International Journal of Civil Engineering
Volume:8 Issue: 2, Jun 2010

and facilities. Although surface fault rupture is not a new problem, there are only a few building codes in the world containing some type of provisions for reducing the risks. Fault setbacks or avoidance of construction in the proximity to seismically active faults, are usually supposed as the first priority. In this paper, based on some 1-g physical modelling tests, clear perspectives of surface fault rupture propagation and its interaction with shallow rigid foundations are presented. It is observed that the surface fault rupture could be diverted by massive structures seated on thick soil deposits. Where possible the fault has been deviated by the presence of the rigid foundation, which remained undisturbed on the footwall. It is shown that the setback provision does not give generally enough assurance that future faulting would not threaten the existing structures.Ground differential movements due to faulting have been observed to cause damage to engineered structures

Mixed clayey soils occur as mixtures of sand (or gravel) and clay in widely varying proportions. Their engineering behavior has not been comprehensively studied yet. An experimental program, comprising monotonic, cyclic, and post-cyclic triaxial tests was undertaken on compacted clay-granular material mixtures, having different proportions of clay and sand or gravel. This paper presents the results of cyclic triaxial tests and explains the behavior of the mixtures based on number of loading cycles, cyclic strain amplitude, granular material content, grain size, and effective confining pressure. The results indicate an increase in degree of degradation and cyclic loading-induced pore water pressure as the number of loading cycles, cyclic strain and granular material content increase. Also the results show that the grain size has no significant effect on the degree of degradation and cyclic loading-induced pore water pressure in the specimens. The effect of granular material content on pore water pressure during cyclic loading in equal-stress-level was also examined. The pore water pressure increases with the increase of granular material content.

Investigating the parameters influencing the behavior of buried pipelines under dynamic loading is of great importance. In this study the soil structure interaction of the pipelines with the surrounding soil was addressed using shaking table tests. Wave propagation along the soil layers was also included in the study. The semi infinite nature of the field was simulated using a laminar shear box. The soil used in the experiments was Babolsar coastal sand (Iran). PVC pipes were used due to their analogy with the field. Eight models were constructed with the first four models having uniform base. In the next models, the non-uniformities of real ground were simulated using a concrete pedestal installed at the very bottom of the shear box. Pipe deformations under dynamic loading, acceleration distribution in height, soil settlement and horizontal displacements were measured by strain gauges, acceleratometers and displacement meters. Analyzing the obtained data, influence of different parameters of dynamic loading such as acceleration, frequency, soil density, base conditions and shaking direction to pipe axis on the acceleration amplification ratio and pipe deformation were investigated. Also in order to study the effect of dynamic loading on two different materials, soil and pipe, the horizontal strains were compared.

Considerations on the explosion resistant design of special infrastructures have increased in the recent years. Amongst the various types of infrastructures, road and railway tunnels have a unique importance due to their vital role in connection routes in emergency conditions. In this study, the explosion effects of a projectile impacting on a railway tunnel located in a jointed rock medium has been simulated using 2D DEM code. Primarily, a GP2000 projectile has been considered as a usual projectile and its penetration depth plus its crater diameter were calculated in rock mass. The blast pressure was, then, calculated via empirical formula and applied on the boundary of crater as input load. Finally, the wave pressure propagation through the jointed rock medium was investigated. In part of the study a sensitivity analysis has been carried out on jointed rock parameters such as joint orientation, dynamic modulus and damping ratio. Their effects on tunnel lining axial force as well as bending moment have also been investigated.

Seismic piezocone device (SCPTu) together with Resonant Column and Cyclic Triaxial test apparatus are employed to measure small strain shear modulus (G0) of carbonate sandy and clayey soils of southern coasts of Iran. A large area of southern regions of Iran is formed from clay, silt and sand. In this study, maximum shear modulus that is derived from both field (by seismic piezocone) and laboratory (by Resonant Column and Cyclic Triaxial) tests on soil samples from the southern region, indicated a meaningful effect of sample disturbance. Results show that in laboratory tests, loose samples tend to become denser and therefore exhibit greater stiffness whereas dense samples tend to become looser, showing a reduction in stiffness. According to the results of the present study, there are narrow limits of soils shear moduli for which the laboratory tests and the field measurements yield approximately the same amounts. This limit of shear moduli is about 30-50(MPa) for clay deposits and 70-100 (MPa) for sandy deposits. Since the shear moduli of soils in small strains can also be computed from the shear wave velocity, also correlations based on parameters derived from SCPTu test for shear wave velocity determination of sandy and clayey soils of the studied area are presented. This study shows that shear wave velocity can be related to both corrected tip resistance and total normal stress. The measurements of the damping ratio and shear module, because of a great disturbance of stiff deposits during the sampling process and also due to considerable differences between the laboratory and field results, by the laboratory approaches are not reliable and advised.

A semi-micromechanical multilaminate model is introduced here to predict the mechanical behavior of soils. This model is like a bridge between micro and macro scale upon the satisfaction of minimum potential energy level during any applied stress/strain increments. The concept of this model is based on a certain number of sampling planes which constitute the elastic-plastic behavior of the soil. The soil behavior presents as the summation of behavior on these planes. A simple unconventional constitutive equations are used in each of the planes to describe the behavior of these planes separately. An unconventional plasticity can predict the soil behavior as a smooth curve with considering plastic deformation due to change of stress state inside the yield surface. The model is capable of predicting softening behavior of the soil in a reasonable manner due to using unconventional plasticity. The influences of induced anisotropy are included in a rational way without any additional hypotheses owing to in-nature properties of the multilaminate framework. Results of this model are compared with test data and reasonable agreement is found.

Inclined retaining walls with slopes less than perpendicular are appropriate candidates in several engineering problems. Yet, to the knowledge of authors, only a few analytical solution for calculation of active earth pressure on such walls, which will be usually smaller than the same pressure on vertical ones, has been presented neither in research papers nor in design codes. Considering limit equilibrium concept in current research, a new formulation is proposed for determination of active earth pressure, angle of failure wedge and application point of resultant force for inclined walls. Necessary parameters are extracted assuming the pseudo-static seismic coefficient to be valid in earthquake conditions. Moreover, based on Horizontal Slices Method (HSM) a new formulation is obtained for determining the characteristics of inclined walls in granular and or frictional cohesive soils. Findings of present analysis are then compared with results from other available methods in similar conditions and this way, the validity of proposed methods has been proved. Finally according to the results of this research, a simplified relation for considering the effect of slope in reduction of active earth pressure and change in failure wedge in inclined retaining walls has been proposed.

Hydrologic Evaluation of Landfill Performance (HELP) model is one of the most accepted tools to simulate the hydrological attributes of landfills. Although some major deviations from real values has been reported about the calculated results for leachate generation by HELP model but other researchers and/or engineers in practice have used it in some places to estimate amount of leachate produced in the landfills. On the Other hand this model is elaborated and mainly used in developed countries with the waste having low moisture content and also in climatic conditions with high precipitation. This research investigated the applicability of the model in arid areas, by construction of two 30m× 50m (effective horizontal length) test cells in Kahrizak landfill (longitude=51°, 20'', latitude= 35° 27'' degrees), and monitoring the real leachate generation from each one. A set of field capacity and saturated water conductivity tests were also performed to determine basic hydrologic properties of municipal waste landfilled. A comparison was made between values calculated by HELP model and recorded values, shows that a prediction of leachate on annual basis can be done by HELP model with acceptable accuracy but when the infiltration of water to waste body increases due to leachate production, the model intents to underestimate water storage capacity of the landfill, which lead to deviation of calculated values from real ones.