I‌N‌V‌E‌S‌T‌I‌G‌A‌T‌I‌O‌N O‌F A‌R‌E‌A‌S A‌F‌F‌E‌C‌T‌E‌D B‌Y V‌E‌R‌T‌I‌C‌A‌L C‌O‌N‌C‌A‌V‌E C‌O‌R‌N‌E‌R‌S D‌U‌R‌I‌N‌G V‌E‌R‌Y D‌E‌E‌P E‌X‌C‌A‌V‌A‌T‌I‌O‌N‌S A‌N‌D D‌E‌T‌E‌R‌M‌I‌N‌A‌T‌I‌O‌N O‌F T‌H‌E P‌L‌A‌I‌N S‌T‌R‌A‌I‌N R‌A‌T‌I‌O

The mechanism of deformation in very deep excavation is more complex than in shallow excavations. The deformation of the excavation near the corners is lower and a three-dimensional effect can be considered in the design in order to optimize very deep excavations. On the other hand, in practical projects, three-dimensional modeling is avoided and the plain strain models ordinary has been used which will increase the project costs. It must also be ensured that the assumption of a plain strain governs the problem. This study examines the results of monitoring a very deep excavation to a depth of 60 meters which has been stabilized by the anchorage method, validates a three-dimensional model, and considers the vertical concave corner effect in three-dimensional models including factors such as the depth and length of the excavation. Also, the Plain Strain Ratio (PSR) in this excavation is evaluated in accordance with parametric studies. The lowest value of the PSR occurred at a distance of 5 m from the corner and was equal to 0.45. By maintaining the maximum deformation, the length of the anchors was designed first without considering the three-dimensional effect; in another case, the effect of the corners was considered and the volumes were compared. The results showed that if the corner effect was included in the design of the stabilization method, about 21% to 55% of the total length of the anchors would be saved, being dependent on the excavation depth. The minimum and maximum values of the plain strain ratio in the corner and middle of the excavation are the same in all dimensions and are equal to 0.75 to 1. Due to the equality of the dimensions of the excavation (length and height), none of them has an effect on the range of the plain strain ratio values

Numerical Simulation of Tortuosity Effect on the Montmorillonite Permeability

AbstractThis study analyzed the association between the coefficient of permeability of clayey sealing materials and their tortuosity. Montmorillonite was selected because it is used as a barrier in geo-environmental projects and its sensitive structure results in wide variations in permeability when in contact with pore fluids. A DEM code was developed by considering mechanical force, diffuse double layer repulsion, and Van der Waals attraction as the inter-particle interaction. The coefficient of permeability was calculated by simulating a consolidation test and the DEM simulations were compared with experimental data. The results showed that the coefficient of permeability decreased as the void ratio decreased. At the same void ratio, there was a deviation between the coefficient of permeability for clay-electrolyte systems caused by the micro-fabric and variations in tortuosity. Micro-fabric evolution during loading showed that increasing the stress state caused reorientation of the particles perpendicular to the direction of loading and increased anisotropy of the particle orientation, increasing the tortuous flow path

Data for: Effect of initial water content of clay on performance of jet grouting

The used monitored data and some photosTHIS DATASET IS ARCHIVED AT DANS/EASY, BUT NOT ACCESSIBLE HERE. TO VIEW A LIST OF FILES AND ACCESS THE FILES IN THIS DATASET CLICK ON THE DOI-LINK ABOV

Opportunistic scheduling in large-scale wireless networks

In this paper, we consider a distributed one-hop wireless network with n pairs of transmitters and receivers. It is assumed that each transmitter/receiver node is only connected to k receiver/transmitter nodes which are defined as neighboring nodes. The channel between the neighboring nodes is assumed to be Rayleigh fading. The objective is to find the maximum achievable sum-rate of the network in the asymptotic case of n, k à ¿ à ¿. It is shown that the asymptotic throughput of the system scales as n log k/k. An opportunistic on-off scheduling is proposed and shown to be asymptotically throughput optimal.Natural Sciences and Engineering Research Council of CanadaNational Science Foundation (U.S.) (ITR grant CCR-0325401)United States. Army Research Office. Multidisciplinary University Research Initiative (Grant W911NF-08-1-0238

Numerical Study On The Effect Of Geometrical Properties Of Geocell On The Bearing Capacity Of Shallow Foundation Resting On Saturated Marl

Shallow foundation construction on soft and loose soils results in unacceptable deformation, high strain, and failure. Therefore, the implementation of shallow foundation on this type of soil can cause problems in terms of bearing capacity and settlement. Therefore, soil improvement is a logical and appropriate way. Geocell is a series of three-dimensional cells and its main application is to reinforce loose soils. Due to the mechanism of geocell interaction with the soil, the use of geocell reinforcement makes it possible to achieve a greater bearing capacity. In this study, using Abaqus finite element software, the effect of geometrical of geocell on the increase of bearing capacity of shallow foundation resting on saturated marl soil has been investigated. Also, using the analysis of the designed numerical models results, a correlation for homogeneity of the improved soil with geocell reinforcement has been presented instead of considering the soil reinforcement relations. The correlation coefficient and the presented diagram illustrate the high capability of the proposed correlation to estimate the equivalent shear strength to the geocell reinforced soil environment. The analysis results show that by increasing the geocell height for greater than , where S and B are the foundation settlement and the foundation diameter, respectively, the effect of the geocell height on increasing the bearing capacity is noticeable and it is more noticeable in looser soils. Moreover, by increasing the geocell pocket size up to (m) and the geocell length by twice the foundation diameter, there is an increase in the bearing capacity of the foundation and then, there is no noticeable change in the bearing capacity. With an increase in the length of the geocell, it can be stated that the optimal length of the geocell layer is about twice the diameter of the foundation. In order to produce a correlation for estimating the equivalent shear strength of the soil environment reinforced with geocell, a number of numerical models were designed

Relativistic Electron Gun for Atomic Exploration REGAE for Femtosecond Electron Diffraction

The study of dynamics of phase transitions and the breaking of chemical bonds in a reaction is an important and rapidly growing area of modern science. The interest to this topic is gained both by its fundamental aspect and possible applications in fast switching. Some structural changes may occur on a timescale of tens of femtoseconds and the detection of their dynamics requires an advanced measuring technique. The most widely used method for study of the structural dynamics is an all-optic technique, on which the material is excited by a light pulse. The induced structural changes are accompanied by a change in the optical properties of the material that can be measured by second optical probe pulse. Unfortunately, the optical properties of a studied material are not always directly linked to the atomic order and can be influenced by other factors. The direct access to the atomic motion can be obtained by time-resolved x-ray and electron diffraction