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CEG3011 exam 2 key

CEG3011 exam 2 key - CEG 3011 Soil Mechanics Exam 2 Spring...

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Unformatted text preview: CEG 3011 Soil Mechanics Exam 2 Spring 2010 ./ , . 7 Score ’ Problem 1 A. For a constant head permeability test on a fine sand, the following values are given: 0 Length of specimen = 10 in. Diameter of specimen = 2.5 in. O 0 Head difference = 18 in. 0 Water collected in a period of 2 min = 0.031 in.a Determine: a. The Hydraulic conductivity, k, of the soil (in in./min) b. Discharge velocity (in in./rnin) c. Seepage velocity (in in. /min) The void ratio of the soil specimen is 0.46. a) K:%L 0333/0 xi: /.75,>< /0“‘%‘w 5:“. IRE; { :7gQQIIZGX/5XZ / :4. I ,M . 359W: 9/ ~/00W¥925))a5)bw MMXXOB 0905/0 #49 (1)016: 73/73 Vflié’zéhgb 0’73 .5 M f/ Q§$:50/f5_/3£ -,-, 9%? 3% w >70 5;: 0 6:132:36?ng $4.413» In a falling head permeability test the initial head of 1.00 m dropped to 0.35 m in 3 hours, the diameter of the standpipe being 5 mm The soil specimen was 200 mm long by 100 in diameter. Calculate the hydraulic conductivity of the soil. ”(-2 80%fié; 9L0} Io (2:13;?) \ ‘0 Problem 2 A soil lab informed you the soil sample you send from the field has a maximum dry unit weight of 115 PCP and an optimum water content of 14% when the soil was compacted using standard proctor. In the field, where you are currently working, the specification calls for a minimum relative compaction of 95% of the maximum dry unit weight obtained from the standard Proctor. The specification also calls for the water content during compaction to be wet of optimum. You were the QA/QC officer on site. You dig a hole that is 0.032 ft3 in the compacted soil layer and extract the soil from the hole. The soil from the hole weighs 4.15 lbswet and 3.65 lbs dry. (1 0 Draw a typical compaction curve that can be obtained from the standard Proctor test. H Show the maximum dry unit weight and the optimum water content What is the dry unit weight in the field What is the water content in the field What is the percent compaction in the field Were the compaction criteria met in the field (How) ,L‘fifi O #51900 , :s ,, HQ‘HG a. /0g. ‘ r . ,. a; , ‘25— - wms— :L ,3 “T?“e ' . {ff/oui“; t“?§/>-//%w N967 jg l {/W [/9' :2 *1/04 saw-J has ta OMI'M V0.9 LU rs - ‘9 9‘59) 0V écaymgy‘ ff, Problem 3 The following figure shows the THREE SOILS in a tube that is 100 mm X 100 mm in cross— section. Water is supplied to maintain a constant head difference of 300 mm across the samples. The rate of water supply is 500 cm3/hr and the hydraulic conductivity of the soils in the direction of flow through are as follows: Soil k (cm/sec) A 10-2 B 5 X 10-3 ,0 a. Determine hA. G b. Determine hB. (0 0. Determine hydraulic conductivity of soil C. 3"517'21Water SLtzpply .V - n _ _ u. .. _. -w. W. .. m .. .N _.. ‘ i (. ( ms! nu lu u! :505‘2 mm ‘Illcunu. {w 150 mm +‘< 1 501mm «>3«— 150 mm of Q.» ’@:)D(L#§, A: /Qr</j“lu0%%”/Omfi”ah/_AQ‘ 53W) (9]: £3353 .3» @‘[email protected] Qua/,4": if arm/we) égnfw ‘ v ”98674::3 €9279/3éjx , 'V b) QKHLA 3::(?Z%;:}76 Q .-. 0.7-3 a; 5M 3’3wa WLLIELAQ fflééMBJ‘Q twinning; i a, Ala/4L: mgr-he Ma: 25 74>, 332$ e??? M333 :iijaierfl Was-as.- mv 5 r!) w . lfw 0/3e>_/M§owo, W09 ”4671’ gglfiaxxs 5:0er .L 4-2: if‘g ,.. ,2“ 74,5; "7?” ’ $9 1,, ,3 Q :1“ng , W ~ 0” an M {3'15 (Rm/ad A oJagnggJ,S’;-Zév‘7m</ . 0.6%: 44(W mo “'f“ was [~42 :2; 5291K Q ’AWGAGJflrfp Problem 4 Consider seepage occurring around the levee shown below. For the soil: k = 10-6 m/second. Given the flownet, and the dimensions provided, compute the following: - Number of flow Channels? — Numbers of drops 3 _ — The volumetric flow rate beneath the structure per unit width in the out-of plane 6 direction; - The porewater pressure at point A. /0 \ . “ “93 H vé" Q) Q=KW§hL- ° ie’ {fig 99/0 XTISXL ;' $3 H+A= 25~Zrizxaé 2;: 754-815“ = $405929: ' as: hLPP : ’L’LT'“ Hz. :: 20.45~(-=—/o> :: /Ou égwig' - r» .1” ':.fi =1" - 52'” $343453; é!“ \{xi egigwul§fi4§ W24, r m iii/)3 £9? E: l V, ”W" 49:9 I 4' I: .2 7);? ' iffifis Liliana, jWnQ’»QW 1, Problem 5 A uniformly distributed pressure of 200 kPa1s applied on 10 m strip footing on the soil profile shown below. a) Find Total vertical stress, porewater pressure, and effective stress at Point A before the footing was constructed. b) Find the increase in vertical stress at point A, after the footing was placed (Due to footing). Show work in details Clay Ilnpermeable Saturated unit weight = 18 kN/m3 Bedrock Sand Saturated unit weight = 20.4 kN/m3 Dry unit weight = 18.5 kN/m3 G~> 01:: 531-12141- I.S><3491¢% «113.1133 :8.§: 18515;” 111%,723. # U11 : ecsog @1211 xii-3373641 AZ 1,.» Z” {721 :1 :3! 7331011 1%: 1, i9 12:13-10 0211;931:159, ‘3 . 0%,: (agwa 1/" ‘ I (4 $15”: 13%2, 1/15/1415. wéfi ”/4 Vii/134?“ (771/2113 1/%21é5711:a 191111213151 2:13 égMi/fi ( Maj/”g 3/0”“ 87%) $605 [bf/fl?” ...
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