Displacement response of buildings under debris flow impact load

With the increasing popularity of high-speed railway, more and more bridges are being constructed in Western China where debris flows are very common. A debris flow with moderate intensity may endanger a high-speed train traveling on a bridge, since its direct impact leads to adverse dynamic responses of the bridge and the track structure. In order to address this issue, a dynamic analysis model is established for studying vibrations of coupled train–track–bridge system subjected to debris flow impact, in which a model of debris flow impact load in time domain is proposed and applied on bridge piers as external excitation. In addition, a six-span simply supported box girder bridge is considered as a case study. The dynamic responses of the bridge and the running safety indices such as derailment factor, offload factor, and lateral wheel–rail force of the train are investigated. Some influencing factors are then discussed based on parametric studies. The results show that both bridge responses and running safety indices are greatly amplified due to debris flow impact loads as compared with that without debris flow impact. With respect to the debris flow impact load, the boulder collision has a more negative impact on the dynamic responses of the bridge and train than the dynamic slurry pressure. Both the debris flow impact intensity and train speed determine the running safety indices, and the debris flow occurrence time should be also carefully considered to investigate the worst scenario.

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Transient simulation on dynamic response of liquid annular seals

Journal of Management Science & Engineering research ◽

10.30564/jmser.v3i1.2597 ◽

2020 ◽

Vol 3 (1) ◽

Author(s):

Li Song ◽

Pingwei Chen ◽

Tong Wang ◽

Wensheng Ma

Keyword(s):

Dynamic Response ◽

Impact Load ◽

Time History ◽

Liquid Viscosity ◽

Rotor Speed ◽

Object A ◽

Displacement Response ◽

Sealing Pressure ◽

Gravity Direction ◽

Annular Seals

Transient change of the operating parameters has a serious influence on the stability of liquid annular seals. Take the liquid annular seals as a research object, a numerical method based on six-degree-of-freedom (6DOF) to analyze the dynamic response of liquid annular seals under gravity impact load. The variations of the force of liquid seal and pressure as well as the axis trajectory in time history are investigated. The influence of different sealing clearance、different liquid viscosity and different rotor speed is also studied. The results show that the maximum sealing pressure and sealing force of gravity direction will increase greatly in a very short time and then reduce rapidly. When sealing clearance increases, the displacement response amplitudes of axis trajectory, the maximum sealing force of gravity direction and maximum sealing pressure also increase. When liquid viscosity increases, the displacement response amplitudes of axis trajectory, the maximum sealing force of gravity direction and maximum sealing pressure decrease. We also found that different rotor speed has almost no influence on the maximum sealing force of gravity direction and maximum sealing pressure.

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Experimental Study on Dynamic Responses of a New Type of Debris Flow Dam under Solid Impact Load

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.723.299 ◽

2015 ◽

Vol 723 ◽

pp. 299-308

Author(s):

Jun Jie Li ◽

Xiu Li Wang ◽

Yan Peng Zhu

Keyword(s):

Debris Flow ◽

Impact Load ◽

Impact Resistance ◽

Dynamic Responses ◽

Gravity Dams ◽

Control Engineering ◽

Combined Structure ◽

New Type ◽

Extent Of Damage ◽

And Control

Dams can effectively alleviate great debris flow hazards to downstream regions, so they has been widely applied to prevention and control engineering of debris flow disaster now. A kind of steel-concrete combined structure with steel braces was presented based on conventional gravity dams, and the superiority of the new structure in terms of impact resistance was verified contrastively by means of model experiments under solid impact. The results show that braces can restrain cracks and reduce their width, thus the extent of damage in impact areas is alleviated effectively. Compared with the conventional dam, the dynamic strains and acceleration peak values of the dam with braces both observably reduce, and the highest reduction ranges of them may be up to 69.2% and 47.8% respectively, so the deformation and vibration are limited by the braces. The dynamic displacement peak values of the new-type dam are significantly less than the conventional dam, and the average reduction range of this index can reach to about 46%, so the structural stiffness has been enhanced by a large margin.

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Study on the Impact Properties of a New Debris Flow Dam Based on Steel-Concrete Composite Structure

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.638-640.2056 ◽

2014 ◽

Vol 638-640 ◽

pp. 2056-2059 ◽

Cited By ~ 1

Author(s):

Ya Xiong Liang ◽

Xiu Li Wang ◽

Chang Wu ◽

Zhi Gang Lv

Keyword(s):

Finite Element ◽

Debris Flow ◽

Impact Force ◽

Impact Load ◽

Weak Link ◽

Time History ◽

Type Model ◽

Finite Element Software ◽

New Type ◽

The Impact

The impact force is one of the most weak link of the dynamics studies of debris flow for many years. To make the structure or components are better able to suffer the impact load such as debris flow, explosions, a new debris flow dam is designed by introducing this new type model with spring. It is simulated under boulder impact by using finite element software LS-DYNA.The stress distribution, impact and displacement time history curve under typical conditions are obtained. The results show that the resist impact effect of new debris flow dam is very obvious.

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Effect of slit size on the impact load against debris-flow mitigation dams

Engineering Geology ◽

10.1016/j.enggeo.2020.105764 ◽

2020 ◽

Vol 274 ◽

pp. 105764 ◽

Cited By ~ 1

Author(s):

Hongsen Hu ◽

Gordon G.D. Zhou ◽

Dongri Song ◽

Kahlil Fredrick E. Cui ◽

Yu Huang ◽

...

Keyword(s):

Debris Flow ◽

Impact Load ◽

Slit Size ◽

The Impact

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Study on Wavelet Denoising of Pulse Impact Force of Non-Viscosity Debris Flow

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.249-250.1040 ◽

2012 ◽

Vol 249-250 ◽

pp. 1040-1046

Author(s):

Hong Kai Chen ◽

Xiao Ying He ◽

Hong Mei Tang ◽

Lan Tang

Keyword(s):

Grain Size ◽

Debris Flow ◽

Impact Force ◽

Solid Phase ◽

Impact Load ◽

Wavelet Denoising ◽

Wavelet Function ◽

Phase Ratio ◽

Threshold Method ◽

Soft Threshold

Noise filtering of impact load spectrum is the key to ensure the impact load of debris flow during the control engineering design of debris flow. As the laboratory impacting test indicates, noise effect in pulse impact force spectrum can be denoised using Daubechie(dbN)and Symlet(symN)wavelet methods, both of which contain hard threshold method and soft threshold method. Analyzed the pulse impact force of non-viscosity debris flow testing results by wavelet denoising method, the testing conditions are A-3(whose grain size is range from 0.3cm to 0.8cm), B-3(whose grain size is range from 0.8cm to 1.5cm) and C-3(whose grain size is range from 1.5cm to 3.0cm),all of whose solid phase ratio are 0.16.The analyzing results show that the denosing effect adopting Db5 wavelet function is superior to ones adopting Sym2 wavelet function, meanwhile, the denosing effect adopting hard threshold method is superior to ones adopting soft threshold method. The results also indicate that the bigger the solid phase ratio is, the bigger the Signal Noise Ratio is, the better the wavelet denosing effect is. These results could provide scientific basis for further accurate experimental study to ensure impact load of non-viscosity debris flow.

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Method to evaluate the effect of inclination angle of steel open-type check dam on debris flow impact load

International Journal of Protective Structures ◽

10.1177/2041419618789702 ◽

2018 ◽

Vol 10 (1) ◽

pp. 95-115 ◽

Cited By ~ 2

Author(s):

Toshiyuki Horiguchi ◽

Yoshiharu Komatsu

Keyword(s):

Debris Flow ◽

Natural Disasters ◽

Inclination Angle ◽

Impact Load ◽

Time History ◽

Check Dam ◽

Open Type ◽

Inclination Angles ◽

The Impact ◽

Type Check

Although the latest statistics indicate a decrease in the number of victims of natural disasters in Japan, the number of sediment disasters has increased. A countermeasure against natural disasters is provided by the installation of a steel open-type check dam (hereafter, open Sabo dam). The open Sabo dam is expected to capture boulders (more than 1.0 m in diameter) contained in debris flow of which boulders concentrate in front part. When a debris flow impacts an open Sabo dam, the large impact load on the steel pipes are caused by the impact of boulders under debris flow. Therefore, it is important to evaluate the impact of both boulders and the following soil and small gravels including fluid force of the open Sabo dam from the design point of view. Although an open Sabo dam has various shapes especially, the every open Sabo dams is evaluated by the same design method in Japan. It is necessary to propose the load evaluation method in the experiment scale in contrast with different shape of open Sabo dam. This article presents an experimental approach to determine the effect of the front inclination angle of steel open Sabo dams on the impact load. The debris flow impacts 1/40 scale models of steel open Sabo dams which are set in a flow channel flume, and the debris flow load is measured by using three load cells placed horizontally at the back of the Sabo dam model. Different front inclination angles are set for each Sabo dam models. The time history of the impact load is examined by comparing the loads corresponding to four kinds of dams, which are different from the front inclination angles, and decrease of impact load considering the buffering effect of driftwoods in debris flow.

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