3003 W CASINO RD BLDG 40-56 Geotech Report 2018-01-02 MF Import

If caissons are constructed adjacent to an existing caisson, the latter will experience settlement induced from the stress overlap. The settlements are estimated to be 1/8 or less if the I8-inch wall-to-wall spacing is maintained. 5.2.4 Downdrag Downdrag loads may be experienced by caissons located within the organic -rich zone identified on Plate 9. The downdras loads would result from the long term decomposition and compression of organic materials accompanied by settlement of the overlying fill soils. Downdmg loads will be highest at locations where the highly organic pockets an located deepest within the fill layer. We estimate that downdrag beds of up to 350 kips may occur for 3 feet diameter sharp and 500 kips for 4 diameter shafts. This lad will be in addition to that imposed by the proposed structure itself. Since the distribution of these highly organic pockets within the fill layer appears to be quite variable, we recommend that all caissons within the organic -rich sotto be designed for the above -mentioned downdrag load magnitudes. We know of no reasonable means of reducing the dowadrag effect on cast -in -place caissons. 5.2.5 Cnnff�gn The proposed caisson foundation may have caisson lengths vary between 20 feet to 140 feet. Obstructions are expected in the fill soils. The obstruction materials may include old concrete pieces, boulders, tree trunks and other construction debris. Previous caisson installation records indicate caving problems in the random fill. Temporary steel ,sing was used in the previous construction and should be anticipated for the current expansion. Note that the City of Everett requires that the length to diameter ratio be less than 30 for caissons poured without permanent casings. For deep caissons, the hole may be advanced with a combination of cuing and drill mud. In any cue, concrete should be tremied in place. If cuing is to be retrieved, the top of the concrete a•005.00695.016\ssoa0?W.aW 00695.509.016 11