scholarly journals Time-Harmonic Response of an Elastic Pile in a Radially Inhomogeneous Poroelastic Medium

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Xibin Li ◽  
Wenhui Xu ◽  
Zhiqing Zhang
Keyword(s):  
Twist Angle ◽  
Engineering Practice ◽  
Zone Model ◽  
Poroelastic Medium ◽  
Soil System ◽  
Harmonic Response ◽  
Disturbed Soil ◽  
Time Harmonic ◽  
Radially Inhomogeneous ◽  
Surrounding Soil

The time-harmonic response of an elastic pile embedded in a radially inhomogeneous poroelastic medium and subjected to a torsional loading is studied in the present article. In engineering practice, the surrounding soil may be weakened due to the disturbance effect caused by pile driving. To simulate the weakened surrounding soil, a boundary zone model with the complex shear modulus of the inner disturbed soil changing in a parabolic form along the radial direction is proposed. In view of the axis-symmetric deformation of the surrounding soil under torsional load, the equation of motion of the saturated soil is solved in the cylindrical coordinate system. The vibration displacement and shear stress solutions for the inner disturbed soil are gained by expanding the displacement as a power series, and those for the outer undisturbed soil are obtained by solving the partial differential equation. By virtue of continuity conditions at the interface between inner and outer soil regions, the torsional impedance of the radially inhomogeneous soil is solved. Then, via the boundary and continuity conditions of the pile-soil system, the twist angle and torque of the pile are obtained in the frequency domain. Finally, selected numerical results are conducted to investigate the influence of the material damping, softening degree, and softening range of the inner soil on the distribution of the twist angle and torque of the pile along the depth direction.

scholarly journals Exact Solution for the Torsional Vibration of an Elastic Pile in a Radially Inhomogeneous Saturated Soil

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Xibin Li ◽  
Zhiqing Zhang ◽  
Jianchao Sheng
Keyword(s):  
Exact Solution ◽  
Torsional Vibration ◽  
Saturated Soil ◽  
Exponential Form ◽  
Soil System ◽  
Time Harmonic ◽  
Radial Inhomogeneity ◽  
Inner Region ◽  
Radially Inhomogeneous ◽  
Mathematical Derivation

An exact solution is proposed to study the time-harmonic torsional vibration of an elastic pile embedded in a radially inhomogeneous saturated soil. The radially inhomogeneous saturated soil is composed of inner disturbed and outer semi-infinite undisturbed concentric annular regions, with the shear modulus of the inner region changing in an exponential form along the radial direction. The governing equation of each region of the saturated soil is solved through rigorous mathematical derivation and the soil torsional impedance is derived with an exact and explicit expression. Making use of the boundary and continuity conditions of the pile-soil system, the torsional complex stiffness at the pile top is obtained in an exact closed form in the frequency domain. Selected numerical results are presented to investigate the influence of the radial inhomogeneity of the surrounding soil on the vibration characteristics of the pile-soil system.

scholarly journals Elastodynamics of radially inhomogeneous spherically anisotropic elastic materials in the Stroh formalism

2011 ◽  
Vol 468 (2138) ◽  
pp. 467-484 ◽  
Author(s):  
A. N. Norris ◽  
A. L. Shuvalov
Keyword(s):  
Displacement Field ◽  
Separation Of Variables ◽  
Transverse Isotropy ◽  
Stroh Formalism ◽  
Elastic Materials ◽  
Spherical Coordinate ◽  
Vector Spherical Harmonics ◽  
Time Harmonic ◽  
Anisotropic Elastic ◽  
Radially Inhomogeneous

A method for solving elastodynamic problems in radially inhomogeneous elastic materials with spherical anisotropy is presented, i.e. materials having c ijkl = c ijkl ( r ) in a spherical coordinate system { r , θ , ϕ }. The time-harmonic displacement field u ( r , θ , ϕ ) is expanded in a separation of variables form with dependence on θ , ϕ described by vector spherical harmonics with r -dependent amplitudes. It is proved that such separation of variables solution is generally possible only if the spherical anisotropy is restricted to transverse isotropy (TI) with the principal axis in the radial direction, in which case the amplitudes are determined by a first-order ordinary differential system. Restricted forms of the displacement field, such as u ( r , θ ), admit this type of separation of variables solution for certain lower material symmetries. These results extend the Stroh formalism of elastodynamics in rectangular and cylindrical systems to spherical coordinates.

scholarly journals Soil organic carbon along an altitudinal gradient in the Despeñaperros nature reserve, Southern Spain

2014 ◽  
Vol 6 (2) ◽  
pp. 2495-2521
Author(s):  
L. Parras-Alcántara ◽  
B. Lozano-García ◽  
A. Galán-Espejo
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Altitudinal Gradient ◽  
Nature Reserve ◽  
Regional Scale ◽  
C Sequestration ◽  
Organic Carbon Content ◽  
Soil System ◽  
Disturbed Soil ◽  
C Cycle

Abstract. Soil organic carbon (SOC) is extremely important in the global carbon (C) cycle as C sequestration in non-disturbed soil ecosystems can be a sink of C and mitigate greenhouse gas driven climate change. Soil organic carbon changes in space and time are relevant to understand the soil system and its role in the C cycle, and this is why the influence of topographic position on SOC should be studied. Seven topographic positions (toposequence) were analyzed along an altitudinal gradient between 607 and 1168 m.a.s.l. in the Despeñaperros nature reserve (Natural Park). At each study site, soil control sections (25 cm intervals) were sampled. The studied soils are mineral soils with > 3% organic carbon content. The main characteristic of the studied soils is SOC reduction with depth; these results were related to the gravel content and to the bulk density. The SOC on the surface was highly variable along the altitudinal gradient ranging between 27.3 and 39.9 g kg−1. The SOC stock (SOCS) in the studied area was influenced by the altitude, varying between 53.8 and 158.0 Mg ha−1. Therefore, the altitude factor must be considered in the SOCS estimation at local-regional scale.

scholarly journals Truffle Species Strongly Shapes Its Surrounding Soil Mycobiota in A Pinus armandii Forest

2020 ◽  
Author(s):  
Dong Liu ◽  
Mariana Herrera ◽  
Xinhua He ◽  
Jesús Perez-Moreno ◽  
Fuqiang Yu
Keyword(s):  
Chemical Analysis ◽  
Redundancy Analysis ◽  
Amplicon Sequencing ◽  
Species Variation ◽  
Ecological Functions ◽  
Soil System ◽  
Total N ◽  
Soil Systems ◽  
Shed Light ◽  
Surrounding Soil

Truffles contribute to crucial dynamics in the soil systems, being involved in plentiful ecological functions important for ecosystems. Despite this, the interactions between truffles and surrounding mycobiota remain unknown. Here, we aimed to shed light on how much truffle species could affect its surrounding soil mycobiota. Using traditional chemical analysis and Illumina ITS amplicon sequencing, we compared soil nutrients and mycobiota surrounding two truffle species: Tuber indicum (Ti) and T. pseudohimalayense (Tp) inhabit in the same Pinus armandii forest in southwestern China. Tp soil was more acidic and had higher nutrients (total C, N, P contents) than Ti soil. Fungal richness and diversity of truffle ascomata and surrounding soils were significantly higher in Tp than in Ti. Redundancy analysis showed relationships between soil fungal taxa and soil properties had changed from negative (Tp) to positive (Ti) and shifted from a moisture-driving (Tp) to a total N-driving (Ti). Overall, our results showed that the interactions between truffle and soil system had been altered with species variation, although the causative peculiarity of these associations needs to be further studied.

Time-harmonic response of a vertical crack in plates

1997 ◽  
Vol 27 (1) ◽  
pp. 21-28 ◽  
Author(s):  
K.Y. Lam ◽  
G.R. Liu ◽  
Y.Y. Wang
Keyword(s):  
Vertical Crack ◽  
Harmonic Response ◽  
Time Harmonic

Axisymmetric time-harmonic response of a surface-stiffened transversely isotropic half-space

Meccanica ◽  
2016 ◽  
Vol 52 (1-2) ◽  
pp. 183-196 ◽  
Author(s):  
Morteza Eskandari ◽  
Parham Samea ◽  
Seyed Farzad Ahmadi
Keyword(s):  
Half Space ◽  
Transversely Isotropic ◽  
Harmonic Response ◽  
Time Harmonic

scholarly journals Vertical Dynamic Impedance of Tapered Pile considering Compacting Effect

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Wenbing Wu ◽  
Guosheng Jiang ◽  
Bin Dou ◽  
Chin Jian Leo
Keyword(s):  
Soil Layer ◽  
Low Frequency ◽  
Vertical Vibration ◽  
Transfer Model ◽  
Soil System ◽  
Impedance Function ◽  
Dynamic Impedance ◽  
Tapered Pile ◽  
Transfer Method ◽  
Surrounding Soil

Based on complex stiffness transfer model, the vertical vibration of tapered pile embedded in layered soil is theoretically investigated by considering the compacting effect of the soil layer surrounding the tapered pile in the piling process. Allowing for the stratification of the surrounding soil and variable crosssection of the tapered pile, the pile-soil system is discretized into finite segments. By virtue of the complex stiffness transfer model to simulate the compacting effect, the complex stiffness of different soil segments surrounding the tapered pile is obtained. Then, substituting the complex stiffness into the vertical dynamic governing equation of tapered pile, the analytical solution of vertical dynamic impedance of tapered pile under vertical exciting force is derived by means of the Laplace technique and impedance function transfer method. Based on the presented solutions, the influence of compacting effect of surrounding soil on vertical dynamic impedance at the pile head is investigated within the low frequency range concerned in the design of dynamic foundation.

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