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I <br /> 1 <br /> EG <br />' Pore Pressure issipa ion less <br /> (PPDT) <br /> Pore Pressure Dissipation Tests (PPDT's) conducted at various tntervals <br />' measured hydrostatic water pressures and determined the approximate depth of <br /> the ground water table A PPDT is conducted when the cone is halted at specific <br /> intervals determined by the field representative The variation of the penetration <br />' pore pressure (u) with time is measured behind the tip of the cone and recorded <br /> by a computer system <br /> Pore pressure dissipation data can be interpreted to provide estimates of <br />' O Equilibrium piezometric pressure <br /> O Phreatic Surface <br /> o In situ horizontal coefficient of consolidation (ch) <br /> 1 O In situ horizontal coefficient of permability(kh) <br /> in order to correctly interpret the equilibrium piezometric pressure and/or fhe <br />' phreatic surface, the pore pressure must be monitored until such time as there is <br /> no vanation in pore pressure with time, Figure PPDT This time is commonly <br /> • referred to as ttoo, the point at which 100% of the excess pore pressure has <br />' dissipated <br />' A complete reference <br /> on pore pressure <br /> dissipation tests is e b 'J <br />' presented by <br /> (fC.+RM'1 m ar>sc ar vare rL a aY <br /> Robertson et al 1991 %L 1 N° ' <br /> A summary of the pore <br />' pressure dissipation v — ►`rTanlg , w L .�P . e <br /> tests is summarized in <br /> Table 1 Pore pressure <br />' dissipation data is Pore pressure(u) <br /> presented in graphical qu-maxed mire <br /> form in Appendix rt,-- 1)aPtl Cf 0179 r <br /> PPDT 'k,.r� -H"dOt W ` <br /> M�'dler Tdl�E--a.,.d.lUr <br /> where HwaLer=Ue(depth units) <br />' usUR-A Convemor h8c101. 1p.<A=U/L4(r =151 (Oct (wat4r, <br /> l tsf-O'tz bar-1j 9P81 <br /> 1 -3.18 toot <br />' Figure PPDT <br />