Numerical Simulation of Small Unconnected Karst Caves Grouting and Crack Quantity Impact Based on Fluent Software

Abstract

Objective Grouting treatment of karst caves is a challenge in metro tunnel engineering, as improper handling of karst caves during construction can easily lead to accidents. Therefore, it is necessary to study the relationship between the quantity of cracks and grouting pressure in small karst caves. Method To address the uncertainty regarding the quantity of cracks in urban small unconnected karst caves (with a volume not exceeding 8 m3) that requires grouting filling, numerical simulations of cave grouting with different crack quantities are conducted using multiphase flow Mixture model in Fluent numerical simulation software. The variation of grouting pressure in the test area during simulated grouting is calculated over time and compared with karst caves grouting pressure data from practical engineering. Result & Conclusion For small unconnected karst caves with a volume not exceeding 8 m3, the grouting pressure in the simulated test area shows an inverse square relationship with the quantity of cracks, and decreasing as the crack quantity increases. When the crack area reaches 0.048 m2, the grouting pressure no longer decreases. The grouting pressure decreases with the increase in the elevation of crack locations. In practical engineering, comparing grouting pressure data among the same type of small unconnected karst caves with volumes not exceeding 8 m3 can serve as a basis for judging the relative quantity of cracks in karst caves, thereby adjusting and optimizing subsequent grouting schemes.

Keywords

• metro
• small unconnected karst cave
• crack quantity
• grouting pressure