A concrete mixer truck suddenly encountered a ground collapse while turning. All four wheels sank into the cavity, causing the truck to overturn and crash into two parked cars on the roadside... A residential building, only 20 years old, suddenly collapsed in a catastrophic manner, resulting in one death and six injuries... In recent years, as building safety incidents such as building collapses and road cave-ins caused by underground water seepage have occurred frequently, the long-overlooked issue of building underground leakage has increasingly attracted public attention. According to the National Building Leakage Status Survey Report, jointly released by the China National Building Waterproof Association and Beijing Horizon Market Research & Consulting Co., Ltd., the national underground building leakage rate stands at 57.51%, with the leakage rate in some individual cities reaching as high as 100%. The current situation of underground building leakage in China is far from optimistic.

The root cause lies in the domestic construction market's over-reliance on external underground waterproof membranes. Not only are the service lives and quality of the waterproofing materials used in these membranes questionable, but the underground waterproof membrane system alone is also inadequate due to flaws in the structural design and management of underground structures. As an ancient saying goes, 'If you cut down a tree without digging out its roots, it will grow again; if you harness a river without blocking its source, the water will flow again.' To address underground building waterproofing effectively, we must tackle the problem at its source and emphasize the dominant role of structural self-waterproofing using the concrete structure itself as the primary defense.

The frequent occurrences of ground collapses and building tilting/collapses in recent years are, to a large extent, closely linked to long-term underground water seepage.

In September 2014, near the South Hongmen Bridge in Daxing District, Beijing, a concrete mixer truck encountered a sudden ground collapse while turning. All four wheels sank into the cavity, causing the truck to overturn and crash into two parked cars on the roadside, though fortunately, no casualties were reported. According to workers on-site, the collapse was caused by water seepage from a telecommunications well in a green belt, which washed away the soil beneath the roadbed, creating a cavity approximately 2 meters in diameter under the pavement, ultimately leading to the cave-in. According to another public report, on April 4, 2014, a 20-year-old residential building in Fenghua, Zhejiang Province, suddenly collapsed in a catastrophic manner, killing one person and injuring six, including a young girl who had to undergo amputation. Prior to the disaster, the building had even been awarded as a 'Model Project.' After the incident, technicians conducted quality inspections on seven surrounding buildings. When excavating the foundations, groundwater gushed out at a depth of just half a meter in two locations, and a single water pump operating continuously could not drain it completely. Experts later concluded that the accident was caused by substandard underground waterproofing construction, leading to prolonged underground leakage. This triggered a chain reaction, including steel corrosion, concrete degradation, and alterations to the building's underground structural integrity.

Statistics show that China adds approximately 2 billion square meters of new construction annually, accounting for over 50% of the world's total new construction, making it the world's largest builder of new structures. However, few of these buildings achieve their designed service life.

'There are many factors affecting a building's lifespan, including urban planning, but underground leakage is certainly one of them. With such a massive volume of construction, failing to ensure building safety will plant major hidden dangers,' stated Lai Ming, a member of the Standing Committee of the National Committee of the Chinese People's Political Consultative Conference (CPPCC) and Vice Chairman of the Central Committee of the Jiusan Society.

If the structural self-waterproofing is not done properly, no amount of external waterproof membrane attached to the structure can prevent underground leakage. This is because even the best waterproofing materials cannot guarantee a building's designed lifespan.

Reporters visited multiple construction projects in Shenzhen and the surrounding areas. When asked if waterproofing had been applied, most project managers stated that it had, with some emphasizing that they used the best waterproofing materials available on the market.

In reality, concrete in underground engineering must serve both structural/safety functions and provide dense, waterproofing capabilities. However, the current practice in China neglects these 'structural issues' and instead focuses heavily on 'material waterproofing' for underground projects. The service life of these waterproofing materials is merely 20 to 30 years, a far cry from the expected 100-year lifespan of a building. Furthermore, according to current relevant standards, the warranty period for underground building waterproofing is only 5 years. This stark contradiction between the lifespan of underground waterproofing systems and the expected lifespan of buildings directly impacts structural safety.

Statistics indicate that China currently has a stock of 40 billion square meters of existing buildings, with an annual increase of approximately 2 billion square meters. However, the phenomenon of underground building leakage is growing day by day, highlighting a 'Three Highs' paradox. Despite the increasing sophistication of waterproofing material production and construction technology, and the rising acceptance rate of underground waterproofing projects upon inspection, the actual underground building leakage rate continues to climb. This 'Three Highs' chronic ailment has long plagued the improvement of construction quality in China. Severe underground building leakage significantly shortens a building's lifespan and poses a grave threat to structural safety.