The Test Of Applying The Dynamic Compaction Treatment Method For Liquefied Ground In Highway Engineering

The methods for Liquefied ground treatment have been studied for years around the world. Specifically, the dynamic compaction treatment method has been investigated and applied in industrial and civil construction projects. However, this method is seldom applied in highway projects. Some effective methods in Industrial and Civil Engineering may not fully applicable in Highway Engineering. The main attributes of Highway Engineering include:a highway project is a large linear project and the construction width is narrow; a highway project need to handle long road sections; any adjustment of the design parameters in a highway project may have great socio-economic influence; the design parameters may be complex because the highway may be across different geomorphological units; the requirements for the ground may be various along the route because of the structures all around. In addition, the quality test methods in treatment of liquefied foundation, such as loading test method and standard penetration test which are conventional methods applied in industrial and civil construction engineering, are limited in highway engineering. To solve these problems, the thesis identifies the main design parameters of the strong punned method in the treatment of liquefied foundation of expressway by test. The parameters include rammer, falling distance of rammer, optimum tamping energy, rammer points layout and distance, cushion settings, reinforced area and so on. Field test results show that, the lager the capacity for single tamping, the larger the tamping settlement. With the number of tamping increasing, the average volume of a single tamping settlement decreases linearly; the pore water pressure accumulates, reaches maximum in the first hit and tends to stabilize after the best tamping times. Generally, pore water pressure in the shallow part is lager than the deep part. Whatever the main tamp, vice tamp,or full tamp is adopted, pore pressure can dissipate more than 90% after tamping 24 hours. In the case of individual lots for the clay surface layer, it can be dissipated by 90% within 72 hours.Thus,72 hours is determined as tamping intervals.The thesis analyzes the factors influencing the effective reinforced depth of the strong punned method in treatment of liquefied foundation of Expressway. In addition, Comparing the testing results of SPT and CPT, the author suggests the SASW method, which is a fast and efficient test method on site of the strong punned method in reinforcement of liquefied foundation, is suitable for the treatment of expressway.