ميرمهدي راشدي

Permanent ground displacement due to faulting during strong earthquakes threatens stability of civil structures. To protect surface foundations from faulting, several mitigation techniques have been developed. The results of this study indicate that previously suggested methods, such as the presence of a weak wall next to the foundation or a strong inclined wall beside a weak vertical wall, are not suitable for unknown fault conditions, and the foundation rotation may be the same or worse than an unprotected foundation when the worst-case scenario of the discontinuity location and dip angle of the fault exists. Due to limitations of earlier mitigation strategies for unidentified reverse faulting conditions, this research presents a novel mitigation system, including installing sliders beneath the wings of a V-shaped concrete element, to reduce footing rotation. To eva‎luate the effectiveness of the suggested mitigation strategy, concrete strength tests, a physical centrifuge test and a comprehensive numerical study for different fault locations and dip angles were conducted for the first time. Results demonstrated that the placement of the sliders beneath the V-shaped wings had a significant effect on dissipating the fault dislocation. Compared to the previous mitigation techniques, the proposed system decreased the foundation rotation from a high value (11o) to a low value (3.2o) for the worst-case scenarios. Furthermore, a centrifuge test and comprehensive numerical modeling were carried out in three-dimensional conditions to investigate the shallow foundation rotations along three axes under reverse faulting. Results showed that the bearing pressure beneath the footing and foundation rotation along different axes are severely dependent on the fault characteristics, including fault trace angle with respect to the footing axes and also faulting positions. In other words, footing may rotate along different axes due to the crossing oblique fault trace, which cannot be observed in two-dimensional modeling. Finally, a three-dimensional form of mitigation strategy for shallow foundations, as a pyramid-shaped concrete element with sliders beneath its faces, is introduced.

گسلش معكوس , قطعه به شكل هفت با لغزنده ها در زير بال ها , گسلش در شرايط سه بعدي , مدل سازي آزمايشگاهي , مدل سازي عددي

Reverse faulting , V-shaped concrete element with sliders , 3D fault-foundation interaction , Experimental modeling , Numerical simulations

Mir Mahdi Rashedi

Mohammad Hassan Baziar