| Punching pile is a common form of pile foundations,which using punching machine exerting repeated impact on the hard soil or rocks with the dead-weight of pounding bit.Thus, the pile hole has been formed, the slags-mud has been squeezed into the hole wall,.and the remained slags has been removed by mud circulation as well.At last, reinforcement concrete has been poured.AS a kind of extensive used pile foundation,punching pile can be applied to all types of geological environment,which has some incomparable advantages over the others pile foundation forms such as rugged pounding hole,simple equipment,convenient operation,stable wall of the hole within mud circulation slag-removal and low energy consumption.On the basis of summarizing the shortage of the existing construction technology of punching piles,this paper has studied the whole set of construction technology which concludes hole pounding,reinforcement cage-hoisting,underwater concrete pouring,pile integrity-detecting and mud hand-ling.Construction technology as well as quality problems of each single process have been analyzed.Some basic principles of the key technology has been elaborated. Combining with project practice, some key technology has been optimized, some quality control measures have been put forward.The main works is as follows:(1)Punching reverse circulation method can break rock into the hole quickly and remove the slags efficiently.The paper has carried on the analysis to the pounding parameters from the movement of energy.On the basis,punching reverse technology has been elaborated,mud circulation and slag removal control have been studied,common quality problems during hole-forming have been summarized,also,preventive measures are put forward.(2)The paper has carried on the study of the production,hoisting,centering and floating control of reinforcement cage,which focusing on centering technology and stress state.The influence factors lead to floating and anti-floating has been analyzed. The measures that control the floating has been put forward as well.(3) Studied the fluid mechanics and dynamics principle over the underwater concrete pouring.Concrete technology concluding the production, tremie installation,first batch of concrete pouring as well as pouring speed control etc. Has been analyzed.Incidental quality problems has been summarized and the prevention-control measures are put forward.(4) Sonic transmission method is widely used in pile integrity detecting,which is characterized by accurate detection result convenient operation and not affected by the characteristics of pile length or slenderness.This paper introduces the fundamental principal of sonic inspection, optimizes the number of embedded acoustic pipe and its installation process and applies the method to pile integrity of a specific project.(5)slurry can not only maintain the stability of the hole wall, but also clean slags through the mud circulation.This paper has described the performance requirements, preparation and utilization of high quality mud,designed the mud circulation system,studied the dehydration and solidification of sludge. with the specific project as an example,the environmental benefits and economic benefits of mud recycling are briefly analyzed.Through the research, after the technology improvement and optimization of punching piles, the construction quality has been improved,the construction cost has been reduced,the civilization and environmental protection in construction site has been guaranteed.The results of the paper can give some reference to the construction of punching piles. |
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