Journal of Engineering Geology

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In this paper, using Mononobe & Okabe method, seismic force and its effects on thin masonry retaining wall inside structural frame (Masonry retaining infill) are presented. In this method, retaining wall has been assumed to be rigid and the prevailing failure mode is sliding of wall bed joint or wall rotation around its toe, whereas the prevailing failure mode of masonry retaining infill is usually flexural cracking in middle zone of wall under out of plane seismic force. In this case, the seismic force distribution is important. Accordingly in this paper, a distribution for seismic forces on masonry retaining infill has been proposed. Also with regard to out of plane behavior of masonry retaining infill in terms of strength and acceptance criteria aspect, failure in body of wall due to out of plane loads has been analyzed. Then, the desired seismic rehabilitation method in case of vulnerable masonry retaining infills has been presented and as a practical example, results of the proposed method with the results of numerical software have been controlled. Finally, according to various conditions predicted for masonry retaining infills, Seismic Retrofit solutions are presented for practical applications.

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Hoek and Brown suggested a method to estimate the strength and deformation modulus parameters of rock masses. The method was then widely used in rock engineering designs. In such designs, the mean values of Hoek and Brown parameters are often used which are not proper values due to the variability of rock mass properties within a great range of values. In such cases, probability analysis of rock mass properties is highly important. The geological strength index is one of the most important parameters in Hoek and Brown equations. Determination of this parameter includes greater uncertainties than determining other parameters. In this paper, based on the results of rock mechanical tests carried out on rock samples of Gol-Gohar iron ore mine, and the required field surveys, the sensitivity of rock mass geomechanical properties on the type of the statistical distribution function of the geological strength index in statistical analysis of these parameters using Monte Carlo simulation method was investigated. The results showed that the sensitivity of Hoek and Brown equations to determine different rock mass geomechanical parameters varies as the type of the statistical distribution function of the geological strength index changes. The sensitivity of geomechanical parameters such as internal friction angle, cohesion, total strength and rock mass modulus on the type of the statistical distribution function of the geological strength index is much less than parameters such as uniaxial compressive strength and tension strength of rock mass. The greatest variations based on changes of the type of the statistical distribution function of the geological strength index are less than 5% for the internal friction angle, cohesion and total strength, less than 10% for the modulus, and less than 25% for the uniaxial compressive strength and tension strength.

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Introduction
Shallow tunnels have a vital role in urban planning, railway and highway transportation lines. The presence of underground cavities can leads to stress concentration and consequently, instability of the spaces against static and especially dynamic loads. Therefore, the aim of this study was to evaluate the effect of elliptical cavity and its inclination on sandstone rock behavior under compressive static and tensile dynamic loads. In order to evaluate the effect of the cavity under static stress conditions, two groups of intact and hole-bearing sandstone cores with 0, 30, 60, and 90 degrees of hole inclination were prepared and tested under uniaxial compressive loading test. During the test, in addition to the stress recording, damage and deformability of the samples were recorded by using the strain gauge, acoustic emission sensor and camera. Split Hopkinson pressure bar (SHPB) test apparatus was used for doing dynamic loading test. Furthermore, the damage process was recorded using a high-speed camera with 10 micro-seconds interval of frame capability. The obtained results showed that presence of the cavity reduced the rock strength in maximum state (θ=0) up to 55% and in minimum state (θ=90) up to 77% of its initial uniaxial compressive strength. Dynamic tensile loading tests illustrate that the elliptical hole near the free end of sample (reflection boundary of compressive wave to tensile wave) is stable due to locating in superposition area, while the other cavity out of the area with each inclination was undergone to spalling failure. Assessment of failure surface using scanning electron microscope and thin section study indicates that the dominant fracture is grain-boundary type and iron oxide cement has a vital role in developing of this type of fracture.