and then sent to proper facilities. However, this causes muddy material to drop from trucks, causing increased litter in cities. Traf?c jam
Since most of the railway constructions are carried out in the most densely
populated areas, city traf?c must be closed and redirected during the construction. In most cases, an entire area must be closed for traf?c. For example, Uskudar square is now closed due to the Marmaray project and most bus stops and piers have been moved to other locations.
With cut and cover constructions, the case becomes even more complicated. In this case, an entire route is closed to traf?c because cut and cover tunnels are
constructed across streets. In order to ensure that machine operation and construction can continue uninterrupted and to minimize the risk of accidents to the people living around the construction zone, streets are either totally closed to traf?c or traf?c is redirected. This causes long-term difficulties. For example, shop owners on closed streets have dif?culties reaching their shops, stocking and transporting their goods and retaining customers. Noise and vibration
For metro excavations, a lot of different machines are used. These machines seriously disturb the environment with their noise and vibrations. In some regions, excavation may be as close as 5–6 m away from inhabited apartment blocks. In such cases, people are disturbed as excavation may take a signi?cant period of time to be completed.
Drilling–blasting may be needed in conventional methods for drilling through hard rock. In this case, no matter how controlled the blasting is, people who are living in the area experience both noise and vibrations. Some become scared, thinking that an earthquake is happening. In blasting areas, the intensity of vibrations is measured. In order to keep them within accepted limits, delayed capsules are used.
In order to minimize vibration and noise caused by machines and to reduce the effects of blasting, working areas are surrounded by fences. Super ?cial blasting shaft rims are covered with a large canvas and fences are covered with wet broadcloths. However, these precautions can only reduce negative effects; they cannot totally eliminate them.
The formation of dust and mud
Depending on the season, both dust and mud disturb the environment. During removal of excavated material, especially muddy material, trucks may pollute the environment despite all precautions taken. Mud that forms around the excavation area may slide down the slope and cover the ground. In this case although roads are frequently cleaned, the environment is still disturbed. Trucks, which travel from dumping areas to areas that are muddy cannot enter traf?c until their wheels and bodies are washed. However, this cannot prevent the truck wheel from dropping mud on the roads while on move.
Interrupted utilities
Interrupted utilities are also one of the most crucial problems facing citizens
during excavation projects due to the fact that telephone, natural gas, electricity, water, and infrastructure lines must be cut off and moved to other areas. During the transfer of these lines, services may remain unavailable for some time. Some institutions will not allow others to do this and carry out operations themselves. With so many
providers conducting individual moves, services may be interrupted for an extended term of time.
Damage to neighbouring buildings
Metro excavations cause deformations around the excavation area. These deformations are continuously checked and efforts are made to keep them under control. However, some deformations may become extensive; including cracks or even collapses of neighbouring buildings. Every metro tunnel excavation in Istanbul causes problems as mentioned earlier. These kinds of problems are more frequent in shallow tunnels. In such cases, although people’s financial losses are compensated, their overall livelihood and way of life is compromised. For example, in a landslip during the ?rst stage of the Istanbul Metro excavation, ?ve people died. Obviously, no amount of money can compensate the death of a person.
Suggestions for remedying environmental problems
Environmental problems that arise during tunnel excavations include traf?c jams, noise, vibrations, dust, mud and deformation of surrounding buildings. Some possible solutions are recommended as listed below:
? In big cities, railway systems are crucial to city transportation. However, a tram should not be considered as a viable railway system due to its low transportation capacity (approximately 1/3 of the metro). At the same time, a tram uses the same route as wheeled transportation devices. Therefore, trams occupy the same space as regular traf?c and do not offer substantial advantages.
? The most crucial problem facing metro excavations is not providing railway lines in a timely manner. Proof of this exists in big cities, including London, Paris, Moscow or Berlin, where metro lines of over 500 km exist. However, in Istanbul, there are only 8 km of metro line. Had the metro been built earlier when the city was not overcrowded, many problems facing the city would not currently exist. Now, of?cials must do their best to reduce troubles that future generations are likely to face.
? Any kind of railway construction carried out above the ground causes serious problems to people living in the area. In addition, these kinds of construction cause both noise and litter. All railway lines are constructed completely underground in many parts of the world. This has two advantages; ?rst, since excavation is carried out underground, it causes minimal interruption in utilities and provides a more
comfortable area to work. Thus, the environment is exposed to very little damage because all operations are carried out underground.
? Before beginning metro excavations, the route must be carefully examined for weaknesses in infrastructures and existing historical buildings. Otherwise, these
elements cause problems, including interruptions in excavation when work must stop until the environment is stabilized. An example of this is that during the second stage of the Taksim–Yenikapi route of the Istanbul Metro, the construction of the Halic Bridge could not be started due to historical ramparts.
? A lack of coordination among related institutions providing utility services is a
major problem. Therefore, founding of an institution that strictly deals with relocating natural gas lines, telephone lines, sewer systems, and electricity will de?nitely
accelerate the transfer of energy lines and avert accidents and inconveniences caused by this lack of coordination.
? In order to increase bene?ts of railway systems both in construction and operational stages, projects must be continuously revised from time to time. This is the main problem facing Istanbul metro excavations. It has taken 110 years to restart metro projects in Istanbul, with the last project, the opening of the Karakoy tunnel,
established in 1876 (Ocak 2004).From this time onward, initiated projects must have been stable and continuous. In 1935, 314,000 passengers were travelling daily. In the 1950s, the total length of tram lines reached 130 km (Kayserilioglu 2001). However, as the trolleybus was introduced in 1961, all tram lines on the European side, and in 1966, all lines on the Anatolian side were removed in order to make way for private vehicles (Kayserilioglu 2001).
Results and discussion
TBM and classic tunnel construction methods are widely used in Istanbul for different purposes, like metro, sewerage and water tunnels. Waste from rock is rarely used as construct ion material as the suitability of the material for this purpose is not well examined. However, it is believed that the muck may be used for some
applications. If this suitability is realized, cost savings may be signi?cant for tunnel construction, where the use of aggregate is a common requirement. A review of standard construction aggregate speci?cations indicates that hard rock TBM waste would be suitable for several construction applications, including pavement and structural concrete (Gertsch et al. 2000). Size distributions of waste materials
produced by tunnel boring machines are less (up to 125mm) than the waste materials produced by using classical construction methods. Muck size distribution is uniform, generally larger (up to 30–40 cm) and can be changed to meet a wide range of
classical construction methods, making the reuse of waste more common. The waste product is used as construction materials. Fifty -seven percent of EW generated
during tunnel excavations result from classical tunnel construction, 33.5% from TBM, while the remaining percentage stems from EPBM and slurry TBM. Different from TBM waste materials generated by EPB and slurry, TBM include mud and chemical materials.
The annual quantity of EW generated in Istanbul is approximately 7.6 million tons. 13.8% of this total is clay and ?ll. The rest is composed of rock. Rock material can be properly used in roadway structures, ?llings, road slopes, for erosion control
and as a sub-base material, as long as it conforms to local standards (TS706, TS1114). Sand and clay have properties appropriate for use as raw materials for industrial use, depending on local standards. More studies should be completed to determine other potential uses for this material. Only 10% of rock material generated during tunnel excavation can be evaluated. A large percentage of soil material, nearly 70,000 m3, can be recycled.
Generally, for any subway construction project, plans for recycling waste
materials should be implemented prior to work commencement. These plans should identify which types of waste will be generated and the methods that will be used to handle, recycle and dispose these materials. Additionally, areas for temporary accumulation or storage should be clearly designated. A waste management plan directs construction activities towards an environmentally friendly process by reducing the amount of used and unused waste materials. Environmental and economic advantages occurring when waste materials are diverted from land?lls include the following (Batayneh et al. 2007): 1. The conservation of raw materials 2. A reduction in the cost of waste disposal 3. An ef?cient use of materials.
EW materials must be kept clean and separate in order for them to be ef?ciently used or recycled. Storage methods should be investigated to prevent material from being lost due to mishandling. In addition, orders for materials should be placed just before work commences. To complete a waste management plan, an estimation of the amount and type of usable and unusable EW materials expected to be generated should be developed. Listing all expected quantities of each type of waste will give an indication of what type of management activities are appropriate for each speci?c waste material. At each stage of excavation, speci?c ways to reduce, reuse or recycle produced EW should be implemented. The ?ow chart in Fig. 2 includes suggestions for an EW management plan.
This paper focuses on EW produced by metro tunnel excavation through hard rock and soil. TBM and classical tunnelling wastes can be successfully used in many construction and speciality applications, including aggregates, erosion control, roadway structures, ?ll, sub-base material and road slopes. In order to minimize
negative effects caused by excavated material both on the environment and on people, it must be reduced at its source. Including forcible decrees through the acceptance of environmental laws would also be useful. Soil and clay material, excavated through the use of EPBM machines, must be reused. It is possible to separate clay and sand, making its reuse possible and minimizing harmful environmental effect.
Waste and recycling management plans should be developed for any
construction project prior to commencement in order to sustain environmental, economic, and social development principles. Waste management is a critical issue facing the construction industry in Istanbul as the industry is one of the biggest generators of pollution. During different excavation projects, construction,
demolitions and domestic activities, Istanbul produces about 14 million tons of solid waste each year, posing major environmental and ecological problems, including the need for a large area of land to be used as storage and disposal facilities. This waste
相关推荐：
loading