The Deformation Control Technology Of A Neighboring Subway Bridge Affected By Large-diameter High-speed Railway Shield Tunnel Under Different Protective Measures

With the rapid development of China ’s economy and the large-scale construction of high-speed railway and subway,these two modes of transportation will inevitably cross.Different from other adjacent building projects,the construction of adjacent subway bridges needs to take certain protective measures to ensure the safe operation of existing lines.Since the process flow and characteristics of protective measures are different,the scope of application of different protective measures is different.Therefore,it is necessary to study the reinforcement effect of different protective measures,so as to put forward reasonable and effective protection scheme for such projects.Taking a large diameter shield tunnel of a high-speed railway in Beijing(the outer diameter of the shield segment is 12.2 m)adjacent to the existing subway bridge(the net distance between the outer edge of the tunnel and the bridge cap is 14 m)as the research object,the threedimensional numerical simulation analysis method and engineering monitoring method are used to systematically analyze the effects of different protective measures.The main research contents are as follows.(1)The influence of protective measures parameters on the reinforcement effect is compared and analyzed,and the reasonable reinforcement scheme is put forward: The process and characteristics of common protective measures(bored pile protection,composite anchor pile protection,sleeve valve pipe pre-grouting isolation protection)in crossing engineering are summarized.This paper systematically analyzes the engineering background,determines the model parameters,simulates the construction steps,analyzes the influence of protective measures parameters on the reinforcement effect,and obtains the range of protective measures parameters for this project.(2)Comparative analysis of construction monitoring data and digital simulation results: By comparing the monitoring data and digital simulation results,and according to the characteristics of the crossing project itself,the difference of the influence of different protective measures on the existing structure is analyzed.The monitoring results of the typical stage are compared with the numerical simulation results to verify the reliability of the model.three row anchor pile and drilling pile isolation effect is equivalent.The isolation effect of door pier scheme is better than other schemes.(3)The protective measures for the shield tunnel adjacent to the subway bridge in this project are clarified.By comparing the influence of shield tunnel construction on the existing bridge structure under different buried depths and different net distances,isolation measures of shield tunnel adjacent to metro bridge in this project are obtained.For special risk points such as station to interval and subgrade to bridge transition section,it is necessary to strengthen isolation measures to control differential deformation.