scholarly journals Research on the Method and Model for Calculating Impact Load in the Rockburst Tunnel

Minerals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 13
Author(s):  
Zhiwei Yan ◽  
Dagang Liu ◽  
Zhilong Wang ◽  
Daming Zhao ◽  
Hongtao Tian
Keyword(s):  
Impact Load ◽  
Design Method ◽  
Pressure Coefficient ◽  
Side Wall ◽  
Calculation Model ◽  
Load Factor ◽  
Circular Tunnel ◽  
Supporting Structure ◽  
The Difference ◽  
The Impact

Among several design methods of tunnel supporting structure, the load-structure method is widely used in different countries, but the determination of load is essential in this design method. The problem of rockburst is becoming more prominent as tunnel engineering enters the deep underground space. However, the research on the impact load on the supporting structure is insufficient in relevant fields. Therefore, from the perspective of energy, this paper deduces the method and model for calculating the impact load of the rockburst tunnel acting on the supporting structure by using the method of structural mechanics first, after the location effect of impact load is determined under different section types and different section sizes. The results indicated that: dynamic load factor K is related to the stiffness EI and supporting size coefficient K0 of the supporting structure, also the difference of impact load in different sections is proved. Tunnel rockburst-prone location is related to lateral pressure coefficient, thus when λ = 1, the probability of rockburst in the whole circular tunnel is the same, while side wall and vault are prone to rockburst in single-track horseshoe tunnel, and the side wall is prone to rockburst in double-track horseshoe tunnel; furthermore when λ > 1, the vault and the inverted arch are prone to rockburst; additionally, when λ < 1, the rockburst is most likely to occur in the arch waist of the circular tunnel and the side walls and the arch waist of the horseshoe tunnel. Finally, the rockburst tunnel’s local load-structure calculation model and the calculation process based on the model are provided.

Grinding Force Model for Low-Speed Grinding Based on Impact Principle

2013 ◽  
Vol 797 ◽  
pp. 123-128
Author(s):  
Ming He Liu ◽  
Xiu Ming Zhang ◽  
Shi Chao Xiu
Keyword(s):  
Sliding Friction ◽  
Impact Load ◽  
Grinding Force ◽  
Calculation Model ◽  
Force Model ◽  
Grinding Process ◽  
Low Speed ◽  
Impact Area ◽  
Force Mechanism ◽  
The Impact

In the low-speed grinding process, the force generated when the wheel grinding the workpiece is the result of sliding friction, plough and cutting. While in the actual study, the cutting process has attracted extensive attention. Impact effect to the entire grinding process on the contact is ignored so that the error exists between the calculation grinding force and the measured grinding force. Basing on the shock effect to the grinding process, the paper divides the contact area into impact area and cutting area. And the model of impact load generated from single grit is built. Moreover, the grinding force theoretical calculation model and total grinding force mathematical model is also constructed by analyzing the impact load affecting on the grinding force mechanism. Finally experimental study verifies the correctness of theoretical analysis.

scholarly journals Failure Characteristics of Joint Bolts in Shield Tunnels Subjected to Impact Loads from a Derailed Train

2017 ◽  
Vol 2017 ◽  
pp. 1-17 ◽  
Author(s):  
Qixiang Yan ◽  
Zhixin Deng ◽  
Yanyang Zhang ◽  
Wenbo Yang
Keyword(s):  
Impact Load ◽  
Numerical Study ◽  
Design Method ◽  
Shield Tunnel ◽  
Failure Behavior ◽  
Impact Loads ◽  
Fe Model ◽  
Fe Modelling ◽  
Bolt Failure ◽  
The Impact

Impact loads generated by derailed trains can be extremely high, especially in the case of heavy trains running at high speeds, which usually cause significant safety issues to the rail infrastructures. In shield tunnels, such impact loads may not only cause the damage and deformation of concrete segments, but also lead to the failure of segmental joint bolts. This paper presents a numerical study on the failure behavior of segmental joint bolts in the shield tunnel under impact loading resulting from train derailments. A three-dimensional (3D) numerical model of a shield tunnel based on the finite element (FE) modelling strategy was established, in which the structural behavior of the segmental joint surfaces and the mechanical behavior of the segmental joint bolts were determined. The numerical results show that the occurrence of bolt failure starts at the joints near the impacted segment and develops along the travel direction of train. An extensive parametric study was subsequently performed and the influences of the bolt failure on the dynamic response of the segment were investigated. In particular, the proposed FE model and the analytical results will be used for optimizing the design method of the shield tunnel in preventing the failure of the joint bolts due to the impact load from a derailed HST.

Rigid-plastic analysis of floating ice sheets under impact loads

1981 ◽  
Vol 8 (4) ◽  
pp. 409-415
Author(s):  
John B. Kennedy ◽  
K. J. Iyengar
Keyword(s):  
Impact Load ◽  
Design Method ◽  
Yield Criterion ◽  
Ice Sheets ◽  
Contact Radius ◽  
Impact Loads ◽  
Rigid Plastic ◽  
Deformation Response ◽  
Safe Thickness ◽  
The Impact

The deformation response of floating ice sheets under high intensity, short duration loads is examined. Using a rigid-plastic theory, together with a Tresca yield criterion, expressions are derived for the total time of response and the final deformed configuration of floating ice sheets. The influence of the magnitude of the impact load and the load-contact radius on the various design quantities such as deflection profile and stress distribution is discussed. Based on the results derived, a design method is presented to find the safe thickness of a floating ice sheet to sustain a given impact load. The method is illustrated with a numerical example.

Hoisting Dynamics Analysis of Suspended Access Equipment

2010 ◽  
Vol 163-167 ◽  
pp. 708-712
Author(s):  
Xi Jian Zheng ◽  
Zhen Lu ◽  
Zheng Yi Xie ◽  
Yan Hong
Keyword(s):  
Impact Load ◽  
Load Factor ◽  
Acceleration Response ◽  
Response Curves ◽  
Load Effect ◽  
Structure Dynamics ◽  
Mechanics Model ◽  
Dynamics Response ◽  
The Impact ◽  
Dynamic Load Factor

Suspended access equipment (SAE) is widely used and the impact load effect on the structure of SAE while hoisting from the ground is to be researched. In the paper, three methods were taken to analyze hoisting dynamics response of SAE, including energy equation method, mechanics model calculation and finite element method (FEM), and it turns out that FEM is the perfect one. By using FEM, structure dynamics response curve and dynamic load factor were obtained. The effect factors of structure dynamics response were also analyzed. Measures were given finally to improve the effect of hoisting impact load by analyzing displacement and acceleration response curves of SAE.

Simplified Spur Gear Design

2016 ◽  
Author(s):  
Edward E. Osakue
Keyword(s):  
Contact Stress ◽  
Design Method ◽  
Spur Gear ◽  
Load Factor ◽  
Spur Gears ◽  
Bending Stress ◽  
Hertz Contact ◽  
Gear Design ◽  
Simplified Method ◽  
The Difference

A simplified design method (SDM) for spur gears is presented. The Hertz contact stress and Lewis root bending stress capacity models for spur gears have been reformulated and formatted into simplified forms. A scheme is suggested for estimating the AGMA J-factor in Lewis root bending stress for spur gears from a single curve for both pinion and gear instead of the conventional two curves. A service load factor is introduced in gear design that accounts for different conventional rated load modifier factors. It represents a magnification factor for the rated load in a gear design problem. Two design examples are considered for applications of the stress capacity models. In Example 1, the Hertz contact stress of the SDM deviates from AGMA value by 1.95%. The variance in Example 2 between the contact stress of the SDM and FEM is 1.184% while that between SDM and AGMA is 0.09%. The root bending stress of AGMA and SDM for the pinion in Example 1 differs by 1.44% and that for the gear by 6.59%. The difference between the root bending stress of AGMA and SDM for pinion and gear in Example 2 is 0.18%. These examples suggest that the new simplified method gives results that compare very favorably with both AGMA and FEM solutions. The simplified method developed is recommended mainly for preliminary design when quick but reliable solutions are sought.

Numerical Solution of Elas-Plastic Impact Load of Tube Column

2008 ◽  
Vol 33-37 ◽  
pp. 363-368
Author(s):  
Chun Yang Liu ◽  
Bing Xin Li ◽  
Jin San Ju ◽  
Xiu Gen Jiang ◽  
Xiao Chuan You
Keyword(s):  
Rigid Body ◽  
Contact Time ◽  
Impact Load ◽  
Local Buckling ◽  
Tube Model ◽  
Mass Ratio ◽  
The Difference ◽  
Reduction Effect ◽  
The Impact ◽  
Peak Value

The explicit numerical method is used to trace the impact procedure of the tube columns impacted by a rigid body. The bar and rectangle tube models are both used to simulate the tube column. The elastic and elas-plastic impact load with different mass ratio and impact speed are obtained. The calculation results show that: for elastic models, the bigger the mass ratio and the higher the rigid body speed, the bigger the peak value of elastic impact load; at the same time, the more obvious the reduction effect of local buckling of rectangle tube on the peak value of impact load and the longer the contact time of tube model; so the peak value of impact load of the rectangle tube is not proportional to the rigid body speed. The stress wave in the tube causes a little difference between the load curves of tube model and bar model. For elas-plastic models, the higher the rigid body speed and the smaller the mass ratio, the bigger the peak value of impact load and the longer the contact time. The higher the rigid body speed, the bigger the difference between elastic and elas-plastic impact load peak value due to the expanding of plasticity. Because of the effect of local buckling, the peak value of elas-plastic impact load of rectangle tube is always lower than that of bar.

Study of Seismic Design Method for Frame Supporting Structure with Prestressed Anchors

2011 ◽  
Vol 261-263 ◽  
pp. 1139-1144
Author(s):  
Jian Hua Dong ◽  
Wei Ma ◽  
Yan Peng Zhu
Keyword(s):  
Seismic Design ◽  
Design Method ◽  
Earth Pressure ◽  
Calculation Model ◽  
Dynamical Analysis ◽  
Dynamic Calculation ◽  
Engineering Project ◽  
Systematic Calculation ◽  
Supporting Structure ◽  
Seismic Design Method

Frame supporting structure with prestressed anchors is a new anchoring technology applied in slope reinforcement in recent years. Its dynamical analysis and seismic design is a big challenge, a set of systematic calculation methods can not be found for the time being. This paper shall first evaluate the calculation formula of anchoring slope earthquake earth pressure, then establish dynamic calculation model of frame supporting structure with prestressed anchors, solve using FORCE METHOD, finally apply the proposed method in engineering project. The result shows that this method is applicable to loess areas with uniform soil texture, providing the theoretical basis for seismic design of frame supporting with prestressed anchors.

scholarly journals Numerical Simulation of Impact Tension for Mooring Cable of Underwater Monitoring Platform

2012 ◽  
Vol 229-231 ◽  
pp. 2060-2064
Author(s):  
Kong De He ◽  
Zi Fan Fang ◽  
Yi Zhang ◽  
Wei Hua Yang
Keyword(s):  
Impact Load ◽  
Tangential Direction ◽  
Force Characteristic ◽  
Dynamical Response ◽  
Impact Action ◽  
Mooring Cable ◽  
The Difference ◽  
The Impact ◽  
Monitoring Platform ◽  
Action Force

The dynamical model of underwater monitoring platform is formulated aimed at the dynamical response by the action of flow force, based on Hopkinson impact load theory, taken into account the catenoid effect of mooring cable and revised the difference of tension and tangential direction action force by equivalent modulus of elasticity. And solved the equation by hydraulics theory and structural mechanics theory of oceaneering, studied the action force characteristic of mooring cable and motion characteristic of buoy. Through the result the conclusion can be got the buoy will engender biggish heave and swaying displacement, but the swaying displacement got stable quickly and the heaven displacement got vibration for the vortex-induced action by the flow; because the vortex-induced action and the impact action between buoy and the mooring cable, the tension made great changes when the mooring cable was Relaxation-tension.

Investigating the influence of Taekwondo body protectors size on shock absorption

2020 ◽  
pp. 1-9
Author(s):  
Hee Seong Jeong ◽  
Sae Yong Lee ◽  
Hyung Jun Noh ◽  
David Michael O’Sullivan ◽  
Young Rim Lee
Keyword(s):  
Impact Strength ◽  
Impact Force ◽  
Impact Load ◽  
The Body ◽  
Shock Absorption ◽  
Significance Level ◽  
The Difference ◽  
Maximum Impact Force ◽  
Impact Energies ◽  
The Impact

OBJECTIVE: This study aims to compare and analyze the difference of impact force attenuation according to size and impact location on a Taekwondo body protector. METHODS: Body protectors sized 1 to 5, were impact tested by equipment based on the specifications in the European standard manual (EN 13277-1, 3). The impactor release heights were set to match impact energies of 3 and 15 J. The impactor was made from a 2.5 kg cylindrically cut piece of aluminum. Each body protector was impacted 10 times at the two impact energies and two locations. The differences in performance for each body protector size were compared using a two-way analysis of variance with a significance level of p< 005. The effect sizes were investigated using a partial eta squared value (η2). RESULTS: The significant mean differences between the body protector size and impact area (p< 005) and the average impact time of impact strengths 3 and 15 J were 0.0017 and 0.0012 s, respectively In addition, when an impact strength of 15 J was applied, the maximum resulting impact force exceeded 2000 N for both locations on all sizes. Furthermore, at an impact strength of 3 J size 3 significantly reduced the impact force more than the other sizes; however, size 1 showed the greatest shock absorption at an impact of 15 J. CONCLUSION: The results of this study show that the shock absorption of body protectors does not increase according to size; i.e., a larger body protector does not reduce the impact load more effectively. To improve safety performance, we recommend a maximum impact force of 2000 N or less for all body protectors.

Application of Horizontal Bamboo Bars in Highway Bridge Embankment Backfill

2014 ◽  
Vol 501-504 ◽  
pp. 1424-1428
Author(s):  
Qiang Chen ◽  
Yao Dong Kuang ◽  
Ben Jiao Zhang ◽  
Bin Huang
Keyword(s):  
Effective Treatment ◽  
High Speed ◽  
Impact Load ◽  
Highway Bridge ◽  
Transition Area ◽  
Bridge Abutment ◽  
The Difference ◽  
The Impact ◽  
Highway Embankment

Because the backfill of highway bridge embankment is not dense enough and the located in the hard and soft transition area, the big settlement that threats the safety of driving usually occurs when influenced by the impact load of high-speed vehicles. According to statistic of investigation of the accidents on certain highway, the difference between settlements in bridge abutment and bridge back is around 32mm to 100mm. This kind of big settlement difference is the main reason for bumping and other problems harming the operation of highway. In this paper we experimentally use horizontal bamboo bars used in the construction of side bridge embankment to deal with the continuous backfill settlement, which is effective. Bar pile to treat the settlement of highway embankment backfill is one of the economical, reliable and effective treatment without constructional occupation of driving lanes.

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