Evolution Characteristics of Multi-physical Fields in Dissolved Surrounding Rockmass of Tunnel Considering Fluid-solid Coupling

To explore the evolution characteristics of multi-physical fields in dissolved surrounding rockmass during karst tunnel construction, a tunnel engineering calculation model with multiple karst caves were constructed by using the partical flow code (PFC).The parallel bond model was situated among the molecules forming a block cementing material similar to rock.Under the combined action of excavation disturbance and karst water pressure, the evolution characteristics of multi-physical fields in karst cave surrounding rock during karst cave formation were analyzed, including the displacement field, stress field, and seepage field.Results show that the presence of a karst cave stratum increases the displacement around the tunnel and significantly reduces the integrity of the surrounding rockmass.The final displacement value of the tunnel vault is higher than that of its left and right sides.After unloading, the stress field of the surrounding rockmass increases significantly due to dissolution, leading to a significant stress concentration around the karst cave.The cracks initiate and expand rapidly, with the stress concentration occurring at the arch bottom being the most significant.At the same time, a stable seepage field is formed in the surrounding rockmass.The conclusions obtained in this study provide the scientific and practical values for reducing and controlling the occurrence of water inrush disasters during karst tunnel construction.