Deck 11: Soils and Excavations

Question 1

Grading at a site refers to

A)evaluating the groundwater conditions at a site.
B)evaluating the existing subsurface conditions of a site.
C)compacting the soil to required density.
D)all of the above.
E)none of the above.

Answer 1

E

Question 2

In the commonly used soil classification system, sand and silt are classified as

A)coarse- grained soils.
B)inorganic soils.
C)fine- grained soils.
D)organic soils.
E)none of the above.

Answer 2

E

Question 3

Which of the following statements is correct?

A)Gravel particles have a platelike shape.
B)Clay particles have a platelike shape.
C)Sand particles have a platelike shape.
D)Silt particles have a platelike shape.

Answer 3

B

Question 4

During soil testing, soil samples are obtained from

A)several locations on the site and from several depths below ground.
B)one central location on the site but from different depths below ground.
C)several locations on the site but from the same depth below ground.
D)none of the above.

Question 5

The bearing capacity of a soil refers to

A)whether the soil is native to the site.
B)the density of soil.
C)the modulus of elasticity of soil.
D)the compressive strength of soil.
E)none of the above.

Question 6

Soil and rock consist essentially of the same matter.

Question 7

The building codes do not mandate geotechnical investigations for all building construction sites.

Question 8

Which of the following is not used for excavation supports?

A)Sheet piles
B)Precast concrete piles
C)Contiguous bored concrete piles
D)Soil nailing
E)Soldier piles

Question 9

The four commonly used classifications of soils arranged in order of decreasing particle size are

A)gravel, sand, clay, and silt.
B)gravel, silt, clay, and sand.
C)gravel, silt, sand, and clay.
D)gravel, sand, silt, and clay.
E)none of the above.

Question 10

In terms of soil behavior in earthquakes, building codes classify a construction site based on soil conditions. The primary property of soil that is used in this classification is

A)the stiffness/density of soil.
B)the swelling and shrinkage characteristics of soil.
C)whether the soil is native to the site.
D)the size of soil particles.
E)none of the above.

Question 11

All testing of soil samples is generally done at the site

A)because the vibration of soil samples caused by transportation falsifies test results.
B)because modern soil sampling equipment is fully equipped with soil testing facility.
C)because the delay in bringing soil samples to the laboratory falsifies test results.
D)all of the above.
E)none of the above.

Question 12

Cohesive soils are those in which the dry soil particles tend to separate from each other when mixed with a small amount of water.

Question 13

Engineered fill refers to the soil that is

A)placed per the geotechnical engineer's specifications.
B)compacted per the geotechnical engineer's specifications and inspection.
C)specially formulated to provide the required properties.
D)all of the above.
E)none of the above.

Question 14

Sheet piles are used

A)as deep foundations in buildings.
B)as formwork for concrete walls.
C)as shallow foundations in buildings.
D)as excavation supports.
E)none of the above.

Question 15

The maximum presumptive bearing capacity value of bedrock provided by the International Building Code is

A)16.5 ksf.
B)12.0 ksf.
C)18.0 ksf.
D)15.0 ksf.
E)none of the above.

Question 16

A benched excavation is generally used

A)where the excavation depth is less than 5 ft.
B)on tight downtown sites.
C)on open suburban sites.
D)where dewatering of the site is not required.

Question 17

The bearing capacity of a soil is generally expressed in terms of

A)pounds or kips per cubic inch.
B)pounds or kips per inch.
C)pounds or kips.
D)pounds or kips per square inch.
E)pounds or kips per square foot.

Question 18

In the excavation support system using soldier piles, the soldier piles consist of

A)sheet aluminum.
B)sheet steel.
C)structural steel sections.
D)reinforced concrete.
E)precast concrete.

Question 19

To obtain soil- sampling tubes from below ground, which soil- testing method is commonly used?

A)Test boring method
B)Any one of the above
C)Test pit method
D)Test pressure method
E)None of the above

Question 20

If the bearing capacity of the soil is high, the footing area required is large.

Question 21

Dewatering of an excavation, as described in this text, can be done by the

A)pit method.
B)sump method.
C)well- point method.
D)A and B.
E)B and C.

Question 22

In the Unified Soil Classification System, the symbol M stands for

A)medium- grained soil.
B)soil of medium plasticity.
C)moist soil.
D)none of the above.

Question 23

Soil nailing refers to

A)a cut face of excavation supported by closely spaced steel bars and shotcrete over WWR.
B)a cut face of excavation supported by closely spaced steel bars or angles.
C)a cut face of excavation supported by closely spaced steel bars and shotcrete.
D)a cut face of excavation supported by closely spaced steel bars in grouted holes and shotcrete over WWR.
E)none of the above.

Question 24

In the soldier pile and lagging system, the lagging generally consists of

A)pressure- treated plywood.
B)pressure- treated lumber.
C)sheet steel.
D)structural steel sections.
E)none of the above.

Question 25

Ignoring the top vegetation, the composition of below- ground matter at a site is classified into two types: (i)soil and (ii)rock. What is the fundamental difference between the two?

Question 26

Soil is classified into two types based on particle size. Name the types and the particle size that separates the two types.

Question 27

Contiguous bored piles are constructed using

A)site- cast reinforced concrete.
B)precast, prestressed concrete.
C)precast concrete.
D)structural steel sections.
E)none of the above.

Question 28

Tiebacks used with the anchored soldier pile system of excavation support consist of

A)structural steel angle sections in grouted holes.
B)prestressing tendons in grouted holes.
C)prestressing tendons or reinforcing steel bars in grouted holes.
D)reinforcing steel bars in grouted holes.
E)none of the above.

Question 29

Explain what a No. 200 sieve is.

Question 30

An alternative to lagging that is commonly used with the soldier pile system of excavation support is

A)sheet steel.
B)shotcrete over welded wire reinforcement (WWR).
C)pressure- treated plywood.
D)structural steel sections.
E)pressure- treated lumber.

Question 31

In the Unified Soil Classification System, the symbol GP stands for

A)pea gravel.
B)poorly graded gravel.
C)peat and gravel.
D)soil with good performance.
E)none of the above.

Question 32

Name two items of information that a subsurface investigation of site provides to determine the cost incurred in excavating for foundations and basements.

Question 33

Name the architect's consultant who provides subsurface investigation of site.

Question 34

Coarse- grained soils are divided into two types based on particle size. Name the two types and the particle size that separates them.

Question 35

Which of the following soils has the lowest liquid limit?

A)Sand
B)Silt
C)Clay
D)Mixture of silt and clay
E)Mixture of silt and sand

Question 36

In terms of design and construction, secant piles are related to

A)sheet piles.
B)contiguous bored piles.
C)soldier piles.
D)none of the above.

Question 37

The center- to- center distance between secant piles is generally

A)15 to 20 ft.
B)10 to 15 ft.
C)8 to 12 ft.
D)5 to 8 ft.
E)none of the above.

Question 38

The expansiveness of a soil is determined from the values of

A)plastic limit and plasticity index.
B)plastic limit and liquid limit.
C)liquid limit and plasticity index.
D)none of the above.

Question 39

Existing site's topography (spot elevations of ground and ground contours)is an important part of site investigation to determine the site's suitability for the intended project. Is this a part of surface investigation or subsurface investigation?

Question 40

Construction site investigation consists of two parts: (i)surface investigation and (ii)subsurface investigation. Is investigating the site's natural drainage system and the site's likelihood to incur flooding a part of surface investigation or subsurface investigation?

Question 41

Explain what engineered fill is.

Question 42

Frost line is not considered in the design of buildings on a rocky soil. Why?

Question 43

Of the four types of soils-gravel, sand, silt, and clay-which of them are considered cohesive soils and which are considered noncohesive soils?

Question 44

What is the essential difference between contiguous bored piles (CBP)and secant piles as the excavation support system?

Question 45

Explain what backfill is.

Question 46

Fine- grained soils are divided into two types. Name the two types, coarser type first.

Question 47

In one of the methods of constructing cantilevered soldier piles for excavation support, the (outer)face of the wall is covered with pressure- sprayed concrete, referred to as shotcrete. What type of reinforcement is used in this method and how does it get embedded into concrete? Explain.

Question 48

In one of the methods of constructing cantilevered soldier piles for excavation support, the (outer)face of the wall is covered with welded wire reinforcement (WWR)on which concrete is pressure sprayed. In another method, WWR and concrete are replaced by an alternative material. What is that material?

Question 49

The test boring method is commonly used to obtain soil samples from various depths below the ground. The samples are transported to a geotechnical laboratory, where they are tested for various engineering properties of soil. In addition to obtaining soil samples for laboratory testing, the technician must record several pieces of information during the boring process. Name at least two of them.

Question 50

Explain the importance of frost line in building design.

Question 51

Unlike gravel and sand, whose particles are roughly the same size in all three directions (i.e., equidimensional), clay particles are flat (plate- like or flakes). This particle shape makes clay an unstable soil that swells with the addition of water and shrinks when dry. Explain the cause of this phenomenon.

Question 52

Explain what grading means with respect to earthwork.

Question 53

Explain what frost line is. Is it location specific?

Question 54

In which situation is the use of contiguous bored piles (CBP)as excavation support system considered?

Question 55

Two methods are used to support earth pressure on a basement wall. In one of these, the basement wall supports the earth pressure and is commonly used where the site is much larger than the building's footprint to allow open excavations. The second method is used on a tight site, where the building's footprint covers the entire site or most of it. What type of excavation support system is used in the second method?

Question 56

In which situation will the cantilevered soldier piles (as excavation supports)be provided with tieback anchors?

Question 57

The excavation support system using cantilevered soldier piles is constructed by drilling circular holes in the ground, placing a structural steel member in the holes and filling the holes with concrete. Which structural steel sections are used in this system?

Question 58

Explain what is included in surface investigation and subsurface investigation of a site.

Question 59

Explain what bearing capacity of soil is.

Question 60

The excavation support system using cantilevered soldier piles is constructed by drilling circular holes in the ground, placing H- shaped steel sections (referred to as HP sections)in the holes and filling the holes with concrete. Before the HP sections are placed in the holes, extruded polystyrene (EPS)boards are glued to the front and back side of the outer flanges of HP sections. What is the purpose of EPS boards?

Question 61

Explain the difference among (a)fine- grained soils and coarse- grained soils, (b)sand and gravel, and (c)silt and clay.

Question 62

Explain where self- supporting basement excavation may be used.

Question 63

Using sketches, explain the difference between cantilevered soldier pile and anchored soldier pile excavation support systems.

Question 64

List various excavation support systems commonly used.

Question 65

List the steps needed in the construction of a soil- nailed excavation support system.

Question 66

Explain the difference between how a stiff, dense soil and a soft, loosely compacted soil perform during an earthquake.

Question 67

Explain why the wall and column footings must be placed below the frost line.

Question 68

Explain why clayey soils are unstable.