JOURNAL OF ENGINEERING GEOLOGY
Year:2017 | Volume:10 | Issue:4 |Papers Count:8

Combination of Adoptive Network based Fuzzy Inference System (ANFIS) and subtractive clustering (SC) has been used for estimation of deformation modulus (Em) and rock mass strength (UCSm) considering depth of measurement. To do this, learning of the ANFIS based subtractive clustering (ANFISBSC) was performed firstly on 125 measurements of 9 variables such as rock mass strength (UCSm), deformation modulus (Em), depth, spacing, persistence, aperture, intact rock strength (UCSi), geomechanical rating (RMR) and elastic modulus (Ei). Then, at second phase, testing the trained ANFISBSC structure has been perfomed on 40 data measurements. Therefore, predictive rock mass models have been developed for 2-6 variables where model complexity influences the estimation accuracy. Results of multivariate simulation of rock mass for estimating UCSm and Em have shown that accuracy of the ANFISBSC method increases coincident with development of model from 2 variables to 6 variables. According to the results, 3-variable model of ANFISBSC method has general estimation of both UCSm and Em corresponding with 20% to 30% error while the results of multivariate analysis are successfully improved by 6-variable model with error of less than 3%. Also, dip of the fitted line on data point of measured and estimated UCSm and Em for 6-variable model approaches about 1 respect to 0. 94 for 3-variable model. Therefore, it can be concluded that 6-variable model of ANFISBSC gives reasonable prediction of UCSm and Em.

Durability is a significant parameter in engineering geology and it shows the extent of the degradability of rocks as the result of mechanical and chemical breakdowns. This phenomenon is closely linked to the composition, porosity and texture of rocks. To understand the relationship between the chemical composition of rocks and their durability the mineralogical properties of the rocks along with durability tests under both acidic and alkaline pH environments were determined. Five samples of limestone and three samples of marl were analyzed. The results revealed that rocks containing high levels of CaCo3 were affected in the acidic conditions while rocks containing high levels of SiO2 were not affected by variance in the pH of the environment. These second groups of rocks were more dependent on the texture of their constituent minerals. Keywords: Slake durability index, pH, Mineralogical properties,

There are various methods for the analysis of the interactional behavior of the surrounding land, using the lining structure which is the most common method of deigning lining structure tools for the static loads by using the hyper static methods. In recent years, there has been a question that depicts whether this method provides the best results in designing the tunnel structure or not. Due to the nonlinear behavior of the earth surrounding the lining structure, utilizing the lining method could lead to conservative results in the design. If it is possible to somehow find the forces caused by the real behavior of the land surrounding the lining structure influencing the structure and conduct the design based on them, more optimal results would be obtained. This study is based on the actual behavior of the land surrounding the lining structure and the displacement of the structure caused by forces with linear behavior in the static design according to the non-linear behavior of the land around the tunnel structure. The behavior is modeled using the non-linear programs and the forces affecting the lining of the structure will be inference. Also there is a case study based on this method in which the soil interaction with the tunnel analysis and designing the lining structure was first performed and eventually the obtained results were compared with the hyper static method. In this paper, analysis of maintenance system with lower thicknesses considering land-shield, indicated that applying the reinforced concrete with 40cm thickness has the potential to tolerate the applied load but lining with 45cm thickness is capable of tolerating the loads of design and it can be concluded that applying the simulation method combined with the soil and structure besides considering the nonlinear behavior of the soil leads to more economical results in a project.

This research focuses on the identification and description of various features of pseudokarst in different parts of Alvand granitic batholith, Hamedan, west of Iran. In the literature, karst features have been presented as specific types of terrains or landscapes with particular characteristics suites of well-known surface and subsurface dissolutional forms. Whereas, pseudokarst refers to non-dissolutional surface or subsurface features and landforms created in different areas such as slopes, coastal lines crushed stone areas, lava tubes and permafrost regions. In this research, a comprehensive field investigation program has been carried out. During the field investigations, the most important features of pseudokarst in Alvand granitic batholith have been recognized and classified. Results show a wide range of pseudokarst features in the Alvand granitic rock masses. These landforms are created by erosion, weathering processes and some holes caused by rock block movements in the rock slopes. Some of the most important forms and features of the pseudokarst in the studied area contain tafoni, genama, pseudokarren, talus caves, caves associated with the residual blocks and erosional forms along joints and fractures within the granitic rock masses.

Consolidated-drained triaxial compression tests were conducted to compare the stress-strain and volume change response of sands and clayey sands reinforced with discrete randomly distributed polypropylene fibers. The influence of various test parameters such as fiber content (0. 0%, 0. 5% and 1. 0% by weight), clay content (0%, 10% and 20% by weight), relative density (50% and 90%) and confining pressure (100 kPa, 200 kPa and 300 kPa) were investigated. It has been observed that addition of clay particles to the sands decreased the shear strength of samples. Also, increase in clay content reduced dilation and increased compressibility of the mixed soil. Addition of the fiber to both sands and clayey sands samples improved the shear strength and increased ductility and axial strain at failure point.

Evaluation of the excavation-induced ground movements is an important design aspect of supporting system in urban areas. This evaluation process is more critical to the old buildings or sensitive structures exist in the excavation-affected zone. Frame distortion and crack generation are predictor of building damage resulted from excavation-induced ground movements, which pose challenges to projects involving deep excavations. Geological and geotechnical conditions of excavation area have significant effects on excavationinduced ground movements. In some cases, excavation area may be located in the jointed or weathered rocks. Under such conditions, the geological properties of supported ground becomes more noticed due to the discontinuities and anisotropic effects. This paper is aimed to study the performance of excavation walls supported by nails in jointed rocks medium. The performance of nailed wall is investigated based on evaluating the excavation-induced ground movements and damage levels of structures in the excavation-affected zone. For this purpose, a set of calibrated 2D finite element models are developed by taking into account the nail-rock-structure interactions, the anisotropic properties of jointed rock, and the staged construction process using ABAQUS software. The results of this paper highlight effects of different parameters such as joint inclinations, anisotropy of rocks and nail inclinations on deformation parameters of excavation wall supported by nails, and induced damage in the structures adjacent to the excavation area. The results show that the relationship between excavation-induced deformation and the level of damage in the adjacent structure.

Free vibration of soil often occurs during earthquakes. Since the vibration caused by earthquake does not have (steady state harmonic vibration) continuity, the alluvium vibrates with its natural frequency between two natural seismic waves. This study evaluates the effect of piles on the period of free vibration of a soil layer using numerical method. In the first stage, using analytical equations for calculation of vibration period of a soil layer and a column with continuous mass, the results were analyzed by the software. In the second step, piles with the same dimensions and distance were added step by step, and the vibration period for the soil layer with piles was calculated. The friction or floating effects of the piles on alluvial soil vibration period was also examined. The results show that as the number of piles increases, the differences between the results of one dimensional analysis of alluvium soil and the results of the software become different, and this creates the need for specific arrangements for seismic analysis of this kind of alluvium (with inserted piles). The results also suggest that end-bearing piles have a greater effect on alluvial soil vibration period, and with increased amount of the floating of these piles, these effects decline.