In 1960s and 1970s, the development and utilization mode of underground space began to occupy a dominant position. Since the 1970s, with the rapid development of cities, more and more cities have experienced serious "urban diseases" such as traffic congestion, increased pollution, shortage of space resources and deterioration of urban environment. In the 1980s, the International Tunnel Association put forward the slogan of "vigorously developing and utilizing underground space to create a new cave age for mankind". 1982, the United Nations Committee on Natural Resources officially listed underground space as "potential and rich natural resources", and underground space is considered as the last future development field alongside the universe and the ocean. 199 1 The International Conference on Urban Underground Space adopted the Tokyo Declaration, proposing that "2 1 century is the century of human exploitation and utilization of underground space". In 2002, the theme of the underground space academic conference held in Turin, Italy was "Urban underground space as a resource". It can be seen that urban underground space, as a natural resource, has been paid more and more attention and will be gradually developed and utilized.
6.2. 1 Investigation on the Utilization of Urban Underground Space
With the rapid development of urban space, the scale of the city began to radiate from the center to the surrounding towns and villages. In the urban core area, in order to meet the requirements of highly concentrated development of its commercial functional areas, the utilization of urban underground space has become one of the important means to improve the economy of land use.
The so-called "underground space utilization" is the utilization of urban geological bodies. Urban geological body is the space for urban underground development and the "carrier" of underground space resources. It belongs to land resources and is an extension of urban land resources. On the one hand, due to the complexity and diversity of lithology, lithofacies, genesis, structure and structure of urban geological bodies, the rock (soil) strength or anti-interference ability of urban geological bodies is quite different, not only the geological environment conditions are complex, but also there are some sensitive areas with fragile geological environment or areas unsuitable for development; On the other hand, the development and utilization of urban geological bodies destroy the original ecological and environmental geological balance, and also have a certain impact on surface engineering or existing underground engineering, causing environmental geological problems or geological disasters.
(1) development process
Since 1863, the world's first subway was built in London, England, the development of underground space abroad has gone through a long time. Since the 1920s, the process of urbanization has been accelerated all over the world, and problems such as urban land shortage, traffic congestion, backward infrastructure and environmental degradation have become increasingly prominent. In order to solve these problems, some developed countries began to use underground space on a large scale, and countries and regions such as Europe, America and Japan developed and utilized it earlier. Among them, European countries make good use of underground space, and making full use of underground space has the advantages of constant temperature and humidity, heat insulation, shading, air tightness, concealment and safety. They have extensively built intersections, subways, shopping centers and warehouses. In recent years, they have also built underground comprehensive service areas, underground power plants, nuclear power plants and garbage disposal plants.
Compared with foreign countries, China started late, but in recent years, it has a good development momentum, which is not only rapid in development, but also large in construction scale. The utilization of underground space in China began at the earliest in the northwest Loess Plateau. Up to now, more than 40 million people have lived in cave buildings that have lasted for thousands of years, and a simple cylindrical arch underground grain depot has been built in the loess layer. Urban underground space in China is mainly concentrated in underground traffic, underground shopping malls and civil air defense. Beijing and Tianjin were the first cities in China to build underground railways, which began in the 1970s. Shanghai and Guangzhou followed closely, both of which were completed and put into operation in the 20th century. Then Nanjing and Shenzhen were completed and put into operation at the beginning of 2 1 century; Shenyang, Chengdu, Hangzhou, Harbin and other cities are under construction; Xi, Suzhou, Xiamen, Qingdao and other cities have established projects; Cities such as Ningbo, Nanchang, Jinan and Fuzhou are also under planning. The whole country has set off an upsurge in the construction of subways, which has triggered a new upsurge in the utilization of urban underground space.
(2) Characteristics and advantages of underground space
Underground space has some incomparable characteristics and advantages over above-ground space, such as good earthquake resistance, stability, concealment, protection and sound insulation, which can meet some special needs of cities. The main advantages are as follows:
1) The underground building has good seismic performance, the earth pressure is absolutely higher than the air pressure, and the damage resistance is stronger than that of the ground building, which can effectively prevent the invasion of various natural disasters, such as typhoon, lightning, hail and other natural disasters will not directly affect the underground building at all. For example, during the Tangshan 1976 earthquake, most underground projects in Tangshan were intact after the earthquake, and there were no casualties in civil air defense projects, which greatly reduced the earthquake damage.
2) Subway, various underground passages and underground parking lots can effectively alleviate the urban traffic tension and divert the crowded traffic and crowds on the ground; At the same time, underground traffic is safe, reliable, convenient and fast, which reduces traffic accidents.
3) There is no natural noise in the underground space. Introducing projects with "three wastes", high vibration and noise, dangerous goods, constant temperature and humidity and many public facilities into the underground can occupy less land, beautify the environment and maintain the urban ecological balance.
4) The development of underground space is conducive to reducing urban pollution, avoiding mutual interference between production and life, loosening ground space, increasing green space and improving environmental quality. The underground temperature is almost constant, so the heating and cooling load is greatly reduced. In summer, cold air can be pumped out to cool the ground, and its energy consumption can be reduced by more than 60%, saving energy.
5) The food stored underground not only has low cost, low loss and long service life, but also can be kept fresh for a long time without destroying its internal nutritional structure after scientific treatment, which is beneficial to people's health.
6) Underground warehouses are ideal safe places, especially vaults, oil depots and warehouses for highly toxic and dangerous goods. In case of an accident, it is easy to control and difficult to spread, and it can be foolproof.
7) Underground buildings are easy to maintain, not easily disturbed by natural disasters and climate disasters, with long service life and great development potential, which is an indispensable new development and utilization direction for eco-city construction.
(3) Development significance
1) For the development and utilization of urban underground space, putting infrastructure and related buildings underground not only saves the ground space, but also brings huge business opportunities and forms corresponding economic benefits.
2) Take the road of three-dimensional development of urban space, effectively improve the theoretical capacity of urban space, solve the contradiction of insufficient urban land, adjust the organizational structure and form of urban space, change the extensive development of urban space into intensive development, improve the operational efficiency of urban space, and ensure the good operation of urban functions.
3) The development and utilization of underground space is conducive to protecting the urban environment, purifying the air, protecting water sources, reducing noise, improving the quality of urban sanitation, increasing greening and public space, reducing the floor area ratio and reducing the total amount of buildings.
4) The development of underground space will continuously improve the city's disaster prevention and resilience. Building underground streets can evacuate a large number of people, and building underground warehouses can store food, materials and energy.
5) Underground buildings not only play an important role in preventing natural disasters, but also play an important role in preventing nuclear weapons and conventional weapons even in wartime.
(4) Utilization mode
Through the comparative study of Shanghai, Wuhan, Guangzhou, Changsha, Nanjing, Shijiazhuang, Montreal, Kansas, St. Petersburg and other cities, we can find that the utilization of underground space resources in cities is multifaceted, which can be summarized as follows (Table 6. 1):
Table 6. 1 Utilization mode of underground space resources
1) Underground pipeline construction of urban infrastructure, including water supply, rainwater, sewage, gas, electricity, telecommunications, etc.
2) Construction of underground traffic and commercial facilities, underground roads, underground passages, subways and underground shopping malls. It is the first choice for the development and utilization of urban underground space, with early development and rapid development.
3) Build energy facilities, such as power plants and strategic energy reserves (natural gas and oil), and use deep underground dry-hot rocks to generate electricity.
4) Development and construction of water conservancy facilities such as underground reservoirs, artificial rivers and large regulating ponds.
5) Construction of underground cultural centers, sports facilities, underground research (experiment) facilities, underground entertainment facilities, underground factories, underground disaster prevention facilities, emergency water supply pools, reservoirs, shelters (civil air defense), fire exits and other facilities.
(5) Planning principles
Underground space is a non-renewable resource, which can neither be increased nor created, and will decrease with the use of human beings. Therefore, rational planning and orderly development should be carried out when using underground space resources. Underground space resources utilization planning should comprehensively lay out and develop underground space, coordinate underground and aboveground, underground and underground construction activities, and provide technical basis for the development and construction of urban underground space. Planning needs to follow the following principles:
1) the principle of combining development with protection: when developing underground space resources, pay attention to the protection of resources and consider the needs of urban future development.
2) The principle of combining up and down: fully consider the relationship between the ground and underground, give full play to the advantages and characteristics of underground space, and make underground space and above-ground space form a whole to serve the city together.
3) The principle of long-term consideration, short-term implementation and phased implementation: we should not only proceed from a strategic height, face the future, but also start with solving the existing outstanding contradictions in the city, so that the goal can adapt to the current situation of economic strength step by step.
4) Comprehensive benefit principle: determine the function and layout of underground space, and implement encouragement and preferential policies for the development of underground space.
5) Rational design principle of underground buildings: The underground space is grounded, so that people can fully contact with nature, feel the sunshine, plants and air underground, eliminate people's strangeness and oppression of underground space, and enhance the sense of guidance of underground space.
6) Disaster prevention design is the most important principle.
6.2.2 Utilization of underground space around Jiaozhou Bay
(1) Economic conditions of underground space utilization
The development and utilization of underground space is related to the economic development level of the city. The practice in developed countries has proved that only when the economy develops to a certain extent (it is generally believed that the per capita GDP is 500 dollars) can the conditions for the development and utilization of underground space be met: when the per capita GDP is above 500 dollars, underground rail transit becomes the need of urban development; When the per capita GDP reaches 500 ~ 2000 USD, the subway will be widely used. When the per capita GDP exceeds 2000 dollars, the development and utilization of urban subway will develop to a higher level.
The per capita GDP around Jiaozhou Bay has already exceeded 500 dollars, which has the economic conditions for developing underground space. However, the development and utilization of underground space should be based on the actual needs of development and its own economic strength, rational planning and orderly development.
(2) unified planning and management
Strengthen the unified planning and management of underground space development and utilization around Jiaozhou Bay, and realize the organic combination of urban underground space development and utilization planning and urban disaster prevention and mitigation construction.
(3) Three-dimensional comprehensive development view
Determine the three-dimensional concept of comprehensive development and utilization, and build underground facilities into a multi-purpose, multi-functional and multi-functional complex. To transform existing underground facilities, all single projects that can be transformed should increase their functions and uses, such as air-raid shelters that can be transformed into facilities that usually benefit; New underground facilities should be built into multifunctional complexes.