and the grouting amount can be adjusted in time according to the conditions of on-site grouting amount, grouting pressure, surface grouting distance and the like. For example, the initial grouting has large pumping pressure and small suction amount, or the situation of sudden occurrence in the grouting process, the grouting should be stopped, and the grouting is performed after the guide pipe 2 is cleaned. The grouting is ended when one of the following occurs: a. continuing grouting for 10min when the injection rate is smaller than 1L/min; b. when the grouting point has a grouting range of 3-5 m; c. the grouting amount of the single conduit 2 reaches 1.5 to 2.0 times of the average grouting amount.
(9) And (3) detecting the compactness of the reinforced structure by adopting high-frequency radar waves, returning to the step (8) if the structure pores are not compact, and carrying out the step (10) if the structure pores are compact.
(10) The conduit 2 above the surface of the concrete reinforcing layer 4 is cut off, the conduit 2 below the surface is reserved, and the new-old foundation (namely the concrete reinforcing layer 4 and the enlarged foundation 5) and the foundation 6 are stressed together under the bonding action of grouting liquid to form a reinforcing structure of the pier enlarged foundation.
The construction method adopts secondary grouting, the stability of the foundation soil layer is ensured by the primary low-pressure grouting, the subsequent concrete reinforcing layer 4 is stable in the pouring process, the concrete reinforcing layer 4, the enlarged foundation 5, the foundation soil layer and the reserved conduit 2 are mutually bonded to form a reinforcing structure whole by the secondary high-pressure grouting, a structure stress system is formed, the bearing capacity and the reliability of the enlarged foundation reinforcing structure are improved, and the construction is convenient.
Example 2
In the Longshan county of Hunan Xiangxi of Hunan province of the power station bridge of the Bay, the upper structure is a reinforced concrete hyperbolic arch bridge with the thickness of 4 multiplied by 39m and 1 multiplied by 25m, and the pier foundation is an enlarged foundation. The special inspection of the bridge by engineering detection units finds that the wall masonry mortar of the bridge pier falls off, local hollows are formed, and the foundation is flushed out. The pier expansion foundation reinforcing structure and the construction method thereof are adopted for reinforcing, a newly-built concrete structure (namely a concrete reinforcing layer and a water cut wall) adopts C30 materials, grouting liquid is cement water glass grouting liquid, and a reinforcing structure diagram is shown in fig. 4 and 5.
The bridge reinforcing structure is subjected to quality detection and monitoring measurement from 5 days of 7 in 2019 to 30 days of 9 in 2019. The 800M geological radar instrument is adopted to carry out quality detection on the reinforced structure of the enlarged foundation of all piers, and detection results show that the foundation is free from void, pores and the interface between new and old structures do not find incompact signals, thus showing that the reinforced structure has better integrity. In the foundation reinforcement construction and the construction process of paving the main arch bridge and the bridge deck of the upper structure, the plane sedimentation height difference of the pier foundation is less than 0.2mm, and the accumulated sedimentation amount is less than 1mm, which indicates that the stress of the enlarged foundation reinforcement structure is uniform during the full-bridge reinforcement construction period, and the bearing capacity is higher.
The foregoing disclosure is merely illustrative of specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art will readily recognize that changes and modifications are possible within the scope of the present invention.
Claims (8)
1. The pier expansion foundation reinforcement structure comprises a pier and an expansion foundation arranged below the pier, and is characterized in that: a concrete reinforcing layer is arranged above the enlarged foundation and the foundation, and the concrete reinforcing layer is arranged around the periphery of the pier; the water interception wall comprises a front water interception wall, a rear water interception wall and side water interception walls, wherein the front water interception wall is positioned on the upstream surface along the water flow direction, the rear water interception wall is positioned on the upstream surface along the water flow direction, and the side water interception walls are positioned on the other two sides; the concrete reinforcement layer is provided with a plurality of guide pipes, part of the guide pipes penetrate through the concrete reinforcement layer and then directly extend into the foundation, part of the guide pipes penetrate through the concrete reinforcement layer and the enlarged foundation and then extend into the foundation, the guide pipes penetrating through the enlarged foundation are parallel to the bridge piers, and the bottom ends of the guide pipes not penetrating through the enlarged foundation are obliquely arranged inwards; the plurality of guide pipes are annularly arranged in a plurality of circles, and each layer of step of the enlarged foundation is correspondingly provided with one circle of guide pipe; the construction method comprises the following steps:
Arranging a plurality of guide pipes around the bridge pier, wherein part of the guide pipes penetrate through the concrete reinforcing layer and then directly extend into the foundation, and part of the guide pipes penetrate through the concrete reinforcing layer and expand the foundation and then extend into the foundation;
injecting grouting liquid into the guide pipe at low pressure, and enabling the grouting liquid to flow into the foundation under the action of pressure so as to fill the void part and/or the foundation pores;
pouring concrete at the periphery of the enlarged foundation and the pier to form an annular water interception wall;
The enlarged foundation is treated, and concrete is poured above the enlarged foundation and the foundation between the cut-off wall and the bridge pier to form a concrete reinforcing layer;
injecting the grouting liquid into the guide pipe at high pressure, and allowing the grouting liquid to flow into the foundation under the action of pressure so as to fill the gap between the concrete reinforcing layer and the enlarged foundation; wherein, during the high pressure injection, the injection sequence is as follows: the duct near the previous cutoff, the duct near the next cutoff, and the duct near the last cutoff.
2. The pier expanding foundation stabilization structure construction method of claim 1, wherein: the spacing between adjacent conduits of the same turn is less than 1.8m.
3. The pier expanding foundation stabilization structure construction method of claim 2, wherein: the diameter of the conduit is 60-80 mm, the length of the conduit is 5-7 m, and the length of the conduit passing through the enlarged foundation and positioned in the foundation is 2-3 m.
4. The pier expanding foundation stabilization structure construction method of claim 1, wherein: the included angle between the obliquely arranged guide pipe and the pier is 45-60 degrees.
5. The pier expanding foundation stabilization structure construction method of any one of claims 1 to 4, wherein: the longitudinal section of the water interception wall is trapezoid.
6. The pier expanding foundation stabilization structure construction method of claim 5, wherein: the gradient of the trapezoid is 1:0.3.
7. The pier expanding foundation stabilization structure construction method of claim 1, wherein: the grouting liquid is cement water glass slurry, and the cement water glass slurry is prepared from cement slurry and water glass in a volume ratio of 1:0.05-1:0.1; the cement paste has a water cement ratio of 1:0.5-1:1, the modulus of the water glass is 2.8, and the water glass is 35 Baume degree water glass.
8. The pier expanding foundation stabilization structure construction method of claim 1, wherein: the pressure during low-pressure injection is 0.3-0.5 MPa, and the pressure during high-pressure injection is 1.5MPa.
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| CN114411690A (en) * | 2022-01-22 | 2022-04-29 | 郑州大学 | Grouting arrangement structure and method for rapid reinforcing and repairing of strip foundation |
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