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Sun M.-M.,Zhejiang Institute of Hydraulics and Estuary | Sun M.-M.,Zhejiang Provincial Key Laboratory of Hydraulics Disaster Prevention and Mitigation | Sun M.-M.,Zhejiang University | Xia T.-D.,Zhejiang University
Zhendong yu Chongji/Journal of Vibration and Shock | Year: 2014

A theoretical method for calculating the multiple scattering of P and SV waves by arbitrarily arranged and circular cross-sectional multi-row elastic piles barrier was presented to cover the shortage that single scattering hypothesis is reasonable only when the cross-sectional size is negligible compared with the incident wave length. In the method the interference phenomenon was considered as well. The direct scattering of P and SV waves by an arbitrary elastic pile was defined as the first order scattering, which was then regarded as the secondary wave source of the second order scattering and all the scatterers and successive orders would follow this multiple scattering process. Each order of scattering satisfies the condition of stress and displacement continuity at pile-soil interface and this leads to obtain an iteration relationship of wave functions. The total scattering wave field was achieved by composing all orders of scattering by scatterers. The influences of scattering orders, separations of piles, distances between pile-rows and shear modulus ratio of pile to soil etc. on isolation effectiveness of pile barriers were investigated. The results give a referred basis for vibration isolation design in practical engineering. Source


Sun M.-M.,Zhejiang Institute of Hydraulics and Estuary | Sun M.-M.,Zhejiang Provincial Key Laboratory of Hydraulics Disaster Prevention and Mitigation
Yantu Lixue/Rock and Soil Mechanics | Year: 2014

A theoretical methodology which can calculate multiple scattering of plane SH waves by arbitrarily arranged and configuration of multi-row tubular piles is achieved. It can be considered the commonly so-called single scattering as the first order of multiple scattering. The second order of scattering of certain tubular pile is derived from incident waves which are excited from the first order of scattering by all tubular piles, which are also be regarded as the secondary waves by the first scattering. The rest scattering process of multiple order can be considered in the same manner. Assuming that every scattering order at pile-soil interface and interior of tubular pile are satisfied the elastic boundary conditions, the incident, scattering and transmitted waves are expanded in wave functions with Graf's addition theorem so that the undetermined scattering (transmitted) complex coefficients are obtained. Theoretical solutions of total scattering and transmitted wave fields inside the tubular piles are achieved. The influences of multiple scattering orders, ratios of the pile radius and distance between piles (or pile rows), shear modulus ratios of pile and soil, ratios of internal and external radius of tubular piles, geometric parameters of multi-row tubular piles etc. on screening effectiveness is discussed with numerical examples. The results show that tubular piles can achieve better screening effects than solid piles do. Several valuable reference bases of engineering design with discontinuous barriers made by tubular piles are delivered consequently. Source


Li X.,Zhejiang Institute of Hydraulics and Estuary | Li X.,Zhejiang Provincial Key Laboratory of Hydraulics Disaster Prevention and Mitigation | Li H.,Zhejiang Institute of Hydraulics and Estuary | Li H.,Zhejiang Guangchuan Engineering Consulting Co. | And 2 more authors.
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2015

Crushing of the slag from Qincun Reservoir and the gravel-cobble from Yuxi Reservoir was studied by large-scale direct shear tests, and discarding parameters were introduced to investigate laws of breakage development from stratification planes of fractions and granular soil as a whole respectively. The results show that the relationship between discarding ratio Rk and nominal stress σ is linear for different fractions of the tested coarse-grained soils with σ varying in the research range. And difference of crushing of the two tested soils, which is mainly reflected in the grains from larger fractions, tends to disappear as grain size decreases. For coarse-grained soil as a whole, when σ varies in the range of 0-300 kPa, the breakage degrees of two soils are rather close. However, once σ varies in the range of 300-1 200 kPa, crushing of slags from Qincun Reservoir is more significant than gravel-cobble from Yuxi Reservoir. Besides, breakages of the two coarse-grained soils tend to be more remarkable as σ increases. ©, 2015, Academia Sinica. All right reserved. Source


Li X.,Zhejiang Institute of Hydraulics and Estuary | Li X.,Zhejiang Provincial Key Laboratory of Hydraulics Disaster Prevention and Mitigation | Li H.,Zhejiang Institute of Hydraulics and Estuary | Li H.,Zhejiang Guangchuan Engineering Consulting Co. | And 4 more authors.
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2016

Rockfill material shows obvious strength softening and dilantancy during shearing process, which can not be described effectively by the classic Duncan-Chang model. The better fitting results can be achieved by introducing modified Duncan-Chang model. The equation b-c=0.25 is given as judgment criterion of whether the material has softened or not. Particle breakage level is connected with material strength and deformation by introducing Hardin breakage index. The results show that with the breakage level increasing, the strength decreases obviously, while deformation mostly depends on confining pressure. Based on improved Duncan-Chang model, the relationship between dilatancy d and stress ratio η is given. Compared with existing theories, it shows more reasonable and convenient. © 2016, Science Press. All right reserved. Source


Sun M.-M.,Zhejiang University City College | Xia T.-D.,Zhejiang University | Chen X.-L.,Zhejiang Institute of Hydraulics and Estuary | Chen X.-L.,Zhejiang Provincial Key Laboratory of Hydraulics Disaster Prevention and Mitigation | And 8 more authors.
Shock and Vibration | Year: 2014

A new formal solution for the multiple scattering of plane harmonic waves by a group of arbitrary configuration tubular piles in an elastic total space is derived. Each order of scattering satisfies prescribed boundary conditions at the interface of tubular piles, which is delivered as the sum of incident and scattering waves. The first order performs the scattering wave by each scattered pile and the subsequent orders resulted from the excitation of each pile of first order of scattering from the remaining tubular piles. Advanced scattering orders can be regarded as the same manners. Several series of scattering coefficients are figured out with the aids of addition theorem so that the exact steady-state solution for the scattered displacement and stress is obtained. Particularly, when internal diameter of tubular piles tends to be infinitely small, it degenerates to a solid pile problem. By imposing the normalized displacement amplitudes and transmissibility indices, the influences of specific parameters such as scattering orders, internal and external diameter ratio of piles, pile material rigidity, position and distances between tubular pile and pile rows, and pile numbers are discussed. Certain recommended conclusions have been drawn as the guidelines of practical engineering design for discontinuous barrier of tubular piles. © 2014 Miao-miao Sun et al. Source

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