Displacement Zone Research Articles

Study on the Stability of Bearing Load Slope under Earthquake Based on Quasi-Static Force Method

Quasi-static method originated from the safety evaluation of structural engineering under earthquake. Compared with the time history analysis method, quasi-static calculation is simple and quick, and gradually applied in the analysis of slope stability. This article combined quasi-static method with three-dimensional finite difference method (FLAC3D), and applied it in the seismic stability study of a slope. The slope has a convex shape. Two tunnel anchorages and four bridge foundations built in central of it bearing bridge load, so it is a typical bearing slope. This article put forward a numerical calculation failure criterion to the slop of this type by calculating and analyzing the stress, displacement and plastic zone distribution characteristics when it under earthquake, and gave out the slopes seismic safety coefficient. The research results of this paper can provide a useful reference for the similar projects.

Rock permeability in displacement zones at coal deposits: A case study of underworked inundated mines

Rock displacement in some sites of coal mines is accompanied by changes in the permeability and fil� tering structure of the host rock massif. Transforma� tion of a massif resulting from the appearance of such hydrogeological channels significantly affects the con� ditions and environmental impact of mining; such a channel provides water flow through it and is called a “zone of water conducting displacement cracks” (ZWCDC). The maximal changes take place at the sites of a collapsed mine roof. The operational practice has revealed the ability to keep the minimal increment in through permeability of a dividing rock mass within the ZWCDC and to pre� serve the zones of minimal permeability values within the massif. These conclusions, supplemented with the studies of cracked structures based on equivalent material models, were also reported in [1] and became standard for Russian norms regarding the determination of coal extraction conditions near water objects.

Recent geodynamics of the faults and paradoxes of the rates of deformation

The results of analyzing the long (20–50 years) time series of geodetic observations carried out in the regions with enhanced seismotectonic activity (Kopet Dag, Kamchatka, and California) are presented. It is established that recent vertical and horizontal displacements in the fault zones estimated by instrumental geodetic observations with increased spatiotemporal resolution indicate that the deformations in the fault zones paradoxically deviate from the movements inherited from the previous geological epochs.

Numerical Estimation of <i>J<sub>IC</sub></i><sub> </sub>of a Ductile Metal

The paper presents a numerical technique to estimate the critical value of J integral, of a ductile metal (Aluminum alloy). Cracked, Single Edge Notch Bend (SENB) specimen of the alloy is modeled by finite element method. Load over the specimen is chosen such that the process or fracture zone is generated at the crack tip. The load is subsequently increased for the process zone size to go up. Process zone sizes and displacements under loads are measured from post processor solutions. Resistance curve and blunting line are plotted. Intersection of the two provides the value of. equals upon fulfillment of the plane strain condition. Various thickness values of the specimen are tried. The value of KIC obtained from is found to be in close agreement with the reported value obtained from experiments.Nomenclature

Research on Optimization of Excavating Seguence for Dawangou Tunnel

In response to the limitation of conventional index for stability and optimal design of underground rock mass engineering. The new evaluating indicator, local energy release rate, which can analysis the energy release intensity in the process of the brittle failure of hard rock is used in numerical analysis. Numerical simulation of construction sequence was studied for Dawangou tunnel using energy release rate index and a new constitutive model reflecting the brittle failure of hard rock. Based on the change trend of energy release rate, rock displacement and plastic zone, an optimization excavation is suggested. The optimal excavating sequence could serve as reference in the design and construction.

3D Simulation of Mechanised Excavation in Brittle Rock

During the excavation by TBM of the Aicha Exploratory Tunnel along the Brenner Base Tunnel in Italy, in hard brittle granitic rocks, an instability phenomenon occurred at chainage 6+151. The left-hand sidewall lining partially collapsed for a length of approximately 60m. This led to a stoppage of the TBM lasting about 4 months. With the reconstruction of the geological model, a sub-vertical fault, not forecast at the design stage, was identified parallel to the direction of the excavation. In this paper, a three-dimensional (3D) model, which simulates the complex interaction between the rock mass, the TBM and its system components, and the tunnel support, is presented. The model accounts for the main machine components: shields, cutterhead, grippers, pea gravel and lining. The brittle failure of a thin granite diaphragm between the fault zone and the tunnel wall is reproduced and the results are discussed in terms of failure zone and horizontal displacements.

Cenozoic structural deformation and expression of the “Tan-Lu Fault Zone” in the West Sag of Liaohe Depression, Bohaiwan basin province, China

Based on the interpretation of 3D seismic data and structural mapping we analyzed the geometry and kinematics of the fault system and validated the expression of the “Tan-Lu Fracture Zone” in the West Sag of Liaohe Depression, Bohaiwan basin province. The Cenozoic structural deformation within the West Sag of Liaohe Depression can be divided into extensional structure system and dextral structure system. The extensional system is constituted by numerous NNE-NE trending Paleogene normal faults, where the Taian-Dawa fault (F1) is the master boundary fault (MBF) dominating the deposition during Paleogene so that the sag shows a complex half-graben with “boundary fault in the east and overlap in the west”. The dextral system is constituted by 2–3 dextral basement faults in NNE-NE trending (F2, F3, F4) and associated structure, and the time of structural action started in Oligocene and continued to Quarternary so that some associated secondary faults of the dextral system cut off the Neogene and Quaternary. Under the influence of the position and attitude of NNE-NE trending basement strike-slip faults, the central north part and the south part of the West Sag show obviously different structural features. The former appears to be a complex “graben” structure limited by the reversed strike-slip fault in the west and bounded by the inverted normal fault in the east, the latter remains the complex half-graben structure with “boundary fault in the east and overlap in the west”, and the graben was mildly reconstructed by one or two normal strike-slip faults. The dextral system within the West Sag is the element of the west branch fault of the Tan-Lu Fracture Zone, which is a deep fracture zone extending along the east of the Liaodongwan Gulf. The deep fracture zone branches off into two separate faults within the Liaohe Depression. The east branch goes through from northern part of the Liaodongwan Gulf to the East Sag of Liaohe Depression and links with the Denghua-Mishan Fault near Shenyang, and the west branch passes from northern part of the Liaodongwan Gulf to the West Sag and Damintun Sag of Liaohe Depression and links with the Yilan-Yitong Fault. The principal displacement zone of the west branch of the Tan-Lu Fracture Zone cuts off the master extensional fault (F1) within the West Sag of Liaohe Depression and induces many cover faults in EW trending within the Neogene and Quaternary.

Elastoplastic orthotropic shell with an internal crack of arbitrary configuration

We have developed methods of constructing systems of singular integral equations for solving the problems of the stressed state of orthotropic shells of arbitrary curvature with an internal crack of arbitrary configuration. The influence of elastic and geometric parameters of shells on the size of the plastic zone and crack opening displacement has been considered. Shell structures often contain crack-like defects, and cracks present in them can be through and internal. Methods and models which will be used in the strength analysis of these structures depend on the type of the crack. In calculations, it is important that the chosen method or model be well defined in using and describe adequately the mechanical problem [8]. An analog of the δ c -model, using which, one can simultaneously take into account both the type of the crack and plastic deformations that arose in the vicinity of it was developed by Folias and Erdogan [7] and used by many scientists in the investigation of isotropic and orthotropic shells of certain and arbitrary curvature with internal cracks [2–4]. However, in all indicated investigations, the contour of the depth of an internal crack was modeled by a rectangle, which substantially simplified the solution of the problem, but the shape of the real crack was not taken into account. In the present work, the contour of the depth of a crack is described by two smooth curves. We perform a comparative analysis of results obtained under the assumption that the contour of the depth of the crack is rectangular or parabolic. Statement of the Problem

Pre-fracture zone model on electrically impermeable and magnetically permeable interface crack between two dissimilar magnetoelectroelastic materials

A plane strain problem for two magnetoelectroelastic half-planes adhered by a thin isotropic interlayer is considered. A novel crack model, i.e., an interface crack with pre-fracture zones is introduced for magnetoelectroelastic bimaterial system. Both the stresses, electrical displacements in pre-fracture zones and the lengthes of pre-fracture zones are unknown, which are determined by solving the corresponding Hilbert problem and solving nonlinear equations introduced by yielding condition on the pre-fracture zones. Finally, the case for symmetrical loads is analyzed and numerically discussed. Some important conclusions are drawn. Among others, in the suggested model, any singularities connected with the crack are eliminated. Results presented in this paper should have potential applications to the design of multilayered magnetoelectroelastic structures and devices.

Stability of coal pillar in gob-side entry driving under unstable overlying strata and its coupling support control technique

Considering the situation that it is difficult to control the stability of narrow coal pillar in gob-side entry driving under unstable overlying strata, the finite difference numerical simulation method was adopted to analyze the inner stress distribution and its evolution regularity, as well as the deformation characteristics of narrow coal pillar in gob-side entry driving, in the whole process from entry driving of last working face to the present working face mining. A new method of narrow coal pillar control based on the triune coupling support technique (TCST), which includes that high-strength prestressed thread steel bolt is used to strain the coal on the goaf side, and that short bolt to control the integrity of global displacement zone in coal pillar on the entry side, and that long grouting cable to fix anchor point to constrain the bed separation between global displacement zone and fixed zone, is thereby generated and applied to the field production. The result indicates that after entry excavating along the gob under unstable overlying strata, the supporting structure left on the gob side of narrow coal pillar is basically invalid to maintain the coal-pillar stability, and the large deformation of the pillar on the gob side is evident. Except for the significant dynamic pressure appearing in the coal mining of last working face and overlying strata stabilizing process, the stress variation inside the coal pillar in other stages are rather steady, however, the stress expansion is obvious and the coal pillar continues to deform. Once the gob-side entry driving is completed, a global displacement zone on the entry side appears in the shallow part of the pillar, whereas, a relatively steady fixed zone staying almost still in gob-side entry driving and present working face mining is found in the deep part of the pillar. The application of TCST can not only avoid the failure of pillar supporting structure, but exert the supporting capacity of the bolting structure left in the pillar of last sublevel entry, thus to jointly maintain the stability of coal pillar.

Evaluating the impact of aquifer layer properties on geomechanical response during CO2 geological sequestration

Numerical models play an essential role in understanding the facts of carbon dioxide (CO2) geological sequestration in the life cycle of a storage reservoir. We present a series of test cases that reflect a broad and realistic range of aquifer reservoir properties to systematically evaluate and compare the impacts on the geomechanical response to CO2 injection. In this study, a coupled hydro-mechanical model was applied to simulate the sequestration process, and a quasi-Monte Carlo sampling method was employed to efficiently sample the value of aquifer properties and geometry parameters. Through quantitative sensitivity analysis, the impacts of all the input parameters are ranked. Aquifer permeability was found to be of significant importance to the geomechanical response to the injection. To study the influence of uncertainty of the permeability distribution in the aquifer, an additional series of tests is presented, based on a default permeability distribution site sample with various distribution deviations generated by the Monte Carlo sampling method. The results of the test series show that the uncertainty of permeability distributions significantly affect the displacement and possible failure zone.

Contact Problem for an Elastic Layer on an Elastic Half Plane Loaded by Means of Three Rigid Flat Punches

The frictionless contact problem for an elastic layer resting on an elastic half plane is considered. The problem is solved by using the theory of elasticity and integral transformation technique. The compressive loadsPandQ(per unit thickness in direction) are applied to the layer through three rigid flat punches. The elastic layer is also subjected to uniform vertical body force due to effect of gravity. The contact along the interface between elastic layer and half plane is continuous, if the value of the load factor,λ, is less than a critical value, . In this case, initial separation loads, and initial separation points, are determined. Also the required distance between the punches to avoid any separation between the punches and the elastic layer is studied and the limit distance between punches that ends interaction of punches is investigated for various dimensionless quantities. However, if tensile tractions are not allowed on the interface, for the layer separates from the interface along a certain finite region. Numerical results for distance determining the separation area, vertical displacement in the separation zone, contact stress distribution along the interface between elastic layer and half plane are given for this discontinuous contact case.

Friction force model and rolling dynamics for a ball on a rough surface with presliding displacement taken into account

A model of sliding and spinning friction forces for a ball in the form of finite relations obtained by integrating the tangential stresses over the contact area whose parameters are determined by Hertz’s theory for the “ball-rough horizontal surface” tribological conjunction pair is supplemented with a model of rolling friction torques. The combined model is peculiar in that the presliding displacement effect in rolling and spinning friction torques is taken into account. It is shown that the ball motions in the presliding displacement zone are of quasilinear character and, under shock perturbations, have the form of damping vibrations in the three orientation angles. The numerical parameters of the rolling and spinning friction model are experimentally determined for the presliding displacement zones, while the sliding friction parameters and partly the spinning friction parameters are calculated. Mathematical modeling permits one to discover new properties of the ball, namely, its deceleration in rolling, the onset of damping vibrations at the beginning and end of motion, and the transient process parameters.

1073 – Assessment of behavioral symptoms in dementia patients with the help of ICTs

Behavioral and psychological symptoms in dementia patients (BPSD), represent a strong predictor of dementia progression. Current interview-based assessment methods lack objectivity to ensure reliable early differential detection. Therefore, the use of Information and Communication Technologies (ICT) such as actigraphy and automatized video monitoring are of interest in addition to current assessment methods because they allow capturing the patients’ performances and actions in real time and real life situations. To improve the quality of clinical assessments of BPSD by validating the use of objective measurements obtained by ICTs in dementia patients in an experimental design, undergoing an „ecological assessment“. Demented and pre-demented patients (with and without apathy) and healthy controls underwent an experimental trial wearing an actigraph and being filmed over a free period of 15 minutes in a in 16-zone divided room. Apathy was assessed using NPI apathy subscore. Frequency of zone displacement, and of goal-oriented zones, object manipulation, mean motor activity and speed of walking were assessed with the help of ICT. Significant differences were found between apathy and non-apathy AD patients for the parameter of object manipulation (OM) and OM in goal-oriented zones (GOZ) but not for frequency of zone displacement (FZD). Moderate evidence for a reliable detection of apathy in dementia patients through data obtained by ICTs was found. Therefore, it represents a promising addition to conventional neuropsychological methods for future studies, focusing in particular on object manipulation and visuomotor deficits.

Active faulting in the north-eastern Aegean Sea Islands

Abstract The distribution of seismicity, faulting pattern and its effect on local geomorphology is examined for the islands of Lemnos, Aghios Efstratios, Lesvos, Chios, Samos and Ikaria of north-eastern Aegean Sea, Greece. The main active faults on each island are described in terms of their geometrical characteristics and geomorphology. Faults that comply with specific criteria (geological age, effect on relief, their geometrical relationship to the active stress field) have been characterized as active. We evaluated and reviewed published information, augmented with new field data for onshore faults, while the effects of faulting on the sea-floor and their probable association with recorded earthquakes were used to determine offshore faulting. The relation of active faulting to the stress pattern has been examined as well. It is shown that as the deformation changes gradually from transtensional in the north to extensional in the south, so does the active faulting pattern. The effect of the westernmost splays of the North Anatolian Fault Zone, the largest of which is the ~ 300 km long, North Aegean Trough, is profound due to their close vicinity, causing shearing in good agreement with the modeled principal displacement zone deformation pattern. Faulting in the area is controlled by the distance from the main dextral principal displacement zones: the northern part of the area is directly affected by the North Anatolian Fault Zone and its splays, while this effect gradually weakens in the central and southern areas. The geomorphology responds to this faulting, causing the formation of fault-parallel gulfs near Lesvos and Lemnos and fault-defined shorelines in the rest of the islands. Ikaria exhibits a notable fault-controlled tilted topography as the result of footwall uplift.

The effect of early operative stabilization on late displacement of zone I and II sacral fractures

IntroductionThis study was designed to evaluate the effect on displacement of early operative stabilization on unstable fractures when compared to stable fractures of the sacrum. MethodsPatient consisted of those sustaining traumatic pelvic fractures that also included sacral fractures of Denis type I and type II classification, who were over 18 at the time of the study. Patients were managed emergently, as judged appropriate at the time and then subsequently divided into two cohorts, comprising those who were either treated operatively or non-operatively. The operative group comprised those treated with either internal fixation or external fixation. ResultsTwenty-eight patients had zone II fractures, and 20 had zone I fractures. Zone II fractures showed average displacements of 6.5mm and 6.9mm in the rostral–caudal and anteroposterior directions, respectively, at final follow up. Zone I fractures had average displacements of 6.6mm and 6.1mm in both directions. There were no significant differences between zone I and II sacral fractures (rostral–caudal P=0.74, anteroposterior P=0.24). Average changes in fracture displacement in patients with zone I fractures were 0.6–1.0mm in both directions. Average changes in zone II fractures were 1.8–1.5mm in both directions. There were no significant differences between the average changes in zone I and II fractures in any direction (rostral–caudal P=0.64, anteroposterior P=0.68) or in average displacements at final follow up in any of zone or the entire cohort. Statistically significant differences were noted in average changes in displacement in zone II fractures in the anteroposterior plane (P=0.03) and the overall cohort in the anteroposterior plane (P=0.02). ConclusionOperative fixation for unstable sacral fractures ensures displacement at follow up is comparable with stable fractures treated non operatively.

Communication practices of the Karen in Sheffield: seeking to navigate their three zones of displacement

This study investigates communication practices of a newly arrived Karen refugee community in the UK who, as well as establishing themselves in a strange country, seek to keep in touch, campaign politically and maintain identity collectively through communication and contact with their global diaspora. We look at the technologies, motivations and inhibiting factors applying to the communication by adult members of this community and construct the idea of three zones of displacement which help to model the particular contexts, challenges and methods of their communication. We find that, overall, they are using a wide range of internet-based technologies, with the aim to ‘keep-in-touch’ (personal contacts) and to ‘spread the word’ (political communication). This also includes archaic, traditional and hybrid methods to achieve extended communication with contacts in other ‘zones’. We also identify the importance of the notion of ‘village’ as metaphor and entity in their conceptualisation of diasporic and local community cohesion. We identify the key inhibitors to their communication as cost, education, literacy and age. Finally, we speculate on the uncertain outcomes of their approach to digital media in achieving their political aims.

Smart Passive Vibration Isolation: Requirements and Unsolved Problems

Vibration isolators are needed to control the relative displacement, acceleration, or most importantly the transmitted force to the base or to the isolated device. As a general rule, a good vibration isolator should be as soft as possible to reduce the transmitted force, and it should be hard to limit the relative displacement. Soft suspension provides large relative displacement in resonance zone. To limit the relative displacement while having a soft suspension, a limiting displacement design is needed. There are two practical designs, Hydraulic Engine Mount (HEM) and Piecewise Linear Suspension (PLS) which are being used in industry since 80s. Hydraulic engine mounts were invented to passively produce a low damping at low amplitude and a high damping at high amplitude. Similarly, piecewise linear suspension were introduced to provide a soft suspension at low amplitude and a hard suspension at high amplitude. Having dual behavior puts both HEM and PLS in the domain of nonlinear system which in turn brings many new phenomena never appeared in linear analysis. This article will review the necessity of having a dual behavior suspension and the design of the two practical designs. However, both of these designs have some challenging and unsolved problems. Introducing the problems opens avenue for supervisors, researchers, and students to direct their research practice and hopefully solve them.

Numerical Simulation Analysis of the Nanyangpo Coal Mine Anchor Support Method

The bolt support is important to ensure the stability of surrounding rock. Of Nan Yangpo mines as the research background. The application of numerical simulation software FLAC3D mine deep Bolt bolt support after the surrounding rock deformation law of the numerical simulation, Comparison and analysis of rock displacement and plastic zone under the support program changes. The results show that, The third bolt support nursing program, Significantly improve the strength and load carrying capacity of the surrounding rock, Effectively control the damage of the deep tunnel deformation that can control the roof of 4101 the return airway and two to help the stability.

Earthquake and Underground Powerhouse: On the Aseismic Issues of Baihetan Underground Cavern Complex

A hydropower plant is usually the major electricity supplier in the region, the failure of underground powerhouse in an earthquake may cause not only the damage to itself, but also secondary disasters to the region in a way of an electricity outage. Seismic stability of these underground complexes is required to be seriously addressed. The underground cavern complex of the Baihetan hydropower plant in Yunnan Province, China, is currently the world's largest underground rock cavern group under construction. Aseismic issues of the underground cavern complex are discussed in this paper. On the basis of this research, seismic variables of the Baihetan project are firstly determined for Design Basis Earthquake and Safety Evaluation Earthquake. The artificial seismic motions for the dynamic analyses are simulated. Two alternative scheme of layout plans of the underground cavern complex are studied, with full 3-D elasto-plastic dynamic response analyses based on the parameters given by the cyclic dynamic loading tests with medium strain rate. The seismic response of seismic displacement and failure zones of each scheme are studied, respectively. A performance verification of the supporting measures during earthquake is also discussed. The results indicate that in spite a wider powerhouse cavern, the scheme "A" which involves a gallery-shaped surge chamber is more stabilized during an earthquake than the scheme "B" whom with barrel-shaped surge chambers. The underground cavern complex with scheme "B" is relatively stable under Design Basis Earthquake and Safety Evaluation Earthquake, despite a minor damage of the surrounding rock. And the implementation of the proposed support system may further guaranteed a safe state of the underground cavern complex in earthquake events.