Ground Settlement Model for Excavation of a Non-Partial Pressure and Shallow Buried Double-Arch Tunnel
The ground settlement model due to tunnel’s excavation was summarized in this paper. Firstly, the geological characteristics of a double-arch tunnel in Jinliwen Expressway are investigated and analyzed, which mainly act as discontinuity. Especially, settl
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GROUND SETTLEMENT MODEL FOR EXCAVATION OF A NON-PARTIAL PRESSURE AND SHALLOW BURIED DOUBLE-ARCH TUNNEL Jihong Wei Civil Engineering College, Hohai University, Nanjing 2JO098,China Shaorui Sun Geotechnical Engineering Research Institute of Hohai University, Nanjing 2JO098,China The ground settlement model due to tunnel's excavation was summarized in this paper. Firstly, the geological characteristics of a double-arch tunnel in Jinliwen Expressway are investigated and analyzed, which mainly act as discontinuity. Especially, settlement pattern during excavation of such a double-arch tunnel with non-partial pressure and shallow bury was taken out by data analysis from those monitoring information. After ground settlement model and its increment model following the each step of tunnel's excavation were built, the difference offorecasting between single tunnel and double-arch tunnel was shown. Secondly, the ground settlement model was testified by comparing between forecasting and field data. Thus, theoretical basic to avoid overmuch settlement during excavation of such a doublearch tunnel was provided. INTRODUCTION
The ground settlement due to tunnel excavation was researched by experience equation, theory analytical solution and numerical simulation etc. The Peck method was a representation for experience equation method. Within Peck method, the mechanics characteristic of surrounding rock was clearly discussed when it is used to evaluate the ground settlement due to tunnel excavation. However, the result mainly depending on one's experience may cause great difference contrast to the in-situ measurement. The surrounding rock is regarded as elastic, elastic-plastic or creep-elastic-plastic media in the theory analytical method. The numerical simulation might be taken the construction process into account from different angle. Double-arch tunnel is a good type used in construction of expressway. Otherwise, special requirement ofthe stability ofsurrounding-rock was required due to the typical special structure. On the other hand, because of the complex construction process, many geological problems were inevitably faced and maybe only parts of them could be solved. The ground settlement model for excavation of the non-partial pressure and shallow bury double-arch tunnel in Jinliwen Expressway was researched in this paper. According to the theory analysis, the ground settlement model was built and used for monitoring and forecasting.
RESEARCH DEVELOPENT OF GROUND SETTLEMENT At present, research on the ground settlement model mainly concentrates on those excavations in city. Therefore, many ground settlement models, such as Peck equation and revised Peck equation , were built in soft soils. Based on a large number of data for settlement monitoring, calculating equation of cross section settlement was put forward by Peck in 1969. According to measure and calculation in field, the limitation for Peck equation is analyzed by Celestino. The results showed that the cross section settlement is not normal distribution curve when
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