فهرست مطالب mohammad hasan baziar

Observing destroyed engineered structures and induced fatality due to faulting motivated engineers to consider possible solution for reducing damage to structures. Mitigations countermeasures should be applied when elusion is not possible. Finite element analyses verified through centrifuge model experiments is implemented in this study. Considering different fault dip Angel, critical position of surface foundation in which it has the most rotation is specified. Then effectiveness of trenching a wall filled with extended polystyrene sheets (EPS) near foundation, at sufficient depth to intercept the propagating fault rupture is investigated. The results indicated that such wall thanks to its high deformability and very low shear resistance relative to the soil can absorb the compressive thrust of fault and forces the rupture to deviate along its length. So the foundation will experience less rotation and displacement .The effectiveness of EPS wall is depend on exact location of foundation relative to the surface fault outcrop s/b , magnitude of fault offset h/H and of course amount of fault dip slip Angel α.

In many cases, tunnels that are considered critical underground infrastructure for urban transportation are built in high seismicity areas and active fault zones. Fault displacements during earthquakes may interact with sub-surface structures leading destructions. Recent earthquakes, such as the 1999 earthquakes in Turkey and Taiwan, revealed that by avoiding construction in the fault zone, the structures are not completely safe for fault threats. Therefore, it is necessary to evaluate the interaction mechanism between structures and fault rupture for effective design to reduce the hazards associated with surface faulting. Verified finite element modeling is used in this study to investigate normal fault-tunnel interaction. The effect of different parameters such as horizontal tunnel distance relative to rupture path in free field condition, tunnel depth, tunnel rigidity, and fault angle on fault–tunnel interaction are studied. The results indicated that the tunneling in the path of fault rupture causes a diversion of rupture path. The burial depth of the tunnel and its diameter are effective parameters in the propagation of the shear zone in the sand layer and surface deformations. With increasing the tunnel depth, the rupture path inclines more, and the shear zone is extended over a wider area. Comparison of numerical results demonstrated that surface displacement in normal fault of dip angle 45° is higher than 60°.

The load response and carrying mechanism of piles in a non-connected piled raft foundation is a complex phenomenon due to complex soil–structure interactions such as interactions among piles, subsoil, cushion, and raft. The scope of this research includes four main components: (1) using 3D finite element modeling and verifying different models with centrifuge tests; (2) investigating the parameters affecting the axial stiffness of a non-connected piled raft; (3) investigating the influence of different parameters on the foundation settlement; and (4) devoting special attention to the mechanism of carrying and sharing loads as well as the load–settlement behavior of non-connected piled raft foundations, in comparison with connected piled raft foundations. Results of this research showed that in order to achieve optimal design, geotechnical designers should consider three major factors, including axial stiffness of non-connected piled raft, settlement, and stress along the pile length.

Location of floating piles is one of the main factors influencing on their optimal performance with respect to slope stability improvement. Many studies have been devoted to this concern using different analytical methods. Due to the importance of this issue in seismic conditions, still more studies are necessary and therefore, the location of floating piles has been investigated in this research using finite element method under seismic conditions. Three parameters including soil arching, crest settlement and pile bending moment has been considered in investigations. Using load transfer factor, soil arching can be suitably quantified and then utilized in numerical analyses. A comprehensive coupled numerical analysis has been carried out in order to examine the optimal location. With the purpose of considering soil's increasing elasticity modulus in depth, a FORTRAN code was developed. To obtain authentic results, modeling has been verified by comparing numerical results with an experimental research which was performed previously. The results showed that the optimal location which causes the highest stability level is the first middle of up-slope (XP/LH = 0.5 - 0.75).