Seismological Bureau of Zhejiang Province

Hangzhou, China

Seismological Bureau of Zhejiang Province

Hangzhou, China
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Huang B.,Zhejiang University | Xia T.,Zhejiang University | Qiu H.,Zhejiang University | Zhou X.,Seismological Bureau of Zhejiang Province | Chen W.,Nanjing University of Technology
Wave Motion | Year: 2017

Since the shear waves involved in in-situ and laboratory measurement methods vary significantly in terms of the frequency range, it is necessary to consider the effects of frequency on the shear wave velocity. In this study, sand particles are assumed to be spherical solid particles with an equal radius and identical material properties, and sand skeletons are regarded as granular aggregations generated through the random packing of sand particles. It is also assumed that the sand particles only undergo elastic deformation during shear wave propagation. Based on a spherical particle model, a formula is obtained for calculating the shear wave velocity in sand, with the shear wave frequency as an extra influencing parameter. The quantitative calculations demonstrate that the shear wave velocity decreases with an increase of sand porosity, and accelerates with increases of vertical effective stress and elastic modulus of the sand particles. It is also indicated that both the particle density and Poisson's ratio of the sand particles have negligible effects on the shear wave propagation. The frequency dispersion characteristics of shear wave propagating in sand are also discussed. Moreover, the critical frequency is defined and its analytical expression is derived. The calculation results obtained using the proposed equations agree well with the in-situ measurement results and bender element test data. © 2017 Elsevier B.V.


Xu P.,Zhengzhou University | Xu P.,CAS Wuhan Institute of Rock and Soil Mechanics | Li X.-C.,CAS Wuhan Institute of Rock and Soil Mechanics | Zhou X.-M.,Seismological Bureau of Zhejiang Province
Yantu Lixue/Rock and Soil Mechanics | Year: 2015

The coal-rocks contain gas are assumed as gas saturated isotropic homogeneous media. The physical equations, geometric equations, continuity equations and dynamic control equations about the coal-rocks are established using the mixture theory. The length of the gas suction hole is much larger than the diameter. The dynamic response of gas suction hole in the coal-rock due to the action of negative suction pressures during the suction process can be simplified into a two-dimensional initial-boundary problem. The theoretical solutions in frequency domain and time domain are respectively derived with Laplace transform and inverse Laplace transform. The parameters of coal rocks and gas in a mine of Henan province are taken as examples. The dynamic response near the hole wall is numerically calculated. The dimensionless radial displacements, radial stresses and circumferential stresses are analyzed. Finally, some conclusions are drawn as follows. The dimensionless radial displacements and stresses are mainly concentrated at a local area near the gas suction hole. The area increases with the suction time. Large and volatile circumferential stresses are generated at the hole wall. They increase as the negative suction pressures increase. ©, 2015, Academia Sinica. All right reserved.


Chen W.-Y.,Zhejiang University | Xia T.-D.,Zhejiang University | Liu Z.-J.,Zhejiang University | Zhou X.-M.,Seismological Bureau of Zhejiang Province
Zhendong yu Chongji/Journal of Vibration and Shock | Year: 2013

The unsaturated poroelasticity theory was used to describe the propagation characteristics of elastic waves in unsaturated soil, and the reflection problem of plane-S-waves at the free boundary of unsaturated soil was analyzed. According to the boundary conditions, the theoretical expressions of amplitude reflection ratios and energy reflection ratios for the four reflected waves including reflected P1 wave, reflected P2 one, reflected P3 one and reflected S one at the boundary were respectively derived and the numerical calculations were then performed. The effects of incident angle of plane-S-waves and saturation level of soil layer on the amplitude reflection ratios and energy reflection ratios of the four reflected waves were discussed in numerical examples. It was shown that amplitude reflection ratios and energy reflection ratios of various reflected waves are influenced by not only incident angle but also saturation level. The results were useful for the theoretical study on soil dynamics and the related seismic exploration projects.


Xu P.,Zhengzhou University | Zhou X.,Seismological Bureau of Zhejiang Province | Xia T.,Zhejiang University
Disaster Advances | Year: 2012

The amended Biot model of wave motion and the expansion method of wave functions are adopted, the scattering problem of a circular lining deeply buried in saturated soils by incident shear waves is studied, dynamic stress concentration factor (SCDF) at inner side of the lining and pore pressure concentration factor (pf*) at the boundary between the lining and saturated soils are analyzed and some important conclusions are obtained. The curves of SCDF and pf* are smooth and nearly not influenced by the lining's thickness when the incident frequencies of shear waves are lower, while the curves of SCDF and pf* have concave and convex parts and SCDF and pf* decrease when the lining's thickness increase and the incident frequencies of shear waves are higher.


Huang B.,Zhejiang University | Xia T.,Zhejiang University | Zhou X.,Seismological Bureau of Zhejiang Province | Liu Z.,Zhejiang University
Zhongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Central South University (Science and Technology) | Year: 2016

Based on the macroscopic equivalent model and microscopic contact theories, the shear wave velocity was studied. Considered as a kind of homogeneous, continuous and isotropic media macroscopically, the sand was assumed microscopically as an aggregate of randomly packed uniform equivalent spheres with the same material properties. Then, the formulas of the equivalent shear modulus and shear wave velocity in sand were derived by using particle contact theory and by introducing the correcting coefficient of the granule shape. The main influencing factors were analyzed through quantitative calculations. The results indicate that the shear wave velocity is mainly influenced by void ratio, elastic modulus of sand granule, burial depth and the correcting coefficient of the granule shape, while it is hardly influenced by inner friction angle, Poisson's ratio of sand granule, density of the sand and the constant connected with the coordination number. Through comparison, the calculation results using the present formulas agree well with measured data so as to verify the validity of the proposed method. © 2016, Central South University Press. All right reserved.


Shi S.Z.,Seismological Bureau of Zhejiang Province | Xu P.,Zhengzhou University
Recent Advances in Environmental Vibration - Proceedings of 6th International Symposium on Environmental Vibration, ISEV 2013 | Year: 2013

As a new type rubber isolator, the SBS modified asphalt pad is designed to the brick masonry rural residential building in Zhejiang Ping-hu County. In order to analyze the performance and isolation effect of the rubber isolators, a series of tests are made. The results show that the horizontal and vertical acceleration are all decreased, the damping of the building is increased, and the characteristic frequency of the whole building is lowered. Using the rubber isolator, the building seismic performance has excellent improvement. The SBS modified asphalt isolation pad is very suitable for the residential constructions widely distributed in the towns and villages in China.


Chen W.-Y.,Nanjing University of Technology | Chen W.-Y.,Zhejiang University | Xia T.-D.,Zhejiang University | Huang R.,Zhejiang University | Zhou X.-M.,Seismological Bureau of Zhejiang Province
Gongcheng Lixue/Engineering Mechanics | Year: 2013

The unsaturated soil is the most common nature soil form on the earth's surface, unlike the fully saturated soil, four bulk waves exist in this soil: one shear wave (i.e., S wave) and three compressional waves (i.e., P1 wave, P2 wave, P3 wave). Among these four type waves, P1 wave is the wave with fastest wave velocity and lowest attenuation coefficient, which is similar to the fast compressional wave in fully saturated soil. Hence the unsaturated poroelasticity theory is used to describe the propagation characteristics of elastic waves in unsaturated fluid-saturated soils, and the reflection problem of plane-P1-waves at the free boundary of unsaturated soils is analyzed. Based on the boundary conditions, the theoretical expressions of the amplitude reflection coefficients and energy reflection coefficients for the four reflected waves at the boundary, i.e., reflected P1 wave, reflected P2 wave, reflected P3 wave and reflected S wave, are respectively derived and the numerical calculations are then carried out. The effects of the incident angle and saturation degree of the soils on the amplitude reflection coefficients and energy reflection coefficients of the four reflected waves are discussed in the numerical example. It is shown that the amplitude reflection coefficients and energy reflection coefficients of the waves is effected by not only the incident but also the saturation degree. These conclusions are useful for the theoretical research and seismic exploration projects.


Xia T.-D.,Zhejiang University | Liu Y.,Zhejiang University | Wu M.,Zhejiang University | Zhou X.-M.,Seismological Bureau of Zhejiang Province
Harbin Gongye Daxue Xuebao/Journal of Harbin Institute of Technology | Year: 2011

Assuming deep buried sand is an aggregate of randomly packed uniform spheres, the equivalent shear modulus and the formula of shear wave velocity (Vs) in sand media were derived based on the the spheres-contact theory and the research results of microscopic particles elasticity. Seven influencing factors were analyzed, including porosity, saturation, internal friction angle, soil grain density, magnitude of stress, elastic modulus of sand grain and Poisson ratio of sand grain. The results were compared with the measured data, and the calculated value of Vs were generally in good agreement with the measured values. This study indicates that the value of Vs is mainly influenced by porosity, magnitude of stress and the elastic modulus of sand grain, and the shear wave velocity increases with the increasing of stress in high stress state, especially after the degree of density achieves 100%.


Liu Z.,Hangzhou Dianzi University | Zhou X.,Seismological Bureau of Zhejiang Province
ICCASM 2010 - 2010 International Conference on Computer Application and System Modeling, Proceedings | Year: 2010

Graphics cluster based parallel rendering has been widely used in computer aided design, scientific visualization, geometry scene rendering, virtual reality and so on. The key to high performance on graphics cluster is rendering task distribution strategy. According to multi-stream based data organization in Direct3D, this paper has presented sort-first multi-steam based rendering task distribution algorithm. Our algorithm includes three main steps that is data parsing, data distribution and data rematching. Experimental results have demonstrated that our algorithm can promote rendering performance to a great extent running on graphics cluster.

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