Numerical Simulation Study of Crack Development Induced by Transient Release of Excavation Load during Deep Underground Cavern

2014 ◽  
Vol 638-640 ◽  
pp. 851-857
Author(s):  
Yi Luo ◽  
Xin Ping Li
Keyword(s):  
Numerical Simulation ◽  
Pressure Coefficient ◽  
Side Wall ◽  
Simulation Method ◽  
Deformation And Failure ◽  
Underground Cavern ◽  
Surface Development ◽  
Calculation Results ◽  
Deep Underground ◽  
Structural Surface

The cracking and developing of structural surfaces is one of the main causes for surrounding rock mass large deformation and failure in deep underground cavern excavation. A numerical simulation method for discontinuous structural surface development is proposed based on the transient unloading of excavation load during underground cavern excavation. The program will automatically evaluate every substep in the dynamic calculation, and determine if the development stops and the cracking direction based on dynamic fracture mechanics. The penalty function is adopted to simulate the opening and sliding characteristic of structural surfaces. And the cracking path would be shown by iterative calculation. Results show that, the lateral pressure coefficient (LPC) is the main factor of cracking direction. When structural surface is shallow to the side wall, the crack would develop to the surface of the side wall. When it is deep enough into the side wall, the cracking might stop before it goes to the surface of the side wall. The accuracy of this simulation is verified by the comparison to relative laboratory tests.

scholarly journals Study of the Effect of Centrifugal Force on Rotor Blade Icing Process

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Zhengzhi Wang ◽  
Chunling Zhu
Keyword(s):  
Numerical Simulation ◽  
Centrifugal Force ◽  
Rotor Blade ◽  
Flow Direction ◽  
Three Dimensional ◽  
Simulation Method ◽  
Two Phase ◽  
Numerical Simulation Method ◽  
Calculation Results ◽  
Flow Field Characteristics

In view of the rotor icing problems, the influence of centrifugal force on rotor blade icing is investigated. A numerical simulation method of three-dimensional rotor blade icing is presented. Body-fitted grids around the rotor blade are generated using overlapping grid technology and rotor flow field characteristics are obtained by solving N-S equations. According to Eulerian two-phase flow, the droplet trajectories are calculated and droplet impingement characteristics are obtained. The mass and energy conservation equations of ice accretion model are established and a new calculation method of runback water mass based on shear stress and centrifugal force is proposed to simulate water flow and ice shape. The calculation results are compared with available experimental results in order to verify the correctness of the numerical simulation method. The influence of centrifugal force on rotor icing is calculated. The results show that the flow direction and distribution of liquid water on rotor surfaces change under the action of centrifugal force, which lead to the increasing of icing at the stagnation point and the decreasing of icing on both frozen limitations.

Numerical Simulation of Feeding Powder Laser Cladding Temperature Field Based on ANSYS

2013 ◽  
Vol 690-693 ◽  
pp. 3334-3337
Author(s):  
Cheng Fa Song ◽  
Ming Di Wang
Keyword(s):  
Numerical Simulation ◽  
Cooling Rate ◽  
Laser Cladding ◽  
Simulation Method ◽  
Conduction Model ◽  
Beam Position ◽  
Life And Death ◽  
Laser Cladding Process ◽  
Calculation Results ◽  
Cladding Layers

The numerical simulation method of LCRM Using Coaxial Inside-Beam Powder Feeding is put forward in this page. LCRM conduction model is established, the life and death unit to be used to simulate the real laser cladding process. Calculation results show that the molten pool temperature will gradually increase with the number of cladding layers increase; the highest temperature at the point of application of the laser beam position later; in the cladding process, cooling rate is great in high temperature period, and in low temperature section, cooling rate relatively slight.

scholarly journals Study on the Thermal Environment Inside a Fully-Enclosed Subway Noise Barrier

2020 ◽  
Vol 143 ◽  
pp. 01044
Author(s):  
Lei Liu ◽  
Lianghan Zhang ◽  
Zhongxu Kang ◽  
Kun Yao
Keyword(s):  
Numerical Simulation ◽  
Comparative Analysis ◽  
Air Temperature ◽  
Thermal Environment ◽  
Simulation Method ◽  
Internal Environment ◽  
Numerical Simulation Method ◽  
Calculation Results ◽  
Noise Barrier ◽  
Air Vent

The thermal environment inside a fully-enclosed subway noise barrier shall be designed according to underground section tunnel standards. This article constructs a model using practical examples, simulates calculations on fully-enclosed noise barrier installations both with and without air vents via a threedimensional numerical simulation method, and then conducts a comparative analysis of the effects noise barrier lengths and air vent widths have on an internal thermal environment. The calculation results show that when the length of the fully-enclosed noise barrier without air vents was 100m, the internal thermal environment exceeded the limit; as the width of the air vents increased, the temperature in the internal environment gradually decreased, but the reduction was less once the air vent width exceeded 2 m; When the top air vent width was 2 m, and the noise barrier length was 100m, the thermal environment was found to meet requirements. As the noise barrier length increased, the internal air temperature exceeded the standards by varying degrees.

scholarly journals A Numerical Study of Underground Cavern Stability by Geostress Characteristics

2016 ◽  
Vol 2016 ◽  
pp. 1-13
Author(s):  
Xiao-Jing Li ◽  
Li-Ge Wang ◽  
Wei-Min Yang
Keyword(s):  
Numerical Study ◽  
Pressure Coefficient ◽  
Side Wall ◽  
Surrounding Rock ◽  
High Mountain ◽  
Burial Depth ◽  
Underground Cavern ◽  
Rock Cavern ◽  
The Stability ◽  
Cavern Stability

The stability of underground cavities is of increasing importance considering the predominant cavity locations built up in high mountain and canyon environments. Such cavity locations are characterized by a high initial in situ stress, which results in brittle fracture and deformation of the surrounding rock during cavity construction. This paper presents a numerical study of underground cavern stability considering four factors, namely, mechanical property of surrounding rock, cavern burial depth, lateral pressure coefficient in horizontal direction, and the angle included between plant longitudinal axis and horizontal principal stress. Analytical methods including the key point displacement in side wall, plastic zone volume, and splitting fracture volume are used to characterize the stability of underground cavern. A modified formula to predict side wall displacement is proposed based on prior work, which is applicable to 3D computation model by taking horizontal geostress in two directions into account. Eventually, the optimal layout of underground cavern is put forward under different conditions of geostress field.

scholarly journals Spatial and Temporal Distribution Law and Influencing Factors of the Mining-Induced Deformation and Failure of Gas Boreholes

2018 ◽  
Vol 2018 ◽  
pp. 1-15
Author(s):  
Fei Xue ◽  
Xiaowei Feng
Keyword(s):  
Numerical Simulation ◽  
Temporal Distribution ◽  
Simulation Method ◽  
Mining Area ◽  
Coal Face ◽  
Distribution Law ◽  
Deformation And Failure ◽  
Shear Stability ◽  
Hole Position ◽  
The Stability

Because gas boreholes are easy to damage by integrated coal mining and gas exploration, based on the practice of relieving pressure in deep thin coal seams in the Huainan mining area, a multidimensional coupling numerical simulation method was used to reveal the space-time evolution characteristics and influence factors of fracture deformation of gob-side gas boreholes. Results indicate that the danger zone for borehole fractures is primarily between 5 and 12 m above the roof of the roadway. The final-hole position has little effect on the stability of boreholes, and migrating the open-hole position to the entity coal side and roadway roof side can improve the stability of the borehole. The initial failure of the borehole occurs at a distance of 10 m behind the coal face. The failure of the borehole is largely stable at a distance of 100 to 120 m behind the coal face. With the increase in mining height, which leads to an increase in the movement of strata and an increase in pressure relief range, the shear stability of the borehole is reduced, and the extrusion stability of the borehole is improved. A hard roof condition promotes borehole shear stability, while a weak roof condition promotes borehole extrusion stability. This change can decrease the maintenance difficulty associated with “minor supports” in boreholes to a certain extent by reinforcing the support strength of “primary supports” in roadway retaining walls. The simulation results are consistent with observed results for the 11 test boreholes, and the accuracy of the numerical simulation is verified.

Analyses of Actual Measurement and Numerical Simulation on Gently Inclined Thin Seam

2011 ◽  
Vol 361-363 ◽  
pp. 130-134
Author(s):  
Jian Xin Tang ◽  
Le Le Sun ◽  
Yue Hua Deng ◽  
Hua Hui Jin
Keyword(s):  
Numerical Simulation ◽  
Dynamic Pressure ◽  
Pressure Coefficient ◽  
River Mouth ◽  
Main Roof ◽  
Simulation Method ◽  
Actual Measurement ◽  
Working Face ◽  
Thin Seam ◽  
Working Resistance

Based on the numerical simulation method and actual measurement analyses, characteristics of working face mineral pressure of the River Mouth Mine has been analyzed and this paper has obtained the following results: First weighting step of the main roof is 23.2 m, the average dynamic pressure coefficient is 1.54~1.74, mine strata behaviors is fiercer; hydraulic prop’s average working resistance is 45.72 KN of each, which indicates hydraulic prop’s working resistance has larger surplus coefficient, some measures should be taken to increase utilization ratio; advanced support length of return airway and mechanical roadway should reach to 30 m, the method and results can be used to improve support pattern of working face and guide safety production.

Numerical Simulation on Similarity of Thermal-Mechanical Effects of Thin-Walled Pressure Vessel Irradiated by Laser

2011 ◽  
Vol 314-316 ◽  
pp. 1965-1969 ◽  
Author(s):  
Yu Heng Wang ◽  
Feng Liu ◽  
Xiang Hua Zhang ◽  
Sheng Ding
Keyword(s):  
Numerical Simulation ◽  
Pressure Vessel ◽  
Continuous Wave ◽  
Simulation Method ◽  
Physical Parameters ◽  
Mechanical Effects ◽  
Calculation Results ◽  
Scale Down ◽  
Thin Walled ◽  
Reduced Scale

In laser process and laser scientific experiments it is an important research method to investigate analogy of physical parameters between the scale down models and the prototype structure by reduced-scale experiments. To the problem of the thermal-mechanical effects of the thin-walled pressure vessel irradiated by continuous wave (CW) laser, a series of approximatively geometrically scaling models with different scale-ratios are established in this paper. Laser flux and ratios of r(radius of laser spot) to R(radius of shells) keep the same for each scaling model. The similarity regularities of thermal-mechanical effects are analyzed and discussed by means of FEM numerical simulation method. The calculation results can give a guide to design for the scale down models and select for laser parameters in reduced-scale experiments.

scholarly journals Numerical Simulation on the Stability of Surrounding Rock of Horizontal Rock Strata in the Tunnel

2018 ◽  
Vol 3 (12) ◽  
pp. 1189 ◽  
Author(s):  
Nian Zhang ◽  
Weihong Wang ◽  
Zhuoqiang Yang ◽  
Jianian Zhang
Keyword(s):  
Numerical Simulation ◽  
Reference Value ◽  
Simulation Method ◽  
Vertical Displacement ◽  
Surrounding Rock ◽  
Tunnel Construction ◽  
Geological Condition ◽  
Deformation And Failure ◽  
The Stability ◽  
Rock Strata

Horizontal rock strata is a geological condition of rock which is often encountered in the tunnel construction, and it has an important influence on the tunnel construction, it is necessary to analyze and study the stability of horizontal rock strata in tunnel construction to ensure the tunnel construction’s safety and efficiency. By taking “Xishan Highway Tunnel” as the research object, and using the numerical simulation method, the numerical model of the tunnel has been established in the Midas/GTS to simulate the tunnel excavation under the horizontal rock strata condition，and the deformation and failure mechanism of surrounding rock and the influence factors of surrounding rock stability after are studied and analyzed. The research focused on the displacement of surrounding rock horizontal and vertical deformation, the results show that the vertical displacement of the surrounding rock is obviously greater than that of other parts during the excavation of the horizontal rock tunnel. According to the calculation results, the optimization measures of horizontal stratum tunnel construction method are put forward, which has important reference value for ensuring the construction safety and construction quality.

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