MECHANICAL EFFECTS OF PORE WATER

EFFETS MECANIQUES DE L'EAU INTERSTITIELLE

(1) TO CARRY OUT LABORATORY AND IN-SITU MEASUREMENTS OF MOISTURE CONTENT AND PORE WATER PRESSURE IN A TWO- DIMENSIONAL MODEL IN ORDER TO CHECK THE EFFECTIVENESS OF THE VERTICAL CAPILLARY SAND SCREEN USED AS A MEANS OF PROTECTING THE SUBGRADE AGAINST THE EDGE EFFECT. (2) THE EFFECT OF THE MOISTURE CONTENT CONDITIONS ON THE MECHANICAL PROPERTIES OF THE SUBGRADE MUST BE KNOWN WHEN COMPARING THE COST OF METHODS OF PROTECTING THE SUBGRADE AGAINST MOISTURE WITH THAT OF STRENGTHENING THE PAVEMENT. MOISTURE CONDITIONS ARE BETTER CHARACTERIZED BY SUCTION THAN BY MOISTURE CONTENT. INDEED THERE EXISTS NO CONSTANT RELATION BETWEEN THOSE TWO VALUES, BUT A CONSTANT RELATION WAS FOUND BETWEEN SUCTION AND DYNAMIC MODULUS OF ELASTICITY. THIS MODULUS WAS DETERMINED ON SILT SAMPLES BY MEANS OF THE RESONANCE METHOD. A STUDY IS CONDUCTED OF THE INFLUENCE OF DIFFERENT FACTORS, ESPECIALLY VIBRATION FREQUENCY, EXTERNAL STRESS, AND THE STRUCTURE OF THE SOIL STUDIED. AN ATTEMPT IS ALSO MADE TO CORRELATE THE DYNAMIC MODULUS OF ELASTICITY WITH OTHER MECHANICAL PROPERTIES (CBR INDEX, STATIC MODULUS OF ELASTICITY).