Study On Effect Evaluation Of Static-Dynamic Drainage Consolidation Method For Strengthening Soft Foundation

The evaluation of whether an engineering project the construction of a building is qualified for it to meet the service property or not depends on the quality of its soft soil foundation reinforcement, that’s why in recent years, the evaluation of soft foundation reinforcement has gradually been valued by people. Scientific and objective evaluation of soft foundation reinforcement effect can not only bring economic benefits, provide the basis for the control of the construction progress of the project, can more objective understanding and a better understanding of the reinforcement mechanism, but also of similar soft soil foundation treatment project has the significance of reference and guidance. Therefore, it is of great theoretical significance and practical value to improve the scientific and technological level of soft foundation treatment.Static-dynamic drainage consolidation method (SDDCM) is one of the soft soil foundation reinforcement technology developedin recent years,and it is more widely applied. At present,the effect evaluation of this method is still stuck in the level of referencing other reinforcement methods and adopting empirical methods, so the way to correctly understand and scientificly and objectively evaluate the reinforcement condition of this method becomes an important realistic meaningful problem and should be solved urgently.In this paper, firstly, the research status of the commonsoft foundation reinforcement method and effect evaluation has been summarized, and the research status and strengthening mechanism of static-dynamic drainage consolidation method are briefly introduced. Using the independent researched equipment the second generation multiple high speed impact intelligent control instrument to modelize the static-dynamic drainage consolidation reinforcement method insoft soil model test. By analyzing and comparing the experimental data of pore water pressure, soil pressure and settlement, to explore the effect of static-dynamic drainage consolidation method in different construction scheme conditions of soft soil foundation reinforcement; the static-dynamic drainage consolidation method and inserting plastic drainage plate preloading method are applied on the actual project contrast to compare the reinforcement effect of these two kinds of soft foundation reinforcement methods. And in order to more conveniently, more economicly and more efficiently evaluate the soft foundation reinforcement effect, the relationship formulation of the cone penetration test and vane shear test parameters try to be established and an applicable computer calculation programtry to be developed. The main results are as follows:1、The basic methods and indexes of soft foundation treatment effect evaluation are analyzed, and the basic evaluation method and index system of static-dynamic drainage consolidation method are put forward.2、The soil settlement set by static-dynamic drainage consolidation method is 10cm larger in shallow layer (buried deep 2m),5 cm larger in middle layer than it set by inserting plate preloading method, while the soil settlement in deep buried layer(buried deep 6m and below) is similar.The total settlement of the former is much larger than the latter, which primitively verified under the condition of static-dynamic drainage consolidation method of soft foundation construction has a better reinforcement effect.3、By analysing the pore presure data during the tamping process, some conclusion can be gained.The deference of pore presure in shalow layer of the soil caused by the first time tamping of SDDCM is 9.9kPa larger than it is caused by inserting plate preloading method, while 9.1kPa in the deeper layer(buried deep 4m),which shows that static-dynamic drainage consolidation method applied to the stage in the soil was significantly greater than that of inserting plate preloading method. However, after construction, the pore pressure of the former is smaller than the latter, which shows the advantage of the former again from the angle of the consolidation of the stress expression.4、By using the cone penetration test is to know that during the static-dynamic drainage consolidation method construction the soil strength can be improved by every time of tamping, the compaction degree of soil in 3.5m depth increased tremendously, the average cone tip resistance tested after the construction reached 10 times than it before, meaning the reinforcement effect is significant. At a distance of 10m to the muck surface, the cone tip resistance was up to 4.0 times higher after the reinforcement than it before, which meansthe reinforced depth of static-dynamic drainage consolidation method is more than 10m, tamping energy can also be transfered to the deeper soft soil, indicating that the reinforcement depth is deep and can reinforce the deep soft soil foundation.5、Through the vane shear test is to know that, undisturbed soil and remolded soil shear strength are greatly improved after tamping. The average shear strength of undisturbed soil after the reinforcement is 5.0 times for it was before; remodeling soil shear strength average is 3.8 times for it was before the reinforcement; meanwhile, the sensitivity of soft soil significantly reduced whick indicates that static-dynamic drainage consolidation method does make the high moisture content muck soil density and strength improved.6、Established a relation of the cone penetration test and vane shear test parameters, in order to provide an effective method to solve problems as saving the high cost of testing, especially owing to the limitation of site conditions and difficulties to test certain mechanical quantities. And successfully developed a CPT parameters and elastic parameters and strength index relation theory analysis and calculation computer program. The cone penetration test and vane shear test parameter of program analysis and calculation can provide efficient and convenient tools to test in geotechnical engineering and soil assessment.