Application Of Plastic Drainage Board Preloading With Dynamic Compaction Soft Foundation Treatment

The coastal urban areas widely distributed in the deep Marine sedimentary soft soil,mainly for the mud and silt soil, its main characteristic is big water content, large void ratio,low strength, high compressibility, and has significant thixotropy, special engineeringproperties, such as creep poor engineering geology conditions, regional obvious. Therefore,in the engineering construction in the coastal area, often bearing capacity of soft soilfoundation is far lower than the design requirements, need for reinforcement of soft soilfoundation. Stack preloading method can improve the bearing capacity of soft soilfoundation, decrease the settlement of foundation, but long treatment period, high cost;Dynamic compaction method has some advantages such as simple construction, low cost,good effect, but in the treatment of the saturated soft clay prone to\"rubber soil\"phenomenon. In recent years, the geotechnical workers will stack preloading combiningwith dynamic compaction method, it is successfully used in coastal soft soil foundationreinforcement, formed a new kind of foundation treatment technology. Practice shows thatthis new process is very effective for dealing with saturated soft clay foundation. But, atpresent the theoretical and experimental study of this kind of joint reinforcement method isfar behind the demand of engineering practice, there is no mature design theory and designmethod, the reinforcement mechanism and design theory there are many ambiguities, tosome extent, restricted the popularization and application of this new method. Therefore, inthe direction of theoretical and experimental research has important theoretical significanceand practical value in engineering.Fuzhou Baling200,000tons of caprolactam project, which is typical of coastal softground, soft ground to increase the permeability of the drainage path by shortening theplastic drain board set up to fight in order to expedite the process of preloading thefoundation of drainage consolidation. Then, using dynamic compaction furtherreinforcement, good compaction process to avoid the emergence of "rubber soil"phenomenon. In preloading, compaction two-stage process to develop a morecomprehensive test monitoring and testing program was completed. By drilling andsampling, conducted soil tests related to indoor; while using the in-situ testing methods,such as the vane shear test, static cone penetration tests, etc., and were stratified surfaceand soil subsidence observation, deep horizontal displacement observations and porewater pressure observation. In addition, the paper also uses MIDAS GTS NX software forgeotechnical and tunnel preloading process simulation analysis. Through theabove-mentioned results of laboratory and field test and simulation collation and analysis of the law reveals the growth and foundation reinforcement dissipation of pore waterpressure in the process, such a joint working mechanism of coastal Reinforcing Soft on;verify this joint construction method for ground deformation and bearing characteristics ofthe treatment effect; compaction degree of consolidation after calculating the amount ofcontrol and rammed Shen were analyzed, draw some useful conclusions.1） soft ground settlement variation with time that the initial loading largesettlement,settlement rate, slowing down until the final conclusion of convergencepreloading of settlement; monitored by the layered settlement drawn mainly from thesettlement of silt sedimentation layers, in the lower part of the settlement also accountedfor some components, to achieve the desired treatment effect conclusions.2) In the preloading phase through the pore water pressure monitoring, obtainedvariation of pore water pressure that the initial loading large pore pressure increase,growing faster, preloading of pore water pressure dissipation rate slows and trends stableconclusions3) In the compaction phase rammed by clicking Shen amount of observational resultsshow that the total amount increases Shen tamping tamping hit number increases, theincrease rate.4) In the compaction phase through the pore water pressure monitoring results showthat soil compaction so that the rapid increase in pore water pressure, pore pressureaccumulation, while laying drainage system makes tamping soil mass in the pore waterpressure can promptly dissipated.5) In the compaction phase before and after compaction by static cone penetrationand in situ load test results show that the dynamic compaction so crusty layer of soilformation and the scope of this article crusty layer body was about Turkey, but also strongrammer can well reduce the settlement after and after plastic drainage plate bearingcapacity of soft soil compaction preloading after treatment has been significantlyimproved.In addition, the paper consolidation of existing theories and methods of computationof sand drain foundation for a more comprehensive summarized and analyzed.