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36 650 strength after 2.1 in. of displacement. This shape is much dif- 600 ferent than the hyperbolic shape of the load-displacement 550 curve for the virgin tests and is likely associated with the differ- 500 T1 Cap 1 Virgin ent deflections required to mobilized adhesive resistance on the 450 T2 Cap 1 Virgin - Excavated soilcrete mass (0.25 in.) relative to that for passive force (2 in.). 400 Cap 1 Jet Grout Load (kips) 350 The load-displacement curve after excavation to a depth of 300 7 ft in front of the jet grout zone is also shown in Figure 3-27. 250 Initially, the stiffness is not much greater than that for the pile 200 group in untreated virgin soil; however, the ultimate resis- 150 tance exceeds 600 kips at a displacement of 3 in. 100 To produce a more readable report, additional plots, simi- 50 lar to those presented for the pile group in virgin clay are not 0 -1 -0.5 0 0.5 1 1.5 2 presented here but are available in Adsero (2008, Appendix 2). Displacement (in) Figure 3-26. Combined load-displacement curves 3.8 Pile Group Load Tests for all tests performed on Pile Cap 1 following jet Involving Soil Mixing grouting. The results from the virgin test also are shown for comparison. Construction Details Plan and profile drawings of the pile group with a soil mix 500 kips equates to an increase in total resistance of about wall on one side of Pile Cap 1 are provided in Figure 3-24. The 2.6 times or 160%. In addition, the initial stiffness of the load- soil mixed wall adjacent to the cap was 10 ft deep, 11 ft wide, displacement curve after jet grouting is considerably higher and extended 4 ft in front of the cap. Because of the small size than the initial stiffness during virgin loading. The pile cap only of the wall, economics did not permit the mobilization of a displaced 0.016 in. at a load of 200 kips. The load-displacement dedicated soil mixing rig to the site. Instead, a procedure curve can be separated into three distinct parts. The initial was applied to produce a volume of soil with a compressive 0.3 in. of the curve are fairly linear. At a displacement of strength and consistency typical of that produced by soil mix- about 0.3 in. the curve shows an abrupt change in slope. A sec- ing. The native soil was first excavated to a depth of 5 ft below ond, relatively linear portion of the curve extends from 0.3 to the top of the cap using a trackhoe. The excavation was then about 1.6 in. of displacement. The third portion of the curve filled to the top of the cap with jet grout spoils from the oppo- following 1.6 in. of displacement is flat with a slight drop off in site side of the cap. Afterward, the remaining intact soil from 900 800 700 600 Load (kips) 500 400 Virgin Virgin - Excavated 300 Jet Grout Jet Grout - Excavated 200 100 0 -0.5 0 0.5 1 1.5 2 2.5 3 3.5 4 Displacement (in) Figure 3-27. Combined load-displacement curves for tests performed on Pile Cap 2 following jet grouting. The results from the virgin test also are shown for comparison.