A buildingconsists of two major parts a sub structure and a super structure. Sub-structure is the core of any building. It is thelower part of the specified building which would usually be found beneathground. Its main purpose is to receive and support the load from the main partof the building (the superstructure), and transfer them down to the layer ofground beneath it which can bear the entire load. The main section of thesub-structure is the foundation, which is what bears the load and transfers itto the ground.
Therefore, measuring the soil for the correct foundation is veryimportant as in the situation of wrong measurement andcalcs this will result in the foundation ultimately failing its purpose as itisn’t able to handle the loadSuper-structure is the main region of the buildingwhich sits on the foundation, the substructure above ground level. It consistsof columns, walls, flooring, roofing and beams. The purpose will be defined bythe client.
The measurements for the main building directly affect thefoundation.As mentionedabove, it is very important to have the correct measurements for the soil toconstruct the correct foundation. This is also important because it has animpact on the method used to create the foundation, as well as other factorssuch as project budget which in turn affects the materials used, thecontractors hired to construct and consultants hired to supervise and guidealong the project’s lifetime. Moreover, gathering the correct soil measurementsallows the client’s project team to identify the best way to ensure groundstability, temporarily during the construction process, and permanently, forthe buildings lifetime.Many methods canbe used. In the modern era Our time sees much more efficient planning thanbefore when it comes to determining the best method to use to createsub-structures.
The most common technique used nowadays is piling systems. The reason why it is called piling systems isbecause there are different piling techniques that can be used to construct asubstructure and I will highlight the two different piling techniques and someof their types.Drivenpiles, also known asdisplacement piles, are a commonly-used form of building foundation thatprovide support for structures, transferring their load to layers of soil orrock that have sufficient bearing capacity and suitable settlementcharacteristics. Driven piles are commonly used to support buildings, tanks,towers, walls and bridges, and can be the most cost-effective deep foundationsolution. They can also be used in applications such as embankments, retainingwalls, bulkheads, anchorage structures and cofferdams. The piles are driveninto the using pile drivers, which are of different types diesel hammer,hydraulic hammer, piling rig, vibratory hammer or a drop hammer.
As shown below https://theconstructor.org/geotechnical/pile-driving-equipment-types-uses/17605/ Drivenfoundations are of two types:Pile foundation systems: Pile foundations are deep foundations. They are formed by long, slender,columnar elements typically made from steel or reinforced concrete, orsometimes timber.Pilefoundations are principally used to transfer the loads from superstructures,through weak, compressible strata or water onto stronger, more compact, lesscompressible and stiffer soil or rock at depth, increasing the effective sizeof a foundation and resisting horizontal loads. They are typically used forlarge structures, and in situations where soil is not suitable to preventexcessive settlement. An example is shown below. https://www.onlinecivilforum.
com/site/index.php/2016/09/10/pile-foundation/https://www.designingbuildings.co.uk/wiki/Pile_foundationsMono-pile foundations: The mono-pile structure is a simpledesign where the tower is supported by the mono-pile. This will usuallycontinue all the way down into the seabed.
The pile depth within the seabed canbe adjusted to suit the conditions. Mono-piles are a common use for foundationsin the offshore wind market. Well suited for sites with a water depth of 30mand less. An example is shown below. http://www.4coffshore.com/windfarms/monopiles-support-structures-aid4.
htmlDrilled Piles: Also known as Cassions, they usedrotary boring machinery that drills the pile beneath the ground, commonlydrilling rigs are used. Parallel to driven piles, drilled piles use the samematerials but install them in a different way. The piling technique, however,varies depending on the site geology.
For instance, if the soil was wet, thetechnique would be Wet-Boring and if it was dry, the technique would be Dry-Boring.Drilled piles are of two types:Under Reamed Piles: This type of drilled piling usesmechanically produced large bases which increases the amount of bearing thebase can handle and shift to the underlying soil. These bulb or bell shapedbases can have diameters of up to 6 metres and they are best suited for blackcotton soil as well as expansive soils which have different moisture levels indifferent seasons.Auger Piles: This type of pilling is a goodreflection of how it works as its name suggests; Auger means to drill and thatis how this works.
The auger, drill, has a stem in the middle and it is drilledinto the soil until the required depth. It is then slowly withdrawn from theexcavation taking all of the drilled rocks and soil out and pumping a concretemix via the stem into the excavation. This process is done carefully so thatthe concrete pressure does not cause the soil to crack or deform. Once theconcrete foundation is in place, reinforced concrete is fitted into thethen-wet concrete and it is left to dry. This technique is very good as it canresist large loads and it used to support towers, bridges and other differentbuilding types.Ground StabilisationIt is importantto understand that no site work can start without the area being surveyed.
Thisinitial step is crucial simply due to the fact that the soil (ground) where thebuilding is to be constructed has to be stable enough to carry the building onits surface. Making sure that the ground is stable should be the first thingthat should be focussed on before choosing the type of excavation to be used.Reinforcing the soil not only makes the ground stable to erect the building, italso enables the ground to become pedestrian pavements, roads, railway tracksand also the strengthening of the soil also allows for underpasses and utilityservices to pass under the building.There are twoways of stabilising the soil; the first is by disposing the material found onthe site and importing stronger materials.
The second is by stabilising theexisting site soil with binders, which are materials which strengthen or holdmaterials together such as lime and cement. The first method is rarely used in today’s day and age is at costs a lotof time and money plus it is not as effective as the second method, which isfaster, cheaper and heavily used.A land fillingheavy machine is brought on site and it digs up the soil where the foundationsare to be placed. The soil is then mixed with a cement-lime mixture and thesoil is levelled out. It is left to dry and after it is checked for itsstrength using stabilisation calculation methods; if the soil has become animpermeable site work commences, if it hasn’t, it is further strengthened to asatisfactory level. The advantages of using this method are:Itsaves money by mixing binding materials in-situ instead of prefabricatingmaterials and importing them to the siteItsaves time since less transportation of materials will be required and the soilwill stabilise over a shorter period of timeItis greener since less earthmoving equipment will be involved since there willno heavy and continuous transport of strengthened materials to the site andremoval of unwanted materials from the siteItsaves waste due to the fact the already-existing material is used andstrengthened instead of dumping all of it from the site and importingmanufactured materials. 2.2The main reasonof preparing any budget is to be cost effective by controlling unneeded costs.
A budget plan must be created with team or consultants to aid him/her on thismatter. However, the consultant must bear in mind that the client is seeking tolower and tighten the budget to save costs. Constructionprojects are assigned with a budget for hiring the contractors, purchasing thematerials and for emergencies and with a time-scale by which the project has tobe completed. In this project, there hasn’t been an assigned budget andtime-scale however the process has to be quick but also one which makes surethat the building is made of a high quality and safe. In order to achieve this,aspects of the project must be considered. this include materials which are tobe used as the foundations, services, site access, the type of excavation to beused, and etc.
However, the focus is the actual construction and specificallythe sub-structure, foundation, as it is the beginning on which thesuper-structure will be founded.The basement willmost likely be constructed in an area that won’t require the strengthening ofthe soil before excavating. This means that there will no extra costs for suchservices. The excavation can begin straight away as there will be no waitingfor the soil to dry up after strengthening it. Another thing to bear in mind is,given the fact that the construction site is most likely on a residentialstreet. There is a high likeliness of existing utility services that have to beconsidered. The fear would be that the existing utility tunnels would have tobe diverted, or avoided before the construction can commence hence adding tothe cost and duration of the project.
In terms ofexcavations, one of the most common types of excavating is piling, it proves tobe cheaper but not as time-saving as the diaphragm wall. The diaphragm walltechnique costs more as it uses more concrete than the piling method would usebut uses less machinery so the price difference somewhat levels out. Thediaphragm wall technique controls ground stability and groundwater levels moreeffectively than piling as it produces a strong layer above the soil. Also,diaphragm walls use tubes that are temporary structures and are reusable,recyclable and they can be easily removed to be replaced with the concrete forthe main structure. It works by excavating the soil into trenches, pumpingslurry into the trench to support the soil and make it water resistant, placingthe walls at fixed intervals, pouring concrete into the gaps between the walls,reinforcing the concrete with steel frame and then removing the slurry from thewalls. The picture below shows the excavation process of the diaphragm walls. http://www.bauerlebanon.
com/shared/images/bst/verfahren/Schema_SW-Herstellung_gegreifert.jpg This basement willobviously be below the super-structure, the top-down construction techniqueshould be used. The top-down construction method allows for the construction ofa basement using the same foundations the super-structure uses and this is verycost effective and time-saving as the permanent retaining diaphragm wallbecomes the walls of the basement and its ceiling.
How the top-downconstruction level works is by excavating the soil to build the ground floor ofthe super-structure while leaving a shallow excavated gap in the middle toallow the basement to be erected. Once the ground floor is built, through theshallow excavated gap, reinforcement materials slabs and beams are lowered andare installed into their locations. After this step, another excavation trenchis dug beneath the shallow gap and the reinforcement concrete is installed.Once all the lower levels have been constructed, the parking spots and pavingare set out. http://www.
ethioconstruction.net/?q=information/top-down-construction-methodUnderground TunnelsRegarding theconstruction of the basement, we could use existing underground. For example,if the construction location is most likely in London, the existing LondonUnderground Tunnels will have to be considered as well all the existing utilityservice tunnels but if the construction location is within the cross country,the main and only concern would be the existing utility service tunnels asthere is no underground rail or surface transport. It is important to note thatutility pipes are not always tunnelled but are sometimes protected with extralayers of soil and water penetration-preventing materials. With this in mind,in the chosen location, there are existing underground tunnels and what needsto considered is the significant vibration the excavation process will causewhich could potentially damage the tunnels causing their collapse and a stop tothe service that was being provided. By identifying the existing services, theexcavators can use mitigating techniques such as pre-boring driven holes whichis a method which uses less impact energy when driving foundations into theground or using a completely different foundation design.
Since I havesuggested that the Diaphragm method should be used this is in itself a completealternative to affecting the existing tunnels. They should be installed adecent amount away from any existing tunnels to avoid damaging nearby buildings.If the Diaphragm method which involves digging the soil using an excavator tothe desired depth, then filling the excavation with slurry to make it waterimpermeable, then filling the excavation with concrete and loweringpre-fabricated steel into the concrete for reinforcement. 2.
3 DrainageDrainage is thenatural or artificial channelling of water away from one place to another,usually the central sewage network. In this railway project, water will be usedduring the construction process to remove dust, produce cement etc. This allmeans that removal of water from the site is needed and this can only be doneby the correct construction of drain pipes and the diagram below shows anoverview of the construction method. (Upland Pathwork, 2015) To construct thedrainage pipe, the operatives should excavate a trench that is wide and longenough to fit the pipe and should be deep enough to be able to close it off asshown. Following this, the pipe should be assembled to the required length, andit should be careful positioned by a crane into the excavation.
This should beaccompanied with constructing the walls to protect the pipe by placing thebedding for the pipe at its base and its sides. Aggregate should then be pouredover and around the pipe so that it is covered by it and this acts as a water impermeablemembrane and a protection layer for the pipe and finally connect the building’sdrainage to the surrounding sewers and restore the backfill from the excavatedtrench to cover up the drain pipe.CulvertsCulverts arestructures that allow the flow of water underneath a road, bridge, railway orany similar construction and are usually designed from concrete, plastic orsteel. They can be shaped in different ways circularovalboxarchedDepending on thearea it will placed and the load it will carry. This project will see the useof a lot of water during construction and so to allow the water to flow towardsthe drainage pipes, culverts will be used to access the site to prevent heavymachinery and operatives from coming into contact with construction-producedand to prevent any site flooding.
org%2Fconstruction%2Fconstruction-of-culverts-minor-bridges-siting%2F16963%2F&psig=AOvVaw06Kzw8FYGc9B4jlvwsf1L7&ust=1516750117644631To construct theculvert as shown above, the soil will be excavated using an excavator and atruck will remove the excavated soil from the site. Gravel will then be linedin the excavation to act as bedding for the culvert pipe and its surroundingwalls. The precast concrete pipes will then be fitted into the excavation ontop of the gravel with the help of a crane and will then be treated with awaterproof membrane, to make it resistant.
Following this, more gravel will beused to cover the culvert and the excavated material will then be backfilled ontop of the culvert and the access road to the site will be placed. The inletsection is the side of culvert that leads to the construction site and it iswhere the water flows down towards the outlet which is where the drainage pipestake the water away from the construction site.Culverts lead to changes in community compositionover the length of the culvert because of the abrupt changes in light conditionsand stream bed. Culverts can either impede or facilitate upstream movement. Thebarrier effect of culverts does not have an effect on communities either sideof culverts.https://www.sheffield.
ac.uk/doncatchment/work/projects/culvertsUnderpassesAn underpass, ora subway, is a path beneath roads or railways which allows cyclists andpedestrian to walk across safely without the risk of coming into contact withroad or rail traffic, having underpasses help moving from one site area toanother safely.To construct asubway, precast reinforced concrete sections should be used.
An excavationshould be dug deep enough, and filled with aggregate to prevent water flow intothe concrete walls and damage them. Theconcrete panels will be precast into a U-shape and will be held together bybinding materials as well as bolts and nuts in their metal parts. The concreteU-shape subway is then lowered into the excavation with the help of a crane andits surroundings are strengthened with concrete. Once this has taken place,sheet piles are drilled besides the U-shape subway to build the roads on top ofthe subway which are then held in place by reinforced concrete columns placedat regular intervals. Finally, retaining walls are installed beside the subwayto prevent soil collapse and destroy the subway.