The mud water of perforated pile driver is a more serious quality problem which is easy to be revealed by the pile foundation construction, and the main reasons are as follows: 1. The clearing of perforated pile driver is not thorough. The slag particle size is too large, the mud water of clearing the hole has no way to make it flash suspended condition and bring out the pile hole and become permanent slag. 2, the mud water after clearing the hole of punching pile machine has too large specific gravity, resulting in the injection of cement, the impact of cement can't be absolute to the bottom of the hole of the pile of the mud water back up, resulting in mixing of the slurry. 3, after the clearing of the hole of the punching pile machine to the cement after the opening of the irrigation time is too long, so that the slag which has already been in the suspended condition sinks back to the bottom of the pile hole. The slag is too thick to be counteracted and become permanent slag, which leads to the problem of construction quality. 4. The lower end of the conduit injected by perforated pile driver is too high from the bottom of the pile hole, which affects the counteracting effect of the impact of cement on the mud water at the bottom of the pile hole, and may lead to the cement injected at the beginning has no way to wrap around the lower end of the conduit, which leads to mixing of slurry and entrapment (pile breakage). 5. Initially injected cement collapse is too small, poor fluidity, which affects the impact effect of cement and leads to bottom slurry. 6. The inner wall of the conduit is too not fine, roughness is not enough, which reduces the falling speed of cement in the conduit when injected at the beginning, which affects the impact effect of cement and leads to bottom slurry. Avoid and dispose of the pile bottom slag is too thick or mixed slurry treatment methods are: (1) really check the rock slag material diameter of the clearing stage, and the specific gravity of the mud water after clearing. In order to increase the effect of mud water clearing, can participate in the mud water additives (such as sodium sulfate, etc.) to increase the colloidal stability of mud water. (2) Strictly choke the stopping time after clearing the hole. If the time is too long, should be injected into the cement conduit from the new hole, and then implement the underwater cement injection. (3) Strictly control the distance from the lower end of the conduit to the bottom of the pile hole, which is generally about 30㎝ and should not exceed 50㎝. Ensure that the amount of cement injected at the beginning can cover the lower end of the conduit, so that the initial buried depth of the conduit is not less than 1 m. (4) Strictly control the degree of collapse of the cement to ensure its mobility; often thoroughly organize the inner wall of the conduit to ensure its "roughness", so as to prevent the piston from dropping down in the conduit poorly when the cement is injected at the beginning, which results in congestion of the conduit and affects the quality of cement injected into the core of the pile. Cement injection quality. (5) For pile holes larger than 35m, when it is considered appropriate to use positive cycle dynamic work to clear the holes without certainty, pumping machine should be used to consider appropriate to use reverse cycle dynamic work to clear the bottom slag of pile holes, so as to ensure that the thickness of the bottom slag of the pile after pile formation does not exceed the permitted thickness of the dynamic work specification. (6) For the pile bottom slag is too thick and affects the quality, the commonly used disposal method is to utilize the core hole of the core inspection and determination or the ultrasonic probe observation to observe the probe observation tube as a channel, and consider it appropriate to use the high-pressure grouting to implement the reinforcement of the pile bottom. Practice has confirmed that the effect of this disposal method is more ideal.