【正文】 , mostly around the elimination of pile bottom sediment, a pile of weak interlayer. (1)pre loading method in advance of the pile bottom for preloading, the pile soil paction, improve the bearing capacity of piles. But timeconsuming, costly, and not easy to implement. (2) extending end bearing area. The belled pile, in the past used in engineering is more, but on the bottom of pile soil are still incapable of action. (3) sand lining pile technology : the method for castinplace pile, construction, use double sleeve around the pile in sand filling, bee sand set of about 3 ~ 10cm, sand set can improve the lateral wall of the friction resistance of pile. (4)Grouting technology:routing technology grouting method can be divided into the first grouting and grouting method. The first method of grouting is drilled in the Kong Zhuangcheng hole and before concrete grouting, the nozzle pipe into the hole bottom is inserted into the soil, spraying slurry, so that at the bottom of pile soil mixed with cement, then pile concrete. Pile cap Cap refers to bear, distribution from pier to carry the load on pile top, set to connect all the top of the pile of reinforced concrete platform. Cap is piles and columns or piers contact part. The root cap, even ten piles are linked with the formation of the pile foundation. Cap for high pile cap and pile caps: low pile cap generally buried or partially buried in the earth, high pile cap generally above the ground or water. High rise pile cap having a free length, the surrounding supporting body to withstand horizontal load. Pile stress situation is extremely unfavorable. Pile internal force and displacement under the action of external force than the same level of low pile cap to be big, the stability is poor because of low pile cap. High rise pile cap is generally used for port, wharf, marine engineering and bridge engineering. Low pile cap is generally used in industrial and civil buildings. Pile head generally into platform meters, and a reinforced anchor into the cap. Platform to build on the columns or piers, forming a plete power transmission system. In recent years due to the large diameter bored pile, pile rigidity, strength is big, so high pile in bridge foundation construction has been widely used. 灌注樁 概述 鉆（沖、挖）孔灌注樁，從 20世紀 60年代初在河南省南陽地區(qū)研制應用以來，因其具有眾多的優(yōu)點，已廣泛應用于包括軟土、黃土、膨脹土等特殊土在內的各類地基和工業(yè)、民用、市政、鐵路、公路、港口等各類工程實踐中。 when the hole wall is not easy to collapse, not more than 20cm. For the post, in water or shoot the breeze, sediment thickness less than 5cm. Hole cleaning method is to use different and flexible application of drilling rig. Usually you can use normal circulation rotary drilling rig, reverse circulation rotary machine vacuum suction machine and slag pumping cylinder hole cleaning. The mud suction machine hole cleaning, required equipment, convenient operation, hole cleaning is thorough, but unstable in the soil should be used cautiously. Its principle is to use pressor generates high pressure air into a suction dredge pipeline will mud blowing. (7) pouring underwater concrete After finishing hole, can be prefabricated reinforcement cage hanging vertically into the hole, positioning to be fixed, and then using a perfusion catheter concrete, pouring concrete don39。s