Study On Controlling Technique For Influence On Environment During Construction Of Urban Neighborhood Tunnel

With the rapid development of national economy and gradual increasing of the urban population, a large number of urban tunnels need to be built in order to alleviate the traffic pressure. It proposes high requirements on neighbor tunnels about how to control environmental impact during the construction process for urban space resource is limited and surrounding environment is very complicated. Therefore, we should control the settlement of the building when one tunnel is excavating under the building and vibration of the linings caused by blasting. The research background in this paper is Wucunshan tunnel on JC3 bid section of airport Highway in Xiamen. As a shallow-depth large-scale neighbor tunnel, Wucunshan tunnel locates in complex geological condition and goes through dense buildings, and has much difficulty in construction including building settlement control and blasting vibration control. Based on Wucunshan tunnel, building settlement control and blasting vibration control during the construction process of urban neighbor tunnel was systematically studied by theoretical analysis, numerical simulation and in-situ measurement, and some inclusions were obtained as following:(1)This paper analyzed and summarized the key factors of building settlement and control technology. Several common control measures were numerically simulated and comprised, which could provide reference for choosing good scheme. As the tunnel excavation is a dynamic process, dynamic tracking grouting is proposed based on static control measures, and the mechanism and characteristic of grouting uplift is analyzed.(2) The project practice of Wucunshan tunnel indicates that grouted roof pipe and full face grouting has a better control effect to the settlement of the building and reasonable construction sequence is conducive to control the differential settlement of the building. And comparative analysis of practice and monitoring shows that the dynamic tracking grouting is a good control method, in particular, surface tracking grouting is better than inside tracking grouting. Therefore, this paper suggests adopting surface tracking grouting as far as possible if the settlement should be strictly controlled and there is enough ground for surface tracking grouting, and analyzes basic conditions which should be satisfied in order to achieve effective uplift.(3)The effect of the later hole's blasting on the first hole was numerically simulated in urban neighbor tunnel. Two-dimensional simulation studied different effect of blasting vibration on lining when different support state of the first hole, different excavation method of the back hole and different distance of two holes. Three-dimensional simulation analyzed the longitudinal effect of blasting vibration on lining, and suggested reasonable time to pour secondary lining.(4) According to historical documents, the paper analyzed and summed up the detailed effect of blasting vibration on the structure. The spread formation of blasting vibration in the stratum was regressed based on monitoring data, which can provide reference for blasting scheme. In order to ensure the safety of the surface buildings, the original blasting parameters were optimized now that the depth is gradually decreasing, as a result, the blasting vibration rate was successfully controlled below 1 cm / s.