THE USE OF LIGHTWEIGHT PERCUSSIVE BORING RIG IN ROAD CONSTRUCTION

THE AUTHOR BRIEFLY DESCRIBES THE PERCUSSIVE BORING RIG DEVELOPED AT THE CENTRE DE RECHERCHES ROUTIERES AND ITS USE, AND OUTLINES THE MAIN METHODS OF INTERPRETING THE TESTS CARRIED OUT WITH THE ABOVE RIG. DETAILS ARE GIVEN OF TEST RESULTS COMPARING THE DRIVING DEPTH ACHIEVED BY BLOWS TO THE CALIFORNIA BEARING RATIO OF VARIOUS SOILS COMPACTED IN THE LABORATORY OR IN-SITU. STATISTICAL ANALYSES SHOW THAT A GOOD CORRELATION EXISTS FOR MOST TYPES OF SOIL, WHICH ENABLES THE CBR INDEX TO BE ESTIMATED FROM THE DRIVING DEPTH, THE ERROR NOT EXCEEDING 30 TO 40% IN RELATIVE VALUE. A CORRELATION OF THIS TYPE EXISTS FOR ALL FINE SOILS FROM CLAY TO FINE SANDY SOIL.