Geotechnical Design Exam Review || with Complete Solutions.

What are indicator piles. and how do they benefit the foundation design process? correct answers 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? correct answers 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 newly-constructed drilled shaft foundations? correct answers 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 answers The at-rest pressure is that which acts on a wall that has not experienced any lateral displacement or 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.