Table of Contents
Advertisement
30
APPENDIX D. TEMPERATURE EFFECT ON EARTH PRESSURE AND
CONCRETE STRESS CELLS
The following theoretical treatment is by no means rigorous — there are some questionable
assumptions and approximations — but it should give some idea of the magnitude of the thermal
effect to be expected on hydraulic earth pressure cells, buried in soil, or installed at the contact
between soil and structure, and on concrete stress cells embedded in concrete.
Figure 19 - Radius (R) and Thickness (D)
D.1 Formulas
Consider a circular cell of radius (R) containing a liquid film of a thickness (D), coefficient of
thermal expansion Kppm/°C, and bulk modulus (G).
For a temperature rise of 1 °C the expansion (Y
) of the liquid film is given by the equation:
T
Y
= KD
T
Equation 7 - Expansion of Liquid for a Temperature Rise of 1° C
Expansion of the liquid is resisted by the confinement of the surrounding medium (soil or
concrete) and this causes a pressure rise (P) in the liquid, as well as a compression of the liquid
(Y
) given by the equation:
c
Y
= PD/G
c
Equation 8 - Compression of Liquid
The net expansion (Y) of the cell is equal to:
Y = D (K- P/G)
Equation 9 - Expansion of Liquid
Advertisement
Table of Contents
