Investigation on the Liquefaction of a Clayey-Sandy Soil During Changureh Earthquake

An intense earthquake (MW = 6.4) occurred in western Iran, about 225 km west of Tehran at 7:28 local time, June 22, 2002. Surface soil in this area is mostly clay; however, clear traces of sand boiling, softening of soil, and consequent deformations were observed particularly in Hessar village. Some soil samples were prepared throughout an excavated pit from a depth of 2 m, the depth of the liquefied layer. The preliminary tests showed that the soil has a liquid limit of 38, a plasticity index of 18, and a \u3c No. 200 fraction of 44%. These index characteristics would indicate a nonliquefiable soil according to the commonly used criteria. Analysis of cyclic triaxial test data suggests that the clayey sand deposit likely developed high residual excess pore pressures and significant shear strains during the earthquake and thus likely contributed to the observed lateral deformations. In this paper, different cases of observed liquefaction and consequent geotechnical phenomena are presented. Moreover, the results of laboratory tests on reconstituted samples are presented to prove how a soil with 44% of clay content could be liquefied

The Effect of Irregular Seismic Loading and Soil Density on the Liquefaction Behavior of Saturated Sand

Structures located on sandy soils can be significantly damaged by earthquake-induced liquefaction. A series of stress-controlled cyclic triaxial tests under harmonic and irregular loading under various soil densities 30%, and 50%, was conducted to evaluate the effects of irregularities and relative densities on the liquefaction characteristics of saturated sand. The irregular actual ground motions time histories obtained from six stations of the 1999 Chi-Chi Earthquake and harmonic sinusoidal cyclic loading time histories were applied to Firoozkooh #161 sand specimens, and the results were compared in terms of the type waveforms loading and relative densities. Based on the stress and energy method, the Correction coefficient is calculated for a variety of densities and types of irregular loading. The present results reveal that it is not precise to assume a single correction coefficient for all records, regardless of the complicated time-domain characteristics of ground motions. Furthermore, the results indicate that the relative soil density and the type of irregular loading influenced sand's pore pressure generation and liquefaction potential

Mitigation of Seismic Deformation of Anchored Quay Wall by Compacting

The anchored quay walls or bulkheads are commonly used in coastal areas. Previous studies on the seismic behavior of these quay walls have shown a significant effect of the liquefaction on the performance of the walls. Considerable length of an anchored sheet pile wall in Rajaii port, Iran, has been embedded in liquefiable sand. This study tries to clarify failure mechanism of the wall during earthquake and to identify more effective zone for improvement of the wall stability. Numerical modeling by DIANA software and physical modeling by shake table were presented. Results show that the main reason for extensive deformation of the system is the liquefaction of the soil adjacent to the root of the wall. The compaction of this zone improves the performance of the system and prevents large displacements. The mitigation plan was proven by comparison among the measured results, including the final shape, displacements and excess pore water pressure ratio

2003年バム地震におけるバム市内の地盤と基礎構造の挙動

Following the devastating earthquake disaster in Bam city, Iran, a reconnaissance team was sent to the site. The authors participated in its activities with special emphasis on geotechnical issues. A soil investigation in the city revealed that local soils have su$ciently good properties and cannot be the main source of heavy damage to houses. Because bridges and structures other than buildings experienced minor damage during the same earthquake, it seems that the structural weakness of houses made of masonry and adobe is a major problem. A possible mitigating measure may be to use light materials such as ESP, although consideration has to be given to the local climate and the landscape

Time-Dependent Probabilistic Seismic Hazard Analysis Using the Simulated Records, the Case of Tehran

Common attenuation equations are developed by seismic records which belong to earthquakes that have happened so far. Although there are many recorded data during last 50 years, it is not possible to consider all possible wave propagation paths, site types and fault rupture mechanisms inclassical attenuation relations. This fact becomes more serious in near field cases and a common shortcoming in most attenuation equations is their low accuracyin estimation of near field parameters.Many important cities of the world such as Tehran are located nearby some active faults. For example, the North Tehran Fault is such a closeseismic source to Tehran Metropolitanarea andcould be considered asa near field source. Therefore, it is necessary to evaluate near field effects in most of hazard analyses, risk management programs, structural designs, etc.In past, it was routine to use attenuation equations in hazard analyses. In this project for avoiding from insufficient performance of attenuation equations in near field, proposed simulation datum byZafarani, et al., (2012), were used directly in the hazard analysis without converting them into attenuation equations.Besides, time dependent hazard analysis (Non-PoissonianModel) was used to taking into account the probable seismic activity of the North Tehran Fault

Seismic Behavior of Local Soil and Foundations in Bam City During the 2003 Bam Earthquake in Iran

Following the devastating earthquake disaster in Bam city, Iran, a reconnaissance team was sent to the site. The authors participated in its activities with special emphasis on geotechnical issues. A soil investigation in the city revealed that local soils have su$ciently good properties and cannot be the main source of heavy damage to houses. Because bridges and structures other than buildings experienced minor damage during the same earthquake, it seems that the structural weakness of houses made of masonry and adobe is a major problem. A possible mitigating measure may be to use light materials such as ESP, although consideration has to be given to the local climate and the landscape