THE GOW CAISSON

A GOW CAISSON CONSISTS OF A CYLINDRICAL SHAFT, THE BOTTON END OF WHICH RESTS ON A TRUNCATED CONE (KNOWN AS THE BELL) WITH A SHORT CYLINDRICAL BASE. THE BASE OF THE CONE OR BELL RESTS ON A SATISFACTORY BEARING MATERIAL. EXCEPT WHERE THE CAISSON IS UTILIZED TO SUPPORT ECCENTRIC LOADING OR RESIST UPLIFT, NO REINFORCING STEEL IS USED. THE ENTIRE UNIT IS POURED-IN-PLACE CONCRETE WHICH FILLS THE EXCAVATION TO CAISSON CUT-OFF ELEVATION. INSTALLATION INVOLVES NO IMPACT FORCES OR DISPLACEMENT OF SOIL. DETERMINATION OF THE FEASIBILITY OF A CAISSON FOUNDATION REQUIRES ACCURATE SUB-SURFACE DATA FOR STUDY AND DRIVE SAMPLES OF THE SOIL TO BE ENCOUNTERED FOR EXAMINATION. WITHIN THE HEIGHT OF THE BELL THE MATERIAL MUST HAVE THE STRENGTH TO STAND ALONE DURING THE TIME REQUIRED TO COMPLETE THE EXCAVATION AND FILL THE BELL WITH CONCRETE. IN ADDITION THE BELLING MATERIAL MUST NOT LEAK DURING THIS PERIOD. METHODS USED TO COMPLETE CAISSON BELLS IN UNSTABLE BELLING MATERIAL ARE DISCUSSED. INSTALLATION BY HAND METHODS AND BY MACHINE OPERATION ARE DESCRIBED.