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Geotech review midterm Final draft

Valeriya Makarova Geotechnical Engineering Midterm Englisch 126 Karten

Geotech review midterm Final draft

Karten in diesem Stapel (126)

  1. 1How many Phases are in unsaturated soil4, Solid , liquid, air, air-water interface
  2. 2T/F is air-water interface an independent phase?True, because satisfies 2 criteria
  3. 3T/F Saturated soil has 3 phasesFalse. only 2, water and solid
  4. 4what is a state variable and what classifies as suchis a nonmaterial variable required for the characterization of a system, stress condition or deformation. ex: stress, strain, viscosity, hydraulic gradient. lec 1 last page
  5. 5Darcy's law is a type of constitutive relation T/FTrue, Darcy's law is a phenomenologically derived constitutive equation that describes the flow of a fluid through a porous medium
  6. 6State variables can be used to form constitutive relations T/FTrue, constitutive relation is a relation between physical quantities, such as stresses, strain etc which are state variables
  7. 7constitutive relations can be used to define state variables T/FFalse, state variables are components of constitutive relations therefore cannot be defined by it.
  8. 8what does total suction consist ofMetric suction and osmotic suction
  9. 9what is capillarity/ capillary effectcapillarity is surface tension of water which gives curved
    air/water interfaces, also referred to as consequence of surface tension
  10. 10Is capillary effect more important is when water content is relatively lowNo, capillarity does not depend on volume of water
  11. 11Can water tension contribute to the metric potentialYes
  12. 12What does osmotic suction refer tosolutions of different concentrations are separated by a semi-permeable membrane
  13. 13what is SWCCSoil-water characteristic curve
  14. 14which relationship does SWCC refer toWater content and metric suction
  15. 15What can SWCC be used to describethe Ability of soil to retain water at different metric suction
  16. 16Can SWCC be used to predict the material properties of unsaturated soilYes
  17. 17SWCC can only be used to describe the water retention capacity of unsaturated soil T/FFalse, SWCC has many applications
  18. 18T/F Smaller pore size can result in lower water retention capacityFalse, smaller pores such as in clay soils will result in increased water retention capacity
  19. 19T/F SWCC is higher from sand soil than that obtained in clay soilFalse
  20. 20air entry value is higher in the clay soil compared to that from sand soil T/FTrue
  21. 21Absorption value is more important when the water content is relatively high T/FFalse, Absorption value does not depend on the water content of the soil
  22. 22What is AEVAEV is Air Entry Value, and defined as the value of suction where the water content begins to drop quickly during the drying process. In which the air starts entering the largest pores
  23. 23if the metric suction is not equal to zero, the soil may be still in fully saturated state T/FTrue
  24. 24if the metric suction is greater than the the entry value, degree of saturation may not equal to 1 T/FFalse
  25. 25When the air starts entering the soil, the air will enter the smallest soil pores first T/FFalse, will enter larger pores first
  26. 26Coarse-grained soil has relatively large air entry value compared to fine-grained soil T/FFalse
  27. 27what is Contractile skinalso called air-water interference, an independent phase in soil (fourth phase) most distinctive property is its ability to exert tensile pull
  28. 28Contractile skin can be considered an Independent phase T/FTrue, contractile skin is considered an independent phase
  29. 29Contractile skin can exert tensile pull to pore water T/FTrue
  30. 30Contractile skin can affect the magnitude of metric suction T/FTrue
  31. 31Contractile skin can be considered to be part of the solid phase T/FFalse, Contractile skin is an independent phase but can be considered as part of the water phase
  32. 32Surface tension is able to maintain the stability of air-water interference T/FTrue
  33. 33Surface tension is measured as force per unit length and thus is a type of state variable T/FFalse
  34. 34Warmer temperature can decrease the surface tension T/FTrue
  35. 35Solute in the water may increase or decrease the water tension T/FTrue
  36. 36Contact angle is material property and thus is constant for a particular type of liquid T/FFalse, contact angle depends on liquid/solid and liquid/gas interference and those are not constant.
  37. 37Surface tension is considered wettable if the angle is less than 90% T/FTrue
  38. 38For a particular type of solid surface , its wettability is variable T/FTrue
  39. 39Contact angle can be used to evaluate the metric suction T/FTrue
  40. 40What is elevation headelevation of the fluid above the arbitrarily designated zero point
  41. 41For a particular spatial position, its elevation head is variable T/FTrue
  42. 42Zero elevation head always refers to the point on the ground surface T/FFalse, point zero can be at any chosen point
  43. 43Hydraulic gradient changes may affect the magnitude of elevation head T/FFalse, hydraulic head is not affected by the changes in the hydraulic gradient
  44. 44Elevation head is always negative when the point of interest is located in unsaturated soil T/FFalse
  45. 45What is Pressure Headmeasure of the pore pressure of the water in the soil
  46. 46Soil is in the unsaturated state when pressure is negative T/FFalse, if the water pressure is negative it simply indicates the suction potential in the soil and not always unsaturated soil
  47. 47Pressure is negative when the soil is in unsaturated state T/FTrue
  48. 48Pressure head dominates the water flow in unsaturated soil T/FFalse
  49. 49Pressure head is always positive when the point of interest is located in fully saturated soil T/FFalse, pressure head being positive indicates that the water is being pushed out but this does not always mean the soil is fully is saturated
  50. 50What is the quantity that will be fixed if the position if the datum is changedHead loss
  51. 51What is Hysteresisdefined as the difference in the relationship between the water content of the soil and the corresponding water potential obtained under wetting and drying process
  52. 52If the water content is the same in the same soil sample, Matric suction from drying path is similar to that from a wetting path T/FFalse, if the water content is the same this will result in different Matric suction between wetted and drying path
  53. 53If metric suction is the same in the same soil sample, water content in the drying path is relatively high compared to the wetted path T/FTrue
  54. 54When the soil type is specified, its SWCC is a unique relationship between water content and Matric suction T/FFalse
  55. 55Water retention capacity in the wetting path is stronger than that from the drying path T/FFalse
  56. 56Geometric non uniformity of soil pore causes different Matric suction T/FFalse
  57. 57Water content in the drying path is always higher than that in the wetting path T/FFalse, not always
  58. 58Contact angle effect causes different water content corresponding to the same Matric suction T/FFalse
  59. 59Soil expansion may decrease the water retention ability T/FTrue
  60. 60Soil compaction refers to the densification of soil by removal or pre water, which requires mechanical energy T/FFalse
  61. 61Soil compaction is non-suitable for saturated soils T/FTrue
  62. 62Soil Compaction aims to increase the strength of the soil and decrease the settlement of structures T/FTrue
  63. 63Soil compaction may decrease the dry density of unsaturated soil when water content is on the wet side of the compaction curve T/FTrue
  64. 64On the dry side side, a flocculated soil structure can be formed and result in large pore size T/FTrue, this is due to the water content being low and repulsive force between solid particles is weak. therefore, the soil specimens have flocculated structure and result in larger clod sizes
  65. 65Compared with the soil on the wet side, larger hydraulic conductivity can be obtained on the dry side T/FTrue, water content is relatively low, and repulsive force between solid particles is weak. the structure produces allows for the permeability to be on the higher side
  66. 66Compared with the soil on dry side, weaker water retention capacity can be obtained on the wet side T/FFalse, The water retention capacity is relatively large
  67. 67what structure does the soil have on the wet side of the compaction curveDispersed, which also results in smaller clod sizes
  68. 68Without the existence of pure water, osmosis cannot take place between different solutions T/FFalse, osmosis is defined by the delusion of water through membrane. does not necessarily need pure water always can occur in other solutions
  69. 69What is osmotic PotentialOsmotic potential is a measure of tendency of a solution to withdraw water from pure water by osmosis across semi permanent membrane
  70. 70Matric suction can be used to describe the ability of soil to hold the water T/FTrue
  71. 71Matric suction can be determined directly by the water vapour pressure above the air-water interference T/FFalse, Total suction can be determined that way not matric
  72. 72Total suction can be determined directly by the water pressure in unsaturated soils T/FFalse, this method is used for osmotic suction
  73. 73If the measurement is related to liquid water in soil, the measurement suction is matric suction T/FTrue
  74. 74If the measurement is related to water vapour, the measured suction refers to the total suction T/FTrue
  75. 75relative humidity increases as the total suction increases T/FFalse
  76. 76Total suction is non negative T/FTrue
  77. 77What features does filter paper technique consist of- indirect measurement of soil suction
    can also be used to measure total and matric soil suction
  78. 78Calibration curve is a type of water retention curve T/FTrue, acts similar to SWCC
  79. 79Calibration curve represents the water retention capacity of the measured soil T/FFalse
  80. 80Calibration Curve refers to the relationship between suction and water content T/FTrue
  81. 81Calibration curve is similar to SWCC in terms of characterization of water retention T/FTrue
  82. 82A filter paper was inserted into a soil sample. then through the measured water content and calibration curve of the filter paper, the suction in the filter paper is determined and equal to 200kPa. based on the given information, please identify the correct type of suction presentMatric suction is 200 kPa
  83. 83What is the "break point along the calibration curve of filter paper is induced byinduced by the different mechanisms responsible for the water retention capacity or dominant mechanism switched from absorption to capillary effect as water content increases
  84. 84What is required to predict the hydraulic conductivity in soilSWCC and saturated hydraulic conductivity
  85. 85what is HAE ceramicshigh air entry, a type of ceramic stone which acts as an important aspect of measuring and controlling soil suction in the lab and the field
  86. 86is the usage of the HAE ceramics in measurement of soil function to prevent the air entering system?Yes
  87. 87Does HAE ceramic increase the water absorption capacity or increase the water retention in the soil?No
  88. 88smaller air entry value of ceramic can increase the measurement range of soil suction T/FFalse, the smaller pore size only prevent the air from entering the measuring system
  89. 89Generation of air bubbles can increase the water pressure in the measuring system T/FTrue
  90. 90The measurement range of the ceramic is dependant only on AEV T/FFalse, it is needed but it isn't the only thing HAE ceramic measurement range depends on
  91. 91Larger pore size of ceramic is able to increase the measurement range of soil suction T/FFalse
  92. 92what is the AEV measuring capacity of HAE ceramic for both sintered and cells membranes1500kPa for sintered and 10,000kPa for cellulose
  93. 93what is axis translation techniquerefers to the method of elevating air pressure while maintaining the water pressure at a measurable reference value, typically atmospheric
  94. 94axis translation technique is an indirect measurement method of matric suctions T/FFalse
  95. 95Axis translation Technique can be used to measure total suction and matric suction in soil T/FFalse, that's the filter paper method
  96. 96The use of axis translation technique won't change in matric suction and water content in soil T/FTrue
  97. 97The usage of axis translation technique won't change the measurement range in soil suction T/FFalse
  98. 98What devices can be used to measure suction in the fieldTensiometer
  99. 99What is a tensiometera sealed water filled tube with HAE ceramic tip at one end and a device for measuring negative water pressure on the other, used for measuring soil suction
  100. 100Can the tensiometer be used to measure a complete spcc though a single soil sample?Yes
  101. 101pore air pressure and pore water pressure increases simultaneously during the measurement though a pressure plateFalse
  102. 102During the measurement, water pressure in measuring system is same to the applied air pressure inside the metric plate T/FFalse, the water pressure in the system is equal to 0
  103. 103A series of soil specimens with different water content is required to determine the complete swcc through a pressure plate T/FFalse, SWCC can be obtained through the continuous measurement of matric suction vs water content on the same specimen
  104. 104Matric suction in soil specimens is same to the applied air pressure inside the pressure plate T/FTrue
  105. 105A pressure plate is used to measure soil suction and applied air pressure is set to 250kPa. Based on the given information can the matric suction be detained?yes
  106. 106K increases as the matric suction increases in the soil T/FFalse, only factors affecting hydraulic conductivity are soil skeleton, fluid properties and degree of saturation
  107. 107When water content is fixed, k in the drying path is smaller than the K in the wetting path T/FTrue,
  108. 108K of the fine grained soils is always greater than K of unsaturated soil T/FFalse, K value does not always depend just on the grain size of the soil other factors might affect the hydraulic conductivity outside of the structure and grain size
  109. 109Soil compaction cannot affect the magnitude of K in unsaturated soils T/FFalse, with the compaction the air voids in the unsaturated soil decrease which will lead to the change in the soil skeleton and decrease or decrease the hydraulic conductivity
  110. 110For saturated soils, the soil skeleton is the dominant factor affecting k T/FTrue
  111. 111For unsaturated soils, water content plays the dominant role in the magnitude of k T/FTrue
  112. 112Compared with the soil skeleton and water content, the water content, the fluid properties play relatively weak role in magnitude of k T/FTrue
  113. 113the factors affecting saturated K are completely the same to those affecting unsaturated kfalse
  114. 114Seepage velocity refers to the water flow velocity through pores pace occupied by water T/FTrue
  115. 115Seepage velocity is always greater than discharge velocity T/FTrue
  116. 116Seepage velocity and discharge velocity can be related to each other through porosity in unsaturated soil T/FFalse
  117. 117Discharge velocity refers to the average water flow velocity in soil T/FTrue
  118. 118Darcys law aims to directly calculate the seepage velocity in saturated soil T/FFalse, Darcys law aims to show that discharge is proportional to the hydraulic gradient and the aquifer material. aka finding discharge velocity
  119. 119When the hydraulic conductivity is expressed as a function of water content, the modified Darcys law can be used to evaluate the discharged velocity on unsaturated soil T/FTrue
  120. 120The negative sign in Darcys law indicates the water flow in the direction of decreasing total head T/FTrue
  121. 121Headloss is a non positive quantity T/FTrue
  122. 122For a given soil sample, its metric suction is 200 kPa and the air entry value is 150 kPa . Based on the given information is the soil in the saturated state?no, the soil is in unsaturated state, if the soil sample presents a higher metric suction compared to aev we can assume that the soils tends to absorb water at a larger rate than air, therefore we can assume unsaturated state
  123. 123based on the image above, which curve has a larger AEV valueCurve A, we can also assume that the curve A is a more fine grained soil due to larger AEV and larger water retention. and soil in curve A has larger residual water contentbased on the image above, which curve has a larger AEV value
  124. 124For an unsaturated soil sample, total weight is 0.05kN, dry weight 0.04kN and specific gravity of 2.5. what is the volumetric water content of the soil.Volumetric water content is equal to 25%
    Ans. (TW-DW)/DW= water content
    (0.05-0.04)/0.04=0.25 or 25%
  125. 125based on the figure shown is the elevation head along water table is zero?No, datum is shown to be at the very bottom of the soil therefore the elevation head is 6.5m at water tablebased on the figure shown is the elevation head along water table is zero?
  126. 126Based on the above figure is the elevation head positive in the unsaturated soil above the water table?Yes, the elevation head at the ground level/ unsaturated soil is positive due to the datum of the elevation head being at the bottomBased on the above figure is the elevation head positive in the unsaturated soil above the water table?

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Midterm Geotechnical Engineering Karteikarten am Geotech review midterm Final draft, erstellt von Valeriya Makarova am 23/02/2023.
Erstellt von
Valeriya Makarova
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