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1. In the case of small amount of demolition, the project cost of this method is low and the speed is fast. However, e to the large traffic interference, it is not easy to implement in urban areas. It can only be used in open excavation in suburb and open area. When the soil stability needs, the supporting pile or diaphragm wall should be used for foundation pit support; When the engineering structure is in the position of groundwater interference, it is necessary to take drainage measures
the construction technology of open cut tunnel is relatively simple, the force is clear, and the operation is convenient, but it needs to do a good job in the demolition or reinforcement of underground pipelines, surface traffic diversion, environmental protection and foundation pit safety and stability. When the foundation pit stonework needs blasting, the blasting scheme must be prepared in advance and submitted to the competent department for approval before implementation
2: top down cover excavation method
2: top down cover excavation method is a kind of cover excavation method. In this method, the retaining wall, supporting column and roof of the tunnel (or station) are built first, and then the single-layer or multi-layer underground tunnel (or station) structure is constructed by using the top-down top-down top-down method by using the entrances and exits, ventilation cts or separate shafts. This method is between the open cut method and the concealed cut method. Except for the open cut construction of the roof, the other structures are constructed by the concealed cut construction. This method is especially suitable for urban areas with dense population and heavy traffic
most of the earthwork in this method is excavated in the tunnel within the top cover and retaining wall structure, which is suitable for soft soil stratum, and the ground water is stable below the base elevation of 0.5m, otherwise, precipitation measures are needed
the top-down construction method is generally divided into two stages: the ground construction stage: enclosure wall, middle column and roof construction; Tunnel construction stage - earth excavation, structure, decoration and equipment installation. Earthwork and equipment are transported by shaft. In the ground construction stage, the construction has interference to the ground traffic, people's life and underground pipelines, which should be completed quickly and carefully. Roof, retaining wall and column are part of the main structure ring construction and operation; The floor slab completed ring construction is an integral part of the overall structure to help the side wall maintain stability ring construction and operation. When it is necessary to stabilize the side wall, temporary horizontal bracing should be added above and below the floor slab; The bottom plate is the last part of the whole main structure, and it is an important link to realize the structural closure. It is of great significance to ensure the safety and stability of the tunnel (station) construction
3: shotcrete and anchor excavation method
3: shotcrete and anchor excavation method is a stable manual excavation method, which supports while excavating, restricts the displacement of surrounding rock, makes the surrounding rock and supporting structure form a supporting ring together. When the tunnel is excavated in the soil layer and unstable rock mass, the working face is disturbed. In order to prolong the stability time of surrounding rock, it is necessary to take advance pre support or reinforcement measures (such as grouting, freezing, etc.) before excavation. The strata and surface conditions along the tunnel excavation vary a lot, so it is very important to master the engineering geological and hydrological data in detail, formulate the excavation technology and scheme in detail, and ensure the stability of surrounding rock and timely closure of initial support in the excavation process. In this method, the soil and equipment are usually transported through the shaft. Steel arch (arch section) and shotcrete are generally used in the initial supporting structure. The whole construction process is mainly manual operation, so it must be ensured that there is no water in the tunnel ring the construction period
the construction of shotcrete anchor excavation method is always in the dynamic process of construction and replacement of excavation soil and tunnel structure, and the tunnel surrounding rock is always in the alternating process of stability and instability. In order to ensure the stability of tunnel surrounding rock in the construction process, the monitoring and measurement method must be used to monitor the state of surrounding rock and supporting structure in real time, and feedback information in time to guide the safe construction
in order to ensure the smooth tunneling and the stability of surrounding rock, various auxiliary construction methods are often needed in the construction. When drilling and blasting excavation is needed, smooth blasting should be used for hard rock and presplitting blasting should be used for soft rock. Before blasting, blasting design should be carried out, test and correction should be carried out according to specifications, and blasting scheme can be implemented after being submitted to public security department for approval
shotcrete anchor excavation method is also commonly used in subway station construction
4: shield method
4: the method of using shield machine to carry out tunnel excavation is called shield tunneling method. The shield machine has the functions of excavation, support, slag discharge and tunnel lining segment assembly. The common types of shield machines are open type, grid type, earth pressure balance type, slurry balance type and air pressure type. All kinds of shield machines have a certain scope of application. According to the control requirements of tunnel outer diameter, buried depth, geology, underground pipelines and structures, ground environment, stability of excavation face and control value of ground heave and subsidence, the equipment selection should be carried out after technical and economic comparison, so as to make the construction quality high, cost low and safety
the shield machine is protected by its shield shell, which not only supports the surrounding soil, but also protects the safety of machines, equipment and personnel in the shell. In the stratum without underground water, open shield can be used to excavate the front soil by hand or semi mechanical method; The mesh is set on the breast board of the shield machine. When the shield machine is pushed in by the jack, the soil on the front side is squeezed into the inner side of the breast board through the mesh, and the soil is transported away by the apron conveyor; The earth pressure balance and slurry balance shield machines belong to the closed chest mechanized shield machines, which are suitable for the strata with underground water and strict requirements for surface heave. The head of the shield machine has a cutter head, and the soil is cut into the soil tank, and the screw conveyor is used in the machine to discharge the soil (the slurry shield machine uses a mixer to fully mix the soil and water in the soil tank into a flow state, which is transported and discharged by a pump)
the mping speed and driving speed should be organically coordinated to maintain a certain soil pressure on the excavation face, maintain soil stability, and achieve the purpose of controlling the stability of surrounding rock and surface
in the process of tunneling, segment assembly equipment assembles segments ring by ring to form tunnel lining. There are water sealing strips between the segments, which can form the water sealing function ring installation. There are grouting holes in the head of the machine, which can be used for filling in the void and grouting to limit the ground settlement. Grouting holes can be left in the segment for secondary grouting. In order to ensure the earth pressure always exists in the soil of the engine head, there are grouting systems to improve the plasticity of some soils in the soil tanks or water or foam.
different shield machines are different in equipment, technology and applicable conditions, but the basic tunneling principles (maintaining soil stability, human-machine safety, environmental safety, etc.) are the same. Therefore, in shield tunnel construction, measurement and monitoring work is still an indispensable part
the above answers are sorted out and released by the construction platform
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extended information:
with the rising price of bitcoin, domestic virtual currency has become increasingly active. Cai Lei, a senior executive of a financial institution in Beijing, said that some "Shanzhai currencies" have declared that they are not within the scope of the regulatory authorities, the mainstream virtual currency has declined, and their own virtual currency has ushered in development opportunities
Zhao Shouguo, a professor at the school of economics and management of Northwestern University, believes that the closure of mainstream virtual currency exchanges such as bitcoin has brought opportunities to many "counterfeit currencies". Reporters found that in QQ and other social software input "coin" word, found a large number of "play guest coin", "radar coin" and other named groups. In the forum post bar, "Yite coin", "red shell coin", "HBB environmental protection coin" and other virtual coins are various
Noise, st, soil, heat, high-intensity vibration and impact, all of which are the most common working environment in mining and tunnel engineering? It has to be said that in the past, the way of excavating tunnels was somewhat & quot; Rough & quot;, A tunnel is blasted by blasting. There are many disadvantages in this way. Not only is the mountain blasted irregular, but also people need to deal with the rockfall frequently. If it is not handled properly, a series of casualties may be caused by the explosion. In this way, it is very dangerous indeed. In the 1990s, in order to build the Xikang highway, when the tunnel was built, China has imported two shield machines from Germany, each with a price of US $100 million. In order to prevent leakage of secrets, Germany does not allow to see them while doing maintenance and service
the shield method is generally used in subway construction. One artifact that this method can't do without is the one mentioned above; Shield machine;, It's a magic giant, weighing several hundred tons. It's an expert in digging the subway. Maybe my friends can't understand the shield machine technology. It uses a relatively large drilling machine, which cuts the plane through the cutter head and assembles the segments alternately. It moves forward under the push of the hydraulic jack, because there is a sensor on the cutter head, If the temperature of the machine is too high, it will send a warning signal to the center, which greatly improves the safety. At present, the largest shield machine in the world is located in Japan; Bertha & quot;, The diameter is 17.5 meters and the length is about 110 meters. The most amazing thing is its weight, which is 7000 tons. It can be seen that the shield machine is huge
if Newton's discovery of gravitation can be attributed to an apple, then the original inspiration for the invention of shield machine came from an insect. In the early 18th century, a French engineer discovered that when a kind of moth (ship maggot) drilled holes in a ship's board, it would secrete liquid and apply it on the wall of the hole to form a hard protective shell to resist the expansion of the board after it was wet, so as to prevent it from being flattened, This engineer discovered the principle of shield tunneling and registered a patent in the UK. Now the shield machine integrates optical, mechanical, electrical, hydraulic, sensing and information technology. It can automatically complete many functions, such as excavation, cutting, transporting soil ballast, assembling tunnel lining, measuring and guiding deviation correction, etc. it has the body shape of a snake and the speed of a snail
however, digging through mountains is like chopping melons and cutting vegetables to it. Some people say that it is precisely because of it that subway excavation can be so smooth. China's subway mileage is already the first in the world, which is a proud thing. If you are curious about subway excavation, you might as well go to Guangzhou subway Museum, where there is a lot about the history and evolution of subway, As well as the world's subway signs, there are 1:1 shield machine model, you can really see the process of subway excavation
generally speaking, the weight of this kind of machine is about 500 tons, and its length is 80 meters. During each operation, it is necessary to dig the foundation pit at the beginning and end of the tunnel, and then the machine will work according to the aspects of the tunnel, so as to move forward. When excavating the soil, it can also stick the ring segments of the concrete, The powerful outer layer of this machine can also play a supporting role for the tunnel that has not been built well, and it is more safe. It will not affect the usually crowded road, nor will it affect many pipelines in the operation. It has the advantages of high automation, fast speed and high efficiency, and also saves a lot of manpower, And the operation of the machine is completely unaffected by the weather
do you know? On September 7, the shield machine of water resources allocation project in Pearl River Delta was launched; Yuehai 2 & quot; The successful launch of the work well in the A2 bid project marks the official opening of the landmark project in Guangdong, Hong Kong, Macao and Dawan District, one of the 172 major water conservation and water supply projects deployed by the State Council; Crossing mountains and rivers; In the new stage of construction, it is reported that Yuehai No.2 shield machine will undertake the tunneling task of 3508m
The Yuehai No.2 shield machine has a total length of 105 meters, a total weight of 680 tons, a total installed power of 2900 kW and a cutter head diameter of 6.32 meters, which is equivalent to two floors, It can not only face the challenge that the shield is buried as deep as 120 meters, but also gnaw down the weakly weathered granite gneiss with the maximum strength of 160 MPa; Hard bone;, At the same time, it can also overcome the complex hydrogeological conditions of Xijiang River; The artifact of making holes;, Isn't that great
bus line: Metro Line 1 → Metro Line 13 → No.121, the whole journey is about 19.3km
1. Walk about 730m from Shanghai Dimei shopping center to people's Square Station
2. Take Metro Line 1, pass 2 stops, and then reach Hanzhong Road Station
3. Walk about 210m, then transfer to Metro Line 13
4. Take Metro Line 13, pass 11 stops, Arrive at Jinyun Road Station
5, walk about 740 meters, arrive at Jinyuan 1st Road Jinsha Jiangxi Road Station
6, take bus 121, pass 1 stop, arrive at Huazhuang Road (Huazhuang Village) station
7, walk about 240 meters, arrive at Vienna International Hotel Shanghai
shield machine, fully known as shield tunnel boring machine, is a kind of special engineering machinery for tunnel excavation. Modern shield machine has the functions of cutting soil and rock, transporting soil ballast and gravel, assembling tunnel lining, measuring and guiding deviation correction, etc., forming a spacious underground cement tunnel where the shield machine passes
the body of shield machine is welded by thick steel plate, which is used to bear the pressure of surrounding soil layer and create a working face for excavating tunnel. Its front cut is equipped with a large slow rotating disc, which is equipped with many fast rotating cutters. Its shape is not like a drill, but more like the cutter head of a Philips razor. In the tail of the shield machine, the tunnel is assembled by using the tunnel lining segment (a kind of prefabricated part to build the tunnel wall), and concrete is poured into the gap between the lining and the shaft wall to strengthen the tunnel and prevent the infiltration of groundwater. When the shield machine reaches a certain distance, the jacking force can be borne by the friction between the tunnel lining and the stratum. In the cement tunnel formed by shield tunneling, two rails are immediately laid, one for transporting soil slag and gravel, and the other for transporting lining segments and concrete
when there is loose soil or groundwater in front of the shield machine, the shield machine uses refrigeration technology to freeze the loose soil or groundwater in front of the cutterhead, so as to break the ice. Therefore, the shield machine is also suitable for excavating river crossing or subsea tunnels
the process of excavating the subway tunnel is as follows: first, dig a large deep pit at the platform, install the shield machine in the deep pit, and then start to drill. In order to speed up the process of subway civil construction, two shield machines can be used to face each other between two platforms to carry out excavation
shield machine can improve the underground excavation efficiency of subway by 8 to 10 times, and in the process of construction, there is no need for large-scale demolition on the ground, no traffic interruption, no construction noise, no ground settlement, and no impact on the normal life of residents. The large shield machine has high added value technology and complex manufacturing process. In the world, only a few enterprises in Europe, America and Japan can develop and proce it, and the price of each shield machine is about 100 million yuan. Now there are domestic shield machines, each of which costs about 3000 yuan, greatly recing the cost of subway construction
by the way, at present, the distance between the subway tunnel and the ground is generally 18 meters, while the pile length of modern buildings with more than 20 floors is more than 18 meters. In order to avoid the pile of these high-rise buildings, the subway tunnel is usually built under the streets of the city. But the street turns at 900, and the subway train can't turn at 9O0, that is, it needs an R (i.e. radian). Therefore, some high-rise buildings need to be demolished at the corner of the subway, which greatly increases the cost of the subway.