LEARNING OUTCOME 1 (QUESTIONS P1, P2, P3, M1& D1)
QUESTION P1-Discuss earthworks activities, equipment and techniques
Earthwork can be defined as a construction process that precedes the construction of the road structure itself and affects only the natural form of the ground or earth.
Equipment and type typical applications
– Bulldozers – Loosening rocks, short distance sand removal
– Motor graders – Forming pavement layers and fills
– Cranes – Excavating, setting and handling, lifting
– Trucks and Wagons – Hauling Operations
– Rollers – Compaction
– Loaders – Digging, Filling, Cleaning
– Scrapers – Digging, Loading, Transporting, Dumping, Spreading
Basic Earthwork and Techniques
1. Removal and Excavation
Usually the first operation in earthwork before filling or excavating, removing trees, roots, debris, and debris from planned or designated areas of planned excavation and areas where embankments or obstructions are to be removed. It can be defined as removing other objectionable material. .
Roadway and Drainage Excavation – Removal of all excavated material for construction such as cuts, fills, embankments, ditches, crossings, etc. to allow construction of pipe culverts, concrete box culverts. including excavating and leveling roads and ditches, foundations for bridges, retaining walls, and other structures required for specific jobs.
Lawn Pits – If there is not enough material for fill from pits within road right-of-way limits, additional suitable material is usually obtained from lawn pits.
When road grade lines need to be raised above the existing ground level by a certain distance to comply with design standards or to prevent highway damage from exposure to surface or groundwater. , used on highways.
Rolling earthen embankment construction – A thin layer (15-30 cm) of loose soil is rolled until it is dense enough to reach the desired height before laying the next layer.
- Finishing operations
Embankment foundations built in wetlands require special treatment to avoid failure. Gravity subsidence, partial or full excavation, blasting, jetting, vertical sand drainage, reinforcement with engineering fabrics, etc. Shoulder trimming, side and groove banking, cut sections (ripping, forming, compacting), traversing slope section. This process is typically performed as the work nears completion.
QUESTION P2 -Describe methods and techniques used to create complex foundations, piling works and drainage works
– Deep Foundations:
Foundations built deep enough below the surface of the earth, on which man-made facilities such as piles and wells are installed. Techniques used; pile foundation, well foundation, caisson.
Pile Foundation: A foundation usually consisting of a spread foundation or trellis base supported by lower piles. Piles distribute the load of a structure to the ground either by friction alone or by friction in combination with end bearings.
Driven Pile Foundation – These piles are pre-assembled prior to installation on site. If the driven pile is made of concrete, it is prefabricated. These stakes are driven in with a ram hammer. When driven into granular soil, these stakes displace the same volume of soil. This helps compact the soil around the side of the pile, resulting in compaction of the soil. A pile that compacts adjacent soil is also called a compression pile. This soil compaction increases its bearing capacity.
Cast-in-Place Foundation – Cast-in-place piles are concrete piles. These piles are constructed by drilling holes in the ground to the required depth and filling the holes with concrete.
Reinforcing materials are also used in concrete, depending on the requirements.
Drive-in vs. cast-in-place piles – Drive-in vs. cast-in-place piles have the advantages of drive-in and cast-in-place piles. Installation of driven on-site concrete piles is carried out as follows: A steel shell with a pile diameter is driven into the ground using a mandrel inserted into the shell. After the shell is driven, the mandrel is removed and concrete is poured into the shell. The shell is made of corrugated and reinforced thin steel sheets (nanotube pile) or tubes (Armco), welded tubes, or traditional seamless tubes). This type of pile is called a shell pile. The shell-less type is formed by pulling back the shell when placing concrete. In both types of posts, the bottom of the shell is closed with a conical tip that can be separated from the shell. Enlarged bulges can be formed in both types of piles by pouring concrete out of the shell.
– Spread Footing Foundations:
These are foundations built by increasing the area at the base of the structure by offsetting. In these footings, an extension, called a footing, is given below the base of the wall or column by providing an offset. The techniques used are:
Wall Foundation: Usually consists of several layers of bricks, the lowest layer usually twice the thickness of the wall above. This type of foundation increases the base width of the wall by offsetting it by 5 cm (1/4 brick length) on each side of the wall. Each course is typically 10cm deep However, in some cases, the soil layer is carried out with a depth of 20 cm.
Masonry Column Foundation: These are insulated foundations used to support individual piers
and columns of brick or masonry. They are installed in the wall foundation after offsetting the foundation concrete by 15 cm on all sides.
Concrete column foundation: either stepped, slate or sloping, with protrusions in the concrete. The base is also reinforced to support heavy loads. The planned Reinforcement
consists of steel bars and is laid in both directions. Concrete column foundations are either single foundations or composite foundations. Individual foundations are used to support individual
supports, and composite foundations are used when for space reasons the different supports cannot be cantilevered on all sides.
– Grillage Foundation:
This is a foundation consisting of one or two layers of wood or rolled steel profiles, the space is filled with concrete and is known as a Grillage Foundation. This type of construction avoids deep excavations and provides the necessary area underfoot of the structure to reduce pressure strength within the safe load-bearing capacity of the ground. Technology used;
steel lattice foundation/woodwork lattice foundation
A foundation covering the entire mat surface with thick RCC plates, useful for public buildings, office buildings, school buildings, residential areas, etc. when the soil conditions are so poor that the load-bearing capacity of the soil is so low that individual application is not possible.
is a foundation work that excavates in steps of short length and uniform thickness and masonry on a horizontal concrete floor.
R.C.C piles can be driven along the base concrete on the slope side if the structure is subject to physical slippage.
Inverted Arch Foundation:
foundation consisting of inverted arches between piers. Loads are transferred from the piers to the ground by building the arch in an inverted position at its base. An inverted arch is about one-fifth to one-tenth the height of its span and is usually made of half-brick rings. The position of the arch can be either along the row of piers or across the row of piers, depending on the nature of the ground and the type of land occupied.
QUESTION P3 –Describe methods and techniques used in culvert construction, underpass construction and provision for utilities.
culvert construction – A culvert is defined as a tunnel structure built under a road or railroad to provide cross drainage or carry electrical and other cables from side to side. It is completely surrounded by earth and soil. Culvert designs are based on hydraulics, water level, roadway height, and other considerations. These are used in a controlled manner for water flow.
Pipe Culvert (Single or Multiple) –These are common culverts and have a rounded shape. Passages can exist individually or in multiples. When using a single pipe culvert, install a culvert with a larger diameter. If the duct width is greater than this, select multiple pipe culverts.
Elbow culvert(s) – These look like semi-circular culverts. Elbow culverts are suitable for larger water flows, but the flow must be steady. The arc shape makes it easy to carry draining fish and sewage to the exit without having to collect it at the entrance or bottom of the drain.
Box culvert(s) – These culverts are rectangular and usually constructed of concrete.
We also perform reinforcement during box culvert construction. These are used to handle rainwater and are therefore useless during the dry season. It can also be used as a passageway across tracks and roads during the dry season for animals, etc.
Arch Culvert – An arch culvert is similar to a pipe arch culvert, but in this case there is an artificial floor under the arch. For narrow aisles, it is widely used. The artificial floor is made of concrete, and the arch is also made of concrete. Steel arch culverts are also available, but are very expensive.
Bridge Gully –A culvert is built over a canal or river and is also used as a road bridge for vehicles. The foundations of these culverts are laid below the surface of the earth. A line of culverts is laid and a pavement is laid over the line of culverts. Generally, these are rectangular culverts that can replace box culverts when artificial soil is not required.
Construction of Underpasses and Provision of Utilities.
An underpass or subway is a tunnel containing a road or sidewalk that passes under a road or railroad. You can also build underpasses to allow wildlife to safely pass under traffic paths.
Construction Methods There are three main methods of construction for
underpasses: precast concrete, cast-in-place concrete, or pressure-drilled elements.
Precast Concrete Units – These are often manufactured as standard units and can be supplied to the site as complete box type open sections, portal frame segments or separate wall and roof units. Box units are typically joined with preformed weather-stripping with socket and Tenon joints. Floor and roof connection plates are used to screw the unit
For pre-stressed portal frame members, the lower geo-membrane is placed on a concrete slab, on top of which is placed a continuous concrete bearing slab (typically 300mm wide x 25mm deep). Then apply a lubricant to keep the unit in place and reduce friction due to stress. The wall and roof unit system consists of prefabricated units that are put into place on site with flooring using the units as formwork. Roof units are then placed and loading plates are cast in situ, with loading requirements dictating the thickness.
Pressure Drill Unit – Requires bentonite slurry as a lubricant. To transfer the thrust load, the unit must contact the edge directly rather than a pre-formed weather-strip. This joining method should allow edge contact for jacking, but can accept sealant from the inside. This is accomplished by forming a mortar-filled rebate joint prior to applying the sealant.
Cast in Place – These underpasses are constructed in the same manner as any other underground tunnel construction.
QUESTION M1 –Analyze methods and techniques used in large complex earthmoving operations and deep excavations.
Full open cut method – can be divided into two main types: inclined full open cut and cantilever full open cut. The former is considered more economical as the excavated side is slanted and does not need to support a retaining foundation wall. However, if the slope is fairly shallow or if the excavation is significantly deeper, it will be expensive. The latter requires a retaining wall to support the foundation floor and prevent the foundation wall from collapsing, but neither supports nor embankments are required. Therefore, it is not possible to generalize which method is more cost-effective. Economic procedures can be differentiated based on the results of analysis, design and evaluation.
Brace Drilling Method – Brace drilling is the placement of horizontal braces in front of a retaining wall to support the material pressure of the excavated wall. The brace system consists of transoms, braces, mullions, end braces and corner braces. The transmission of earth pressure by the transom to the horizontal braces and the purpose of the corner and end braces is to reduce the transom span without increasing the number of braces. The center post prevents the strut from breaking due to its own weight.
Anchor Installation Method – In this method, anchors are placed to counteract earth pressure. Structures and components of anchor drilling technology. The bonded part of the anchor provides the anchoring force acting against the earth pressure and the unbonded part of the anchor transmits the pressure to the anchor head. An anchor head transfers the load to the retaining wall. The anchoring force greatly depends on the strength of the ground
The stronger the soil, the greater the holding force. This technique is not suitable for clayey and granular soils with a high water table. Finally, it takes a short time to complete drilling very efficiently, suitable for large areas and shallow depths.
Island Excavation Method – A method of excavating the center of an excavation area and placing the excavated material near the retaining wall to create an embankment. After this, most structures are built in the middle of the excavation. Then the slope is excavated and the stanchions are placed between the retaining wall and the main structure. Finally, the stanchions are removed and the rest of the structure assembled. It may be necessary to use anchor or brace techniques to remove soil from the slope, especially if the excavation is too deep.
Zoning method – The zoning method uses an underground wall as a retaining wall. Long-span wall deformation is greater than short-span wall deformation. Thus, dividing the excavation area into smaller areas to reduce wall deformation and subsidence, as shown in
, reduces wall deflection for longer spans. Excavation begins in area B, leaving area A to support the walls of area B. Next, a stanchion is installed in area B and excavation is started in area A. This process continues step by step until all excavations are completed. It can be clearly seen that if the area is not divided into smaller areas, the diaphragm wall will be considerably more loaded and therefore more flexed.
Top Down Excavation Method – In this method, construction begins from the top down of the excavation, with superstructure construction starting after the first slab construction is complete. So the slab is built after each excavation phase is completed
QUESTION D1: Evaluate methods and techniques used to deal with issues of ground and slope stability
The most commonly used slope stabilization techniques are categorized as:
1. Hydrological Techniques – The introduction of hydrological techniques lowers the groundwater table and reduces the water content of soil/rock materials.
2. Chemical and Mechanical Techniques – These chemical and mechanical stabilization techniques increase the shear strength of critical soils/rock masses by external means. In addition, minimizing the external forces that trigger slope failure can also increase the shear strength of the slope.
These methods can be further described as:
a) Geometric Method
In this method, slope stabilization can be achieved by:
– Eliminates loads from the top of the slope – This reduces shear stress at critical levels and improves stability.
– Applied pressure berm at foot of embankment – This provides additional security against failed rollovers.
b) Hydrological method
In this method, stabilization of slopes by hydrological method can be achieved by: stress and finally stable.
– Use of inverse filters – This reduces pipelines and reduces stability, especially for dams.
c) Chemical and mechanical methods
Slope stabilization using chemical and mechanical methods can be achieved in the following ways. A clod of earth that displaces air and water through cracks and fissures. Mortar is a mixture of cement and water. However, sand, clay, rock dust, fly ash, etc. can be used instead of cement. This reduces the effort required for stabilization work, especially in the case of large amounts of cracks and fissures.
– Construction of retaining structures. B. Concrete Gravity Walls or Cantilever Walls
– Assembly of Gabion Structures, Cot Walls, Fill Pile – To Provide Overturn Resistance
– Assembly of Lime and Cement Columns
– Installation of Ground Anchors, Rock Anchors, Roots B. stakes etc. – provide effective tension around stone blocks
– plant shrubs and grasses – reduce soil erosion
LEARNING OUTCOME 2 (QUESTIONS P4, P5, M2& D2)
QUESTION P4 –Identify the hazards, risks and safety arrangements for excavations, working in confined spaces, working on structures and working within temporary works on highways
Part (a) Identify the hazards, risks
Excavation, as defined by OHSA, can be termed as an artificial cut, void, trench or depression in the earth’s surface created by the removal of soil and can entail a number of hazards such as:
Cave ins – walls collapse without a warning hence workers have no time to move out of the way, a cubic yard of earth could be fatally crushed and suffocated.
Electrocution/explosions – Careless excavation can damage utility lines such as gas lines, fuel lines, and even large water collection tunnels, causing explosions, floods, and even electric shocks and injuring workers. Residents immediately, causing damage and death.
Excavation Surface Collapse – When constructing highways water mains and sewer networks, deep cuts are made to reach the required level. These shafts are narrow or confined, and depending on the magnitude of the vibrations caused by the movement of the geothermal power plant, they can collapse, causing casualties and even death to workers and bystanders.
Material falling on people – This is common in deep excavations where falling objects can hit workers working underground
Falling Persons or Vehicles – In deep unprotected highway cuts and excavations, vehicles that lose control can fall while excavating, causing death or serious injury to drivers, passengers and even construction equipment at the bottom of the excavation. may give
Nearby structures collapsing during excavation – Excavation occurring near buildings can affect the stress isobars of foundations. This minimizes the effective area of the foundation and can cause nearby buildings to collapse.
Part (b) safety arrangements for excavations
According to an Occupational Safety and Health Administration investigation, the main reason dugouts collapsed was that they were not properly protected. They suggested the protection system be as follows
– Support the trench with supports such as planks or hydraulic jacks
– Shielding the trench with a trench box should always be done properly.
– Collapse should be avoided by supporting the sides by hitting or supporting the sides with a sheet.
– Slope the ground
– Set the ground
– Materials from excavations should be stored at a safe distance from excavations to reduce the risk of falling on people.
– Adding barriers to excavations is an important precaution to prevent people from falling into excavations.
– It is safer to keep vehicles completely clear of the excavation area, but barriers and stop blocks can be used to reduce this hazard when necessary.
– Cable, pipe and utility maps should be used to ensure that underground utilities are known and marked above ground or ideally avoided altogether.
– In areas with underground installations, mechanical equipment should be avoided and spades and shovels should be used instead.
– Pickaxes and forks should be avoided as they tend to pierce cables and pipes.
– Flooding can be avoided by ensuring that proper pumping equipment is in place so that water entering the excavation can be easily pumped to a safe location.
QUESTION P5: Develop and present a site safety plan, risk assessments and method statements for a given civil engineering activity.
|Hazard identified||Person at risk||Controls in place||Risk rating||Actions to reduce risk|
|Damages to underground utility.||Operatives||At all stages of excavation, a competent person should supervise the work and give workers clear instructions on how to work safely in the excavation. If plants are used in trenches, workers should not be in the trenches while the machine is running. Before work can begin, the area must be scanned for underground service and a drilling permit issued. Only hand dig near the underground facilities. Wires near excavations should be insulated by his FM electrician who issues an insulation permit. Excavation areas must be protected with 2M Heras fencing.||C8||Written inspection records of excavation must be kept by qualified personnel.|
|Crushing||Operatives||If trench depth is required, barriers should be provided along with extended pole boards and ladders for safe entry and exit. Workers should ensure that shoring, etc., is satisfactorily completed prior to descending into the trench and gaining access using appropriate access equipment. Excavations should not be adjacent to buildings and should not keep heavy plants away from edges. Stop blocks should be placed behind the wheels of a vehicle that rolls over during excavation. Do not store materials, waste, or equipment near excavation.||C8.||Written inspection records of excavation must be kept by qualified personnel.|
|safety of excavation||Public, Students & LU Staff||This area should be fenced with a 2 meter high Heras fence and located at a safe distance from the excavation. Ring fence works. Fence panels must be double bolted at all joints and restricted to authorized contractors only. Facilities and access facilities must also be protected when not in use||C8||Written inspection records of excavation must be kept by qualified personnel.|
|Lone Working||Operative||Excavation work is a minimum of two person work. Overtime is a two-person system by talented staff||C5|
|falling objects||Operative Public, Students & LU Staff||This area should be fenced with a 2 meter high Heras fence and located at a safe distance from the excavation. Ring fence works. A fall protection system should be installed around the excavation pit. Place blocks at a safe distance from the excavation to prevent vehicles from falling into the excavation. PPE – Helmets and safety shoes must be worn.||C8||Written inspection records of excavation must be kept by qualified personnel..|
|nearby structures and buildings stability reduction.||Operative Public, Students & LU Staff||Excavations in the immediate vicinity of buildings and structures must be inspected by a qualified person before work commences||B10||Written inspection records of excavation must be kept by qualified personnel.|
|traffic collisions||Operative Public, Students & LU Staff||Vehicles should be kept as far away as possible by warning signs and barriers forming pedestrian walkways. This area should be lit up at night.||C8||Written inspection records of excavation must be kept by qualified personnel.|
|Hazard identified||Person at risk||Controls in place||Risk rating||Actions to reduce risk|
|Hazardous substances in ground||Operative Public, Students & LU Staff||Any hazards discovered before or after the start of work must be registered in the inspection report and corrective action taken by the contractor. Exhaust gases should not be placed near the top of excavations.||C6||Written inspection records of excavation must be kept by qualified personnel.|
|Contractor Competence||Operative Public, Students & LU Staff||The supervisor checks the contractor’s competence before signing the contract. Contractor employees must have completed at least a road construction course. The SO should request a copy of the drilling inspection report.||C6||Written inspection records of excavation must be kept by qualified personnel.|
|Cutting/severing||Operatives||Operators using power saws must ensure they are wearing appropriate PPE. Operators must wear hearing protection, safety goggles, gloves, and helmets. Make sure first aid kits and competent first responders are available. Employees should wash their hands before eating.||C8||Written inspection records of excavation must be kept by qualified personnel.|
QUESTION D2 Justify a site safety plan, risk assessments and method statements report for activities related to a given civil engineering project.
The above plan is prepared based on the table below for assessing risk into five category and rating using the harm-likely-hood matrix on the left then for an excavation activity the following risk assessment plan can be developed. It is therefore my justification
< 3 days
|1 – 4||C||No further immediate action Review periodical|
|5 – 9||C||Re-assess during next review.|
|10 – 16||B||Within 3 months. (Improvement Notice|
|17 – 25||A||Immediate (Prohibition Notice)|
QUESTION M2 –Discuss health & safety legislation and codes of practice related to civil engineering sites.
The universal law for health and safety laws relating to construction is
a. Health and Safety at Work Act 1974 (HSW Act) – Employers have a duty to ensure the health and safety of workers and others who may be affected by their work activities.
- b) Work Regulations 1989 BC – Requiresemployers to avoid and prevent electrical injuries.
c) Occupational Health and SafetyManagement Regulations 1999 – Requires employers to carry out appropriate and adequate risk assessments
however, the following Regulations are also used in special projects and are specific to china
- d) Metallurgical Enterprises and Safety Regulations for the Production of Non-Ferrous Metals (04/01/2018) – The bodyof the Codeidentifies and investigates a number of physical hazards commonly encountered in the production of non-ferrous metals. These include noise, vibration, thermal stress, radiation, confined spaces, dust and chemicals. Separate chapters deal with furnaces, molten metals, and
- e) Notificationof the Competent Departmentof the State Administration of Work Safety on Amendment of Regulations on Management of Labor Protection Goods by Employers Municipality directly under the Central Government, Production and Construction Corps of Xinjiang, Provincial Coal Mine Safety Supervision Bureau and relevant central enterprises.
f) Notification of Ministry of Emergency Situations on Comprehensive Implementation of Safety Risk Assessment System and Announcement of Obligations in Companies Dealing with Hazardous Chemicals 04 September 2018 21 September 2018
In addition to these notifications, the following criteria: .
g) CHINA ADR: JT/T 617.X-2018 Regulations on Transport of Dangerous Goods by Road 06.09.2018
h) GB/T 35076-2018 Public Safety Requirements for Potentially Explosive Deposits by Chemical Synthesis 08/13/ 2018
LEARNING OUTCOME 3 (QUESTIONS P6, P7 & M3)
QUESTION P6 –Evaluate the environmental, quality, geotechnical and economic contexts of a given civil engineering problem.
- Environmental problems
Production of dust –almost all civil engineering project involve excavation to prepare the site (construction area) and excavation to mine the construction materials, this when done on dry season and on loose soils leads to generation of dust which is an environmental concern.
Production of noise –whether using new or old machinery, construction of major civil engineering projects involves heavy plant and machinery which makes a lot of noise in their operation, this added to the fact that dry materials especially aggregate will make noise during placing and compaction becomes and environmental concern especially in urban area or high population density rural areas.
Contamination of land and water –this is mostly the case when the sites being excavated have a lot of dry and water soluble elements, in case it rains, most of this materials flow to river causing further siltation and contamination therefore becoming an environmental concern
Visual impacts/ aesthetics –some projects occupy vast footing area or appropriately long stretch across a major environmental recreation area, if this project don’t blend with the surrounding environment they may lead to loss of aesthetics thus becoming an environmental concern
- Economic problems
Inflation –civil engineering project often takes a lot time to complete, this bring the problems of changes in construction materials making it hard for clients and contractors to set a truly fixed value of a projects, this therefore becomes a major issue if the project is to take a long duration.
Interest rates/ depreciation –civil engineering works involve movement of a lot of money to many players, be it through procuring or through overheads to machinery suppliers therefore is the project experiences a lot of delays due to weather, rebellion etc. interest rates become an economic concern to stakeholders and may lead to the detriment of the project.
Growth of income – wages and salaries keep on changing, and the construction project being one of the major employers may experience a lot of economic problem in case there is a skewed growth in come during the project execution, changes in wages and salary may either lead to lower profit for contactors or higher investment capital for developers for the same project.
Population –most civil engineering works are undertaken to benefit or serve the need of the population. Thus rapid growth in population may lead to increased stress in the existing or ongoing construction projects. This would normally lead to expansion of infrastructure to meet the increased demand. However, this becomes an economic problem because infrastructural project is expensive and time consuming and therefore unplanned surges in population growth is undesirable.
Consumer sentiments –every infrastructure is laid to serve the people and generate revenue for the developer, it therefore must be up to the expectation and taste or preference of the public. Therefore, public sentiments become an economic concern before undertaking the project.
- Geotechnical problems
Flow problems –almost all civil engineering works are laid on soil for foundations or made of soil as a major construction material, therefore understanding the soil drainage, permeability and hydraulic conductivity becomes a major concern in all construction civil engineering works, these aspects are called the soil flow problems as they influence its liquefaction.
Deformation problems –all foundations are underlain by a soil material, this materials depending on it physical structure and composition will settle differentially od uniformly. Understanding how the soil will consolidate, settle, expand or shrink becomes a major problem to be evaluated in all civil engineering works.
Failure load problems/ bearing capacity/shear strength –this problem is used by engineer to understand just how much a soil can carry, or how steep an excavation side can be. Understanding the soil shear strength and bearing capacity properties becomes a major civil engineering geotechnical concern to be addressed before any works is designed or undertaken.
QUESTION P7 &D3 (answered together)–Propose a solution to a given civil engineering problem &Justify the selection of specific features in the development of a civil engineering solution
Solution to its environmental problems
- Conducting and environmental impact assessment before a project is approved
This would mean that before any works is approved, it be investigated on how it will affect the ecology of the surrounding area. This would involve screening the project to determine if it really requires the EIA, then scoping to determine the major environmental impacts of the project, then proposing mitigation measures on how to remedy the major environmental issues, then requesting the developer to show how they will be implementing the mitigation proposed, and finally monitoring if the developers are observing the mitigation proposed and eventually conducting an audit on the whole process to test its effectiveness. If the developer cannot deal with the proposed mitigation, their project should be canceled from implementation.
Solution to its economic problems
- Conducting a feasibility/ market study before a project is designed
This would mean that before any works is approved, it be investigated on how it will affect the economy of surrounding area and also how the surrounding area will impact the economy of the project. This would involve conduction surveys on population, growth rate and projections, settlement and distributions and existing condition to gauge the project investment size, capital and maintenance cost. Also studying inflation intervals and rates would help the contactors to make informed bids to avoid future losses. Other economic aspect like the expected IRR (internal rate of return) and project construction periods should be considered before making any designs to avoid dead investments and unwarranted depreciations.
Solution to its geotechnical problems
- Conducting a site investigation before a project is designed
This would involve studying the soil properties of the construction area to determine flow conditions, deformation and failure load problems this would help avoid unwarranted failures in the project lifecycle. Also doing the same in quarries would improve safety of workers.
QUESTION M3 –Illustrate how the environmental, geotechnical, quality and economic contexts of a problem are addressed through a proposal
How environmental context is addressed through a proposal
- By submitting an EIA (environmental impact assessment) report conducted by registered (lead) expert) as part of proposal
The report usually contains
- Executive summary
- The proposed project
- Approach and methodology
- Potential alternatives
- Study limits
- Environmental policy, legislative and planning framework
- Existing environmental conditions
- Scoping the environmental impacts
- Scooping the assessment
- Scooping the environmental management aspects
- Technical appendices
- Administrative appendices – this will be consultants itinerary, etc.
How geotechnical context is addressed through a proposal
- By submitting a geotechnical report conducted by a qualified geotechnical engineer a part of proposal
The report usually contains
- Site location map
- A plan view of location of boring
- Photos of soil boring and samples
- Boring logs
- Laboratory test results
- Other special graphical representation
How geotechnical context is addressed through a proposal
- By submitting a feasibility study report conducted by a qualified graduate or professional civil engineer as a part of proposal
The report usually contains possible alternatives of the project and their construction and maintenance cost, construction durations and technological requirements of each alternative.
LEARNING OUTCOME 4 (QUESTIONS P8, P9, M4 & D3)
QUESTION P8 Describe methods and techniques used in highway design
High way design involves designing various components separately then joining to make a route. The main design methods maybe dividend into
- Highway Pavement design methods
In this category or design technique the highway pavement or the material comprising of a highway and their thicknesses are designed.
The main methods conventionally used are;
- Mechanistic-empirical design methods.
In this category, certain material is proposed and its mechanical properties are studied and analytically used to design a highway pavement thickness, the main properties used are; material modulus of elasticity, allowable deflection of flexible pavements, materials Poisson ratios, the expected axle wheel loads. Using those property, the pavement layer thickness is obtained.
The methods used are
- Layered elastic model
- Boussinessq’s (single layer method)
- Burmister’s (two-layer method)
- Dynamic elastic model
- Viscoelastic model
Using either of the above models one is able to determine stress, strain and deflection in given highway design arrangements hence assess its effectiveness.
- Empirical design methods.
This method is usually based on experience and experimentation than on the analytical aspect of a material. There are numerous methods under this category and are either based on physical properties or strength parameter of soil subgrade and therefore may be done with or without soil strength test.
The main method used under this design technique are
- Group index method
A group index is assigned to soil based on its Unterberg indexes (Liquid limits and plasticity index). The higher the group index the weaker the subgrade soil. A chart of Group index versus thickness and the curve are used to determine pavement thickness.
- CBR method
This method has an advantage in that it gives the total pavement thickness as well as intermediate layers’ thickness provided the CBR values of the material in courses is known. A log chart of CBR and depth of construction as well traffic class is used to obtain pavement thickness.
- AASHTO methods
In this method the paving material is classified and awarded as structural number based on its strength and other engineering property. Also the traffic class is obtained and curves chart with structural number on x-axis and pavement thickness of y-axis used to design a highway pavement.
- Highway geometric design methods
This involves designing the layout of a highway considering design speed, vehicle characteristics, maximum gradients, sight distances, road safety, topography, environmental consideration and human settlements as control points.
It may be divided into
- Horizontal alignments design – under this, curves, widening and super elevation are designed considering design speed, maximum radius and sight distances.
The main output is the staking out data for all curves and intersections.
- Vertical alignments design –under this the slopes are designed and maximum gradient levels are obtained for field use.
- Intersection design/ junction layout –under this all intersection are studied and designed accordingly to facilitate effective movement of traffic from minor to major roads and vice versa. The intersection may be a channelized or signalized.
- Round about design –in this method an intersection between two major roads or minor road is marked by having a rotary intersection called roundabouts.
QUESTION P9 –Develop a civil engineering design proposal for a new infrastructure project.
|PROJECT TILE :|
|Construction Of Beijing New Waste Water Treatment Plant|
|Construction of a new sewer line to serve the increasing population of Beijing town, the newer sewer line will be comprising of a 20 km steel sewer pipe of diameter number 500 mm, 40 new manhole 2m deep and 1.5-meter-wide circular in shape distributed along the pipeline to act sewer inlet in the new settlement areas. The will be a new treatment plant constructed north of the existing treatment plant with an average capacity of 100,000 cubic meter per day and new administration offices.|
|PROJECT FEASIBILITY STUDY|
|Alternatives/ possible actions||Construction cost||Maintenance cost per year||Period to maintenance||Technical limitation||Preference|
|Onsite waste water treatment||100 million||7.5 million||5 years||Land
|Increasing capacity of the existing treatment plant||50 million||15 million||2 years||Effluent quality||Not preferable|
|Replacing the old sewer treatment system with a new one||105 million||2.5 million||15 years||None||Most Preferred|
|PROJECT ENVIRONMENTAL IMPACT ASSESSMENT STUDY|
|Dust||Major||Excavating trench and site late in evening and early in morning||Effective|
|Gasses (emission during operation)||Minor||Encasing biological ponds to harvest methane for reuses||Effective|
|Acidification at discharge point||Low||Using lime to neutralize water||Effective|
|PROJECT GEOTECHNICAL INVESTIAGTION STUDY|
|Parameter||Project requirement||Factor of safety||Remark|
|Soil bearing capacity = 400||200||2||Sufficient|
|Uplift = 400||Self-weight=600||1.5||Sufficient|
QUESTION M4 Analyze methods and techniques used to create bridge foundations, flexible highway construction foundation criteria and related geotechnical parameters,
methods and techniques used to create bridge foundations
- Spread foundation – used when there is least scouring and hard ground start from (1.5-3) m underneath the level of watercourse.
- Raft foundation –untiled where water course bed contains delicate clay and silt.
- Pile foundation bridge –used where there is extremely delicate soil and hard strata are not accessible at a sensible profundity.
- Well foundation bridge –suitable on soils having a sandy and weighty scouring is expected due to huge velocity of approach of the river.
- Caisson bridge foundation –utilized where is hard layer close to river bed and there is exorbitant water profundity that isn’t monetarily strong to eliminate the empower sinking wells for foundation.
- Grillage foundation –used for weighty and separated footing of wharfs where deep foundations are to be stayed away from also where subsoil conditions are poor.
- Inverted arc foundation –used where there is possibility of inconsistent settlement.
flexible highway construction foundation criteria
the method used to construct the flexible foundation are
- Compaction – materials are compacted to their maximum dry density using rollers at their optimum moisture content.
- Stabilization – materials are stabilized by adding lime or cement to increase their CBR
- Improvement –materials are blended or mixed together to a composite material to improve their respective strength, moderate their Unterberg limits and CBR.
related geotechnical parameters
- Materials California bearing ratio
- Materials Unterberg limits
- Materials maximum dry density
- Materials optimum moisture content
- Foundation soil bearing capacity
- Foundation soil settlement
- Foundation soil modulus of elasticity
- Soil classification
- Jie Chen, Zan Yang & Ya “pulling, foundations and earthworks plants machinery and techniques (http://dx.doi.org/10.1080/02673037.2013.873392)
- Jean Heilman Grier (April 13, 2020) “China: construction safety and hazards”
- Sarah Xuan “China’s Construction Laws”
- Alex Wang (5 February 2007). “Environmental protection in China: the role of law”