Relationship of friction and shear displacement along the depth of shaft-grouted mini-piles and a case study

Abstract

In Hong Kong, piled foundations using shaft-grouted frictional piles have become more commonly adopted, in particular, for areas where bedrock can only be found at a very deep level. In the design aspect, there are various theoretical methods (e.g. α method, rβ method, Nottingham and Schmertmann cone penetration test method and N-value method) available to compute the design shaft friction; in situ measurements of the values of the shaft friction have also been carried out by numerous researchers to validate the design values. However, there is limited information on the correlation between the mobilised shaft friction and the shear displacement at the pile–soil interface. This paper presents the use of shaft-grouted frictional mini-piles founding on soil in a project of Architectural Services Department of the HKSAR Government. The load-tested results of two instrumented piles from that project followed by a discussion on the findings regarding the relationship between the mobilised shaft friction and th...