A New Highway Construction Issues - Coursework Example

 A New Highway Consider the construction of a new highway whose centre line is shown between locations A and B. The carriageway will be at a level of 50m above Ordnance Datum at A, climbing uniformly to 70m above Ordnance Datum at B. Produce a report, illustrated with appropriate geological section(s) and any other figures you consider useful, that describes: a) the geology of the area; (481 words) The geology of the area in question where the carriageway is going to be built has a variety of features which should be of some interest to the contractor as well as the organisation that wants this carriageway built. First of all, the landscape varies considerably in both size and the material out of which it is shaped. For example, there is an embankment that rises from almost sea level to up to 125 meters in height as one continues to move west. Interestingly enough, the way the landscape is actually formed—as one moves west from the east—the types of material of which the ground is made changes. On the topographical map, it can be seen that, a little bit below each bell curve, is a line where each new material begins to take place. There are five different types of material of which the ground is composed. The first type of material, nearest the lowest point of the embankment—near sea level—is called alluvium. Alluvium basically means that it is sediment deposited from water that has passed through the area. Alluvium is “river-deposited sediment; sorted and bedded, but any grain size from clay to boulders; [it is] laterally and vertically variable, with a wide range of engineering properties.”1 One of the main problems with the embankment being so close to the alluvium deposits is that this is not necessarily steady ground on which to build a carriageway. Luckily, the next element to be discussed is a bit more sturdy. The second type of material to be discussed is limestone. Limestone is a very hard material. “Limestone is a popular material for the outer walls of buildings. Thin sheets of limestone are used to decorate the outside of some modern buildings. Ground-up limestone that is mixed with clay and baked forms cement.”2 The third type of material to be discussed is shale. One needs “…the lowering of ground water levels below the level of the oil shale strata.”3 The fourth type of material to be discussed is sandstone. “Sandstone is a sedimentary rock group which is mostly made up of tiny grains of quartz. Most sandstone is formed in oceans, lakes and rivers where tiny bits of rock and dirt settle to the bottom. Year after year, these layers of sand get buried under tons of more sand and dirt until it is turned into solid rock.”4 The fifth type of material to be discussed is dolomite. Dolomite is “[u]sually found as druzes or clusters of small rhombohedral crystals with a somewhat saddle-shape[d], white to tan to pink in color.”5 Dolomite is a very interesting rock. “Dolomite, like calcite, cleaves into six-sided polyhedrons with diamond-shaped faces. Relations between lamellar twinning and cleavage planes of dolomite, however, differ from those of calcite…, and this difference may be used to distinguish the two minerals in coarse-grained rocks such as marbles.”6 b) the possible problems that the geology may pose for the construction of the highway and associated structures such as embankments, bridges or cuttings; (540 words) The possible problems that the geology may pose for the construction of the carriageway includes the fact that the carriageway is 70 metres high and the actual land, at one point, is 75 metres. This may interfere with the way the carriageway is built. Some land may have to be sheared off in order for the carriageway to fit properly across the space available for the carriageway. It is preposterous that the contractor would have to build a carriageway where there is no available space. If the land does indeed have to be sheared off, there will be a variety of heavy earth-moving equipment that might have to be employed. In other words, basically if what the contractor is looking at involves having to move a lot of earth, it is possible that the organization building the carriageway might choose to have the carriageway built in another location. This indeed might have to be the case if, in fact, the main problem is that the land is too high with regard to the carriageway. This could cost the organization time, as well as money. Also, it might be a difficult task for the contractor to have to totally reshape one portion of the land, especially if it is built of limestone and is very hard. That would require a lot of heavy moving equipment and a great deal of trouble on the part of the contractor, as stated previously—but what is most detrimental to the entire project would be the cost of moving all this earth, which is basically made of limestone. Probably the contractor would need special tools used in quarrying, which would facilitate the earth being shaped (or sheared off) by about 5 metres. This would pose a large problem for the organization building the carriageway, because the equipment that is used in quarrying is generally very expensive. It could easily cost hundreds of thousands of units of currency in order to purchase the proper equipment needed in order to shape the embankment to a more efficient form. Quarrying equipment include conveyor belts, rock crushers, sorters, cranes, bulldozers, drills, dynamite and other explosives, rock drills, drag lines, bucket-loaders, and dump trucks. All of this equipment could cost millions in total. Quarrying work can be very strenuous on workers who are trying to shape the land. Using explosives is dangerous, but in order to carry out the mission of shaping the land, most likely they will have to be used. Usually, controlled explosions are utilized in order to shape geography. Demolition experts will probably carry out such kinds of operations. Demolition experts are trained to be able to use explosives in a constructive way. Such experts know how to control explosives so that they detonate in key specified areas. Usually, what will happen is that the demolition experts will basically cordon off a part of land that they want gone, and then they will work diligently in order to ensure that this part is gone once it is blown up. After having decided how they are going to get rid of a particular piece of land, the demolition experts will then leave it up to the contractor how they want to use the extra land, if at all. c) possible geological sources of materials within the map area which could be used in the construction of the highway and its associated structures. (479 words) The best possible way in which materials could be used on the construction of the highway is if builders use the limestone that is blown off in order to make cement. As may have already previously been known, limestone is one of the minerals used in making concrete. Basically, it is one of the key ingredients. The limestone could be blown off the embankment with explosives, and then be used in order to make cement. In addition, another rock that could be used in the cement of the road would be dolomite, since it is a very hard mineral. Dolomite is usually clear, white, or grey in colour, so it would mix in with the other minerals (including limestone) very nicely. Also, sand would probably have to be mixed into the cement in order for it to become useful at all. Therefore, in total we have limestone, dolomite, sand, and other materials mixed into cement in order to form the carriageway. Of course, this would include a lot of digging on the behalf of the organization doing the construction. Of course, it makes the most sense that this stone would have to be quarried out by using a variety of tools and machines. This would take awhile to do such construction. This might take anywhere from three months to a year, depending on how quickly the machines could operate and manpower could be utilized. In other words, there would have to be a lot of operations going on at the same time in order to coordinate the building of the carriageway. For example, it would be necessary for the dolomite to be quarried at the same time that the limestone was being quarried as well. Once both of the minerals were acquired, they could be mixed into the cement and effectively be used in the building of the carriageway. It is important to note that these minerals would have to be, in effect, crushed very finely in order to make a very good, solid carriageway that would be well-cemented. This carriageway would be built to specifications in order to make sure that the embankment being 75 metres high would not encroach upon the highway itself. Luckily, the carriageway would not be built on sandstone, which is not as stable as a material as shale, which reinforces the limestone. Thus, it would be a great idea if all the available materials that were necessary for making the cement were placed into one area that could be designated the mixing area. This would be cordoned off from the rest of the construction project. Then, cement trucks could bring the cement to lay the foundation for the carriageway. It would be necessary to try to coordinate all of these movements in order that every step of the operation could be carried out properly, in due order. This would be the ideal scenario. Coursework Part 2 Three samples have been submitted for testing and you are required to carry out laboratory tests and to produce a report describing the tests, summarising the results and addressing the specific issues raised for each sample as follows: Sample A This is a sample of imported clay which it is proposed to use for embankment construction. The specific gravity of the soil particles can be taken as 2.70. The Contractor will be required to compact the material to 95% of its maximum dry density. 1. Carry out a compaction test to BS1377 to determine the maximum dry density and optimum moisture content. (150 words) It is obvious through looking at the compaction test that the mass of mould plus soil fluctuates as time goes on. Meanwhile, it also has become apparently obvious that the moisture content varied considerably, also in conjunction with the way that the mass of the mould plus soil varied. The mass of the tin (in grams) also fluctuated too. The maximum dry density would have been 57.9 grams, since one has to take the mass of the tin away from the mass of the dry soil plus tin with all the data and find the maximum amount of density. The optimum moisture content was 68.1 grams. This was calculated by taking the mass of the tin away from the mass of the wet soil plus tin. These figures were calculated by simply using subtraction in order to find out the maximum dry density and the optimum moisture content, both respectively. 2. The in-situ moisture content of the stiff clay layer is about 14%. Will it be possible for the Contractor to achieve the required level of compaction. If not, discuss measures and their effectiveness for adjusting the moisture content of the material. (150 words) The contractor will not be able to achieve the required level of compaction necessary. In order to do this, the contractor must take measures in order to adjust the moisture content of the soil. Most likely, the contractor will have to make the soil wet enough so that it will be able to absorb the liquid and thereby be able to be compacted into a tighter space. Without a doubt, the contractor will probably use water as the liquid which will be added to the soil. Water has a neutral pH balance, and it is also the most obvious liquid that might be added to the soil without changing the content and texture of the soil. Most likely, the required level of compaction will definitely be achieved once the soil is wet enough in order to manipulate. Adding liquid to the soil will add moisture content to the soil mixture. 3. What other soil parameters should be investigated to determine the suitability of this material for its proposed use? (159 words) The other types of soil parameters that should be investigated in order to determine the suitability of the material for proposed use is to: 1) take test samples of all the materials of which the ground is made; 2) have the test samples analysed; and 3) have experts project which material might be best with which to help proffer the construction of the carriageway. First, test samples of all the materials should be taken. This will ensure that all of the types of ground are thoroughly sampled, both with wet and dry soil. Next, all of the test samples should be thoroughly analysed. Finally, experts should be able to determine how to best use all the different types of soil--whether they be wet or dry—in the construction of the carriageway. It is imperative that the experts pay close attention to the mass of the soil and its ability to compact, so that there will not be problems. Sample B This is a sample of the river terrace deposit which it is proposed to use as drainage material. The specification requires material being used for this purpose to have grading falling within the envelope defined by the following: Sieve mesh size (mm) 20 5 1.18 0.6 0.15 Percentage passing (%) 100 60 - 100 15 - 45 0 - 25 0 - 5 1. Carry out a sieve test to determine whether the material meets this specification requirement. (141 words) The sieve test has determined, that, basically with a sieve below 1.18 mm in size, the drainage material is going to have a difficult time passing through the sieve. What is troubling about these results is that, if the sieve is too small through which the drainage material needs to pass, this could be problematic for the drainage system. The material needs to be fine enough so that it can pass through the drainage system. If this is not possible, there could definitely be problems in the future with blockages in the drains. In order for this material to be successfully used as drainage material, it might have to be ground more finely or have a bigger sieve used in the test in order to make sure that the specification requirements match what is being used in the selected test samples. 2. Discuss possible sources of error in the sampling and testing procedures. (150 words) Possible sources of error in the sampling and testing procedures could have included the moisture content of the soil. If the soil was sampled early on in the morning, dew could have accumulated on the soil, and soaking in. Thus, this would make the sampling skewed as normally, dew evaporates into the air after the morning is over. Additionally, there could have been errors made by the person who is taking the sample. If there is water mistakenly poured into the sample, the sample may have more or less ability to be compacted, depending on how much moisture is present in the soil sample. The importance of being able to take an untainted soil sample is paramount. If the soil is affected in any way that is not pursuant to ideal conditions, this could negatively affect the sampling and testing. It should be noted that errors do occur very frequently. 3. What other soil parameters should be investigated to determine the suitability of this deposit as a drainage layer? (157 words) Other soil parameters that must be taken into account in order to determine the suitability of the deposit as a drainage layer include the moisture content of the soil, how gravity is affecting the soil’s density, and how well the soil can be compacted. The moisture content of the soil is directly affected by how much liquid has been absorbed by the soil. Another factor that must be taken into consideration is how gravity is going to play a part in the density of the soil. Thirdly, the soil can only be compacted as well as it has the ability to move, which is affected by how much liquid is infused into the soil. As such, the moisture content of the soil, thus, affects the suitability of this drainage deposit as a drainage layer on two fronts. Thus, one can see that the ability to compact the material is compounded by the in-situ moisture of the soil. Sample C This is a sample of the alluvium which it is intended to use as general fill. 1. Determine the liquid limit, plastic limit and plasticity index of this material and classify the material. (197 words) The liquid limit was calculated as approximately 12.5% by taking the mass of the container with the soil at its lowest and highest limits, then taking the mass of the container and dividing it by the overall mass, in order to gain a percentage that would most accurately estimate the liquid limit. The plastic limit was calculated as 9.8% by finding the mass of wet soil versus dry soil by subtracting the weight of the container. Then, this number was divided by the highest weight in order to find the plastic limit. The plasticity index was calculated as 10% by taking the highest differences between the mass of the wet versus dry soil after the mass of the container had been subtracted from both. As one can see, the plastic limit is very close to the plasticity index. The liquid limit, plastic limit, and the plasticity index all being calculated will definitely help the contractor in trying to decide how to best approach the situation regarding compacting both wet and dry soil. If the soil needs to be irrigated prior to construction of the carriageway, having taken these samples will better help the contractor to estimate this. 2. The material has an in-situ moisture content of about 55%. Taking into account this and the results of your laboratory testing, discuss any problems that the Contractor may have in using this material. (200 words) The difficulty that the contractor may have in using a material that has an in-situ moisture content of about 55% would severely limit the contractor’s ability to manage the soil at the site where the construction would be completed. Basically, what the contractor is concerned about is the ability to, in effect, effectively move material. Materials that are highly-saturated with moisture may be very difficult to move and thus might not be desirable material in order to build a carriageway. As such, it is an important factor in the construction process to have samples tested and retested to ensure that, first of all, the in-situ moisture content is correct. Once it has been confirmed that the moisture content is indeed correct, then it is up to the experts to determine how to best manipulate the moisture content (if it can be manipulated) in order to ensure that the contractor can still go ahead with the construction process. If the high moisture content is still a problem, the contractor may have to find other material or materials in order to facilitate the building of the carriageway. While research is being conducted, the contractor should be weighing other alternatives for building materials. SUMMARY (96 words) In order to best calculate the necessary wetness of the various types of soil that would have to be compacted for the construction of the carriageway, it is imperative to note that the soil would have to be sampled and tested at various stages of its resting state. Obviously, there are various factors which would affect the liquid limit, plastic limit, and the plasticity of the soil. Using the data given, it is possible to analyse how the carriageway would best be built, considering the embankment that would threaten to derail the entire construction project entirely. WORKS CITED Anon. Oil Shale Magazine, Vol. 20, No. 1. Estonia: Estonian Academy Publishers, 2003. Pp. 86. Anon. Physical Properties. Encyclopedia Britannica Online. http://www.britannica.com/EBchecked/topic/168322/dolomite/80166/Physical-properties Retrieved 24 Dec 2010. Pgh. 1. Ralph, Jolyon. Dolomite. http://www.mindat.org/min-1304.html. Retrieved 24 Dec 2010. Pgh. 1. Sandstone. http://www.mineralszone.com/stones/sandstone.html. Retrieved 24 Dec 2010. Pgh. 1. Stille, Darlene R., et al. Sedimentary Rocks: A Record of Earth’s History. U.S.: Compass Point Books, 2008. Pp. 3. Waltham, Tony. Foundations of Engineering Geology. U.S.: Taylor & Francis, 2009. Pp. 32. Read More