Research On The Appraisal And Reinforcement Method Of The Hole-wall Stability Of Large Aperture Bored Piles In Complex And Rich Water Subsoil

In basic engineering construction, complex rich water soft soil foundation is very common in the coastal areas of our country, the bearing capacity of this kind of foundation is relatively low which often can not meet the requirements of structure form diversification of upper buildings development. Pile foundation is one of the main foundation reinforcement engineering which can increase the overall stability of the foundation and improve the bearing capacity of the foundation. With the development of industrial technology and engineering construction, pile foundation have rapid development in the aspect of technology, design method, bearing capacity, etc. As one of the most basic forms of basic engineering application, pile foundation have great ability at bearing capacity, stability and coordination of uneven settlement which have strong adaptability for complex rich water soft soil foundation. Among them, bored pile is widely used with its advantages of high bearing capacity, soil compaction, construction of no vibration, low noise and suitable for use in city building dense area,etc. But, there are still many problems in the construction process of bored pile, the hole-wall collapse hole problem during the construction of bored piles is particularly prominent. The appearance of the hole-wall collapse problem not only affects the quality and the construction period, but also the potential threat to the safety of the construction and the safety of the related engineering personnel. Therefore, the thorough and systematic research for evaluation of the stability of hole-wall construction of complex water. rich soil in large bored piles and reinforcement method has important theoretical significance and practical application value.Based on the analysis of the testing data of the research and the volume of drilling hole-wall collapse and collapse analysis model for the calculation of hole rate, this paper not only take large borehole cast in place pile hole-wall stability evaluation of foundation soil and reinforcement methods as research content, but also regard the project area of China and Venezuela joint venture Guangdong petrochemical 20 million tons/year crude oil processing project pile project as the study area; according to the basic theory of elastic.plastic mechanics and combining the characteristics of hydro geological conditions in Guangdong petrochemical project, it establishes analysis evaluation model of hole-wall stability elastic.plastic mechanics and determines the Guangdong petrochemical project filling pile construction stable liquid-wall drilling hole-wall stability of elastic plastic mechanics equilibrium condition and instability criterion. Basic principles of fuzzy mathematics theory, it establishes a fuzzy comprehensive evaluation model for bored pile construction of hole-wall collapse risk partition in this area. On the basis of this study, it has the numerical simulation analysis and Research on the construction technology and condition of the stability of the hole-wall stability of Bored Piles by finite element software FLAC3 D. It provides theoretical basis for preventing and controlling the collapse of the hole in the construction process of Guangdong petrochemical project by adjusting and improving the original drilling construction process、proposing the technology route of the whole process control and risk level partition optimization and establishing the preliminary optimization principle and technical control method for the construction of the bored pile in the engineering of bored piles.(1) Sampling inspection on the construction site of the project construction site of Guangdong petrochemical project by developing technical test plan. By using the JJC.1D. type bored pile diameter measuring system for the special inspection equipment of the hole filling pile, collecting parameter of field drilling of the construction of bored piles: aperture, hole depth, vertical degree, thickness, etc, analyzing and studying the data collected from the construction site of the bored pile construction site.(2) Based on the testing data of the research and analysis, putting forward and establishing the hole-wall collapse rate parameter, carrying regression analysis for the correlation between rate of hole collapse and geological parameters by using the least square method, further studying the change law and the collapse mechanism of the stability of the regional construction of the bored piles in Guangdong petrochemical project.(3) According to the basic theory of elastic.plastic mechanics and combining the characteristics of hydro geological conditions in Guangdong petrochemical project, establishing the evaluation model of the stability of the hole-wall and the instability criterion of the borehole-wall and the optimization design method of large diameter drilling-wall stabilized liquid critical proportion.(4) Based on the basic principles of fuzzy mathematics theory, establishing a fuzzy comprehensive evaluation model for the construction of the hole-wall collapse risk of Bored Piles in this area and dividing study area of Guangdong petrochemical project in engineering field of the study area according to collapse risk grade.(5) Carrying out numerical simulation analysis and Research for the construction technology and condition of the stability of the bored pile hole-wall by finite element software FLAC3 D. Conducting a series of numerical simulation research and exploration for deformation law of drilling hole-wall under different groundwater depth, stability ratio, hole diameter, hole diameter, studying and analyzing the stability of bored pile hole-wall under the influence factors.