| 摘要 |
PURPOSE:To make easier the confirmation of pile support stratum without the need to pull up a rod by measuring N values by using a test cone housed in a core tube and also by measuring the time of excavation. CONSTITUTION:Excavation is conducted to a given depth hand feed and the weight of a rod, during which period the excavation time taken is measured for every about 1m. From the excavation time measured, an excavation time Td (the inverse number of speed) is obtained and plotted with depth Z. Since the ground showing a great excavation time Td is proved to be hard, a support layer 1 can be confirmed. Also, a boring rod 2 is connected with the head 5 of a core tube 4 with a metal crown 6 at a screw 3, and also, a penetration bar 7 with a test cone 8 is connected with the lower end of said rod 2. After excavation is conducted to a predetermined depth, the rod 2 is turned in the direction of arrow (b) to separate it from the core tube head 5 and thereby the bring the test cone 8 into contact with the bottom of pit. N values are obtained by penetration test and the support layer 1 is confirmed from a curve A obtained. |
