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Wyświetlanie 1-5 z 5
Tytuł:
Experimental study of compressive failure of concrete under static and dynamic loads
Autorzy:
Liu, L.
An, H. M.
Powiązania:
https://bibliotekanauki.pl/articles/230225.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
beton
wytrzymałość na ściskanie jednoosiowe
dynamiczne ładowanie
szybkość odkształcania
pęknięcie
fragmentacja
concrete
uniaxial compressive strength
dynamic load
strain rate
fracture
fragmentation
Opis:
The fracture and fragmentation of concrete under static and dynamic loads are studied. The uniaxial compressive strength test is employed to study the concrete behavior under static loads while the split Hopkinson pressure bar is used to study the dynamic behavior of the concrete under static loads. The theories for acquiring the stress, strain and strain rate of the concrete in the dynamic test by Hopkinson pressure bar has been introduced. The fracture patterns of the concrete in the uniaxial compressive test have been obtained and the static concrete compressive strengths have been calculated. The fracture patterns of the concrete in the uniaxial compressive test have been obtained and the static concrete compressive strengths have been calculated. The fracture and fragmentation of the specimen under dynamic loads have been acquired and the stress-strain curves of concrete under various impact loads are obtained. The stress-strain curve indicates a typical brittle material failure process which includes existing micro-fracture closure stage, linear-elastic stage, nonlinear-elastic stage, and post-failure stages. The influence of the loading rate for the compressive strength of the concrete has compared. Compared with the concrete under static loads, the dynamic loads can produce more fractures and fragments. The concrete strength is influenced by the strain rate and the strength increases almost linearly with the increase of the strain rate.
Źródło:
Archives of Civil Engineering; 2020, 66, 3; 427-441
1230-2945
Pojawia się w:
Archives of Civil Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical study of dynamic behaviors of concrete under various strain rates
Autorzy:
An, H. M.
Liu, L.
Powiązania:
https://bibliotekanauki.pl/articles/230844.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
zachowanie dynamiczne
beton
model Holmquist-Johnson-Cook
HJC
pasek ciśnienia Hopkinsona rozdzielony
SHPB
pęknięcie
podział
dynamic behavior
concrete
Holmquist-Johnson-Cook model
split Hopkinson pressure bar
fracture
fragmentation
Opis:
As the dynamic behavior of the concrete is different from that under static load, this research focuses on the study of dynamic responses of concrete by simulating the split Hopkinson pressure bar (SHPB) test. Finite element code LS-DYNA is used for modeling the dynamic behaviors of concrete. Three continuous models are reviewed and the Holmquist-Johnson-Cook model (HJC) is introduced in detail. The HJC model which has been implemented in LS-DYNA is used to represent the concrete properties. The SHPB test model is established and a few stress waves are applied to the incident bar to simulate the dynamic concrete behaviors. The stress-strain curves are obtained. The stress distributions are analyzed. The crack initiation and propagation process are described. It is concluded that: the HJC model can modeling the entire process of the fracture initiation and fragmentation; the compressive of the concrete is significantly influenced by the strain rates.
Źródło:
Archives of Civil Engineering; 2019, 65, 4; 21-36
1230-2945
Pojawia się w:
Archives of Civil Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Experimental study of the effect of rock blasting with various cutting forms for tunnel excavation using physical model tests
Autorzy:
An, Huaming
Song, Yushan
Yang, Deqiang
Powiązania:
https://bibliotekanauki.pl/articles/1852379.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
wysadzanie skał
cięcie strumieniowe
pęknięcie
forma cięcia
model fizyczny
wykop tunelu
rock blasting
cutting blasting
fracture
cutting form
physical model
tunnel excavation
Opis:
Cutting blasting has been widely used for tunnel excavation. The cutting forms significantly influence the blasting effect. This research focuses on the study of the relationship between cutting forms and blasting effects. Similarity theory is proposed for the experimental study of the rock blasting using small models. Then four experimental modes with different cutting forms are used to study the blasting effect due to the cutting forms. The cutting depth, borehole utilization rate, fragments volume, and average fragment size are analysed. The blasting effects with various cutting forms are compared. The influences of the borehole space and the blasting delay are discussed. It is concluded that the spiral cutting form can produce more fragments and is recommend for the small section tunnel excavation.
Źródło:
Archives of Civil Engineering; 2021, 67, 3; 599-618
1230-2945
Pojawia się w:
Archives of Civil Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of projection pursuit regression model for blasting vibration velocity peak prediction
Autorzy:
Shi, Jianjun
An, Huaming
Wei, Xin
Powiązania:
https://bibliotekanauki.pl/articles/1852582.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
wibracje wybuchowe
przewidywanie
prędkość drgań
model regresji
pościg projekcji
płytki tunel
algorytm genetyczny
blasting vibration
vibration velocity
prediction
projection pursuit
regression model
shallow tunnel
genetic algorithm
Opis:
Based on Projection Pursuit Regression Theory (PPRT), a projection pursuit regression model has been established for forecasting the peak value of blasting vibration velocity. The model is then used to predict the peak value of blasting vibration velocity in a tunnel excavation blasting in Beijing. In order to train and test the model, 15 sets of measured samples from the tunnel project are used as the input data. It is found that predicting results by projection pursuit regression model on the basis of the input data is much more reasonable than that predicted by the traditional Sodaovsk algorithm and modified Sodaovsk formula. The results show that the average predicting error of the projection pursuit regression model is 6.36%, which is closer to the measured values. Thus, the projection pursuit prediction model is a practical and reasonable tool for forecasting the peak value of blasting vibration velocity.
Źródło:
Archives of Civil Engineering; 2021, 67, 2; 653-673
1230-2945
Pojawia się w:
Archives of Civil Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of positive elevation effect and prediction of vibration velocity of bench blasting vibration
Autorzy:
Zhang, X. J.
An, H. M.
Powiązania:
https://bibliotekanauki.pl/articles/1853676.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
drgania wybuchowe
efekt podniesienia pozytywny
formuła kroku
strzał
kopalnia
blasting vibration
positive elevation effect
step formula
mine
blasting
Opis:
Accurate prediction of blasting vibration should be achieved in mine blasting production practice. It is also a critical problem in the field of blasting vibration control technology research. In this research paper, on the basis of the previous research results and taking account into the reflection principle of elastic wave at the free interface, the authours proposes the blasting seismic wave propagation model. In addition, the blasting positive elevation effect are theoretically explained in detail, and the vibration velocity prediction formula of the positive elevation effect is derived. Finally, the positive elevation effect mechanism and the step (positive) formula are calibrated based on the on-site monitoring data of blasting vibration of Qipanjing Jinou coal mine. In beirf, a theoretical basis is laid by this paper for similar blasting projects.
Źródło:
Archives of Civil Engineering; 2021, 67, 1; 599-618
1230-2945
Pojawia się w:
Archives of Civil Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-5 z 5

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