scholarly journals Roof Subsidence and Movement Law of Composite Strata Mining: Insights from Physical and Numerical Modeling

Minerals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 3
Author(s):  
Yongqian Wang ◽  
Xuan Wang ◽  
Jiasheng Zhang ◽  
Xiaobin Chen ◽  
Wujun Zhu ◽  
...  
Keyword(s):  
Numerical Model ◽  
Physical Model ◽  
Surface Subsidence ◽  
Similarity Criteria ◽  
Theoretical Formula ◽  
Constant Field ◽  
Rock Formations ◽  
Movement Characteristics ◽  
Similar Materials ◽  
Dip Angle

Sinking and horizontal movements are necessary parameters for assessing the potential impacts of surface subsidence in mining activities. Based on similarity criteria, the surface subsidence mechanism was studied using a physical model composed of similar materials such as sand, cement, and gypsum. With constant field geological parameters maintained in two angles of a coal seam, models of roof subsidence of composite rock were compared for different mining configurations. In accordance with observations from the physical model, it was concluded that subsidence and horizontal movement of strata near to and far from the coal seams were different and divided into five zones. The zone above a mined-out area underwent greater total subsidence compared to unexploited regions on both sides. Correlations between a subsidence curve and the height of a caving zone and the mining dip angle were obtained and verified from numerical model results. According to the roof’s position relative to the goaf, the area above the goaf of the composite rock layer was divided into three regions: a curving zone, a water-conducting fracture zone, and a falling zone, to which the subsidence and movement characteristics of each area could be proposed. Compared with the subsidence and movement characteristics observed from the physical and numerical model, the acquisition of subsidence characteristics and parameters in different areas can provide an idea for improvement, innovation or proposal of a theoretical formula for subsidence prediction of composite rock formations.

Study on Impact of Vibration Direction on Linear Vibration Screening Effect

2012 ◽  
Vol 226-228 ◽  
pp. 186-190
Author(s):  
Yue Min Zhao ◽  
Ke Wang ◽  
Liang Dong ◽  
Bo Zhang ◽  
Xu Liang Yang ◽  
...  
Keyword(s):  
Sieve Plate ◽  
Test Results ◽  
Simulation Test ◽  
Screening Process ◽  
Vibration Direction ◽  
Screening Effect ◽  
Direction Angle ◽  
Movement Characteristics ◽  
Screening Efficiency ◽  
Dip Angle

Based on Hertz-Mindlin contact model in software EDEM by discrete element method, using linear vibrating screen 360 mm×600 mm, movement characteristics of particle group on sieve plate and law of particles going through sieve plate were studied in screening process of coal in certain conditions, which were as follows: dip angle was 0 °, amplitude was 5 mm, frequency was 11 Hz. The simulation test results show that there are important influences of vibration direction on screening process. And influence law of vibration direction on screening effect was revealed finally. The paper also gained mathematical model between particle group’s screening efficiency and vibration direction angle, and mathematical models of particles easy or hard to sieve and material between average movement speeds and vibration direction angle.

Model Test Study on Influences of Layered Rock Mass Dip Angle on Stability of Deep-Buried Tunnel

2011 ◽  
Vol 90-93 ◽  
pp. 2363-2371
Author(s):  
Bin Wei Xia ◽  
Ke Hu ◽  
Yi Yu Lu ◽  
Dan Li ◽  
Zu Yong Zhou
Keyword(s):  
Rock Mass ◽  
Physical Model ◽  
Model Test ◽  
Physical Models ◽  
Physical Model Test ◽  
Stress Distributions ◽  
Failure Characteristics ◽  
Layered Rock ◽  
Layered Rock Mass ◽  
Dip Angle

Physical models of layered rock mass with different dip angles are built by physical model test in accordance with the bias failure characteristics of surrounding rocks of layered rock mass in Gonghe Tunnel. Bias failure characteristics of surrounding rocks in thin-layered rock mass and influences of layered rock mass dip angle on stability of tunnel are studied. The research results show that failure characteristics of physical models generally coincide with those of surrounding rocks monitored from the tunnel site. The failure regions of surrounding rock perpendicular to the stratification planes are obviously larger than those parallel to. The stress distributions and failure characteristics in the surrounding rocks are similar to each physical model of different dip angles. The stress distributions and failure regions are all elliptic in shape, in which the major axis is in the direction perpendicular to the stratification planes while the minor axis is parallel to them. As a result, obvious bias failure of surrounding rocks has gradually formed. The physical model tests provide reliable basis for theoretical analysis on the failure mechanism of deep-buried layered rock mass.

scholarly journals Effects of Water Intake Layout along the Wharf Shoreline on Ships

2019 ◽  
Vol 26 (4) ◽  
pp. 165-171
Author(s):  
Xian-wei Kong ◽  
Lei Ding ◽  
Hai-cheng Liu ◽  
Jing Qu ◽  
Xiao-song Li
Keyword(s):  
Numerical Model ◽  
Water Level ◽  
Physical Model ◽  
Water Intake ◽  
Hydrodynamic Forces ◽  
Lateral Flow ◽  
Real Situation ◽  
The Real ◽  
Level Difference ◽  
Two Sides

Abstract The construction of a water intake along the wharf shoreline can realise the intensive and comprehensive utilisation of the shoreline. However, since the water intake will increase the lateral flow at the wharf and also the hydrodynamic forces on ships, it will bring risks to ships mooring and leaving. The effects of the water intake on ships are studied using a physical model, numerical model and standard formulas. The results show that it leads to an increase of the hydrodynamic forces acting on the ship when the standard formulas are used to calculate the forces without considering the water level difference between the two sides of the ship. The results of the physical model are closer to the real situation. Measures that can effectively reduce the influence of the water intake on ships are proposed by increasing the distance between the wharf front and the front of the water intake as well as the depth of the water inlet windows.

scholarly journals Key Parameters of Roof Cutting of Gob-Side Entry Retaining in a Deep Inclined Thick Coal Seam with Hard Roof

Energies ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 934 ◽  
Author(s):  
Jinzhu Hu ◽  
Manchao He ◽  
Jiong Wang ◽  
Zimin Ma ◽  
Yajun Wang ◽  
...  
Keyword(s):  
Numerical Model ◽  
Coal Seam ◽  
Economic Benefits ◽  
Surrounding Rock ◽  
Thick Coal Seam ◽  
Hard Roof ◽  
Coal Recovery ◽  
Rock Structure ◽  
Different Depths ◽  
Dip Angle

Gob-side entry retaining by roof cutting (GERRC) employed in a deep inclined thick coal seam (DITCS) can not only increase economic benefits and coal recovery, but also optimize surrounding rock structure. In accordance with the principles of GERRC, the technology of GERRC in DITCS is introduced and a roof-cutting mechanical model of GERRC is proposed to determine the key parameters of the depth and angle of RC. The results show that the greater the RC angle, the easier the caving of the goaf roof, but the length of cantilever beam increases. The depth of RC should account for the dip angle of the coal seam when the angle is above 20°. Increasing the coal seam dip angle could reduce the volume of rock falling of the goaf roof, but increase the filling height of the upper gangue to slide down. According to numerical model analysis of the stress and displacement of surrounding rock at different depths and angles of RC, when the depth of RC increased from 9 m to 13 m, the distance between the stress concentration zone and the coal side is increased. When the angle of RC increased from 0° to 20°, the value of roof separation is decreased. GERRC was applied in a DITCS with 11 m depth and 20° RC angle, and the field-measured data verified the conclusions of the numerical model.

scholarly journals Surface Subsidence Prediction Method for Coal Mines with Ultrathick and Hard Stratum

2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Hongkai Han ◽  
Jialin Xu ◽  
Xiaozhen Wang ◽  
Jianlin Xie ◽  
Yantuan Xing
Keyword(s):  
Coal Mining ◽  
Coal Mine ◽  
Prediction Method ◽  
Prediction Equation ◽  
Arbitrary Cross Section ◽  
Surface Subsidence ◽  
Strong Impact ◽  
Subsidence Prediction ◽  
Movement Characteristics ◽  
Mining Condition

Overburden conditions consisting of ultrathick and hard stratum (UTHS) are widespread in China and other countries, but existing surface subsidence prediction methods ignore the strong impact of UTHS on surface subsidence. They are thus not applicable for surface subsidence prediction for coal mining with the presence of UTHS. We conducted actual measurements of surface and UTHS subsidence in the Tingnan Coal Mine. The results showed that under the UTHS mining condition, the required gob dimension is much larger than the empirical value when the surface reaches sufficient mining and that the actual measured maximum value of surface subsidence is much smaller than the empirical value. The UTHS subsidence is approximately equal to the surface subsidence. The movement of UTHS has a strong impact on surface subsidence and has a controlling function for it. It was proposed that surface subsidence could be approximately predicted by calculating the UTHS subsidence. The UTHS movement characteristics were studied using Winkler’s theory of beams on an elastic foundation, the subsidence prediction equation of the main sections in the strike and dip directions was obtained under different mining dimensions, and the subsidence prediction equation of any arbitrary cross section parallel to the two main sections was established. Then, the surface subsidence prediction method for coal mining with the presence of UTHS was developed, and the influences of UTHS thickness, strength, and layer position on the surface subsidence were discussed. The Tingnan Coal Mine was taken as an example, and the subsidence curves of the strike and dip main sections were calculated using different mining dimensions. Subsequently, the surface subsidence after the mining of working faces 204, 205, 206, and 207, respectively, was predicted, and the prediction method was verified by comparing the results with the measured surface subsidence results of working faces 204, 205, and 206.

Simulation of Angular Flow in a Shallow Basin Triggered by a Rotating Vertical Cylinder by SPH Method

2018 ◽  
Vol 881 ◽  
pp. 15-22
Author(s):  
Warniyati ◽  
Radianta Triatmadja ◽  
Nur Yuwono
Keyword(s):  
Numerical Model ◽  
Physical Model ◽  
Time Integration ◽  
Vertical Cylinder ◽  
Shear Velocity ◽  
Future Research ◽  
Sph Method ◽  
Virtual Particle ◽  
Real Particle ◽  
Particle Hydrodynamics

A simple numerical model has been generated for developing a code of Smoothed Particle Hydrodynamics (SPH) method. Those will be modified and used for future research. In this computational research domain is a square that consists of a real particle and virtual particle as the boundary treatment. In the initial condition, particle occupies a certain position. Circular flow has been generated by a rotating vertical cylinder to produce shear velocity to the real particle. The particles movement has been observed during time integration. A physical model has been constructed to compare the numerical model. The movement of real particles on the numerical model agrees with the movement of water particles on the physical model.

scholarly journals Groundwater Flow Modeling in Karst Aquifers: Coupling 3D Matrix and 1D Conduit Flow via Control Volume Isogeometric Analysis—Experimental Verification with a 3D Physical Model

Water ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 1787 ◽  
Author(s):  
Luka Malenica ◽  
Hrvoje Gotovac ◽  
Grgo Kamber ◽  
Srdjan Simunovic ◽  
Srikanth Allu ◽  
...  
Keyword(s):  
Free Surface ◽  
Numerical Model ◽  
Groundwater Flow ◽  
Physical Model ◽  
Isogeometric Analysis ◽  
Numerical Solutions ◽  
Control Volume ◽  
Karst Aquifers ◽  
Conduit Flow ◽  
Laboratory Conditions

A novel numerical model for groundwater flow in karst aquifers is presented. A discrete-continuum (hybrid) approach, in which a three-dimensional matrix flow is coupled with a one-dimensional conduit flow, was used. The laminar flow in the karst matrix is described by a variably saturated flow equation to account for important hydrodynamic effects in both the saturated and unsaturated zones. Turbulent conduit flow for both free surface and pressurized flow conditions was captured via the noninertia wave equation, whereas the coupling of two flow domains was established through an exchange term proportional to head differences. The novel numerical approach based on Fup basis functions and control-volume formulation enabled us to obtain smooth and locally conservative numerical solutions. Due to its similarity to the isogeometric analysis concept (IGA), we labeled it as control-volume isogeometric analysis (CV-IGA). Since realistic verification of the karst flow models is an extremely difficult task, the particular contribution of this work is the construction of a specially designed 3D physical model ( dimensions: 5.66 × 2.95 × 2.00 m) in order to verify the developed numerical model under controlled laboratory conditions. Heterogeneous porous material was used to simulate the karst matrix, and perforated pipes were used as karst conduits. The model was able to capture many flow characteristics, such as the interaction between the matrix and conduit, rainfall infiltration through the unsaturated zone, direct recharge through sinkholes, and both free surface and pressurized flow in conduits. Two different flow experiments are presented, and comparison with numerical results confirmed the validity of the developed karst flow model under complex laboratory conditions.

Analysis of Effect Factors about the Ground Settlement during Foundation Pit Excavation

2014 ◽  
Vol 1065-1069 ◽  
pp. 7-10
Author(s):  
Fei Fei Liang ◽  
Ren Wang Liang ◽  
Xing Hua Xiang
Keyword(s):  
Numerical Model ◽  
Surface Subsidence ◽  
Ground Settlement ◽  
Effect Factors ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Deep Foundation Pit ◽  
Adjacent Buildings ◽  
Negative Effect

The excavation usually cause the settlement of surrounding soils, which will have a negative effect on the adjacent buildings. To find the effective measures to reduce the surface subsidence,a numerical model which is based on a project example is developed in this paper to analyze the settlement of surrounding soils during the excavation of a deep foundation pit by using FLAC3D.The influence of excavation on settlement outside the foundation pit is investigated when changing one of the factors which include reinjection pressures、waterproof curtain. The results show that: (1) The settlement of surrounding soils decreases gradually with the increase of reinjection pressures. Moreover ,the settlement with reinjection are around two times the value without reinjection.(2) The settlement of surrounding soils decreases gradually with the curtain depth increases. In the actual projects,we can decrease the settlement of surrounding soils by increasing the reinjection pressures and curtain depth.

scholarly journals DETERMINATION OF WAVE CREST ELEVATIONS FOR SLAMMING FORCES ON JETTY WITH VERTICAL WALL END

2017 ◽  
pp. 7
Author(s):  
Esin Ozkan Cevik ◽  
Yalcin Yuksel ◽  
Burak Aydogan ◽  
Berna Ayat Aydogan ◽  
Tugce Yuksel
Keyword(s):  
Numerical Model ◽  
Physical Model ◽  
Wave Height ◽  
Vertical Wall ◽  
Wave Disturbance ◽  
Wave Crest ◽  
Shore Protection ◽  
Model Study ◽  
Vertical Walls

Wave disturbance study for a closed end jetty conducted both in laboratory and through a numerical model is presented in this study. Shore protection structures and the structures at the end of the piers are considered for the calculation of the wave disturbance map. The connection locations of the jetties have been designed as vertical walls. These vertical structures and armored waterfront structures would affect the wave behavior in the study area along jetty axis causing reflection of waves and therefore the wave height in front of the structures might increase. This study intends to clarify wave agitation problem by using a numerical model with the help of physical model study.

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