Question

please show step by step (also show how to find the vertical stress increase)

18 A new petroleum storage tank is proposed at an oil refinery to be supported by a 20-meter diameter slab foundation at the ground surface. The structure will produce a uniform load of 110 kN/m2 on the entire slab foundation. A subsurface investigation has revealed the shown soil profile. A series of laboratory tests on representative samples obtained from the clay stratum has resulted in the following clay soil is normally consolidated clay soil in-situ void ratio is 0.75 average compression index is 0.30 average coefficient of consolidation is 1.2 x 102 m2/day average coefficient of secondary compression is 8.5 x 10 (a) Estimate the ultimate settlement due to primary consolidation of the clay layer. (b) If the primary consolidation was completed two years after the completion of the structure, what would be the estimated settlement due to secondary compression 30 years after the completion of the structure? redict how long it may take for 90 percent of the settlement, due to primary consolidation, to take place after the construction. (c) P Ground surface 1.8 m Sity sand 18.2 kN/m Water table 1.2 m 19.0 KN/m3 Silty sand 7.4 m y 16.8 kN/m3 Clay Dense sandy gravel

Answer 1

on hal effe chve verhical stress at the. center where Pore water pressure at the center f clay 1 ajer water Uni)-weigh- tl KN/ m,3 9.81 titat waer table sbeve the center CemreY clay lag aA. er, 3チ+1·2. kn/mP . 248-069 ' t 2 8.069

Verical stress mcreas e af the Centes clay Laer There are various methois uhich can be loaded circular aγea. shere, 4o%- Vertic ol cres in cre e 2010 m ズ z Depth al-- hich shress usto be hund. # 6-7 h, . From the above equahim we zek method, uses df. anッ Swihable'm

Find ef} edrive stress al- rhe cente γ 9.6S+1.03 Now a) Primary Csn-so bi d ation seltlement is awem by o: iR. ew he re M Duickness o dlay lagey Ty C Compression ndex o.3o 160.68 69. 6s 1 o.ts Ans.

Se comdmession sab lermenk is given , ts ne ne = 8.5x10-3 HtsThickness cla Layer afher prima) CensplidA Ho S = 6.939s m. time aJ-which secondary con soli d akim ù requi red.시rer primary consoli dahon t s 30-2 28 JTS e Time 2- JTs → |ss = 6-76 cm.

pr imAry con so lid ah on Let it be ta。 ere U 90% . Time tacar ( Tv): レFA-o-9331 log 1100-U 1.7 81 0.933 (loo-0 Thick ness f drai nage patt d double drainage condi Hon 2 single arainage Condirton I n twis case porous sama both bop anå. bortom f the cay ayer. He n co double drain ate CondinmeM15k is provided at- 2- 2

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