Ranking the rock slope instability potential using the Interaction Matrix (IM) technique; a case study in Iran

All the conventional techniques for the analysis of slope stability ranging from simple kinematic analysis using stereonets, to the various widely used limit equilibrium methods, to sophisticated numerical methods belong to a category that are generally known as the analytic approaches and thus are only able to consider a limited number of affecting factors and then solve the problem in details. In contrast, the systems approaches not only can examine the problem in its totality with a complete list of the components, but also can take the interactions between the factors into account. This paper presents a complete application of a well-known systems technique named the Interaction Matrix (IM) in ranking the instability potential of rock slopes of the Khosh-Yeylagh Main Road, Iran as the case study of the research. For this purpose, 15 stations have been selected and a relatively comprehensive database containing the fieldwork information has been constructed. Following the IM technique, the most important factors relating to the general environment and to the rock mass characteristics have been considered. Their reciprocal causes and effects have been analyzed in order to weight each parameter according to its degree of interactivity in the system. Then, the slope instability index has been calculated which refers to the inherent potential instability of each slope of the examined region. The final instability ranking has been presented for the investigated slopes in Khosh-Yeylagh Main Road based on a simple classification. The main aim of the study is to extend the use of systems approach and specifically the IM technique in slope stability analysis. Also, this research shows the importance of consideration of an approximately complete set of key parameters affecting the stability of rock slopes.     

Geodetic constraints on the period of episodic tremors and slips using least squares harmonic estimation method with application to Cascadia subduction zone

It is expected that episodic tremors and slips (ETS) as a type of slow earthquakes with periodic property will be detected using harmonic estimation techniques. The principal goal of this paper is the detection of these kinds of earthquakes using least squares harmonic estimation (LSHE). To accomplish this, the raw time series of 38 permanent GPS stations of the Pacific Northwest Geodetic Array have been analyzed. Previously, some independent techniques could confirm the occurrences of the aforementioned quakes at these stations. However, the current research intends to evaluate the spectrum of each of the de-trended time series using the LS-HE method. In each station, the period of the detected harmonic with the maximum power spectrum is equivalent to the average period previously reported for these events. According to the obtained results, the recurrence interval of these events ranges from 9 months to 3 years. In sum, the study confirms this method being efficient for investigating the occurrences of ETSs when the length of the GPS time series is sufficiently large.     

Calcareous nannofossil biostratigraphy of the Paleocene at the Misheiti section,East Central Sinai,Egypt

Integration of calcareous nannofossil data, δ¹³C and δ¹⁸O values, and carbonate contents of the lower Paleocene–upper Paleocene sequence that crops out at the Misheiti section, East Central Sinai, Egypt, were used to denote the Danian/Selandian (D/S) and Selandian/Thanetian (S/T) stage boundaries. The study interval belongs to the Dakhla and Tarawan formations. Four calcareous nannofossil zones (NP4, NP5, NP6, and NP7/8) were recognized. The base of the Selandian Stage is tentatively placed at the lowest occurrences (LOs) of taxa ascribable to the second radiation of fasciculiths (i.e., Lithoptychius janii). This level is marked by a sudden drop of δ¹³C and δ¹⁸O values and carbonate content. No distinctive lithological changes were observed across the D/S boundary at the study section. A hiatus at the NP5/NP6 zonal boundary is indicated by the condensation of zones NP5 and NP6.The base of the Thanetian is placed at the base of Zone NP7/8 at the lithological change observed in correspondence to the boundary between the Dakhla and Tarawan formations. The δ¹³C and δ¹⁸O values abruptly decrease slightly above the base of Zone NP7/8. No consistent variations in the carbonate contents were recorded within Zone NP6 or across the NP6/NP7/8 zonal boundary.     

Scour and flow field around a spur dike in a 90° bend

Spur dike is an important element in fiver training that creates rapid variations in flow field, sediment transport and bed topography. The mechanism of flow and sediment transport in a channel bend is very complex, especially when a spur dike is constructed in a bend. Most of previous investigations on flow behavior and scour around spur dike were carried out in straight channels. In this paper results of experiments on flow field and scour around a spur dike in a 90 degree channel bend are presented, Sand with uniform grain size was used as the bed material, Experiments were conducted for different locations and different lengths of spur dikes at the bend with different values of discharge, The three dimensional flow fields around a spur dike were investigated, The maximum depth of scour was correlated to the Froude numbers, lengths and the locations of spur dike in the bend.     

Analytical‐numerical solution for stress distribution around tunnel reinforced by radial fully grouted rockbolts

This paper presents an analytical‐numerical approach to obtain the distribution of stresses and deformations around a reinforced tunnel. The increase in the radial stress of the reinforced tunnel, based on the performance of a bolt, is modeled by a function, which its maximum value is in the vicinity of the bolt periphery and it exponentially decreases in the far distance from the bolt. On the basis of this approach, the shear stiffness between the bolt and the rock mass and the shear stress distribution around the bolt within the rock mass are also analytically obtained. The results are compared with those obtained by the assumption of ‘uniform increase of radial stress’ method, which is made by the previous studies. The analyses show when the bolts' spacing is large, the safety factor must be increased if the ‘uniform increase of radial stress’ method is used for the design. Finally, a procedure is introduced to calculate the non‐equal deformation of the rock mass between the bolts at any radius that can be useful to compute the bending moment in shotcrete layer in New Austrian Tunnelling Method (NATM) approach. Copyright © 2016 John Wiley & Sons, Ltd.     

Skill Assessment of Copernicus Climate Change Service Seasonal Ensemble Precipitation Forecasts over Iran

Medium to long-term precipitation forecasting plays a pivotal role in water resource management and development of warning systems.Recently,the Copernicus Climate Change Service(C3S)database has been releasing monthly forecasts for lead times of up to three months for public use.This study evaluated the ensemble forecasts of three C3S models over the period 1993-2017 in Iran’s eight classified precipitation clusters for one-to three-month lead times.Probabilistic and non-probabilistic criteria were used for evaluation.Furthermore,the skill of selected models was analyzed in dry and wet periods in different precipitation clusters.The results indicated that the models performed best in western precipitation clusters,while in the northern humid cluster the models had negative skill scores.All models were better at forecasting upper-tercile events in dry seasons and lower-tercile events in wet seasons.Moreover,with increasing lead time,the forecast skill of the models worsened.In terms of forecasting in dry and wet years,the forecasts of the models were generally close to observations,albeit they underestimated several severe dry periods and overestimated a few wet periods.Moreover,the multi-model forecasts generated via multivariate regression of the forecasts of the three models yielded better results compared with those of individual models.In general,the ECMWF and UKMO models were found to be appropriate for one-month-ahead precipitation forecasting in most clusters of Iran.For the clusters considered in Iran and for the long-range system versions considered,the Météo France model had lower skill than the other models.