Study On Dynamic Compaction Characteristics And The Effective Reinforcement Scope Of Silt Foundation

Dynamic compaction has been widely applied in engineering field, while present methods of design and construction is still relying on engineering experience, as a result, lack of theoretical basis. Silt and silty clay with high underground water level, easy liquescency, high compressibility and low bearing capacity, are wide distributed in silt foundation of Yellow River Flood plain. Lack of information on the study of the dynamic compaction and the understanding of dynamic characteristics of the dynamic compaction, make it difficult to calculate the effective reinforcement scope and make design and construction of dynamic compaction blindness. The characteristics and of the effective reinforcement scope of dynamic compaction is studied through the theoretical and experimental methods. Firstly depended on the under-construction Ji-dong highway field test, the dynamic compaction stress characteristics along the vertical and radial propagation was analyzed and the simplified calculation model of dynamic compaction effective reinforcement scope was put forward; Secondly model test was designed according to the similarity criterion, and the characteristics of the dynamic compaction vertical dynamic stress were analyzed. And the formula for calculating the dynamic compaction effective reinforcement depth was proposed; With FLAC3D numerical calculation software, the shock wave propagation characteristics and displacement of soil of dynamic compaction were analyzed in this paper, and effective reinforcement area calculation model was put forward; Finally, the calculation formula of dynamic compaction effect reinforcing radius was put forward.Based on the results of field test and theoretical analysis, main conclusions are as follows:(1) Dynamic compaction stress along the vertical distance appears quadratic attenuation trend, and the curve has obvious turning point; Stress along the radial distance appears as the same attenuation trend as vertical approximation;(2) The consolidation scope of calculation model put forward in this paper is a cydariform, and reinforced area can be mainly divided into main reinforcement area, minor reinforcement area and the lower layer;(3) Calculation formula of effective reinforcement depth was put forward and the calculating formula of dynamic compaction effect reinforcing radius was deduced.Benefit by the results, it has important theoretical value to improve the dynamic consolidation technology in this region, and at the same time provides direct theoretical basis for the design and construction of the foundation.