Study On The Control Measures Of Construction Quality Of Mechanical Pore-forming Filling Pile Foundation

Recently, the mechanical pore-forming pile foundation, which has become a common form of pile foundation, mainly has the great advantages of reliably subsoil or embedded into rock formations and the greater single pile bearing capacity. For the coastal areas of marl and karst landforms, the mechanical pore-forming pile foundation has been widely used in buildings and structures, such as bridges, dam and underground space. From two aspects of foundation bearing capacity and the concrete strength of pile, due to the concealment of it and mostly carried out under the water during the foundation construction process, the identification and judge the quality of filling piles are very difficult. Also the foundation cannot be excavated to make the construction quality inspection difficult. In order to ensure the construction quality of pore-forming piles, the construction process should be strictly controlled. For the key and important parts to make preventive measures, the construction quality hidden trouble can be prevented. Therefore, the study on the quality control measures of the mechanical pore-forming filling pile construction is of great significance for the development of building engineering construction.For coastal city of Dalian area, sea overbank geomorphic units are formed after artificial backfill ground. The underground bearing layer locates in the soil for weathered marl and the rock elevation difference is bigger, which is up to 10m subsoil elevation difference between adjacent piles. From the early stage of the survey scheme analysis, cost analysis, construction quality control in the process of analysis, the late pile testing control analysis, the machine pore-forming filling pile construction is conducive to Dalian area topographical features. However, due to its concealment of building construction, it will bring certain difficulty for quality control. According to the experiences of engineering practice, to solve quality control of the mechanical pore-forming filling pile, some of the key technical problems should be researched, so the main content and conclusions in this paper can be briefly summarized as follows:(1) According to a review of the related literatures, the research status and future trends of pile foundation construction are briefly introduced. It indicates that areas for marl or karst areas, mechanical pore-forming filling piles have great prospects of wide use. The method, advantages/disadvantages and the applied scope of mechanical pore-forming filling piles are introduced in detail.(2) The construction process of mechanical pore-forming filling piles are introduced in detail. From three aspects, such as the preparation before construction, pore-forming phase and pile-making phase, the quality control factors of construction process are presented, which shows each procedure of the construction process is of great important. Based on single pile vertical compressive static load test, low strain method, the soil around the pile side friction resistance test, from the groud survey, the construction process and testing, the analysis of quality accidents often occured during construction is carried out and appropriate measures to prevent accidents and countmeasures are presented.(3) Combined with the weathered marl topography zone of Dalian, the reconnaissance and field trials test pile of projects are carried out. Through appropriate testing results, the precautions and countermeasures are summarized in detail and given out. By means of the comprehensive analysis of the marl geological characteristics, mechanical pore-forming filling pile is treated as the most appropriate form of pile foundation.