Problem 1222 Coduto 2011 A 5 m thick fill has recently been

Problem 12.22 (Coduto, 2011) A 5 m thick fill has recently been placed over clayey wetlands to support a new highway. The groundwater table was at or near the natrual ground surface. Soon after the fill was completed, but before the paving began, a small landslide occurred in the fill and the underlying soils. Unfortunately, a sudden budget crisis stopped all work on the project and nothing has been done for ten years. At present, a new source of funding will permit construction to resume. The fill slope, at the time of its failure, can be assumed to have a factor of safety of 1.0. Is the factor of safety still equal to 1.0 at present? Will remedial construction definitely be necessary to increase the factor of safety? What should be done to evaluate this situation? Explain.

This is what my teacher is expecting:

For this problem, an answer comprised of a sentence or two will not be compelling enough to provide a proper solution to the question. Answers will be assessed on your technical content, clarity (is your explanation, analysis, information, etc. you convey easy to understand and well organized?), correctness (is your explanation free of gramatical and mechanical error?), and persuasiveness (does your explanation convey information leading the reader to believe you have sufficiently addressed the problem?).

Solution

Actually the fill is provide for the support the highway. There are three layers placed below the pavement surface such as base,sub base, sub grade layers. The pavement structure will be damaged even one of those layers are weak. Because of that we will make sure that every layer is so strong enough to bear the loads. The strength required for the fill applied over the lands depend on the structural formation of that land. Then we should apply the factor of safety for the fill according to the type of structural formation. Different lands require the fills of having factor of safeties. According to the problem, the fill slope is assumed to be having the factor of safety of 1.0 at the time of failure. It may not be equal to the present factor of safety. The structural formation of that wet land definitely is having many changes after 10 years. Then more factor of safety will be required than before. The coating of fill applying on the land surface should be increased to keep the more factor of safety. So that the structural formtion of the fill will become strong enough against the land slides. If necessary, the addition of binding materials in between the inner layers also can be required. Then the total structure can support the pavement surface for long time. It is difficult to find the problems in the structure, after providing the highway. We should apply different destructive and non-destructive tests on the soil surface. The required factor of safety will be less, when the structure is strong. No matter what is the nature of the soil surface, we should make the structure strong against the natural disasters. By following some above mentioned remedies, we can apply the fill over the lands in order to maintain the structure strong.