Advanced Technology: Planning & Production - Essay Example

Advanced Technology: Planning & Production Students Name: Student Number: Course title: University: Department: Unit Number and Title: Lecturer: Submission date: Task1 Ground Improvement Purposes of ground improvement methods Ground improvement is the alteration that is controlled by nature or depending on the behaviour of the materials on the field, and it is intended to meet the projected engineering and environmental actions. Reclamation of land and making it to be of good use requires usage of suitable fill material made from high quality. This can provide reasonable haulage distance. To improve the fill masses of the required land, ground improvement is necessary since it is affordable and allows room for improvement (Chudley, et al. 2011, 76). If after land reclamation, some of these properties have defects. Then land development becomes the simpler option to use to repair the problem (I.C.E., 2003, 58). Additionally, in cases like road construction and repairs it is hard to implement land development; however, using the possible improvement measures it is noble to do reclamations for any future road structure. Vibration does Main ground improvement techniques, grouting, admixtures, structural fill, adding load, dewatering, and structural reinforcement (Bryan, 2010, 78). These techniques are used to remove such contaminants like hazardous wastes, non-hazardous wastes, special waste, contaminated sludge, and contaminated liquids. Improvement techniques Temporary: -in this technique, ground improvement is only done only when the application is required, for example, ground freezing and dewatering. Long-term: -this technique is used in areas where they ease congestions for longer benefits, for example, use of diaphragm walls or grouting. Short-term: -in this type of treatment the treatment in for permanent improvements, for instance, vibro-replacement, soil nailing, and dam curtain grouting. Factors affecting ground treatment Size of the area required for development; Distance from the existing buildings; Safety and access considerations; Treatment plant/equipment availability; and Cost of the treatment plant. Study cases Contaminated ground Considering the case of The Olympic Park, there was soil cleaning to control the 2.5km2 areas that had its waterways contaminated and choked. The task started with the head of an infrastructure. This was an implication that there was proper task management where depth desk surveys are conducted an extensive analysis done. From the investigation, the ground was found to have non-hazardous wastes and contaminated sludge that clocked the entire area. During this project, an excavation of 2.3 million m³ and 800,000 m³ of soil was washed out using five soil-cleaning machines (Chudley, et al. 2011, 89). Nevertheless, numerous treatments like bioremediation (where oxygen helps in accelerating waste breakdown by bugs) and exploration of stabilization technologies. Improvement in bearing capacity This case study investigates the means through which silty clay soil bearing capacity where it has a thin sand layer on upper side and laying geogrids at varying depths. In this case, study model tests were done on a footing that was rectangular placed on top of the soil to determine the load against curves of reinforced and unreinforced soil system. In this study, the results of the test focuses on improvement of bearing capacity for sand and silty clay that was used in the reinforced and unreinforced soil system in a form that is non-dimensional (Kyle, and Dimitrios, 2012, 275). From these results, it is clear that, as the numbers of geogrids layers increase so does the bearing capacity increase. An increase on the average of about 16.7% was recorded where a geogrid is used with layer interface of 0.67 increasing the percentage to 33.3% where the geogrid layer of 0.33 is used. Task 2: Subway Construction Traditionally, construction of a subway has three phases of development. In constructing, the pedestrian subway is to be constructed as part of the new Asian Business Park to the west of the University three steps will be used in the design, the initial phase includes budget, the second phase is planning and the third stage entails all the implementation procedures (Ashworth, 2007, 78). A typical section through the construction used in the design employs the traditional technique of constructing the road crossing subway within a battered excavation. In this layout, method used for the subway construction is cut and cover method, where the road bridge requires excavation as well as temporary works in the process of the development. Cut-and-cover method of subway construction This process entails the use of four types or processes used in the design. These methods include, conventional method, cast in place method, top-to-down method, and bottom-up method (Chudley, et al, 2011, 67). In this design, bottom-up in the type of cut-and-cover subway construction process that will be used in the design. In the bottom-up cut and cover design, the caisson wall in installed using a drilling rig to the existing bedrock (see figure 1). After the caisson installation is complete, the excavation is done to remove the soil between the walls up to a depth below where the tunnel floor should reach (see figure 2). A slab is poured to construct the tunnel floor, and then the walls are built from bottom up at the sideways of the tunnel (see figure 3). The roof of the tunnel is formed after the walls have been completed then the ground on the top of the tunnel, which is the road way is reinstated (see figure 4). Best materials used in the construction may include concrete, corrugated steel arches, pre-cast arches or pre-cast concrete. However, in this design the material used is specific. Constructing a subway using the cut-and-cover method requires less capital and diversion is limited and not in the scope (Davidson, 2014, 176). Figure 1: installing caisson wall Figure 2: constructing tunnel floor slab Figure 3: Tunnel excavation below the tunnel floor Figure 4: complete tunnel construction end view A typical complete cut-and-cover subway construction used in the section had the following dimensions (see figure 5). ` Figure 5: Typical section: reinforced concrete subway Subway Specification for Traditional Construction within a battered excavation Concrete: 200 mm thick mass concrete raft, design mix C20, cement to BS 12.20 mm aggregate to BS 882. 100 mm thick mass concrete loading coat, to asphalt roof membrane, design mix C20, cement to BS 12, 20 mm aggregate to BS 882. 300 mm thick reinforced concrete floor, walls and roof, design mix C40, cement to BS 12, 20mm aggregate to BS 882. Concrete finishes This design used Steel trowel finish to upper surfaces Formwork The formwork used fair finish to internal and end faces and rough finish to external faces Block work The block work was designed to have 100mm thick, lightweight concrete block walls, laid in gauged mortar (1:1:6) mix as protection to wall asphalt. Waterproofing For the waterproofing, the design was made of a 30 mm thick, three coats, mastic asphalt tanking with angle fillets at all junctions. Then a 100mm wide “Hydrofoil” water bar at all construction joints was used. Surface of concrete to be scrabbled before construction of next section. Ground water is moderate at a level of 98.0m. During the construction phase, temporary works that were used in the process included constructing a temporary diversion from the road to allow for excavation. Alternative method for constructing the subway Contiguous Bored Pile In this design, adjacent piles have Contiguous Bored Pile walls constructed where they have small gaps. This model is used for drilling smaller tunnel. Adjoining Flight Auger (CFA) rigs to drill sequential disconnected piles provide an sparing wall (Chudley, Et al. 2012, 104). Diameter and spatial arrangement of the piles is determined based on soil type, ground water level and order of magnitude of plan pressures. Significant spatial arrangement is avoided as it can lead to undermining of ground via gaps. CFA pile center separation range between 300mm to 1000mm. CFA piles are regarded more economic than diaphragm wall in small to average scale excavations owing to decrease in cost and time of site operations (Chudley, et al. 2011, 103). Besides, no bentonite mud is required for the digging. Contiguous piles are desirable in crowded urban areas, where conventional holding methods would differently encroach the abutting properties, these piles limits ground motions on the backfill face. The pile is made by inittial drilling to the earth using CFA. Cement-sand fix or concrete is then put in under pressure via the auger’s empty stem as it is being drawn back. The Contiguous wall may only be employed where water table is not a hazard or where fixing or jet grouting is employed can be used to cure leakage amongst the piles (Bryan, 2010, 47). Nevertheless, some satisfactory quantity of water can be gathered at the base and removed out. Figure 6:contiguous pile wall (Kyle, and Dimitrios, 2012, 274) The primary weaknesses of contiguous pile walls is that the openings between piles and the leading problems of deficiency of water validation have been efficaciously overpower by interlacing or secant piles (Chudley, Et al. 2012, 107). Conclusions In task 1 of this paper, the ground improvement study involving two study cases can be concluded that, where the waterways are choked in the Olympic park area it is easy to control the clear the water ways. Additionally, it always a good plan to work using the reliable procedures when the ground is contaminated. This way it is easier to clear the ground free of the contamination as well as water choking. Clearing the ground contamination not only provides a clear area, but it improves water filtration to the ground, proper drainage and aeration in the soil. These soil improvement processes create a serene environment that has not bad smells that might emerge from the choked ground. Choked grounds do not have any free flow of air hence it is inhibited by microorganisms that aerobically stay in those areas. For the study case on bearing capacity, study investigated how sand layers are affected by geogrids using silty. Based on system of soil classification method, clay soil is CL and sand classification is SP. From these classifications, silt clay carrying capacity is increased when a layer of sand is place on top of the upper section. Therefore, it can be concluded that, using geogrid can greatly help in improving bearing capacity for silty clay soil. This study can thus, be useful when designing on the improvement of pavement design where similar soil types are available to improve on design strength. In task 2, the subway design compares two construction methods and analyses them in terms of cost and reliability. On the cut-and-cover design, the subway construction is relatively cost friends and more reliable. However, this design maybe faced by challenges to create diversion from the existing road. On the other hand, Contiguous pile wall subway construction method is relatively expensive and may result to a design that has access issues for the passengers. Therefore, it is concluded that, cut-and-cover is the easier method to use in such areas like Asian Business Park to the west of the University. Additionally, Contiguous pile wall requires a lot of space to set up the boring machine equipment, which in this area might be a problem. Further, it can be concluded that, due to some factors related to soil this area deep boring would prove to be more demanding since the tunnel must be drilled without interfering with the existing road condition. References Ashcroft, R (2001) Construction for Interior Designer, London: Longman. Ashworth, A, (2007) Willis’s Practice and Procedure for the Quantity Surveyor, 12th Edition, Oxford: Blackwell Publishing Bryan, T., (2010) Construction Technology – Analysis &Choice, 2nd Edition, Oxford: Wiley- Blackwell Chudley, R, et al. (2011) Construction Technology. 5th Edition, London: Pearson. Chudley, R., Et al. (2012) Advanced Construction, London: Pearson. Davidson, G., (2014) North American Tunneling 2014 Proceedings, New York: SME. I.C.E., (2003) Civil Engineering Conditions of Contract. 7th Ed., London: Thomas Telford. Kyle, R. and Dimitrios, Z., (2012) Geotechnical Engineering State of the Art and Practice: Keynote Lectures from GeoCongress 2012, Virginia: ASCE Publications. Read More