Research on Rock Burst Loading Test and PFC3D Numerical Simulation

2011 ◽  
Vol 243-249 ◽  
pp. 3012-3020 ◽  
Author(s):  
Yu Zhou ◽  
Shun Chuan Wu ◽  
Qing Liang Wu ◽  
Yu Tao Ma ◽  
Yong Tao Gao
Keyword(s):  
Laboratory Test ◽  
Rock Burst ◽  
Failure Process ◽  
Simulation Method ◽  
Exposed Surface ◽  
Loading Test ◽  
Tunnel Excavation ◽  
Burst Test ◽  
Maximal Load ◽  
Deep Rock

During the tunnel excavation in Zhang-Shi Expressway 2nd-Stage Project, rock burst phenomenon has occurred. Limy dolomite obtained from tunnel rock burst area is used to conduct laboratory loading rock burst test with simulation system of deep rock burst. Simultaneously, based on Particle Flow Theory and PFC3D program, a load-unload code is developed by fish language embedded in PFC3D to carry out simulation of laboratory loading rock burst test. Laboratory test result shows that the rock burst type and intensity of specimen are lagged and severe, respectively; During the test process, a spot of particles eject from the exposed surface; Obvious slabbing phenomenon can be seen on the exposed surface and the separate face of rock slab is parallel to the direction of maximal load σ1 as consistent with the actual phenomenon of engineering rock burst. In the loading rock burst simulation, the load grade, stress-step curve and failure mode of rock burst are almost consistent with the laboratory test. This simulation method describes the failure process actually and subtly, and reveals that the specimen fracture mechanism of loading rock burst is tensile type. Finally, some differences between loading and unloading tests of rock burst are discussed.

scholarly journals Experimental Investigation on the Energy Properties and Failure Process of Thermal Shock Treated Sandstone Subjected to Coupled Dynamic and Static Loads

Minerals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 25
Author(s):  
Xiang Li ◽  
Si Huang ◽  
Tubing Yin ◽  
Xibing Li ◽  
Kang Peng ◽  
...  
Keyword(s):  
Thermal Shock ◽  
Split Hopkinson Pressure Bar ◽  
Failure Process ◽  
Air Cooling ◽  
Hopkinson Pressure Bar ◽  
Loading Test ◽  
Rock Engineering ◽  
Deep Rock ◽  
Pressure Bar ◽  
Cooling Air

Thermal shock (TS) is known as the process where fractures are generated when rocks go through sudden temperature changes. In the field of deep rock engineering, the rock mass can be subjected to the TS process in various circumstances. To study the influence of TS on the mechanical behaviors of rock, sandstone specimens are heated at different high temperatures and three cooling methods (stove cooling, air cooling, and freezer cooling) are adopted to provide different cooling rates. The coupled dynamic and static loading tests are performed on the heated sandstone through a modified split Hopkinson pressure bar (SHPB) system. The influence of heating level and cooling rate on the dynamic compressive strength, energy dissipations, and fracturing characteristics is investigated based on the experimental data. The development of the microcracks of the sandstone specimens after the experiment is analyzed utilizing a scanning electron microscope (SEM). The extent of the development of the microcracks serves to explain the variation pattern of the mechanical responses and energy dissipations of the specimens obtained from the loading test. The findings of this study are valuable for practices in rock engineering involving high temperature and fast cooling.

scholarly journals Triaxial Loading and Unloading Tests on Dry and Saturated Sandstone Specimens

2019 ◽  
Vol 9 (8) ◽  
pp. 1689 ◽  
Author(s):  
Diyuan Li ◽  
Zhi Sun ◽  
Quanqi Zhu ◽  
Kang Peng
Keyword(s):  
Triaxial Compression ◽  
Failure Process ◽  
Failure Behavior ◽  
Compression Tests ◽  
Loading Test ◽  
Rock Engineering ◽  
Sandstone Rock ◽  
Water Conditions ◽  
Deep Rock ◽  
Loading And Unloading

The brittle failure of hard rock due to the excavation unloading in deep rock engineering often causes serious problems in mining and tunneling engineering, and the failure process is always affected by groundwater. In order to investigate the effects of stress paths and water conditions on the mechanical properties and failure behavior of rocks, a series of triaxial compression tests were conducted on dry and saturated sandstones under various loading and unloading paths. It was found that when the sandstone rock samples are saturated by water, the cohesion, the internal friction angle and the Young’s modulus will decrease but the Poisson′s ratio will increase. The fracturing characteristics of the sandstone specimens are related to the initial confining pressure, the stress paths and the water conditions from both macroscopic and microscopic viewpoints. The failure of sandstone in unloading test is more severe than that under loading test, particularly for dry sandstone samples. In unloading test, the energy is mainly consumed for the circumferential deformation and converted into kinetic energy for the rock bursts. The sandstone is more prone to produce internal cracks under the effect of water, and the absorbed energy mainly contributes to the damage of rock. It indicates that the possibility of rockburst in saturated rock is lower than the samples in dry condition. It is important to mention that water injection in rock is an effective way to prevent rockburst in deep rock engineering.

scholarly journals Research on the Source Mechanism and Source Prevention and Control System of Deep Rock Burst

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Shuai Di
Keyword(s):  
Control System ◽  
Rock Mass ◽  
Rock Burst ◽  
Prevention And Control ◽  
Economic Benefits ◽  
Efficient Production ◽  
Targeted Prevention ◽  
Working Face ◽  
Deep Rock ◽  
And Control

Deep rock burst accidents occur frequently and become increasingly serious. Further improving the effectiveness and accuracy of the prevention and control of rock burst, ensuring the safe and efficient production of mines, clarifying the basic causes of disasters, and refining the type of deep rock burst are the most important key links. Aiming at the problems such as unclear incentives and types and the lack of effective and targeted prevention measures of deep rock burst, taking Xin’an Mine as the research background, based on the energy theory, the coal and rock mass multisource energy unified equation was established to analyze coal and rock mass instability mechanism. According to the different degrees of participation of various factors, the types of deep rock burst are determined as three categories and four types, and the corresponding judgment criteria are proposed. The precise prevention and control system for the source of rock burst with Xin’an characteristics is proposed, successfully applied to the 8101 working face, which not only guarantees the safe production of the working face, but also achieves good economic benefits. The research results lay the foundation for improving the accuracy and precision of the prevention and control of deep rock burst and provide theoretical guidance for the safe and efficient mining of the mine.

Analysis on Effect of Tunnel Crossing Underneath Foundation of Tall Buildings on Anti-Seismic Mortar Anchor in Weathered Rock Area

2012 ◽  
Vol 446-449 ◽  
pp. 2581-2589
Author(s):  
Xiao Bei Shi ◽  
Kai Wei ◽  
Bing Long Wang ◽  
Da Wei Huang
Keyword(s):  
High Speed ◽  
Failure Process ◽  
Tall Buildings ◽  
Element Model ◽  
Tunnel Excavation ◽  
High Speed Railway ◽  
Weathered Rock ◽  
Whole Process ◽  
Influence Area ◽  
Before And After

Depending on a project of constructing a tunnel of high-speed railway which crosses underneath the foundation of tall buildings in weathered rock area, the paper analyzes the failure process and its law of anti-seismic mortar anchors under the foundation of tall buildings by simulating the whole process of construction with finite element model. Then the coverage scope, influence rules and extent of tunnel excavation on the anti-pulling effect and stability of mortar anchors are analyzed according to the changes of lateral pressure and axial force of anti-seismic mortar anchors before and after construction. The results show that the influence area can be divided into three parts， of which the main area where the anti-seismic mortar anchors are badly affected is on the top of the tunnel and extends horizontally to a certain range. Finally, the paper gives an applicable method to estimate the area where the anti-seismic mortar anchors should be strengthened by grouting, which also applies to the similar projects in weathered rock area.

Primary cup fixation with different designs of trapeziometacarpal total joint trapezium components: a radiostereometric analysis in a pig bone model

2011 ◽  
Vol 36 (4) ◽  
pp. 285-290 ◽  
Author(s):  
T. B. Hansen ◽  
M. Meier ◽  
M. C. M. Møller ◽  
K. Larsen ◽  
M. Stilling
Keyword(s):  
Fixation Strength ◽  
Radiostereometric Analysis ◽  
Loading Test ◽  
Bone Model ◽  
Press Fit ◽  
Maximal Load ◽  
Significant Difference ◽  
Joint Prostheses ◽  
Cup Design ◽  
Push Out

High loosening rates of the trapezium components of trapeziometacarpal total joint prostheses have been reported. The purpose of this study was to compare the primary press fit fixation of two different, uncemented cup designs (MOTEC and Elektra) with the primary fixation of a cemented polyethylene cup (DLC) in a pig bone model. We did a push out test to measure the maximal load strength of the implants and a low-pressure cyclic loading test combined with radiostereometric analysis to measure the micromotion of the implants. There was no significant difference in fixation strength between the two uncemented screw cup designs or between the two uncemented screw cups and the cemented polyethylene cup. However, we found that threading of the bone before insertion of the Electra screw cup weakens the primary fixation strength of the implant. The results indicate that focus should be on the insertion technique as well as on the cup design of uncemented trapezium cup implants. Further studies of trapezium implant migration in a clinical setting are needed.

Non-Linear Finite Element Analysis on Composite Shear Wall with Opening

2012 ◽  
Vol 446-449 ◽  
pp. 203-207
Author(s):  
Tie Mei Zhu ◽  
Yan Hua Ye ◽  
Wei Wei ◽  
Wei Qing Liu ◽  
Zi Jun Wang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Failure Process ◽  
Shear Wall ◽  
Loading Test ◽  
Element Analysis ◽  
Linear Finite Element ◽  
Composite Shear Wall ◽  
Non Linear ◽  
Composite Shear

A new composite structure system is proposed in this paper to suit the demand of building energy conservation and heat preservation. Based on the low reversed cyclic loading test, the non-linear finite element (FEM) analysis model of composite shear wall is established by ANSYS so as to study crack status, stress variation characteristics and failure process under the action of horizontal loading. The results of ANSYS finite element analysis show good agreement with the test results.

The Influence of Stress Ratio on the Fracture Behavior of Brittle Materials

2007 ◽  
Vol 353-358 ◽  
pp. 937-940
Author(s):  
Wei Hong Li ◽  
Xiong Chen ◽  
De Shen Zhao ◽  
Yi Wang Bao
Keyword(s):  
Stress State ◽  
Fracture Behavior ◽  
Stress Ratio ◽  
Process Analysis ◽  
Failure Process ◽  
Brittle Materials ◽  
Simulation Method ◽  
Critical Stress Intensity Factor ◽  
Complex Stress State ◽  
Biaxial Stress

The fracture behavior of brittle materials under different stress ratio has been investigated by means of numerical simulation method with software RFPA2D (Realistic Failure Process Analysis). The fracture dependence of brittle material on biaxial plane stress state was confirmed. The results show that the critical stress intensity factor under biaxial stress increases with the increase of biaxial stress ratio. The simulation tests reveal that the biaxial stresses have strong influence on the fracture properties of glass. The results confirmed that the strain criterion of fracture is feasible while brittle materials under complex stress state.

Numerical Simulation on Failure Mechanism of Rock Slope Using RFPA

2011 ◽  
Vol 50-51 ◽  
pp. 568-572 ◽  
Author(s):  
Nu Wen Xu ◽  
Chu Nan Tang ◽  
Chun Sha ◽  
Ru Lin Zhang
Keyword(s):  
Rock Slope ◽  
Slip Surface ◽  
Process Analysis ◽  
Failure Process ◽  
Numerical Code ◽  
Natural State ◽  
Left Bank ◽  
Good Tool ◽  
Deep Rock ◽  
The Stability

This research applied a numerical code, RFPA2D (Realistic Failure Process Analysis) to evaluate the stability and investigate the failure mode of the high rock slope during excavations based on Strength Reduction Method (SRM). The corresponding shapes and positions of the potential slip surfaces are rationally simulated in different stages, and the related safety coefficients are obtained, which agrees well with the allowable minimum safety factors of the slope. The numerical results show that the safety coefficient drops from 1.25 at the natural state to 1.09 after excavation, and then increases to 1.35 after slope reinforcement. Moreover, the potential slip surface of the left bank moves into deep rock mass after taking support measures, which demonstrates the reinforcement is reasonable and efficient. The study shows that cracks and faults will cause crucial influences on the slope stability, and RFPA2D is a good tool to directly display the potential slip surface of the slope, which will offer valuable guidance for bolt support.

Optimization Analysis of Different Excavation Offsets in Railway Pilot Tunnel by CRD Method

2014 ◽  
Vol 505-506 ◽  
pp. 134-138
Author(s):  
Chun Kui Li
Keyword(s):  
Production Efficiency ◽  
Ground Surface ◽  
Simulation Method ◽  
Subway Station ◽  
Optimization Analysis ◽  
Tunnel Excavation ◽  
Construction Model ◽  
Surface Settlements ◽  
Stress Variations ◽  
Optimal Construction

This paper focuses on the construction of 10 railway pilot tunnels by CRD method in Jiefang Road subway station in Changchun. To achieve the optimal construction offsets during the pilot tunnel excavation, reduce the impacts of group cavern effect, and maximize the production efficiency, the construction model of railway pilot tunnel in subway station was created by the finite difference software Flac3D. The author used the numerical simulation method to analyze the ground surface settlements and the stress variations with three different construction offsets. Then the optimal construction offset was obtained. It could provide a theoretical guidance to the construction of a similar project.

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