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Abstract: In underwater concrete pouring, in the event of an accident, appropriate measures should be taken to prevent the accident from worsening or to minimize losses as much as possible. This article analyzes some possible accidents and proposes corresponding solutions. Keywords: underwater concrete; accident handling. At present, the construction of bridge pile foundations mostly involves pouring underwater concrete. Although years of experience and insights have been accumulated in this process, unforeseen accidents still occur frequently during construction, ranging from broken piles to floating cages, which affect the construction process and result in economic losses. I. Pipe jamming during ball cutting: When pouring underwater concrete, pipe jamming occurs during ball cutting, and there are two reasons for this phenomenon. 1. Improper preparation of the ball: The diameter of the filler ball differs too much from that of the conduit; before cutting the ball, mortar or fine aggregate seeps into the space between the conduit and the ball’s wall, causing blockages. In such a case, without wasting any concrete, there are two emergency solutions: (1) Use steel bars of a certain length (usually about 2m longer than that of the funnel) and a diameter of 20mm to 25mm to push the balls aside, allowing the concrete to flow down. ⑵ Using mechanical vibration to cause the concrete to fall requires skilled operation techniques to ensure that the conduit returns to its normal position once the concrete has fallen. 2. Unqualified concrete: If the slump of the concrete after it is prepared is too low or if it is not mixed evenly, and if the coarse aggregates sink during the accumulation of concrete, this can cause the coarse aggregates at the funnel opening to press together tightly, thereby blocking that opening and making it difficult for the concrete to flow down after cutting. The remedial measures are the same as above; it should also be noted that, generally, the slump of the first batch of concrete should be kept within the upper limit specified by the standards for concrete slump in underwater conditions. To ensure smooth ball formation, the amount of aggregates used can be adjusted appropriately, and after the ball formation process is complete, mixing can be carried out using the normal mix ratio. If the concrete still does not settle after taking measures and a long time has passed, there is no choice but to discard that batch of concrete; the hole must be cleaned appropriately or disturbed at the bottom using an air compressor before pouring concrete again. II. Pipe blockage during pouring: Mechanical failures (such as power outages) cause the concrete to remain in the ducts for too long, or the pouring process takes too long; as a result, part of the concrete begins to set, increasing the resistance to its flow and leading to blockages in the ducts. Such accidents should be prevented primarily. The equipment should be thoroughly inspected before perfusion. Make the pouring as continuous and rapid as possible; during hot seasons, add an appropriate amount of retarder to the concrete at the beginning of pouring to prevent premature setting of the concrete. If pipe jamming occurs at a concrete pouring depth of within 3m and it cannot be resolved to allow continued pouring, it is recommended to stop pouring, remove the conduit, use a sludge extractor to remove the concrete, clean the hole again before resuming pouring. Alternatively, lift the rebar cage, lower the drill bit again, increase the slurry concentration to reach the designed depth, remove the already poured concrete, then clean the hole in the usual manner and pour again, thus achieving high-quality work at a minor cost. If the thickness of the poured concrete is large, it is unlikely to be possible to drill out the hole again; instead, it is necessary to replace the conduit and pour concrete once more. However, how to ensure that the pile remains intact after replacing the conduit is something that needs to be studied. III. During the pipe pouring process, there are two possible reasons why the conduit cannot be pulled out: 1. The quality of the rebar cage is poor, and some rebars separate from the main rebars and get inserted into the hooks on the conduit (in this case, the cage tends to float). At this point, the conduit should be rotated back and forth to separate it from the rebar cage and align it at the center of the borehole, after which pouring can continue. 2. An excessive burial depth of the conduit, or the initial setting of the concrete, increases the frictional forces between the inside and outside of the conduit. When pouring concrete underwater, the burial depth of the conduit must be strictly controlled to be no more than 6 meters and not less than 1 meter. To prevent the initial setting of concrete, in addition to adding an appropriate retarding agent, the conduit should also be vibrated. Once tube entrapment occurs, it is necessary to first determine the exact cause, and then apply as much pulling force as possible to remove the catheter (while preventing it from breaking). During the removal process, the catheter should be shaken back and forth to make it easier to extract. IV. Floating cages: Accidents involving floating cages are not uncommon during the pouring of underwater concrete, and they are particularly likely to occur in bored piles that have only a lower cage section (i.e., when the length of the rebar cage is less than the depth of the hole). The cause of this phenomenon is related to the thrust exerted by the concrete, but inadequate prevention is also a factor; therefore, relative fixing measures should be taken when lowering it, by welding as many main rebar bars as possible to the drill rig base in order to increase the fixing strength. It is necessary to know when, during the pouring process, the concrete will approach or enter the rebar cage. As the concrete surface approaches and enters the rebar cage, it is necessary to maintain pipes at a sufficient depth within the permitted range, and to pour concrete continuously in order to minimize the impact force exerted on the rebar cage by the concrete emerging from the bottom of the conduits ； Once the concrete surface reaches a certain depth below the rebar cage, lift the conduit appropriately to increase the depth of burial of the rebar cage, thereby ensuring sufficient bond between the concrete and the rebar cage so that the cage does not rise upward. If floating occurs, it should be dealt with as soon as possible to prevent further upward movement. It is best to wrap the main rebar of the reinforcement cage with several steel pipes having a diameter of around 6 cm, then weld them to the casing. Rebar or square timber can be used to form a network that presses down on the welded steel pipes and the casing; this also helps to ensure that the reinforcement cage does not shift too much as it floats upward. Construction accidents occur from time to time; to ensure project quality, it is necessary to adhere to the principle of prevention first and addressing issues at an early stage.