scholarly journals STUDY ON SURFACE STABILITY AND RESIDUAL DEFORMATION OF OLD GOAF IN DONGJIAGOU MINE，CHINA

2021 ◽  
Vol 30 (1) ◽  
Author(s):  
Zechuang Li ◽  
Peifeng Cheng ◽  
Zhibin Liu ◽  
Junjie Zheng
Keyword(s):  
Residual Deformation ◽  
Bridge Engineering ◽  
Overburden Rock ◽  
Influence Zone ◽  
Surface Stability ◽  
Analysis And Evaluation ◽  
Predicted Model ◽  
The Stability ◽  
Ground Stability ◽  
Poor Stability

Old goaf under the overpass becomes serious hidden trouble of subgrade-pavement and bridge engineering. Based on geological survey, geophysical survey and theoretical analysis, this paper studies on formation mechanism and distribution characteristics of the surface residual deformation in old goaf in No.9 Line Overpass across Rapid Rail Transit Line No.3 in Dalian city. A comprehensive analysis and evaluation has been made on the stability of old goaf. Based on the calculation principle of the probability integration method, the conception of ground residual subsidence coefficient and the predicted model of residual deformation are proposed, ground residual deformation of old goaf under the overpass is predicted. According to the zonal principles of ground stability, the stabilities of areas are divided. The results indicated that, new overpass has an important effect on the old goaf overburden rock activation in study area that the surface will be instability uneven settlement and the ground residual deformation values will exceed allowable values. Some treatment should be done to the old goaf because of the poor stability of goaf and non-goaf within influence zone in study area.

Sensitivity Analysis and Numerical Stability Analysis of the Algorithms for Predicting the Performance of Turbines

2014 ◽  
Vol 136 (9) ◽  
Author(s):  
Ming Wei ◽  
Yonghong Wang ◽  
Huafen Song
Keyword(s):  
Numerical Stability ◽  
Rounding Error ◽  
One Dimensional ◽  
Flow Models ◽  
Numerical Stability Analysis ◽  
Last Stage ◽  
The Stability ◽  
Performance Calculation ◽  
Poor Stability ◽  
Input Error

Sensitivity and numerical stability of an algorithm are two of the most important criteria to evaluate its performance. For all published turbine flow models, except Wang method, can be named the “top-down” method (TDM) in which the performance of turbines is calculated from the first stage to the last stage row by row; only Wang method originally proposed by Yonghong Wang can be named the “bottom-up” method (BUM) in which the performance of turbines is calculated from the last stage to the first stage row by row. To find the reason why the stability of the two methods is of great difference, the Wang flow model is researched. The model readily applies to TDM and BUM. How the stability of the two algorithms affected by input error and rounding error is analyzed, the error propagation and distribution in the two methods are obtained. In order to explain the problem more intuitively, the stability of the two methods is described by geometrical ideas. To compare with the known data, the performance of a particular type of turbine is calculated through a series of procedures based on the two algorithms. The results are as follows. The more the calculating point approaches the critical point, the poorer the stability of TDM is. The poor stability can even cause failure in the calculation of TDM. However, BUM has not only good stability but also high accuracy. The result provides an accurate and reliable method (BUM) for estimating the performance of turbines, and it can apply to all one-dimensional performance calculation method for turbine.

scholarly journals Application of GPR and ERT methods for recognizing of gypsum deposits in urban areas

2019 ◽  
Vol 67 (6) ◽  
pp. 2015-2030
Author(s):  
Tomisław Gołębiowski ◽  
Elżbieta Jarosińska
Keyword(s):  
Urban Areas ◽  
Noninvasive Detection ◽  
Resistivity Tomography ◽  
Surface Stability ◽  
Fractured Bedrock ◽  
Geophysical Surveys ◽  
Standard Orientation ◽  
Underground Infrastructure ◽  
The Stability ◽  
Ground Penetrating

Abstract This paper presents the selected results of GPR (ground penetrating radar) and ERT (electrical resistivity tomography) surveys carried out on the sites in Poland where shallow karst forms were found in gypsum deposits. The aim of the surveys was the noninvasive detection of karst forms as well as weathered and fractured bedrock which may threaten the stability of the surface and, consequently, may cause damage to buildings, as well as overground and underground infrastructure. The geophysical surveys were conducted at a depth of only a few meters, i.e., to the depth of buildings foundations. GPR surveys were carried out in short-offset reflection profiling mode with standard orientation of the antennae set; however, on one site, different orientations of antennae were tested. During ERT surveys, different measurement arrays were applied in order to analyze which array was optimal for the detection of karst forms as well as weathered and fractured bedrock. Complex interpretation of geophysical surveys resulted in reduced ambiguity and revealed some regions, dangerous for surface stability. Due to the fact that gypsum deposits were investigated to the depth of maximum 10 m; therefore, hydrological processes were analyzed in the paper instead of hydrogeological processes.

Overburden Rock Stability Analysis of Shallow Tunnel

2011 ◽  
Vol 105-107 ◽  
pp. 1304-1307
Author(s):  
Yun Long Wang ◽  
Zhong Sheng Tan
Keyword(s):  
Jiaozhou Bay ◽  
Decisive Role ◽  
Overburden Rock ◽  
Safety Factors ◽  
Tunnel Stability ◽  
Rock Stability ◽  
Subsea Tunnel ◽  
The Stability ◽  
The Moment ◽  
Elastic Foundation Beam

As for shallow tunnels through the rock layers, the stability of the overburden rock has a decisive role on the tunnel stability; furthermore, analyzing the stability of the overburden rock is very important to the supporting design and the choice of excavation method. Method of elastic foundation beam is used to research the moment of overburden rock, and the formula of overburden rock stable thickness is finished. Seven sections of JIAOZHOU Bay Subsea Tunnel are took for example to analyze the safety factor of different span and overburden rock thickness, then the stability of overburden rock is analyzed. The results show that the overburden rock safety factors of these seven sections of JIAOZHOU Bay Subsea Tunnel are range from 0.65 to 0.85. Compared with the experimental results, theoretical analysis of the results are more consistent The actual example verifies that the overburden rock stability in this paper is feasible.

A Buoyancy and Stability Mechanism for Underwater Vehicles

2000 ◽  
Vol 34 (2) ◽  
pp. 22-25
Author(s):  
Manikoth Aravindakshan
Keyword(s):  
Underwater Vehicles ◽  
Design Parameters ◽  
Vehicle Design ◽  
Hydraulic Power ◽  
Water Seepage ◽  
The Stability ◽  
Negative Buoyancy ◽  
Activation Depth ◽  
Poor Stability

This paper describes the design of a simple, inexpensive but effective ‘detach weight’ device that can aid in the stability as well as the recovery of underwater vehicles and unpropelled consoles. If the vehicle attempts to cross the maximum specified sea depth due to water seepage, poor stability, failure of normal recovery schedule, or inherent negative buoyancy as that of a console, then the proposed mechanism gets activated to achieve terminal buoyancy. Non-reliance on electrical, pneumatic or hydraulic power and sensors distinguish the device from conventional ballasting methods. Insitu assembly and adjustments of activation depth and weight can add flexibility to the vehicle design parameters such as overall CG, weight, trim, list etc.

Recent Progress in Black Phosphorus Sensors

2020 ◽  
Vol 16 (7) ◽  
pp. 1045-1064
Author(s):  
Tingting Ma ◽  
Hao Huang ◽  
Wenfei Guo ◽  
Chuanxiang Zhang ◽  
Zhu Chen ◽  
...  
Keyword(s):  
Carrier Mobility ◽  
Electrochemical Sensors ◽  
Black Phosphorus ◽  
Synthesis Methods ◽  
Tunable Bandgap ◽  
High Carrier Mobility ◽  
High Carrier ◽  
The Stability ◽  
New Sensors ◽  
Poor Stability

Black phosphorus (BP) is a new two-dimensional material with many unique properties, such as great biocompatibility, excellent surface activity, high carrier mobility, and tunable bandgap. Black phosphorus has been particularly attractive in sensor. However, black phosphorus isolated by traditional methods is easily oxidized and degraded by air, with poor stability, which limits its application as sensors. The modification and functionalization of black phosphorus enhance the stability, sensitivity, selectivity and biocompatibility of its application in sensor. This review describes recent progresses in sensor based on black phosphorus (2016–2020). Firstly, the structure and properties, synthesis methods, modification and functionalization of black phosphorus are briefly described. Then, the advancements in designing of various sensors based on black phosphorus are systematically provided, with a specific focus on electrochemical sensors, electrochemiluminescence sensors and photoelectrochemical sensors. Finally, latest challenges and further opportunities for developing new sensors with black phosphorus nanomaterial are discussed.

Analysis of the Stability of Current Mode PWM DC/DC Converter

2011 ◽  
Vol 143-144 ◽  
pp. 809-814
Author(s):  
Xiao Qiang Jia
Keyword(s):  
Duty Cycle ◽  
Current Mode ◽  
Compensation Circuit ◽  
The Poor ◽  
Slope Compensation ◽  
The Stability ◽  
Poor Stability

To address the poor Stability of current mode PWM DC / DC converter when duty cycle [5] is greater than 50%, by analyzing the converter, the design.of appropriate slope compensation circuit is given. And by Comparing the experimental waveform through simulation, it can effectively solve the converter poor stability and interference.of noise, if the slope compensation is appropriate.

On the surface stability of liquid conductors in electromagnetic shaping

1995 ◽  
Vol 302 ◽  
pp. 1-28 ◽  
Author(s):  
Thomas P. Felici
Keyword(s):  
Circular Cross Section ◽  
Energy Functional ◽  
Exact Nature ◽  
Surface Stability ◽  
Metal Shield ◽  
High Frequency Electromagnetic Field ◽  
The Stability ◽  
The Second Variation ◽  
Electromagnetic Shaping ◽  
The Magnetic Field

In a process involving electromagnetic shaping, a high-frequency electromagnetic field is used to deform a liquid conductor into a required shape. This is particularly relevant to processes such as levitation melting. In this paper the stability of such configurations are investigated. The second variation of an appropriate energy functional is derived whose minimum states correspond to stable configurations, thus providing a stability criterion. As an example, this is applied to the shaping of a levitated cylinder of circular cross-section and to an almost spherical axisymmetric shape. In both cases we find that these shapes are unstable. We then consider enclosing the entire shaping device in a metal shield, thus preventing the escape of the magnetic field. It is then shown that in general the shield has a stabilizing effect, whose exact nature depends on the topology of the liquid shape and on the field structure on its surface. This differing behaviour is discussed for two-dimensional spherical and toroidal shapes.

Flight Dynamic Characteristic Analysis of a Generic Airbreathing Hypersonic Vehicle

2014 ◽  
Vol 716-717 ◽  
pp. 724-729 ◽  
Author(s):  
Rui Guang Yang ◽  
Jian Qiao Yu ◽  
Yuan Chuan Shen
Keyword(s):  
Dynamic Characteristic ◽  
High Speed ◽  
Complex Dynamics ◽  
Equations Of Motion ◽  
Hypersonic Vehicle ◽  
Propulsion System ◽  
Characteristic Analysis ◽  
The Stability ◽  
Dynamics Characteristic ◽  
Poor Stability

Because of the high speed, strong coupling between aerodynamics and propulsion system, complex environmental conditions and new propulsion system, the airbreathing hypersonic vehicles have a complex dynamics characteristic. This paper use the generic hypersonic vehicle model (CSULA-GHV) to research this issue. The nonlinear longitudinal equations of motion are linearized based on the assumption of little perturbation. Analyze the dynamic characteristic on a feature point selected. The results show that, the stability of this model is poor. It has to design an efficient controller to adjust the poor stability.

The Stability and Management of “Sandwich” Type Slopes in Extrusive Rock Area

2012 ◽  
Vol 472-475 ◽  
pp. 1253-1256
Author(s):  
Hong Wei ◽  
Hong Wang
Keyword(s):  
Hainan Island ◽  
Soil Layers ◽  
Loose Soil ◽  
Late Tertiary ◽  
Sandwich Type ◽  
Extrusive Rock ◽  
Management Method ◽  
The Stability ◽  
Faulted Zone ◽  
Poor Stability

Northern area of Hainan Island is located in the south of Leiqiong faulted zone; new tectonic movement and volcanic activity have intense since late tertiary. Cenozoic volcano in the region is developed, various types of extrusive rocks widely distributed which often directly cumulate on the Cenozoic sedimentary soil layers, then covered by more loose soil, form a soft - hard - soft “sandwich” type slope with a poor stability. Based on the study of this slope and simulate its stability, this paper proposed this kind of slope's destruction mechanism as well as the management method

Sign in / Sign up

Export Citation Format

Share Document