نشریه زمین شناسی مهندسی ایران
سال سوم شماره 3 (پاییز و زمستان 1389)

The study area is located 90 Km south-west of Qazvin in the structure zone of central Iran. The rock units of the area are comprised of a vast variety of carbonate, clastic and pyroclastic rocks, with age of Cambrian to Oligomiocene, that have significantly outcropped in the area. This research is based on assessment of 369 springs around the Avaj-Abegarm region. 23 of them are karstic springs that are located in the limestone of Qom formation, Lar formation and the limestone of Cretaceous. The discharge variation of these springs is affected by lithology, degree of crushing and tectonic fracturing, degree of karstification of carbonate rock, amount of precipitation and type of aquifer in the region. Based on chemical analysis done on 5 samples that were taken from large karstic springs in the area, the type and facies of spring's water are sodium-bicarbonate and sodium-chloride. Hydrochemistry of karstic aquifers in the area is influenced by solubility of carbonate rock of Qom formation and Lar formation, surface recharge from Upper red formation mixed with upwelling of deep brine in Cretaceous carbonate rock that probably have hydrothermal geneses.

Natural disasters such as landslides cause a significant loss of properties, facilities, and lives. The recent researches and the consequent development in the approaches to such disasters have proven that prediction of the time of failures might become possible. The more sophisticated techniques in time prediction of the landslides became the effective measures in the disaster management strategies.
There are several variable ions in the chemical composition of soils resulted from the weathering of geological units. The groundwater flow in the direction of hydraulic gradient throughout the soil may wash these ions further down within the soil. This process will reach to equilibrium between the chemical composition of the inflow water and soil ion exchange capacity, and thus, the concentration of onions and cations of the outflow water will remain constant. When the soil of sliding surface suffers a rupture, the textural uniformity and thus, the concentration of the ions will experience a meaningful fluctuation. Monitoring such remarkable change may become a valid factor in the development of early warning systems over the landslide prone slopes. In this research a physical model is designed and applied to put this hypothesis into a real test. Through the test period, the cation concentrations of Sodium, Potassium, Magnesium, and Calcium were carefully monitored against the process of slope movement. The results show that by recognizing and monitoring the concentration of the cations specific to the local soil composition to detect the cation variations in the outflow water from the slope might be the new economic approach to the prediction of the landslide timing.

The Sorkhab sub basin on Dez dam watershed is prone to landslide because of geological formation, topography and slope and accelerated erosion .Hazard assessment is necessary to mitigation of disasters and landslides vulnerability. For this purpose, were assessing several methods including modified Mora & Varson , modified Nilsun, Cupta-Joshi, two variate statistical method and information value and area density method.
The survays show litology, slope, distance to faults, and landuse are main factors in occurrence of landslide in area. As such more of 41 percent of areas fall into the high susceptibility zones. statistical methods for information value is more disirable Hazard zonation method for This basin.

In studies of mechanical and hydro-mechanical behavior of rock joints, it is important to consider the joint surface geometry. Statistic methods are used for quantification of rock joint surface geometry. In these methods the geometry of joint surface are quantified by Centre Line Average height (CLA), Root Mean-Square of height (RMS), Auto Correlation Function (ACF), RMS of the first derivative of profile (Z2) and Relative Length (RL). In most of previous studies, one parameter (such as Z2 or RL) was used for quantification of surface roughness. In this study, the efficiency of statistical parameters for rock joint quantification is evaluated. With this regard, Barton’s profiles and some profiles with regular geometry are used. Each profile is digitized and statistical parameters are computed. It is revealed that in order to study the rock joints behavior, it isn’t appropriate to use one or some limited number of statistical parameters.

Land subsidence caused by heavy exploitation of groundwater is an acquaintance morphological phenomena occurrence Iran. Recently the areas involved with this phenomena has been rapidly increased, covered most part of Iran’s areas from desert land in center to semi moisture areas in west and north-west. This is mainly due to saver frequency drought occurred during last decade. The wide distribution of land subsidence occurrence over residential areas has brought serious problems and damage which appeared this phenomenon in form of Geo-Hazard for the country. As the most part of the areas involved with land subsidence are located in a high seismic zone, the simultaneity of land subsidence with earthquake occurrence can inclemently increase individual damage from each and converting these events to the disaster. The present research deals with lands subsidence areas identification and mapping for disaster evaluation over the counter. In other to extract the land subsidence vulnerability and hazard over the Iran’s areas, the land subsidence outcome map was superimposing with settlement and infrastructure distribution map. In the next step, the vulnerable residential and infrastructure areas where overlaid with seismic hazard map to estimate and predict probable disaster. Thus, to mapping land subsidence over the country, the 18 areas where reported as land subsidence prone areas has been extracted from previous studies, where in 15 more areas the phenomena was measured using Differential Interferometric Synthetic Aperture Radar- D-InSAR techniques. The result of superimposing land subsidence map with seismic zonation map of Iran showed most land subsidence areas are located in a high hazard seismic zone. The reach outcome also shown earthquake occurrence over the land subsidence prone area can be a trigger for land collapsing over residential area, which can make double disaster. Moreover, land subsidence hazard can cause flood hazard over the residential areas where are not involved with this hazard so far. This is because of changing the river bed morphology and land downfall due to subsidence phenomena.

Remarkable set of features havecaused of widespread applications of artificial ligthweight aggregates. According to their application in various industries, the mechanical properties of these aggregates are important. Due to the absence of bedrock, determination mechanical properties of artificial ligthweight aggregate have special complexity.Ligth expanded clay aggregate (LECA) is the only industrialized ligthweigth aggregates that use in structural concrete in our country at now, which are produced with different density. In this research, to determination the diameter effect on the specific gravity, water absorption, resistance to abrasion, impact and pressure, various tests have been done on four size of structural Leca. Since there is not a standard procedure to determine the elastic modulus of ligthweigth aggregate, the combination of experimental methods and theory of composite material is used to estimate this parameter. With the combination of ligthweigth aggregate and cement-sand mortar (matrix), cylindrical composite specimens with 30% and 40% volume fractions of aggregates were cast and their elastic parameters of them are determined. Then with differential method and using elastic parameters of composite specimens and matrix, elastic modulus of ligthweigth aggregates is calculated. Test results indicate a significant effect of the grain diameter on mechanical propertiesof aggregates which produced with the same condition.

The investigation and estimation of surface subsidence and ground settlement is an important aspect in the design of shallow tunnels in urban areas. Proper exploration could lead to correct measures and avoiding any damage to structures over and underground.
In this study, four sections of the east-western part of Tehran’s Metro Line 7 with the most potential for surface subsidence were chosen and studied. This part of the metro project is positioned in the young alluvial deposits of Tehran and consists mainly of fine grained soil. Ground settlement requires three dimensional design. Hence, FLAC 3D was used to investigate the surface subsidence of the ground along the tunnel route in sections mentioned above. One of the most important advantages of three dimensional design is the possibility of stepwise excavation, and to explore the effect of each excavation step on the surrounding ground. Hence, the stepwise excavation was carried out and continued in 1.5 m advancing stages, until the advancement stopped affecting the ground settlement at the point over the tunnel portal considered in the model.
Even though, analytical and empirical methods are unable to evaluate the effect of ground water and the effect of overburden due to the presence of structures and traffic at the surface, because of not installing the monitoring system, analytical methods suggested by Sagaseta, Loganathan and Poulos, Verruijt and Booker, and Bobbet, and also Peck’s empirical method were used to investigate the ground settlement in this project.
After using the various methods to study the four chosen sections of the metro line, and analyzing the settlement curves in these sections, it was concluded that the ground settlements is permissible (except the second section).