scholarly journals Wave Theory of Seismic Resistance of Underground Pipelines

2021 ◽  
Vol 11 (4) ◽  
pp. 1797
Author(s):  
Karim Sultanovich Sultanov ◽  
Nikolai Ivanovich Vatin
Keyword(s):  
Seismic Waves ◽  
Wave Theory ◽  
Contact Layer ◽  
Interaction Force ◽  
Seismic Wave Propagation ◽  
Seismic Resistance ◽  
Underground Pipeline ◽  
Soil Medium ◽  
Underground Pipelines ◽  
Peak Value

The object of the research is an underground straight horizontal pipeline subjected to seismic impact. The research method was analytical. The results were compared with the experimental results of other authors and computer calculations. It was shown that the main disadvantage of the dynamic theory of seismic resistance of underground pipelines is the neglect of the dynamic stress state in soil under seismic wave propagation. The next drawback of the dynamic theory is an inaccurate, approximate accounting for the displacement of the soil medium to which the underground pipeline is embedded. The complete interaction process includes the stages of nonlinear changes in the interaction force (the friction force) by manifesting its peak value and the Coulomb friction. The contact layer of soil undergoes shear deformations until complete structural destruction of the soil contact layer. The interaction force is the friction force, and its peak value does not appear. The seismic resistance of underground pipelines should be considered based on the theory of propagating seismic waves in a soil medium and the interaction of seismic waves with underground pipelines, i.e., based on the wave theory of seismic resistance of underground pipelines. A one-dimensional coupled problem of seismic resistance of underground pipelines under seismic impacts was posed based on the wave theory. An algorithm and a program for the numerical solution of the stated wave problems were developed using the method of characteristics and the method of finite differences. An analysis of the laws of interaction of underground pipelines with soil under seismic influences shows that it is necessary to use in the calculations the laws of interaction that account for the complete interaction processes observed in experiments. The analysis of the obtained numerical solutions and the posed coupled problems of the wave theory of seismic resistance of underground pipelines show the occurrence mechanisms of longitudinal stresses in underground pipelines under seismic influences. The results of calculations stated that an account for the dynamic stress normal to the underground pipeline’s outer surface leads to multiple increases in longitudinal stress in the underground pipeline. This multiple increase is due to the transformation of the interaction force into an active frictional force, resulting from a greater strain in soil than the one in the underground pipeline. Based on the analysis results, a theory of the seismic wave propagation process in an underground pipeline and surrounding soil was proposed.

scholarly journals Thickness dimensions of the contact layer of soil-rigid body interaction

2019 ◽  
Vol 97 ◽  
pp. 04040 ◽  
Author(s):  
Bakhtiyar Khusanov ◽  
Barno Rikhsieva
Keyword(s):  
Rigid Body ◽  
Structural Changes ◽  
Soil Layer ◽  
Contact Layer ◽  
Interaction Process ◽  
Soil Medium ◽  
One Dimensional ◽  
Underground Pipelines ◽  
The Finite Difference Method ◽  
Dimensional Statement

Solution of the problems of longitudinal interaction of underground pipelines with soil in a one-dimensional statement requires precise measurements of the thickness of the soil layer contacting with the pipeline. In order to determine the dimensions of the contact layer of soil, the behavior of soil medium under shear interaction of a rigid body with soil is studied. Under straining in soil medium, structural changes denoted by the coefficient of structural destruction are taken into account; the condition of complete adhesion is taken in the contact rigid body – soil boundary. The interaction process under consideration is investigated numerically by the finite difference method. The results of the calculations are presented in the form of graphs and are analyzed. From the obtained results, the maximum values of the thickness of soil contact layer are determined as well as the layers with the corresponding degree of structural destruction depending on the geometric dimensions of the rigid body.

scholarly journals Seismic wave propagation in anisotropic ice – Part 1: Elasticity tensor and derived quantities from ice-core properties

2015 ◽  
Vol 9 (1) ◽  
pp. 367-384 ◽  
Author(s):  
A. Diez ◽  
O. Eisen
Keyword(s):  
Seismic Waves ◽  
Dynamic Behaviour ◽  
Ice Core ◽  
Ice Cores ◽  
Seismic Wave Propagation ◽  
Elasticity Tensor ◽  
Reflection Coefficients ◽  
Seismic Velocities ◽  
Crystal Anisotropy ◽  
Elasticity Tensors

Abstract. A preferred orientation of the anisotropic ice crystals influences the viscosity of the ice bulk and the dynamic behaviour of glaciers and ice sheets. Knowledge about the distribution of crystal anisotropy is mainly provided by crystal orientation fabric (COF) data from ice cores. However, the developed anisotropic fabric influences not only the flow behaviour of ice but also the propagation of seismic waves. Two effects are important: (i) sudden changes in COF lead to englacial reflections, and (ii) the anisotropic fabric induces an angle dependency on the seismic velocities and, thus, recorded travel times. A framework is presented here to connect COF data from ice cores with the elasticity tensor to determine seismic velocities and reflection coefficients for cone and girdle fabrics. We connect the microscopic anisotropy of the crystals with the macroscopic anisotropy of the ice mass, observable with seismic methods. Elasticity tensors for different fabrics are calculated and used to investigate the influence of the anisotropic ice fabric on seismic velocities and reflection coefficients, englacially as well as for the ice–bed contact. Hence, it is possible to remotely determine the bulk ice anisotropy.

scholarly journals Vertical to Horizontal Spectral Ratio (VHSR) Response of Seismic Wave Propagation in a Homogeneous Elastic – Poroelastic Medium Using The Spectral Finite Element Method

2021 ◽  
Vol 11 (1) ◽  
pp. 95
Author(s):  
Sudarmaji Saroji ◽  
Budi Eka Nurcahya ◽  
Nivan Ramadhan Sugiantoro
Keyword(s):  
Finite Element Method ◽  
Elastic Medium ◽  
Seismic Waves ◽  
Low Frequency ◽  
Seismic Wave Propagation ◽  
P Wave ◽  
Poroelastic Medium ◽  
Compressional Waves ◽  
Spectral Finite Element Method ◽  
Spectral Finite Element

<p>Numerical modeling of 2D seismic wave propagation using spectral finite element method to estimate the response of seismic waves passing through the poroelastic medium from a hydrocarbon reservoir has been carried out. A hybrid simple model of the elastic - poroelastic - elastic with a mesoscopic scale element size of about 50cm was created. Seismic waves which was in the form of the ricker function are generated on the first elastic medium, propagated into the poroelastic medium and then transmitted to the second elastic medium. Pororoelastic medium is bearing hydrocarbon fluid in the form of gas, oil or water. Vertical and horizontal component of velocity seismograms are recorded on all mediums. Seismograms which are recorded in the poroelastic and second elastic medium show the existence of slow P compressional waves following fast P compressional waves that do not appear on the seismogram of the first elastic medium. The slow P wave is generated when the fast P wave enters the interface of the elastic - poroelastic boundary, propagated in the poroelastic medium and is transmited to the second elastic medium. The curves of Vertical to horizontal spectrum ratio (VHSR) which are observed from seismograms recorded in the poroelastic and the second elastic medium show that the peak of VHSR values at low frequency correlated with the fluid of poroelastic reservoir. The highest VHSR value at the low frequency which is recorded on the seismogram is above the 2.5 Hz frequency for reservoirs containing gas and oil in the second elastic medium, while for the medium containing water is the highest VHSR value is below the 2.5 Hz frequency.</p>

The Design and Establishment of 3D Urban Underground Pipeline Plan Aid System

2013 ◽  
Vol 475-476 ◽  
pp. 1546-1550
Author(s):  
Ying Chun Tao ◽  
Lian Zhao ◽  
Guo Jiang Zheng ◽  
Bo Gang Yang
Keyword(s):  
Decision Making ◽  
Normal Operation ◽  
Underground Pipeline ◽  
Planning Commission ◽  
Municipal Planning ◽  
Pipeline Network ◽  
Scene Graph ◽  
Underground Pipelines ◽  
The City ◽  
Modelling Process

Urban underground pipelines are the lifelines of the city. With the acceleration of city modernization, the traditional way to design and manage pipeline plans which relies on 2D diagrams has been difficult to secure the normal operation of the city. In this paper, a standard automatic 3D pipeline modelling process is proposed; a way to manage massive 3D scenes by scene graph is raised; three patterns of 3D integrated visualization are suggested; innovative stereo displays of pipeline analysis results are thought out. Eventually, a 3D urban underground pipeline plan aid system has been developed. At present, the system has been used in Xicheng Bureau of the Beijing Municipal Planning Commission, providing valuable decision-making information for urban underground pipeline network planning and management.

Method for laying underground pipelines taking into account the danger of landslide processes

2021 ◽  
pp. 16-20
Author(s):  
Хабиб Миргалиб оглы Насиров ◽  
Тофик Инаят оглы Сулейманов ◽  
Рамиз Ахмед оглы Эминов
Keyword(s):  
Calculation Method ◽  
Landslide Hazard ◽  
Low Risk ◽  
Segment Length ◽  
Underground Pipeline ◽  
Landslide Activity ◽  
Underground Pipelines ◽  
Landslide Processes ◽  
Pipeline Design

Известная расчетная методика оценки риска воздействия оползневых процессов на подземный трубопровод позволяет вычислить количество возможных утечек и поломок, исходно приняв данный риск равным для всех равноразмерных отрезков трубопровода. Однако на практике равная степень подверженности оползневой опасности участков трубопровода является исключением. Таким образом, возникает необходимость разработки новой методики расчета, предусматривающей реальные условия проектирования и эксплуатации трубопровода. Авторами определено условие, при котором подверженность трубопровода утечкам и разрывам в результате воздействия оползневых процессов может достигать максимальных значений. Сделан вывод о том, что для обеспечения разумной низкой величины риска следует избегать выполнения полученной зависимости. При этом должны быть соблюдены следующие условия: трасса разделена на неравные отрезки, с увеличением длины отрезка пиковая скорость грунта убывает (то есть более протяженные участки трубопровода следует располагать вдали от зон возможной активности оползневых процессов). The well-known calculation method for assessing the risk of landslide impact on an underground pipeline makes it possible to calculate the number of possible leaks and breakdowns, initially assuming an equal risk for all equally sized pipeline sections. However, in practice, equal exposure to landslide hazard of pipeline sections is an exception. Thus, there is a need to develop a new calculation method that provides for real conditions for pipeline design and operation. The authors determined the condition under which pipeline susceptibility to leaks and ruptures as a result of landslide impact can reach maximum values. It is concluded that in order to ensure a reasonably low risk value, the implementation of the resulting dependence should be avoided. In this case, the following conditions must be met: the route is divided into unequal segments, with an increase in segment length, the peak soil velocity decreases (that is, longer pipeline sections should be located away from possible landslide activity zones).

The Button Head Bullet Effects on the Incident Pulse of Split Hopkinson Press Bar

2015 ◽  
Vol 782 ◽  
pp. 311-315
Author(s):  
Jia Qu ◽  
Geng Chen ◽  
Guang Ping Zou
Keyword(s):  
Elastic Wave ◽  
Wave Length ◽  
Constant Strain Rate ◽  
Peak Stress ◽  
Wave Theory ◽  
Pulse Shaper ◽  
Lagrange Method ◽  
Stress Increase ◽  
Split Hopkinson ◽  
Peak Value

In order to make the specimen deformed under a constant strain rate and the stress in the specimen kept homogeneous, the wave shaper technology was adopted to modify the incidence waves of the normal Split Hopkinson Press Bar. A method of changing the shape of the bullet was suggested to be applied on the SHPB. Bullets with different length and different curvature have been researched in this paper. And the effection of the button head bullet about incidence pulse was simulated with Lagrange method by ANSYS/LS-DYNA. It is shown in the results that changing the curvature of the bullet impact the rising edge of incidence waves, and the peak stress increase with the speed of the bullet increase, the peak stress and length of incidence waves increased with the length of the button head bullet, when the peak stress reached a certain strength, increasing the bullet length could make the stress peak value lasted longer. Due to the reason that the button head bullet was based on the elastic wave theory, the wave length and the max stress of the shaped wave would be controlled conveniently and avoid the shortcoming that the analogue specimens could not be recycled in the normal pulse shaper technology.

Modelling the effects of diffusive-viscous waves in a 3-D fluid-saturated media using two numerical approaches

2020 ◽  
Vol 224 (2) ◽  
pp. 1443-1463
Author(s):  
Victor Mensah ◽  
Arturo Hidalgo
Keyword(s):  
Seismic Wave ◽  
Fourth Order ◽  
Seismic Waves ◽  
Time Discretization ◽  
Seismic Wave Propagation ◽  
Second Order ◽  
Finite Volume Scheme ◽  
Fluid Saturation ◽  
Runge Kutta ◽  
Saturated Medium

SUMMARY The accurate numerical modelling of 3-D seismic wave propagation is essential in understanding details to seismic wavefields which are, observed on regional and global scales on the Earth’s surface. The diffusive-viscous wave (DVW) equation was proposed to study the connection between fluid saturation and frequency dependence of reflections and to characterize the attenuation property of the seismic wave in a fluid-saturated medium. The attenuation of DVW is primarily described by the active attenuation parameters (AAP) in the equation. It is, therefore, imperative to acquire these parameters and to additionally specify the characteristics of the DVW. In this paper, quality factor, Q is used to obtain the AAP, and they are compared to those of the visco-acoustic wave. We further derive the 3-D numerical schemes based on a second order accurate finite-volume scheme with a second order Runge–Kutta approximation for the time discretization and a fourth order accurate finite-difference scheme with a fourth order Runge–Kutta approximation for the time discretization. We then simulate the propagation of seismic waves in a 3-D fluid-saturated medium based on the derived schemes. The numerical results indicate stronger attenuation when compared to the visco-acoustic case.

scholarly journals A Study on a Matching Algorithm for Urban Underground Pipelines

2019 ◽  
Vol 8 (8) ◽  
pp. 352
Author(s):  
Shuai Wang ◽  
Qingsheng Guo ◽  
Xinglin Xu ◽  
Yuwu Xie
Keyword(s):  
Blood Vessels ◽  
Underground Pipeline ◽  
Matching Algorithm ◽  
Partial Matching ◽  
Spatial Objects ◽  
Operation Efficiency ◽  
Geometric Similarity ◽  
Underground Pipelines ◽  
Pipeline Networks ◽  
Matching Performance

Urban underground pipelines are known as “urban blood vessels”. To detect changes in integrated pipelines and professional pipelines, the matching of same-name spatial objects is critical. Existing algorithms used for vector network matching were analyzed to develop an improved matching algorithm that can adapt to underground pipeline networks. Our algorithm improves the holistic matching of pipeline strokes, and also a partial matching algorithm is provided. In this study, appropriate geometric measures were selected to calculate the geometric similarity between pipeline strokes in their holistic matching. Existing methods for evaluating similarities in spatial scene structures in partial underground pipeline networks were improved. A method of partial matching of strokes was additionally investigated, and it compensates for the deficiencies of holistic stroke matching. Experiments showed that the matching performance was good, and the operation efficiency was high.

scholarly journals 2D full-waveform modeling of seismic waves in layered karstic media

Geophysics ◽  
2016 ◽  
Vol 81 (2) ◽  
pp. T25-T34 ◽  
Author(s):  
Yingcai Zheng ◽  
Adel H. Malallah ◽  
Michael C. Fehler ◽  
Hao Hu
Keyword(s):  
Seismic Waves ◽  
Finite Size ◽  
Spectral Element ◽  
Seismic Wave Propagation ◽  
Complex Model ◽  
Waveform Modeling ◽  
Frequency Space ◽  
Full Waveform ◽  
Matrix Scheme ◽  
Element Method

We have developed a new propagator-matrix scheme to simulate seismic-wave propagation and scattering in a multilayered medium containing karstic voids. The propagator matrices can be found using the boundary element method. The model can have irregular boundaries, including arbitrary free-surface topography. Any number of karsts can be included in the model, and each karst can be of arbitrary geometric shape. We have used the Burton-Miller formulation to tackle the numerical instability caused by the fictitious resonance due to the finite size of a karstic void. Our method was implemented in the frequency-space domain, so frequency-dependent [Formula: see text] can be readily incorporated. We have validated our calculation by comparing it with the analytical solution for a cylindrical void and to the spectral element method for a more complex model. This new modeling capability is useful in many important applications in seismic inverse theory, such as imaging karsts, caves, sinkholes, and clandestine tunnels.

Structure and mobility of the crust and mantle in the vicinity of island arcs

1968 ◽  
Vol 5 (4) ◽  
pp. 985-991 ◽  
Author(s):  
Jack Oliver ◽  
Bryan Isacks
Keyword(s):  
Upper Mantle ◽  
Seismic Waves ◽  
Current Knowledge ◽  
Average Rate ◽  
Seismic Wave Propagation ◽  
Rift System ◽  
Island Arcs ◽  
Deep Earthquake ◽  
Anomalous Zone ◽  
The World

A detailed study of seismic wave propagation in the Fiji-Tonga region shows that there exists in the upper mantle an anomalous zone whose thickness is about 100 km and whose upper surface is approximately defined by the zone of seismic foci extending to depths of about 700 km. Attenuation of seismic waves within the zone is anomalously low and velocities are high. Other island arcs appear to be associated with similar zones.The anomalous zone in Tonga can be interpreted as the westernmost portion of a block of lithosphere that has been thrust, or dragged, or has settled beneath the island arc. Such mobility of the lithosphere suggests a key role in geotectonics for this layer of strength and raises a number of possible new solutions to long standing problems. For example, assuming that deep earthquake zones throughout the world are a measure of the amount of underthrusting during the last 107 years, an average rate of spreading over the entire worldwide rift system can be obtained as a check, but not a proof, of the hypothesis. The half-velocity obtained is 1.3 cm/year and is reasonable in light of current knowledge.

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