Importance Of Site Investigation And Retaining Walls Construction Essay Example For Students

Importance Of Site Investigation And Retaining Walls Construction Essay As a Construction Management Consultant of I-Consult Ltd appointed by I- Build Sdn Bhd, I am required to suggest different types of retaining wall system available. My proposal focuses on the site probe, importance of retaining wall, building methods, design constructs and preventative steps to extenuate functional failures. I am required to suggest an appropriate choice of the most suited retaining wall system used to the Board of Directors, in which the undertaking is located at hilly country which consists of 20 units of luxury cottages. In this proposal, I am traveling to discourse: the importance of site probe, the importance of retaining wall, the construct of retaining wall, types of retaining wall the most suited retaining wall for this hilly undertaking. Outline1 The Importance of Site probe2 Failure of Site Investigation3 What is Retaining Wall?4 The Concept of Retaining Wall5 DESIGN PRINCIPLES6 Earth PRESSURES7 Stability8 Consequence OF WATER9 SLIP CIRCLE FAILURE10 The Importance of a Retaining Wall11 Retaining Walls Hold Back the Earth12 Retaining Walls Provide More Useable Land13 Retaining Walls Avoid the Ground from Washing Away14 Types of Wall15 Mass retaining walls16 Cantilever walls17 Counterfort Retaining Walls18 Reinforced masonry retaining walls19 Decision The Importance of Site probe Every semisynthetic civil technology construction is found on, in or with land. The construction we put on the land is semisynthetic. We can command to plan every point that goes into our construction, such as concrete, support, bricks and even the last wall stopper. However, the land below on which this construction will stand is non semisynthetic. We normally have less cognition about it and we doubtless can non plan or command its behaviour. The land below will find the economic systems of how tall, how heavy, how safe the concluding construction is traveling to be and non the other manner unit of ammunition. In short, the safety and economic sciences of every civil technology construction is influenced by the belongingss of the land on which this construction will stand. These belongingss of the land below or sub-soil belongingss are obtained via Site Investigation. In any site probe work, the inquiries which should be resolved in finding the probe plan are: What type of probe is needed, Why they are needed, Where the existent field plants should be performed, How the work is to be done. Whether the probe is sufficient or excessively much. Site probe is usually important and carried out prior to the beginning of design of a building undertaking. Site probe has been defined as probe of the physical features of the site and includes documental surveies, site studies and land probe. It is besides refers to the existent surface or subsurface probe, including on site and research lab trials. In wide sense, survey of the site history and environment, reading and analyses of all available informations, and doing recommendations on the favorable/unfavorable locations, economic and safe design, and anticipation of possible hazards should besides be included in site probes. First and first, a desk survey to uncover informations which may already be refering the site, its geology and history, together with a site reconnaissance, is priceless and can be done before purchase at minimum cost. This may be followed by test roughness, examining or tiring as appropriate to the conditions revealed by predating surveies and in the visible radiation of the development proposals. It is besides a safeguard to minimise harm that could be caused by these dirts could besides be communicated at this phase. At least place inhabitants would be alerted to possible jobs ( and the associated costs ) from the beginning, therefore enabling them to do informed determinations sing the most appropriate foundation system for their places. Site probe is designed to place the features of dirts or fill stuffs which lie beneath the site, the groundwater conditions and the being and extent of other physical characteristics or contaminations which may be present. This information influences the choice and design of an appropriate structural signifier for the proposed edifice. It is a procedure which should go on on an iterative footing throughout the design and building stages. Post-construction monitoring can besides be of importance in many cases as portion of a proof procedure. The combined edifice tonss indicated in figure 1 must be safely supported by the undersoil and besides guarantee that unreasonable motions of the edifice do non happen. If the back uping dirt is sufficient resistant and its features under burden are likely to stay satisfactory, the jobs of support and motion will be easy resolved. However, few soils other than stone can defy these concentrated tonss and it is normally necessary to roll up the single-minded tonss at their lowest point and reassign them to adequate bearing dirt known to be available on a peculiar site ( figure 2 ) . Figure 1: Combined edifice tonss Figure 2: Method of reassigning combined edifice tonss to back uping dirt. The general distribution of dirt types in the United Kingdom is indicated in figure 3 ; the dirts include peat, clay, slit, sand and crushed rock. Matching safe bearing force per unit areas are besides given. Figure 3: simplified distribution of assorted types of back uping dirts Last, site probe should be undertaken by professional specializers, such as surveyors, geotechnical applied scientist and land probe contractor, and in a phased mode. The land probe contractor is responsible for supplying dependable factual information. The geotechnical adviser should responsible for the planning A ; executing of the probe plan, reading and analyses of consequences, and doing appropriate design recommendations to avoid over design every bit good as insecure design. Failure of Site Investigation Due to miss of or insufficiency of guide/code demand sing the extent every bit good as quality of site probe work, geotechnical failures frequently occurred. These failures sometime led to catastrophic catastrophe and imposed serious menace to public safety. For the Highland Incident in Kuala Lumpur in 1993, the Architect appointed qualified civil applied scientist to be the confer withing applied scientist for Highland Towers. Initially, civil applied scientist s range of plants was restricted to the structural facet of the three blocks. But later, the civil applied scientist was engaged by the developer to subject proposals over the drainage of the country. His drainage program was approved. He was besides retained by the developer to plan and oversee the building of two retaining walls on the Highland Towers site. The Plaintiffs claimed that the civil applied scientist was negligent for the undermentioned grounds: ( I ) Planing unsuitable foundations ; ( two ) Lack of attention and concern of the hill and incline ; ( three ) Publishing a notice to the governments corroborating the drainage plant was completed when merely a fraction of it was done. By the above Acts of the Apostless of preparing, planing and oversing the building of Highland Towers and the drainage system of the Highland Towers site, he was negligent and had caused nuisance to them. The civil applied scientist had used rail hemorrhoids welded together as foundation to back up the three flat blocks. This type of hemorrhoids, which was considered inferior to concrete hemorrhoids, was accepted in the technology and edifice industry to back up high-rise edifices at the material clip. Therefore, no mistake can be attributed to the civil applied scientist in utilizing the rail hemorrhoids as he was merely adhering to the recognized professional pattern at that clip. However, there was deficiency of consideration by the civil applied scientist to the hill and the incline straight behind the three blocks. The tribunal ruled that the civil applied scientist should hold moderately anticipate the danger of a landslide bring forthing a sidelong burden against the foundatio n of the edifice. For this, he should hold exercised attention to either design or concept a foundation to suit the sidelong burden or guarantee that the incline was moderately stable. Failure to make so is a breach of his responsibility of attention he owes to the Plaintiffs since his responsibility was to guarantee the safety of the edifices he designed and built. The civil applied scientist s effort to deny liability on the land that he relied on the developer to guarantee that other retaining walls were constructed decently was unsuccessful. The justice found that it was incumbent upon the civil applied scientist to ask and determine whether the work was that of a qualified professional and what its impact might be on the safety of his ain edifice. Symbolism of the Scarlet Letter EssayThe soil which remains has to dispatch when the side of a hill is dug out. If left entirely, it will finally comes toppling down. The soil will be held back and the safety will be ensured. Retaining Walls Provide More Useable Land A walk-out cellar, terrace, resort area, garden, tennis tribunal or swimming pool might be installed into proposed development. If the land is turn overing or hilly, work can non be begun until the land is leveled off. A kind of drop, where a portion of the proposed land which is non dug out is higher than the lower level land, will so be left out. Adding a retaining wall will hold more useable land every bit good as will add construction and beauty to your new country. Retaining wall can be used as stairss into the pool where pool equipments to be held. Retaining Walls Avoid the Ground from Washing Away If the country gets a batch of rainfall or close H2O such as lake, a retaining wall will maintain the H2O from gnawing the dirt of your landscape gardening and around your foundation. This could be a safety step to forestall landslides and river of soil from drifting towards the edifices. Types of Wall Mass retaining walls Mass retaining walls besides known as gravitation walls. They rely upon their ain mass together with the clash on the bottom of the base to get the better of the inclination to skid or turn over. They are by and large economic merely up to a tallness of 1.800m. Mass walls can be constructed of semi-engineering quality bricks bedded in a 1:3 cement howitzer or of aggregate concrete. Mass concrete could hold some light fabric support to command surface checking. Natural rock is suited for little walls up to 1.000m high, but by and large it is used as a facing stuff for walls up to 1.000m high, but by and large it is used as a facing stuff for wall over 1.000m. Typical illustrations of mass retaining walls are shown in figure 9 and 10: Figure 9: Brick Mass Retaining Walls Figure 10: Mass Concrete Retaining Wall with Stone Facings Cantilever walls Cantilever walls are normally of strengthened concrete, and work on the rules of purchase. Two basic signifiers can be considered: a base with a big heel so that the mass of the wall with a big toe ( figure 10 ) . The figure shows typical subdivisions and forms of support encountered with these basic signifiers of cantilever retaining wall. The chief steel occurs on the tenseness face of the wall, and nominal steel ( 0.15 % of the cross-sectional country of the wall ) is really frequently included in the opposite face to command the shrinking snap that occurs in unmoved concrete work. Reinforcement demands, bending, manufacturing and puting are dealt with in item in the subdivision on the strengthened concrete. Reinforced cantilever walls have an economic tallness scope of 1.200-6.000m. Walls in surplus of this tallness have been economically constructed utilizing prestressing techniques. Any lasting facing stuff may be applied to the surface to better the visual aspect of the wall, but it must be remembered that such coatings are cosmetic and add nil to the structural strength of the wall. Figure 10: Reinforced Concrete Cantilever Retaining Walls Counterfort Retaining Walls These walls can be constructed of strengthened or prestressed concrete, and are considered suited if the tallness is over 4.500m. The counterforts are triangular beams placed at suited Centres behind the root and above the base to enable the root and base to move as slabs crossing horizontally over or under the counterforts. Figure 11 and figure 12 show a typical subdivision and form of support for a counterofrt retaining wall. If the counterforts are placed on the face of the root they are termed buttresses, and the whole agreement is called a buttress-retaining wall. The design and building rules are similar in the two formats. Figure 11: Reinforced Concrete Counterfort Retaining Wall Figure 12: Reinforced Concrete Counterfort Retaining Wall Reinforced masonry retaining walls Steel support may be used in brick retaining walls to defy tensile forces and to forestall the effects of shear. A brick bonding agreement known as Quetta bond is used to make a unvarying distribution of perpendicular nothingnesss. Vertical steel support is tied to the foundation support and spaced to co-occur with purpose-built nothingnesss. The nothingnesss are filled with concrete to bring forth a series of strengthened concrete mini-columns within the wall when the brickwork is completed. Where visual aspect is non of import, or the wall is to have a surface intervention, support and unmoved concrete within hollow concrete block work provide for economical and functional building. Figure 13 shows the application of standard-profile, hollow, heavy concrete blocks lay in stretcher bond as lasting formwork to uninterrupted perpendicular columns. Figure 13: Reinforced Concrete Block Retaining Wall The height potency and slenderness ratio ( effectual tallness to width ) for reinforced masonry walls can be enhanced by post-tensioning the construction. For intents of brick walls there are a figure of building options, including: Quetta bond with steel bars concrete in the nothingnesss ; Stretcher-bonded broad pit with strengthened steel bars coated for corrosion protection ; Solid wall of pierced bricks with uninterrupted nothingnesss incorporating grouted steel support bars. Some illustrations are shown in figure 14: Figure 14: Post-tensioned Brick Retaining Walls Decision Based on treatment shown on above, I would wish to choose Cantilever retaining wall as the most suited retaining wall for the undertaking where is located at hilly country which consists of 20 units of luxury cottages. Equally shown as above, a cantilever retaining wall is a signifier of masonry installing that holds a big sum of Earth in topographic point. The cantilever design is merely one of several fluctuations on a retaining wall design, utilizing assorted rules to pull off earth tonss. Cantilever retaining wall has an economic tallness scope of 1.200-6.000m. This type of retaining wall is suited for cottages because the tallness is sufficient to back up the cottages. A concrete cantilever retaining wall uses a comparatively thin root of steel-reinforced, cast-in-place, concrete or mortared masonry. In a cantilever retaining wall design, an Earth force per unit area vector acts horizontally against the side of the wall. The bottom portion of the wall presents a gravitation vector downward. That gravitation vector produces an opposite force upward. The ensuing vector counters the Earth force per unit area vector, and pushes back against the Earth burden. This type of retaining wall is more stable compared to the other three types which stated on above in order to construct 20 units of luxury cottages because the tonss are distributed every bit. Retaining wall design is evaluated to chair the effects of a landslide. Retaining walls can be helpful in protecting dirt against the sorts of motion associated with these natural catastrophes. Looking at landslide hazard and the hazard of liquefaction, the H2O impregnation of Earth, is portion of measuring how a retaining wall plants. Cantilever retaining wall is one that consists of a unvarying thickness wall which is tied to a terms. It located at the cellar of cottages. Therefore, cantilever retaining wall will keep back the Earth. Soil eroding, landslides and environment catastrophes are less likely to be occurred. In other words, checking and prostration of 20 units of luxury cottages are avoided. Weep holes are designed in the cantilever retaining wall to let go of the extra force per unit area created by a accrued H2O and helps in stabilising the retaining wall. This ensures the edifice will non fall in due to the fast flow of H2O on the hill. In decision, a suited retaining wall is able to stabilise the dirt and avoid overturning and sliding of edifice. Beside, a suited retaining wall can besides assist in salvaging the building cost. Therefore, cantilever retaining wall is the most suited retaining wall for 20 units of luxury cottages which are located on the hilly country.