CN111851276A - Pier enlarged foundation reinforcing structure and construction method thereof - Google Patents

Abstract

The invention discloses a pier enlarged foundation reinforcing structure and a construction method thereof.A concrete reinforcing layer and a cut-off wall play a role in protecting an enlarged foundation and a foundation around the enlarged foundation, so that a river is prevented from scouring a pier foundation, and the area of the original enlarged foundation is increased, so that the bearing capacity of a new foundation is higher; the multiple guide pipes are like a steel bar framework in concrete, play a role in connecting the foundation, expanding the foundation and a concrete reinforcing layer, further improve the bearing capacity of the original expanded foundation, 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 net-shaped solidified body, the void part, the foundation pore and the interface of the new-old structure are filled, the new-old structure forms a whole, the bearing capacity and the durability of the reinforced structure are further greatly improved, and meanwhile, the problem of uneven stress of the conventional reinforced structure caused by interface stripping is effectively solved.

Description

Pier enlarged foundation reinforcing structure and construction method thereof

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

The enlarged foundation is a foundation form in which a load transmitted from a pier or an abutment and a superstructure is directly transmitted to a shallow supporting foundation, and is also called an open cut enlarged foundation or a shallow foundation. The foundation is larger than the contact area between the pile foundation and the soil body, so that the acting force of unit area to 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, simple and convenient construction and low cost, and is suitable for geological conditions with very deep or very shallow buried depth of the rock stratum. The method has wide application in the foundation structure of medium and small span bridges, particularly stone arch bridges.

Under the long-term action of service environments such as strong wind, earthquake, heavy traffic and the like, potential safety hazards generally exist on the expanded foundation of the bridge. The existing bridge detection results show that the part of the bridge abutment foundation under the action of river scouring has a void phenomenon, and the distance from the ground line of the bridge pier and the riverbed to the bottom of the foundation is too large, so that the safety of the upper structure is influenced. The bridge pier foundation void is a common disease in bridge engineering, is common in bridge pier foundations of arch bridges built in the last century and bridges with medium and small span, and needs to be detected and reinforced urgently.

The pier expanding foundation strengthening method mainly comprises three types: weak component reinforcing method, auxiliary component adding method and novel structural system method refer to the university of southwest traffic university Master graduation article "blue green line river 2 bridge pier foundation reinforcing research". The most common and convenient method is a weak member reinforcing method, namely the rigidity and the bearing capacity of the original foundation are increased in a mode of increasing the section area of a member, but the integral stress characteristic and the seismic performance after reinforcement are poor, and the literature of 'evaluation method for bearing capacity of an in-service bridge expansion foundation' provided by pottery and honest and the like can be referred. The patent document with the granted publication number of CN203701129U and the name of bridge reinforcing foundation and bridge adopts the scheme that the lower end of the micro-pile drilling hole penetrates through the bottom plate of the enlarged foundation, but the pile foundation drilling period is long and the cost is relatively high.

At present, aiming at the problem of local scouring of an enlarged foundation of a pier, a general method for reinforcing the enlarged foundation of the pier comprises the following steps: the method for enlarging the area of the foundation slab, the method for supplementing the pile foundation, the method for hooping the concrete, the method for high-pressure jet grouting and the like can refer to the test and research on shallow foundation reinforcement proposed by Guoshei and the like. The method for enlarging the area of the foundation slab is commonly used for reinforcing construction, but in the use process after reinforcement, the bonding performance between a newly added foundation structure and the existing enlarged foundation and foundation can gradually degrade, even peeling occurs, and after long-term use, the reinforcement effect of the method for enlarging the area of the foundation slab is difficult to embody. In order to solve the problem, engineers generally roughen and scrub the original foundation, and add a new layer of high-strength grade cement paste or coat a concrete interface agent to increase the binding power of the new and old concrete foundations. However, in the long-term use state, the structure interface is still peeled off, and the durability of the reinforcing effect is insufficient.

Disclosure of Invention

The invention aims to provide a pier enlarged foundation reinforcing structure and a construction method thereof, and aims to solve the problems of poor reinforcing effect, insufficient durability and the like caused by degradation and even peeling of bonding performance between a newly added foundation structure and an existing enlarged foundation and foundation in the prior art.

One or more of the above objects are solved by the solution of the independent claims of the present invention.

The invention solves the technical problems through the following technical scheme: a pier expanded foundation reinforcing structure comprises a pier and an expanded foundation arranged below the pier, and is characterized in that a concrete reinforcing layer is arranged above the expanded foundation or the expanded foundation and a foundation, and the concrete reinforcing layer is arranged around the periphery of the 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 reinforcing structure for the enlarged pier foundation, the concrete reinforcing layer and the cut-off wall are connected to form the annular structure, the annular structure surrounds the enlarged foundation, the enlarged foundation and the foundation periphery are protected, a river is prevented from washing the pier foundation, the number of the bridge pier foundation void parts is reduced, the area of the original enlarged foundation is increased, and the bearing capacity of a new foundation is higher; the plurality of guide pipes are like a steel bar framework 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, can be injected with grouting liquid through the guide pipes, the grouting liquid is diffused in a void part and/or a foundation pore to form a net-shaped solidified body, the void part, the foundation pore and the interface of a new-old structure are filled, the stability of the whole reinforcing structure and the cohesiveness between the new-old structure are ensured, so that the new-old structure forms a whole, the bearing capacity and the durability of the reinforcing structure are further greatly improved, and meanwhile, the problem of uneven stress of the conventional reinforcing structure caused by interface stripping is effectively solved.

Furthermore, a plurality of the guide pipes are annularly arranged in a plurality of circles, and each layer of step of the expanded foundation is correspondingly provided with a circle of guide pipe. The multiple circles of annular arrangement enable grouting holes to be uniformly distributed, so that grouting liquid can be uniformly pressed into the reinforcing structure and/or the foundation, full filling of void parts and/or foundation pores is achieved, the problem of filling leakage or incomplete filling is avoided, and the stability of the reinforcing structure is improved.

Furthermore, the distance between adjacent guide pipes in the same circle is less than 1.8m, the denser the guide pipes are, the more the filling of all the void parts or foundation pores by grout can be ensured, but considering the construction requirements of construction machines and the effective range of the grout reinforcement of the guide pipes is about 0.5-1.8 m, the distance between adjacent guide pipes in the same circle should be less than 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 enlarged foundation and located in the foundation is 2-3 m.

Further, the guide pipe penetrating through the enlarged foundation is arranged in parallel to the bridge pier, and the bottom end of the guide pipe which does not penetrate through the enlarged foundation is arranged in an inward inclined mode; preferably, the included angle between the obliquely arranged guide pipe and the pier is 45-60 degrees.

The pipe that the slope set up extends to in the ground of enlarged base bottom, is convenient for fill the void part or the ground hole of enlarged base bottom, has improved pier bottom foundation structure's bearing capacity, more is favorable to improving the steadiness of pier.

Furthermore, the longitudinal section of the water interception wall is trapezoidal; preferably, the gradient of the trapezoid is 1: 0.3. the trapezoidal cut-off wall can intercept rivers more effectively, reduces the impact force of rivers to infrastructure.

The invention also provides a construction method of the pier enlarged foundation reinforcement structure, which comprises the following steps:

arranging a plurality of guide pipes around the 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 conduit at low pressure, wherein the grouting liquid flows into the foundation under the action of pressure, so that the void part and/or the foundation pore space are/is filled;

concrete is poured on the periphery of the enlarged foundation and the pier to form an annular cutoff wall;

processing the enlarged foundation, and pouring concrete on the enlarged foundation between the cut-off wall and the pier or above the enlarged foundation and the foundation to form a concrete reinforcing layer;

and injecting grouting liquid into the conduit at high pressure, wherein the grouting liquid flows into the foundation under the action of pressure, and the filling of the hole between the concrete reinforcing layer and the enlarged foundation is realized.

The reinforcement method of the invention is implemented by injecting grouting liquid twice, wherein the first low-pressure injection is to fill the void part and the foundation pore, so as to realize grouting reinforcement and ensure the stability of the concrete reinforcement layer in the construction process, but after the concrete reinforcement layer is constructed, the interface between the concrete reinforcement layer and the enlarged foundation still has pores, and the pores are filled by the second high-pressure injection, so that the new reinforcement structure and the old reinforcement structure form a whole, thereby improving the stability and the cohesiveness of the whole reinforcement structure and improving the bearing capacity and the durability of the reinforcement structure.

Furthermore, a plurality of the guide pipes are annularly arranged in a plurality of circles, and each layer of step of the expanded foundation is correspondingly provided with a circle of guide pipe.

Further, the guide pipe penetrating through the enlarged foundation is arranged in parallel to the bridge pier, and the bottom end of the guide pipe which does not penetrate through the enlarged foundation is arranged in an inward inclined mode; 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 water-cement ratio of the cement paste is 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 1.5 MPa.

Further, in the high-pressure injection, the injection sequence is as follows: the conduit near the front cut-off wall, the conduit near the side cut-off wall and the conduit near the back cut-off wall;

the water-intercepting walls comprise a front water-intercepting wall, a rear water-intercepting wall and side water-intercepting walls, wherein the front water-intercepting wall is located on the upstream side along the water flow direction, the rear water-intercepting wall is located on the downstream side along the water flow direction, and the side water-intercepting walls are located on the other two sides.

Advantageous effects

Compared with the prior art, the reinforced structure of the pier enlarged foundation 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 enlarged foundation and the foundation around the enlarged foundation, so that the condition that a river erodes the pier foundation is avoided, the number of the void parts of the pier foundation of the bridge is reduced, meanwhile, the area of the original enlarged foundation is increased, and the bearing capacity of a new foundation is higher; the plurality of guide pipes are like a steel bar framework 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, can be injected with grouting liquid through the guide pipes, the grouting liquid is diffused in a void part and/or a foundation pore to form a net-shaped solidified body, the void part, the foundation pore and the interface of a new-old structure are filled, the stability of the whole reinforcing structure and the cohesiveness between the new-old structure are ensured, so that the new-old structure forms a whole, the bearing capacity and the durability of the reinforcing structure are further greatly improved, and meanwhile, the problem of uneven stress of the conventional reinforcing structure caused by interface stripping is effectively solved.

Drawings

In order to more clearly illustrate the technical solution of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only one embodiment of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on the drawings without creative efforts.

Fig. 1 is a front view of a pier enlarged foundation reinforcing structure in embodiment 1 of the present invention;

fig. 2 is a top view of a pier enlarged foundation reinforcing structure in embodiment 1 of the present invention;

fig. 3 is a flowchart of a construction method of a pier enlarged foundation reinforcement structure in embodiment 1 of the present invention;

fig. 4 is a front view of a reinforcing structure for an enlarged foundation of a pier in example 2 of the present invention, and the numerals in fig. 4 each represent a size in cm;

fig. 5 is a plan view of a reinforcing structure for an enlarged foundation of a pier in example 2 of the present invention, and numerals in fig. 5 each indicate a size in cm;

wherein, 1-pier, 2-conduit, 3-cut-off wall, 31-front cut-off wall, 32-rear cut-off wall, 33-side cut-off wall, 4-concrete reinforced layer, 5-enlarged foundation, 6-foundation, 7-ground line, A is the water flow direction.

Detailed Description

The technical solutions in the present invention are clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

As shown in fig. 1 and 2, the pier enlarged foundation reinforcement structure provided by the invention comprises a pier 1 and an enlarged foundation 5 arranged below the pier 1, wherein a concrete reinforcement layer 4 is arranged above the enlarged foundation 5 and a foundation 6 (or the concrete reinforcement layer 4 is arranged above the enlarged foundation 5), and the concrete reinforcement layer 4 is arranged around the periphery of the pier 1; the water-intercepting walls 3 are arranged along the periphery of the concrete reinforcing layer 4, the water-intercepting walls 3 comprise front water-intercepting walls 31, rear water-intercepting walls 32 and side water-intercepting walls 33, the front water-intercepting walls 31 are water-intercepting walls which are arranged along the water flow direction and on the upstream side, the rear water-intercepting walls 32 are water-intercepting walls which are arranged along the water flow direction and on the downstream side, and the side water-intercepting walls 33 are water-intercepting walls on the other two sides; the concrete reinforcing layer 4 is provided with a plurality of guide pipes 2, the plurality of guide pipes 2 penetrate through the concrete reinforcing layer 4 and/or the concrete reinforcing layer 4 and the enlarged foundation 5 and extend into the foundation 6, namely, the first condition is that part of the guide pipes 2 penetrate through the concrete reinforcing layer 4 and then directly extend into the foundation 6, and the other condition is that part of the guide pipes 2 penetrate through the concrete reinforcing layer 4 and the enlarged foundation 5 and then extend into the foundation 6; the second is that all the guide pipes 2 only pass through the concrete reinforcing layer 4 and then directly extend into the foundation 6; thirdly, all the conduits 3 pass through the concrete reinforcing layer 4 and the enlarged foundation 5 and then extend into the foundation 6.

As shown in fig. 2, the plurality of pipes 2 are annularly arranged in a plurality of circles, each step of the enlarged foundation 5 corresponds to one circle of pipe 2 (the enlarged foundation 5 in fig. 2 has two steps, each step corresponds to one circle of pipe 2), the number of circles of pipes 2 is generally 4-6 circles, in this embodiment, 4 circles of pipes 2 are provided, two circles of pipes 2 pass through the concrete reinforcing layer 4 and the enlarged foundation 5, and the other two circles of pipes 2 only pass through the concrete reinforcing layer 4. The multi-ring annular arrangement can enable grouting holes (namely conduits) to be uniformly distributed, so that grouting liquid can be uniformly pressed into the reinforcing structure and/or the foundation 6, full filling of a void part and/or a foundation pore is realized, the problem of filling leakage or incomplete filling is avoided, and the stability of the reinforcing structure is improved.

As shown in fig. 1, the guide tubes 2 passing through the enlarged footing 5 are disposed parallel to the pier 1 (or perpendicular to the enlarged footing 5), and the bottom ends of the guide tubes 2 not passing through the enlarged footing 5 are disposed to be inclined inward (i.e., inclined toward the enlarged footing 5); the included angle between the obliquely arranged guide pipe 2 and the pier 1 is 45-60 degrees. The pipe 2 that the slope set up extends to in the foundation 6 of 5 bottoms of enlarged basis, is convenient for fill the void part or the foundation hole of enlarged basis bottom, has improved pier bottom foundation structure's bearing capacity, more is favorable to improving the steadiness of pier.

In this embodiment, the duct 2 is a steel pipe, the diameter of the duct 2 is 60 to 80mm, preferably 75mm, the length is 5 to 7m, and the length of the part of the duct 2 passing through the enlarged foundation 5 and located in the foundation 6 (i.e., the depth of the duct 2 at the bottom of the enlarged foundation 5) is 2 to 3 m. The denser the conduits 2 are, the more the filling of all the void parts or foundation pores can be ensured, but considering the construction requirements of construction machines and the effective range of slurry reinforcement of the conduits 2 is about 0.5-1.8 m, the distance between adjacent conduits 2 on the same ring should be less than 1.8 m.

As shown in fig. 1, the front cutoff wall 31, the rear cutoff wall 32, and the side cutoff wall 33 form an annular cutoff wall 3, the longitudinal section of the cutoff wall 3 is trapezoidal, and the gradient of the trapezoid is 1: 0.3. the trapezoidal cut-off wall can intercept rivers more effectively, reduces the impact force of rivers to infrastructure. The height of the water interception wall is consistent with that of the enlarged foundation.

As shown in fig. 3, the present invention also provides a construction method of the pier enlarged foundation reinforcement structure, including the steps of:

(1) and (5) preparing.

The enlarged foundation 5 is measured and lofted, cofferdam and drainage construction is carried out, drainage ditches and collector wells are arranged on the inner side of the cofferdam, the reinforcing construction process is prevented from being scoured by river water, and the influence of water seepage is reduced.

(2) Arranging a plurality of guide pipes 2 around the pier 1, wherein the bottom ends of the guide pipes 2 extend into a foundation 6 or extend into the foundation 6 through an enlarged foundation 5, namely, the first condition is that part of the guide pipes 2 directly extend into the foundation 6 after penetrating through a concrete reinforcing layer 4, and part of the guide pipes 2 extend into the foundation 6 after penetrating through the concrete reinforcing layer 4 and the enlarged foundation 5; the second is that all the guide pipes 2 only pass through the concrete reinforcing layer 4 and then directly extend into the foundation 6; thirdly, all the conduits 3 pass through the concrete reinforcing layer 4 and the enlarged foundation 5 and then extend into the foundation 6.

As shown in fig. 1 and 2, the plurality of conduits 2 are arranged in a plurality of circles and a circle of conduits 2 is arranged on each step of the enlarged base 5. The guide pipe 2 penetrating through the enlarged foundation 5 is arranged in parallel to the pier 1, the bottom end of the guide pipe 2 not penetrating through the enlarged foundation 5 is arranged in an inward inclined mode, and an included angle between the inclined guide pipe 2 and the pier 1 is 45-60 degrees. The conduit 2 is a steel pipe, the diameter of the conduit 2 is 60-80 mm, preferably 75mm, and the length is 5-7 m.

(3) And (4) preparing grouting liquid.

The grouting liquid is cement water glass slurry, the cement water glass slurry takes ordinary portland cement and 40 baume degree water glass as main pulping materials, the 40 baume degree water glass is diluted to 35 baume degree, the modulus of the water glass is 2.8, the ordinary portland cement is diluted to prepare cement slurry, the water cement ratio of the cement slurry is 1: 0.5-1: 1, and the cement water glass slurry is prepared from the cement slurry and the water glass in 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 concretion rate under the condition of flowing water and the like of single-liquid cement slurry, improves the effect of cement grouting, enlarges the range of cement grouting and can achieve the aim of quickly stopping leakage.

(4) Aiming at the problem that the foundation 6 at the bottom of the enlarged foundation 5 is loose, cement water glass slurry is injected into the guide pipe 2 through the grouting pipe at low pressure, the cement water glass slurry in the guide pipe 2 flows into the foundation 6 under the action of 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 slurry bubble body can be obviously reinforced within a range of 0.5-1.8 m, and the filling of a void part and/or a foundation pore is realized.

In this embodiment, the pressure during low-pressure injection is 0.3 to 0.5MPa, and when a grouting liquid emerges from the top of the guide pipe 2, the injection is stopped. According to the hard degree of 6 soil layers of the foundation, grouting can be performed in the modes of filling, permeating, compacting, splitting and the like, and grouting reinforcement is performed on the pier in the range of 2-3 m of 1 foundation. The slip casting pipe is the hose, can insert and extract pipe 2, also can move in pipe 2, and when the slip casting (i.e. pour into cement glass thick liquid), the slip casting pipe is 30~50cm apart from pipe 2 bottom.

(5) The grouting liquid in the conduit 2 is removed for the next grouting.

(6) And concrete is poured on the periphery of the enlarged foundation 5 and the pier 1 to form an annular water-stop wall.

As shown in fig. 2, the cut-off wall 3 includes a front cut-off wall 31, a rear cut-off wall 32 and side cut-off walls 33, the front cut-off wall 31 is located on the upstream side in the water flow direction, the rear cut-off wall 32 is located on the downstream side in the water flow direction, and the side cut-off walls 33 are located on the other two sides.

(7) The enlarged foundation 5 is roughened and brushed, and concrete is poured over the enlarged foundation 5 and the foundation 6 between the cut-off wall and the pier 1 to form the 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 strength requirement of design, and the height of the concrete reinforcing layer 4 is 1-2 m generally. When the concrete reinforcing layer 4 is poured, the top end of the guide pipe 2 is ensured to be higher than the concrete reinforcing layer 4, so that the guide pipe 2 is prevented from being blocked by concrete, and subsequent grouting liquid is not favorably injected.

(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 conduit 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 1.5 MPa. The grouting liquid is injected firstly from the high water head to the low water head, and the grouting liquid is injected firstly from the high water head end to ensure that the grouting is full under the action of water flow. Therefore, in this embodiment, the injection sequence is: the pipes 2 near the front cut-off wall 31, the pipes 2 near the side cut-off walls 33, and the pipes 2 near the rear cut-off wall 32 are simultaneously injected (for example, when the pipes 2 near the front cut-off wall 31 are injected, the pipes 2 near the front cut-off wall 31 are simultaneously injected).

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 focused mode, and the grouting amount can be adjusted in time according to the conditions of field slurry suction amount, grouting pressure, surface slurry emitting distance and the like. For example, when the pump pressure is high and the slurry suction amount is small at the beginning of grouting, or the situation suddenly occurs in the grouting process, the slurry feeding is stopped, and the grouting is performed after the conduit 2 is cleaned. The grouting is ended when one of the following conditions occurs: a. continuing grouting for 10min when the injection rate is less than 1L/min; b. when the grout discharging point is out of the grouting range of 3-5 m; c. the grouting amount of the single guide pipe 2 is 1.5-2.0 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 pore is not compact, and performing the step (10) if the structure pore is compact.

(10) And cutting off the guide pipes 2 above the surface of the concrete reinforcing layer 4, reserving the guide pipes 2 below the surface, and under the bonding action of the grouting liquid, jointly stressing the new-old foundation (namely the concrete reinforcing layer 4 and the enlarged foundation 5) and the foundation 6 to form a reinforcing structure of the pier enlarged foundation.

The construction method adopts secondary grouting, the first low-pressure grouting ensures the stability of the foundation soil layer, so that the subsequent concrete reinforcing layer 4 is stable in the pouring process, and the second high-pressure grouting ensures that the concrete reinforcing layer 4, the enlarged foundation 5, the foundation soil layer and the reserved pipe 2 are mutually bonded to form a whole reinforcing structure, so that a structural 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

The bay pond power station bridge is located in Longshan county of Hunan West Xiang of Hunan province, the superstructure is a reinforced concrete hyperbolic arch bridge of 4 × 39m +1 × 25m, and the pier foundation is an expanded foundation. Through the special inspection of the bridge by an engineering detection unit, the wall masonry mortar of the bridge pier falls off, and a local cavity and a foundation are washed and drawn. The pier enlarged foundation reinforcing structure and the construction method thereof are adopted to carry out reinforcing treatment, the newly-built concrete structure (namely the concrete reinforcing layer and the cut-off wall) adopts C30 material, the grouting liquid is cement water glass grouting liquid, and the reinforcing structure chart is shown in fig. 4 and 5.

And the bridge reinforcing structure is subjected to quality detection and monitoring measurement from 5 days in 7 months in 2019 to 30 days in 9 months in 2019. The quality of the reinforced structure of the enlarged foundation of all piers is detected by adopting an 800M geological radar instrument, and the detection result shows that the loose foundation, the pore space and the new-old structure interface are not provided with non-compact signals, so that the reinforced structure has better integrity. In the foundation reinforcement construction and the upper structure main arch bridge and bridge deck pavement construction process, the settlement height difference of the pier foundation plane is less than 0.2mm, and the accumulated settlement is less than 1mm, which shows that the stress of the enlarged foundation reinforcement structure is uniform during the full-bridge reinforcement construction period and has higher bearing capacity.

The above disclosure is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of changes or modifications within the technical scope of the present invention, and shall be covered by the scope of the present invention.

Claims (10)

1. The utility model provides a pier enlarges basis reinforced structure, includes the pier and locates the enlarged foundation of pier below, its characterized in that: a concrete reinforcing layer is arranged above the enlarged foundation or the enlarged foundation and the foundation, and the concrete reinforcing layer is arranged around the periphery of the 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.

2. The pier enlarging foundation reinforcing structure of claim 1, wherein: the plurality of the guide pipes are annularly arranged in a plurality of circles, and each layer of step of the enlarged foundation is provided with a circle of guide pipe correspondingly.

3. The pier enlarging foundation reinforcing structure of claim 2, wherein: the distance between the adjacent conduits in the same circle is less than 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 enlarged foundation and located in the foundation is 2-3 m.

4. The pier enlarging foundation reinforcing structure of claim 1, wherein: the guide pipe penetrating through the enlarged foundation is arranged in parallel to the bridge pier, and the bottom end of the guide pipe which does not penetrate through the enlarged foundation is arranged in an inward inclined mode;

preferably, the included angle between the obliquely arranged guide pipe and the pier is 45-60 degrees.

5. The pier enlarged foundation reinforcing structure of any one of claims 1 to 4, wherein: the longitudinal section of the water interception wall is trapezoidal;

preferably, the gradient of the trapezoid is 1: 0.3.

6. a construction method of an enlarged foundation reinforcement structure for a pier according to any one of claims 1 to 5, comprising:

arranging a plurality of guide pipes around the 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 conduit at low pressure, wherein the grouting liquid flows into the foundation under the action of pressure, so that the void part and/or the foundation pore space are/is filled;

concrete is poured on the periphery of the enlarged foundation and the pier to form an annular cutoff wall;

processing the enlarged foundation, and pouring concrete on the enlarged foundation between the cut-off wall and the pier or above the enlarged foundation and the foundation to form a concrete reinforcing layer;

and injecting grouting liquid into the conduit at high pressure, wherein the grouting liquid flows into the foundation under the action of pressure, and the filling of the hole between the concrete reinforcing layer and the enlarged foundation is realized.

7. The construction method according to claim 6, wherein: the plurality of guide pipes are annularly arranged in a plurality of circles, and each layer of step of the expanded foundation is correspondingly provided with a circle of guide pipe;

preferably, the conduit which passes through the enlarged foundation is arranged in parallel with the bridge pier, and the bottom end of the conduit which does not pass through the enlarged foundation is arranged in an inward inclined manner; preferably, the included angle between the obliquely arranged guide pipe and the pier is 45-60 degrees.

8. The construction method according to claim 6, wherein: the grouting liquid is cement water glass slurry which is prepared from cement slurry and water glass in a volume ratio of 1: 0.05-1: 0.1; the water-cement ratio of the cement paste is 1: 0.5-1: 1, the modulus of the water glass is 2.8, and the water glass is 35 Baume degree water glass.

9. The construction method according to claim 6, wherein: the pressure during low-pressure injection is 0.3-0.5 MPa, and the pressure during high-pressure injection is 1.5 MPa.

10. The construction method according to any one of claims 6 to 9, wherein: in the high-pressure injection, the injection sequence is as follows: the conduit near the front cut-off wall, the conduit near the side cut-off wall and the conduit near the back cut-off wall;

the water-intercepting walls comprise a front water-intercepting wall, a rear water-intercepting wall and side water-intercepting walls, wherein the front water-intercepting wall is located on the upstream side along the water flow direction, the rear water-intercepting wall is located on the downstream side along the water flow direction, and the side water-intercepting walls are located on the other two sides.

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