Evaluation And Research On The Influence Of The Wei Qiang Coal Mine No.1 Pane Mining On Majiapangou Bridge

The impact of underground mining on bridges is one of the issues that h as been widely concerned at home and abroad in recent years,mainly because of the uniqueness of the bridge structure and its important significance in transportation.The construction and post-construction of Majiashipangou Bridge on National Highway 210 from Yuyang to Jingbian are affected by mining subsidence in different periods.It is of great significance for the safe operation of National Highway 210 to study the influence of the surface deformation of the Weiqiang Coal Mine mining on the Majiashipangou Bridge.Aiming at mining geological,mining and bridge engineering geological conditions,based on the analysis of bridge movement observation data,probability integral prediction,numerical simulation method and theoretical analysis method are applied to calculate and simulate the influence degree and damage characteristics of mining surface movement deformation on the bridge.By analyzing the monitoring data of the movement and deformation of the bridge under the influence of mining,it is concluded that the bridge has undergone the three processes of initial settlement-stability-against settlement,determine that the current bridge damage is far less than the level I damage;Aiming at the complex situation of highway bridge construction affected by mining subsidence in different periods during and after construction,the method of dynamic surface movement and deformation is used to predict and evaluate,and the current stage of the bridge and the residual movement deformation are obtained to provide a basis for evaluating the safety of the bridge.Using FLAC3D software to calculate and simulate the movement and failure law of overburden and the deformation of bridge piers,it is concluded that the underground mining caused the overburden and surface movement to go through three stages of inadequate mining-full mining-ultra-full mining,and it was determined that the mining of 1305 and 1307 working faces had a greater impact on the bridge.The maximum sinking value of the bridge pier reaches 44.5mm,but the difference of sinking value between the north and south ends of each bridge is not more than 2mm,and the bridge was in a state of uniform settlement;The maximum positive shear force acting on the pier is 1151.1kN and the maximum negative shear force is 3986.9kN.The force on the pier is within the allowable range,and it is determined that the pier has not been deformed under the influence of mining.Observation data analysis and calculation simulation results show that,as of now,the overall sinking of the bridge deck has reached a maximum of 43mm,the maximum horizontal movement value of the bridge deck has reached 54mm,and the overall damage degree of the bridge is within the level I;The predicted residual surface movement deformation is less than the allowable deformation value of simply supported bridge,and the damage to the bridge caused by the residual surface movement deformation is within the level-1 range.The theoretical analysis and numerical simulation methods were used to determine that the bridge foundation was in a stable state.The research results have important reference value for damage evaluation of highway bridges in mining area.