scholarly journals Study on the Seismic Performance of Small-Diameter Bolts Reinforced in Grottoes

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Ningbo Peng ◽  
Bo Sun ◽  
Jizhong Huang ◽  
Yun Dong ◽  
Ye Zhu
Keyword(s):  
Rock Mass ◽  
Seismic Performance ◽  
Axial Force ◽  
Small Diameter ◽  
Vertical Direction ◽  
World Heritage Site ◽  
Dynamic Responses ◽  
Structural Defects ◽  
Seismic Capacity ◽  
Yungang Grottoes

The Yungang Grottoes, a World Heritage Site in Datong, consist of 252 caves that are noted for their collection of 5th- and 6th-century Buddhist grotto sculptures and reliefs. Various diseases have appeared in the grottoes under the general influence of natural and artificial factors. Bolt support is a commonly employed method for grotto reinforcement and has been widely applied in many projects. Small-diameter bolts have also been used in the reinforcement projects at the Yungang Grottoes, but the corresponding effect on the seismic performance of grottoes is still unclear. In this paper, a dynamic analysis via the numerical modelling of an ear grotto of the 19th grotto in Yungang is established, and the rock displacement, acceleration, and bolt axial force responses under a seismic wave are analyzed. The results show that the seismic dynamic responses of grottoes are greatly affected by the cliff structure. The displacement and acceleration responses of the cliff body vary greatly within the abrupt transition of the cliff structure. Based on this variation, the seismic capacity of small-diameter bolts in the vertical direction is greater than that in the horizontal direction. The axial force of a bolt is small at both ends of the bolt, large in the middle of the bolt, small on the top of a cliff, and large at the bottom of the cliff. Although the axial force is small, the upper rock mass of the grotto has a tendency to undergo relative movement compared with the outer rock mass. The results also indicate that based on the structural defects in the vertical direction of the cliff body caused by grotto excavation, the inclined angle of the bolt should be increased as far as possible or vertical support should be adopted to enhance the stability of the rock mass at the top of the grotto.

scholarly journals Study on the Seismic Performance of Small-diameter Bolts Reinforced in Grottoes

2020 ◽  
Author(s):  
Ningbo Peng ◽  
Bo Sun ◽  
Jizhong Huang ◽  
Yun Dong ◽  
Ye Zhu
Keyword(s):  
Rock Mass ◽  
Seismic Performance ◽  
Axial Force ◽  
Small Diameter ◽  
Vertical Direction ◽  
World Heritage Site ◽  
Dynamic Responses ◽  
Structural Defects ◽  
Seismic Capacity ◽  
Yungang Grottoes

Abstract The Yungang Grottoes, a World Heritage Site in Datong, consist of 252 caves that are noted for their collection of 5th and 6th century Buddhist grotto sculptures and reliefs. Various diseases have appeared in the grottoes under the general influence of natural and artificial factors. Bolt support is a commonly employed method for grotto reinforcement and has been widely applied in many projects. Small-diameter bolts have also been used in the reinforcement projects at the Yungang Grottoes, but the corresponding effect on the seismic performance of grottoes is still unclear. In this paper, a dynamic analysis via the numerical modelling of an ear grotto of the 19th grotto in Yungang was established, and the rock displacement, acceleration and bolt axial force responses under a seismic wave are analyzed. The results show that the seismic dynamic responses of grottoes are greatly affected by the cliff structure. The displacement and acceleration responses of the cliff body vary greatly within the abrupt transition of the cliff structure. Based on this variation, the seismic capacity of small-diameter bolts in the vertical direction is greater than that in the horizontal direction. The axial force of a bolt is small at both ends of the bolt, large in the middle of the bolt, small on the top of a cliff and large at the bottom of the cliff. Although the axial force is small, the upper rock mass of the grotto has a tendency to undergo relative movement compared with the outer rock mass. The results also indicate that based on the structural defects in the vertical direction of the cliff body caused by grotto excavation, the inclined angle of the bolt should be increased as far as possible or vertical support should be adopted to enhance the stability of the rock mass at the top of the grotto.

SEISMIC CAPACITY OF MEDIUM SIZE CONTINUOUS BRIDGES WITH LEAD-RUBBER BEARINGS

2019 ◽  
Vol 3 (Special Issue on First SACEE'19) ◽  
pp. 199-206
Author(s):  
Bertha Olmos ◽  
José Jara ◽  
José Luis Fabián
Keyword(s):  
Seismic Performance ◽  
Seismic Vulnerability ◽  
Base Isolation ◽  
Elastic Behaviour ◽  
Medium Size ◽  
Nonlinear Behaviour ◽  
Seismic Capacity ◽  
Damage Scenarios ◽  
Isolation Systems ◽  
Rubber Bearings

This paper investigates the effects of the nonlinear behaviour of isolation pads on the seismic capacity of bridges to identify the parameters of base isolation systems that can be used to improve seismic performance of bridges. A parametric study was conducted by designing a set of bridges for three different soil types and varying the number of spans, span lengths, and pier heights. The seismic responses (acceleration, displacement and pier seismic forces) were evaluated for two structural models. The first model corresponded to the bridges supported on elastomeric bearings with linear elastic behaviour and the second model simulated a base isolated bridge that accounts for the nonlinear behaviour of the system. The seismic demand was represented with a group of twelve real accelerograms recorded on the subduction zone on the Pacific Coast of Mexico. The nonlinear responses under different damage scenarios for the bridges included in the presented study were estimated. These results allow determining the seismic capacity of the bridges with and without base isolation. Results show clearly the importance of considering the nonlinear behaviour on the seismic performance of bridges and the influence of base isolation on the seismic vulnerability of medium size bridges.

A Modular Mechanism for Downhole Weight-on-Bit and Torque Reaction in Small Diameter Boreholes

2021 ◽  
pp. 1-15
Author(s):  
Anirban Mazumdar ◽  
Stephen Buerger ◽  
Adam Foris ◽  
Jiann-cherng Su
Keyword(s):  
Axial Force ◽  
Small Diameter ◽  
Field Testing ◽  
Drill String ◽  
Force Transmission ◽  
Drilling Performance ◽  
Weight On Bit ◽  
In Series ◽  
Mechanical Devices ◽  
Scalable Design

Abstract Drilling systems that use downhole rotation must react torque either through the drill-string or near the motor to achieve effective drilling performance. Problems with drill-string loading such as buckling, friction, and twist become more severe as hole diameter decreases. Therefore, for small holes, reacting torque downhole without interfering with the application of weight-on-bit, is preferred. In this paper we present a novel mechanism that enables effective and controllable downhole weight on bit transmission and torque reaction. This scalable design achieves its unique performance through four key features: 1) mechanical advantage based on geometry, 2) direction dependent behavior using rolling and sliding contact, 3) modular scalability by combining modules in series, and 4) torque reaction and weight on bit that are proportional to applied axial force. As a result, simple mechanical devices can be used to react large torques while allowing controlled force to be transmitted to the drill bit. We outline our design, provide theoretical predictions of performance, and validate the results using full-scale testing. The experimental results include laboratory studies as well as limited field testing using a percussive hammer. These results demonstrate effective torque reaction, axial force transmission, favorable scaling with multiple modules, and predictable performance that is proportional to applied force.

Partial Admission, Axial Impulse Type Turbine Design and Partial Admission Radial Turbine Test for SCO2 Cycle

2017 ◽  
Author(s):  
Hyungki Shin ◽  
Junhyun Cho ◽  
Young-Jin Baik ◽  
Jongjae Cho ◽  
Chulwoo Roh ◽  
...  
Keyword(s):  
Axial Force ◽  
Flow Rate ◽  
Volume Flow Rate ◽  
Small Diameter ◽  
Volume Flow ◽  
Working Fluid ◽  
Rotating Speed ◽  
Turbo Generator ◽  
Partial Admission ◽  
Reduce Development Time

Power generation cycle — typically Brayton cycle — to use CO2 at supercritical state as working fluid have been researched many years because this cycle increase thermal efficiency of cycle and decrease turbomachinery size. But small turbomachinery make it difficult to develop proto type Supercritical Carbon dioxide (S-CO2) cycle equipment of lab scale size. KIER (Korea Institute of Energy Research) have been researched S-CO2 cycle since 2013. This paper is about 60kWe scale and sub-kWe class turbo generator development for applying to this S-CO2 cycle at the lab scale. A design concept of this turbo-generator is to use commercially available components so as to reduce development time and increase reliability. Major problem of SCO2 turbine is small volume flow rate and huge axial force. High density S-CO2 was referred as advantage of S-CO2 cycle because it make small turbomachinery possible. But this advantage was not valid in lab-scale cycles under 100kW because small amount volume flow rate means high rotating speed and too small diameter of turbine to manufacture it. Also, high inlet and outlet pressure make huge axial force. To solve these problem, KIER have attempt various turbines. In this paper, these attempts and results are presented and discussed.

scholarly journals Road Vehicle-Bridge Interaction considering Varied Vehicle Speed Based on Convenient Combination of Simulink and ANSYS

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Helu Yu ◽  
Bin Wang ◽  
Yongle Li ◽  
Yankun Zhang ◽  
Wei Zhang
Keyword(s):  
Reaction Force ◽  
Sudden Change ◽  
Vertical Direction ◽  
Dynamic Responses ◽  
Force Model ◽  
Vertical Acceleration ◽  
Vehicle Speed ◽  
Road Vehicle ◽  
The Road ◽  
Bridge Model

In order to cover the complexity of coding and extend the generality on the road vehicle-bridge iteration, a process to solve vehicle-bridge interaction considering varied vehicle speed based on a convenient combination of Matlab Simulink and ANSYS is presented. In this way, the road vehicle is modeled in state space and the corresponding motion equations are solved using Simulink. The finite element model for the bridge is established and solved using ANSYS. The so-called inter-history iteration method is adopted to realize the interaction between the vehicle model and the bridge model. Different from typical method of road vehicle-bridge interaction in the vertical direction, a detailed longitudinal force model is set up to take into account the effects of varied vehicle speed. In the force model, acceleration and braking of the road vehicle are treated differently according to their mechanical nature. In the case studies based on a simply supported beam, the dynamic performance of the road vehicle and the bridge under varied vehicle speeds is calculated and discussed. The vertical acceleration characteristics of the midpoint of beam under varied vehicle speed can be grouped into two periods. The first one is affected by the load transform between the wheels, and the other one depends on the speed amplitude. Sudden change of the vertical acceleration of the beam and the longitudinal reaction force are observed as the wheels move on or off the bridge, and the bridge performs different dynamic responses during acceleration and braking.

Modeling transient excavation-induced dynamic responses in rock mass using an elasto-plastic cellular automaton

2020 ◽  
Vol 96 ◽  
pp. 103183
Author(s):  
Mei Li ◽  
Wanquan Mei ◽  
Peng-Zhi Pan ◽  
Fei Yan ◽  
Zhenhua Wu ◽  
...  
Keyword(s):  
Rock Mass ◽  
Cellular Automaton ◽  
Dynamic Responses

The Seismic Dynamic Response on the Steel Spatial Arch Truss with 60 m Span and 0.4 Rise-Span Ratio

2011 ◽  
Vol 368-373 ◽  
pp. 850-853
Author(s):  
Hai Wang Li ◽  
Jing Jing Guo ◽  
Jing Liu
Keyword(s):  
Plastic Hinge ◽  
Vertical Direction ◽  
Nonlinear Effects ◽  
Horizontal Displacement ◽  
Vertical Displacement ◽  
Dynamic Responses ◽  
Peak Acceleration ◽  
Displacement Ductility ◽  
Earthquake Action ◽  
Material Nonlinear

In this paper, the elasto-plastic dynamic analysis on the steel spatial arch truss with 60 m span and 0.4 rise-span ratio is carried out under earthquake wave with SAP2000. In the analyses, the geometric and material nonlinear effects are considered at the same time based on the plastic-hinge theory. Under the action of EL wave with the peak increasing gradually, its elasto-plastic dynamic responses have been obtained. The results show that its failure mode under the earthquake action is elasto-plastic dynamic buckling; that its critical peak acceleration of EL earthquake wave when applied in horizontal direction is 808.5 gal, and is 789.0 gal when applied in vertical direction; The ratio of its maximal node horizontal displacement and its structural height is 1/259, and its displacement ductility coefficient is 1.071; The ratio of its maximal node vertical displacement and its structural span is 1/736, and its displacement ductility coefficient is 1.105.

Strengthening Research in the Longitudinal Frames of Prefabricated Structures with Viscous Dampers

2013 ◽  
Vol 671-674 ◽  
pp. 782-785
Author(s):  
Bin He ◽  
Jin Lai Pang ◽  
Cheng Qing Liu
Keyword(s):  
Seismic Performance ◽  
Pushover Analysis ◽  
Vertical Direction ◽  
Time History ◽  
Nonlinear Time History Analysis ◽  
Viscous Dampers ◽  
Existing Building ◽  
Concrete Frame ◽  
Uniform Drift ◽  
Nonlinear Time History

For the lack of research in the longitudinal frame of prefabricated structure for its weak lateral stiffness, pushover analysis is conducted to evaluate the seismic performance of a fabricated concrete frame. Based on case study, the strengthening strategies with viscous dampers are analyzed. In view of the undesirable drift distribution and failure mode in the existing building, it is believed that arrangement of dampers should be designed to attain a uniform drift distribution. Based on the nonlinear time history analysis method, the strategy of damper allocation in vertical direction of the structure is investigated .Results indicate that a proper design might be attained based on the property of existing system, leading to a uniform drift distribution and better seismic performance.

scholarly journals A Vibration-Isolating Blast Technique with Shock-Reflection Device for Dam Foundation Excavation in Complicated Geological Conditions

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Haoran Hu ◽  
Wenbo Lu ◽  
Peng Yan ◽  
Ming Chen ◽  
Qidong Gao
Keyword(s):  
Rock Mass ◽  
Field Experiments ◽  
Vertical Direction ◽  
Wave Impedance ◽  
Shock Reflection ◽  
Dam Foundation ◽  
Geological Conditions ◽  
Production Experiment ◽  
Bench Blasting ◽  
Foundation Rock

Under complicated geological conditions, the vibration in the dam foundation caused by blasting can lead to further deterioration of the foundation rock mass and adversely affect the safety of foundation. In order to effectively control the vibration in dam foundation rock mass, a new bench blasting technique with shock-reflection device is proposed. It introduces a shock-reflection device consisting of high wave impedance block and cushion material, which is placed at the bottom of vertical borehole. This shock-reflection device can effectively reflect the explosion shock wave from vertical direction to horizontal direction after detonation, which can make blasting energy concentrated on the rock mass above dam foundation, so the vibration in the foundation can be controlled. Field blasting experiment was carried out to contrast the blasting induced vibration in foundation rock by bench blasting with shock-reflection device and conventional bench blasting. The results indicate that the vibration in the foundation rock can be reduced by 30%~57%. In addition, the vibration at the bottom of the borehole is also demonstrated by numerical simulation, with results similar to the field experiments. The production experiment results show that the new blasting technique can replace the conventional excavation method of dam foundation in complicated geological conditions, and the new blasting technique has been successfully applied to the Baihetan dam foundation excavation.

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