Research On Settlement Calculation Of Pile Foundation In Deep Soft Soil

With the development of China's economic, civil construction developed rapidly, especially the transportation construction, in which the construction of high-speed railway is greatly boosting the economic development. Bearing capacity of railway infrastructure problems was people's main concern in the past, but with the high-speed railway operation, smooth ride and safety has become a new topic. Due to the high bearing capacity, good stability, small and uniform settlement, adaptability, etc of the group pile foundation, it has good economic and broad application prospects. For decades, domestic and foreign scholars have made considerable achievements on the settlement of pile groups; however, the research of deep and soft soil in the settlement is still not perfect.Based on the major scientific project of Beijing-Shanghai High-speed Railway "Research on Post-grouting Technology for Pile Foundation in Soft Soil in High-speed Railway", this thesis started from the description of the group pile foundation theory and analyzed the influencing factors of the settlement of pile foundation in deep soft soil, and recommends settlement calculation method based on Mindlin solution for settlement calculation of pile foundation in deep soft soil. Reasons are as follows:1, relatively weak in the deep soft soil, subsoil cap minimum load sharing, based on Mindlin method of settlement calculation method, the accuracy can be better met.2, under the load the calculation method of pile foundation's additional stress, Mindlin solution is closer to reality than the Boussinesq solution, and more accurate.3, because of the group pile foundation has these features, such as more pile number, larger pile spacing and the longer pile, settlement calculation based on Mindlin solution can fully take the number of piles, pile spacing, pile and pile length on the settlement influence into account. In which the soft soil as deep pile foundation pile length is longer, settlement calculation method based on Mindlin can fully considered its own pile of concrete compressive deformation, calculated using elastic compression of pile, it can be More in line with realistic settlement mechanism.4, method based on Mindlin solution for settlement is more concise than the FLAC 3D numerical model.Compared and analyzed the FLAC 3D numerical model results with field test data we can see that column load size and distribution of the calculated agreed with the experimental data better, Numerical simulation of pile-soil stress results is too larger, but the distribution is consistent with the test,so we can determine the accuracy of numerical model results to provide meaningful suggestions for deep pile foundation in soft soil settlement calculate.