ali mohammad rajabi

Investigation of the effect of temperature on soil strength is one of the issues which has been considered by many researchers in recent decades. In this study to investigate the effect of temperature on the undrained shear strength (Cu) of clay soils, a cell with the capability of both changing and keeping fixed the temperature of sample, was designed and constructed. After determining the index properties of samples for Kaolinite clay soil, undrained shear strength (Cu) test was carried out on saturated clay soil at 10, 20, 30, 40, 50, 60 and 70 ° C. Repeatability of the results was confirmed by repeating tests on samples with the same properties a given temperature. The results showed that by increasing the temperature, the Cu values decreased so that, as the temperature raised from 10 ° C to 70 ° C, the values Cu were reduced from 26.6 to 10.94 kPa. Accordingly, in the studied temperature range, an empirical relationship between temperature and Cu (with R2= 0.96) was proposed. The general shape of the stress–strain curves of the samples in different temperature was the same and in strain level of 20% was linear. Increasing the temperature caused to decline in the range of elastic deformation and enhancement in the range of plastic deformation of the samples; in addition, by increasing the temperature, the angle of the failure plane was decreased. The measurement of axial expansion stress (AES) indicated enhancement of the stress by increasing the temperature.

Liquefaction is a serious natural hazard in susceptible regions which are prone to earthquakes. According to empirical and field studies, insufficiency of liquefaction assessment methods in determining liquefaction through clays and high prediction errors has caused an unceasing new development. In this article we present a comprehensive history review to organize literature on the liquefaction potential evaluation published prior to 2017. We consider deterministic approach based on SPT (Standard Penetration Test) records to create an appropriate connection between the different methods, facilitate reviewing the development of correlations in the past and current decades, assess both the cyclic stress and the flow liquefactions in a unified system, compile the latest research developments and identify the main sources as a database for the future investigators. The study attempts to assess cyclic stress method (1971) and Chinese criteria (1982) in evaluating the liquefaction potential and to discuss the insufficiencies of these methods with reference to the liquefactions caused by the Chi-chi (Taiwan) and Adapazari (Turkey) earthquakes in 1999. Besides, the absence of soil improvement on the basis of vulnerability and performance is identified as a research gap in this study.

Nowadays, Zonation Maps can be used as a main guiding document, control and supervision of construction and building in urban areas. Using these maps prevents the unnecessary interference and inappropriate land uses and improving the quality and efficiency of the urban Areas. Great efforts are done to develop zonation maps such as earthquake hazard zoning, determining the occurrence of earthquake hazard with different probabilities including landslide and liquefaction hazard zoning. Using these maps, depending on the type and objectives based on existing standards and extensive data bases, we can reduce costs and increase the speed of decision-making engineering judgments. Qom as a populated city of the country, due to the extending and increasing of development activities on the one hand and the sources of risk, including Khedher and Qizqaleh faults undoubtedly is subject to geological hazards such as earthquakes.
In seismic microzonation studies, estimating the velocity of seismic waves in soil layers is very important to be evaluated directly and indirectly. Dynamic probing test is one of the indirect methods for evaluating shear wave velocity.
Since the relationship between the shear wave velocity and the experimental results of the dynamic probing test has not been used to compile zoning maps, so far, in this study, the results of the dynamic probing experiments have been used to estimate the wave velocities of soil layers in some areas of the city. Using geotechnical data and 3500 dynamic probing tests from 650 boreholes in 250 different locations in Qom and also using the relationship between calculating shear wave velocity and dynamic probing test results, shear wave velocity profiles at depths up to 30 meters was produced, and development of land zoning map based on the 2800 standard in the range of Qom, is considered. The results of this research indicate that most of the soils of the Qom area up to a depth of 30 meters are silty fine grains. Except for the part of the northern and southern regions of the study area, soil type is type 3 with a mean shear velocity of 375-500 m/s. The proposed zoning map with acceptable accuracy in order to reduce costs and increase the speed of decision making in engineering judgments for site classification, seismic analysis and seismic design of structures of medium importance in alluvial zone The city of Qom is widely used. It should be noted that site specific studies should be carried out separately for sensitive buildings such as hospitals and medical centers, and the cases mentioned in part 5-4-2 of Iran's 2800 Code, fourth edition.

Nowadays, development of the industrial societies and urbanization caused the daily rising accumulation of plastic waste and their dispersion in the nature. To decline the environmental issues of this phenomenon, different approaches are possible. The possibility of reusing plastic waste in new structure of the soil has been studied in this research. For this purpose, samples of sandy soil with dry density 1.7 gr/〖cm〗^3 and waste plastic pieces (made from mineral water bottles) with 8 × 12 mm in size(weight proportional of 0.3 %) have been mixed. Then direct shear test with fast and slow speeds 1 and 0.3 mm/min respectively in two small and large scale (10×10 and 30×30 cm, respectively), have been done in saturated condition. In the next stage, 5% of cement slurry has been added to this mixed soil and the previous tests have been repeated. The results show that adding waste plastic pieces to the sandy soil, leads to increasing the total friction angle and finally shear strength. So, for mixed soil plastic waste and cement slurry in comparison to soil without cement slurry, despite of reducing of the internal friction angle, shear strength increases from 20 to 30 percent due to significant increase in the cohesion.

Analytical results of 11 groundwater samples are used to evaluate the quality of groundwater in the Hastijan area, (Central province –Iran). The main indices of water, ions physicochemical characteristics and the important heavy metals concentration studied. to estimate of water quality, Piper, Ghibbs, Schoeller and Wilcox diagrams, Sodium Absorption Ratio, Color-Alkalinity and Saturation Index studied. Based on the analytical results, groundwater quality in the Hastijan area is generally varies from hard to very hard. The type and facies of water in study area is calcic bicarbonate and sodic and magnesic bicarbonate. In these waters, Ca2+ and Mg2+ concentrations is higher than Na+ and K+, and HCO3- is higher than SO42- and Cl-. Consideration of rocks composition in part of the study area shows that evaporation formation (limestone, Dolomite, Brown Sand Stone, marl, shale and intercalated with gypsum and salt) caused increased Na+, Cl- concentrations and salinity of the groundwater. The results of calculated saturation index show that the saturation index for carbonate minerals is positive and for sulfate minerals is negative. According to the parameters and international standards, almost all of groundwater in the study area is suitable and usable for agricultural purposes and to be used for drinking as good, acceptable water. Finally, the large portion of samples was corrosive for industrial usage.

Nowadays, the use of zonation maps such as ground type zonation, geotechnical parameters, seismic hazard intensity as well as landslides zonation maps have been deployed. These maps are prepared with regard to special purposes and are based on widespread data banks and existing standards. Using these maps, projects costs can be decreased and decision making speed in engineering judgments will increase. In this paper, a new empirical relation is recommended between dynamic probing tests results and shear wave velocity using geotechnical data and dynamic probing tests data related to different sites and the results of down hole tests in 10 different locations in Qom plateau.

The analysis of distribution and characteristics of landslides triggered by earthquakes is important to understand the areas may be susceptible to landsliding in the next earthquakes. One of the most significant effects of the Manjil earthquake (M=7/7, 20/6/1990) was triggering landslides over an extensive area. In this study; the factors of these landslides such as slope, slope aspect, elevation, lithological unites and Arias intensity were investigated using GIS in an area close to the earthquake epicenter. In the next step, two indices called Susceptibility Index (SI) and Frequency Index (FI) presented to predict the location of future earthquake-induced landslides. Finally, landslides susceptibility in the study area has been rated based on these indices. The output of thisstudy can be used to predict landslide susceptible areas in the future earthquakes and to distinguish hazard zones in the overall study area.