阅读说明：本技术 一种采用钢纤维自应力混凝土加固石拱桥的方法 (Method for reinforcing stone arch bridge by adopting steel fiber self-stress concrete ) 是由 许强 刘巍 范明坤 黎涛辉 程应杰 张寒韬 奚映钟 于 2021-08-24 设计创作，主要内容包括：本发明提供一种采用钢纤维自应力混凝土加固石拱桥的方法,包括：安装支撑加固单元；安装模板；制备钢纤维自应力混凝土；将钢纤维自应力混凝土浇入模板中,并振捣；在喷水养护结束后,均匀安装多个预应力锚索。本发明提供的一种采用钢纤维自应力混凝土加固石拱桥的方法具有以下优点：本发明采用钢纤维自应力混凝土因其硬化过程中产生膨胀并产生2～10MPa自压应力,使得内衬拱混凝土内部密实、均匀、无空洞,与原石拱圈结合紧密,从而使得新老结构共同受力,加固效果好。(The invention provides a method for reinforcing a stone arch bridge by using steel fiber self-stress concrete, which comprises the following steps: installing a supporting and reinforcing unit; installing a template; preparing steel fiber self-stress concrete; pouring the steel fiber self-stress concrete into a template and vibrating; and after the water spraying maintenance is finished, uniformly installing a plurality of prestressed anchor cables. The method for reinforcing the stone arch bridge by adopting the steel fiber self-stress concrete has the following advantages: according to the invention, the steel fiber self-stress concrete is adopted to expand in the hardening process and generate 2-10 MPa self-pressure stress, so that the lining arch concrete is compact, uniform and free of cavities and is tightly combined with the original stone arch ring, so that the new and old structures are stressed together, and the reinforcing effect is good.)

1. A method for reinforcing a stone arch bridge by using steel fiber self-stress concrete is characterized by comprising the following steps:

step 1, mounting a supporting and reinforcing unit below an original stone arch ring (1); the supporting and reinforcing unit comprises a first layer of longitudinal steel bars (4.1), a second layer of longitudinal steel bars (4.2), transverse steel bars (5) and embedded steel bars (6);

step 2, installing a template;

fixedly mounting the template (7) below the second layer of longitudinal steel bars (4.2);

step 3, preparing the steel fiber self-stress concrete:

step 3.1, determining the mixture ratio of the materials as follows:

step 3.2, dry stirring and mixing:

dry-stirring the steel fiber, the sand and the crushed stone according to the formula ratio to uniformly mix the steel fiber, the sand and the crushed stone to obtain a uniformly mixed material;

step 3.3, wet stirring and mixing:

adding the cement and water with the formula amount into the uniformly mixed material obtained in the step 3.2, and carrying out wet stirring and mixing for 10-20 min to obtain the steel fiber self-stress concrete;

step 4, pouring the steel fiber self-stress concrete obtained in the step 3 into a template (7), and obliquely inserting an inserted vibrator into the steel fiber self-stress concrete in the template (7) for vibrating;

in the step, the steel fiber self-stress concrete poured into the template (7) is gradually hardened; in the hardening process, the steel fiber self-stress concrete expands, and a certain pre-stress is generated inside the concrete under the restriction of the binding force of the steel bars and the steel fibers inside the concrete and the constraint action of an external interface, so that the cast-in-place lining arch concrete is compact, uniform and free of cavities inside and is tightly combined with the original stone arch ring (1), and a new structure and an old structure are stressed together;

step 5, after the steel fiber self-stress concrete is initially set, covering plastic cloth on the outer part of the template (7) for moisturizing, spraying water once every fixed time, after the steel fiber self-stress concrete is completely hardened, removing the template (7), spraying water for curing for fixed time, and forming a steel fiber self-stress concrete lining arch (2) by the steel fiber self-stress concrete;

after the water spraying maintenance is finished, uniformly installing a plurality of prestressed anchor cables (3); the installation mode of the prestressed anchor cable (3) is as follows: one end of the prestressed anchor cable (3) is positioned at the bottom of the steel fiber self-stress concrete lining arch (2), and the other end of the prestressed anchor cable penetrates through the steel fiber self-stress concrete lining arch (2) and the original stone arch ring (1) in sequence and is embedded into the structure of the stone arch bridge.

2. The method for reinforcing the stone arch bridge by using the steel fiber self-stress concrete according to the claim 1, wherein in the step 1, the concrete installation method of the supporting and reinforcing unit is as follows:

step 1.1, paving a plurality of first layer longitudinal steel bars (4.1) which are arranged in parallel and a plurality of transverse steel bars (5) which are arranged in parallel on the lower surface of the original stone arch ring (1); the crossed positions of the first layer of longitudinal steel bars (4.1) and the transverse steel bars (5) are bound and fixed;

step 1.2, arranging a plurality of second layers of parallel longitudinal steel bars (4.2) below the first layer of longitudinal steel bars (4.1) at a distance d, wherein each second layer of longitudinal steel bars (4.2) is positioned right below the corresponding first layer of longitudinal steel bars (4.1);

step 1.3, arranging one embedded bar (6) at the intersection position of each first layer of longitudinal steel bar (4.1) and each transverse steel bar (5), wherein the bottom of the embedded bar (6) is fixedly bound with the corresponding second layer of longitudinal steel bar (4.2), the middle of the embedded bar (6) is fixedly bound with the first layer of longitudinal steel bar (4.1) and each transverse steel bar (5), and the top of the embedded bar (6) is drilled into the original stone arch ring (1);

the distance d between the first layer of longitudinal steel bars (4.1) and the second layer of longitudinal steel bars (4.2) is limited by the embedded steel bars (6) and is the thickness of the cast-in-place concrete layer (6).

3. The method for reinforcing the stone arch bridge by using the steel fiber self-stress concrete according to claim 1, wherein the pre-stress generated in the concrete in the step 4 is 2-10 Mpa.

4. A method for reinforcing a stone arch bridge by using steel fiber self-stressed concrete according to claim 1, characterized in that the thickness ratio of the steel fiber self-stressed concrete lining arch (2) to the original stone arch ring (1) is: 0.6 to 1.

Technical Field

The invention belongs to the technical field of bridge engineering reinforcement and maintenance, and particularly relates to a method for reinforcing a stone arch bridge by using steel fiber self-stress concrete.

Background

A stone arch bridge is one of the most widely used forms of bridge construction. The stone arch bridge has the following advantages: (1) the arch structure is adopted, so that the spanning capability is high; (2) the material can be fully obtained from local resources, and compared with a beam bridge, a large amount of steel and cement can be saved; (3) the durability is good, and the maintenance and repair cost is less compared with that of a beam bridge; (4) the appearance is beautiful; (5) the structure is simple, the construction technology is easy to master, and the method is favorable for wide application.

In recent years, with the development of economy and high speed, the traffic transportation industry mainly based on highways is rapidly developed, the traffic flow is large, the vehicle load is rapidly increased, and the design load grade of the original stone arch bridge does not meet the passing requirement of the existing vehicles. Therefore, how to improve the bearing capacity of the stone arch bridge and reinforce the stone arch bridge is a matter which needs to be solved urgently at present.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides a method for reinforcing a stone arch bridge by adopting steel fiber self-stress concrete, which can effectively solve the problems.

The technical scheme adopted by the invention is as follows:

the invention provides a method for reinforcing a stone arch bridge by using steel fiber self-stress concrete, which comprises the following steps:

step 1, mounting a supporting and reinforcing unit below an original stone arch ring (1); the supporting and reinforcing unit comprises a first layer of longitudinal steel bars (4.1), a second layer of longitudinal steel bars (4.2), transverse steel bars (5) and embedded steel bars (6);

step 2, installing a template;

fixedly mounting the template (7) below the second layer of longitudinal steel bars (4.2);

step 3, preparing the steel fiber self-stress concrete:

step 3.1, determining the mixture ratio of the materials as follows:

step 3.2, dry stirring and mixing:

dry-stirring the steel fiber, the sand and the crushed stone according to the formula ratio to uniformly mix the steel fiber, the sand and the crushed stone to obtain a uniformly mixed material;

step 3.3, wet stirring and mixing:

adding the cement and water with the formula amount into the uniformly mixed material obtained in the step 3.2, and carrying out wet stirring and mixing for 10-20 min to obtain the steel fiber self-stress concrete;

step 4, pouring the steel fiber self-stress concrete obtained in the step 3 into a template (7), and obliquely inserting an inserted vibrator into the steel fiber self-stress concrete in the template (7) for vibrating;

in the step, the steel fiber self-stress concrete poured into the template (7) is gradually hardened; in the hardening process, the steel fiber self-stress concrete expands, and a certain pre-stress is generated inside the concrete under the restriction of the binding force of the steel bars and the steel fibers inside the concrete and the constraint action of an external interface, so that the cast-in-place lining arch concrete is compact, uniform and free of cavities inside and is tightly combined with the original stone arch ring (1), and a new structure and an old structure are stressed together;

step 5, after the steel fiber self-stress concrete is initially set, covering plastic cloth on the outer part of the template (7) for moisturizing, spraying water once every fixed time, after the steel fiber self-stress concrete is completely hardened, removing the template (7), spraying water for curing for fixed time, and forming a steel fiber self-stress concrete lining arch (2) by the steel fiber self-stress concrete;

after the water spraying maintenance is finished, uniformly installing a plurality of prestressed anchor cables (3); the installation mode of the prestressed anchor cable (3) is as follows: one end of the prestressed anchor cable (3) is positioned at the bottom of the steel fiber self-stress concrete lining arch (2), and the other end of the prestressed anchor cable penetrates through the steel fiber self-stress concrete lining arch (2) and the original stone arch ring (1) in sequence and is embedded into the structure of the stone arch bridge.

Preferably, in step 1, the specific installation method of the supporting and reinforcing unit is as follows:

step 1.1, paving a plurality of first layer longitudinal steel bars (4.1) which are arranged in parallel and a plurality of transverse steel bars (5) which are arranged in parallel on the lower surface of the original stone arch ring (1); the crossed positions of the first layer of longitudinal steel bars (4.1) and the transverse steel bars (5) are bound and fixed;

step 1.2, arranging a plurality of second layers of parallel longitudinal steel bars (4.2) below the first layer of longitudinal steel bars (4.1) at a distance d, wherein each second layer of longitudinal steel bars (4.2) is positioned right below the corresponding first layer of longitudinal steel bars (4.1);

step 1.3, arranging one embedded bar (6) at the intersection position of each first layer of longitudinal steel bar (4.1) and each transverse steel bar (5), wherein the bottom of the embedded bar (6) is fixedly bound with the corresponding second layer of longitudinal steel bar (4.2), the middle of the embedded bar (6) is fixedly bound with the first layer of longitudinal steel bar (4.1) and each transverse steel bar (5), and the top of the embedded bar (6) is drilled into the original stone arch ring (1);

the distance d between the first layer of longitudinal steel bars (4.1) and the second layer of longitudinal steel bars (4.2) is limited by the embedded steel bars (6) and is the thickness of the cast-in-place concrete layer (6).

Preferably, in the step 4, the pre-stress generated in the concrete is 2-10 Mpa.

Preferably, the thickness ratio of the steel fiber self-stress concrete lining arch (2) to the original stone arch ring (1) is as follows: 0.6 to 1.

The method for reinforcing the stone arch bridge by adopting the steel fiber self-stress concrete has the following advantages:

according to the invention, the steel fiber self-stress concrete is adopted to expand in the hardening process and generate 2-10 MPa self-pressure stress, so that the lining arch concrete is compact, uniform and free of cavities and is tightly combined with the original stone arch ring, so that the new and old structures are stressed together, and the reinforcing effect is good.

Drawings

FIG. 1 is a schematic external structural view of a method for reinforcing a stone arch bridge by using steel fiber self-stressed concrete according to the present invention;

fig. 2 is a schematic internal structure diagram of a method for reinforcing a stone arch bridge by using steel fiber self-stress concrete provided by the invention.

Detailed Description

In order to make the technical problems, technical solutions and advantageous effects solved by the present invention more clearly apparent, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The invention provides a method for reinforcing a stone arch bridge by using steel fiber self-stress concrete, which adopts a steel fiber self-stress concrete to reinforce the stone arch bridge, has the advantages of clear design concept, good reinforcing effect and good economic benefit, can ensure that the interior of the concrete of the inner lining arch is compact, uniform and free of cavities, is tightly combined with an original stone arch ring, and ensures that new and old structures bear force together.

Referring to fig. 1 and 2, the present invention provides a method for reinforcing a stone arch bridge using steel fiber self-stressed concrete, comprising the steps of:

step 1, mounting a supporting and reinforcing unit below an original stone arch ring 1; the supporting and reinforcing unit comprises a first layer of longitudinal steel bars 4.1, a second layer of longitudinal steel bars 4.2, transverse steel bars 5 and embedded steel bars 6;

the specific installation method of the supporting and reinforcing unit comprises the following steps:

step 1.1, paving a plurality of first layers of longitudinal steel bars 4.1 arranged in parallel and a plurality of transverse steel bars 5 arranged in parallel on the lower surface of an original stone arch ring 1; binding and fixing the crossed positions of the longitudinal steel bars 4.1 and the transverse steel bars 5 of the first layer;

step 1.2, a plurality of second layers of parallel longitudinal steel bars 4.2 are arranged below the first layer of longitudinal steel bars 4.1 at a distance d, and each second layer of longitudinal steel bar 4.2 is positioned right below the corresponding first layer of longitudinal steel bar 4.1;

step 1.3, arranging a planting bar 6 at the intersection position of each first layer of longitudinal steel bar 4.1 and each transverse steel bar 5, binding and fixing the bottom of the planting bar 6 with the corresponding second layer of longitudinal steel bar 4.2, binding and fixing the middle part of the planting bar 6 with the first layer of longitudinal steel bar 4.1 and the transverse steel bar 5, and drilling the top of the planting bar 6 into the original stone arch ring 1; specifically, holes are drilled in the corresponding positions of the original stone arch ring 1 in advance, and then the tops of the planting bars 6 are drilled into the corresponding holes.

Through planting the muscle 6, limited first layer longitudinal reinforcement 4.1 and the distance d of second layer longitudinal reinforcement 4.2, be the thickness of cast-in-place concrete layer 6.

Step 2, installing a template;

a template 7 is fixedly installed below the second layer of longitudinal steel bars 4.2;

step 3, preparing the steel fiber self-stress concrete:

step 3.1, determining the mixture ratio of the materials as follows:

the material requirements are as follows:

(1) the cement is 4.0-grade self-stress sulphoaluminate cement. The compressive strength is not less than 32.5MPa in 7 days and not less than 42.5MPa in 28 days;

(2) the sand is high-quality river sand, and the fineness modulus is more than 2.3 and less than 3.0;

(3) the crushed stone is limestone crushed stone with the particle size of 5-20 mm;

(4) the water is selected to meet the drinking water standard;

(5) the steel fiber is selected to have the diameter of 0.75mm, the length of 60mm, the tensile strength of not less than 1300MPa, the shape of which is a straight shape with hooks at two ends.

Step 3.2, dry stirring and mixing:

dry-stirring the steel fiber, the sand and the crushed stone according to the formula ratio to uniformly mix the steel fiber, the sand and the crushed stone to obtain a uniformly mixed material;

step 3.3, wet stirring and mixing:

adding the cement and water with the formula amount into the uniformly mixed material obtained in the step 3.2, and carrying out wet stirring and mixing for 10-20 min to obtain the steel fiber self-stress concrete;

therefore, in the invention, in order to ensure that the steel fibers are uniformly distributed in the concrete and prevent the steel fibers from forming lumps, a stirring process of drying firstly and then wetting is adopted. Namely: the steel fiber, the sand and the broken stone are firstly stirred in a dry mode, the steel fiber is scattered, then the cement and the water are added for wet stirring, and the stirring time is properly prolonged and is generally not shorter than 10 min.

Step 4, pouring the steel fiber self-stress concrete obtained in the step 3 into a template 7, and obliquely inserting an inserted vibrator into the steel fiber self-stress concrete in the template 7 for vibrating;

in practical application, the density of the steel fiber self-stress concrete is high, and the friction between the steel fiber self-stress concrete and a conveying pipeline is high during pumping, so that the power of a pump is 20% higher than that of common concrete, and the steel fiber self-stress concrete is poured into the template 7 in the mode.

For the vibrating process: with the insertion type vibrator, the vibrator cannot be vertically inserted into the steel fiber self-stressed concrete because it reduces the bonding effect of the steel fiber and the concrete. The vibrator is required to be obliquely inserted and has an included angle with the horizontal plane of not more than 30 degrees, and a flat plate vibrator can also be adopted. Because the density of the steel fiber material is high, the concrete vibrating time is not suitable to be overlong and generally does not exceed 30s, otherwise, the concrete is easy to layer.

In this step, the steel fiber self-stressed concrete poured into the formwork 7 is gradually hardened; in the hardening process, the steel fiber self-stress concrete expands, and a certain pre-stress, specifically 2-10 Mpa, is generated inside the concrete under the restriction of the binding force of steel bars and steel fibers inside the concrete and the constraint action of an external interface, so that the cast-in-place lining arch concrete is compact, uniform and free of cavities inside and is tightly combined with the original stone arch ring 1, and a new structure and an old structure are stressed together;

step 5, after the steel fiber self-stress concrete is initially set, covering plastic cloth on the outer part of the template 7 for moisturizing, spraying water once every fixed time, after the steel fiber self-stress concrete is completely hardened, removing the template 7, and spraying water for curing for fixed time, wherein the steel fiber self-stress concrete forms a steel fiber self-stress concrete lining arch 2;

for example, after the steel fiber self-stress concrete is initially set (i.e. free water in the concrete is completely dispersed, generally 2-3 hours), covering a plastic cloth for moisturizing, spraying water once every 6 hours, after the concrete is completely hardened (preferably, the compressive strength of the concrete reaches 80% of a designed value, generally 7-14 days), removing a mold, and then spraying water for curing for 28 days.

After the water spraying maintenance is finished, uniformly installing a plurality of prestressed anchor cables 3; and a tension prestressed anchor cable is adopted to further enhance the connection between the lining arch and the original stone arch ring 1. The prestressed anchor cable is a phi 15.2 high-strength steel strand with the tensile strength of 1860 MPa.

The installation mode of the prestressed anchor cable 3 is as follows: one end of the prestressed anchor cable 3 is positioned at the bottom of the steel fiber self-stress concrete lining arch 2, and the other end of the prestressed anchor cable penetrates through the steel fiber self-stress concrete lining arch 2 and the original stone arch ring 1 in sequence and is embedded into the structure of the stone arch bridge.

In general, the thickness ratio of the steel fiber self-stress concrete lining arch 2 to the original stone arch ring 1 is as follows: 0.6 to 1.

The invention provides a method for reinforcing a stone arch bridge by using steel fiber self-stress concrete, which is mainly characterized by comprising the following steps of:

use steel fibre self-stress concrete to replace ordinary cement, the inflation that steel fibre self-stress concrete produced in the hardening process is under the restriction such as reinforcing bar of pouring in concrete inside in advance or steel fibre's adhesion and external interface constraint effect, concrete inside will produce certain pre-stress, this kind of pre-stress that produces under the inside chemical action of concrete becomes chemical pre-stress, use the material that meets the requirements, can produce 2 ~ 10MPa self-stress, thereby make inside the inside compactness of inside lining arch concrete, even, no cavity, combine closely with former stone arch ring, thereby make the common atress of new and old structure.

If the conventional concrete pouring lining arch is adopted, the concrete is often provided with holes and is not compactly poured, and the concrete and the original stone arch ring are often combined untight and even have layering phenomena, so that the new and old arch rings can not be effectively connected with each other according to the design requirements, the new and old structures can not be stressed together, and the reinforcing effect can not meet the current load grade requirement.

The invention provides a method for reinforcing a stone arch bridge by adopting steel fiber self-stress concrete, which is completely different from the traditional mode, is a newly designed reinforcing method for a lining arch of the stone arch bridge and can be used for: the existing stone arch bridge is reinforced by an inner lining arch. Has the following advantages:

1. the design concept is clear, and the effect is clear;

2. the steel fiber self-stress concrete expands and generates 2-10 MPa self-pressure stress in the hardening process, so that the lining arch concrete is compact, uniform and free of cavities and is tightly combined with the original stone arch ring, the new and old structures are stressed together, and the reinforcing effect is good;

3. the steel fiber self-stress concrete has good toughness, impact resistance and fatigue resistance. The thickness of the lining arch can be reduced, and the economic benefit is good;

4. compared with the traditional common reinforced concrete lining arch, the steel fiber self-stress concrete does not need secondary treatment in the later period, and can open traffic as soon as possible; therefore, the technical method has strong practical and practical significance.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and improvements can be made without departing from the principle of the present invention, and such modifications and improvements should also be considered within the scope of the present invention.