scholarly journals A calculation methodology of fault relative displacement used to study the mechanical characteristic of fault slip

2021 ◽  
Vol 18 (6) ◽  
pp. 920-942
Author(s):  
Hongwei Wang ◽  
Ruiming Shi ◽  
Daixin Deng ◽  
Fan Cui ◽  
Yaodong Jiang
Keyword(s):  
Relative Displacement ◽  
Fault Slip ◽  
Mine Safety ◽  
Rock Stratum ◽  
Relative Slip ◽  
Fault Surface ◽  
Calculation Methodology ◽  
Mining Face ◽  
Local Slip ◽  
Seam Mining

Abstract Fault slip caused by mining disturbance is a crucial issue that can pose considerable threats to the mine safety. This paper proposes a point-by-point integration calculated methodology of fault relative slip and studies fault instability behavior induced by coal seam mining. A physical model with the existence of a fault and an extra-thick rock stratum is constructed to simulate the fault movement and calculate relative slip using the methodology. The results indicate that the fault relative slip can be regarded as a dynamic evolution process from local slip to global slip on the fault surface. The movement of surrounding rock masses near the fault experiences three stages, including along vertical downward, parallel to the fault and then approximately perpendicular to the fault. There will be an undamaged zone in the extra-thick rock strata when the mining face is near the fault structure. The collapse and instability of this undamaged zone could induce a violent fault relative slip. In addition, the influence of dip angles on the fault relative slip is also discussed. A formula for risk of fault relative slip is further proposed by fitting the relative displacement curves with different fault dip angles.

Mechanical model for the calculation of stress distribution on fault surface during the underground coal seam mining

2021 ◽  
Vol 144 ◽  
pp. 104765
Author(s):  
Hongwei Wang ◽  
Ruiming Shi ◽  
Jiaqi Song ◽  
Zheng Tian ◽  
Daixin Deng ◽  
...  
Keyword(s):  
Stress Distribution ◽  
Coal Seam ◽  
Mechanical Model ◽  
Fault Surface ◽  
Seam Mining

A critical look at the Wallace-Bott hypothesis in fault-slip analysis

2013 ◽  
Vol 184 (4-5) ◽  
pp. 299-306 ◽  
Author(s):  
Richard J. Lisle
Keyword(s):  
Shear Stress ◽  
Maximum Shear Stress ◽  
Fault Slip ◽  
Shear Stresses ◽  
Homogeneous State ◽  
Slip Direction ◽  
Fault Surface ◽  
State Of Stress ◽  
Simultaneous Movement

AbstractThe assumption is widely made that slip on faults occurs in the direction of maximum resolved shear stress, an assumption known as the Wallace-Bott hypothesis. This assumption is used to theoretically predict slip directions from known in situ stresses, and also as the basis of palaeostress inversion from fault-slip data. This paper examines different situations in relation to the appropriateness of this assumption. Firstly, it is shown that the magnitude of the shear stress resolved within a plane is a function with a poorly defined maximum direction, so that shear stress values greater than 90% of the maximum occur within a wide angular range (± 26°) degrees. The situation of simultaneous movement on pairs of faults requires slip on each fault to be parallel to their mutual line of intersection. However, the resolved shear stresses arising from a homogeneous state of stress do not accord with such a slip arrangement except in the case of pairs of perpendicular faults. Where fault surfaces are non-planar, the directions of resolved shear stress in general give, according to the Wallace-Bott hypothesis, a set of slip directions of rigid fault blocks, which is generally kinematically incompatible. Finally, a simple model of a corrugated fault suggests that any anisotropy of the shear strength of the fault such as that arising from fault surface topography, can lead to a significant angular difference between the directions of maximum shear stress and the slip direction.These findings have relevance to the design of procedures used to estimate palaeostresses and the amount of data required for this type of analysis.

scholarly journals THEORETICAL-EXPERIMENTAL ASSESMENT OF BRAKING SISTEMS FOR INCLINED LIFTS ACCORDING TO EN 81:22-2014.

2016 ◽  
Author(s):  
Enrique Alcalá ◽  
Beatriz Valles Fernandez ◽  
Angel Luis Martin López
Keyword(s):  
Simulation Model ◽  
Relative Displacement ◽  
Dynamical Behaviour ◽  
Emergency Braking ◽  
Braking System ◽  
Calculation Methodology ◽  
Norm Series ◽  
Definition Of ◽  
Optimal Behaviour

The inclined lifts, in case of emergency braking, can experience high longitudinal decelerations that can lead to passengers’ collisions with lift walls and interior elements. In 2014 the CEN/TC10 WG1 published the part 22 of the norm series 81 with regard to the construction elements and installation of electrical lifts with inclined trajectory. This norm stablishes, amongst other requirements, the maximum and minimum deceleration levels in both longitudinal and vertical directions. Both requirements, in opposite senses and the definition of the braking system, do not cause design difficulties in case of high slopes, but in case of lifts with the slope under a certain level they can be needed, to guarantee the fulfilment of the norm, elements that allow and additional relative displacement between the braking system and the cabin. To define the performances and the optimal behaviour of these systems it has been defined a simulation model of the dynamical behaviour of the lift under the conditions of the norm tests. Additionally, in this work it is presented a calculation methodology to define the cabin allowable weight corridor, for each braking effort made by each safety gear model, and the simulations have been validated with the results of tests with different braking efforts, weights and lift slopes. The present work has been performed in cooperation with Thyssen Krupp Elevadores with the aim of improving the knowledge of the brake dynamics of inclined lifts.DOI: http://dx.doi.org/10.4995/CIT2016.2016.2173

scholarly journals A parallel electric field penetration technique for identifying hazardous water sources beneath coal seam mining face floors

2019 ◽  
Vol 16 (5) ◽  
pp. 950-961 ◽  
Author(s):  
Xiongwu Hu ◽  
Dangdang Meng ◽  
Bin Luo ◽  
Pingsong Zhang ◽  
Rongxin Wu
Keyword(s):  
Electric Field ◽  
Coal Seam ◽  
Physical Model ◽  
Water Sources ◽  
Model Parameters ◽  
Parallel Electric Field ◽  
Electric Field Penetration ◽  
Mining Face ◽  
Seam Mining ◽  
Field Penetration

Abstract In this work, a highly applicable multi-channel parallel electric field penetration technique is proposed to facilitate identification of hazardous water sources beneath coal seam mining face floors. The effects of various parameters on the characteristics of the apparent resistivity curves of a spherical model were analyzed through numerical simulation. It was determined that the proposed technique was sensitive to several model parameters (resistivity, size and spatial location). In addition, physical model experiments were also performed. Resistivity was determined from a three-dimensional inversion of the measurements. The results showed that the proposed technique was highly effective in determining the electrical characteristics and spatial distribution range of the anomalous bodies in the physical model. An engineering application of the proposed technique further demonstrated its effectiveness and reliability. The proposed technique can provide a basis for formulating water disaster prevention and control measures for mining faces.

Coal Seam Group Protection Layer Face Causes and Characteristics Analysis of Dynamic Phenomenon

2012 ◽  
Vol 550-553 ◽  
pp. 502-505
Author(s):  
Yong Jiang Zhang ◽  
Xian Zheng Meng ◽  
Zun Yu Xu
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Protective Layer ◽  
Test Area ◽  
Mine Safety ◽  
Dynamic Phenomenon ◽  
Geological Conditions ◽  
Characteristics Analysis ◽  
Safety Production ◽  
Mining Face

In Xinji Coal Mine under complicated geological conditions, regional faults. Experimental zone for near coal seam group mining(6-1,7-1,7-2,8 seam), The objective conditions with protective layer . The minefield of soft broken coal seam, Soft layered coal firmness coefficient f = 0.18. In the test area of 210601,210603 6-1seam protective layer mining face during the period, there were 8 abnormal gas dynamic phenomenon, To the coal mine safety production brought hidden trouble. On the basis of dynamic phenomenon occurring phenomenon, analysis of the dynamic phenomena, combined with the test area actual situation, summed up the6-1coal power causes, for guiding the 6-1safety mining and provide a theoretical basis, has important significance.

Study of a Major Mechanism for Self-Loosening of Bolted Joints

2006 ◽  
Author(s):  
Ziqin Wang ◽  
Yanyao Jiang
Keyword(s):  
Contact Pressure ◽  
Three Dimensional ◽  
Bending Moment ◽  
Tangential Direction ◽  
Relative Displacement ◽  
Bolted Joints ◽  
Major Mechanism ◽  
Fe Simulations ◽  
Local Slip ◽  
D Model

A recent three-dimensional (3-D) finite element (FE) investigation on self-loosening of bolted joints revealed that two major mechanisms were responsible for the second-stage (nut rotation) self-loosening of bolted joints. One of the mechanisms is the slip-stick contact of the thread surfaces under the combined contact pressure and reversed bending moment exerted from the reversed transverse loading. The current investigation is a detailed study of the slip-stick contact of the thread surfaces with models that mimic the bolt loading condition. The contact pressure and the reversed bending moment are obtained from an earlier simulation for an M12 bolt. The FE simulations indicate that, with the contact pressure on the thread surface of the bolt and nut, the alternating bending moment results in the gradual motion between the contact thread surfaces. A detailed look at the contact surfaces reveals that localized slip along the tangential direction occurs in part of the contact area and the accumulation of this local slip is responsible for the gradual relative motion between bolt and nut. The FE simulations also indicate that the amplitude of the bending moment greatly influences the relative displacement between the bolt and the nut. There exists a threshold below which local slip will not occur. Results from a two-dimensional (2-D) model are discussed and compared with those obtained from a 3-D model.

Transmission of SH Waves Through an Elastic Layer Between Two Solids With Frictional Contact Interfaces

1999 ◽  
Vol 66 (3) ◽  
pp. 729-737 ◽  
Author(s):  
Y.-S. Wang ◽  
G.-L. Yu
Keyword(s):  
Incident Wave ◽  
Recurrence Relations ◽  
Layered Medium ◽  
Frictional Contact ◽  
Mixed Boundary ◽  
Mixed Boundary Conditions ◽  
Sh Waves ◽  
Relative Slip ◽  
Interface Friction ◽  
Local Slip

The propagation of SH waves in a three-layered medium containing an interlayer between two semi-infinite solids with frictional contact interfaces is studied. The incident wave, which propagates through the layer from one half-space to another with subcritical angle, is assumed to be strong enough so that friction may be broken, and the local slip may take place at the interfaces. The mixed boundary conditions involving inequalities and unknown intervals lead to a set of recurrence relations. Special examples are given for the case of identical materials to illustrate the mathematical procedure to obtain final results. The interface tractions and relative slip velocities are presented. The interaction between the two interfaces is discussed. It is shown that the slip of the interface near the incident wave may restrain the slip of the interface far from the incident wave, while that the latter may facilitate the former. We also find the instability of the system for similar values of the two interface friction coefficients. Finally, the energy transmitted through the interlayer and dissipated by the friction of the two interfaces are examined.

scholarly journals Formation Mechanism and the Height of the Water-Conducting Fractured Zone Induced by Middle Deep Coal Seam Mining in a Sandy Region: A Case Study from the Xiaobaodang Coal Mine

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Xiaoshen Xie ◽  
Enke Hou ◽  
Shuangming Wang ◽  
Xueyang Sun ◽  
Pengfei Hou ◽  
...  
Keyword(s):  
Coal Seam ◽  
Formation Mechanism ◽  
Coal Mine ◽  
Field Measurements ◽  
Development Stage ◽  
Mine Safety ◽  
Maximum Height ◽  
Fractured Zone ◽  
Seam Mining

The height of the water-conducting fractured zone (WCFZ) is a basic parameter related to water protection in coal mines and is also crucial for aquifer protection and mine safety. In order to accurately detect the height and shape and reveal the formation mechanism of the WCFZ, which is caused by middle-deep coal seam mining in a sandy region, the 112201 coalface at the 1# coal mine of Xiaobaodang was taken as a case study. Filed measurements including fluid leakage, borehole TV, and similar simulation were adopted to analyze the regularity of the WCFZ in this area. The detection results of field measurements showed that the maximum height of the WCFZ was 177.07 m in a borehole near the open-off cut, and the ratio of the height of the water-conducting fractured zone divided by the mining thickness was 30.53. The WCFZ acquired an inward-convergent saddle shape, which was inclined to the goaf. The saddle bridge was located at the boundary of the goaf, and the saddle ridge was located at the center of the goaf. Also, through analyzing the results of similar simulations, we found that, in the process of mining, separation cracks and the beam structure were the main forms of overburden disturbance transmitting upward and ahead of mining, respectively. The main cause of the increase in height of the WCFZ was the connection of the separation cracks and vertical cracks caused by fractures of beam structures. The development of the WCFZ was divided into five stages: incubation stage, development stage, rapidly increasing stage, slowly increasing stage, and stable stage. Moreover, the duration of each stage was related to the lithology and mining technology. This research can provide significant theoretical insights for the prediction of the WCFZ, enabling the prevention of water hazards on mine roofs and assisting with water resources protection.

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