1) During grouting, if the material feed is normal but the mud level does not move or the return volume is small, it can be judged that a cavity has formed in the artificial hole wall, causing concrete to flow into the karst cave. If this occurs during concrete grouting, immediately contact the batching plant, prepare sufficient concrete, and continue grouting until the returned mud volume is normal, then resume normal grouting.

    2) During grouting, if the mud level suddenly drops, it can be judged that the artificial hole wall has been punctured. At this time, grouting must be suspended immediately, the concrete surface height measured, and the tremie pipe embedment depth calculated. If the embedment depth does not meet the specified requirement of 2-4 m, grouting must be stopped and treated as a broken pile; if the embedment depth meets the specified requirement of 2-4 m, grouting should be resumed immediately until the mud level no longer continues to drop. Then measure the concrete surface height again and calculate the tremie pipe embedment depth. If the embedment depth meets the specified requirement of 2-4 m, grouting should be resumed immediately; if the embedment depth does not meet the specified requirement, grouting must be stopped and treated as a broken pile.

    3) If the mud level suddenly drops as grouting is about to end and the tremie pipe separates from the concrete, this must be treated as a broken pile. Measure the concrete surface height in the hole. If the concrete surface elevation is lower than the karst cave roof elevation, use the steel casing follow-up method to treat the karst cave in subsequent processing; if the concrete surface elevation is higher than the karst cave roof elevation, re-drill after the concrete has reached a certain strength. During drilling, closely monitor changes in the mud level when passing through this karst cave. If there is no mud loss, it indicates that the karst cave has been sealed by concrete, and drilling can continue. If mud loss occurs, the steel casing follow-up method must be used to treat the karst cave to prevent the hole wall from being punctured again during concrete grouting.

    4) When drilling to about 1 meter from the top of the karst cave, change the stroke within a range of 1 to 1.5 meters to gradually puncture the cave roof and prevent drill jamming.

     5) When treating the karst cave roof, if the roof and floor surfaces are uneven, first backfill the hole in layers with rubble and clay, and use an impact drill with a small stroke to impact and cut the hard rock to form the hole.

    6) For empty karst caves or semi-filled karst caves, before puncturing the cave roof, assign a dedicated person to closely monitor changes in the mud level inside the casing. Once the mud level drops, quickly replenish water, then according to the size of the karst cave, backfill clay and rubble at a 1:1 ratio, add whole bags of cement, and then impact and compact. Only after the mud loss phenomenon has completely disappeared should normal drilling be resumed. Repeat this process to allow the drill to smoothly pass through the karst cave.

    7) When encountering an extremely large empty karst cave or semi-filled karst cave, first prepare sufficient block stones, clay, and cement near the hole opening. When the cave roof is punctured, once mud loss is detected, quickly fill and plug to prevent hole collapse. Generally, after the karst cave roof is punctured, the mud in the pile hole will drop rapidly. At this time, use a forklift to promptly throw in the prepared block stones, clay, and cement in appropriate proportions until the mud in the hole stops dropping and slowly rises. Then use the impact hammer to appropriately compact, repeatedly throwing in block stones, clay, and cement until the karst caves on both sides of the pile foundation are filled or blocked. Finally, replenish with mud and re-drill the hole. For large karst caves, wait 1 to 2 days before re-drilling and forming the pile.

    8) For karst caves filled with soft cohesive soil or silt, after entering the karst cave, also throw a mixture of clay and rubble (1:1 ratio) into the hole and impact to consolidate the wall.

   9) When the drill bit passes through a karst cave, closely monitor the condition of the large rope to determine whether the drill is deviating. If deviation occurs, backfill clay and rubble at a 1:1 ratio to more than 0.5 meters above the deviation point, and re-impact.