PERFORMANCE ANALYSIS FOR TUNNELING PROCESS IN ROCKS USING FINITE ELEMENT METHOD

Abstract

In this research study, The prediction of the stress behavior and the effect of ground motion for applying the tunneling machine during the drilling process. A numerical model was developed for a tunnel project in Sulaymaniyah Governorate. For this purpose, a file of site investigation has been used for the rocks, which is the Hassan Kanoush Dam Project. The main objective of this study is to investigate the pressure behavior, stress ratio and determine settlement in the study area using the finite element method, and evaluate and determine the effect of a distance to move the drilling mechanism and progress to the rocks. The model is operated as three dimensional in drainage into clay stone rock and is filtered by using the applied Hoek-Brown model. Results are shown in terms of depth of stress curves. Those total vertical and horizontal pressures. Changes in stress conditions compared to rocks at the site are taken into account. Three vertical sections are select to study the effects of the TBM tunnel on the surrounding rocks. The first section (x = 0) passes through the center of the tunnel. The second section is located near the side edge of the tunnel, while the third section is chosen approximately off the edge of the tunnel. It is believed that the details mentioned in the analysis will provide a complete view of the pressure change in the rock. The strains caused by a boring process are presented differently and simply. This method reflected the movement of the rocks II and the stability of the rock surface. The deflected shape of the tunnel is also shown. By performing an axial symmetric FE analysis, calculation results revealed significant pressure changes occurring in rock regions near the tunnel boundaries. In other words, proximity to rocks is mostly affected by the tunnel. The stress effect fades for both diameters for the side of tunnel(1.33-2)D, in the top of tunnel (0.167-0.5)D, and in the lower of tunnel(2.92-5)D. All changes in the state of stress compared to the insite rock depend on rock profile in site. The highest surface settlement is observed immediately above the tunnel due to processes of TBM excavation which formed the first phase of the tunnel method. The behavior of surface settlement curve depends on the nature and shape of rock position layers. For other phases, the surface settlement is observed during tunnel construction phases, where it slowly decreases or converges when it is away from the drilling zone which established these TBM advancement phases since the distance is equal to 1.5 m. The maximum depression is recorded as the approximate top of the tunnel being 0.045 mm (diameter 6 m) and 0.16 mm (diameter 12 m).