Dynamic stress state of underground pipelines at junctions

Abstract. Although slow-moving landslides represent a substantial hazard, their detailed mechanisms are still comparatively poorly understood. We have conducted a suite of innovative laboratory experiments using novel equipment to simulate a range of porewater pressure and dynamic stress scenarios on samples collected from a slow-moving landslide complex in New Zealand. We have sought to understand how changes in porewater pressure and ground acceleration during earthquakes influence the movement patterns of slow-moving landslides. Our experiments show that during periods of elevated porewater pressure, displacement rates are influenced by two components: first an absolute stress state component (normal effective stress state) and second a transient stress state component (the rate of change of normal effective stress). During dynamic shear cycles, displacement rates are controlled by the extent to which the forces operating at the shear surface exceed the stress state at the yield acceleration point. The results indicate that during strong earthquake accelerations, strain will increase rapidly with relatively minor increases in the out-of-balance forces. Similar behaviour is seen for the generation of movement through increased porewater pressures. Our results show how the mechanisms of shear zone deformation control the movement patterns of large slow-moving translational landslides, and how they may be mobilised by strong earthquakes and significant rain events.

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Effect of dynamic stress state perturbation on irreversible strain accumulation at interfaces in block-structured media

Physical Mesomechanics ◽

10.1134/s1029959916020041 ◽

2016 ◽

Vol 19 (2) ◽

pp. 136-148 ◽

Cited By ~ 25

Author(s):

A. S. Grigoriev ◽

E. V. Shilko ◽

S. V. Astafurov ◽

A. V. Dimaki ◽

E. M. Vysotsky ◽

...

Keyword(s):

Stress State ◽

Dynamic Stress ◽

Strain Accumulation ◽

Irreversible Strain ◽

Structured Media ◽

Block Structured

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STATIC STRAINING AND LONGITUDINAL OSCILLATIONS OF UNDERGROUND PIPELINE BUILT ON BLOCK FOUNDATION

PRECARPATHIAN BULLETIN OF THE SHEVCHENKO SCIENTIFIC SOCIETY Number ◽

10.31471/2304-7399-2020-1(59)-123-133 ◽

2021 ◽

pp. 123-133

Author(s):

A. B. Struk ◽

M. I. Vaskovskyi ◽

I. P. Shatskyi ◽

M. V. Makoviichuk

Keyword(s):

Steady State ◽

Stress State ◽

Differential Equations ◽

Analytical Solutions ◽

Equivalent Stress ◽

Forced Oscillations ◽

Underground Pipeline ◽

Underground Pipelines ◽

Block Foundation ◽

Static Tensile

The article considers the issues of forecasting the strength of underground pipelines, which are operated on seismically active sections of the route, composed of relatively rigid mobile blocks. According to the literature, the problems of the influence of the interaction of base faults on the stress state of the pipeline have not been studied to date. The aim of the work is to develop a model for the analysis of abnormal stresses in the underground pipeline on a damaged basis caused by static or time-harmonious mutual movement of its blocks along the axis of the pipe in the presence of several faults. Boundary value problems for differential equations of static tensile-compression and steady-state longitudinal oscillations of a tubular rod with discontinuous right-hand sides are formulated. Based on the analytical solutions of these problems for the cases of antisymmetric and symmetric displacement of the foundation blocks, the distributions of axial displacement and equivalent stress in the pipe, depending on the distance between faults and the frequency of forced oscillations, are investigated.

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Dynamic Stress Concentration at the Boundary of an Incision at the Plate Under the Action of Weak Shock Waves

Acta Mechanica et Automatica ◽

10.1515/ama-2017-0033 ◽

2017 ◽

Vol 11 (3) ◽

pp. 217-221 ◽

Cited By ~ 2

Author(s):

Olena Mikulich ◽

Vasyl’ Shvabyuk ◽

Heorhiy Sulym

Keyword(s):

Stress State ◽

Shock Waves ◽

Dynamic Stress ◽

Fourier Transforms ◽

Weak Shock ◽

Integral Equation Method ◽

Boundary Integral ◽

Dynamic Stresses ◽

Discrete Fourier Transforms ◽

Collocation Technique

AbstractThis paper proposes the novel technique for analysis of dynamic stress state of multi-connected infinite plates under the action of weak shock waves. For solution of the problem it uses the integral and discrete Fourier transforms. Calculation of transformed dynamic stresses at the incisions of plates is held using the boundary-integral equation method and the theory of complex variable functions. The numerical implementation of the developed algorithm is based on the method of mechanical quadratures and collocation technique. For calculation of originals of the dynamic stresses it uses modified discrete Fourier transform. The algorithm is effective in the analysis of the dynamic stress state of defective plates.

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