The Behavior of a Poroelastic Seabed Under Normal and Shear Loads

1989 ◽  
Vol 111 (4) ◽  
pp. 303-310
Author(s):  
G. C. W. Sabin
Keyword(s):  
Normal Stress ◽  
Normal Load ◽  
Extended Period ◽  
Offshore Structures ◽  
Theoretical Discussion ◽  
Shear Loads ◽  
Pore Pressure Response ◽  
Limiting Case ◽  
Poroelastic Seabed ◽  
Parameters Of Interest

One of the effects of ice and water forces on large offshore structures which rest on the seabed is to transmit surface tractions to the region of contact. A recent paper by Sabin and Raman-Nair [1] has examined the effect of a normal axisymmetric load P(r, t) on a poroelastic seabed under several different conditions of boundary permeabilities. That study provided a number of general formulas for an arbitrary normal load. The present paper extends the results found in [1] to include shear tractions. While reference [1] was primarily a theoretical discussion, the present paper examines several specific forms of loading and presents graphs showing the normal stress and pore pressure response for various values of the parameters of interest. These results are compared with the limiting case of an extended period of time.

scholarly journals Empirical Studies of Ice Sliding

1979 ◽  
Vol 23 (89) ◽  
pp. 157-170 ◽  
Author(s):  
W. F. Budd ◽  
P. L. Keage ◽  
N. A. Blundy
Keyword(s):  
Shear Stress ◽  
Normal Stress ◽  
Sliding Friction ◽  
Normal Load ◽  
Water Pressure ◽  
Empirical Studies ◽  
Shear Stresses ◽  
Friction Characteristic ◽  
Wide Range ◽  
Static Shear

AbstractAn experimental programme has been carried out for studying temperate-ice sliding over rock surfaces with a wide range of roughnesses, for normal and shear stresses comparable to those expected under real ice masses. The limiting static shear stress for acceleration has been found to be directly proportional to the normal load giving a constant limiting coefficient of static friction characteristic of the surface. For a constant applied normal stress N and shear stress τb, well below the limiting static shear, a steady velocity Vb results which increases approximately proportionally to τb and decreases with increasing N and the roughness of the surface. For high normal stress the velocity becomes approximately proportional to the shear stress cubed and inversely proportional to the normal stress. As the shear stress increases acceleration sets in, which, for different roughness and normal loads, tends to occur for a constant value of the product τbVb. For some surfaces at high normal loads this acceleration was retarded by erosion. For constant-applied-velocity tests a steady shear stress resulted, which tended to become constant with high velocities, and which increased with increasing normal stress but with a reduced coefficient of sliding friction. The relevance of the results to the sliding of real ice masses is discussed with particular reference to the importance of the effect of the relative normal stress, above basal water pressure, to the sliding rate.

End Effects in Laminated Anisotropic Beams — Part I

1995 ◽  
Vol 117 (4) ◽  
pp. 279-284
Author(s):  
J. A. Ackermann ◽  
T. J. Kozik
Keyword(s):  
Stress Field ◽  
Normal Stress ◽  
Transverse Shear ◽  
Analytical Method ◽  
Normal Load ◽  
End Effects ◽  
Laminated Beam ◽  
Simply Supported ◽  
Combination Of Material

The derivation of an analytical method to examine the stress field near the end of a simply supported, laminated beam is presented. Specific effort has been directed to accurately calculate the transverse-shear and normal stress by incorporating the exact displacement relations derived, by Kozik (1970). The method accommodates any combination of material lay-up and any type of normal load on the upper and lower surfaces. The reactions at the ends of the beam may be distributed over the surface edges in a fashion most accurately characterizing the physical supports. The solution and application of the method is presented in Part II of this paper.

Buckling of Simply Supported Plates Tapered in Planform

1956 ◽  
Vol 23 (2) ◽  
pp. 207-213
Author(s):  
Bertram Klein
Keyword(s):  
Elastic Buckling ◽  
Axial Loads ◽  
Flat Plates ◽  
Buckling Loads ◽  
Simply Supported ◽  
Shear Loads ◽  
Limiting Case ◽  
The Given

Abstract Design curves are presented for determining the elastic buckling loads of simply supported flat plates of isosceles trapezoidal planform and loaded in compression along the parallel edges. Shear loads are assumed to act along the sloping edges so that any ratio of axial loads may act along the parallel edges of the given plate. Isosceles triangular plates are included as a special limiting case, and the range of the values of the various geometric and load parameters presented in the curves is considered large enough to cover practically all conditions of the type treated which are encountered in practice.

scholarly journals Excess pore pressure in a poroelastic seabed saturated with a compressible fluid

1994 ◽  
Vol 31 (6) ◽  
pp. 989-1003 ◽  
Author(s):  
Z.Q. Yue ◽  
A.P.S. Selvadurai ◽  
K.T. Law
Keyword(s):  
Pore Pressure ◽  
Fluid Pressure ◽  
Offshore Structures ◽  
Pore Fluid ◽  
Excess Pore Pressure ◽  
Soil Consolidation ◽  
Normal Surface ◽  
Compressible Pore Fluid ◽  
Poroelastic Seabed ◽  
Excess Pore

This paper presents an analytical investigation on the excess pore-fluid pressure in a finite seabed layer by taking into account the influence of a compressible pore fluid. The seabed layer is modeled as a poroelastic layer saturated with a compressible pore fluid and resting on a rough, rigid impermeable base. The surface of the poroelastic seabed layer is either completely pervious or completely impervious, and subjected to a normal surface traction induced by offshore structures. The paper presents analytical and numerical results to illustrate the time-dependent behaviour of excess pore pressure in the poroelastic seabed. The results demonstrate that the presence of a compressible pore fluid reduces the generation of excess pore pressure in the poroelastic seabed layer. Key words : excess pore pressure, poroelastic seabed layer, soil consolidation, compressible pore fluid, integral transforms.

Frictional Energy Dissipation in a Rough Hertzian Contact

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
D. Dini ◽  
D. A. Hills
Keyword(s):  
Normal Load ◽  
Hertzian Contact ◽  
Partial Slip ◽  
Energy Losses ◽  
Loading History ◽  
Load History ◽  
Frictional Energy ◽  
Shear Loads ◽  
Uniform Array ◽  
Frictional Energy Dissipation

The interfacial contact pressure and shear traction distributions are found for a sphere pressed onto an elastically similar half-space whose surface is populated by a uniform array of spherical asperities, when the normal load is constant and an oscillatory shear, less than that needed to cause sliding, is imposed. Details of the load history suffered by asperities in an outer sliding annulus and an inner disk, where they experience partial slip, are found, together with the effects of the roughness on the overall tangential compliance and the frictional energy losses. It is shown that for the example combination of parameters chosen, under light shear loads, the rough contact absorbs less energy than a smooth one subject to the same loading history, but that for larger shearing forces the reverse is true.

scholarly journals Dynamic Responses of a Multilayered Transversely Isotropic Poroelastic Seabed Subjected to Ocean Waves and Currents

2022 ◽  
Vol 10 (1) ◽  
pp. 73
Author(s):  
Xi Chen ◽  
Qi Zhang ◽  
Xiang Yuan Zheng ◽  
Yu Lei
Keyword(s):  
Young’S Modulus ◽  
Young's Modulus ◽  
Dynamic Stiffness ◽  
Transversely Isotropic ◽  
Ocean Waves ◽  
Offshore Structures ◽  
Dynamic Responses ◽  
Vertical Shear ◽  
Waves And Currents ◽  
Poroelastic Seabed

In this study, a semi-analytical solution to the dynamic responses of a multilayered transversely isotropic poroelastic seabed under combined wave and current loadings is proposed based on the dynamic stiffness matrix method. This solution is first analytically validated with a single-layered and a two-layered isotropic seabed and then verified against previous experimental results. After that, parametric studies are carried out to probe the effects of the soil’s anisotropic characteristics and the effects of ocean waves and currents on the dynamic responses and the maximum liquefaction depth. The results show that the dynamic responses of a transversely isotropic seabed are more sensitive to the ratio of the soil’s vertical Young’s modulus to horizontal Young’s modulus (Ev/Eh) and the ratio of the vertical shear modulus to Ev (Gv/Ev) than to the vertical-to-horizontal ratio of the permeability coefficient (Kv/Kh). A lower degree of quasi-saturation, higher porosity, a shorter wave period, and a following current all result in a greater maximum liquefaction depth. Moreover, it is revealed that the maximum liquefaction depth of a transversely isotropic seabed would be underestimated under the isotropic assumption. Furthermore, unlike the behavior of an isotropic seabed, the transversely isotropic seabed tends to liquefy when fully saturated in nonlinear waves. This result supplements and reinforces the conclusions determined in previous studies. This work affirms that it is necessary for offshore engineering to consider the transversely isotropic characteristics of the seabed for bottom-fixed and subsea offshore structures.

scholarly journals Elastodynamic Response of Thermal Laser Pulse in Micropolar Thermoelastic Mass Diffusion Medium

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Rajneesh Kumar ◽  
Arvind Kumar
Keyword(s):  
Laser Pulse ◽  
Normal Stress ◽  
Tangential Stress ◽  
Mass Concentration ◽  
Normal Load ◽  
Normal Mode Analysis ◽  
Relaxation Times ◽  
Mode Analysis ◽  
Inclined Load ◽  
Tangential Load

The present investigation deals with the deformation in micropolar thermoelastic diffusion medium due to inclined load subjected to thermal laser pulse. Normal mode analysis technique is used to solve the problem. The inclined load is assumed to be a linear combination of a normal load and a tangential load. The closed form expressions of normal stress, tangential stress, couple stress, temperature distribution, and mass concentration are obtained. A computer program has been developed to derive the physical quantities numerically. The variation of normal stress, tangential stress, coupled stress, temperature change, and mass concentration is depicted graphically to show the effect of relaxation times and mass concentration. Some particular cases of interest are deduced from the present investigation.

A Composite Plate Theory With Rotatory Inertia, Transverse Shear, and Normal Stress Effects

1991 ◽  
Vol 113 (2) ◽  
pp. 127-132 ◽  
Author(s):  
G. Z. Voyiadjis ◽  
P. D. Panera
Keyword(s):  
Normal Stress ◽  
Transverse Shear ◽  
Plate Theory ◽  
Composite Plates ◽  
Offshore Structures ◽  
Refined Theory ◽  
Normal Strain ◽  
Rotatory Inertia ◽  
Stress Effects ◽  
Transverse Normal Strain

A refined theory for the flexural motions of composite plates is presented. The theory incorporates rotatory inertia in addition to the influence of transverse normal strain, transverse normal stress, and transverse shear. This is of primary interest for the analysis of offshore structures as well as piping analysis. The classical wave propagation problem is used to test the proposed theory. The results indicate the influence of the transverse normal strain on the wave speed for large values of h/λ. The shear coefficient obtained from the proposed theory has a constant magnitude as opposed to the undetermined coefficient form in previous flexural motion formulations.

scholarly journals Empirical Studies of Ice Sliding

1979 ◽  
Vol 23 (89) ◽  
pp. 157-170 ◽  
Author(s):  
W. F. Budd ◽  
P. L. Keage ◽  
N. A. Blundy
Keyword(s):  
Shear Stress ◽  
Normal Stress ◽  
Sliding Friction ◽  
Normal Load ◽  
Water Pressure ◽  
Empirical Studies ◽  
Shear Stresses ◽  
Friction Characteristic ◽  
Wide Range ◽  
Static Shear

Abstract An experimental programme has been carried out for studying temperate-ice sliding over rock surfaces with a wide range of roughnesses, for normal and shear stresses comparable to those expected under real ice masses. The limiting static shear stress for acceleration has been found to be directly proportional to the normal load giving a constant limiting coefficient of static friction characteristic of the surface. For a constant applied normal stress N and shear stress τ b, well below the limiting static shear, a steady velocity Vb results which increases approximately proportionally to τ b and decreases with increasing N and the roughness of the surface. For high normal stress the velocity becomes approximately proportional to the shear stress cubed and inversely proportional to the normal stress. As the shear stress increases acceleration sets in, which, for different roughness and normal loads, tends to occur for a constant value of the product τ b Vb . For some surfaces at high normal loads this acceleration was retarded by erosion. For constant-applied-velocity tests a steady shear stress resulted, which tended to become constant with high velocities, and which increased with increasing normal stress but with a reduced coefficient of sliding friction. The relevance of the results to the sliding of real ice masses is discussed with particular reference to the importance of the effect of the relative normal stress, above basal water pressure, to the sliding rate.

Normal load moving on magneto-elastic transversely isotropic half-space with irregular and hydrostatic initial stress

2015 ◽  
Vol 23 (8) ◽  
pp. 1354-1373 ◽  
Author(s):  
AK Singh ◽  
KC Mistri ◽  
A Chattopadhyay
Keyword(s):  
Shear Stress ◽  
Normal Stress ◽  
Initial Stress ◽  
Half Space ◽  
Normal Load ◽  
Coupling Parameter ◽  
Moving Load ◽  
Transversely Isotropic ◽  
Elastic Coupling ◽  
Hydrostatic Initial Stress

The present paper investigates the effect of initial stress, irregularity depth, irregularity factor and magneto-elastic coupling parameter on the dynamic response due to a normal moving load with constant velocity on the free surface of an irregular magneto-elastic transversely isotropic half-space under the state of hydrostatic initial stress. The expressions for normal stress and shear stress are obtained in closed form analytically. The considerable effect of initial stress, irregularity depth, irregularity factor and magneto-elastic coupling parameter on normal stress and shear stress are computed numerically and depicted by means of graphs. Moreover, comparative study highlighting the effect of various types of irregularity viz. rectangular irregularity, parabolic irregularity and no irregularity on the normal stress and shear stress is a key feature of the study.

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