Acta Geotechnica

, Volume 6, Issue 1, pp 13–20

One-dimensional consolidation under haversine repeated loading with rest period

Research Paper

DOI: 10.1007/s11440-010-0132-1

Cite this article as:
Razouki, S.S. & Schanz, T. Acta Geotech. (2011) 6: 13. doi:10.1007/s11440-010-0132-1

Abstract

Presented in this paper is a study of the one-dimensional consolidation process under haversine repeated loading with and without rest period. The analysis was carried out using a hybrid coupled, analytical and numerical implicit finite difference technique. The rate of imposition of excess pore-water pressure was determined analytically, and the remaining part of the governing differential equation was solved numerically. The clay deposit considered was a homogeneous clay layer with permeable top and/or impermeable bottom hydraulic boundary conditions with constant coefficients of permeability and of consolidation. The study reveals that although the loading function is positive for all times, the excess pore-water pressure at the base of the clay deposit with permeable top and impermeable bottom oscillates with time reaching a ‘steady state’ after few cycles of loading depending on whether there is a rest period or not. An increase in the rest period causes a decrease in the number of cycles required to achieve the steady state. The paper shows also that the rest period in the haversine repeated loading decelerates the consolidation process. Similarly, the paper reveals that the effective stress at the bottom of the clay layer with permeable top and impermeable bottom increases with time but showing mild fluctuations that do not change the sign. The maximum positive effective stress achieved depends on the rest period of the haversine repeated loading. A haversine repeated loading without a rest period gives the highest value for the positive effective stress.

Keywords

ConsolidationHaversine repeated loadingHybrid analytical and numerical solution

Notation

A

Coefficient matrix

a

Radius of circular tire-pavement contact area; constant quantity

B

Column vector of unknown quantities

C

Column vector of known quantities

Cz

Coefficient of consolidation in vertical direction

d

Period of haversine repeated loading without rest period or the duration of loading/unloading phase of the haversine repeated loading with rest period

H

Thickness of clay layer with permeable top and impermeable bottom or half the thickness of a clay layer with permeable top and bottom

k

Number of uniform intervals ∆z in H

L

Loading function (haversine repeated loading with or without rest period)

m

Integer

n*

Number of uniform intervals ∆t within (d)

PTIB

Clay layer with permeable top and impermeable bottom

PTPB

Clay layer with permeable top and bottom

q

Amplitude of haversine repeated loading

R

Rest period

S

Function of time

s

Speed of vehicle for highways or airports

Tv

Dimensionless time factor

t

Actual time

u

Excess pore-water pressure

ue

Imposed excess pore-water pressure

z

Vertical coordinate measured from top surface of the clay layer downward positive

β

Dimensionless coefficient in implicit finite difference equation

σ′

Effective stress

Copyright information

© Springer-Verlag 2011

Authors and Affiliations

  1. 1.Faculty of Civil and Environmental Engineering Chair for Foundation Engineering, Soil & Rock Mechanics, Ruhr-UniversitätBochumGermany