Table 1 Essential features of the analysed case histories
Related Figures (24)
Fig. 1. Comparison between results of computations carried out with different codes Figure 1 (Randolph, 1994; Mandolini, 1994b) shows the computed overall pile group stiffness for square groups of piles embedded in an elastic half- space, with L/d=25, E,/G= 1000, v,=0-5, and s/d=2-5 and 5. The group stiffness Ky is defined as the ratio between the total load acting on the pile group and the average settlement of the group. In Fig. 1, the stiffness is normalized as Kp/(sGn°°), where G is the shear modulus of the soil and n the number of piles in the group. The Table 2. Computed and observed average settlement w,, and maximum differential settlement Ona ‘ (a) ‘core’ foundation; (b) ‘dog-leg’ foundation; (c) ‘hammerhead’ foundation; (d) overall. Fig. 3. Case history No. 2: typical soil profile and properties at building site; the subsoil model adopted in the analysis is shown on the right-hand side Fig. 2. Case history No. 2: layout of foundations of the building; pile locations are shown as solid circles, pile caps as full lines and columns as filled rectangles; overall dimensions are 33-6 m X 24-4 m Fig. 5. Case history No. 2: comparison between predicted and observed settlements Fig. 4. Case history No. 2: load—settlement curves of two loading tests on piles Fig. 6. Case history No. 5: schematic of the molasses tank and subsoil model adopted in the analysis Fig. 8. Case history No. 5: comparison between predicted and observed settlements Fig. 7. Case history No. 5: loading test results on single pile Fig. 9. Case history No. 8: layout of the test and subsoil profile It may be seen that the LE analysis allows a rather good prediction of the actual settlement up Considering that the predrilled hole disconnects the pile from the upper gravelly layer, a subsoil model with five elastic layers resting on a rigid base has been adopted in the analysis; it is also shown in Fig. 9. Fig. 10. Case history No. 8: comparison between predicted and observed load—settlement curves; the ELE curve has been obtained using at each load level the secant modulus evaluated at the same level from the load test on a single pile Fig. 11. Case history No. 9: subsoil profile and subsoil model adopted in the analysis; the geometry of the model and the ratio between the moduli of any | layers are the same as assumed by Poulos (1993) Fig. 12. Case history No. 9: comparison between predicted and observed settlements Fig. 13. Case histories Nos. 10, 11 and 12: layout of the foundation Fig. 14. Case histories Nos. 10, 11 and 12: schematic plan and section of the structure Fig. 15. Case histories Nos. 10, 11 and 12: subsoil profile and properties, and subsoil model adopted in the analysi: Fig. 16. Case histories Nos. 10, 11 and 12: load—settlement curves of four load tests on piles (PLC, preloading cell) Fig. 17. Case histories Nos. 10, 11 and 12: loading history and settlement observed during and after ‘onstruction * Pile C underwent a brittle failure at a load of 18 MN. As stated elswhere, the value of Qiim reported in the table is intended only as a geometrical parameter of the hyperbola fitting the initial part of the load—settlement curve. Table 3. Data resulting from the load tests on single piles Table 4. Parameters for the analysis At the site of the bridge over the river Gariglia- no (cases 13 and 17), a set of cross-hole measure- ments of the shear wave velocity were published by Mancuso & Mandolini (1993); they also carried out a number of vibration measurements during the driving of piles, and interpreted them in terms of shear wave velocity. The results they obtained lead to values of the shear modulus Gp equal to 18 MPa in a surface crust, and then increasing with depth from 9 MPa at a depth of 5m to 30 MPa at a depth of 30 m below ground surface. Fig. 18. Case histories Nos. 10, 11 and 12; comparison between predicted and observed settlements for some alignments shown in Fig. 13 and around the perimeter of the raft Fig. 19. Comparison between predicted and observed settlements: (a) average settlement, LE analysis; (b) average settlement, NL analysis; (c) average settlement, ELE analysis; (d) maximum differential settlement, LE and NL analysis; (e) maximum differential settlement, ELE analysis Table 5. Values of the small-strain shear modulus of the pyroclastic soils in the eastern Naples area, as deduced by shear wave velocity measurements and back-figured from load tests on single piles at three building sites Fig. 20. Case history No. 18: soil properties and subsoil model assumed in the analysis Table 6. Comparison between different evaluations of the average settlement of buildings in eastern Naples Area “These analyses refer to a load level lower than that at the end of construction.
