How to prevent the bridge substructure from freezing.

For bridges located in cold areas, due to the lack of buried depth of piers, abutments, piles and regulating structures, when frost heave, thaw settlement, frozen foundation and wing wall crack occur, the radical solution is to bury the foundation to a certain depth below the freezing line through reconstruction. Prevention and treatment of melting and sinking. Protective covering method is mainly used to prevent thawing settlement, that is, try not to destroy the surface covering around the foundation, especially the turf and peat layer, in order to reduce heat loss. For bridges that have melted slightly, heat insulation and anti-freezing measures should be taken before melting, and materials or soil with good heat insulation should be used for filling and covering to ensure that the foundation soil is in a frozen state. The main measures to prevent frost heaving are as follows: soil replacement on the foundation side: the frost heaving soil on the foundation side is excavated and filled with pure coarse-grained soil without frost heaving, and the thickness of soil replacement should be not less than 2.0 m or twice the pile diameter. If the replacement soil is an impermeable clay layer, the frost heaving effect will be reduced, because unfrozen water will be squeezed out and cannot enter during freezing. At this time, the depth of soil replacement can be deepened or blind ditch can be used to strengthen drainage. Improve the smoothness of the foundation side: change the original rough foundation side into a smooth surface side, coat the foundation wall with industrial vaseline asphalt residue or residue surfactant (the activator can be chromium salt and hydrophobic fatty amine), or lay linoleum on the side to reduce the freezing force. Separate casing method: used for anti-freezing of pile foundation. The shell can be made of steel or reinforced concrete. In order to prevent the casing from being continuously pulled out due to soil frost heave, a steel flange can be set at the bottom of the casing. A mixture of sand and gravel and residual oil (or wax) is filled between the casing and the pile. The main measures to prevent horizontal frost damage of abutment are: strengthening the frost heaving resistance of abutment. Anchor rods and anchor plates can be used to balance the horizontal frost heaving force, or the splayed wall and the front wall can be connected into a whole to increase the reinforcement of the abutment body. Reduce horizontal frost heaving force. Replacement, drainage and heat preservation measures can be adopted. If the abutment back is filled with pure gravel that does not frost heave, a drainage blind ditch shall be set on the abutment back, and thermal insulation materials shall be laid on the abutment back and the lower pavement.

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