Study On Jacked-in Pipe Pile Resistance In Songhua River Floodplain Areas

Jacked-in pipe pile is widely used in practical projects with the merits of vibrationlessness, noiselessness, low cost, small construction place and the capability of supervising the entire process. At present, in Guangdong, Shanghai and other cities, Jacked-in pipe pile foundation has been studied theoretically according to local geological conditions, and their construction experience and technical regulations are in the forefront of the country. In Songhua River floodplain areas, design department can only learn experience and relevant technical regulations from Guangdong Province when designing Prestressed Concrete Pipe Pile. Basic theoretic research on Jacked-in pipe pile is obviously lagged behind engineering practice because there is no technical regulations of design and construction suitable for this region.Before pressing the pile, if piling resistance and ultimate pressure are simulated and computed, then the design of pile style, prediction of pile length, selection of construction machine,and possibility of pile penetration can be worked out. Based on the information and locale report on the Jacked-in pipe pile about three representative actual project in the floodplain of Songhua River, piling resistance was estimated in this region and pile driving features was analyzed. This article reads as follows:First of all, theoretical and numerical analysis methods of current pile pressure were introduced, and each of these theoretical deficiencies was pointed out; pile driving mechanism, effects of soil compaction and other issues about Jacked-in pipe pile were presented, on this basis, many methods for estimating driving resistance of Jacked-in pipe pile cited by experts were enumerated, and the ultimate pressure and pile driving control standards were analyzed.Secondly, CPT process and piling pressure Pipe were compared to confirm the feasibility of estimating pile driving resistance by using CPT information. According to three projects CPT information and the measured pressure piles report in Songhua River floodplain areas, piling resistance calculation procedures was established by Matlab.Comprehensive correction coefficient and calculation range of resistance of pile tip looked as variable parameters, the piling resistances in different soil layers were gained, and comprehensive correction coefficients in different soil layers were also got by comparative analysis with actual pile pressures.Finally, in accordance with engineering geological conditions in pile driving areas, ANSYS software was adopted to analyze numerical value of jacked-in pipe pile by displacement penetration method,and stress field and displacement field of pile pipe in every depth of soil layer were acquired. Elasto-plasticity DP constitutive law was chozen, and the influence of large deformation at interface and sliding between pile and soil were taken into account,which made the result more resemble to actual process of pressing piles. Piling resistance and friction around pile were got.