Solution Manual Vol 7

# 16 effective stress figure q33 figure q34 34 0 20

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Unformatted text preview: because the permeability of the clay is very low. (However, there will be an increase in total stress of 9 kN/m2 due to the increase in unit weight from 16 to 19 kN/m2 between 3 and 6 m depth: this is accompanied by an immediate increase of 9 kN/m2 in pore water pressure.) ; 0v 6 16 3 9:2 3 10:2 154:2 kN=m2 (b) Several years after WT rise: At both depths, pore water pressure is governed by the new WT level, it being assumed that swelling of the clay is complete. At 8 m depth: 0v 94:0 kN=m2 At 12 m depth: 0v 3 16 6 9:2 3 10:2 133:8 kN=m2 (as above) 18 Effective stress 3.6 Total weight: ab 21:0 kN Effective weight: ac 11:2 kN Resultant boundary water force: be 11:9 kN Seepage force: ce 3:4 kN Resultant body force: ae 9:9 kN 73 to horizontal (Refer to Figure Q3.6.) Figure Q3.6 Effective stress 19 3.7 Situation (1): (a) 3 w 2 sat 3 9:8 2 20 69:4 kN=m2 u w h z 9:8f1 3g 39:2 kN=m2 0 u 69:4 39:2 30:2 kN=m2 (b) 2 0:5 4 j i w 0:5 9:8 4:9 kN=m3 # i 0 2 0 j 210:2 4:9 30:2 kN=m2 Situation (2): (a) 1 w 2 sat 1 9:8 2 20 49:8 kN=m2 u w h z 9:8f1 3g 39:2 kN=m2 0 u 49:8 39:2 10:6 kN=m2 (b) 2 0:5 4 j i w 0:5 9:8 4:9 kN=m3 &quot; i 0 2 0 j 210:2 4:9 10:6 kN=m2 3.8 The flow net is drawn in Figure Q2.4. Loss in total head between adjacent equipotentials: h 5:50 5:50 0:50 m Nd 11 Exit hydraulic gradient: ie h 0:50 0:71 s 0:70 20 Effective stress The critical hydraulic gradient is given by Equation 3.9: ic 0 10:2 1:04 9:8 w Therefore, factor of safety against `boiling' (Equation 3.11): F ic 1:04 1:5 ie 0:71 Total head at C: hC nd 2:4 5:50 1:20 m h 11 Nd Elevation head at C: zC 2:50 m Pore water pressure at C: uC 9:81:20 2:50 36 kN=m2 Therefore, effective vertical stress at C: 0C C uC 2:5 20 36 14 kN=m2 For point D: hD 7:3 5:50 3:65 m 11 zD 4:50 m uD 9:83:65 4:50 80 kN=m2 0D D uD 3 9:8 7 20 80 90 kN=m2 3.9 The flow net is drawn in Figure Q2.5. For a soil prism 1.50 3.00 m, adjacent to the piling: hm 2:6 5:00 1:45 m 9 Effective stress 21 Factor of safety against `heaving' (Equation 3.10): F ic 0d 9:7 3:00 2:0 im w hm 9:8 1:45 With a filter: 0d w w hm 9:7 3:00 w ;3 9:8 1:45 ; w 13:5 kN=m2 F Depth of filter 13.5/21 0.65 m (if above water level). Chapter 4 Shear strength 4.1 295 kN=m2 u 120 kN=m2 0 u 295 120 175 kN=m2 f c0 0 tan 0 12 175 tan 30 113 kN=m2 4.2 03 (kN/m2) 100 200 400 800 1 3 (kN/m2) 452 908 1810 3624 01 (kN/m2) 552 1108 2210 4424 The Mohr circles are drawn in Figure Q4.2, together with the failure envelope from which 0 44 . Figure Q4.2 Shear strength 23 4.3 3 (kN/m2) 200 400 600 1 3 (kN/m2) 222 218 220 1 (kN/m2) 422 618 820 The Mohr circles and failure envelope are drawn in Figure Q4.3, from which cu 110 kN/m2 and u 0. Figure Q4.3 4.4 The modified shear strength parameters are 0 tan1 sin 0 tan1 sin 29 26 a0 c0 cos 0 15 cos 29 13 kN=m2 The coordinates of the stress point representing failure conditions in the test are 1 1 1 2 170 85 kN=m2 2 2 1 1 1 3 270 100 185 kN=m2 2 2 The pore water pressure at failure is given by the horizontal distance between this stress point and the modified failure envel...
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## This note was uploaded on 09/21/2009 for the course CVEN 3718 taught by Professor Dobroslavznidarcic during the Spring '08 term at Colorado.

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