Solution Manual Vol 7

16 effective stress figure q33 figure q34 34 0 20

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

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 " 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...
View Full Document

This note was uploaded on 09/21/2009 for the course CVEN 3718 taught by Professor Dobroslavznidarcic during the Spring '08 term at Colorado.

Ask a homework question - tutors are online