By drilling borehole in the ground, the distribution of stress around it changes and stress concentration is created. If the shear stresses induced by in-situ stresses is more than rock strength, it causes a kind of failure around the borehole, which is called breakout. It has been observed that breakout failure zones are initiated and propagated in the direction of minimum in-situ stress. In this paper, by assumption of elasticit behavior of rock mass, the analytical 2D analysis of breakout failure using the Mohr-Coulomb and Hoek-Brown failure criteria is addressed and the failure zone is obtained by using these two criteria. According to the results of the mathematical model, the effective parameters in the depth and width of the breakout occurring around the borehole are depended on the mechanical properties of the materials in the medium as well as the amount and ratio of in-situ stresses. If the ratio of stresses is one, breakout failure will not occur. Also, with increasing the rock quality, the breakout depth decreases, and with decreasing rock strength and increasing the amount and ratio of stresses, the breakout area becomes larger.

In open-pit mine, safety of internal dumps is a significant pointer on the economic perspective of the overall project. It has been found in several studies that unplanned and random deposition of the overburdened material is the main reason for mishaps and failure. The study utilized unmanned aerial vehicles (UAVs) to map the mine dumps, and the precise 3D geometry of the same was reconstructed to evaluate the safety using numerical methods. A framework is proposed to assess and identify the potential zone of instability in the mine dumps. The study was conducted at the open-pit mine at the Raniganj coalfield of Paschim Bardhaman in West Bengal, India. The study assessed the internal dump safety using a 3D limit equilibrium method and numerical methods. Finally, optimum parameters are suggested for the mine dumps geometry under the prevailing geo-mining conditions of the mine site. The framework proposed here for assessing critical zones in mine dumps is cost-effective, easy to use, quick, and efficient.

Introduction: In Iran, being inspired by advanced countries and old patterns of Iranian city pedestrian spaces, the creation of pedestrian zones in the metropolises of the country has become popular to shift from car-oriented to walkability. The creation of the pedestrian zones in Tehran city after a number of relatively successful experiments, such as the 15th Khordad pedestrian zone and Sepahsalar pedestrian zone was followed by the creation of the 17th Shahrivar pedestrian zone. But, the 17th Shahrivar pedestrian zone based on the evidences such as the findings of scholars, criticisms of authorities and the discontent of the local people, is a rather unsuccessful experience. Research objective: This research with an analytical and profound look tries to methodically explain the main failure components of the 17th Shahrivar pedestrian zone in Tehran. Research method: For this purpose, the qualitative approach and the basic tools for collecting information including documents, semi-structured interviews and field observations have been used. The textual data collected mainly by coding, counting and creating the thematic network and the place data mainly by counting, photographing and mapping organized and conceptualized. In this stage, authors have inferred the main causes of project failure with scrutinizing all findings, examining the relationship between the main themes with each other, considering the theoretical foundations of the research and relying on rational and logical arguments. Conclusion: The findings of the article show that the main issues of the project failure are the three main problems: “ The lack of proper need assessment, feasibility study and providing infrastructure for the project” , “ Marginalizing local people in the process of planning and implementation” and “ Macro economic, political and managerial issues” . Meanwhile, the main factor behind the defects and problems of the project seems to be political, managerial, and economic conditions and objectives. The experience of the 17th Shahrivar pedestrian zone indicates that the potential positive impacts of pedestrian zone creation on improving the quality of the environment are only possible if they are correctly located and have a sustainable and grassroots planning and management approach.

Actually, after drilling a borehole, some materials would be eliminated from the original rock mass. The exhumed materials no longer can carry the stresses transferred to the rock surrounding the borehole. The process represents a stress concentration in the rock around the borehole. The so-called borehole breakout failure results from an enhancement in shear stress on the borehole wall because of the excavation-induced increase of the hoop stress surrounding the wall. Vertical borehole breakouts generated via un-equal horizontal in-situ stresses are usually focused in two opposed areas along the least horizontal in-situ stress. Excavation cause loss of balance stresses around the borehole and also cause compressive stress concentration on the walls. Changes in stresses around the borehole may cause formation damage. This status results in other modes of borehole instability such as collapsing of the wall due to shearing failure. Breakout phenomenon (collapsed walls under shear failure) will occur by increased shear stress at the borehole wall which by itself is due to an increase in hoop stress on the wall. Effective stress at any point on the wall or near the borehole is expressed by three main components. These three components include the radial stress component that acts in the direction of the borehole radius, the hoop stress component that is applied to the environment around the borehole, and the axial stress component parallel to the borehole axis. The borehole breakout occurs when the tangential stress and the radial stress are maximum and minimum in the borehole wall, respectively. The borehole breakout will cause the symmetrical stretch of borehole perpendicular to the borehole axis. This phenomenon will also occur in the direction of minimum in-situ stress (, h). In this paper, the goal is to compare four failure criteria including, Mohr-Coulomb, Hoek-Brown, Griffith and Fairhurst to estimate the depth and angular width of the borehole wall in damaged zone, where the stresses are heterogeneous. The results show that damaged zone, undamaged zone and boundary curve of failure around the borehole, can be obtained using the function of failure criteria (F) in σ, 1-σ, 3 plane. The more that the area under the curves of these criteria would be in σ, 1-σ, 3 plane, the less damaged zone will occur around the borehole. For instance, the area under the curve for Griffith criteria in σ, 1-σ, 3 plane, is less than the area of other criteria. So damaged area in Griffith criteria is more than 3 other criteria. Angular width obtained from Hoek-Brown criterion, Mohr-Coulomb criterion and Fairhrust criterion (unlike Griffith) coincide, because these 3 criteria cut the σ, 1 axis with the same width in σ, 1-σ, 3 plane. Also, with the constant value for difference of in-situ stresses (σ, d=σ, H-σ, h), depth of the failure in minimum in-situ stress direction is more in Griffith and Fairhrust criteria in compare with 2 other criteria. By comparing the failure criteria, it has been observed that, with an increase in in-situ stresses ratio (σ, H/σ, h), the results of Griffith and Fairhrust criteria are more close to experimental results in compare with 2 other criteria (Hoek-Brown and Mohr-Coulomb).

In order to study biozones of the Pabdeh Formation in the Northeast Kazerun, Murdak section was selected. In this section, Pabdeh Formation is mainly consists of marl, shale and marly limestone. The study of calcareous nannofossils led to the recognition of 70 species and 28 genera. According to the first and last occurrence of index species and assemblages fossil, the following biozones based on global standard zonations are identified: Discoaster multiradiatus Zone (NP9/ CNP11), Tribrachiatus contortus Zone (NP10/ CNE1-CNE2), Discoaster binodosus Zone (NP11/ CNE3), Tribrachiatus orthostylus Zone (NP12/ CNE4), Discoaster lodoensis Zone (NP13/ CNE5), Discoaster sunlodoensis Zone (NP14/ CNE6-CNE8), Nannotetrina fulgens Zone (NP15/ CNE9-CNE11), Discoaster tanii nodifer Zone (NP16/ CNE12-CNE15), Discoaster saipanensis Zone (NP17/ CNE15-CNE16), Chiasmolithus oamaruensis Zone (NP18/ CNE17-CNE18), Isthmolithus recurvus Zone (NP19/ CNE18-CNE19), Sphenolithus pseudoradians Zone (NP20/ CNE20), Ericsonia Subdisticha Zone (NP21/ CNE21-CNO1), Helicosphaera reticulate Zone (NP22/ CNO2), Sphenolithus predistintus Zone (NP23/ CNO3-CNO4). As a result of this study and based on the obtained biozones, the age of Pabdeh Formation in Murdak section, is Late Paleocene (Thanetian) to Oligocene (Rupelian-Chatian).

Determination of the borehole and fracture initiation positions is the main aim of a borehole stability analysis. A wellbore trajectory optimization with the help of the mud pressure may be unreasonable since the mud pressure can only reflect the degree of difficulty for the initial damage to occur at the wellbore rather than the extent of the wellbore damage. In this work, we investigate the failure extension in different arbitrary inclination boreholes under different in-situ stress regimes. Assuming the plane strain condition, the Mohr-Coulomb, Mogi-Coulomb, and Modified Lade rock failure criteria are utilized. We present an analytical equation to determine the optimum drilling trajectory of an Iranian oilfield. In order to predict the degree of wellbore damage, the initial shear failure location, failure width, and failure depth of arbitrary wellbores are determined. Then a new model is derived to calculate the initial failure area of a directional wellbore because it is more efficient in a wellbore stability analysis. The results obtained show that in the target oilfield, the vertical and low-deviated direction is the optimum drilling path. According to the results of this work, optimization of the wellbore trajectory based on the estimated failure zone is a reasonable method if a considerable failure zone takes place around the borehole wall.

Background and Objective: Degeneration of neurons in the central nervous system occurs during aging. Transplantation of neural stem cells (NSCs) can be preventing the degeneration of neurons. In addition to neuronal replacement, with the production of neurotrophic factors, increased survival and proliferation of endogenous cells. This study was done to compare the cell proliferation, neurotrophic factors expression and features of NSCs harvested from different areas of the central nervous system in vitro.Materials and Methods: In this laboratory study NSCs have been harvested from subgranular zone (SGZ), subventricular zone (SVZ) and central canal of spinal cord from adult Wistar rats with mechanical, enzymatical digestion and subsequently was cultured in α-MEM medium supplemented with serum as monolayer or adherent conditions and passaged for 13 times. Immunocytochemistry was used to determine expression of the nestin and GFAP markers. Semi-quantitative RT–PCR was used to confirm genes expression (NGF, CNTF, NT3, NT4.5, GDNF and BDNF).Results: Morphological features of stem cells extracted from different regions of the central nervous system were similar in the culture. Doubling time NSCs in the SVZ (37.45 hr) is shorter than in the SGZ (44.04 hr) and central canal of spinal cord (57.22 hr). The culture conditions as well as monolayer neural stem cells are capable of producing neurospheres. Also, nestin and GFAP markers, expressed by NSCs. Neurotrophic gene expression pattern profiles were similar to each other in stem cells extracted from the SGZ, SVZ and central canal of spinal cord.Conclusion: Neurotrophic gene expression in stem cells extracted from different regions of the central nervous system were similar, but proliferation capacity was higher in NSCs, which have been harvested from the SVZ.

Due to high strength and stiffness in comparison with their weights, laminated composite materials are widely used in many structures such as aerospace and naval structures. Therefore, the understanding of their failure mechanisms to predict their mechanical response is of high importance. One of the major aforementioned mechanisms is the delamination which commonly occurs in skin/stiffener joints. In the present paper, a comparative study on the delamination in composite skin/stringer structures under 3 point and 4 point bending loads is performed by the finite element method (FEM) employing the cohesive elements. The detailed effects of stacking sequence on the damage of structure are investigated. A user defined interface element has been implemented in the Ansys software in continuum damage mechanics framework based on the bilinear cohesive zone model. The advantage of this method is the modeling of delamination growth without any requirements to the presence of initial crack and remeshing. Comparison of the obtained results from FEM with that of experiment justifies the capability of the employed model to predict the delamination initiation and propagation. The results indicate that in the 3 point bending load, the damage initiates from the adhesive between skin and stringer, while in 4 point bending load it initiates from the interface elements between skin layers near the adhesive bond. Finally, in order to increase the strength of skin/stringer structures, the results strongly recommend preventing the use of 45 and 90 degrees plies near each other around the adhesive bond.