Borrow Pits In Construction Of Road Networks Engineering Essay

Borrow strike offs In Construction Of track Networks Engineering EssayOver the last two decade in that respect has been an unprecedented boom in the Irish construction industry in street infrastructure. It has become a public sight on Irish lanes to sop up countless Lorries carrying satisfyings to these sites ranging from crushed stone, sand, gravel and tarmac. At get these existents argon formed from principal(a) aggregates. The engage of these primary textiles reduces the natural resources of alive quarries. An alternative to this, is the delectation of accept orchestra gibes which leave alone help in the supplying of unanimouss requirements both in general rent and aggregates which may help to head off the use of reserves from dedicateed quarries which get extinct help subjoin the life sentence of these quarries. As with the supply of squ ar, borrow nether regions could alikewise be used for cycle targets likewise because closely jobs woul d moderate inert sensibles that would have to be put away of site to landfill.The term borrow hell is gener in all(a)y utilized by the Contractor when a scheme requires a larger sum total of fill stuff and nonsense versus amount of usable satisfying obtained from cut shares. Borrow pits argon typically located next to the construction site, and in the ideal internet site atomic number 18 soon hind endfilled with suck corporals, such as soft clay, that frequently have to be removed from the construction body politic hence the clobber excavated is borrowed. Normally, large quantities of material, generally bulk fill, be required over a short time.The indite first became involved in the construction of high channel infrastructure during the construction of the N18 N19 Ballycasey to Dromland Dual Carriageway in previous(predicate) 2000 where there was a lot of import material brought into to the job from nearby quarries and materials that had to go to landfill.Fr om the precedents sign interrogation and work experience on various road jobs it was app arent(a) that the use of borrow pits to put forward an alternative source of material would be a worthy dissertation topic and that the knowledge gained would be priceless for future use.HypothesisThe key question that this dissertation bequeath hail isCould the use of Borrow pits in the construction of the road network be a benefitAimTo hold if Borrow pits hindquarters provide the necessary quality material required for the construction of roads and in like manner provide alternative options for the disposal of inert bluster produced on sites early(a) than to landfill.Outline of chaptersThis dissertation is structured into and comprises of six chapters, which are briefly describe as follows. Chapter 1 introduces the reader to the dissertation. Its shows the particular reasons why this topic was chosen. This chapter also let onlines the aim, objectives and hypothesis of the dissert ation. In chapter 2, the methodo enteries used to research the topic are discussed. It provides a review of both the primary and the secondary sources utilized for gathering bring and the limitations encountered in carrying break through the research are also discussed. In chapter 3 stunnedlines the work that is required to as certain(a) if borrow pits are up to providing the material necessary for the construction of roads. It also regards at site investigating and landed estate mental runninging.Chapter 2 Research Methodology universeThis chapter come forthlines the methods of research which were adopted in relation to the fieldwork research for this dissertation. It explains in occurrence the various methods of data allurement that were used, indicating the methods of primary and secondary data collection methods and any(prenominal) limitations encountered during the research are highlighted.Research ProcessThe proposal for my dissertation began to materialise when l ooking back on my previous working experiences in the construction industry. One of the primary(prenominal) bailiwicks of the authors work was involved in road construction. During the initial research the author investigated on the availability of breeding for his topic and when satisfied, proceeded to expand on this proposal. at that place was a medium volume of primary and secondary data operational for this topic and also from the authors work experience there was a quickly open source of primary data.Sources of InformationPrimary SourcesNaoum (2007, p20) states that Primary books is the close accurate source of culture as it publishes original researchThe author sourced valuable primary teaching from Conferences, Reports, Government Publications, (for example NRA) and information from his work experiences.SecondaryNaoum (2007, p20) states that Secondary lit sources are those that cite from primary sources such as textbooks and newspaper articlesThe subject of recycli ng and ache precaution in the construction is very topical at the present and the author was able to gather a substantial amount of information through and through secondary sources. The internet played a vital part in the collection of information. Through this median the majority of information was researched.As hale as the internet other sources of secondary information was gathered fromPublications/Reports mete out Journal and magazinesTextbooksThe text books on the subject where sourced through the LIT and GMIT libraries. literary works ReviewOnce the literature search was completed a literature review was carried out to choose which material was nearly relevant to the dissertation. totally this literature was situated in a literature file. Much of the material which was web ground was stored on a computer file and was not printed out.Research LimitationsThe author found that he was unfortunately limited as there were not a lot of books published on certain past of the c hosen topic. This meant a lot more time was pass searching the internet for information required for the various chapters.Borrow Pit SelectionIntroduction in that location a number of factor in in the selection of a authorisation borrow pits Pantouvakis et al said the boilersuit objective in selecting a borrow pit is to determine the most economical and technically efficient location with the minimal impact.the next body litigate is to establish which are the best sites to develop. The main turns that have to be measure outd allowTechnical ConsiderationsEconomic ConsiderationsSocial and environmental ConsiderationsA summary of all the main factors to be interpreted into account is presented in under put up 4.1. This realise illustrates the large number of probable influences and their interrelationship. The decision to develop one material source rather than an alternative will lots require technology science science judgement in order to adequately balance the techni cal, economic, social and environmental considerations.This Section provides guidelines for carrying out an evaluation of technical considerations and presents an introduction to economic influences. minute consideration of economic influences associated with developing a material supply strategy for sections of road are reviewed in Section 9. The detailed review of capableness social and environmental impacts associated with material resource development is also presented separately, in Section 11.Borrow Pit situation InvestigationIntroduction turn up investigatings are primarily carried out in order to establish trusty estimates of the quantities, quality and extremitying needs of potential road descriptoring materials. Quigley For road projects, a principal aim of the site investigation is to classify the suitability of the kingdoms in accordance with Table 6 / 1 from Series 600 of the NRA stipulation for Road Works (SRW), March 2000 see appendix AThe object of the site investigation must consider the following factorsHow much material is required? The investigation should concentrate on identifying sufficient workable material to supply expected requirements.The method of site investigation will credibly be influenced by the availability of suitable resources (plant and running play equipment).The hardness of the deposits may dictate the method of investigation.The information and nature of burden deposits may influence choice of investigation methods (this can be seen later on in the chapter).Borrow pit prove investigations should be carried out at repair intervals across the site. It is recommended that the information of overburden, and the characteristics and thickness of the workable deposit is investigated on the al-Qaida of a 30 m to 50 m square power grid. This outdistance should only be widened if the site is very large and the materials very interchangeable at to each one ladder location. Unexpected changes in the ground pen should be examined topical anestheticly by making additional intermediate investigation sites in the grid.A site plan of each borrow pit to be investigated should be prepared, showingThe main features of the site.The means of access and the pit location with respect to haul road placement for extr effect.The location of each site been investigated and investigation borehole should be logged using modern GPS or mistakable devices. This information will be important when you go to work out the quantity of the resources in each potential site been looked at. This process will be looked at further on in this chapter.Desk top tryA desk top study is one of the first steps under taken when you look at a potential site because it can provide you information already available about a site. (Simons et al, 2002). Within the construction industry, desk studies are well know hardly are an under-used method of gathering and assessing active information about a site. Desk studies generally in clude a opthalmic inspection of the site and its surrounding area ( ordinarily called a walkover accompany).The desk study examines and d desolates together quick information from a variety of sources to form an initial appraisal of possible ground conditions. A good starting portend is to use OS maps. These allow the site to pin pointed and an accurate grid reference to be obtained. This permits much more accurate references on the geological maps used later, which can be got from the Geological Survey of Ireland, which show existing geological records for the area and also historical maps could be a help. The walk-over survey of a site can throw valuable insight into potential ground condition problems (for example slope instability or modify ground weewee) and contamination issues (revealed for example by vegetation dieback). On site visit, local resident can often provide information on groundwater and sources of raw material in the area. The combination of the desk stud y and the walk-over survey is an extremely woo effective first stage in an investigation. It provides early warning of potential problems and a sound basis for the scope of subsequent, more detail investigation which may follow. The desk study and walk-over survey can also provide early recognition of site issues such as ecology and archaeology which may have implications on site selection.Traditional Ground investigation methodsThere are number of different types of ground investigation methods available on the market and we will look at few of the most common method used. essay Pits.Boreholes investigation, slatternly Percussion Boreholes. merry-go-round Drill holes.geophysicalSeismic Refraction Method.Electrical electric resistance MethodTrial PitsTrial pits are predominantly carried out using mechanical excavators which will give information of the ground while the cut into is taking place. Throughout the process photos are taken of the ground conditions and samples of mater ial Quigley (typically 30kg for engineering performance tests) are also taken are specified ground depths. Depending on the excavators stumble this will determine depth or if fundamentals is reached, Cat 320D digging depth is up to 6.690m (Caterpillar 320D brochures). All field work is carried out in accordance with BS5930.1999. finger Picture of Trial Pit operation.(Source www.prioritygeotchnical.ie) rule Pictures of samples taken(Sourced www.prioritygeotchnical.ie)(Quigley) points out that A suitably experienced geotechnical engineer or engineering geologist should supervise the trial pitting works and convalescence of samples. It is important that all trial pits are backfilled subsequently testing is completed. happen appendix 2 for example of Trial Pit log.Borehole InvestigationLight Percussion Boreholes (Shell and wimble)Light percussion boreholes or otherwise known as Shell and Auger boring can be used in all types of res publicas and is mainly used for depths exceedi ng that of an excavator.The rig consists of an engine powered winch and tripod frame that is easily collapsed for towing behind a four wheel drive vehicle. The boreholes are usually 150 to 200 mm in diameter and trade name casing is typically required throughout most of the hole. Boreholes of 20 to 30m depth are commonly bored in suitable soils, however in mixed soil, depths can vary samples should be taken at ( Quigley) 1.00m intervals or change of strata. See gens 3 for example of rig in working position.Figure Light percussion boreholes rig(Sourced www.southerntesting.co.uk)Boring is achieved by repeatedly dropping an auger, consisting of a steel tube, to the bottom of the borehole. In sand and gravels a valve is fitted to the lower end of the tube to trap the material submission it, this is a shell or sand auger. Any large stones or small boulders encountered can be broken up with a rotund chiselling tool. Large sickish samples may be obtained, but below the water table th e washing action of the shell may remove near of the fine material from sand and gravel deposits.Attachments to the rig allow the use of light circuit drilling equipment that will enable limited investigation of the characteristics of any bedrock encountered. See figure 4.Figure Attachments for light rotary drilling(Sourced Clayton et al,, 1996)Rotary Drill BoreholesRotary drill rigs come in a variety of sur instances from small skid mounted machines to large hand truck mounted machines. See Figure 5. They use a rotary action combined with downward force to grind away the material in which the hole is made. The primary use of rotary drilling techniques is to investigate rock quality by taking core samples. However, rotary drilling rigs can be used for non core drilling. A destructive tricone (rock roller) drill musical composition is generally used to earn a non-coring hole. Only the rate of advance and characteristics of the cuttings flushed to the surface by the drilling wate r give any indication of the strata penetrated. This can be supplement by small disturbed samples recovered from a driven sampler (i.e. SPT sampler). Non core drilling is wherefore of limited use, but might be employed through the overburden covering a rippable rock or quarry stone.Figure Rotary drill rig in operation(Sourced www.prioritygeotchnical.ie)Rotary coring involves the use of a water lubricated diamond or tungsten tipped mindless core bit attached to a core sample recovery barrel and a series of hollow drill rods. See figure 6. In weak or fractured rocks better quality core are recovered from larger diameter bits. Some ground investigation drillers have developed a technique for recovering disturbed soil samples by dry drilling with a single tube core barrel, butThis practice is not widely used and is less successful in coarse deposits with little credit card clay binder. Example of rotary log see appendix 3.Further information on site investigation drilling and the des cription of drill cores is contained in BS 5930 Code of dissemble out for Site Investigations (1999).Figure Layout of a small Rotary core unit.(Sourced Clayton et al,, 1996)geophysical ExplorationThis method of investigation is not commonly used as it is not suitable for all ground conditions and there are limitations to the information obtained. The main use of this form of exploration is it can give bedrock and water table levels and it can also detect sub-surface cavities. The two main methods are.Seismic RefractionThis method involves the generation of an artificial shock waves in the rock or soil and then records the finding in a series of detecting station which are place across the area been investigated. The detecting stations are known as geophones. This method is often used to detect buried channels and identify bedrock levels. See figureFigure Seismic Refraction Method(Source www.geophysics.co.uk)Electrical Resistivity MethodThis method involves the driving of four equa lly spaced electrodes into the ground in a straight line. When this process is done and a underway is passed through the outer electrodes and the contrast in volts with the inner electrodes is measured. See Figure 8Figure Electrical Resistivity Method(Source www.discoverypro gmme.ie)Soils examenThe suggest of the soil testing of material from the borrow pits is toDetermine the engineering properties of the material.To establish if the material is the same quality throughout.To provide document records of the pit for the lymph glands.In order to fully assess the engineering properties of a borrow pit material it is necessary to have samples tested in a veridicals Laboratory. The purpose of testing material is to see if the comply with the specifications of there indented use. The laboratory will use standard testing procedures to classify the samples taken. In Ireland the parameters set out in Table 6 / 1 of the NRA SRW include a combination of the following.Typical tests under taken are for soils and aggregatesMoisture content10% finesParticle size gradingPlastic Limit and luculent LimitCBRMCVTriaxial trim Strength Test(Laois County Council 2007)Moisture contentMoisture content is the amount of water to amount of dry soil. The method is based on removing soil wet by oven-drying a soil sample until the weight rest constant. The moisture content (%) is exercised from the sample weight before and after drying tests carried out to B.S.1377 Part 2 1990 for soils and BS 812 Part 1091990 for aggregatesFigure Soils Oven(Sourced examen equipment Supply)10% FinesThis test is not too dissimilar from the test to determine the aggregate crushing value which determines the ability of an aggregate to resist crushing. merely instead of using a standard force of 400kn. the force at which 10% of fines are produced is noted as the Ten Percent Fines Value. This usually requires a number of tests and a graph to establish the ingest figure. This test tends to be used fo r softer aggregate where a force of 400kn. would crush most or all of the aggregate. This test is carried out BS 812 Part 111 1990 for aggregates partly Grading TestsThe particle size distribution grading of a road surfacing material is an essential guide to the suitability of the material since the engineering properties are very dependant on grading. See Figure 7. Testing is carried out to B.S.1377 Part 2 1990 for soils and BS 812 Part 103.11985 for aggregates.Figure block out Test(Sourced Soil Compaction Handbook)Plastic Limit Testing and Liquid Limit TestingThe Plastic Limit (PL) is an indication of the fortune moisture content at which the soil fines change from a semi solid to a fictile state. In this test a 20 gram sample of material passing the O.425 mm sieve is mixed with a little water until it becomes plastic enough to be formed into a ball. The soil is then moulded between the fingers until the surface begins to crack. It is then repeatedly turn on a glass plate into 3mm diameter threads until longitudinal cracking causes the tread to start to break up. This moisture content is the plastic limit.Test are carried out to BS 1377 Part 21990, CL5Figure Plastic limit test and equipment(Sourced http//ral.train.army.mil) and (Sourced www.humbolgtmfg.com)The Liquid Limit (LL) is an indication of the percentage moisture content at which soil changes from a firm plastic state to a soft liquid state. Two methods are available for determining the liquid limit the traditional method using the Casagrande utensil and the more recently developed cone penetrometer method.Test are carried out to BS 1377 Part 21990, CL4.3 4.4Figure Casagrande equipment Figure Cone Penetrometer(Sources www.humbolgtmfg.com) (Sources www.sbe.napier.ac.uk)The difference between the Liquid Limit and the Plastic Limit is called the Plasticity magnate (PI). This index provides a good guide to the cohesive properties of a road building aggregate. A high PI may indicate the strawman o f an undesirable amount or type of clay.CBR testIt is in essence a simple penetration test developed to evaluate the strength of road subgrades. How strong is the ground upon which we are going to build the road. (Summers 2010) Tests are carried out either unsoaked or soaked. Unpaved road materials would unremarkably be tested according to the 4 day soaked test procedure. An estimated CBR value may be derived from the results of grading and plasticity tests. Tests are carried out to B.S.137741990 Section 7Figure CBR test apparatus(Sourced Testing equipment Supply)MCV TestThis test involves compaction of soil or fine aggregates using a hand held device. The compactive effort can be compared to that needed at the optimum moisture content. This enables a comparison with the tangible moisture content of the soil. Test carried out to BS 1377 Part 41990 see Figure 13 for test apparatus.Figure MCV apparatus(Sourced www.ele.com)Triaxial overcharge Strength TestThe triaxial shear strength test subjects a soil specimen to three compressive stresses at right angle to each other with stress being increased until the sample fails in shear. This test is carried out to predict how the material will behave in a larger-scale engineering application. An example would be to predict the stability of the soil on a slope, whether the slope will collapse or whether the soil will buy at the shear stresses of the slope and remain in place. Tests are carried out to BS 1377 Part 61990. See figure 14 for test apparatus.Figure Test apparatus for Triaxial Shear Strength Test(Sourced www.namicon.com) new-fangled Changes to Site Investigation and TestingAt present all Geotechnical investigation and testing is carried out to B.S. but come 31st March 2010 all test will be carried out using the new Eurocode 7 this will be for all publicly funded project. This does not ease up to the private celestial sphere but there are likely to follow suit. Example of changes.TC 341 Geotechnical invest igation and testing 14688 Identification and classification of soil 3 move 14689 Identification and classification of rock 2 Parts 17892 Laboratory testing of soil 12 Parts 22282 Geohydraulic testing 6 Parts 22475 sampling methods and groundwater measurements 3 Parts 22476 Field testing 13 Parts(Sourced New Irish Geotechnical Standards and Selection of Characteristic Parameter Values 2009)Resources estimationIntroductionIn this chapter the author will look at how quantities of materials that can be potentially in a borrow pit and how they may be calculated.One of the main primary objective of a borrow pit investigation and testing is to establish the extent of the different classes of materials and there suitability to the given project. With all the information in the next objective is to calculate the quantity of material that is in the potential borrow pit to see if its a viable option to proceed with. The potential quantity of material that can be extracted from a borrow pit should always be calculated in cubic metres (m3). A cubic metre should be seen as a box of material with a length (l) of 1 metre a height (h) of 1 metre and a depth (d) of 1metre.Before and estimates can be taken off a detail topography survey of the potential borrow pits will have to be taken see figure 21 for typical contour survey. However, with all information from the investigation of the site it can be hard to estimate an exact amount so it is better to estimate on the conservative than on the generous. This may come about if the information between the trial pits may vary from data collected as seen early a grids of 30 to 50 meters should be used and for larger areas if could be up to blow meters gridsThere are different method of calculation the quantity of material that in the given site depending on the borrow pit make up but the most simple way is to break the area up into simple shapes such as rectangular prisms or angulate prisms. The volume of material in these shape s is estimated by first sharp a representative area in square meters (m2), and then multiplying this area by its depth or a length (in metres). It may need to be an average depth or length if the pit is irregular in shape or the deposit has a variable thickness. Formula for calculating the areas for different type of pit can be work out using the standard mathematically formula to get the quantities for the site. See figures 17,18,19,20 trapezoidFigure Formula for a Trapezoid shape intensiveness = pes X HeightFigure Formula for PrismsVolume = Length X Width X HeightFigure Formula for a angularVolume = 1/3 pr2x heightFigure Formula for a cone shape(Sourced Area and surface Formulas)Another method of tier if available to you is different types of computer packages that can do the work for you like AutoCAD 3D civil packages.Figure Typical Contour Survey(Sourced Volume Calculations)Material Wastage, Shrinkage and BulkingMaterial WastageWastage can occur if site investigation reports of material dont add up to what in the ground and material been use for work it was not envisaged to do, like having to create bund not accounted for some.Material BulkingMaterial bulking will also to be taken into account when hauling materials of the bulking-up factor. When materials are excavated they are loosened and sometimes broken down, this result in an increase in volume per unit weight known as bulking. The bulking factor of a material is the bulk density in the pit face (bank) divided by the loose bulk density. A bulking factor of 1.25 indicates that carbon m3 of bank material will become 125 m3 of loose material in the stockpile.Material ShrinkingCompacted material, material that has been excavated from it natural state and placed some place else for compaction. With compaction the volume reduces. The same can apply to shrinkage when material is been compacted what was originally 1m3 in a compacted state with shrinking factor is 0.85m3.Table 1 Typical Material Density , Bulking and Shrinkage Factors.(Source Earthworks)The Resources Estimation has a dual purpose with given you the quantities of resources out but also on the other hand the amount of material which if can be disposal back into to fill the pits from surplus or unsuitable material that cannot be use on site.LegalisationIntroductionThis chapter discusses of both mean jurisprudence and bobble code in the terms of Construction and grading be adrift in the construction sector. The be after canon we will be looking in relation to opening up of a borrow pit for bulk material (soil) and the production of aggregates. In CD squander legislation for the disposal of inert material. In the area of waste solicitude there has been a number of direct and indirect (both interior(a) and EU) legislative influences on how operations should be carried out with the regards to CD waste in road constructionThe Planning and maturement turning 2000 and associated Regulations 2001The Planning and Development Act 2000 is the main act for planning permission in Ireland and this process is overseen by the different Local Authorities in the country. Regulations 2001 is the statutory legislation that applies to new and existing extractive developments and ancillary facilities in Ireland.Quarries (including sand and gravel pits) direct before the existence of planning legislation in Ireland that was implemented in 1964 did not have to obtain planning permission and were essentially unregulated. scorn this, much self-regulation took place such as imposition of emissions (noise, blasting, and dust) limits and the implementation of Environmental Management systems accredited to IS0 14001.However, under Section 261 of the Planning and Development Act 2000, a new system of once-off registration for all quarries was introduced. Only those quarries for which planning permission was granted in the five years before section 261 (i.e. after April 1999) became operative are excluded. Secti on 261 has also resulted in some extractive sites being required to submit an Environmental impact statement and to go through the formal planning process. This review process has resulted in street smart environmental and biodiversity management conditions being enforceable on all charge sites this process is largely complete at this time.CD Waste legislationAs spoken earlier on CD waste legislation in Ireland is influenced by European waste policy and legislation. The EU waste management is based on the waste hierarchy which gives preference to waste prevention, then to waste recovery (including reuse, recycle and energy recovery). And finally to waste disposal (to landfill) See figure 22 for hierarchyFigure Waste hierarchy(Source Fas CIF Handbook on Construction Demolishing and Waste)European polityThe majority of European waste management directives are based on the Symonds report 1999 which evaluated the recycling of CD Waste in each of the atom state and prepared 55 recomm endation.The following is a list of the most important recommendations of the reportFly tipping subject to sanctionsLand filling of CD waste should be discouraged by member states.CD Waste derived aggregates should not be discrimination in the market place, primary aggregates and CD Waste derived aggregates should be both be considered as raw materialsThe client should demand that Environmental Impact Analysis be undertaken for each project which could form part of Environmental Management Plan.Governments to draw up content Waste Management plans for CC waste.The main based EU based legislation that influences CD waste management on a national level areFramework Directive on waste 75/442/EEC plus amendmentsFramework Directive on Hazardous Waste,1991 91/689/EEC