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SUMMARY:The strength and stiffness of jacked piles in sand - Andrew Deeks\
 , CUED
DTSTART:20080620T153000Z
DTEND:20080620T163000Z
UID:TALK11456@talks.cam.ac.uk
CONTACT:Zelda Stuck
DESCRIPTION:The method by which a pile is installed influences the 'perfor
 mance' of the resulting foundation because it affects the strength and sti
 ffness. To develop simple models that can predict the performance of jacke
 d piles a combination of physical testing and theoretical modelling were u
 sed.\n\nThis presentation will cover three key points:\n\n-Methods to pred
 ict the axial strength and stiffness of a jacked pile are outlined.\n\n-A 
 new pile jacking technique in which torque and axial force are applied sim
 ultaneously to install tubular displacement piles by rotating them into th
 e ground is described. Methods to predict the axial and torsional installa
 tion loads based on failure envelopes and plasticity concepts are presente
 d.\n\n-Fascinating observations emerge in relation to the stress field aro
 und a displacement pile when large rotations were applied. The unit shaft 
 resistance was consistently observed to increase during continuous rotatio
 n of the pile in the centrifuge model tests. Mechanisms are proposed that 
 link this increase in strength to the observation of increasing pile capac
 ity with time ('set-up') in the field.\n
LOCATION:Engineering Department - **LR4**
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