Study On Site Monitoring And Optimization For Mid-partition Of Double-arch Tunnel

Since reform and opening, the road traffic of China increased quickly. The separation tunnel and neighborhood tunnel of traditional can not meet the traffic demands, so the arch tunnel has emerged in this case. For the arch tunnel starting late in our country,its design and construction methods do not immature. As the important part of the arch tunnel——-middle wall, the experience learns from the design and construction of less. The middle wall designs reasonably or not, related to the middle wall's steady or not.So it needs to combine practical engineering example and systematic study the force of the middle wall.Based on Sha Tangkeng tunnel in Erguang highway consrtuction-in-progress, this paper according to the design and construction methods used in construction and support measures,adopting theoretical review and numerical simulation method,combined with the analysis of field experiment,a series of researches are carried out to the middle wall.Firstly, according to the relevant mechanics of arch tunnel, determines the calculation of rock pressure. As the calculation of the pressure for deep and shallow tunnel is difference.Therefore, we must be covered under the tunnel layer can form a "natural arch" to carry out deep tunnel or shallow tunnel, and then calculates the corresponding rock pressure.Secondly, summarizes the in-site monitoring aim and meaning, introduces the content and attention which is often used in field experiments and then plots the curve through the measured date. On this basis, selects the monitoring data of typical section for the clearance convergence,crown settlement rock pressure and the inner force of anchor to study, and analyzes the monitoring results of the wall stress and displacement. The results shows that:the characteristic value is larger than normal, the unusual results appears in turn that the arched tunnel wall symmetry at the guide hole in bias conditions setting causes its unevenly stressing.Finally, applied ANSYS finite element analysis software to numerical simulation for the middle wall setted symmetry in central drift and the middle wall was translated to the deep side of the tunnel for one meter and other structural unchanged. From the view of the stress and strain, the middle wall was translated to the deep side of the tunnel for one meter, the asymmetric pressure of its two sides will reduce greatly, the stress and strain produced for the middle wall reduces significantly. So the stress of middle wall is more reasonable and the stability of the middle wall is better.