COMPLIANCE INFO_1968-2006 - Laserfiche WebLink

Home Browse Search

112. February, 1968 SA 1 SA 1 weight, depending on their initial composition. Most of the settlement takes differe place,in the first year or two but settlement continues indefinitely at a much fill cat ' decreased rate. partial Because it is considered prudent not to use sanitary fills for the support cause t of structures that are sufficiently important that settlement records would be th kept structural settlement figures If � gores are rare. However, for a public building movem in Georgia, accurate settlement records have been kept on about 40 reference structu points for a 7-yr period. The data for two points approximately 42 ft apart the str in the areas of greatest settlement are shown on Fig. 5. The construction sanitar consisted of a one-story wall-bearing brick building supported by new mat- to pro` like fill approximately 10 ft thick over an old sanitary land fill varying in 1r a thickness up to 25 ft. One end of the structure rests over a relatively rigid y t construction while the other end(in which the settlements shown in Fig. 5 were greater course, observed) rests on the maximum 25-ft thickness of fill. An approximately pared t 6-in. settlement was produced, largely by the 10-ft weight of fill•because structic the structural load is probably equivalent only to that of 1 ft of fill. As can writer': be seen from the graphs, one-half to two-thirds of the settlement took place regardi during the first year. Although the fill' thicknesses are the same at both underta points, neither the settlement amounts nor the rates of settlement are equal. The The result of the differential settlement has been severe cracking on the compac masonry walls. The design of these structures, however, anticipated sub- tires sl stantial settlement. So far, there has been no impairment of the use of the ment is structure, although it has been necessary to readjust the door hinges and to the land where s caulk the cracks. When a three-story structure was placed on new fill up to 10 ft to 15 ft Thos thick overlying a sanitary land fill, 3-in. to 4-in. settlements took place dur- building ing the construction period. Underpinning was required to save the building. Fina: In this case, the new owners were not aware of the nature of the property settlemt ' site they had purchased and their architect had seen no need for making desi ec borings in the nice level site. framing A combination of consolidation and decay caused differential settlement of tolerate : approximately 4 in. in a period of 20 yr in a two-story masonry apartment Stabi. building. supported on 10 ft of sand overlying organic fill 4 ft to 5 ft thick. In 1 this case, there was no measure of the total settlement, although it is esti- cause othe soil mated to be 8 in, to 10 in. e b wast Ravelling failures are characterized by sudden, extremely irregular wastcorres b settlements. At one building site, the ground floor of a three-story school s building was supported directly on the surface of the fill although the building Two fouTwo frame was supported by piles. The floor subsided sporadically, up to 3 in., occur is with such marked irregularities that the floor surface was badly cracked and the cell a transition had to be constructed between the floor and the structurally foundati: supported floors on the stairwells. In several other cases, sudden dropouts it occur, have occurred in the surface of the fills where ravelling of the soil and the the bulg( finer debris into the large voids has creatdd open cavities which left the thin Slidin soil crust above without support. In one such case, a cavity 30 ft deep and sewer w 6 ft in diam suddenly developed in a parking lot immediately beneath an auto- slide tr: ;R l mobile. The automobile was not damaged, but it had to be lifted out by a shear in crane. Steep i. The irregular settlement of fills makes it difficult to design and con- struct underground sewer lines which must flow by gravity. Slopes on such The orrc sewer lines are relatively flat and in cases of which we have record, the are acti7 , r