Large Range Tunnel And Bridge Structure Project Development Essay

Temporary Works are considered any temporary construction used to construct highway, bridge and tunnel related structures but aren't incorporated in to the final structure. Short term works required for construction of everlasting structures include: temporary detour bridge, Work Bridge, falsework, formwork, shoring, cofferdams and short-term retaining structures. Short term Works will be designed according to the guide design technical specs for Short term Works unless specified in any other case herein. Where failing of a temporary structure could have a direct effect on environmental cover, traffic, or open public safety shall be designed and constructed using the standards.

This report is to discuss the role of momentary works and equipment in large size Tunnel and bridge structure project with a good example of a big scale tunnel and bridge task, clarify the impact of non permanent works and equipment on the full total cost of the project. The aim because of this project is to boost the knowledge and understanding on concepts of coming up with and way of measuring of bridge and tunnel works in civil Engineering engineering.

Introduction

Temporary work

Holmes, R (1995) mentioned that On many civil executive projects the cost and design of momentary works forms an extremely high proportion of the full total contract. Therefore care in design and planning is vital. Each temporary composition must be looked at on its merits in relation to the importance of the deal and especially the consequences of failing. If under-design could lead to failing in operating conditions, then the expense of delay, as well as loss the cutting down in design. It is therefore important to create all structure for taking the full in the erection of such structues in bad weather. Guidance in the erection, removal and maintenance of all these structures is paramount.

Where materials are being used more than once, for example as in the case of falsework, they must be inspected to ensure they have not been weakened by their first uses. Second-hand materials should be at the mercy of careful scrutiny before being found in situations where the design was predicated on new materials.

Typical types of non permanent works are:

Ground support, eg cofferdams, timbering, underpinning and shoring.

Access bridges.

Gantries and scaffolding

Trackwork for cranes and trains

Dewatering systems

Specialised issues are handled in detail in following chapters of the reserve.

Builders Seed or equipment

According to the Chudley and Greeno (2006) page 144 the builders plant which range from small hand held electricity tools to bigger pieces of place such as mechanical excavators and tower cranes can be viewed as for use for one or even more of the following reasons:-

Increase production

Reduction in overall development costs.

Carry out activities which cannot be carried out by the original manual methods in the context of economics.

Eliminate heavy manual work thus reducing fatigue and as a consequence increasing efficiency.

Replacing labour where there is a shortage of personnel with the required skills.

Maintain the high benchmarks required particularly in the context of structural executive works.

Bridge and Brief Work

The bridge I decide for this subject is Juscelino Kubitschek Bridge, Brazil. Juscelino Kubitschek was built in 2000-2002, Juscelino Kubitschek is a Arch bridge suspended deck. Corresponding to Holmes, R(2006), stated that "Arch Bridge can supprt better loads-carrying member, the arch is a state of compression throughout. This will make the design suitable for materials which are weak in tension. " The Juscelino bridge

Foundation blocks, of proportions 24 x 40 x 4m, were cast 1. 5m below the water surface for architectural impact. Steel shuttering was installed and the extracted prior to the cement was poured in shallow layers, thus avoiding excessive thermal results and cracking. 1. 2m diameter piles were driven to depths in excess of 50m. Looking back to Figure 7, you will notice that the foundations are much deeper on the right side side than on the departed. The basically poor and extremely variable floor conditions meant that hemorrhoids were driven before desired capacity was reached, often exceeding the expected depths. Horizontal thrusts are transmitted into the foundations due to the rotation of the arches out with their normal plane. To accommodate these residual forces, the pile settings has both vertical and likely piles.

The inclined piers and arch starters were then built on the completed foundation blocks prepared to accept the deck and prefabricated arch areas. The arch starters are made up of a curved and tapered concrete hollow section, as shown in Shape 13.

Two types of deck structure have been used for the JK Bridge: the methodology spans comprises of a profiled steel under holder and concrete slab; whereas the central 720m recognized by the three arches is comprised of a material under holder and orthotropic plate. Short term piers were erected to aid the central portions of the bridge whilst the deck was constructed (Figure 14).

Once the deck substructure had been completed, gigantic metallic truss falsework was erected out of this system, with the temporary piers remaining in place below. A complete of just one 1, 350 lots (approx. 1, 225 tonnes) of metallic was used in auxiliary structures during the bridges construction. Using the falsework set up, the prefabricated metal arch sectors could lifted into place and welded (Physique 15). The ultimate shutting weld was welded completed over night to limit internal stress within the arches anticipated to daily temperature fluctuations.

The stays are made of galvanised material strands, protected by a cover of wax and sheaths of high-density polyethane (HDPE). The stay head shown Number 16 and it is fixed, whilst the upper anchor point is turntable enabling corrections to be made to the stay tensioning. [1]

The inclined cable connection construction has been followed to achieve a better degree of lateral restraint within the deck when subject to wind and transverse vehicular loading. The stays on were installed in phases (Statistics 17- 21) whilst the non permanent helps were still set up, to avoid over stressing and damaging the arch. [8]

An selection of 60 load skin cells and detectors were installed, along with surveying targets, to keep an eye on the strains and deformations within the bridge structure during its development. Several devices remain in place today, collecting data to make a "Dynamic Personal" which is employed to judge bridge performance over its service life, and notify the maintenance program. A large problem encountered during the construction process was the lack of local skilled labour and understanding of steel development. Brazil's metal industry is relatively small, and the subsequent lack of use of the material has left the task drive unskilled in metal development techniques. The nation's

designers likewise have limited knowledge and connection with working with material, so the structural design for the arches was outsourced to Danish consultancy COWI. Architect Alexandre Chan dreams that this iconic bridge will action to encourage a wider use of material within designers, and finally stimulate the development of Brazil's metal industry.

(http://people. bath. ac. uk/cmb27/proceedings/papers/banthorpe_cm_JUSCELINO_KUBITSCHEK. pdf)

Gotthard Bottom Tunnel and temporary work

3. 0 Role of Short term Works in Tunnel Engineering Project.

Tunnel Boring Machine (TBM)

A tunnel boring machine (TBM), which is shown in Body 3. 1, is a machine used to excavate tunnels with a round cross section through a number of soil and rock strata. TBM is a one of momentary works of Tunnel Engineering Project. They are able to bore through hard rock, sand, and almost anything in between. Tunnel diameters can range between a metre (finished with micro-TBMs) to almost 16 metres up to now. Tunnels of less than a metre or so in diameter are usually done using trenchless development methods or horizontal directional drilling alternatively than TBMs.

Tunnel uninteresting machines are used as an alternative to drilling and blasting (D&B) methods in rock and roll and conventional 'side mining' in garden soil. A TBM gets the advantages of limiting the disruption to the surrounding ground and creating a smooth tunnel wall. This significantly reduces the price of coating the tunnel, and makes them suitable to use in intensely urbanized areas. Another edge includes relatively high degree of basic safety against flooding and surface collapse, as the TBM isolates the ground and groundwater from the tunnel proper. Companies are becoming progressively more familiar with the use of EPB type TBMs in UNITED STATES but, however, not in this range. The capability to excavate and install water tight precast concrete segments as the ultimate tunnel lining in one go is another good thing about this technique.

The major downside of the method is the high original capital expenses for the TBM and the long lead time to produce, sip, assemble and test the device, plus the normal inefficiency related to the training curve on startup. TBMs are costly to create, and can be difficult to transport. However, as modern tunnels become longer,

the cost of tunnel boring machines versus drill and blast is in fact less. This is because tunneling with TBMs is a lot more efficient and leads to a shorter project. Another disadvantage is the very large circular tunnel section necessary to provide the traffic lanes, shoulders and sightline, which for vehicular tunnels is not a very reliable use of space. This is also lead to buoyancy issues and the mandatory mitigation when bare minimum cover under the channel is employed. Also, there is a potential for the increased loss of line and level given the tight change radius required and steep decrease accompanied by incline to pass under the channel.

Temporary Control Room in Tunnel Project

All tunneling activities were checked and controlled 24 hours per day by the Temporary Control Room, through mimic or video view of most mobile and fixed equipment, because of a powerful redundant control system able to centralize all numerical/radio/phone communication, vocal and optical alarms. The safe practices desk (PCS) connected by direct mobile to all disaster services (firemen, ambulances, medical center, etc. ). Fixed Equipment Workplace (GTC) is including aesthetic permanent control of ability, ventilation and pumping, connected to 8000 receptors in tunnel and served by 2 calculators, 1 programmable controller and computer sites. Rail Traffic Table (PCT) includes vocal communication with all vehicles and optical monitoring of all tunnel activities on a huge mimic dished up by programmable controllers. A fervent software allowed automatic management of itineraries, location and composition of convoys, paths and catenaries reservations, and even moving stock status. Temporary control room is high first capital costs to create, sip, assemble and test the device, plus the normal inefficiency related to the training curve on startup.

Temporary Electricity Supply

TBM needs a big capacity to excavate tunnels with a round cross section through a number of soil and rock and roll strata. A big temporary power is provided during large scale Tunnel construction job. The high-voltage power of the site is within 90 kV through two 90/20 kV transformers of 36 MVA each. Medium-voltage syndication included nine customized substations, with tunnel power of 20 kV and 3. 2 kV for lamps. A crisis diesel flower was dedicated to TBMs, ventilation, lighting and pumping systems. Short term power is a high impact of cost toward the full total cost of the project.

Conclusion

Bridge temporary work is completely different with Tunnel short-term work. The bridge short-term work is simple compare with the Tunnel temporary work. Bridge short-term work is certainly as falsework, formwork and temporary retaining structure. Both of bridge non permanent works method is low first capital expenditure and the short lead time to create. For Tunnel non permanent work, the high technology engineering is used during tunnel development task. TBM is the high original capital expenditure and the long business lead time to create, sip, assemble and test the machine, plus the normal inefficiency related to the training curve on startup. Large scale tunnel construction tasks spend high non permanent work cost for control room and power supply. At conclusion, total cost of the bridge task is leaner impact compare to the tunnel project.

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