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the big dig

by:Gewinn     2019-08-24
The rapid rail transit project in Basheng Valley will introduce the most powerful karst tunnel construction team in history
Anywhere in the world.
The most challenging part of fast rail transit in Basheng Valley (KVMRT)
The project will be dug 9. 3km twin-
Construction of drilling tunnels and seven subway stations between semandan and tamanmihaja (
Between Maluri and Taman Bukit Ria)
Kuala Lumpur.
Starting near the intersection of Jalan Semantan and Jalan Duta, these tunnels will pass through some of KL\'s busiest and most developed areas before reappearing near Taman Miharjasee kvmrt. com.
My location for the seven subway stations).
The mainstay of the tunnel project will be 10 groups of tunnels-
Boring machine (TBMs).
Contractor MMC for the tunnel section of the project-Gamuda KVMRT (T)
Sdn Bhd has ordered 8 TBMs from Herrenknecht AG, a well-known tunnel equipment specialist in Germany.
Herrenknecht is the same manufacturer of the two TBMs used in manufacturing now-
Completed rainwater management and road tunnels (Smart)
Project located on the edge of downtown Kuala Lumpur.
TBMs excavate rocks and soil with special tools fixed on the head of the front rotary knife;
At the same time, the machine will build a series of concrete rings to lay the tunnel.
These machines are roughly divided into two types: soil pressure balance (EPB)
Type and type of slurry used (
Semi-liquid mixture)shield (SS);
Both types will be used for the KVMRT project, specifically four EPB types and six SS types.
EPB machine supports the palm surface with excavation earth pressure;
The size of the pressure is adjusted by controlling the number of materials dug up by the screw conveyor and the speed of the machine\'s propulsion.
EPB TBMs will be used for more predictable terrain such as the formation of Mount Kenny, which starts with Jalan Semantan, then dock with a more unpredictable karst formation near the Pavilion mall in Bukit Bintang area.
SS type of tunnel-
Boring machines are used in highly variable and unpredictable formations, such as the karstic limestone in the Basheng Valley, which is covered with underground passages, some of which may be filled with water.
If these gaps and water
The filled space will not appear in the pre-
Digging geological surveys, this can be a nasty surprise for anyone digging a tunnel.
Ss tbm can handle this unexpected space as it supports the palm surface by using pressurized mud to ensure ground stability when the cutting head touches the void or cavity.
Slurry shielding is an attemptand-
Tested techniques that allow successful completion of 9. 7km-long Smart.
While the highly variable card drill feature of the Basheng Valley base bed still brings some nasty surprises to the tunnel workers of the smart project, they have gained in dealing with issues using SS TBMsEngineering-
It is wise that the Karst in Kuala Lumpur is classified as \"extreme karst \"(
5 on the scale of 1 to 5)
This means that it has a complex network of underground channels that can move in any direction, steep
Soft cliff
Filled with Rocky heads of valleys and heights.
In fact, Swiss cheese will be a good description of the terrain below KL, and if tunnel workers are not careful, all of these holes and holes will cause sinkholes and ground subsidence during Tunnel construction
When the disturbance of the groundwater level causes the Earth and other debris to move, karst sinkholes and ground subsidence will occur;
This could happen when the tunnel passes through an underground reservoir or water-
Fill the cavity, thus destroying the fine balance of the system.
Another possible consequence is that when the tunnel mud reaches the road surface during the drilling process, the mud is sprayed onto the road surface.
After all these bruises encountered while building Smart, the engineers sat together to brainstorm and do something different for the KVMRT tunnel.
\"We ended up tweaking the components that are common in SS technology to use them in a slightly different way.
\"The final result is the SS boring machine with variable density.
These are arguably the most complex SS machines to be built, \"said contractor tunnel head Donald Robert Hall.
SS TBMs supports the tunnel working surface by relying on the fluid based on sodium bentonite (
Intersection of tool and soil).
Swelling of bentonite when wet;
Its ability to expand several times its weight by absorbing water makes it very useful as a sealant (
Also used as drilling mud for oil and gas wells).
Bentonite makes it possible to create a pressure shield on the palm surface to offset the pressure acting on the ground water and loose soil on the other side of the shield.
However, when a boring machine encounters a cavity, there is no longer any pressure to push back to the Bentonite shield, so the material can be sprayed up to the ground through cracks on the Earth.
In order to offset this instantaneous loss under surface pressure, the concept of variable density TBM was proposed at different times.
The idea is to change the density of bentonite by adjusting the thickness of the limestone powder mixture and controlling the propulsion speed of the TBM.
For MRT projects, bentonite will be mixed with limestone powder to produce slurry that can be more easily controlled with compressed air with density and viscosity.
However, this is the first time a variable density machine has been assembled by components already used elsewhere;
This is also the first time they have used existing technologies in different ways.
Engineers and Herrenknecht conducted various trials with the help of the University of Bohong, Germany, to obtain the best proportion of bentonite and limestone powder, and determine the behavior of the mixture under the conditions expected during the actual tunnel excavation process.
\"Variable Density is fairly good in theory, but it is not easy to achieve in practice,\" said Sati Boghal, project director of the tunnel section of the KVMRT project.
He pointed out whether it is important that the boring machine operators have a good \"feel\" about the machine so that they can use very good-tuned controls.
It is necessary to use these innovative TBMs, as the tunnels will pass through some of the highest levels of tunnels in the country
Located in the urbanizing area at the top of extreme karst, even detailed geotechnical investigations do not provide complete underground conditions.
\"In the Casti terrain, you can drill a hole per meter, but still not sure what is between the two,\" said Satti . \".
\"This is the difficulty we face.
The variable density machine is your best tool, as it is designed to overcome the problem of falling groundwater levels, which have been identified as the root cause of the sinkhole.
\"In theory, the use of variable density SS TBMs should significantly reduce soil settling or sinkholes on the road surface compared to smart buildings, although, thankfully, most of the tunnel routes are through sparsely populated areas, but it is true that quite a few sinkholes have been seen throughout the area. Other values-
Another feature of the six variable density SS TBMs is that they can be converted into another TBMs, EPB (
Soil pressure balance)
Type, if required, for example when crossing the mixing stage or the Kenney mountain layer.
Let them pay more.
Effective: This conversion can be done without dragging the machine back to the surface.
\"It will take two days for the changes,\" said Satti, who has worked with the railway department for more than 30 years, and can boast of making a difference in the construction of the Kaohsiung MRT and Taipei. Kaohsiung high-
There are high-speed trains in Taiwan.
The tunnel contractor is pleased that it will have a height-
Experienced underground teamrelated work (
Including Hall, Gus krados and a Malaysian team who have been involved in smart projects and other foreign tunnel projects).
\"This will be the most powerful karst tunnel team assembled anywhere in the world,\" said Sati matter . \"of-factly.
Surprisingly, the construction of the seven subway stations will not be more challenging than the tunnel part due to the large amount of deep excavation involved;
Also, there is not much room for maneuver on and below these stations.
\"In fact, when you do deep excavation, you are more likely to get soil settling in the surrounding area.
\"The tunnel part is not so much a problem, it is better to have these technically advanced mitigation measures and we are very confident to move forward,\" Sati said . \".
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