Task 1 (LO 1: 1.1 and 1.2)
A tunnel is an underground or underwater passageway, dug through the surrounding soil, earth, rock and enclosed except for entrance and exit, commonly at each end. A pipeline is not a tunnel, though some recent tunnels have used immersed tube construction techniques rather than traditional tunnel boring methods.
A tunnel may be for foot or vehicular road traffic, for rail traffic, or for a canal. The central portions of a rapid transit network are usually in tunnel. Some tunnels are aqueducts to supply water for consumption or for hydroelectric stations or are sewers. Utility tunnels are used for routing steam, chilled water, electrical power or telecommunication cables, as well as connecting buildings for convenient passage of people and equipment. There 4 kinds of tunnelling methods that is widely used. They are (1) Cut and Cover Tunnelling method (2) Drill and Blas Tunnelling method (3) Tunnel boring machine method (TBM) (4) Sequential Excavation Method
Cut and Cover Tunnelling Method
Cut and Cover Tunnelling Method
Cut and Cover Tunnelling Method
Cut and cover tunnelling is a common and well-proven technique for constructing shallow tunnels. The method can accommodate changes in tunnel width and non-uniform shapes and is often adopted in construction of underground stations. Several overlapping works are required to be carried out in using this tunnelling method. Trench excavation, tunnel construction and soil covering of excavated tunnels are three major integral parts of the tunnelling method. Most of these works are similar to other road construction except that the excavation levels involved are deeper. Bulk excavation is often undertaken under a road deck to minimise traffic disruption as well as environmental impacts in terms of dust and noise emissions and visual impact.

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Drill and Blast Tunnelling Method
This tunnelling method involves the use of explosives. Drilling rigs are used to drill blast holes on the proposed tunnel surface to a designated depth for blasting. Explosives and timed detonators are then placed in the blast holes. Once blasting is carried out, waste rocks and soils are transported out of the tunnel before further blasting. Most tunnelling construction in rock involves ground that is somewhere between two extreme conditions of hard rock and soft ground. Hence adequate structural support measures are required when adopting this method for tunnelling.

Drill and Blast Tunnelling Method

Drill and Blast Tunnelling Method

Tunnel Boring Machines Method (TBM)
Tunnel Boring Machine Method
Tunnel Boring Machine Method
Tunnel Boring Machine method is often used for excavating long tunnels. An effective TBM method requires the selection of appropriate equipment for different rock mass and geological conditions. The TBM may be suitable for excavating tunnels which contain competent rocks that can provide adequate geological stability for boring a long section tunnel without structural support. However, extremely hard rock can cause significant wear of the TBM rock cutter and may slow down the progress of the tunnelling works to the point where TBM becomes inefficient and uneconomical and may take longer time than the drill-and-blast tunnelling method.

New Austrian Tunnelling Method (NATM)
New Austrian Tunnelling Method (NATM)

New Austrian Tunnelling Method (NATM)

In NATM method, the excavation location of a proposed tunnel is divided into segments first. The segments are then mined sequentially with supports. Some mining equipment’s such as road-headers and backhoes are commonly used for the tunnel excavation. The ground for excavation must be fully dry for applying the NATM and ground dewatering is also an essential process before the excavation. Another process relates to the ground modifications such as grouting and ground freezing is also common with this method in order to stabilize the soil for tunnelling. This method is relatively slow but is found useful in areas where existing structures such as sewer or subway could not be relocated.

Procedure for Drill and Blast Method
Firstly, we have to survey the shape of the tunnel and then mark the lines to drill with drilling jumbo and to put the explosives.

Surveying the tunnel
Drilling the marked area of the tunnel
Putting the explosives
Surveying the tunnel
Drilling the marked area of the tunnel
Putting the explosives

Then, the detonate the explosives from the safe distance. Ashes and gravels are made due to explosives. So, we need to absorb the ashes with aire ventallator and clear the gravel with dump trucks.
Detonating the explosives
Clearing the gravel with Dump trucks
Dusts and ashes are absorbed by the air ventilator
Detonating the explosives
Clearing the gravel with Dump trucks
Dusts and ashes are absorbed by the air ventilator

Finally, scaling and putting support such as rock bolts processes are occurred. Repeating these steps are needed to reach the required distance.

Scaling the tunnel
Putting support
Scaling the tunnel
Putting support

Procedures for New Austrian Tunnelling Method (NATM) NATM method begins at the top heading, we need to excavate at first then spray shotcrete. Then, steel ribs and rock bolts are installed to support the tunnel. After, top heading has reached the required distance, above steps are continued at the bench. Excavation and shotcreting
Installation of steel ribs and rock bolts
Continuing excavation, shotcreting and installation of steel ribs and rock bolts at the bench
Excavation and shotcreting
Installation of steel ribs and rock bolts
Continuing excavation, shotcreting and installation of steel ribs and rock bolts at the bench

After completion of the excavation and initial support, the waterproofing system is installed sandwiched between initial and final lining, consisting of a protective geotextile, a flexible waterproofing membrane, enhanced by a sectioning system for remedial repair of possible leaks. Installation of waterproof membrane
Installation of waterproof membrane

The last step is the installation of the final lining with mobile steel formwork, which is designed to withstand ground loads, hydrostatic loads and seismic loads according to the design criteria. The final lining can be either reinforced cast-in-place concrete or shotcrete, depending on the length of the tunnel and the variability of the cross section. Filling the inner lining with mobile steel formwork
Filling the inner lining with mobile steel formwork

Task 2a (LO 2: 2.1 and 2.2)
Gravity Dam
Gravity dam is a massive sized dam fabricated from concrete or stone masonry. They are designed to hold back large volumes of water. Gravity dams are well suited for blocking rivers in wide valleys or narrow gorge ways. Since gravity dams must rely on their own weight to hold back water, it is necessary that they are built on a solid foundation of bedrock because gravity holds the dam down to the ground stopping the water in the reservoir pushing it over.
Gravity dams can be classified according to the type of materials which they are construed. There are dams constructed with concrete such as concrete gravity dams, concrete arch dams and concrete buttress dams. And fill dams such as earth dams, earth and rock fill dams and concrete faced rock fill dams.
The materials used to construct fill dams include soil and rock. Water is also a raw material. . Soil is classified by particle size from the smallest, sub microscopic particles called clay; silt, which is also very fine; sand ranging from fine to coarse, where the fine grains are the smallest soil particles our eyes can see; and gravel. Coarser fragments called cobbles and boulders are also used in dam construction but usually as protective outer layers.
The key raw materials for concrete dams are concrete itself and steel reinforcement. The number of other materials and components made by specialty contractors may be used in dam building and include steel gates and tunnel liners, rubber water stops, plastic joint-filling compounds to prohibit the movement of water, electrical controls and wiring, siphons, valves, power generators, a wide assortment of instruments, and even Teflon sheeting to line water outlet structures to prevent turbulence and cavitation which is damage due to swirling water.

Arch Dams
An arch dam is curved in plan, with its convexity towards the upstream side. An arch dam transfers the water pressure and other forces mainly to the abutments by arch action. An arch dam is quite suitable for narrow canyons with strong flanks which are capable of resisting the thrust produced by the arch action.
The section of an arch dam is mostly triangular like a gravity dam but the section is thinner. The arch dam may have a single curvature or double curvature in the vertical plane. Generally, the arch dams of double curvature are more economical and are used in practice

Cross section of Arch Dam

Cross section of Arch Dam

Arch Dam

Arch Dam

Rock fill Dams
A rock fill dam is built of rock fragments and boulders of large size. An impervious membrane is placed on the rock fill on the upstream side to reduce the seepage through the dam. The membrane is usually made of cement concrete or asphaltic concrete.
Rock fill dams in the past were also used to build with steel and timber, but now they are obsolete. A dry rubble cushion is placed between the rock fill and the membrane for the distribution of water load and for providing a support to the membrane. Sometimes, the rock fill dams have an impervious earth core in the middle to check the seepage instead of an impervious upstream membrane. The earth core is placed against a dumped rock fill. It is necessary to provide adequate filters between the earth core and the rock fill on the upstream and downstream sides of the core so that the soil particles are not carried by water and piping does not occur. The side slopes of rock fill are usually kept equal to the angle of repose of rock, Rock fill dams require stronger foundation than those for earth dams.

Cross-section of Rock fill dam

Cross-section of Rock fill dam

Rock fill dam

Rock fill dam

The Construction of the Gravity Dam
Dewatering through tunnels
Dewatering through tunnels
To build a Dam the engineers must first de-water the part of the river valley in which they wish to place the dam. This is achieved by diverting the river through a tunnel. The tunnel is built through one side of the valley around the planned construction area. A series of holes is drilled in the rock. Explosives are placed in the drill holes, blasting takes place and broken rock is then removed. This procedure is repeated many times until the tunnel is completed. Diversion tunnels are often lined with concrete.

Work on diverting the river starts in summer when river levels are low. Earth-moving equipment is used to build a coffer dam upstream of the main construction area. This acts as a barrier to the river and causes it to flow through the diversion tunnel. Another cofferdam is built downstream of the main dam site to prevent water flowing back into the construction area. Pumps are used to remove any water that seeps through the cofferdams. Diversion tunnels are not always necessary when concrete dams are being built. The river can sometimes be channelled through a large pipe and the dam constructed around it.
Usage of coffer dam
Usage of coffer dam

The construction methods used in building a dam depend on the type of dam being built. The first stage normally involves the removal of loose rock and rubble from the valley walls and river bed. Concrete-faced rock fill dams require a footing or plinth to be constructed around their upstream edge. The plinth is made from concrete and serves as a foundation or connection between the dam and the valley walls and floor. It has an important role in preventing water leakage around the edges of the dam. The area under the plinth is waterproofed by drilling holes and pumping cement grout into cracks in the rock. The thin concrete face on the upstream side of the dam is connected to the plinth via stainless steel and rubber seals called water stops.

Removal of loose rock and rubble from the valley walls and river bed
Removal of loose rock and rubble from the valley walls and river bed
Construction of plinth
Construction of plinth

During dam construction the associated power station and intake works are also being built. When the dam is completed the diversion tunnel is closed and the lake begins to fill. The closure of the diversion tunnel has two phases. During low flow a large re-usable steel gate is lowered across the entrance. The diversion tunnel is then permanently blocked off by the construction of a concrete plug. In some instances, dewatering outlets are built into the plugs so water can be released during an emergency

Refilling the dam after construction
Refilling the dam after construction
Power station near dam
Power station near dam

Canal
A canal is a man-made waterway. Canals are designed and built to withstand enormous water pressure. They have to be watertight so that they won’t leak and they have to be able offer protection from the risk of erosion caused by the flowing water. Canals are built for a variety of uses including irrigation, land drainage, urban water supply, hydroelectric power generation, and transportation of cargo and people. Navigation canals may be shallow facilities designed for barge traffic, or they may be deep enough to accommodate ocean-going ships.
Waterproof linings keep a canal's water from seeping into the ground. The best material is puddle, a mixture of sand, clay, and water that dried to a waterproof state. Modern materials and additives that are more durable include concrete, fly ash, bentonite, bituminous materials, and plastic sheeting.
Locks are usually made of concrete, occasionally lined with steel. If construction of the lock exposes bedrock, the floor need not be lined. The gates are made by welding together steel plates and reinforcement beams. The vertical edges of the gates are fitted with effective sealing materials such as white oak.
Canal
Canal

The Construction of the Canal
Canals are very important hydraulic structures that are used for two important purpose. They are transportation channels, to provide water supply. The types of canals can be described according to the lining. The three main types of canals are earthen canals, rock fill canals and concrete canals.
Planning, surveying and geotechnical work
The first step of canal construction is to preparing the design plan of the canal and surveying works such as traversing, levelling triangulation are done to accomplish design elements. The design elements include alignments, cross-sectional details, location of structures such as locks, towpaths and so on. Geotechnical work includes testing the ground or soil condition with geotechnical analysis such as sieve analysis, shear tests and so on.
Site Clearing
The canal route might pass through vegetation, so in order to construct a clean and suitable construction, site cleaning is done during the route construction and also facilitate access roads and other temporary structures like storage, office, etc.
Excavation or embankment construction
The cuttings and filling are done from the canal design. Excavation is proceeded using suitable equipment and machine, for example, excavators, backhoes, etc. Removed with other earth moving equipment such as loaders and dump trucks. Soil from a nearby source is collected where fillings are predetermined and embankments are constructed and compacted. The canal design is defined as the canal using excavator dimensions and the canal route.
Canal Lining
Canal lining includes two parts which are the actual lining and the water proof layer or subgrade for concrete lining. The first component is geo-membrane to avoid seepage and is placed on the excavated canal course. The layer is optional for concrete canals.

Concrete lining
In order to prevent dry subgrade soil from absorbing water from concrete sprinkling water makes the subgrade wet before concrete lining is formed. According to the structural details, steel rebars are arranged if reinforcement is used. Holding rebars in place when concreting is done by tying and supporting reinforcement.
Concrete placing can be done by manually or using advanced machines. Manual placing involves spreading concrete as if required slope and also includes the use of guide boards or rails to ensure correct elevation and slope. Machines for concreting include slip-form lines, specifically constructed canal pavers, concreting machines with rails, trimmers and etc.
In the other essential stage of concreting, curing has different methods for example, moist plastic sheeting, watering manually or with automated machine, etc. The thickness of concrete lining varies from 0.075 meters to over 0.15 meters depending on the canal size and design.
Subgrade layer
A layer of subgrade is placed with a various type of soil with porosity to a certain degree in order to allow drainage. In order to place subgrade in cutting section, compaction is not compulsory however it is for filled sections. After making subgrade moist and uses machine (rollers), compaction is done. The thickness of subgrade layer ranges is from 2 to 3 feet for the canal floor surface while is around one foot for the canal sides.
Construction of ancillary structures
Ancillary structures involve locks to raise and lower boats for water vehicles, bridges and towpaths for people to walk over or by the canal, weirs to allow a lot of water to flow to another water body, for example, reservoirs and other necessary structures. When every component is completed, the canal is ready to be filled with water from the other sources such as rivers, reservoirs bases on the position of the canal.

For M2 and D1, Arch Dam | Rock fill dam | Arch dams costs are extremely high . | Rock fill dams initial costs are lower | Once it failed , it fails suddenly and destroys everything near it. | A rock fill dam does not fail suddenly. | Construction materials are available and can buy easily | Non-availability of the materials at or near the dam site. | Lower maintenance cost compared to a rock fill dam | Greater maintenance cost as compared to a good concrete dam. | Arch dam requires a strong and sound foundation. | Rock fill dams can be constructed even on compressible foundations. | Build up with strong foundation and can put up to maximum height | Build with less strong foundation and cannot build to a maximum height | A solid gravity dams resist the overturning moments due to all external forces such as water pressure, slit pressure, etc. Such a dam is very strong and rigid and requires least maintenance. These are more suitable in steep valleys where earth dams may tend to slip. In these dams, surplus water may be discharged through the sluices provided in the body of the dam or over spillway built in a suitable location of the dam. Such dams, when built on strong foundation, may be built up to a maximum practical height. A gravity dam does not fail suddenly. Their failure can be predicted well in advance so that loss of life and property may be saved. Their cost of maintenance is least and benefit of cost ratio is highest. These are found more advantageous in the regions of high rainfall and heavy snowfalls. In these dams, sedimentation of the reservoir, may be cleared through deep set sluices. We recommend gravity dam to be used in Myanmar as it has a low cost maintenance and benefit of costs ratio is highest which we need it in our country.

Task 3 (LO 3:3.1 and 3.2)
Construction of marine work concerns with building and repairing piers, docks, boat lifts, harbors and marinas. It is also important to protect such as boats and other vessels, as well as human lives. Marine construction is the kind of field that is responsible for ensuring the structures which are near the area of water are built to last longer.
Marine Work
Marine Work

Marine work includes * designing, developing and constructing ships, boats, machinery and submarines * designing, building and maintaining offshore platforms, oil rigs and pipelines * performing marine surveying as part of research and development of new offshore structures * maintaining and repairing engines, systems and operating instruments.

Caissons A caisson is a water-tight box like structure or a chamber, made of wood, steel, or concrete, usually sunk by excavating within it, for the purpose of gaining access to the bed of a stream and placing the foundations at a prescribed depth and which subsequently forms part of the foundation itself. Caissons are adopted when the depth of water is great and the foundations are to be laid under water. Caissons are generally built on the shore and launched in to the river floated to the site and sunk at the proper position. The shape and size of a caisson depends upon the nature of structure for which it is to be built and the depth up to which it is required to be sunk. Caissons can be broadly classified in the following three different types. (1) Open caisson (2) Box caisson (3) Caisson
Caisson
Pneumatic caisson

Seawall
A structure separating land and water areas. It is designed to prevent coastal erosion and other damage due to wave action and storm surge, such as flooding. Seawalls are normally very massive structures because they are designed to resist the full force of waves and storm surge. In practice, seawalls and revetments are synonyms. A seawall is constructed at the coastline, at the foot of possible cliffs or dunes. A seawall is typically a sloping concrete structure; it can be smooth, stepped-faced or curved-faced. A seawall can also be built as a rubble-mound structure, as a block seawall, steel or wooden structure. The common characteristic is that the structure is designed to withstand severe wave action and storm surge. A rubble-mound revetment often protects the foot of such non-flexible seawalls. A rubble-mound seawall bears a great similarity to a rubble-mound revetment; however, a revetment is often used as a supplement to a seawall or as a stand-alone structure at less exposed locations. An exposed dike, which has been strengthened to resist wave action, is sometimes referred to as a seawall. Seawall
Seawall

Construction of seawall In any construction job, it is important that the survey team carefully examines and surveys the area where the seawall is going to be built. The condition of the land, water, and other surrounding environment are all important factors to consider before any type of construction begins. Additionally, the water level at its highest point is considered. Measurements will also be taken to determine how much of a particular material we will need as well as the size of the project and the machinery required. Examining to survey the area
Examining to survey the area

Once we have taken the necessary measurements and determined the overall length of the seawall that is going to be built, we have to figure out the number of posts or pilings that will be needed. On average, pilings are installed approximately every 6 – 8 feet along the wall.
Determining the number of piling needed
Determining the number of piling needed

At the water’s edge, where the pilings are going to be installed, the area usually needs to be excavated. This means that we will have to remove any debris or materials that will interfere with our construction efforts when attempting to install the new seawall. We also have to excavate and essentially “drill” the pilings into the ground beneath, as these pilings serve as support for the seawall itself. Depending on the environment, time of year, and soil conditions, pilings can be drilled into the ground as little as 4 feet or as much as 6 feet in depth. The variation in these depth measurements is dependent on the height of the seawall overall. Pilings are generally vibrated into the ground using a vibrating machine or a water jet if the machine does not fit on the shoreline. Installing the piles
Installing the piles

This one is pretty self-explanatory, and is also dependent upon the type of seawall that we are installing. Most common type of seawall is a steel seawall. If this is the case, we need to ensure we have enough material such as steel, riprap, sand for backfill, etc. Before the construction begins, each piece of steel is installed individually and carefully so that it is both sturdy and of all the same height. At Seaside Seawalls, a common reason why seawalls fail and they won’t stay in place for very long if they are built without tiebacks and anchors. Tiebacks should be installed into the ground about 6 – 9 feet back from the shoreline, and are usually positioned every 7.5 feet along the seawall for additional support. Anchors, which attach to the tiebacks, are inserted into the ground vertically about every 4 to 5 feet, and also help to hold the seawall Building the seawall
Building the seawall in place.

A cap needs to be welded onto the seawall after it has been constructed. This gives the wall a more “finished” appearance as well as provides additional support to the pilings by keeping them tightly together.

Welding the seawall
Welding the seawall

It is important not to forget to backfill the newly constructed seawall. During any construction project with large machinery, environmental surroundings can sand backfill for seawall become disturbed and not very visually appealing. That is the reason why when we backfill which is usually done with sand. Finally, we grade out the entire area, making sure it is all level, neat and tidy looking. This is usually done by putting top soil and grass seed down, especially if the area became visibly damaged by the machines’ access run.

Backfilling the seawall with sand
Backfilling the seawall with sand

Cofferdam
Cofferdam
Cofferdam
A cofferdam is a structure that retains water and soil that allows the enclosed area to be pumped out and excavated dry. Cofferdams are commonly used for construction of bridge piers and other support structures built within water. Cofferdams walls are usually formed from sheet piles that are supported by walers and internal braces, and cross braces. Cofferdams are typically dismantled after permanent works are completed. Since cofferdams are usually constructed within water, the sheet piles are installed using pre-constructed templates that permit the correct positioning of each sheet pile from a barge.

Construction of cofferdam Firstly, we need to install 12-18” layer of sand on riverbed to maintain water quality and to control turbidity. Installing layer of sand on the river bed
Installing layer of sand on the river bed

Then position the sheet pile template to 71’wide x 110’ long and install a sheet pile. Installation of sheet pile
Installation of sheet pile

Removing water and installing scour protection
Removing water and installing scour protection
Fish and water from inside of the cell are being removed after installing the sheet pile. Then, installing scour protection and place 2’ to 5’ of rock material on riverbed to stabilize sand. In this step, filling the cofferdam with sand gravel is proceeded. Finally, building work platform for mobilize drill rig with install 10’ diameter drilled shaft to drill down to 150’-170’.
Filling the cofferdam with sand gravel and installing drilled shaft
Filling the cofferdam with sand gravel and installing drilled shaft