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The ground control problem of face fall has long been a major concern in mining high-seam single-cut longwall faces in China. The influence of coal fractures and cleats on face stability, however, have not been studied in depth in the previous studies. This paper has analyzed the deterioration of the pre-existing opening-mode fractures on the mechanical and deformation behaviors of the coal mass by performing uniaxial compression tests on the coal-like physical samples with fabricated fractures and the effects of coal cleats on longwall face stability using 3DEC numerical modeling. The results show the following: (1) The fabricated discontinuities in the physical coal-like samples reduce the yield strength and elastic modulus by approximately 20–45%. (2) Strength and modulus of the physical samples increase with the joint spacing but decrease with the joint trace length and connectivity ratio. (3) Face-cleat angle (the right angle between the faceline and the cleat orientation) has a major effect on the face displacement, and longwall face stability can be improved by adjusting the face development direction with relation to the cleat orientation during mine planning for face development. (4) Face displacement decreases with the increase of cleat spacing, but this effect becomes insignificant with the further increase of the cleat spacing.(5) Bedding planes in the coal mass have very little impacts on the face stability. [ABSTRACT FROM AUTHOR]

Copyright of Hydrogeology Journal is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Venus' thick atmosphere is capable of destroying kilometer-sized bodies such as asteroids, creating various types of traces on the surface. While larger cosmic bodies are able to reach the surface, creating impact craters or crater dispersion fields, smaller bodies effectively transfer the initial kinetic energy into the atmosphere, resulting in an "atmospheric explosion" at some altitude. In these cases, the most visible marks on the surface of Venus are created by atmospheric shock waves and the flow of gas behind the shock fronts reflected from the solid surface. The transitional sizes of impactors that break up in the atmosphere but reach the surface give rise to clusters of craters. The paper presents the first results of three-dimensional calculations of the destruction of rocky asteroids in the atmosphere of Venus, indicating significant differences from simple two-dimensional axisymmetric calculations. [ABSTRACT FROM AUTHOR]

Glacier lake outburst floods (GLOFs) initiate with the rapid outburst of a glacier lake, endangering downstream populations, land, and infrastructure. The flow initiates as a mud flow; however, with the entrainment of additional solid material, the flood will often transform into a debris flow. As the run-out slope flattens, the coarse solid material deposits and the flow de-waters. The flow transforms back into a muddy, hyperconcentrated flow of fine sediments in suspension. These flow transitions change the flow composition dramatically and influence both the overall mass balance and flow rheology of the event. In this paper, we apply a two-phase/layer model to simulate flow transitions, solid–fluid phase separations, entrainment, and run-out distances of glacier lake outburst floods. A key feature of the model is the calculation of dilatant actions in the solid–fluid mixture which control flow transitions and phase separations. Given their high initial amount of fluid within the flow, GLOFs are sensitive to slope changes inducing flow transitions, which also implies changes in the flow rheology. The changes in the rheology are computed as a function of the flow composition and do not need any adaptation by ad-hoc selection of friction coefficients. This procedure allows the application of constant rheological input parameters from initiation to run-out. Our goal is to increase the prediction reliability of debris flow modeling. We highlight the problems associated with initial and boundary (entrainment) conditions. We test the new model against the well-known Lake 513 (Peru, 2010), Lake Palcacocha (Peru, 1941), and Lake Uchitel in the Aksay Valley (Kyrgyzstan) GLOF events. We show that flow transition modeling is essential when studying areas that have significant variations in slope. [ABSTRACT FROM AUTHOR]

Coherent structures (CSs), which are the most often understood as time-stable vortices, play an important role in the Earth's climate system, since they make a significant contribution to the processes of momentum and heat and mass transfer of any fluid medium, including the atmosphere and the ocean. This is true for all scales of motion, but is particularly important for more chaotic mesoscale processes. A reliable methodology for identifying mesoscale vortices can potentially stimulate the development of a deterministic climatology of mesoscale processes. The main difficulty in developing this direction is the absence of a rigorously mathematical definition of a vortex, which makes it impossible to automatically search for CSs in spatial data. At the same time, the increase in the spatial resolution of numerical models makes this problem increasingly urgent. Some developments in this direction have been carried out in the field of small-scale turbulence: a number of criteria have been developed that allow for the identification of vortices with varying degrees of reliability. In this paper, the applicability of the three most popular criteria for CS identification in significantly larger-scale geophysical data is studied. [ABSTRACT FROM AUTHOR]

The understanding of the complex soil–pile–raft interaction and their mobilization with the level of settlement is an important aspect for the performance-based design of the combined pile–raft foundation (CPRF). This paper investigates the influence of various interactions governing the load-bearing mechanism of a vertically loaded CPRF using a three-dimensional finite element-based computer program. The soil was modeled using the conventional Mohr–Coulomb elastic-perfectly plastic constitutive relationship and the drained condition was adopted in the analysis. Piles and raft were modeled using embedded beam elements and plate elements respectively. After successful validation of the developed numerical model, extensive numerical simulations were carried out considering a CPRF of different geometries and configurations where the foundation was subjected to incremental settlement boundary conditions. The variation of pile–pile, pile–raft and raft–pile interactions with settlement and their influence in dictating the loads induced within the foundation components were obtained. The analysis results indicated that the settlement levels played an important role in the mobilization of loads and dictating the efficiency of CPRF. Piles within a CPRF were able to mobilize their full capacity at the settlement of 1.5–2% of the raft width. The level of settlement and the spacing between the piles dictated the transition from negative interaction to positive interaction indicating a higher capacity of a CPRF compared to the combined capacities of piles and raft at higher settlement levels. Results suggested the operating settlement of CPRF which may be useful for geotechnical practitioners in making this foundation a cost-effective foundation choice. [ABSTRACT FROM AUTHOR]

China has planned and built several world-class cascade high dams in Jinsha River, Dadu River, Lancang River, and Yarlung Zangbo River. The complex geological conditions in the reservoir area and numerous large-scale landslide bodies make the potential disaster risk of overflowing and cascade dam failure caused by landslide-generated tsunami under increasing severe situations. However, the study on describing and predicting the complex dynamic processes of generation, propagation, overflowing, wave setup, and the interaction between tsunami and lakeshore has not been systematically carried out. Based on the high-order Boussinesq-type equations, the development of the dynamic system of tsunamis in lakes coupled with the landslide process is realized using the finite volume method in this paper. To verify the accuracy and reliability of the study, the Xiluodu Reservoir is selected as the object to simulate the potential landslide-generated tsunamis. The factors such as the generation and propagation of tsunamis, dam overflowing, and wave setup in the downstream river are quantitatively evaluated and analyzed. The constructed landslide with a total volume of 24×106 m3 generates a near-field wave amplitude of about 28 m. The maximum wave run-up height is about 95 m, the volume of the dam overflowing water up to 2.13×106 m3, and the maximum wave height above the dam crest presents an M-shaped distribution. This LGWs event raises the downstream water level by nearly 40 m. The results show that the risk of landslide-generated tsunamis in the reservoir area in China cannot be ignored. The developed Boussinesq-type equations coupled with the landslide dynamics can simulate the whole process of generation, propagation, runup, and estimating the overflowing water volume of the tsunamis in the lake, laying a foundation for the quantitative risk assessment of tsunamis in lakes of high cascade dams in China. [ABSTRACT FROM AUTHOR]

This paper presents an experimental and numerical study of the fatigue-corrosion behavior of the high strength low alloy steel known as HSLA steel in marine environment. Based on a case study of steel removed from of hull ship after about 1300 h of service in seawater, microstructural fatigue-corrosion indicators are detected such as micro-cracks, micro-pits, and beach marks. In addition, the mechanical properties decreased dramatically. Pitting corrosion acts as the main phenomena leading to the metal deterioration. This is confirmed through electromechanical calculation and potentiodynamic curves. Since, the environment is harsh and out of our control, a numerical study of the effect of pitting and the coupling between fatigue and pitting corrosion is held. The results show that the geometry of corrosion defect is responsible for the propagation of the pit and can lead to the crack formation. von Mises stress propagation is controlled too by the corrosion potential distribution. [ABSTRACT FROM AUTHOR]

In this paper, we present the results of numerical model and simulation of water transfers in soils with low water content. The main objective is to identify the major phenomena which allow to adequately describe water transfer in soil between the filtration of liquid phase and the capillary rise. We have shown that in the superficial layer of soil, the ambient atmosphere has less influence on the transfer phenomena at low water content. The bibliographic works realized on water transfer mechanisms do not allow to draw conclusions at very low water contents that is why the present manuscript brings answers to concerns not yet elucidated. The methodological approach is based on the off-center upstream method for the flux convection and the implicit scheme in time for the discretization using the Finite Volumes method. The numerical resolution of the problem is based on the Newton–Raphson method. Water profiles for different sizes of sample (30 cm, 40 cm, 50 cm and 60 cm) and for initial water contents, w0, varying from 2 to 7% were obtained at regular time interval of 85,000 s. All the simulation results highlight two distinct domains for water contents w < 4 and three distinct domains for water contents w ≥ 4%. Indeed the lower limit conditions on the flux of filtration cause an accumulation of water leading to an increase in water contents for initial water contents of 4%, 5%, 6% and 7%. We note the existence of a limiting water content wlim = 2.4% representing the hygroscopic limit of the soil. [ABSTRACT FROM AUTHOR]

This paper studies the self-ignition of hydrogen flowing under pressure into a channel filled with an oxidizer medium containing neutral components, such as water vapor, helium, carbon dioxide, nitrogen, and argon. The work is carried out by the numerical modeling, taking into account the finite time of the rupture of the diaphragm dividing the high-pressure chamber and the channel. The calculations performed show that the ignition delay time of hydrogen increases with the H2O, He, CO2, or N2 concentration and when a certain concentration of the additive is reached, the hydrogen self-ignition does not occur. At the same time, it is demonstrated that self-ignition could develop in the form of two types of ignition kernels, occupying the entire channel cross section or localized near its wall. Furthermore, in some cases, the ignition kernel localized near the wall turns out to be unsteady and quenches before the hydrogen jet exits the channel. When the oxidant is diluted with argon, a qualitatively different scenario of the development of the process is observed, and with an increase in the argon content in the oxidizing medium, the self-ignition time decreases. Moreover, ignition occurs even at a very high content of argon in oxygen of up to 99.5%. This effect is related to the significantly lower heat capacity of argon compared to other neutral additives and, consequently, to the more intense heating of the oxidizing medium due to the hydrogen jet flowing into the channel. [ABSTRACT FROM AUTHOR]

The paper presents the results of numerical simulation of three-dimensional turbulent flow around a hydraulic turbine guide vane at the angle of attack of 9° with the aspect ratio of the foil equal to 0.8. The influence of turbulence modeling variants on 3D flow effects is analyzed. The 3D boundary layer separation at the vane-sidewall junctions and the flow separation near the trailing edge influence the flow pattern. The study considered various approaches for modeling of a turbulent flow, such as the k-ω SST turbulent viscosity model and several variants of the differential and algebraic Reynolds stress models. At the given angle of attack, the k-ω SST model shows a significant separation zone in the corners between the wall and the vane, while no separation of the flow in the central plane is observed. Both differential and algebraic Reynolds stress models reproduce the secondary vortex flow at the corners and suppress the flow separation near the central cross section. [ABSTRACT FROM AUTHOR]

In this introduction we briefly summarize the 14 contributions to Part I of this special issue on Tsunami Science Four Years after the 2004 Indian Ocean Tsunami. These papers are representative of the new tsunami science being conducted since the occurrence of that tragic event. Most of these were presented at the session: Tsunami Generation and Hazard, of the International Union of Geodesy and Geophysics XXIV General Assembly held at Perugia, Italy, in July of 2007. That session included over one hundred presentations on a wide range of topics in tsunami research. The papers grouped into Part I, and introduced here, cover topics directly related to tsunami mitigation such as numerical modelling, hazard assessment and databases. Part II of this special issue, Observations and Data Analysis, will be published in a subsequent volume of Pure and Applied Geophysics. [ABSTRACT FROM AUTHOR]

Large-scale panel destressing is a rockburst control technique that is used to create a stress shadow in the ore pillar to be mined. The technique aims to reduce the pillar burst proneness by deviating the major induced principal stresses away from the concerned zone of interest. The destress panels, situated in the pillar hanging wall, are choke-blasted with high explosive energy density, and the blast-induced damage in the panel is accompanied by stress dissipation and stiffness reduction due to fragmentation in the panel. These two effects are traditionally modeled holistically with stiffness and stress reduction factors α and β, respectively, applied to the destressed zone. This paper focuses on the interpretation of Phase 3 destress blasting results at Copper Cliff Mine (CCM) where a stress increase (rather than decrease) was detected in the ore pillar crown, while a stress decrease was recorded in the ore pillar sill (as expected). It is hypothesized that high mining-induced stress anisotropy in the pillar crown caused blast-induced fractures to propagate in the orientation of the major principal stress, a condition that would hinder the destressing effect in that orientation. To verify the hypothesis, a series of panel anisotropic rock fragmentation and stress dissipation factors are iteratively tested in a 3-dimensional back analysis of the Phase 3 destress blast. The analysis takes into consideration the stope extraction schedule per the mine plan to better replicate the mining-induced stress condition in the panel and the ore pillar. The results show good agreement with stress measurements taken in situ using borehole stress cells installed in the ore pillar prior to destressing. The paper discusses the implications of preferential fracture propagation orientation and how it might affect the efficiency of destress blasting. [ABSTRACT FROM AUTHOR]

The paper studies the particle retention and permeability impairment in porous media. This problem results from the re-injection of produced groundwater during oil production into the oilfields in order to reduce environmental damage. The lattice Boltzmann method (LBM) is used to simulate the fluid flow. The discrete element method (DEM) is adopted to simulate the particle motion. The fluid-solid interactions are simulated using the immersed moving boundary method (IMB). Based on the coupling LBM-DEM-IMB method, the paper studies the effect of particle diameter, flow rate, particle volume fraction and injection amount on the particle retention and permeability impairment. Results indicate that larger particle diameter, lower flow rate, higher volume fraction and more particle injection lead to more severe permeability impairment. In order to further study the effect of particle suspensions on heterogeneous reservoirs, a two-channel model with different permeabilities is established. The simulations show that smaller particles tend to retain in the low permeable channel and its permeability impairment is more severe. On the contrary, larger particles can reduce the permeability of high permeable channel, but they can protect the permeability of low permeable channel due to the mechanism of membrane filtration. Therefore, the sweep efficiency and oil recovery of the heterogeneous reservoirs can be improved by re-injecting produced groundwater after reasonable pretreatment. The re-injection also reduces environmental damage resulting from the large amounts of produced water in petroleum engineering. This paper provides some references for general studies on the flow of particle suspension in porous media. [ABSTRACT FROM AUTHOR]

The assessment of yielding rockbolt performance during rockbursts with actual seismic loading is essential for rockburst supporting designs. In this paper, two types of yielding rockbolts (D-bolt and Roofex) and the fully resin-grouted rebar bolt are modeled via the "rockbolt" element in universal distinct element code (UDEC) after an exact calibration procedure. A two-dimensional (2D) model of a deep tunnel is built to fully evaluate the performance (e.g., capacity of energy-absorption and control of rock damage) of yielding and traditional rockbolts based on the simulated rockbursts. The influence of different rockburst magnitudes is also studied. The results suggest that the D-bolt can effectively control and mitigate rockburst damage during a weak rockburst because of its high strength and deformation capacity. The Roofex is too "soft" or "smooth" to limit the movement of ejected rocks and restrain the large deformation, although it has an excellent deformation capacity. The resin-grouted rebar bolt can maintain a high axial force level during rockbursts but is easy to break during dynamic shocks, which fails to control rapid rock bulking or ejection. Three types of rockbolts cannot control the large deformation and mitigate rockburst damage effectively during violent rockbursts. The rockburst damage severity can be significantly reduced by additional support with cable bolts. This study highlights the effectiveness of numerical modeling methods in assessing the complex performance of yielding rockbolts during rockbursts, which can provide some references to improve and optimize the design of rock supporting in burst-prone grounds. [ABSTRACT FROM AUTHOR]

The Yellow Sea is recognized as a meteotsunami "hot-spot", with a relatively high rate of events' occurrence. The March 2007 and May 2008 meteotsunami events attracted large attention due to their deadly and high impact on the west coast of the Korean Peninsula. However, other small size meteotsunamis remain less known because of their insignificant coastal effect. Yet, a better understanding of meteotsunami hazard in the Yellow Sea can be achieved through investigation of both large and small events. This paper reveals the occurrence of a meteotsunami on 11–12 June 2009 in the eastern Yellow Sea, and addresses the analyses of the sea-level and air-pressure data, the meteotsunami genesis mechanism by the atmospheric forcing, and the numerical modeling of meteotsunami propagation. Analysis results evidence that a moving air-pressure jump of about 3 hPa disturbed the sea surface and induced a meteotsunami with wave height up to 0.45 m (crest-to-trough) which were observed at the Janghang (JH) station. Both meteorological observations and numerical modeling support a speed of 11–13 m/s for the atmospheric disturbance propagation, which is smaller than the optimal condition for Proudman resonance of meteotsunamis in the eastern Yellow Sea. Here, we demonstrate that the Greenspan resurgence was responsible for the tsunami-like waves. This study unravels new insights into the formation, amplification, and hazard extent of small size meteotsunamis in the eastern Yellow Sea. [ABSTRACT FROM AUTHOR]

The main provisions of the phase-field method for concentrated solutions and the problems of numerical modeling of a thermodynamically consistent model of the dynamics of the order parameter for phase transformations of the first kind in the framework of the phase-field approach are briefly considered. The model is based on extended irreversible thermodynamics, which uses Gibbs potentials of real systems to describe the state of the system. Numerical algorithms for modeling phase-field equations for both locally equilibrium and locally nonequilibrium models of relaxation dynamics are derived from the gradient-stability condition, which guarantees a decrease in the free energy of the system during relaxation. The estimates of the eigenvalues of the Hessian matrix in the lattice space allow us to construct a gradient-stable algorithm for modeling the time evolution of the phase-field equations in real thermodynamic systems, despite the existing differences in Gibbs energies. The paper analyzes gradient-stable numerical schemes for stability to small deviations for phase field equations in the Fourier approximation. The numerical calculations performed for the SiAs solution demonstrate the stability of the obtained algorithm both with an increase in the time step by several orders of magnitude, and with an increase in the driving forces due to severe supercooling of the system. [ABSTRACT FROM AUTHOR]

This paper presents the details of an experimental and numerical analysis performed on two 1.0 m and one 0.9 m diameter bored piles socketed in the conglomerate rock mass. The study investigates how shaft and base resistance contribute to load settlement behavior of piles built in poorly and well-cemented conglomerate rock mass. Two of the piles were constructed as complete sockets, and the third one is a shear socket only. The testing procedure included measuring pile cap settlement and deformations along with the pile (telltales and strain gauges). The results indicate that not only well cemented but poorly cemented conglomerate as well can sustain heavy surcharge before settlements indicating the commencement of full slip were reached. Numerical simulation of the socket with explicitly modeled roughness was applied to assess the influence of socket side surface strength on the behavior of the test pile. The parameters of numerical models were derived from back analysis of field pile load test combined with recorded socket side roughness and the strength parameters obtained by the direct shear tests of conglomerate intact specimens. The results were compared with the experimental observations, and a good level of agreement with measurements was confirmed. Highlights: Reports the results of full-scale axially loaded bored piles socketed in a poorly cemented conglomerate rock mass, serving as a benchmark for verifying empirical models for piles of the relevant type. Reports the pile shaft roughness data and intact strength of conglomerate rock samples. Discusses and clarifies the pile-rock mass interaction. Introduces a complex 2D numerical model including shaft roughness, significantly contributing to understanding the pile-rock mass interaction mechanisms. [ABSTRACT FROM AUTHOR]

Conversion of old underground workings into opencast mines leads to rock displacement, collapse of partition, and slope failures some times. Continuous monitoring of slopes and partition is required to maintain the stability over old workings. Wireless sensor network is more suitable method for continuous monitoring, and it is cost-effective, two-way communication, and provides real-time monitoring and analysis of data. In this paper, development of a low-cost Zigbee based Wireless Data Acquisition System (WDAQ) is described. Field investigations were carried out in an opencast coal mine in south India to assess the strain and deformation for different partition thicknesses of 4.12m, 5.91m, 6.86m, 7.91m, 10.21m and 12.10m over old underground workings, due to the external load caused by the movement of Heavy Earth Moving Machinery (HEMM). Maximum strain and deformation were 387 × 10−6 and 2.41 mm for 4.12 m partition, respectively. It can be observed that the strain and deformation are decreased with increased partition thickness. This paper also describes that the validation of data based on Zigbee based WDAQ with conventional method of monitoring as well as numerical modeling. The data obtained using WDAQ is in close to the other two methods. The variation is around 5–19%. [ABSTRACT FROM AUTHOR]

This paper is written mainly as a review of the first results of the implementation in Russia of a new electrotechnological conception of how to construct a plant for vitrifying radioactive waste (RAW) by induction melting in a cold crucible (IMCC). The study considers pilot RAW IMCCR plants and their variants in Russia and abroad with an enhanced capacity and low frequency so as to make the equipment more productive and reliable in operation. Additional steps are proposed and tested for inclusion in the conception to increase the service life of equipment and control systems. [ABSTRACT FROM AUTHOR]

In this paper, both numerical and analytical method were developed for computing, in strip or plate rolling, the distribution of roll pressure, rolling force, and rolling torque (from which also rolling power can be estimated), assuming an homogeneous deformation of the rolled material. Unlike other similar models present in the literature, which solve the resulting rolling differential equation for the roll pressure, the model presented in this work solves the problem for the horizontal force. In this way, it is possible to avoid the calculation of the derivative of material flow stress curve, which is not always analytically easy and possible (i.e., point material flow stress data). The proposed numerical model is based on the friction law proposed by Chen and Kobayashi while the analytical one is based on the simple shear friction model and brings to useful analytical formulas for a quick calculation of rolling torque and force. Moreover, a relationship between the shear friction factor and Coulomb friction coefficient in rolling was found. The developed models show good agreement with experimental measures, in terms of rolling force and torque, found in literature. [ABSTRACT FROM AUTHOR]

Coherent structures (CSs), which are the most often understood as time-stable vortices, play an important role in the Earth's climate system, since they make a significant contribution to the processes of momentum and heat and mass transfer of any fluid medium, including the atmosphere and the ocean. This is true for all scales of motion, but is particularly important for more chaotic mesoscale processes. A reliable methodology for identifying mesoscale vortices can potentially stimulate the development of a deterministic climatology of mesoscale processes. The main difficulty in developing this direction is the absence of a rigorously mathematical definition of a vortex, which makes it impossible to automatically search for CSs in spatial data. At the same time, the increase in the spatial resolution of numerical models makes this problem increasingly urgent. Some developments in this direction have been carried out in the field of small-scale turbulence: a number of criteria have been developed that allow for the identification of vortices with varying degrees of reliability. In this paper, the applicability of the three most popular criteria for CS identification in significantly larger-scale geophysical data is studied. [ABSTRACT FROM AUTHOR]

The paper presents results of a study of middle crustal (amphibolite-facies level) desilicated rocks exemplified by corundum-bearing plagioclasites developing after metabasites at the unique Khitostrov corundum deposit in the Belomorian–Lapland orogen of the Fennoscandian shield, with emphasis placed onto newly acquired geological data, documentation and analysis of the metasomatic zoning, determination of the P–T conditions of its formation, and a model of the metasomatic process. [ABSTRACT FROM AUTHOR]

Copyright of Hydrogeology Journal is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The evaluation of soil-structure response behavior and the development of soil pressures under dynamic loading is critical for the design of closely spaced underground structures. 3D effects, kinematic soil-structure interaction (SSI), and elastic–plastic soil behavior are common limitations to current analytical approaches and 2D numerical models. Results from large-scale shake table tests conducted at E-Defense are used to create and calibrate a 3D FEM model in Abaqus. The complex SSI behavior was validated in terms of depth-dependent soil accelerations and magnitude and distribution of seismic soil pressures along the vertical shaft walls. Parametric studies were executed to assess the influence of soil friction angle, soil cohesion, as well as structural rigidity on the development of seismic soil pressures and wall deformations. Results suggested the soil cohesion to be instrumental on the wall-soil-interaction, and superior in its influence compared to friction angle. The paper presents valuable details and lessons learned from the extensive 3D modeling exercise and provides guidance for numerical replication of shake table experiments, including the simulation of laminar shear rings, contact elements, soil-ring friction, as well as membrane and boundary effects. [ABSTRACT FROM AUTHOR]

Abstract—The formation of supershear rupture (with a slip front propagation velocity higher than S-wave velocity in the material) along a model fault with homogeneous and heterogeneous surface is analyzed based on the results of numerical simulation. Heterogeneity of the properties is specified by friction spots weakening at shear, interspersed with stable friction segments between them. This problem statement goes back to the well-known asperity model (Kanamori and Stewart, 1978). In this paper, we use seismological and geodetic data to estimate characteristic sizes of the fault-zone segments that are locked during interseismic period. Calculations show that the characteristic sizes of inhomogeneities on the slip plane largely determine the pattern of dynamic rupture propagation. A necessary condition for rupture to pass into supershear is a sufficiently rapid frictional weakening. The observed wavefield features (relatively weak attenuation, an increase in the amplitude of oscillations at some distance from the hypocenter, the predominant motion in the direction parallel to the fault, etc.) do not necessarily need nonlinear medium and are not the result of generation of a "shock wave," as assumed in some publications, but are only a result of wavefront interference. Interaction between regions with different frictional properties can cause rupture transition to supershear, induce dynamic slip pulses which re-fracture the fault segments previously displaced by the creep process, and slowdown rupture propagation. Judging by the results of calculations, rupture is more likely to accelerate into supershear on rough/undulating segments of contact surfaces with closely spaced frictional weakening zones. At the same time, propagation of such a rupture with a decaying displacement amplitude can be stable on locally smoother segments. [ABSTRACT FROM AUTHOR]

Laser polishing is a promising surface finishing technique aimed at improving surface quality. Single-line scanning is the premise of the entire surface polishing. This paper developed a three-dimensional transient finite element model which described the distribution of temperature and stress field in the single-laser scanning. Meanwhile, the molten pool width was predicted by the model, and then verified by experiments. The results illustrated that high temperature and significant thermal gradient would occur near the heat source, which easily led to residual stress. The stress components were different, forming anisotropic stress distribution in the part, and the maximum stress component (σx) was along the scanning vector direction. The errors between the predicted values and the experimental values of the molten pool width were mostly less than 10%. The cross-sectional metallographic diagram showed that the typical micro-structure of SLM Ti6Al4V alloy was columnar β crystal and acicular α′ martensite. This provides a basis for optimizing and improving surface laser polishing technology. [ABSTRACT FROM AUTHOR]

This paper presents the results of analysis and numerical modeling of the sedimentary basins of the riftogenic trough of the Tatar Strait, the Sea of Japan, which allowed the creation of its 3D structural model and determination of the conditions for the formation of its generation-accumulation hydrocarbon systems. To study the geodynamic evolution of the sedimentary basins in the Tatar Strait, the digital reconstruction of the history of subsidence and sedimentation was performed using the numerical basin modeling technologies. The chronothermobaric conditions of the occurrence and evolution of the sources of hydrocarbon generation and the formation of oil and gas accumulations in the sedimentary basins of the riftogenic trough were reconstructed by 3D modeling of the generation–accumulation hydrocarbon systems using PetroMod software (Schlumberger, Ltd., United States). Modeling of the hydrocarbon systems revealed the fundamental features of their structure in the Tatar Strait water area at the modern stage of their development, which are generally as follows: the sources of hydrocarbon generation are located in the depressions of the sedimentary basins, the rock maturity decreases from south to north with their occurrence depths, and hydrocarbons accumulate along the marginal zones of the basins. [ABSTRACT FROM AUTHOR]

Numerical modelling development for capillary barrier investigation considering unsaturated soil–geotextile interface has been studied and evaluated in recent years. Most engineering constructions involving geomaterials and geotextiles application, such as reinforced walls, slopes, embankments, and roads, require understanding the hydraulic performance of those systems for design purposes (capillary barrier, drainage, filtration, etc.). Considering that the hydraulic behavior of those materials is directly dependent on their saturated–unsaturated state over time, unsaturated principles should be applied for their long-term evaluation. This paper presents a 1D (one-dimensional) numerical analysis of an unsaturated system composed of soil and gravel layers separated by a geotextile in a column laterally impermeable (2.0 m). A non-woven geotextile was applied considering different soil types from the literature, such as silty sand, sandy, compacted residual silty, bimodal, and compacted residual sandy soils. A SEEP/W finite element numerical model was developed to perform transient analyses through the system to evaluate its hydraulic performance in terms of capillary barrier formation considering different geomaterials combinations in different hydraulic conditions. A significant influence of geotextile hydraulic conductivity and water flow rate were verified on the capillary barrier effect. Also noticed were the different height and duration of capillary barrier formation for different soil profiles. A design chart-table was proposed to evaluate soil–geotextile performance in terms of capillary barrier for new geotechnical designs. Finally, it could be inferred that fine-grained soils demonstrated to develop higher and longer water column (positive pore pressure) compared to coarse-grained soils, independently of their initial suction. [ABSTRACT FROM AUTHOR]

Manufacturing large and/or complex structural components is today non-trivial and far-too expensive, due to limitations in the state-of-the-art production processes. Swarm robotics could then bring a different perspective and it may promise flexible, autonomous, and highly robust solutions for a large variety of applications; hence, its adoption in industry and construction may change manufacturing rules. The present contribution introduces a continuous model to capture the behavior of a swarm of manufacturing agents (e.g., drones, 3D printers, etc..) as well as a very simple, but effective, numerical implementation to simulate the evolution of such a swarm. The paper also presents one- and two-dimensional examples, showing the potentiality of the proposed approach in predicting swarm behaviors. [ABSTRACT FROM AUTHOR]

In this paper, the construction of the original "Harten–Lax–van Leer" method using a piecewise-linear reconstruction of physical variables is described. The thus obtained numerical method makes it possible to reproduce the pressure, density, and velocity profiles with low dissipation at the discontinuities. To verify the method, classical problems of discontinuity breakdown are used with analytical solutions based on various configurations of shock waves, contact discontinuities, and rarefaction waves. The order of accuracy of the numerical method is studied using a Sod-type problem. It is shown that the greatest decrease in the order of accuracy is when a rarefaction wave is reproduced. The numerical method is verified by means of a three-dimensional Sedov test of a point explosion and a problem of a supernova Ia type explosion with two symmetric ignition points leading to the formation of a G1.9+0.3-type remnant. [ABSTRACT FROM AUTHOR]

The paper presents a numerical finite difference model of self-boring pressuremeter test (SBPM) using FLAC software. Different cavity expansion theories in sand have been compared to the results of numerical analyses carried out in this study. Limit pressure is believed to be used as a key parameter for the estimation of soil parameters from pressuremeter tests. In practice, SBPM tests are conducted up to 10-15% cavity strains, and the strain level associated with the limit pressure state is not reached. Therefore, determination of limit pressure usually needs extrapolation. In this paper, the authors suggest to use cavity pressure at 10% strain ( P ) for the interpretation of in situ horizontal stress from SBPM test rather than limit pressure. For this purpose, more than 5000 numerical analyses of SBPM are carried out, and cavity pressures associated with 10% strain are deduced. Based on these extensive numbers of numerical analyses, a new relationship is established with the aid of genetic algorithm which correlates P to soil parameters. The estimated values of P from the proposed relationship are compared to a large database of measured ones obtained from laboratory and field results available in the literature. It was shown that the proposed relationship gives satisfactory predictions of P . A chart was established for deduction of the in situ horizontal stress using the proposed relationship. This method can be used as a complement to liftoff method which is not reliable for estimation of the in situ horizontal stress when soil disturbance occurs at cavity wall. [ABSTRACT FROM AUTHOR]

This paper presents the results of a finite-element study of elastic-plastic deformation and damage accumulation in structural materials under various cyclic loading conditions. Material behavior is described by the relations of damage mechanics using thermoplastic model which takes into account the plastic deformation of material under cyclic loading and the kinetic equations of the energy theory of damage accumulation. The basic laws of plastic deformation and development of damage in materials under hard, soft, symmetric, and asymmetric low-cycle loading are established. [ABSTRACT FROM AUTHOR]

The availability of computer tools able to describe the behavior of pyroclastic density currents (PDCs) with uncertainty quantification is of primary importance for the assessment of volcanic hazard. A common strategy to assess the intrinsic variability of these phenomena is based on the analysis of large sets of numerical simulations with variable input parameters. The use of models fast enough to allow for a large number of simulations, such as the so-called kinetic energy models, is thus advantageous. Due to the sensitivity of kinetic energy models to poorly constrained input parameters, the definition of their variation ranges is a critical step in the construction of hazard maps and a numerical calibration becomes necessary. We present a set of reproducible and structured calibration procedures of numerical models based either on a reference deposit or on the distribution of runout distance or inundation area of documented PDCs. In the first case, various metrics can be adopted to compare the model results with the reference PDC deposit (root mean square distance, Hausdorff distance, and Jaccard index), facilitating the development of scenario-based hazard assessments. Calibrations based on the distribution of runout distance or inundation area allow the construction of probabilistic hazard maps that are not conditioned on the occurrence of a specific scenario, but rather reflect the variability of the documented PDCs during the time window considered. Importantly, our calibration strategies allow one to set the input parameters considering their potential statistical dependence. These procedures have been implemented on the user-friendly versions of two kinetic energy models: ECMapProb 2.0 and BoxMapProb 2.0, whose functionalities are presented for the first time in this paper. The different calibration strategies and the functionalities of the two programs are illustrated by considering three case studies: El Misti (Peru), Merapi (Indonesia), and Campi Flegrei (Italy). Highlights: • We present a set of structured and reproducible strategies to calibrate PDC numerical models. • We implement these calibration strategies on two user-friendly kinetic energy models: ECMapProb 2.0 and BoxMapProb 2.0. • These calibration strategies reduce the biases derived from user choices in the construction of hazard maps. [ABSTRACT FROM AUTHOR]

The paper presents an efficient numerical technique for 3D-modeling of seismic stability of large buried structures. This technique allows considering the subsoil-structure contact interaction, gravity field effects, the inhomogeneous structure of soil and the varieties location of the earthquake hypocenter. As part of this technique is substantiated sizing of the soil-structure computational domain and continuum model for hard and soft soil foundations describing. The numerical technique for determining the kinematic conditions at the lower boundary of the computational domain from the experimental accelerations at the soil surface is given, offered special non-reflecting waves boundary conditions. The methods described above and algorithms for seismic resistance solving have been implemented in certified software package "Dynamica-3", parallelization of the algorithm has been held according to the spatial domain decomposition principle. The developed numerical technique allows correctly posing the problem of seismic vibrations of buried structure, reducing computing costs and increasing the efficiency of numerical studies of Earthquake Engineering. Through this, the multiple recalculation of the task with different action scenarios generated from experimental seismograms by probabilistic methods became technically possible. The results of these calculations allow reflecting the experience of many earthquakes, which increases reliability of the estimates. The paper presents the model calculations results of seismic stability of large-sized buried structure—the mutual vertical and horizontal displacement of soil and building walls—which can then be used to assess strength of adjacent underground pipelines. A number of numerical experiments on seismic vibrations of nearby large-sized structures have been carried out to assess the mutual influence of structures on their behavior in an earthquake. It is established that the influence of nearby large-sized objects on seismic vibrations of structures differs for different buildings. [ABSTRACT FROM AUTHOR]

The paper presents the problem formulation and methods of numerical solution for a dynamical global model of the F layer of the Earth's ionosphere (altitude 100–500 km), which is a computational unit of the coupled thermosphere–ionosphere model. The model is based on a system of equations of the global ionospheric formation and dynamics in a spherical geomagnetic coordinate system in the approximation of a thin spherical layer. The features of the formulated system of equations are investigated and the methods for its solution are proposed based on the method of splitting them by physical processes. In this paper we present the results of a single step of the splitting method—the solution of equations which describe the ambipolar diffusion of ions along the magnetic field lines and the gravitational settling of ions, as well as the plasma–chemical transformations. The accuracy of the proposed algorithms is investigated based on the prescribed analytical solution, which qualitatively correctly describes the real ionospheric electron distribution. The results of the numerical experiments on studying the sensitivity of the solution to perturbations of the ion flow at the upper boundary are provided. [ABSTRACT FROM AUTHOR]

In the paper, a method of automatic choice of the boundary conditions is presented. This method allows the initial estimation the value of the boundary conditions during the heating operation for the welding process. The solutions described in this paper can successfully support the work of the specialists performing numerical simulations. They also significantly reduce the time required to estimate the boundary conditions parameters consistent with the actual experiment. The accuracy of the solution in the presented method is not dependent on the empirical models of boundary conditions for the heating process. It is also much more universal. Artificial neural networks after the learning process can be used to perform a reverse analysis for the heat treatment process, for example, to determine the parameters of welding process in the production process of steel elements. [ABSTRACT FROM AUTHOR]

The laser powder bed fusion (LPBF) process involves using a laser beam to selectively melt metal powder with a desired shape on a substrate to create a part layer-by-layer. As an Additive Manufacturing (AM) process, laser powder bed fusion (commonly referred to as selective laser melting—SLM) offers superior design freedom over conventional manufacturing methods and enables the production of complex, lightweight geometries with applications in the aerospace, automotive, and biomedical industries. In addition to enhanced design freedom, AM technologies provide improved material utilization and allow for reduced assembly needs. However, the reliability and repeatability of additively manufactured parts is a challenge to the wide-scale adoption of the technology for safety critical parts. A critical limitation of process optimization is the prediction and control of residual stresses, distortion, and microstructure evolution. This work focuses on the development and implementation of a numerical modeling technique for the prediction of residual strains within an Inconel 625 LPBF part. The model, using the SIMULIA Additive Manufacturing Scenario App, based on the Abaqus 2018 finite element solver, was developed and analyzed as part of a submission for the NIST AM Benchmark 2018. A sequentially coupled thermo-mechanical analysis was adopted to replicate the building conditions of a single cantilever beam built at the NIST laboratories. The results of the blind study were compared to X-ray diffraction (XRD) measurements of the physical build. The predicted three-dimensional residual strain field showed a high level of accuracy and the submission described in this paper received joint first prize in the residual elastic strain category of the NIST AM Benchmark 2018. The results presented in this paper reflect only findings before the benchmark measurements were posted on the NIST website. [ABSTRACT FROM AUTHOR]

Composite materials, due to their properties (high specific strength and low weight), are currently among the most demanded materials used in creating objects for many purposes. The strict modern safety standards require timely monitoring of the occurrence and development of defects, in particular, delaminations. In this respect, considerable attention is paid to the development and improvement of methods of flaw detection. This paper presents a numerical study of the possibility of detecting and localizing delaminations in structures made of laminated composite materials by using vibrational approaches. The approach proposed is based on the excitation of vibrations with an increased amplitude in the region of the defect. This is possible due to the rise of natural vibration frequencies, the maximum amplitude of which is localized exactly in this place. In the first stage of numerical experiments, it was found that such natural frequencies depend weakly on the location of the defect but are strongly correlated with the size of the delamination. In the next stage, for an adequate description of the vibrational processes in the structure, forced steady-state vibrations were simulated taking into account the necessary dissipative parameters of the composite material. The frequency of the external action was chosen in accordance with the natural vibration frequency corresponding to the defect obtained from the modal analysis. The calculation results showed a significant increase in the vibration amplitude in the delamination region in comparison with the defectless structure if the frequency of the external action is chosen correctly. The effectiveness of the approach depending on the distance from the place of the application of the forced oscillation to the delamination region was tested. The method of defect monitoring proposed in the paper makes it possible to justify the possibility of developing, based on the vibtrational processes, a system for detecting delaminations in composite materials and to determine the main parameters of such a system. [ABSTRACT FROM AUTHOR]

In this introduction we briefly summarize the fourteen contributions to Part II of this special issue on Tsunami Science Four Years After the 2004 Indian Ocean Tsunami. These papers are representative of the new tsunami science being conducted since the occurrence of that tragic event. Most of these were presented at the session: Tsunami Generation and Hazard, of the International Union of Geodesy and Geophysics XXIV General Assembly held at Perugia, Italy, in July of 2007. That session included over one hundred presentations on a wide range of topics in tsunami research. The papers grouped into Part II, and introduced here, cover field observations of recent tsunami’s, modern studies of historical events, coastal sea-level observations and case studies in tsunami data analysis. [ABSTRACT FROM AUTHOR]

The state of the natural environment of the marginal seas of the Northwest Pacific is largely controlled by the interaction of the atmospheric and hydrophysical processes. Tropical cyclones (typhoons), originating in the tropical zone of the Northwest Pacific and over the South China Sea basin, occupy a special place among atmospheric processes. The main destructive impact of typhoons falls on Southeast Asia. However, a significant number of are moving to the Russian Far East. The region of the South China Sea plays a significant role in the formation of tropical cyclones. This determines the importance of studying hydrometeorological processes not only in the Far East, but also in the South China Sea, and the need for cooperation between Vietnamese and Russian scientists. The main hydrodynamic structure of the western South China Sea is the Vietnamese Coastal Current (Western Boundary current), which depends not only on the seasonal monsoons but also on typhoons. The paper presents the results of joint Russian–Vietnamese studies of the dependence of the vertical structure of the Vietnamese Coastal Current on the Pacific tropical cyclones that form in the South China Sea. The study is done with numerical modeling. The period from April to June 1999 was used for modeling, provided with the necessary field data. The simulation results showed that, in general, the structure of water masses depends on the trajectories of tropical cyclones. In all cases considered, the Vietnamese Coastal Current is not a single flow, but represents a zone of eddy structures of different directions. An exception is the only situation in the condition of a tropical cyclone in the central region of the South China Sea when this current acquired the form of a single continuous flow directed from north to south only in the 200-m layer. The general patterns of changes in the dynamic structure of the Vietnamese Coastal Current for all the considered tropical cyclone trajectories include the following: areas with water transport in the northern direction prevail on the surface, while the rest of the water mass continues to flow generally in the southern direction. This transport of surface waters may be due to the influence of the emerging summer monsoon, and the rest of the water mass, which is less exposed to the still weak atmospheric processes of the monsoon type, continues to flow in the winter regime. [ABSTRACT FROM AUTHOR]

The paper presents the mathematical model, numerical algorithm and results of parametric study for the parameters of multi-nozzle solid propellant propulsion supplied with the stepper regulators of mass flow rate. [ABSTRACT FROM AUTHOR]

Developing countries face risks from coastal hazards that are being amplified by climate change. The selection of effective adaptation interventions to manage these risks requires a sufficiently accurate assessment of the coastal hazard at a given location. Yet challenges remain in terms of understanding local coastal risks given the coarseness of global wave models and the paucity of locally scaled data in most developing countries, including Small Island Developing States (SIDS) like Vanuatu. This paper aims to examine the differences in hazard assessment and adaptation option selections arising from analyses using globally versus locally scaled data on coastal processes. As a case study, we focused on an eroding cliff face in Port Resolution on Tanna Island, Vanuatu, which is of concern to the local community and government authorities. The coastal process modeling revealed that the global wave data generated unrealistically high predictions of wave height within Port Resolution Bay. Expensive engineering adaptations designed to provide coastal protection were therefore likely to fail in preventing ongoing cliff erosion. In this case, the best adaptation solution involves changing land use to revegetate and help stabilize the cliff top. Our case study highlights the importance of accurate hazard assessment, especially in data-poor regions where the extrapolation of global datasets and models in the absence of local data can result in poor adaptation decision-making. Furthermore, the multidisciplinary approach applied here can be applied in other data-poor regions to strengthen analyses exploring the benefits of local adaptation interventions. [ABSTRACT FROM AUTHOR]

During polar nights in January 2012 and 2017, significantly higher bioluminescence (BL) potential emissions in the upper 50 m were observed in the fjord Rijpfjorden (Svalbard, Norway) in comparison to offshore stations (located on the shelf-break, shelf-slope areas and in the deeper water). The objective of this paper is to better understand why, during two polar nights (separated by 5 years), the values of BL potential in the northern Svalbard fjord are higher than at offshore stations, and what the role of advection is in observed elevated BL potential values in the top 50 m of the fjord. To address the above objective, we applied the same BL potential modeling approach and strategies during polar nights for both 2012 and 2017. For both years, advection of BL potential from offshore (including upwelling along the shelf, shelf-slope) produced an increase of BL potential in the fjord area, in spite of the introduction of mortality in bioluminescent organisms. Observations of BL potential indicated high emissions at depths below 100 m at offshore stations for both polar nights. Our modeling studies demonstrated that these high values of BL potential below 100 m are upwelled and advected to the top 50 m of the fjord. We demonstrated that upwelling and advection of these deep high BL potential values (and therefore, upwelling and advection of corresponding bioluminescent taxa) from offshore areas are dominant factors in observed BL potential dynamics in the top 50 m in the fjord. [ABSTRACT FROM AUTHOR]

A methodology is presented for tuning the main parameters of the r-solution method as applied to the problem of reconstructing the initial tsunami waveform. Based on singular value decomposition, the r-solution method provides an effective means for controlling the instability inherently present in the inverse problem. However, the quality of the inversion depends heavily on the main parameters of the method, which are the number of the right singular vectors which form the basis of a solution space and the number of spatial harmonics used in the tsunami source representation. Unlike previous studies, where these factors were analyzed separately, in this paper they are considered jointly, which allows one to discover the mutual connections between them. The latter makes it possible to improve the inversion results. An optimal number of spatial harmonics decreases the time for matrix calculation and reduces the number of inversion artifacts. The approach for choosing the optimal parameters is illustrated by a case study of the Illapel Tsunami of 2015. [ABSTRACT FROM AUTHOR]

The valve is one of the important parts of the engine, and 21-4N is the main material of the engine valve. In the die forging process, accurate process parameters are required to ensure that the engine valve parts that meet the requirements can be obtained. In this paper, the thermal simulation experiments are conducted to obtain stress–strain data of 21-4N heat-resistant steel at a deformation temperature of 1273–1453 K and a deformation rate of 0.01–10 s−1. And hot processing maps are used to optimize the die forging process of 21-4N. The numerical simulation of valve die forging based on the optimized parameters obtained from the thermal processing maps is conducted, and the forming rules are studied. The influence law of die forging temperature, die forging speed, and friction coefficient is analyzed and finally verified in valve processing enterprises. [ABSTRACT FROM AUTHOR]

Low entropy shallow ground heat resources are gaining importance in recent years owing to their availability compared to difficult-to-reach geothermal energy sources. In the last decades, aquifer thermal energy storage (ATES) systems have begun to be utilized increasingly since they can provide one of the cleanest and most energy efficient heating and cooling system alternatives for buildings. One of the main problems in the design phase of ATES systems is the correct estimation of thermal interference distance between extraction and injection side of the system. In order to investigate this problem, an extensive modeling study was carried out to constitute a preliminary approach for the numerical model calibration of heat transport and storage in aquifers. For this purpose, actual site data available for a well-studied coastal aquifer in Mediterranean region of Turkey was used in the analysis and performance assessment of a conceptual open-loop ground source heating well doublet. Three-dimensional coupled numerical model of groundwater flow and heat transfer was produced to constitute an approach for the thermo-hydraulic model calibration by estimating the duration of thermal breakthrough between the abstraction and injection wells. Simulation results were compared with the analytical solution for doublet well breakthrough time with finite hydraulic gradient. The comparison of results indicated that the numerical model is able to represent the thermal behavior in the field. Therefore, calibration methodology established in this paper could be followed in the pre-feasibility study and the design phase of low-temperature aquifer thermal energy storage systems worldwide. [ABSTRACT FROM AUTHOR]

This paper presents a parametric study of the optimization design for T-shaped deep cement mixing (TDM) and conventional deep cement mixing (DCM) columns improved soft soil for supporting embankments. The objective of the optimization was to find the best compromised solution for the cost effectiveness in conjunction with minimizing the serviceability limit state (SLS) requirements (i.e., settlements, differential settlements, and lateral movements) while maximizing the ultimate limit state (ULS) requirement (i.e., factor of safety against bending failure). A combination between a genetic algorithm and the response surface method was employed as an optimization approach for determining the optimal solution. The relations and interpretations between design column parameters and design requirements are presented and discussed through parametric studies. The optimization results indicate that the optimal TDM column can allow to permit a lower construction cost than the optimal DCM one. [ABSTRACT FROM AUTHOR]

In this paper, the structural behavior of masonry panels strengthened with a system made up of composite fiber grids embedded in a cementitious matrix (FRCM) is presented. The non-linear behavior of the unreinforced and reinforced panels is numerically simulated by means of a simplified micro-modelling approach. This approach concentrates all the non-linearities and failures in the joints and in potential crack surfaces within the bricks, placed vertically in the middle of each brick. The FRCM strengthening system is discretized by a continuous bi-directional fiber grid constituted by trusses embedded into a cementitious matrix. A calibrated bond-slip relationship is applied between the fibers and the mortar matrix assuming an idealized bilinear law. The typical experimental load–displacement curve for a FRCM strengthened panel shows three principal phases that correspond to different failure mechanisms: masonry cracking, mortar matrix cracking and ultimate failure of the panel. The non-linear numerical analyses show a good agreement with experimental results and the modeling approach is found to be adequate to reproduce the described experimental behavior. The results of a parametric study on both the material and the geometrical properties of the FRCM system are also presented. [ABSTRACT FROM AUTHOR]

Directional fracture controlled blasting technology plays a significant role in rock blasting engineering, in which the shaped charge forms are usually utilized. The energy-gathering form of shaped blasting still has no unified and strict standard currently, which can be optimized to save charge materials and improve blasting efficiency by a further study. In this paper, the breaking mechanism of rock blasting using the general cylindrical Bilateral-Groove (the groove is in "V" shape) Shaped Charge (BGSC) approach was analyzed theoretically. Several cases with different energy-gathering forms using rock drilling and blasting method were tested by numerical modeling, and then an innovative approach of BGSC was determined through comprehensive comparative analyses. It was found that the optimal blasting effect, which has the longest directional cracks, few non-directional cracks and light damage to the surrounding rock, can be achieved by decoupling Bilateral–Groove-Slot Shaped Charge (BGSSC) blasting. Then the decoupling BGSSC approach was adopted to study the timing sequence effect in microsecond magnitude for double-borehole rock blasting. The results of the numerical tests indicated that acceptable blasting effect with a good through crack and less damage in surrounding rock could be captured when the delay time is located in 0–40 μs and 600–800 μs, which have a consistent changing tendency of the effective stress and lower oscillation range than the other delay schemes. This study can provide important theoretical bases for the development of blasting engineering technology on the aspects of shaped charge form and short time delay blasting scheme. [ABSTRACT FROM AUTHOR]