The Analysis Of Pile Groups Settlement Under Additional Loads Caused By Garden Soil Fills

With the development of the living environment request, the top of large underground garages are covered with garden soils in a great many residential quarters to increase small area green turn. This situation will cause rather large additional stress in the ground while the additional stress will result in block settlement and non-uniform settlement of foundations between the main building and underground garage. For the ground that soft underlayer exists, if do not consider the situation described above during the design, the soft underlayer may induce more compressible deformation. Therefore, punching failure might take place. However, the research concerning this situation is rare.Firstly, it is analyzed the settlement behavior of single pile under the surrounding additional loads, based on the theories of pile groups settlement and summarizing of settlement calculation methods, then represents the single pile load-transfer methods taking the negative skin friction into consideration and compares the distribution and development behavior between positive skin friction and negative skin friction, discovering the regulation that all of both are from top to bottom to stir up gradually, and the ultimate friction is worth to enlarge with the depth etc.Secondly, it goes forward to go correction on the foundation of the flexible theories method by Poulos, considering the foundation as rigid plank, this paper carries out the single analysis with load-transfer methods represented in chapter 2, takes mutual affection between pile and soil in pile groups into consideration with Mindlin solution, then deduces the hybrid method and uses this method to analyze the pile groups settlement behavior in common situations. Meanwhile deduces the approximate formulation to calculate the critical affection thickness of load bearing layers under pile tips and soft underlayers and minimum thickness formulation of load bearing layers from the additional stress determination at the top of the underlayer.At last, this paper considers the pile groups settlement and load distribution behavior affected by the additional loads which is caused by garden soil fill around the foundation, takes the "shield effect" of piles and soils outside the pile groups into consideration, assumes surrounding additional loads only affecting piles and soils outside the pile groups, then modifies the hybrid methods deduced above and establish MATLAB programs. Comparing the pile groups settlement behavior and load distribution along the pile and in the soil between the general situation and the situation under the surrounding uniform additional loads, it is derived the variable rules of pile groups settlement and load distribution behaviors under non-uniform additional loads. Finally it is certificated the rationality of the method derived in this paper, by analysising of the engineering example, and put forward some usefuless engineering improve measures.