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Lu X.,PLA Air Force Aviation University | Xu J.,PLA Air Force Aviation University | Xu J.,Northwestern Polytechnical University | Ge H.,Air Force Engineering Design and Research Bureau | And 2 more authors.
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2010

Experiments of dynamic behaviors are carried out for sandstone specimens by split Hopkinson pressure bar (SHPB) equipment with confining pressure device at different confining pressures and different strain rates. The effects of strain rate on uniaxial dynamic compression strength and specific energy absorbency, as well as the mechanical characteristics of sandstone at the triaxial state under the circular action of impact loads are analyzed. It is demonstrated that the rates of dynamic and static Young's moduli increase evidently with values of 3.21-3.81. Dynamic Young's modulus increases slightly with the changes of strain rates, which ranges from 50 s-1 to 100 s-1. The linear relationships of specific energy absorbency and strain rate ε̇, dynamic strength increasing factor and strain rate ε̇(1/3) at the uniaxial state are all presented. It has clear brittle-ductile transformation(BDT) property for sandstone; and the stress-strain curve is shown under the yield platform at triaxial state. Along with the increase of circular action times of impact loads, the Young's modulus and the yield stress of specimens decrease, and the yield strain increases. The failure configurations of sandstone change with the confining pressure from axial tensile failure to compression-shear failure; and the critical confining pressure is 10 MPa. Specific energy absorbency value against lower confining pressure level is more than the value under higher confining pressure with the same energy of incident wave. The formulas among with the specific energy absorbency, the incident energy and confining pressure are put forward.


Yan Z.-X.,Lanzhou University | Yan L.,Xi'an Jiaotong University | Jiang P.,Lanzhou University | Wang H.-Y.,Air Force Engineering Design and Research Bureau
Zhendong yu Chongji/Journal of Vibration and Shock | Year: 2010

Blasting does work using explosion energy. It is a cheap and economical means of rock and soil excavation and widely used in ground and underground excavating engineering projects. Blast-induced ground vibration has harmful impacts on nearby structures and fields. The peak particle vibration velocity produced by ground vibration is commonly used to evaluate the risk of blast earthquake. There have been some empirical equations and methods to predict the peak ground vibration velocity, however, these equations are invalid when the specific conditions used for deduction can't be met. When blast earthquake wave propagates in rock and soil masses, ground vibration is complex and is influenced by many parameters. A discussion about the empirical equations and Fourmap method predicting the peak ground vibration velocity due to blasting was performed. Farther more, an attempt was made to predict the peak ground vibration velocity in blast earthquake by using an artificial neural network.


Lu X.-C.,PLA Air Force Aviation University | Xu J.-Y.,PLA Air Force Aviation University | Xu J.-Y.,Northwestern Polytechnical University | Zhao D.-H.,PLA Air Force Aviation University | And 2 more authors.
Gongcheng Lixue/Engineering Mechanics | Year: 2011

Dynamic mechanical performance experiments are carried out for sandstone specimens at different confining pressures and different strain rates by using the split Hopkinson pressure bar equipment with confining pressure device. The paper analyzes the relationship among the accumulative total of special energy absorbency, confining pressure, and damage of sandstone under the cyclical impact load. It is demonstrated that sandstone has BDT(brittle-ductile transformation) property, and the yield platform is observed in the stress-strain curve in triaxial state. Along with the increase of cycle numbers of impact load, the elastic modulus and the yield stress of specimen decrease, and the yield strain increases. Energy absorbency ratio increases with the augment of the strain rate, and decreases with the augment of confining pressure. When the confining pressure increases gradually, the increase rate of damage becomes slow along with the accumulative total of special energy absorbency. In summary, the higher confining pressure is, the more energy is needed for sandstone to reach the same damage level. Finally, the formulas are putted forward.


Yan Z.,Lanzhou University | Song Y.,Central South University of forestry and Technology | Jiang P.,Lanzhou University | Wang H.,Air Force Engineering Design and Research Bureau
Science China Technological Sciences | Year: 2010

The interaction between lateral root System of woody plant and soil mass is similar to the one between shrub, herbage and soil mass, and has the effect of frictional reinforcement on slope soil. It plays an important role in reinforcing soil strength in shallow slope. Therefore, slope soil mass can be considered as a composite of soil and plant roots and the soil strength and stability of shallow slope soil mass are improved. However, current researches still remain on the level of qualitatively analyzing the relation between root and soil mass. In this paper, some exploratory researches on quantitative analysis of the interaction mechanism between root and soil mass are conducted. With the study of interaction between herbage root System (lateral root System of woody plants) and soil mass, the mechanical model of interaction between frictional root and soil mass is established. The accuracy of the model is verified by field experiments of Pinus Yunnanensis. The mechanical model provides a crucial theoretical guidance to quantitatively analyzing the interaction between plant root and soil mass; it also has certain values in application. © 2010 Science China Press and Springer-Verlag Berlin Heidelberg.


Yan Z.,Lanzhou University | Yan C.,Central South University of forestry and Technology | Wang H.,Air Force Engineering Design and Research Bureau
Science China Technological Sciences | Year: 2010

The most basic function of slope vegetation is to strengthen rock and soil mass through plant roots which increase the shear strength of the slope markedly and thereby increase the stability of the slope. However, the calculation of the reinforcement ability of slope vegetation still remains at the stage of judging by experience, because it is rather difficult due to the intricacy and volatility of the force condition of plant roots in rock and soil medium. Although some scholars have tried to study the interaction between plant roots and soil mass, the systemic analysis of the mechanical reinforcement mechanism and the contribution of plant roots to strengthening the rock and soil mass on the surface of the slope is untapped. In this paper, by analyzing the mechanism of slope vegetation and the corresponding reinforcement effect, the effects that slope vegetation generates on the shear strength of slope soil mass are studied, thereby a theoretical basis for plant protection designing is provided. © 2010 Science China Press and Springer-Verlag Berlin Heidelberg.


Yan Z.-X.,Lanzhou University | Song Y.,Central South University of forestry and Technology | Jiang P.,Lanzhou University | Wang H.-Y.,Air Force Engineering Design and Research Bureau
Applied Mathematics and Mechanics (English Edition) | Year: 2010

With the help of plant roots, slope vegetation makes the slope soil mass become a composite material of soil and roots, and thus enhances shear strength of the slope soil mass and stability of the slope. However, the related studies at present are still qualitative. In this paper, quantitative analysis of the interaction between roots and soil mass are made. By the analysis of the interaction between herbaceous plant roots including lateral roots of woody plants and rock and soil mass, a mechanical model of the interaction between frictional roots and soil is established, and its correctness is shown. A mechanical model of the interaction between anchorage root, namely, woody plant taproot, and soil is also established. The establishment of the models provides a useful means in quantitative analysis of the interaction between plant roots and soil, and has practical values. © Shanghai University and Springer-Verlag Berlin Heidelberg 2010.


Yan Z.-X.,Lanzhou University | Duan J.,Lanzhou University | Wang H.-Y.,Air Force Engineering Design and Research Bureau
Meitan Xuebao/Journal of the China Coal Society | Year: 2010

According to the rule that rock mass structure plane and its shear strength properties were dominant in controlling the stability of rock slope, on the basis of rock mass structure plane network and its engineering boundary conditions, every possible slide path of rock slope was searched. By applying the theory of Lajtai and Einstein, Equivalent Mohr-Coulomb Yield Criterion, anti-slide force and sliding force of rock bridge and structure plane were calculated. Furthermore, got a rigorous formula for calculating safety coefficients; and moreover, skid-resisting reserve on each section of different slide paths and total skid-resisting reserve were ascertained. The comparative research of different slide path safety coefficients, total skid-resisting reserve and the density of total skid-resisting reserve was established. The research method for exploring dangerous slide path and stability of rock slope without obvious slip surface was studied. The example shows that applying safety coefficients and density of total skid-resisting reserve in assessing rock slope stability is feasible.


Yan Z.,Lanzhou University | Jiang P.,Lanzhou University | Wang H.,Air Force Engineering Design and Research Bureau
Advanced Materials Research | Year: 2012

The research deals with the issues and handling regarding the safety of complexlystructured round water pressure blast of cisterns, including calculating the safety-needed explosive quantity, explosive distribution mode, pre-treatment before the blast, safe construction and safe checking. The research specially focuses upon some safety issues and a general introduction to the safety measures to take in the project. Similar projects can also refer to it. © (2012) Trans Tech Publications, Switzerland.


Yan Z.-X.,Lanzhou University | Peng N.-B.,Lanzhou University | Jiang P.,Lanzhou University | Wang H.-Y.,Air Force Engineering Design and Research Bureau
Meitan Xuebao/Journal of the China Coal Society | Year: 2011

The vibration security issues and the methods of determining safety distance in blasting engineering projects were studied. Through applying structural dynamics and structural seismic principle, taking the peak velocity and the frequency of blasting-induced seismic wave into account, following the principle of discriminatively treating structural form and dynamic reaction characteristics, aiming at presently applied blasting safety regulation GB 6722-2003, the safety permission criteria and the safety distance of structural blasting vibration were investigated, the deficiency of regulation GB 6722-2003 was pointed out. Furthermore, the management and prediction of blasting-induced vibration strength were explored.


Yan Z.,Lanzhou University | Cai H.,Lanzhou University | Jiang P.,Lanzhou University | Wang H.,Air Force Engineering Design and Research Bureau
Advanced Materials Research | Year: 2011

Blast-induced seismic wave, which is an instantaneous, complicated wave, is different from natural seismic wave. It has characteristics such as high frequency, fast vibration intensity attenuation rate with distance increasing, short duration, generally small hypocenter energy and short wavelength of blast-induced seismic wave, etc. In this paper, on the basis of motion equation of the structural system and through rigorous mathematical induction under blast-induced seismic action, the energy transfer (input) and transformation equations of single freedom structural system and multiple freedom structural system are obtained and carefully studied. Through using stress-strain connection and the transmission characteristics of wave in different medium, the author explored the mechanism and time-space process of the action blast-induced seismic vibration has on structure. Meanwhile, the author also analyzed the impacts blast-induced seismic vibration characteristics and structure dynamic characteristics have on structural reaction. Furthermore, the mechanism of action blast-induced seismic vibration has on structure is revealed. © (2011) Trans Tech Publications, Switzerland.

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