| With the development of the city, various building or construct infrastructures, such as highway and railroad etc. need construct on the miscellaneous fill. People's consciousness of environmental protection gradually raised in the meantime, the relation between ground treatment and environmental protection should be well handled. Therefore the research on the ground treatment technique of miscellaneous fill, especially for the deep miscellaneous fill, is very necessary.The engineering properties of miscellaneous fill include: unit weight, water content, porosity, coefficient of permeability, shear strength and compressibility. The influencing factors of the miscellaneous fill's properties include: fill time, filling and theirs combination property, compactness, ground water erode and subjacent bed lithology.When choosing the ground treatment method of miscellaneous fill, people should consider that the miscellaneous fill ground has differential property, various thickness, low strength, high compressibility and strong collapsibility and self-weight consolidation, and the problems of filtration liquid polluting soil and groundwater, the H2S etc. poisonous gas, venom, poison and enrichment methane imperiling people, producing negative friction etc. . Analysis and selection result shows that the pile filler is well fit for treating deep miscellaneous fill. The pile filler can acquire material locally, have low price, and have the characteristics of green engineering; have high kinetic energy and strong compaction effect, good uniformity, evidently raise ground's bearing capacity. The pile filler body presents the form of a string of bead in the layering soil. Pile and soil present the phenomena of "occlusion" and "enclasp". The construction goes in brief and easily.The macroscopical working mechanism of the heavy-hammer rammed-expanded compaction pile uses the high pressure and the function of dynamical thrusting, smashing and squeezing to compact the soil, which not only makes the pile body compact, but also makes the soil round the pile be subjected strong side compact strength. Strength releasing produces great side restrained "enclasp" effect after the pile forming. Therefore the pile body has the characteristics of the rigid pile and flexible pile. For the layering ground or non-uniform soil, the pile body will become a string of bead in the construction, favoring for the pile and the soil round the pile to closely "occlude" to increase side frictional resistance. The pile and the soil among the pile form compacted whole after reinforcement. The microcosmic working mechanism of the heavy-hammer rammed-expanded compaction pile is that the soil structure produces "aggregation" under wallop. The smaller soil grain parallel alignment following the big grain under wallop, the circinate structure appears in soil. This kind of structure makes the engineering mechanics property of the soil improved. The compaction of soil includes:(1)the huge impact makes the "overhead " structure of soil break and the hole volume reduce;(2)under the huge impact, the soil grain is sheared, broken up or the sharp angle broken up then filled and crowded, which makes the soil more compacted and the structure more stable(;3)The volume compression is caused by the flexibility of miscellaneous fill grain. The compound ground is not only rigidity even, but also its bearing behavior is evidently improved.Using ANSYS model to analyze the effect of pile filler treatment for miscellaneous fill, ANSYS model can well reflect the soil's displacement during thrusting. The simulation result is consistent with measure result and experienced value.The laboratory and in-situ test did about pile filler, grouting and ram-compacted piles with bearing base in miscellaneous fill, the result shows that the field's bearing capacity and settlement is satisfactory for design after treatment. Using cladding and discharge treatment technique in different district on the whole field can effectively control the field's gas creation.
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