Research And Analysis On Design Of Centrifuge Model Test Of Drainage Consolidation And Mixing Method

The capacity and the settlement is the main problem of building highway on soft ground of deep saturation. For this question, it proposes a method which using long plastic drain board and the short cement mixing pile to deal with it. This method is called Drainage Consolidation and Mixing method for short (D-M method). In the D-M method, short piles provide more bearing capacity and foundation stability. And the vertical displacement hull accelerates the consolidation of consolidated zone and unimproved zone. This method yield good economic returns.To further understanding the mechanism of the law reinforcement, nine centrifuge model test programmes are designed for different length of pile and board, different rate of replacement, dealing with single mixing of drainage method. One of the centrifuge model test programmes is carried out on Tongji University's TLJ-150 centrifuge to prove the reasonableness and feasibility of the design program.To meet with the requirements of Geometric similarity, Campaign similarity and Mechanics similarity to the Prototype, it uses the theory of the centrifuge model's consolidation time is 1/N2 time of Prototype's. Cement mixing piles is replaced by precast piles. Plastic drain board is replaced by wool. It simulates the top additional load by the force of surcharging roadbed and hydraulic jacks. Change the force of hydraulic jack to simulate the dissipation process of Excessive-pore water pressure during graded Construction of roadbed, surcharging and operation.Collecting the date of stress of piles and soil, settlement, excessive pore water pressure is deal with by Measuring Real-Time Processing System. The law reinforcement of D-M method is studied by choosing a reasonable Analysis Method and test date.The result that is listed above proves the design of the centrifuge model test programmes and the method for analyzing the results of test is reasonable and feasible. It is a reference to the tester who does the similar job. The result of centrifuge model test gives the reaction to the following basic characteristics of composite foundation:1. There is difference between the settlement of pile and soil. By the compatibility of deformation, the capacity of soil increases, at the same time stress concentration of pile alleviates.2. The settlement of centre ground is the biggest. The horizontal displacement occurs in base of slope.3. The rate of discursive of excess pore water pressure: composite zone >consolidated zone >unimproved zone4. The reclamation of subgrade generate the swell of groundIn the end, the problems concerned in this dissertation requiring further studies are discussed.