Research On Integrated Ground Improvement Technique For Large Storage Tank Under Complicated Soft Foundation

On the basis of introduction to large storage tank foundation type and ground deformation for petro-chemical enterprise, the article makes deep theoretic research of enforcement mechanism, property of force, bearing capacity and settlement calculation for the complicated soft foundation improvement method which is combined with vibration crushed gravel, cement flyash gravel, plastic drainage sheet and full of water-prepress, and inspect the improvement effect by multiway such as indoors test, cone penetration test(CPT), dynamic penetration test (DPT), plate load test. In the end an example is given to expound the construction , monitoring of large storage tank. Following are conclusions:1. The integrated ground improvement method has academic basis, and the effect is reliable through practice, it can effectively improve the foundation intensity and stability, and also reduce settlement and uneven settlement, the method has instructional significance foe large tank construction in yellow river delta.2.The main function of vibration crushed gravel is to squeeze soil, eliminate earthquake liquid and debase liquid grade, it also enhance the property of soil drainage, spread consolidation, improve compressibility and shear strengh. The extent rests with the soil type.3. As a kind of rigid pile, CFG has the characteristics of higher pile capacity, deeper load transfer, it can greatly reduce settlement, save time for full of water-prepress.4. Plastic drainage sheet is an effective method to spread soil consolidation, it alsocan anti-slide.5. Full of water-prepress is an important method to increase the capacity of composite foundation, it can also make tank foundation settle in advance, reduce the deformation in use. The pre-press load should be determined by calculation.6. Constrction monitoring shows that soil pressure is not even for large tank, so it is not recommended to design by average soil pressure. The permeability has significant effect on the ascend and fall of pore water pressure, the distribution has great ruling in horizontal and vertical space, the pore water pressure in center of tank is higher than that in tank edge, and upper soil pressure is higher than that in lower soil.7. It is not necessary to reach the capacity value demanded by design unit, strength increase should be considered after finishing full of water-prepress process so as to reduce ratio of replacement and project costs.