Volume 39, Issue 5 (September 2011)
Development and Calibration of an Electronic Miniature Cone Penetrometer for Design of Small Piles in Silty Clays
For the design of shallowly embedded small size pile under lateral load, a new kind of electronic miniature cone penetrometer is developed. And a novel mini calibration chamber is also designed to form homogeneous soil specimens for miniature cone penetration test (MCPT) in laboratory. A series of MCPTs and pile loading tests in silty clay are carried out. For silty clay, penetration curve has no correlation with cone angles within the tested range of 19° to 32°. The initial segment of penetration curve is linear for silty clay. However, the cone tip resistance tends to be stable when the cone is penetrated to a certain depth. It is implied that the critical depth effect occurs for MCPT of silty clay. For silty clay, the critical depth effect is caused by different soil failure mechanisms under different confining pressures. The lateral bearing capacity and stiffness of small size pile are all directly related to the ultimate cone tip resistance of soil. It is concluded that the miniature cone penetrometer is an effective apparatus for the design of small size shallowly embedded pile.