مجله زمین شناسی مهندسی
سال ششم شماره 1 (بهار و تابستان 1391)

Determination of uniaxial compressive strength (UCS) of intact rock is an important mechanical parameter required for many engineering projects. In some engineering projects for example well drilling for production petroleum because of more deep well exist limitation for obtain rock core sample and determination UCS. On the other hand determination this parameter is essential in order to analysis well wall stability and wells development program. Because of this, the idea of using drilling cuttings is proposed for determination UCS. In this paper in order to develop relationship between UCS and single compressive strength (SCS) were used from 7 block sample microcrystalline limestone from Asmari formation outcrops. Then UCS test was performed and was determined uniaxial compressive strength. Next these samples were crushed and were prepared 420 single particles. Then SCS for each particle is determined. Since shape of particles effect on particle strength therefore shape of particles has been modified and total particles that used for determination SCS was spherical. In order to study effect size of particle, particles with diameters 2, 3 and 4 millimeter is prepared and determined SCS for each particles. With increase diameter of particle, increase SCS. In order to eliminate effect of size particles is defined variable size and strength and is proposed chart between them. Coefficient of correlation between SCS and UCS is more than 0.91 that present exist good correlation between them.

In this paper reasons of land subsidence in Andisheh street area in Northwest of Mashad city are investigated. The subsidence in this area began simultaneous with the using of constructed building in 2008. This phenomenon results to 1.5 meter ground subsidence and 4 residential building completely destroyed and 15 other buildings became out of service. Aerial photograph indicate that this area is a part of Chelbazeh Fan and the streams of area were used for depot of demolition wastes in the past. For evaluation of thickness and properties of man-made soils in this area 46 handy borehole excavated and electrical resistivity are measured in 9 points. Finally the isothickness map of man-made soil is produced based on the results of Geotechnical and geoelectrical studies. The results of insitu tests showed that clear difference between the density of man-made and natural soil. The average density of man-made and insitu soil were 1.55 g/cm3 and more than 1.8 g/cm3, respectively. The compressibility tests show that the man-made soil are high potential of compressibility and there is a inverse linear relationship between settlement percentage and soil density.

Salman Farsi is located in 180 kilometers of the southeast of Shiraz on the Ghareh-Agai River with the arch-gravity concrete dam of 125m height from the foundation. The grout curtain is situated entirely within the karstic limestone environment in the Asmari formation. To evaluate the quality of the curtain after grouting operation, some boreholes were drilled and water pressure tests were performed on them. In this research, according to the results of water pressure tests on the controlled boreholes, the secondary permeability index was calculated and through the classification of the rock masses, their quality were determined after the grouting operation. Results indicate that although the right bank of grout curtain has better quality than the left bank, however the quality of the grout curtain has been in the range of good to excellent.

Slake durability of rock is an important engineering parameter for evaluating deterioration rock in chemical and physical agents that related to mechanical properties rock. The main purpose of this study is to assess the influence of the number of drying and wetting cycles under variable pH conditions and controls of mineralogical composition on durability. For this purpose, five different types of tuff were selected from different parts in north Qazvin city. The samples were subjected to multiple-cycle slake durability testing with different pH values solution. Also the slake durability tests in saturated condition on samples, petrographical analyses and basic physical - mechanical test were performed. In addition, to assess the influence of mineralogical composition on durability, the mineral contents of the original material and the material passing from the drum of the slake durability apparatus after fifteen cycles were also determined by XRD analyses. It was concluded that the slake durability of tuff is independent of the pH in acidic solution circumstances. Mineralogical composition, fabric and weathering rate are considered to have a greater influence on the slake durability of tuff. A strong relationship between the point load strength and the fifteenth-cycle slake durability index is found in the rock types studied.

Prediction of location of future earthquakes with event probability is useful in reduction of earthquake hazard. Determination of predicted locations has been caused more attention to design, seismic rehabilitation and reliability of structures in these sites. Many theories were proposed in the prediction of occurred time of earthquake. There is not a trusty method for prediction of occurred time of future earthquakes. Many studies have been done in the prediction of magnitude of earthquakes, but there is not any investigation on prediction of earthquake hazard zonation. In this study, the locations that have probability of the event of future earthquake have been predicted by artificial neural networks in Qum and Semnan. Neural networks used in this study can extract to complicate properties of patterns by receipting the interval patterns. Furthermore, the map of earthquake hazard zonation has been drawn. Properties of occurred earthquake were collected since 1903. The most probable event of earthquake in Qum has been predicted 31.6% in center, and 28.9% in north of Semnan.

One of the Catchment Areas has its own parameters according in infiltration to its continent and soil (soil structure, vegetation complex, pore space). In this research, the shores of eternal rivers of Boshehr studied (Mond River – Dashti Township and Bahoosh River – Tangestan Township). In this research, with special lattice and digging 120 well, the infiltration of water to soil measured by double ring outdoor test method and by three repetitions to control and determining the equation and computing equations coefficient of infiltration. By computing soft wares, the rate of infiltration and aggregation infiltration curves depicted and the equations appointed. The computer programs in visual basic language is written in order to determine the equation coefficients that showed the lowest and the minimum standard error (S2) toward the given curves, for Kostiakov and Philip and SCS models. In this research best coefficient of these models with minimal errors for case studied Catchment Area was chosen. Those programs best coefficients of these experiment-adjusted models with arising errors; According to conclusions; SCS in compare Philip and kostiakov has less error in bahoosh Catchment Area. philip models is near to mond Catchment Area in compare kostiakov and SCS models.