A Study On Separation Effect For Adjacent Highway Tunnels With Eight Lanes Using Laboratory Test And Field Test

In the narrow hilly terrain areas or construction sites matching with roads and bridges, neighborhood tunnel is one of the most widely used form. so far, there have built some neighborhood tunnels home and abroad, mostly two-lane or three-lane, the single hole span is within 15m. With the increasing traffic volume, two-hole eight-lane highway tunnel have being built gradually. Its single-hole span is up to 20-23m, while the maximum height is about 13m. The section appears a serious flat shape, the stress and deformation are more complex, and the interaction is serious in the case of closely excavated. Until now, the number of two-hole eight-lane highway tunnel is very small, the concerning research and technologies are also very limited, besides, the existing specifications of road tunnel design and construction are not related to the kind of tunnel. It is of great significance to research the two-hole eight-lane highway tunnel systematically.This thesis investigated the mechanical properties of the fifth two-hole eight-lane highway tunnel in china by applying the laboratory test, field test and numerical simulation, based on the design and construction of Xinwu tunnel of Shenzhen Nanping expressway (second stage). The work done and major achievements are as follows.(1) This thesis investigated the support deformation features and structural internal force and analyzed the development law of deformation and force in the condition of different spacing, and determined the minimum reasonable clear distance of small interval tunnel in IV surrounding rock, based on eight groups small interval model test.(2) This thesis researched the failure mode and ultimate bearing capacity of tunnel support in different spacing, and summarized the characteristics of tunnel support failure.(3) Through field tests, this thesis researched the effect, which is Produced from excavation in the first hole, to support force in the underwent hole, and summarized the effect range and force distribution characteristics.(4)The model test and field test results were compared with validation and additional analysis by numerical simulation.