Childrens Heart Foundation

THE WRITER APPRECIATES GUPTA'S CLARIFICATION OF THE PILE RESISTANCE ATTRIBUTED TO THE CHANGE OF POREWATER PRESSURE AND EFFECTIVE SOIL STRESS. DURING PILE DRIVING THE POREWATER PRESSURES IN THE SAND, IMMEDIATELY SURROUNDING THE PILE SURFACE, DROP DUE TO TEMPORARY EXTERNAL COMPRESSION, THEREBY INCREASING THE EFFECTIVE STRESS AND SHEARING RESISTANCE. MANY PRACTICING ENGINEERS HAVE HAD EXPERIENCE WITH SOILS ADHERING TO THE PILE SURFACE AFTER IT HAS BEEN RETRACTED FROM THE GROUND. IN THE EVALUATION OF THE OVER-PILE RESISTANCE SUCH A STIFF SOIL RING SHOULD BE CONSIDERED AS AN INTEGRAL PART OF THE PILE AND THE SATURATED SAND BEYOND THIS RING CONSIDERED AS ACTING AS A CONTAINER OF HYDRAULIC JACK IF THE EQUALIZATION OF POREWATER PRESSURE IS SUFFICIENTLY SLOW TO PERMIT THE BUILD-UP OF RESISTANCE AT THE PILE TIP. GUPTA'S DISCUSSION ON REDRIVING RESISTANCE OF PILES IN LOOSE SAND ARE VALID. AS THE EQUALIZATION OF POREWATER PRESSURE IS RATHER FAST IN LOOSE SAND, THE DRIVING PATTERN IN LOOSE SAND IS VERY SIMILAR TO THAT SHOWN IN FIG. 3. THE PILE RESISTANCE AT THE VERY BEGINNING OF REDRIVING COULD BE A RELIABLE INDICATOR IN REPRESENTING THE STATIC CAPACITY OF A PILE. /AUTHOR/

ITEMIZED REPILES ARE MADE TO QUESTIONS AND COMMENTS OF DISCUSSERS. THE MAJOR TOPICS COVERED ARE THE EMBANKMENT SECTION, UNDERWATER FOUNDATION FILL, EFFECTS OF AN EARTHQUAKE ON THE DAM, AND UNDERSEEPAGE.