PREDICTING MOVEMENT OF SOIL AROUND BAGHDAD METRO UNDER BUILDINGS LOADS USING THREE DIMENSIONAL NUMERICAL SIMULATION

One of the most widely risks in tunnelling in urban regions is the excavation under urbanized constructions. The loads of these constructions are considered as surcharge loads applied at the ground surface. Existing of such surcharge loads leads to increase the stresses and to change all field variables in medium during and after tunnel construction. It is significant to predict the ground settlements and the displacements of soil surrounding around tunnel at sites where buildings, rivers, etc. exist or may be existed in the future. In this paper, movement of soil around Baghdad metro are predicted at location, its coordinates are 443954.463 m for X and 3688861.836 m for Y, in which buildings with medium heights are found basing on numerical simulation method. The commercially available finite element package, Abaqus 2016, is used to simulate Baghdad metro at this location. A series of actual tunnel process is simulated using a fully coupled three dimensional stress-pore pressure finite element model to realistically capture the mechanical and hydrological interaction between tunnelling and ground water. Then, the vertical displacements of soil surrounding around Baghdad metro at that location are computed through the time periods of three sequential simulation steps. These steps are named as the excavation, linings installation, and consolidation steps. It is found that maximum vertical displacement occurs at the crown to the downward with value equal to 3.8 m approximately after linings installation immediately. Practical implications of the findings from this study are also discussed.