scholarly journals Experimental Study on the Features of Infrasonic Waves of Sandstone under Shear Load

2021 ◽  
Vol 11 (23) ◽  
pp. 11552
Author(s):  
Chen Qiao ◽  
Fenglin Xu ◽  
Pengcheng Su ◽  
Yang Liu ◽  
Yifang Zhang ◽  
...  
Keyword(s):  
Shear Failure ◽  
Monitoring And Evaluation ◽  
Dominant Frequency ◽  
Shear Loading ◽  
Slope Instability ◽  
Dynamic Monitoring ◽  
Forming Mechanism ◽  
Infrasonic Waves ◽  
Study Results ◽  
Infrasonic Wave

The shear failure of rock is a major cause of rock slope instability and consequent landslides. To determine the forming mechanism of infrasonic waves during the loss of stability of sandstone slopes, experiments were carried out using a shear loading device and an infrasonic monitoring device. In the experiments, infrasonic wave events were identified, and the characteristic parameters of infrasonic waves were extracted to analyze the features of the infrasonic wave response during the shear failure of sandstone. The study results show that: (1) the whole process of shear failure was associated with infrasound events. A normalized energy cumulative coefficient of over 0.6 and a normalized infrasound rate of over 0.89 are the key time nodes for alarming landslide; (2) with an increase in sample size, the shear resistance of the sample increases logarithmically, the total energy of infrasound events increases exponentially, and the average dominant frequency of infrasound events decreases linearly; and (3) with an increase in axial pressure, the shear of the rock increases almost linearly, the number of infrasound events increases linearly, and the average dominant frequency of infrasound events increases exponentially. The research results provide important guidance for the dynamic monitoring and evaluation of the stability of sandstone slopes and can provide a theoretical reference for landslide alarming of sandstone slopes using infrasonic waves.

scholarly journals Monitoring and Analysis of Dynamic Characteristics of Super High-rise Buildings using GB-RAR: A Case Study of the WGC under Construction, China

2020 ◽  
Vol 10 (3) ◽  
pp. 808 ◽  
Author(s):  
Lv Zhou ◽  
Jiming Guo ◽  
Xuelin Wen ◽  
Jun Ma ◽  
Fei Yang ◽  
...  
Keyword(s):  
Wavelet Analysis ◽  
Dynamic Characteristics ◽  
Horizontal Displacement ◽  
Dynamic Monitoring ◽  
High Rise ◽  
The North ◽  
Study Results ◽  
Under Construction ◽  
East West

Accurate dynamic characteristics of super high-rise buildings serve as a guide in their construction and operation. Ground-based real aperture radar (GB-RAR) techniques have been applied in monitoring and analyzing the dynamic characteristics of different buildings, but only few studies have utilized them to derive the dynamic characteristics of super high-rise buildings, especially those higher than 400 m and under construction. In this study, we proposed a set of technical methods for monitoring and analyzing the dynamic characteristics of super high-rise buildings based on GB-RAR and wavelet analysis. A case study was conducted on the monitoring and analysis of the dynamic characteristics of the Wuhan Greenland Center (WGC) under construction (5–7 July 2017) with a 636 m design height. Displacement time series was accurately derived through GB-RAR and wavelet analysis, and the accuracy reached the submillimeter level. The maximum horizontal displacement amplitudes at the top of the building in the north–south and east–west directions were 18.84 and 15.94 mm, respectively. The roof displacement trajectory of the WGC was clearly identified. A certain negative correlation between the temperature and displacement changes at the roof of the building was identified. Study results demonstrate that the proposed method is effective for the dynamic monitoring and analysis of super high-rise buildings with noninvasive and nondestructive characteristics.

scholarly journals An Experimental Study on Mechanical Behavior of Parallel Joint Specimens under Compression Shear

2018 ◽  
Vol 2018 ◽  
pp. 1-12
Author(s):  
Fei Wang ◽  
Ping Cao ◽  
Yu Chen ◽  
Qing-peng Gao ◽  
Zhu Wang
Keyword(s):  
Shear Stress ◽  
Shear Strength ◽  
Failure Mode ◽  
Shear Failure ◽  
Strain Curve ◽  
Shear Loading ◽  
Plane Shear ◽  
Joint Spacing ◽  
Dip Angle ◽  
Joint Inclination

In order to investigate the influence of the joint on the failure mode, peak shear strength, and shear stress-strain curve of rock mass, the compression shear test loading on the parallel jointed specimens was carried out, and the acoustic emission system was used to monitor the loading process. The joint spacing and joint overlap were varied to alter the relative positions of parallel joints in geometry. Under compression-shear loading, the failure mode of the joint specimen can be classified into four types: coplanar shear failure, shear failure along the joint plane, shear failure along the shear stress plane, and similar integrity shear failure. The joint dip angle has a decisive effect on the failure mode of the specimen. The joint overlap affects the crack development of the specimen but does not change the failure mode of the specimen. The joint spacing can change the failure mode of the specimen. The shear strength of the specimen firstly increases and then decreases with the increase of the dip angle and reaches the maximum at 45°. The shear strength decreases with the increase of the joint overlap and increases with the increase of the joint spacing. The shear stress-displacement curves of different joint inclination samples have differences which mainly reflect in the postrupture stage. From monitoring results of the AE system, the variation regular of the AE count corresponds to the failure mode, and the peak value of the AE count decreases with the increase of joint overlap and increases with the increase of joint spacing.

Study on Stability of High Embankments on Rock Slope under Complicated Stress Conditions

2011 ◽  
Vol 368-373 ◽  
pp. 1642-1648
Author(s):  
Gui Ling Ding
Keyword(s):  
Finite Element ◽  
Slip Surface ◽  
Three Dimensional ◽  
Slope Instability ◽  
Instability Criterion ◽  
Two Dimensional ◽  
Study Results ◽  
Geological Conditions ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

Three-dimensional finite element analysis should be used in stability analysis of slope because it can overcome the short advantages of two-dimensional finite element and can simulate the complex topographic and geological conditions. Based on the large-scale triaxial shear test, the modified Duncan-Chang model is established. Based on strength reduction elasto-plastic finite element, stability of high fill embankment was studied with three-dimensional finite element method considering the complex terrain conditions. Study results suggest that plastic strain and displacement mutant of slip surface node can be a sign of slope instability as a whole. At the same time calculation of three-dimensional finite element also does not converge. Therefore, it can be slope instability criterion calculate whether the finite element static analysis converges or not. On the other hand, stability safety factor of high fill embankment under three-dimensional conditions is larger than that of two-dimensional conditions, which shows that boundary conditions of high fill embankment enhance its stability.

Adiabatic shear failure under biaxial dynamic compression/ shear loading

1994 ◽  
Vol 17 (2-3) ◽  
pp. 203-214 ◽  
Author(s):  
L.W. Meyer ◽  
E. Staskewitsch ◽  
A. Burblies
Keyword(s):  
Shear Failure ◽  
Dynamic Compression ◽  
Shear Loading ◽  
Adiabatic Shear

Study on Mechanism of Slope Instability with Weak Interlayer

2011 ◽  
Vol 71-78 ◽  
pp. 3615-3618 ◽  
Author(s):  
Yun Fei Wang ◽  
Fu Ping Zhong ◽  
Huai Bao Chu ◽  
Li Ping Wang
Keyword(s):  
Stress Field ◽  
Failure Mechanism ◽  
Shear Failure ◽  
Slope Instability ◽  
Tensile Failure ◽  
Cyclic Process ◽  
Research Subject ◽  
Geological Conditions ◽  
Weak Interlayer ◽  
Mass Rock

In the process of the highway building, especially in mountain region the some complex geological conditions often appears. In this paper, using the slope of highway with weak interlayer as the research subject, systematically analyzing the stress field and plastic field during the excavation of the slope, obtained the failure mechanism of the slope with weak interlayer, which is a cyclic process that weak interlayer shear failure led to the tensile failure of its upper mass rock. It has extraordinarily important guiding significance for the protection and reinforcement of similar slope.

scholarly journals Reliability assessment of the behavior of reinforced and/or prestressed concrete beams sections in shear failure

2021 ◽  
Vol 15 (57) ◽  
pp. 195-222
Author(s):  
Karim Benyahi ◽  
Mohand Said Kachi ◽  
Youcef Bouafia ◽  
Salma Barboura ◽  
Jia Li
Keyword(s):  
Prestressed Concrete ◽  
Shear Failure ◽  
Concrete Beams ◽  
Limit State ◽  
Shear Loading ◽  
The Real ◽  
Modeling Uncertainties ◽  
Reliability Method ◽  
Real Behavior ◽  
State Curve

The object of this article is to be able to simulate the behavior of reinforced and/or prestressed concrete beam’s section in the shear loading through a model allowing the evaluation of nonlinear strains caused by shear, while taking into account the real behavior of the materials. In this approach, we are often confronted with problems of modeling uncertainties linked to some insufficiencies of the mechanical model allowing to describe the physical phenomena in a realistic way. For that, it is necessary to use a reliability model making it possible to evaluate their probability of failure, by establishing failure curves according to the different transition zones of the limit state curve of the nonlinear behavior in the shear loading up to at section failure of reinforced and/or prestressed concrete beams. In this work, we also propose a coupling of the reliability method by response surface to carry out the reliability optimization on complex mechanical models, where the mechanical and reliability models developed have been implemented on the Fortran. This allows the estimation in an efficient way of the different reliability characteristics according to each transition zone from the limit state curve to the real behavior until failure in the shear loading.

scholarly journals Effectiveness of Adaptation Strategies among Coastal Communities in Ghana: The Case of Dansoman in the Greater Accra Region

2019 ◽  
pp. 1-12
Author(s):  
Isaac Sarfo ◽  
Otchwemah Henry Bortey ◽  
Terney Pradeep Kumara
Keyword(s):  
Climate Change ◽  
Climate Change Adaptation ◽  
Large Scale ◽  
Global Climate ◽  
Evaluation Process ◽  
Monitoring And Evaluation ◽  
Adaptation Strategies ◽  
Study Results ◽  
Evaluation And Monitoring ◽  
Climate Change Adaptation Strategies

Global climate action plans risk resulting to climate maladaptation and shocks when prudent measures are inapt. Adaptation strategies require multidisciplinary approach from all sectors with periodic monitoring and evaluation which are carefully planned, locally adaptable and results-oriented. For decades, various governments, development practitioners and international organizations have made concerted efforts in tackling large scale climate events. These stern initiatives forms part of Millennium Sustainable Development Goals (SDGs), specifically SDG 13 meant to combat climate change. The increasing demand for frameworks that effectively monitor and examine the outcomes of these huge investments made by policy-makers across regions have enhanced the evaluation and monitoring of various climate change adaptation strategies. This study sought to assess the effectiveness and sustainability of initiated adaptation strategies. The study used descriptive statistics based on informants’ knowledge and experience to assess the effectiveness of adaptation strategies in Dansoman and compare the results with the case of Nador-Berkane coastal community in north eastern part of Morocco where the “no-regret strategy” concept was adopted. Assessing the effectiveness of strategies is one of the key components of monitoring and evaluation process of climate change and is often overlooked, hence, the need for this study. Results from this study based on the informants’ experience and assessment show that climate change adaptation strategies in the study area are not effective and sustainable. This study serves as a baseline information for relevant stakeholders on critical areas, which ought to be prioritized to reduce the locals’ vulnerability to climate hazards. Assessing the effectiveness of adaptation strategies aid in ensuring efficiency and efficacy of planned and already initiated projects. Further research could be conducted on the cost of adaptation mechanisms and willingness to pay for sea defense systems in the area.

scholarly journals Gender differences of response to various options of drug therapy in patients with chronic heart failure after suffered myocardial infarction

2016 ◽  
Vol 97 (1) ◽  
pp. 17-25
Author(s):  
G M Dadashova
Keyword(s):  
Myocardial Infarction ◽  
Heart Failure ◽  
Chronic Heart Failure ◽  
Clinical Status ◽  
Left Ventricular ◽  
Dynamic Monitoring ◽  
Aldosterone Antagonists ◽  
Men And Women ◽  
The Third ◽  
Study Results

Aim. To evaluate gender features of treatment in patients with chronic heart failure who suffered myocardial infarction, determine the effect of angiotensin-converting enzyme inhibitors and angiotensin receptor blockers II, as well as antidepressants in the clinico-functional and psycho-emotional status, morphological and functional parameters of the heart in the treatment of men and women with this pathology.Methods. The study included 205 men and 185 women with chronic heart failure after suffering a myocardial infarction. Patients were randomized into three groups. Patients of the first group (80 men and 70 women) received background treatment (cardiac glycosides, diuretics, aldosterone antagonists, prolonged nitrates if necessary, acetylsalicylic acid, atorvastatin and perindopril 5-10 mg/day. The patients of the second group (80 men and 70 women) received valsartan 80-160 mg/day in addition to the above-noted background treatment. In the therapeutic regimen of the third group of patients (45 men and 45 women) sertraline in a dose of 50 mg/day was included in addition to background treatment. All the patients underwent usual methods of general clinical examination, the 6-minute walk test, clinical status evaluation, the anxiety syndrome severity assessment using a Hamilton scale, echocardiography. The patients dynamic monitoring was carried out for 6 months.Results. The study results showed that provided therapy has comparable clinical effect in both men and women in all three groups. Statistically significant improvement in clinical condition indicators was reported and as a result, exercise tolerance increased. At the same time the quality of life improvement was more pronounced (p <0.001) in patients of the third group, amid the perindopril and sertraline use. According to the results of our study in patients of all three groups provided therapy has a comparable positive effect on echocardiography indicators, including those which characterize left ventricular hypertrophy.Conclusion. Amid the provided treatment in all three groups positive dynamics of clinical status indicators and intracardiac dynamics was reported; in addition to that the dynamics of both clinical status and linear and volumetric heart parameters was more pronounced amid the treatment with perindopril in combination with sertraline.

scholarly journals Numerical analysis of the precursory information of slope instability process with constant resistance bolt

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Feng Chen ◽  
Xue-bin Wang ◽  
Yan-hong Du ◽  
Chun-an Tang
Keyword(s):  
Principal Stress ◽  
Shear Failure ◽  
Lateral Displacement ◽  
Numerical Test ◽  
Significant Rise ◽  
Slope Instability ◽  
Practical Significance ◽  
Landslide Monitoring ◽  
Monitoring Method ◽  
Constant Resistance

AbstractThe instability of slope has already threatened life and property safety of the people, and improving the monitoring method of slope stability has important theoretical and practical significance for disaster prevention and reduction. According to the idea of “Newton force sudden drop and catastrophic occurrence” proposed by M.C. He in the landslide monitoring, a numerical model with constant resistance bolt has been established. Through numerical simulation research, it is found that the maximum principal stress, minimum principal stress and shear stress of the intersection point P of landslide surface and constant resistance bolt are sudden growth and sudden decrease, the vertical displacement and lateral displacement of this point P appear rise and fall before three kinds of stress. When loading to the next step of the step where three stress have reduced to a minimum value the slope is unstable and destroyed. At this time, the constant resistance bolt has undergone larger plastic deformation and damaged. Finally, comparing the stress curves and the acoustic emission (AE) curves, it can be seen that stress decreases from the maximum value and the AE curves begin to show a significant rise, the two curves display opposite law. It can be seen from the AE diagram that the failure mode of the slope is a combined tension and shear failure. The numerical test results provide a new idea for real-time monitoring and forecasting of slope.

Comparative study of two types of self-recovery shape-memory alloy pseudo-rubber isolator devices under compression–shear interactions

2019 ◽  
Vol 30 (15) ◽  
pp. 2241-2256 ◽  
Author(s):  
Suchao Li ◽  
Chenxi Mao
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Shear Failure ◽  
Three Dimensional ◽  
Residual Deformation ◽  
Shear Loading ◽  
Wire Mesh ◽  
Type I ◽  
Rubber Isolator ◽  
Deformation Recovery

Two types of novel shape-memory alloy-based devices with three-dimensional isolation potential and deformation recovery abilities were developed. These two types of isolators, which are called shape-memory alloy pseudo-rubber isolators, were both created with martensitic shape-memory alloy wires through weaving, rolling, and punching processes, but they underwent heat treatment at different fabrication stages and for different durations. A series of mechanical tests were performed on these two types of shape-memory alloy pseudo-rubber isolators to investigate their properties under compression, shear, and combined compression–shear loading at room temperature. The restorable shear limit was then investigated, and the corresponding shear failure mechanism was discussed according to a tension test of one thin layer of the shape-memory alloy wire mesh. Subsequently, the deformation recovery ability of the shape-memory alloy pseudo-rubber isolator with residual deformation was tested through heating on a thermo-control stove. Finally, the mechanical-property stabilities, energy-dissipation abilities, and recovery abilities were compared between the two types of shape-memory alloy pseudo-rubber isolator devices. The experimental results indicated that both types of shape-memory alloy pseudo-rubber isolators had excellent residual deformation recovery abilities, and the type-I shape-memory alloy pseudo-rubber isolator device had more stable mechanical properties than the type-II shape-memory alloy pseudo-rubber isolator. The type-I shape-memory alloy pseudo-rubber isolator device is thus an ideal candidate for traditional three-dimensional isolators.

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