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Unformatted text preview: controlled - insert slug of fluid, measure pressure. o Self-boring PMT has cutting head with jets to make its own hole. Overjetting and small roots and gravel create big problems but the data is potentially very good. o Push-in PMTs (Pencel) similar in size to CPT. These eliminate hole disturbance but cause penetration disturbance - lose early part of PV curve. Remedy with unload-reload loop. o Determine shear modulus from straight-line portion of PV curve. Analyze radial expansion of probe (assumed equal in all directions). Correlate E vs. G using theory of elasticity and assumed fl. o Estimate lateral stress based on pressure, Po, the pressure at start of straight-line portion of curve. o Estimate shear strength based on failure at limit pressure, PI, where pv curve flattens out (assuming failure is achieved)....
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- Fall '08