In the future development of urban space, besides the vast sky, there is also the profound underground space, and of course, in the farther future, the mysterious outer space. But today, we are talking about urban underground space.
The development and utilization of underground space should be coordinated with urban development strategies, combined with the actual situation of urban development, scientifically planned, and the scale, timing, and development mode of underground space planning and construction should be reasonably determined to steadily advance underground space construction. The development and utilization of urban underground space should be based on and in accordance with underground space planning, and carried out strictly in accordance with the plan.
First, classification
According to the reasons for formation, it can be divided into two types: natural underground space and artificial underground space. According to the construction form, it can be divided into underground buildings in rock and soil and underground buildings in soft soil. Underground buildings in soft soil can be further divided into single-built and attached-built according to their relationship with ground space.
According to the depth of resource development, it can be divided into three types: shallow space, middle space, and deep space. Shallow space: 0~-30m depth, commercial, entertainment, business space, etc. Middle space: -30m~-100m depth, underground transportation, public facilities. Deep space: below -100m, rapid underground transportation, dangerous goods storage, cold storage, and oil depots, etc.
According to functional use: commercial space, entertainment space, traffic space, disaster prevention space, logistics space, storage space, residential space, business space, production space.
Then, layout
Corresponding mode of upper and lower space functions and environment, urban center underground complex mode, single-function mode of underground commercial street, three-dimensional square mode, considerate hub station mode, underground traffic engineering mode, dependent underground traffic mode.
Planning principles
The principle of combining development and utilization with protection; the principle of adapting development space functions to the characteristics of underground space; the principle of corresponding functions of upper and lower spaces; the principle of coordination between development plans; establishing urban lifeline systems to enhance urban carrying capacity; the principle of spatial structure meeting the requirements of combining peacetime and wartime.
Overall development, orderly utilization
The development and utilization of underground space should adhere to the principles of overall arrangement, comprehensive development, and rational utilization. Adhere to the policy of combining peacetime and wartime, and coordinating underground and aboveground, encourage vertical layered three-dimensional comprehensive development and horizontal connected development of related spaces, and improve the integrity and systematicness of urban underground space development and utilization.
Vertical planning methods
Design contour method: Determine the red line elevation around the land, the design elevation of main nodes, and connect them into design contours of large terrain. When connecting, try to pay attention to repeating with natural contours of the same height. After all design contours are marked, the earthwork balance should be estimated to check the economic rationality of vertical planning.
Elevation arrow method: According to the principles of vertical planning and design, determine the ground elevation of various buildings and structures in the area, the elevation of road intersections, slope change points, and the elevation of terrain control points in the area, mark them on the vertical planning map of the residential area, and use arrows to indicate the drainage direction of various types of land in the area. This method has a small workload for planning and design, faster drawing production, and is easy to change and modify. It is a commonly used method for general vertical design of residential areas, but it is relatively rough, requires sufficient experience to determine elevations, and some parts of the elevation are not clear, with poor accuracy. It is only suitable for situations with relatively simple terrain changes.
Vertical and horizontal section method: This method is mostly used in areas with relatively complex terrain. Its advantage is that it provides a three-dimensional image concept of the original terrain of the planned design area, making it easy to consider terrain and transformation.
Avoid misunderstandings in structural design
(1) Hidden beams used as floor beams: loads cannot be transmitted in the imagined way, that is, the transmission mode of floor load → slab → hidden beam → column is almost impossible.
(2) Frame structures form de facto hinges. The most common is that the beam stiffness is much larger than the column, making the column's constraint on the beam weak, forming a de facto hinge, reducing the number of statically indeterminate times, which is unfavorable for seismic resistance and difficult to form "strong column, weak beam".
(3) The load-bearing reinforcement of the slab wall is placed inside the distribution reinforcement.
(4) Beams are supported on frame beams close to columns. Due to the support position close to the column, the rotation of the frame beam is constrained. When the load of the beam supported on it is large, a large torque will be generated, making the reinforcement of the frame beam difficult.
(5) Slab reinforcement does not extend above the load-bearing reinforcement of the up-turned beam. The most common is that there is a closing crossbeam at the top slab at the entrance of the passage, and its bottom slopes downward along the slab, forming an irregular beam.
(6) Subway stations do not consider openings in the middle slab. Because the impact of openings is difficult to calculate, and also because some people do not take the impact of openings seriously, it is ignored in calculations.
Ecological priority, public interest priority
Urban underground space planning and construction should be based on the ecological bottom line and specific requirements of ecological protection, carry out rational development and utilization, and strictly control underground space unsuitable for development; at the same time, priority should be given to municipal infrastructure, underground transportation, civil air defense projects, emergency disaster prevention facilities, and take into account the needs of optimal urban operation and adjacent space development, ensuring the safety of people's lives and property and the legitimate rights and interests of underground space rights holders.
Terrain and environmental protection measures
① Try to maintain the original state of plants and trees within and outside the construction boundaries specified in the contract; when cutting trees and other economic plants, consent from the owner and proprietor must be obtained in advance, and cutting beyond the scope is strictly prohibited.
② Cultivated land within the temporary land use scope shall be restored by measures after construction. Other exposed surfaces shall be planted with grass or trees for greening.
③ Create a good environment. Set up sufficient temporary sanitation facilities at the construction site and living area, carry out sanitation cleaning frequently, and plant flowers and trees around the living area to beautify the living environment.
④ Harmful substances (such as fuel, waste, garbage, etc.) shall be incinerated or treated by other measures and then transported to designated locations for burial to prevent damage to animals and plants.
Water environment protection measures
① Construction wastewater and domestic sewage shall be treated according to relevant requirements and shall not be directly discharged into farmland, rivers, and channels.
② Water for cleaning aggregates and other construction wastewater shall be filtered and precipitated before discharge to avoid polluting the surrounding environment.
③ Waste oil and wastewater from construction machinery shall be treated with effective measures such as oil separation tanks and shall not be discharged beyond standards.
Air environment and dust prevention measures
① Water shall be sprinkled frequently on construction sites and transport roads to minimize dust hazards to production personnel and other personnel and pollution to crops.
② Materials prone to flying dust during transportation shall be tightly covered with tarpaulins, and the loading amount shall be moderate, and over-limit transportation is not allowed.
③ When selecting equipment, choose those with low pollution and install air purification systems to ensure compliance with emission standards.
④ Strict and reliable measures shall be taken for the storage of volatile substances such as gasoline.
Solid waste treatment
① Domestic garbage at construction camps and construction sites shall be stacked in a centralized manner.
② Waste from construction and daily life can also be transported to designated locations after approval by the local environmental protection department. In addition, the construction site must be equipped with flushable toilets, and dedicated personnel shall be assigned to clean and disinfect regularly to prevent mosquito breeding and virus transmission.
③ Scrapped materials or excavated materials from rework during construction shall be immediately transported off-site and buried. Scrap parts, offcuts, cement bags, packaging boxes, etc., generated during construction shall be collected and cleaned up in a timely manner, and site sanitation shall be maintained to protect the natural environment.
Soil and water conservation measures
① Do not cut trees arbitrarily during construction.
② Temporary roads, camps, and temporary production facilities sites shall be hardened and greened to ensure soil and water stability.
③ Implement various drainage measures in a timely manner, collect rainwater into drainage ditches to prevent scouring of slopes and causing soil erosion on slopes.
Environmental protection tax
Since January 1, 2018, the "Regulations on the Implementation of the Environmental Protection Tax Law of the People's Republic of China" has been officially implemented. The project department should formulate more standardized construction plans based on it.