A Construction Technology of Demolishing Prestressed Continuous Box Girder Bridge by Hydraulic Blasting

Abstract

The invention discloses a construction technology of demolition of a prestressed continuous box girder bridge through hydraulic blasting. The technical scheme adopted by the construction technology mainly comprises the following steps of (1) performing theoretical analysis; (2) performing demolition of auxiliary structures; (3) performing drilling of holes in a top plate; (4) placing a blasting charge; (5)performing water injection into the box girder; (6) protecting the box girder; (7) performing surrounding layout; and (8) performing blasting, and performing clearing and transportation. After the blasting charge is mounted in the step (4), an adhesive layer is sprayed onto the outer surface of the blasting charge; after the water is injected into the box, the adhesive layer recovers theadhesive property when being in contact with the water, so that further enhancement of the stability of the blasting charge on the inner wall of the box is facilitated; a steel wire is used for preliminary fixation of the blasting charge; the adhesive layer is used for performing secondary fixation on the blasting charge; and when the blasting charge is subjected to strong hydraulic impact, the blasting charge cannot be easily blown away from the preset position, so that the blasting charge can explode at the preset position and realization of complete blasting of the bridge can be facilitated.

Description

technical field

[0001] The invention relates to bridge demolition, in particular to a construction technique for demolishing a prestressed continuous box girder bridge by hydraulic blasting. Background technique

[0002] With the rapid development of our country's economy, the traffic flow of roads has increased rapidly, and the requirements for the use and bearing capacity of existing road and bridge structures are also getting higher and higher. Many bridge structures have been overwhelmed by heavy traffic, and some have exceeded the design. Some bridges have become dangerous due to various reasons, and they are all facing the situation of reinforcement, reconstruction, demolition and reconstruction. For the demolition of bridges in the past, mechanical demolition or drilling and blasting of columns and other parts are often used to perform secondary crushing. This demolition method is difficult to dismantle, causes serious dust pollution, and consumes a lot of manpower an...

Examples

Embodiment

[0044] The concrete preparation method of acrylic acid emulsion film former is as follows:

[0045] (1) Pre-emulsification: Add 50 parts of water, 3 parts of emulsifier, and 10 parts of acrylamide into the reaction bottle, add 6 parts of styrene, 8 parts of butyl acrylate, and 6 parts of acrylic acid under stirring conditions to prepare non-layered White pre-emulsion; (2) Polymerization: add 70 parts of water, 1 part of initiator, 20 parts of pre-emulsion and 10 parts of ammonium persulfate aqueous solution to the reaction bottle, heat up to 65 ° C, keep warm for 1 hour, and neutralize with ammonia water to PH=7.5-8 can be.

[0046] The preparation method of the adhesive layer is as follows: put 10-20 parts of cement mortar, 20-30 parts of acrylic emulsion film-forming material, and 30-40 parts of carboxymethyl starch ether into the reaction bottle, stir for 1 hour, and adjust the reaction temperature to 40-45 ℃; continue to add 3-6 parts of hydroxyethyl cellulose, 1-2 parts ...

example

[0056] Project example: The explosives for hydraulic blasting of the Xuhe Bridge are set in the middle and lower part of the box. If the water depth is about 0.89-1.9m, the depth of the charge is set at 0.5-1.0m. For the middle part of the mid-span, 6 charges are set on one side, and Q=545g is calculated, converted into emulsion explosives, Q is 0.6kg. The setting of the medicine bag is controlled by the height from the top plate. First, measure the total depth of the water outlet and subtract the height from the center of the medicine bag to the bottom plate. A certain number of 40*40cm manholes are opened on the top plate to facilitate the sealing operation in the box.

technical field

[0001] The invention relates to bridge demolition, in particular to a construction technique for demolishing a prestressed continuous box girder bridge by hydraulic blasting. Background technique

[0002] With the rapid development of our country's economy, the traffic flow of roads has increased rapidly, and the requirements for the use and bearing capacity of existing road and bridge structures are also getting higher and higher. Many bridge structures have been overwhelmed by heavy traffic, and some have exceeded the design. Some bridges have become dangerous due to various reasons, and they are all facing the situation of reinforcement, reconstruction, demolition and reconstruction. For the demolition of bridges in the past, mechanical demolition or drilling and blasting of columns and other parts are often used to perform secondary crushing. This demolition method is difficult to dismantle, causes serious dust pollution, and consumes a lot of manpower an...

Examples

Embodiment

[0044] The concrete preparation method of acrylic acid emulsion film former is as follows:

[0045] (1) Pre-emulsification: Add 50 parts of water, 3 parts of emulsifier, and 10 parts of acrylamide into the reaction bottle, add 6 parts of styrene, 8 parts of butyl acrylate, and 6 parts of acrylic acid under stirring conditions to prepare non-layered White pre-emulsion; (2) Polymerization: add 70 parts of water, 1 part of initiator, 20 parts of pre-emulsion and 10 parts of ammonium persulfate aqueous solution to the reaction bottle, heat up to 65 ° C, keep warm for 1 hour, and neutralize with ammonia water to PH=7.5-8 can be.

[0046] The preparation method of the adhesive layer is as follows: put 10-20 parts of cement mortar, 20-30 parts of acrylic emulsion film-forming material, and 30-40 parts of carboxymethyl starch ether into the reaction bottle, stir for 1 hour, and adjust the reaction temperature to 40-45 ℃; continue to add 3-6 parts of hydroxyethyl cellulose, 1-2 parts ...

example

[0056] Project example: The explosives for hydraulic blasting of the Xuhe Bridge are set in the middle and lower part of the box. If the water depth is about 0.89-1.9m, the depth of the charge is set at 0.5-1.0m. For the middle part of the mid-span, 6 charges are set on one side, and Q=545g is calculated, converted into emulsion explosives, Q is 0.6kg. The setting of the medicine bag is controlled by the height from the top plate. First, measure the total depth of the water outlet and subtract the height from the center of the medicine bag to the bottom plate. A certain number of 40*40cm manholes are opened on the top plate to facilitate the sealing operation in the box.