Jinghe New City Utility Tunnel Project

Background

Located in Jinghe New City, Xixian New Area, Shaanxi Province, this utility tunnel project serves as a key infrastructure component for urban development. It facilitates the concentrated installation of municipal pipelines for power, communication, water supply, and heating beneath the city’s main roads. The tunnel, constructed primarily of cast-in-place reinforced concrete with a total length of about 12.8 km, has a design service life of 100 years. The waterproofing, central to ensuring the tunnel’s durability and safe operation, faced multiple challenges due to complex geological and climatic conditions. Jinghe New City is situated in the loess plateau area north of the Weihe River, with significant seasonal fluctuations in groundwater levels and localized collapsible loess, imposing strict requirements on the waterproofing system.

Solution

The tunnel section employed KIN FLAGO DR HDPE pre-applied waterproofing membrane. The adhesive layer on its underside bonds irreversibly with the fresh concrete upon activation by hydration heat, creating a “skin-like” monolithic bond that prevents water channeling between the membrane and the structure. Its puncture-resistant top layer withstands mechanical damage during construction and later utility installation, accommodating minor deformations from temperature changes and geological settlement. At key details like movement joints, internal/external corners, and penetrations, KINJOYA PU two-component polyurethane coating was used. This reaction-curing coating forms a highly elastic, rubber-like film with over 450% elongation, encapsulating complex geometries and complementing the HDPE membrane. In collapsible loess areas, the substrate was rigorously prepared before membrane installation, including leveling protrusions, repairing honeycomb surfaces, and applying a specialized primer.

Outcomes  

The project employed scientific methods like segmented water testing and shower testing during construction. All tests achieved a 100% pass rate, meeting the highest (Level 1) waterproofing acceptance standards, demonstrating exceptional engineering quality. Since operation began, the interior of the tunnel has remained dry, with no leaks or damp spots. This ensures the safe and stable operation of various municipal pipelines, guaranteeing the smooth functioning of the city’s utility systems. The project’s success has established it as a model for underground space development in Xixian New Area, providing a replicable technical pathway for utility tunnel construction in loess regions.