Reporter: Huangsheng's urban rain and sewage pipe network is not only one of the core issues in the improvement of water environment governance, but also highly related to urban flood prevention and control, urban public health safety, urban road safety and other safety issues. Huang Sheng, associate professor at the School of Civil Engineering, Sun Yat-sen UniversityIn the report, the challenges of flood prevention and control faced by China's urban development, the construction practice of resilient flood control and drainage system, and the deep tunnel drainage system projects of typical Chinese and foreign cities are introduced. In the proposition of sewage pipe network and urban public health safety, he emphasized the need to pay attention to the generation and control of foul odor in the sewage pipe network system, and strengthen maintenance and material selection. In view of the coupling relationship between pipe network diseases and road collapse, as well as the potential road safety hazards generated by the most advanced gas in the pipeline network system, Huang Sheng said that it is necessary to change the gap in construction specifications and standards, the lack of technical guidance, the management of fragmentation, and the lag of pretreatment capacity, and actively promote the construction of the pipeline network and urban safety prevention and control technology system. 1
Pipe network and urban flood prevention and control
Overview of urban flooding in China
On the whole, China is one of the countries with frequent flood disasters in the world, and about two-thirds of the country's land area may have different types and degrees of flood disasters. On the one hand, the impact of climate change has increased the number of extreme weather, and the risk of rain and flood disasters has increased sharply. On the other hand, there is a lack of overall planning for urban flood control and flood control in China, and the relevant infrastructure and maintenance are not in place, resulting in a situation of "lack of capacity" as a whole. The status of China's rain and sewage pipe network
Overall, the total investment in municipal infrastructure fixed assets in cities (including counties) in the 13th Five-Year Plan period averaged 233 trillion yuan, including 194.3 billion yuan per year for drainage facilities and 52 billion yuan per year for comprehensive pipe corridors; The average annual growth rate of the municipal pipe network in cities and towns (including county seats, townships, and organized towns) is 3170,000 km, of which 720,000 km.
The core requirements of the 14th Five-Year Plan for the development of pipeline networks are: to make up for shortcomings and improve safety resilience. In addition to new construction, a large number of old pipe networks need to be repaired and updated, bringing market opportunities for trenchless construction, repair, operation and maintenance of pipe networks. 
Case: Systematic management of urban waterlogging in Zhengzhou
Zhengzhou City formulates a systematic implementation plan for urban waterlogging control, follows the principles of improving the system, highlighting key points, and ensuring implementation, takes problems and goals as the dual orientation, analyzes the causes of waterlogging from the level of regional watersheds, cities and drainage and flood prevention facilities, and scientifically determines the systematic management plan and construction tasks from the three resilient flood control and drainage systems of "integration" of regional flood control in the basin, "one network" of urban drainage and flood prevention, and "one game of chess" for emergency management beyond the standard. Our team is involved in some of these infrastructure construction tasks. Among them, the Jinshui River flood diversion pipeline project involves the super-large diameter JPCP pipe jacking project - 54 km double-row inner diameter 4 m JPCCP (prestressed steel cylinder concrete pipe) pipe jacking project. 
Deep tunnel drainage system
Some urban centers and old urban areas have serious flooding, combined overflow (CSO) pollution, and sewage surges. In recent years, tunnel engineering has attracted attention around the world and has been applied in some developed country cities. Tunnels are mostly built in deep (30 50 m) underground, so they are also called deep tunnels or deep tunnels, which play the role of storage and transportation. 
Among them, the sewage deep tunnel system built in Wuhan's East Lake has been put into use, and it is reported that it can achieve about 4500 million cubic meters of sewage storage capacity. The Hong Kong West Drainage Tunnel in Hong Kong is also the largest flood prevention project in Hong Kong to date.
Pipe network and urban public health safety
Water supply network and water supply security
The domestic water supply pipe network has the following problems: high leakage rate and serious secondary pollution; defects in the initial design, including pipe quality and ground subsidence; poor quality of pipeline construction; There are many problems in the later operation, such as the water supply pressure exceeds the limit. In order to solve these pipeline problems, trenchless technology has been able to meet a variety of needs, including inspection, overall repair, local repair, and manhole repair. 
Corrosion and foul odor in the sewage network
In view of the corrosion and foul odor that are common in the sewage pipe network, we advocate regular cleaning and maintenance, and carry out necessary repair work. Pay attention to the material of the pipe when building a new building, and resistance to microbial corrosion and hydraulic erosion are important considerations in the selection of materials. 
Pipe networks and urban road safety
Pipe network disease and road collapse
At present, China's road collapse is more in summer, increasing year by year, and occurs in a wide area, which has the characteristics of concealment, suddenness, nature, severity and severity. The main cause of ground collapse is the rupture of underground pipelines. The rupture of the pipeline causes leakage, and the water flow erodes the surrounding soil, which in turn leads to the formation of cavities in the groundwater, and finally causes the ground to collapse under the action of engineering construction disturbance or ground load. 
Pipeline network system**Gas generation and road safety
Although this phenomenon is not common, once it occurs, it will cause large losses of people, lives and property. 
On July 9, 2023, an underground pipeline ** incident occurred in Johannesburg, South Africa, due to a leakage of a natural gas pipeline, and the road surface exploded, causing more than 20 cars to roll over or flip on their backs, killing 1 and injuring 48. 
In view of the relevant risks and influencing factors, there is a gap in construction norms and standards in China, and there is a lack of technical guidance. Although the relevant codes and standards have made requirements for sewage treatment and discharge, there is a lack of technical specifications for the explosion protection of underground drainage channels. At the same time, the management mechanism is ineffective and separated. For example, an underground waterway deflagration occurred in an eastern city of China because an oil pipeline was built on top of an existing sewage culvert and then a road. This indicates that the underground situation was not fully understood before the construction of the pipeline. If culmers are avoided, fuel leaks do not enter the sewers, thus avoiding accidents. In addition, there are problems such as lag in preprocessing capacity. 
Pipe network and urban safety prevention and control technology
First of all, it is necessary to strengthen pipeline detection, and quickly and accurately detect the location, direction, and depth of underground water pipelines, metal pipes, cables, etc., as well as the location and size of the damage point of the anti-corrosion layer of steel pipelines, without destroying the ground covering. Secondly, the diagnosis of pipeline pathology was found, and the internal and external repair of the pipeline was carried out.
Clause. 3. Research and development and application of the Internet of Things and big data monitoring and prevention and control technologies, real-time dynamic monitoring of underground pipe network related data, and incorporate them into the overall planning of "smart city".