The reason why trenchless technology has been applied and attached more and more importance is not only its inherent technical advantages, but also the huge desire brought by social development, which is mainly reflected in: underground crossing is an inevitable requirement of social development. Whether the planning of various sectors is not in place, the coordination is not good, or the infrastructure development needs, the new underground facilities are always increasing, at this time, either excavation or non-excavation, must choose one. As the advantages of trenchless are gradually recognized by people, trenchless technology is becoming more and more mature, and the cost of trenchless construction is decreasing year by year, the application of trenchless is increasing year by year. Underground pipeline is an important part of urban infrastructure, cable pipe, plumbing pipe, heat (dynamic) pipe with underground railway, known as the lifeline of the city, with the development of the society, increasing the length of the underground pipeline, on the other hand, the uneven distribution of pipeline in our country is far lower than the western developed countries, according to 1998 data, tap water and sewage in our country's per capita is only 0.18 m/and 0 respectively. The trenchless technology is being more and more attention and application, has its inherent technical advantages, also has a huge thirst for social development, mainly displays in:
(1) underground crossing is an inevitable requirement of social development. Whether the planning of various sectors is not in place, the coordination is not good, or the infrastructure development needs, the new underground facilities are always increasing, at this time, either excavation or non-excavation, must choose one. As the advantages of trenchless are gradually recognized by people, trenchless technology is becoming more and more mature, and the cost of trenchless construction is decreasing year by year, the application of trenchless is increasing year by year. Underground pipeline is an important part of urban infrastructure, cable pipe, plumbing pipe, heat (dynamic) pipe with underground railway, known as the lifeline of the city, with the development of the society, increasing the length of the underground pipeline, on the other hand, the uneven distribution of pipeline in our country is far lower than the western developed countries, according to 1998 data, tap water and sewage in our country's per capita is only 0.18 m/and 0 lm/person, while Europe on a per capita, sewage is 12 m/people, respectively is per capita value of 66.6 times and 120 times, There is huge room for growth in the trenchless market. During the eleventh five-year plan period, Beijing will need about 2,400 key infrastructure projects, with an investment of about 470 billion yuan. The central city has built a new sewage pipe network of more than 700 kilometers, and plans to upgrade the rainwater and sewage concourse pipe network of 200 kilometers and the water supply pipe network of 500 kilometers. According to the plan of Beijing urban construction planning and research institute, the development of underground space in Beijing in the future will focus on the shallow and sub-shallow underground space, that is, the space above 30 meters below the ground. Subway, underground square, underground street, municipal tunnel (common ditch), large underground gas storage facilities, underground rainwater storage facilities, underground garbage station, underground garage, underground substation and other forms will be built. The construction of communication facilities and functional facilities requires the support of trenchless technology. After the construction of Bridges, buildings and tunnels, it is impossible to excavate and lay pipelines. Although some have surface excavation conditions, but because the pipeline is buried too deep, high underground water level, trenchless will become the preferred method. The latest application of horizontal directional/directional drilling technology is environmental management engineering. Pollutants such as some large waste disposal sites, industrial waste sites, aircraft fuel depots at airports and air force bases, underground fuel storage warehouses, oil refineries, petrol stations and so on infiltrate underground under the influence of rainwater, polluting the groundwater and soil. Horizontal directional/directional drilling technology is used to drill horizontal Wells in contaminated areas, and filtration is laid in them to extract contaminated groundwater and prevent further diffusion of pollutants. In addition, the following treatment methods can be used: air injection and soil gasification material extraction; Recovery of free products (light or heavy insoluble liquids); Biological treatment (injecting culture media to accelerate the decomposition rate of pollutants); Extraction, leaching and chemical stabilization; Soil layer monitoring and sampling. The road network is crisscrossing the ground, the underground facilities are crisscrossing, the urban block function division becomes the conventional engineering construction insurmountable obstacle, has the strong demand to the non-excavation technology. Obstacles that may be crossed in municipal construction include: existing underground municipal pipe network, subway network, highway network, underground space and underground facilities, buildings, rivers, cultural relic protection sites, etc. Traditional construction methods are almost impossible to complete, non - excavation method is duty-bound. The railway network in Beijing now has 114 kilometers of track and 548 kilometers of expressways in the city, which will reach 900 kilometers by 2010. The existing urban expressway network skeleton mileage of 4,073 km, by 2010, the total mileage of highways in Beijing has reached 16,000 km. Beijing municipal pipe network underground has a total length of more than 13000km of various municipal pipelines. In 2004, the total construction area of underground space was 274.4 billion m2, with an average annual increase of about 30 billion m2. These are likely to be obstacles to new construction.
(2) after the construction of Bridges, buildings and tunnels in cities with absolute advantages in trenchless areas where conditions for excavation are not available, it is no longer possible to excavate and lay pipelines. Although some have surface excavation conditions, but because the pipeline is buried too deep, high underground water level, trenchless will become the preferred method. The latest application of horizontal directional/directional drilling technology is environmental management engineering. Pollutants such as some large waste disposal sites, industrial waste sites, aircraft fuel depots at airports and air force bases, underground fuel storage warehouses, oil refineries, petrol stations and so on infiltrate underground under the influence of rainwater, polluting the groundwater and soil. Horizontal directional/directional drilling technology is used to drill horizontal Wells in contaminated areas, and filtration is laid in them to extract contaminated groundwater and prevent further diffusion of pollutants. In addition, the following treatment methods can be used: air injection and soil gasification material extraction; Recovery of free products (light or heavy insoluble liquids); Biological treatment (injecting culture media to accelerate the decomposition rate of pollutants); Extraction, leaching and chemical stabilization; Soil layer monitoring and sampling. The road network is crisscrossing the ground, the underground facilities are crisscrossing, the urban block function division becomes the conventional engineering construction insurmountable obstacle, has the strong demand to the non-excavation technology. Obstacles that may be crossed in municipal construction include: existing underground municipal pipe network, subway network, highway network, underground space and underground facilities, buildings, rivers, cultural relic protection sites, etc. Traditional construction methods are almost impossible to complete, non - excavation method is duty-bound. The railway network in Beijing now has 114 kilometers of track and 548 kilometers of expressways in the city, which will reach 900 kilometers by 2010. The existing urban expressway network skeleton mileage of 4,073 km, by 2010, the total mileage of highways in Beijing has reached 16,000 km. Beijing municipal pipe network underground has a total length of more than 13000km of various municipal pipelines. In 2004, the total construction area of underground space was 274.4 billion m2, with an average annual increase of about 30 billion m2. These are likely to be obstacles to new construction. Trenchless has the competitive advantage of environmental protection and livable. The amount of excavation in a city exceeds a certain proportion, which will inevitably affect traffic and the normal life of citizens. The non-excavation construction does not obstruct the traffic, does not pollute the environment, does not destroy vegetation, does not affect the surrounding buildings, does not affect the normal life and work order of residents. For example, in 2003, Shanghai controlled the total number of excavation projects to no more than 1,000. With the urbanization of the city, the Beijing municipal government has planned Beijing as a livable city and a harmonious society. Especially after the Beijing Olympic Games, people for the construction of daily life interference will be increasingly concerned, the traditional excavation construction will be more and more difficult to be accepted by the public some in a traditional way of municipal engineering construction will seek higher technical content, more and more influence on people's travel and daily life small way of construction, which for the growth of trenchless technology provides good opportunities for development. With the enhancement of people's environmental awareness, the construction of high pollution and strong noise will become a difficult method for the public to accept. If the construction unit takes into account the cost of vegetation restoration after excavation, which will affect the business of commercial shops and the compensation of bus rerunning, the economy of the excavation method will decline day by day. At this time, if the government timely implementation of some mandatory measures, provisions in important sections of Beijing, the core areas must use trenchless method, eliminate the backward technology of trenchless method, the spread of trenchless technology will be a logical thing. (4) a comparative advantage in some engineering excavation trenchless construction with depth increasing when the cost is not too much, and can be reasonable according to the shortest path through the rivers, lakes, railway, highway, city buildings, etc., high construction efficiency, save material consumption, reduce construction cost, so the excavation has a comparative advantage in some projects.
(3) trenchless has environmental protection, livable and other competitive advantages. The amount of excavation in a city exceeds a certain proportion, which will inevitably affect traffic and the normal life of citizens. The non-excavation construction does not obstruct the traffic, does not pollute the environment, does not destroy vegetation, does not affect the surrounding buildings, does not affect the normal life and work order of residents. For example, in 2003, Shanghai controlled the total number of excavation projects to no more than 1,000. With the urbanization of the city, the Beijing municipal government has planned Beijing as a livable city and a harmonious society. Especially after the Beijing Olympic Games, people for the construction of daily life interference will be increasingly concerned, the traditional excavation construction will be more and more difficult to be accepted by the public some in a traditional way of municipal engineering construction will seek higher technical content, more and more influence on people's travel and daily life small way of construction, which for the growth of trenchless technology provides good opportunities for development. With the enhancement of people's environmental awareness, the construction of high pollution and strong noise will become a difficult method for the public to accept. If the construction unit takes into account the cost of vegetation restoration after excavation, which will affect the business of commercial shops and the compensation of bus rerunning, the economy of the excavation method will decline day by day. At this time, if the government timely implementation of some mandatory measures, provisions in important sections of Beijing, the core areas must use trenchless method, eliminate the backward technology of trenchless method, the spread of trenchless technology will be a logical thing.
(4) a comparative advantage in some engineering excavation trenchless construction with depth increasing when the cost is not too much, and can be reasonable according to the shortest path through the rivers, lakes, railway, highway, city buildings, etc., high construction efficiency, save material consumption, reduce construction cost, so the excavation has a comparative advantage in some projects.
