Since the flood season this year, Beijing, Dalian, Wuhan, Guangzhou, Shenzhen, Chongqing, Hangzhou and other cities have alternately staged the phenomenon of "rainstorm flooding the city", which has been widely affected in recent years.
With the intensification of global warming and the acceleration of urbanization, urban oasis has been reduced, and the heat island effect has been significant, which has made the urban high temperature phenomenon more and more outstanding, which will affect the health of residents and affect people's production and work.
China is now at the peak of urbanization, with its population and wealth converging to the cities, and the urban area is getting larger and larger. The original farmland, ponds and wetlands are gone, and the surface is "hardened"-reinforced concrete is built everywhere, and the streets are full of concrete and concrete pavements. These are not natural water seepage, and the park oasis is not working, resulting in 90% of the rainwater enters the urban drainage system, making it embarrassing and burdensome. Once the city is hit by heavy rain, suddenly the increased rainwater has nowhere to go, and of course it will arbitrarily rush in the city. Therefore, the road instantly becomes a "river", the square becomes a "lake", and it is built in residential areas such as rivers and lakesides. , Factories, etc. have become a lake.
On the other hand, urban land that was originally thirsty, because the surface is mostly covered with impervious concrete and asphalt, it is difficult to absorb the accumulated water on the surface, and rainwater cannot directly enter the ground from the surface, which increases surface runoff and then causes a lot of accumulation. Water constitutes a traffic jam ... Some management departments attribute its primary reason to "lack of talent in urban drainage", as if it was caused by lack of municipal funding. This concept is completely different. In the past ten years, many cities have invested a lot in municipal construction such as hardening and beautifying urban pavements and squares. Buildings, cement concrete pavement bricks and asphalt have been used to cover large areas of the urban area, and high-grade granite slabs can be seen everywhere. The city ground has been completely “hardened”, it is difficult to absorb the accumulated water on the surface, so that rainwater cannot directly enter the ground from the surface, which increases surface runoff, and then causes a lot of accumulated water, which constitutes a traffic jam.
The inevitable result of the "hardened" ground is that this part of the water is discharged to the urban area through the sewage drainage pipe network without being used. In addition, in water-poor cities like Beijing, the groundwater level in urban areas has long constituted a huge “funnel”. It states that despite the lack of water in most cities in China, rainwater is discharged without use. It revealed that China still has a lot of misunderstandings in urban planning, municipal construction and urban management. Many of these "hardened" urban ground methods need to be corrected, and urban rainwater needs to be recovered and used.
2 Learning from foreign experience
At present, some developed countries have very successful experiences and methods in urban rainwater utilization and rainwater collection and utilization. The use of rainwater in the United States is mostly for the purpose of improving natural infiltration. The United States has built an underground tunnel water storage system and established a surface recharge system, which not only uses the ecological environmental function of floods, but also reduces the pressure on flood control.
The German federal and state laws stipulate that it is necessary to consider rainwater utilization systems for new or renovated development zones. Therefore, developers plan and construct or renovate development zones with rainwater utilization as a key content to consider and arrange, especially when establishing large-scale commercial development zones, they also combine development zone water resources practices with tailor-made measures. The use of rainwater is an integral part of upgrading the development zone. After the collected rainwater is treated, it reaches the water quality standard for miscellaneous water, which is used for flushing toilets in street apartments and watering the roads and yards.
Many cities in Japan build "hanging gardens" with rainwater on their roofs, and have large-capacity groundwater ponds to store rainwater. Various rainwater artificial soaking equipment is also built behind many front houses. The collected rainwater is mainly used for flushing, landscaping, fire protection and road spraying after treatment.
One of the most worthwhile experiences we learned during the establishment of foreign cities is: Any construction project, including constructions, municipal equipment, parking lots, roads, etc., must be considered and approved when planning for approval. , Can be beared by the municipal drainage pipe network. If the rainwater runoff exceeds the drainage power of the regional drainage pipe network, the urban rainwater utilization and the development potential of permeable bricks
, it is necessary to choose other compensation methods such as permeable roads to avoid rainwater accumulation and cause damage.
In Western Europe, the United States, Canada, and Japan, the most widely used are permeable pavements that use gap-permeable concrete pavement tiles. The planning principle is: let the rainwater penetrate into the soil as much as possible. When the infiltration rate of rainwater through the road surface is greater than the infiltration rate of the soil, the remaining rainwater enters the municipal drainage pipe network again. In South Africa and the United States, the remaining rainwater that has penetrated through permeable roads is not discharged directly into the municipal drainage pipe network, but is instead discharged into adjacent ponds-blocking the rainwater and gradually entering the surface. In the United Kingdom, tests were made to build "cisterns" in some yards with water permeability. Rainwater was used for daily watering and scouring.
3 Rainwater use and permeable roads
At present, China ’s cities are more severely hardened on the ground, and flood prevention and drainage are required when they encounter heavy rain. However, most cities are very short of water, and it is a pity to blindly drain water. If permeable or semi-permeable bricks are used to lay the semi-soaked ground that can collect rain, then the rainwater can seep to a certain intensity, and the underground volume of the city can be used for storage and can be extracted during non-flood seasons.
According to statistics, the cost of rainwater purification is about 0.2 yuan / t, the average cost of reclaimed water is 2 yuan / t, and the cost of seawater desalination is 6 yuan / t. The recovery and use of rainwater can not only improve the ecological environment, make up for the maintenance of groundwater, reduce floods and droughts, but also save the operating costs of urban drainage equipment. It can be said to be "all things at once". Why not do it?
In fact, the practice of permeable pavement has been widely used in the laying of ancient Chinese cities and traditional courtyards. Unfortunately, in today's eager pursuit of building a “modern” city, we have not realized the value and meaning of water permeability on the ground of the city, laying a lot of
On the impermeable and hardened ground, the results have caused a series of urban disasters and negative effects, and the loss is heavy.
There are three ways to collect and use rainwater in urban construction and construction projects: if the roof of the building is hardened, rainwater should be collected and introduced into oasis, permeable roads, or water storage equipment; if it is a hardened ground, sidewalk, etc., it should be selected Permeability data paving, or creating confluence equipment to introduce rainwater into pervious areas or water storage equipment; if the ground floor equipment such as urban trunk roads is on the ground, rainwater utilization equipment should be created along with beautification irrigation along the line.
Permeable pavement refers to the use of pervious building materials such as permeable concrete, permeable asphalt, permeable bricks
, and turf bricks to replace conventional concrete, asphalt, and glazed bricks
, etc. The permeable pavement can quickly soak rainwater under the roadbed, and even reach the underground aquifer. Water on the road surface will not occur.
As an ecological city, the area laid on the permeable ground should include sidewalks, pedestrian streets, bicycle lanes, suburban roads and outing walking roads; open-air parking; the grounds around the houses, yards and streets; driveways, public squares, and so on.
Experienced rainwater application skills, from rainwater collection, pollution interception, storage, filtration, infiltration, reuse to control, have a series of shaped products and complete sets of equipment, permeable bricks are
only one of them.
The so-called permeable bricks are floor tiles
that can drain rainwater naturally and quickly when heavy rain comes. There is also a lesser effect called the seepage brick, which is a floor tile with a certain function of seepage. These two types of bricks are new building material products produced by mixing water-permeable additives and water-conducting materials in granite bone guessing.
Because the permeable brick
has outstanding water permeability and moisturizing function, it can well alleviate the "urban desertification" and "heat island effect" brought by the city's covering on impervious ground, which is conducive to maintaining the city's water balance and avoiding heavy rain disaster. Permeable bricks come
in a variety of standard shapes, with prices ranging from 40 to 170 yuan per square meter.
(1) High water permeability. Because the permeable brick
has a high porosity, the special connecting holes can allow rainwater to enter the ground, so that the groundwater can be compensated, and the disadvantages of imperviousness of urban roads (including concrete, asphalt roads and cement bricks, porcelain square bricks, etc.) are overcome. , And then slowed the downward trend of the ground caused by the decline of urban groundwater levels. In addition, because part of the water enters the ground, this reduces the pressure on urban waterways and the pollution of rivers and lakes, and also reduces the cost of sewage treatment.
(2) Because the primary raw material for making permeable bricks
is industrial waste residue, the production of permeable bricks
reduces the environmental pollution caused by industrial waste residue. Together, its production cost and price are lower.
(3) Because of the high water permeability and outstanding decoration effect of permeable bricks
, it can replace other similar construction materials.
(4) Because the porosity of the permeable brick
is high, it has good sound absorption and has the function of reducing noise pollution.
(5) The surface friction coefficient of the permeable brick is
large, and it is convenient for pedestrians to walk on it.
According to the production process, permeable bricks
can be divided into two types: sintered permeable bricks
and non-fired permeable bricks
. The sintered permeable brick
is made of inorganic non-metal materials (including solid industrial waste residue, daily waste and construction waste) as the main raw material. It is a floor tile
with large water permeability after being crushed, sieved, and shaped. . For example, permeable bricks
using fly ash as the primary raw material have a mass ratio of 40% to 50% fly ash, 25% to 35% clay, 20% to 30% waste brick aggregate, and a particle size of 0.45 to 0.6mm. , Molding pressure 25MPa, firing temperature 1050 ° C. Product quality inspection shall meet the requirements of JC / T 945-2005 " permeable brick
Non-fired permeable bricks
are made of inorganic non-metal materials as the main raw materials. They are made of organic or inorganic binders and formed and cured. Because it is not fired at high temperature after molding, it is called non-fired permeable brick
The collection and recovery of rainwater is a systematic project. Pervious pavement is a method in the meantime. It requires a series of technical standards and standards to support it before it can complete the recovery and use of rainwater. For example, a joke where a cement was placed under a permeable brick was
made somewhere makes the permeable brick
When building permeable pavements, we still have some shortcomings. For example, without the relevant technical standards, how strong is the strength to satisfy the requirements of the underlying structure? What is the difference between paved sidewalks and driveways? What is the cushion structure when paving? Until some problems are not dealt with, the anti-slip problem can only be dealt with first. Therefore, nowadays, cheaply permeable bricks are used, and concrete cushions with a thickness of about 5 cm are played under the bricks.
As a new type of building material, permeable bricks
must have a continuous improvement process in the promotion and use. In order to avoid detours, we can learn the practice of permeable floor and permeable bricks
in Germany. They start from public areas, such as sidewalks, pedestrian streets, bicycle lanes, suburban roads, outing pedestrian roads, and public squares. The city ground was converted into a permeable ground.
Rainwater recovery skills are an important part of water-saving and energy-saving skills. At present, China's urbanization has entered a stage of rapid development, which will surely bring more land into construction land. In this process, rainwater must be recovered and used as part of urban planning for planning and creation, so as to compete for the huge wealth of rainwater to bring benefits. Brick and tile enterprises should seize this valuable opportunity to continuously develop and improve permeable bricks
, and make more contributions to avoid urban floods and create ecological cities.