scholarly journals On the inclusion of a velocity-dependent basal drag in avalanche models

1998 ◽  
Vol 26 ◽  
pp. 277-280 ◽  
Author(s):  
J.M.N.T. Gray ◽  
Y.C. Tai
Keyword(s):  
Stress State ◽  
Constant Coefficient ◽  
Dry Friction ◽  
Earth Pressure ◽  
Asymptotic Model ◽  
Drag Coefficients ◽  
Finite Velocity ◽  
Large Thickness ◽  
Coulomb Dry Friction ◽  
Avalanche Models

The Savage-Hutter model is generalized by including a velocity-dependent drag in addition to the usual Coulomb dry friction at the base of the avalanche. Both linear and quadratic velocity dependencies are considered, with either constant or asymptotically constant drag coefficients for large thickness h. The singular nature of the constant coefficient model for small h is demonstrated and it is shown that the asymptotic model allows the tail of the avalanche to move at a finite velocity. The inclusion of velocity drag changes the stress state in the avalanche and new earth-pressure relations are derived and investigated.

scholarly journals On the inclusion of a velocity-dependent basal drag in avalanche models

1998 ◽  
Vol 26 ◽  
pp. 277-280 ◽  
Author(s):  
J.M.N.T. Gray ◽  
Y.C. Tai
Keyword(s):  
Stress State ◽  
Constant Coefficient ◽  
Dry Friction ◽  
Earth Pressure ◽  
Asymptotic Model ◽  
Drag Coefficients ◽  
Finite Velocity ◽  
Large Thickness ◽  
Coulomb Dry Friction ◽  
Avalanche Models

The Savage-Hutter model is generalized by including a velocity-dependent drag in addition to the usual Coulomb dry friction at the base of the avalanche. Both linear and quadratic velocity dependencies are considered, with either constant or asymptotically constant drag coefficients for large thicknessh. The singular nature of the constant coefficient model for smallhis demonstrated and it is shown that the asymptotic model allows the tail of the avalanche to move at a finite velocity. The inclusion of velocity drag changes the stress state in the avalanche and new earth-pressure relations are derived and investigated.

Two-Frequency Oscillation With Combined Coulomb and Viscous Frictions

2002 ◽  
Vol 124 (4) ◽  
pp. 537-544 ◽  
Author(s):  
Gong Cheng ◽  
Jean W. Zu
Keyword(s):  
Steady State ◽  
Dry Friction ◽  
Single Frequency ◽  
Friction Oscillator ◽  
One Stop ◽  
Frequency Excitation ◽  
Stop Motion ◽  
The One ◽  
Coulomb Dry Friction ◽  
Mass Spring

In this paper, a mass-spring-friction oscillator subjected to two harmonic disturbing forces with different frequencies is studied for the first time. The friction in the system has combined Coulomb dry friction and viscous damping. Two kinds of steady-state vibrations of the system—non-stop and one-stop motions—are considered. The existence conditions for each steady-state motion are provided. Using analytical analysis, the steady-state responses are derived for the two-frequency oscillating system undergoing both the non-stop and one-stop motions. The focus of the paper is to study the influence of the Coulomb dry friction in combination with the two frequency excitations on the dynamic behavior of the system. From the numerical simulations, it is found that near the resonance, the dynamic response due to the two-frequency excitation demonstrates characteristics significantly different from those due to a single frequency excitation. Furthermore, the one-stop motion demonstrates peculiar characteristics, different from those in the non-stop motion.

scholarly journals THE REACTIVE CAPACITY OF THE SOIL BASES OF GRAVITY-TYPE QUAY WALL

World Science ◽  
2019 ◽  
Vol 1 (9(49)) ◽  
pp. 16-19
Author(s):  
Natela Khoneliia ◽  
Svetlana Bugaeva
Keyword(s):  
Stress State ◽  
Earth Pressure ◽  
Base System ◽  
Soil Base ◽  
Lateral Earth Pressure ◽  
Quay Wall ◽  
Wide Range ◽  
Reactive Capacity ◽  
Limit Stress ◽  
Foundation Structure

The results of studies of the reactive capacity of the soil base of a gravity- type quay-wall on the basis of the method developed for calculating the “structure - soil base” system are considered. The method proposed allows determining the reactive capacity of the soil base in conditions of mixed stress state model (limit and sublimit stress state of the soil base) under and around of the base of the foundation structure in a wide range of loads of lateral earth pressure. The transformation of limit and sublimit stress state zones of the soil base on the basis of numerical modeling is presented which shows an increase of the sizes of limit stress state and a decrease of the sizes of sublimit stress state.

scholarly journals DISSIPATIVE OSCILLATORS’ POWER CHARACTERISTIC NON-SYMMETRY DYNAMIC EFFECT

2021 ◽  
pp. 65-75
Author(s):  
Vasiliy Olshanskiy ◽  
Stanislav Olshanskiy
Keyword(s):  
Differential Equation ◽  
Dry Friction ◽  
Elastic Characteristic ◽  
Approximation Error ◽  
Dynamic Effect ◽  
Viscous Friction ◽  
Equation Of Motion ◽  
Lambert Function ◽  
Coulomb Dry Friction ◽  
Non Linear Oscillator

The features of motion of a non-linear oscillator under the instantaneous force pulse loading are studied. The elastic characteristic of the oscillator is given by a polygonal chain consisting of two linear segments. The focus of the paper is on the influence of the dissipative forces on the possibility of occurrence of the elastic characteristic non-symmetry dynamic effect, studied previously without taking into account the influence of these forces. Four types of drag forces are considered, namely linear viscous friction, Coulomb dry friction, position friction, and quadratic viscous resistance. For the cases of linear viscous friction and Coulomb dry friction the analytical solutions of the differential equation of oscillations are found by the fitting method and the formulae for computing the swings are derived. The conditions on the parameters of the problem are determined for which the elastic characteristic non-symmetry dynamic effect occurs in the system. The conditions for the effect to occur in the system with the position friction are derived from the energy relations without solving the differential equation of motion. In the case of quadratic viscous friction the first integral of the differential equation of motion is given by the Lambert function of either positive or negative argument depending on the value of the initial velocity. The elastic characteristic non-symmetry dynamic effect is shown to occur for small initial velocities, whereas it is absent from the system when the initial velocities are sufficiently large. The values of the Lambert function are proposed to be computed by either linear interpolation of the known data or approximation of the Lambert function by elementary functions using asymptotic formulae which approximation error is less than 1%. The theoretical study presented in the paper is followed up by computational examples. The results of the computations by the formulae proposed in the paper are shown to be in perfect agreement with the results of numerical integration of the differential equation of motion of the oscillator using a computer.

The Research on Earth Pressure behind Inclined Retaining Wall Considering Arching Effects

2013 ◽  
Vol 790 ◽  
pp. 410-413
Author(s):  
Jian Ming Zhu ◽  
Qi Zhao
Keyword(s):  
Stress State ◽  
Retaining Wall ◽  
Earth Pressure ◽  
Vertical Stress ◽  
Soil Arching ◽  
Active Pressure ◽  
Passive Pressure ◽  
The Earth ◽  
Two Factors

The earth pressure behind inclined wall considering the soil arching effects which was decided by two factors, the coefficient and average vertical stress, was necessary to research. Based on the analysis of stress state behind the retaining wall, the unified solution of active pressure and passive pressure was derived and was used to calculate both the magnitude and point of application. According to examples, as the angle of inclined retaining wall increasing which was signifying by , the arching effects would be also increasing which the soil was in the passive limit and be falling which the soil was in the active limit.

On the Pressure of Loose Material on the Bottom and Walls of a Drum

2014 ◽  
Vol 682 ◽  
pp. 375-379 ◽  
Author(s):  
Anton A. Kazantsev ◽  
S.V. Klishin ◽  
Alexander F. Revuzhenko
Keyword(s):  
Stress State ◽  
Discrete Element Method ◽  
Coordinate System ◽  
Dry Friction ◽  
Loose Material ◽  
Discrete Element ◽  
Filling Process ◽  
Element Method

Janssen problem of the loose material pressure on the drum bottom and walls was numerically investigated by discrete element method in 3D coordinate system. Dry friction of granulated material particles was taken into consideration as well as friction of drum walls. The effect of a filling process on the stress state of medium was demonstrated.

scholarly journals Optimization and Mechanical Characteristics of Spatial Arc Antislide Pile

2021 ◽  
Vol 2021 ◽  
pp. 1-18
Author(s):  
You-Sheng Deng ◽  
Cheng-Pu Peng ◽  
Jun-Cong Liu ◽  
Ling-Tao Li ◽  
Yun-Bo Fu
Keyword(s):  
Stress State ◽  
Mechanical Characteristics ◽  
Earth Pressure ◽  
Bending Moment ◽  
Test Results ◽  
Safety Factors ◽  
Supporting Structure ◽  
The Earth ◽  
Practical Engineering ◽  
Simulation Results

To improve the stress state of traditional antislide pile and utilize the stable soil on both sides of a landslide and slope foot, a spatial arc antislide pile supporting structure was proposed. Based on numerical calculation, a parametric study was conducted to assess the influence of the rise-span ratio on the stress state of the supporting structure, the displacement of the pile top, and the earth pressure in the front of the pile. The optimal rise-span ratio was 3-16 according to the numerical simulation results. An indoor model test at the optimal rise-span ratio was carried out, recording the pile strain and the earth pressure in front of the pile. The results showed that some indices increased with the increase in rise-span ratio, such as the load transferred to the pile at the arch foot, the bending moment of the piles, the displacement of the pile top, and the earth pressure; within a certain depth near the pile top, the soil in front of the pile is loose during the loading processes, and the earth pressure at the range was zero. The overall safety factors of the four supporting models were 2.42, 2.66, 2.78, and 2.84, respectively, which can satisfy the requirements for practical engineering. The test results verify the feasibility and rationality of the spatial arc antislide pile supporting structure, which can provide a new idea for landslide treatment.

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