GEOTECHNICAL DESIGN EXAM REVIEW | QUESTIONS & ANSWERS (VERIFIED) | LATEST UPDATE | GRADED A+

1 GEOTECHNICAL DESIGN EXAM REVIEW | QUESTIONS & ANSWERS (VERIFIED) | LATEST UPDATE | GRADED A+ What are indicator piles. and how do they benefit the foundation design process? Correct Answer: Indicator piles are prototype piles that are constructed before the production piles. These prototype piles are typically evaluated using pile driving analyzers, load tests, or other means to evaluate their load capacity. The results of these evaluations are then used to guide the design and construction of the production piles. In many cases, the indicator piles also are used to support the structure. Many engineers believe the only disadvantage to over designing pile foundations is the additional cost of the pile materials. However, there is another important consequence of over design which can significantly affect construction cost and may even make the foundation impossible to build. What is this consequence and how can it be avoided? 2 Correct Answer: In addition to increasing materials costs, over designed piles are more difficult to install, thus increasing labor and equipment costs. In some cases, the additional labor and equipment costs, as well as the associated delays in the construction schedule, can be dis proportionally large compared to the additional capacity gained. These unnecessary costs and delays can be avoided by more precise designs and by the used of the various techniques of verification and redesign during construction. These measures help assure the as built foundation has sufficient capacity and performance, without being excessively over designed. Under what circumstances would you most likely require integrity testing of newlyconstructed drilled shaft foundations? Correct Answer: Integrity testing is especially important when using the slurry method of construction. Explain the difference between the active, at-rest, and the passive earth pressure conditions. Correct Answer: The at-rest pressure is that which acts on a wall that has not experienced any lateral displacement or 3 rotation. In other words, it reflects the horizontal stresses that were present in the undisturbed ground. The active pressure is that which acts on a wall that has moved a sufficient distance away from the back fill to fully mobilize the shear strength of the soil. The passive pressure is that which acts on a wall that has moved a sufficient distance into the back fill to fully mobilize the shear strength of the soil. Which of the three earth pressure conditions should be used to design a rigid basement wall? Why? Correct Answer: A rigid basement wall should be designed using at-rest pressure because it has not moved enough to develop the active condition. A pre-stressed concrete pile is being driven into a saturated cohesive soil with a hammer blow count of 17 blows per foot of pile penetration. Unfortunately, the pile driving rig breaks down before the pile reaches the required depth of penetration, resulting in a 15-hour delay. Once the rig is repaired, pile driving resumes but the blow count is now 25 blows per foot. Explain the primary reason for this change in blow count. 4 Correct Answer: Driving of the pile caused large shear stresses in the soil. Since the soil was a saturated cohesive soil, positive pore pressures were generated during driving and therefore decreased the effective stress and both the end bearing and side friction compared to static loading. During the delay, the soil had time to dissipate some of the excess pore pressure generated during driving and the affected soil was able to consolidate. The decrease in pore pressure and the consolidation increased the soil strength and thereby the pile capacity. This effect is known in practice as ground "setup" or ground "freeze". Sometimes pile driving contractors use predrilling when installing piles. This method consists of drilling a vertical hole that has a smaller diameter than the pile, then driving the pile into this hole. Could predrilling affect the side-friction resistance? Why? Is the diameter of the predrill hole important? Why? Correct Answer: Predrilling can definitely affect the side-friction resistance by loosening the soil and by reducing the lateral earth pressure. Both the size of the predrill hole and its depth are important. The danger in 5 predrilling is that it can reduce pile capacity if the predrilling is too long or the diameter of the hole is much larger than the pile. Ideally, the hole diameter should be smaller than the pile diameter and the length should be kept to a minimum. Why is it important for drilled shaft contractors to place the concrete soon after drilling the shaft? What detrimental effects can occur if the contractor waits too long before placing the concrete? Correct Answer: There are two potential detrimental effects which can be caused by delaying concrete placement. The first is related to reduction in lateral earth pressure. The drilled shaft construction process will always decrease the lateral earth pressure around the shaft. The longer time shaft is open, the greater the reduction, up to some limit (e.g., the active failure state of the soil around the shaft). The second potential detrimental effect is caving and squeezing of soils. The longer the shaft is open, the greater the possibility of soils entering the shaft through squeezing or caving. Both of these effects can reduce the capacity. 6 What is "block failure" in a group of piles and how does it differ from individual failure? Correct Answer: Block failure is the mode of failure where the pile group and the soil between the files moves as a unit, and the side friction resistance is developed along the perimeter of this unit. In contrast, individual failure is the mode of failure where each pile fails individually and the side friction occurs along the side of each pile. The toe bearing in block failure occurs along the base of the entire block, whereas in individual failure it occurs along the tip of each pile. What is a typical design group efficiency factor for piles driven into loose cohesionless soil without predrilling or jetting? How does predrilling and jetting affect this factor? Why? Correct Answer: A typical group efficiency factor without predrilling or jetting would be about 1. Values somewhat less than 1 should be used when predrilling or jetting is used. Explain why pile-driving formulas are not reliable, and why a wave equation analysis is a better choice. Correct Answer: Pile-driving formulas have proven to be very inaccurate because they do not properly account for energy 7 losses during driving and the dynamic resistance of the pile during driving. In contrast wave equation analysis models the dynamic process of driving a pile. It accounts for energy lost during driving and clearly separates the dynamic and static resistance of the pile during driving. This leads to a much more accurate estimate of the pile capacity compared to pile-driving formulas. Why does the Statnamic test use a relatively slow burning propellant rather than high explosive to provide the energy for the test? Correct Answer: There are two problems with high explosives. First, they generate extremely high stresses and would destroy the Statnamic test device. Second, they would generate a very short stress pulse. For pulse load tests to work, the duration of the loading pulse needs to be 50 to 200 milliseconds. The detonation velocity of high explosives ranges from 5,000 to 10,000 m/s. If the charge was 10 cm long (quite long) the total detonation time would be 0.01 to 0.02 milliseconds which is much too short a duration for a pulse load test. 8 A 14-inch square pre-stressed concrete pile is to be driven with a certain hammer. According to a wave equation analysis, the compressive driving stresses will exceed the maximum allowable values described in Table 12.5. What can be done to resolve this problem? Provide at least two possible solutions. Correct Answer: A thicker pile cushion will reduce the peak stresses in the pile, but there is a limit to how thick a cushion can be used. If the blow counts during drive are not excessive, that is well less than 100 blows/ft, it may be possible to use a smaller hammer or reduce time hammer energy if a variable stroke hammer is being used. If reducing time hammer energy leads to excessive blow counts, we should try using a hammer with a heavier ram and shorter stroke. This will keep the total energy level up but decrease time ram velocity and thereby the driving stresses. Finally if none of these work, we can try using a pile with greater cross section. What are the primary advantages of using laterally-loaded vertical piles instead of battered piles? Correct Answer: Contractors with the proper equipment can usually install them at a batter as steep as 4 vertical to 1 9 horizontal by tilting the pile-driver leads. However, these operations are not as efficient as driving vertical piles, so the production rate is slower and the equipment wears faster. Laterally loaded vertical piles are not subject to these problems. Battered piles form a very stiff foundation system. This is suitable when only static loads are present, but can cause problems when dynamic loads are applied, such as those imposed by an earthquake, or impact loads, such as those from ships. Laterally loaded vertical piles are much less stiff, and thus better able to accommodate dynamic loading. Why is it appropriate to use more conservative structural designs for foundations than for comparable superstructure members? Correct Answer: -The construction tolerances for piles are much wider and quality control is more difficult. -Piles are often constructed slightly off their planned location, which introduces unplanned eccentricities in the applied load. -In the case of driven piles, the driving stresses might be greater than those imparted by the design loads, and thus might control the structural design. -Piles can be damaged during driving, so the as-built capacity may be less than anticipated. 10 -Residual stresses may be locked into piles during driving, so the actual stresses in the piles after the structure is completed may be greater than those generated by the applied structural loads. -Concrete in drilled shafts, auger piles, and other cast-in-place foundations is not placed under ideal conditions, and thus may experience segregation of the aggregates, contamination from the soil, and other problems. What type of pile is least prone to damage during handling? Correct Answer: Due of their high strength and ductility, and high strength/weight ratio, steel piles are least prone to damage during handling. The toe bearing capacity in piles is similar to the ultimate bearing capacity of spread footings. However, the side friction capacity has no equivalent in spread footing design. Why do we ignore the friction acting on the side of spread footings? Correct Answer: Because the height of spread footings is very small compared to their width, the contribution of side 11 fiction would be small. Additionally, footings are placed relatively shallow where lateral earth pressures are low, also leading to low side friction. When designing shallow foundations, we add the weight of the foundation to the applied column load (for example, see Equation 5.1). However, with downward loads on piles, this weight is not explicitly computed (see Equation 13.4). Explain how we account for the weight of piles subjected to downward loads. Correct Answer: Shallow foundations are generally designed using gross bearing stresses which would include the weight of the foundation itself. Deep foundations are generally designed using net bearing capacities which do not include the weight of the piles themselves. Since capacity is defined in terms of net quantities, the weight of the piles is not included in the computation. A typical deep foundation project may include several hundred piles, but only one or two static load tests. Thus, the information gained from these test pile must be projected to the production piles. Describe some 12 of the factors that might cause the load capacity of the production piles to be different from that of the test pile. Correct Answer: -Proximity of the tested pile to time actual piles: Closer proximity should be more accurate -Variations in subsurface conditions -Variations in pile-soil interface: Especially if using cast-in-place piles -Group effects -Variations in construction methods The results of pile load tests are usually considered to be the "correct" load capacity, and all other analysis methods are compared to this standard. However, there are many ways to conduct load tests, and many ways to interpret them. Therefore, can we truly establish a single "correct" capacity for a pile? Explain. Correct Answer: It is impossible to determine a single "correct" value because there are simply too many unknown variables. However, it is possible to determine a single maximum allowable value by considering multiple tests, analysis methods, the consequences of failure, construction cost, and applying a reasonable safety 13 factor. The impact of these considerations can vary tremendously between job sites making the process much more of an art than a science as there is no one right way to balance the information. Why are spread footings usually made of low-strength concrete? Correct Answer: Low-strength concrete is less expensive, and typically does not require as much quality control as higher strength concrete. Thus, this choice makes the foundations less expensive to build. Because of the reduced strength, the footings will be thicker and heavier, but this is not a problem because this additional weight does not affect the dead load on other members. Explain the difference between the shape of the actual shear failure surfaces in footings with those used for analysis and design. Correct Answer: Full-scale loading tests indicate the actual shear surface projects downward from the column in a pyramid or cone shape. However, for analysis purposes we treat this surface as if it was vertical. This simplifying assumption makes the computations much easier. 14 Explain the reasoning behind the statement in Section 10.6: "Because of their large width, mat foundations on sands and gravels do not have bearing capacity problems." Correct Answer: The third terms in the bearing capacity equations presented in Chapter 6 indicate the ultimate bearing capacity increases as the foundation width increases. Thus, mat foundations have a higher ultimate bearing capacity than spread footing foundations. In addition, the bearing capacity factors are larger in sands and gravels, because their friction angle is larger. This also increases the ultimate bearing capacity. The combination of these two effects produces a very high ultimate bearing capacity for mats on sand or gravel, so bearing capacity failures are very unlikely. How has the development of powerful and inexpensive digital computers affected the analysis and design of mat foundations? What changes do you expect in the future as this trend continues? Correct Answer: Before powerful computers and software were available, it was necessary to analyze mat foundations using simplified "rigid models". These simplifications produced inaccuracies in the analyses. However, we now are able to perform more realistic analyses that consider the flexural resistance of the mat and use 15 more accurate representations of soil-structure interaction. Therefore, modem designs are more accurate and more reliable. This trend will probably continue as future research better defines the problem, and as the necessary software is developed. These changes will probably better address soil-structure interaction and three dimensional effects. A mat foundation supports forty two columns for a building. These columns are spaced on a uniform grid pattern. How would the moments and differential settlements change if we used a nonrigid analysis with a constant k in lieu of a rigid analysis? Correct Answer: A non-rigid analysis would indicate more settlement beneath the columns and beneath the center of the mat, and less elsewhere. In addition, the non-rigid analysis would produce different moments in the mat because the soil bearing pressure will be higher under the columns and smaller between columns than indicated by a rigid analysis. Discuss some of the primary advantages and disadvantages of the following types of piles and suggest a potential application for each: -Timber -Steel 16 -Pre-stressed concrete Correct Answer: Timber: Advantages-Inexpensive, especially if near a forested area, Naturally tapered, Good for impact loads, such as from ships Disadvantages- Limited length, Low strength, Rapid deterioration, Subject to damage during hard driving, Not economical to splice Potential application-Docks and wharves Steel: Advantages- High capacity, Easily spliced or cut off, Can be driven into hard soils with heavy hammers Disadvantages- Expensive, Corrosion potential in waterfront applications Potential applications-Heavy bridges and buildings Concrete: Advantages-High capacity, Often less expensive than steel, Resistant to chemical and biological attack Disadvantages- Subject to damage during handling and driving, Expensive to splice or Cut off Potential applications-Bridges and buildings What is predrilling and when might it he used? What might happen if the predrill diameter or length was excessive? Correct Answer: Predrilling consists of drilling a hole into the ground, then driving the pile into the hole. This technique is useful in hard soils and permits the use of a smaller hammer, thus protecting the pile from damage. The 17 predrill hole must be smaller in diameter than the pile, and usually does not extend to the full depth of pile embedment. If the predrill hole is too large, the skin friction capacity of the pile will be significantly reduced, lithe predrilling is too deep, then the roe bearing capacity will be diminished. What type or types of piles would be appropriate to support a heavy structure on an undulating bedrock surface located 25 to 40 m below the ground surface? Assume the side friction in the overlying soils provides less than 20 percent of the total axial load capacity. Explain the reasons for your choice. Correct Answer: Steel piles would be the best choice for this project for the following reasons: 1. The piles are too long to drive in one piece, and therefore must be driven in sections. These sections must be spliced together in the field during driving. Steel piles are best suited to splicing. 2. The structure is heavy, and steel piles can carry heavy loads. 3. The bedrock surface is undulating, so the exact length of the piles is difficult to predict. Therefore, the piles must be driven to refusal, then any excess length must be cut off. Steel piles can be cut touch more 18 easily than concrete piles. Why are most concrete piles prestressed instead of being conventionally reinforced? Correct Answer: Prestressed concrete piles are better because they have much more flexural strength, and thus are less susceptible to damage during handling and driving. They also can carry larger lateral loads. In the context of pile construction, what are cushions, when are they used, and what is their purpose? Correct Answer: All impact-style pile hammers use a hammer cushion, to soften the sharp blow from the ram. Thus, the force acting on the pile has a lower intensity, but a longer duration. This protects the pile, but reduces the efficiency of the hammer. Concrete piles are more susceptible to damage during driving, and therefore require a pile cushion to provide additional softening. Pile foundations that support buildings usually have at least three piles for each column. Why? Correct Answer: The construction tolerances for placement of piles are wider than those for building the superstructure. 19 As-built piles easily could be 6 inches away from their intended locations. Therefore, columns supported on only one or two piles are likely to have large eccentricities, which cause unwanted flexural stresses in both the piles and the columns. However, if three or more piles are present, the eccentricities are small compared to the size of the pile group. Eccentricities between the center of the column and the center of the pile group are then much less significant. Pile driving in loose sands without predrilling tends to densify these soils. What effect does this densification have on the load bearing capacity of such piles? Correct Answer: Pile driving tends to densify loose sands. This densification increases the soil strength, and thus increases the load-bearing capacity. Describe two situations where a drilled shaft would be preferable over a driven pile, then describe two situations where the reverse would be true. Correct Answer: Drilled shafts would probably be preferable in the following circumstances: -The project is small, so the cost of mobilizing and demobilizing a pile driver would be spread out over fewer piles. 20 -The project site is especially sensitive to construction noise and vibration (e.g.. Sensitive computer equipment in an adjacent building). Piles would probably be preferable in the following circumstances: -The foundations must extend through water (e.g., a pier or dock). -The foundations must extend through thick strata of very clean, saturated sands (difficult to build drilled shafts without caving problems). In what circumstances would you expect caving or squeezing conditions to be a problem? What construction methods could a contractor use to overcome these problems? Correct Answer: Caving can be a problem in loose sandy soils, especially when they are beneath the groundwater table. Squeezing can be a problem in soft silts and clays. Both problems can be overcome using special construction techniques, such as casing or drilling slurry. The dry method of drilled shaft construction is most suitable for which types of soil conditions? Correct Answer: The dry method is most suitable for soils that do not have potential caving or squeezing problems. This 21 would include stiff silts and clays, and dense sandy soils with sufficient fines to maintain stability of the hole. There are many ways to build midstream foundations for bridges that cross rivers and other bodies of water. One of them is to use a caisson, as described in this section. Another is to drive piles from a barge. Suggest some advantages and disadvantages of these two methods. Correct Answer: The caisson method produces a large monolithic foundation, and thus is well suited for heavy bridges. This method also has the advantage of exposing the bearing soils during construction, thus removing some of the uncertainty. However, fabrication of the caisson can be expensive, and requires special facilities that may not be readily available. The pile method can be implemented using standard construction equipment. In addition, piles can penetrate to greater depths, and thus are useful when the shallow soils are not suitable. However, piles do not have as much flexural capacity, and thus may be more difficult to use when large lateral loads are present. 22 Both methods have been successfully used. Suggest some critical items that a Construction inspector should watch for during the construction of auger-cast piles Correct Answer: The inspector should monitor the rate of auger withdrawal vs. rate of grout injection. If the auger is withdrawn too quickly, the pile can become contaminated with soil. The quality of the grout, including cement content and water-cement ratio. It may be appropriate to retrieve samples for laboratory testing Pressure-injected footings are best suited for sandy or gravelly soils with less than about 15 percent fines. Why would this construction method be less effective in a stiff saturated clay? Correct Answer: One of the advantages of pressure-injected footings is that the process of making the bulb densifies the surrounding soils, thus improving their load-bearing capacity. This densification is most pronounced in clean sands and gravels. Unfortunately, much less densification occurs in saturated clays, because the rate of loading is faster than the rate of drainage (i.e. an undrained condition exists). 23 A proposed ten-story office building is to be supported on a series of deep foundations embedded 60 ft below the ground surface. The soils at this site are loose to medium dense well-graded sands (SW) and silty sands (SM), and the groundwater table is at a depth of 12 ft. What type or types of deep foundations would be most appropriate for this project? What type or types would probably not be appropriate? Explain the reasons for your selections Correct Answer: Precast-prestressed concrete pile foundations would be a good choice for this structure. These piles should drive well through these soils, and provide excellent load-bearing capacity at a reasonable cost. Pressure-injected footings also would be a possibility, because these soils would densify during construction of the bulb. These soils will probably have caving problems, so drilled shafts will probably not be as economical. A new reinforced concrete pier is to be built in a major harbor area. This pier will service ocean-going cargo ships. The underlying soils are primarily low plasticity silts (ML) and clays (CL). with some 24 interbedded sand layers. What type or types of deep foundations would be most appropriate for this project? What type or types would probably not be appropriate? Explain the reasons for your selections. Correct Answer: Pile foundations are probably the only practical method of support for this pier. Timber piles could be used to take advantage of their impact resistance, but they eventually would need to be replaced and the concrete deck would make replacement difficult. Therefore, precast-pre-stressed concrete piles would probably be a better choice. Drilled shafts, auger-cast piles, and pressure-injected footings would be virtually impossible at this site because the ground surface is located underwater. Which method of expressing footing width criteria (allowable bearing pressure or design chart) would be most appropriate for each of the following structures? a. A ten-story reinforced concrete building b. A one-story wood frame house c. A nuclear power plant d. A highway bridge Correct Answer: a. Design chart 25 b. Allowable bearing pressure c. Design chart d. Design chart or design each footing individually Explain why an 8-ft wide footing with q = 3000 lb/ft2 will settle more than a 3-ft wide one with the same q. Correct Answer: The induced stresses for the 8-ft wide footing penetrates much deeper into the ground than those for the 3- ft wide footing. Therefore, more of the soil is subjected to an increase in stress, and more of the soil will experience a vertical strain. This translates to more settlement in the larger footing. Under what circumstances would bearing capacity most likely control the design of spread footings? Under what circumstances would settlement usually control? Correct Answer: Bearing capacity will most often control when the footing width is small or when undrained conditions prevail. Settlement is more likely to control when the width is large, especially in sandy or gravelly soils. A proposed building will have column loads ranging from 40 to 300 k. All of these columns will be 26 supported on square spread footings. When computing the allowable bearing pressure, qA, which load should he used to perform the bearing capacity analyses? Which should be used to perform the settlement analyses? Correct Answer: The hearing capacity analysis should he performed using the 40k load, while the settlement analysis should use the 300 k load. A compacted fill is to be placed at a site in North Dakota. The following soils are available for import: Soil 1 -silty sand; Soil 2 - lean clay; Soil 3 - Gravelly coarse sand. Which of these soils would be least likely to have frost heave problems? Correct Answer: Soil 3, the gravelly coarse sand, would be least susceptible to frost heave. Would it be wise to use slab-on-grade floors for houses built on permafrost? Explain. Correct Answer: Slab-on-grade floors would not be a wise choice because they transmit heat from inside the house to the underlying ground, and this heat would eventually melt the permafrost. A raised floor with a vented airspace between the floor and the ground would be a better design. 27 What is the most common cause of failure in bridges? Correct Answer: Scour of the soil around and beneath the foundations. A single-story building is to be built on a sandy silt in Detroit. How deep must the exterior footings be below the ground surface to avoid problems with frost heave? Correct Answer: Per Figure 8.15, the depth of frost penetration in Detroit is about 50 inches. Therefore, the footing should be embedded to at least this depth. The consolidation settlement computations described in Chapter 3 considered z, to be constant with depth. However, in this chapter,z, decreases with depth. Why? Correct Answer: When the loaded area is wide compared to the depth to the bottom of the compressible stratum (as described in Chapter 3), then z is nearly constant with depth. However, when the loaded area is relatively small (as described in Chapter 7), the applied load spreads out with depth in a cone or pyramid fashion. Therefore, z decreases with depth. Examine the stress bulbs for square and continuous footings shown in Figure 7.2. Why do those for 28 continuous footings extend deeper than those for square footings? Correct Answer: The pressure bulbs for continuous footings penetrate deeper than those for square footings. This means that z is larger at a given depth beneath a continuous footing than it is at the dame depth beneath a square footing with the same width and bearing pressure. This occurs because the applied structural load dissipates in only one direction (i.e. perpendicular to the footing) with depth below a continuous footing, while beneath a square footing it dissipated in two directions with depth. What is the difference between a square footing and a continuous footing and when would each type be used? Correct Answer: A square footing is one that is square in plan view. They are typically used to support a single column or bent. A continuous footing is a long strip (in plan view) and is most often used to support a bearing wall. List the three types of bearing capacity failures and explain the differences between them Correct Answer: -A general shear failure has a well-defined shear surface below the footing, with relatively little volume change in the soil. A well-defined bulge occurs in the surrounding soil. 29 -A punching shear failure has localized shearing immediately below the fooling, but involves much more compression of the soil. Because of this compression, there is little or no bulge in the soil. -A local shear failure is an intermediate case that is between a general shear failure and a punching shear failure. Discuss the-advantages of the cone penetration test over the standard penetration test. Correct Answer: -The test procedure is more repeatable and less subject to operator technique. -The test has much better resolution since it produces a continuous plot of the test results vs depth, while the SPT produces only one N value every couple of feet. -The superior data from the CPT allows the engineer to conduct more precise analyses. A certain clayey soil contains 0.30 percent sulfates. Would you anticipate a problem with concrete foundations in this soil? Are any preventive measures necessary? Explain. Correct Answer: According to Table 2.3 one could expect severe problems with sulfates. According to Table 2.3, the preventive measures would be to use type V cement with a water-cement ratio of less (or equal) than 0.45 30 A series of 50-ft long steel piles are to be driven into a natural sandy soil. The groundwater table is at a depth of 35 ft below the ground surface. Would you anticipate a problem with corrosion? What additional data could you gather to make a more informed decision? Correct Answer: The situation will probably not pose a problem. It would be convenient that the piles will not be exposed to salt water (e.g,, if sandy soil is close to the sea). Consider a soil that is being placed as a fill and compacted using a sheeps foot roller (a piece of construction equipment). Will the action of the roller change the void ratio of the soil? Explain. Correct Answer: The volume of solids remains constant, but compaction reduces the total volume and thus reduces the volume of the voids. (The action of the roller) will result in a lower void ratio. Explain the difference between the drained condition and the undrained condition Correct Answer: If the rate of loading is slow enough that pore water can freely move into or out of the voids, then little or no excess pore water pressures develop. This is known as the drained condition. The opposite extreme 31 occurs when the rate of loading is so fast that, at least for a short time, little or no water moves in or out of the voids. This situation produces excess pore water pressures and is known as the undrained condition. The characterization of loading as being "fast' or 'slow" depends on the hydraulic conductivity, the distance to the nearest drainage boundary, and other factors. Soils also can be in an intermediate partially drained state Which laboratory tests would be appropriate for finding su of a clay? Correct Answer: Unconsolidated-undrained triaxial test. Unconfined compression test. Which laboratory tests would be appropriate for finding 'f a sand? Correct Answer: Consolidated-drained triaxial test Direct shear test Name some shallow foundations Correct Answer: Spread footings Mats Name some deep foundations 32 Correct Answer: -Piles -Caissons -Driven Piles -Drilled Shafts -Mandrel-Driven Thin-Shells Filled with Concrete. -Auger-Cast Piles. -Pressure-Injected Footings. -Pile-Supported and Pile-Enhanced Mats. -Anchors Type of load (D) Correct Answer: Dead Load Type of load (L) Correct Answer: Live Load Type of load (Di) Correct Answer: Weight of ice Type of load (Lr) Correct Answer: Roof Live Load Type of load (S) 33 Correct Answer: Snow Load Type of load (R) Correct Answer: Rain Load Type of load (H) Correct Answer: Earth Pressure Loads Type of load (F) Correct Answer: Fluid Loads Type of load (Fa) Correct Answer: Flood loads Type of load (E) Correct Answer: Earthquake Loads Type of load (W) Correct Answer: Wind Loads Type of load (T) Correct Answer: Self-straining Load