Abstract
There is high risk of water inrush and ground collapse accidents when tunnelling in karst areas. Based on the case study of an urban metro tunnel, this paper focuses on karst cave treatment and waterproofing strategies for earth pressure balancing (EPB) shield tunnelling in karst areas containing large amounts of karst caves and fissures. When the shield machine enters the karst area, water gush easily occurs, posing serious threats to tunnelling safety. The distribution characteristic of limestone fractures, karst caves, and fissures in the karst area were analyzed according to the geological survey results. Further, water inrush risk and engineering difficulties were analyzed. Subsequently, a compound karst cave treatment and waterproofing strategy for EPB shield tunnelling was proposed and implemented. Water inflow is successfully reduced and ground collapse accident is avoided using the compound karst cave treatment and waterproofing strategy.
Highlights
Karst is formed through complex chemical and mechanical interactions between groundwater and soluble rock formations such as limestone, dolomite, gypsum, and halite, which can develop into karst caves, karst conduits, and corrosion fissures with a variety of sizes and shapes
This paper focuses on karst cave treatment and waterproof measures for shield tunnelling in limestone formations based on the case study of R3 Metro Line in Jinan
The compound treatment measures have effectively reduced the risk of geohazards and provided an reliable environment for the subsequent shield tunnelling
Summary
Karst is formed through complex chemical and mechanical interactions between groundwater and soluble rock formations such as limestone, dolomite, gypsum, and halite, which can develop into karst caves, karst conduits, and corrosion fissures with a variety of sizes and shapes. Special karst cave treatment and waterproofing strategies should be adopted to avoid water inrush and ground collapse accidents when tunneling in karst areas (Li et al, 2013). This paper focuses on karst cave treatment and waterproof measures for shield tunnelling in limestone formations based on the case study of R3 Metro Line in Jinan. A compound karst cave treatment and waerproofing measures for shield tunnelling in limestone formation is proposed and implemented in the limestone section. There is high risk of geological disasters, such as cave roof collapse or water and mud FIGURE 3 | A real image of detected karst cave in limestone formation near the tunnel. According to the above analysis of geological features and engineering difficulties of the limestone section, a compound karst cave treatment and waterproofing strategy is proposed. The compound treatment measures have effectively reduced the risk of geohazards and provided an reliable environment for the subsequent shield tunnelling
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