Study On The Plastic Drain Board Method Handling Soft Soil Subgrade

In the engineering construction of the road, we often meet the condition of soft soilsubgrade. The characteristic of the soft clay produces a great deal of questions of theembankment steadily or too big settlement etc while building the highway. It causes thehighway to be destroyed or can't be used normally. The plastic drain board is one ofeffective methods of handling soft soil subgrade. The plastic drain board method appliesextensively in recent years in China, but the theory of the consolidation and settlementwill be further studied. For example, the settlement and the consolidation degree iscalculated complicatedly. Especially there is less large-scale numerical simulation. Allvarious kinds of computing technology make simplify to actual conditions, thecalculating amount is reduced, but the calculating value differs greatly. The finiteelement analysis has problem of the model and the parameter at theory probing intostage. The optimal design with the plastic drain board is problem remaining to besolved.This text introduces the classification and structure, project characteristic andmechanics characteristic of soft soil and the danger and handling of the soft soilsubgrade. The paper narrates the principle of the plastic drain board method to deal withsoft soil subgrade. It increases soil layer the way to drain off water, shortens the distanceof drain off water, produces additional stress at load function, makes moisture throughinsert water drainage board in soil layer discharge, accelerates the consolidation andsettlement of the ground, bears the weight of strength, guarantees the purpose withsteady road bed in order to achieve and improve the ground. To introduce plastics drainboard's performance and classification and scope of application and improvementsubgrade construction craft. Then explaining the theory formula for the subgradesubsiding. It includes divide layers of total law calculate final settlement severalformula and Terzaghi consolidation theory formula and Barron degree of consolidationformula and total average consolidation degree formula and calculating permeatecoefficient of the multi-layer soil formula. To sum up the theory formula for theconsolidation and settlement of the instantaneous and step by step to add load,plasticsdrain board's length and well resistance and daub function. Especially to apply theoryformula calculating the consolidation and settlement of the highway subgrade throughthe plastics drain board preloading before and after in build urban, Harbin. To choosethe representative area lists the data. To utilize SUFER mapping software of the projectto draw the isoline chart of the consolidation, curve graph of the subsiding amount.Through comparing and analysis, reflect the validity of the plastics drain board dealingwith soft soil subgrade. Comparative analysis the reinforcement result of theinstantaneous and step by step preloading and the state of setting up the plastics drainboard (different spacing or different length). It has offered the objective basis for theresearch and analysis of the subgrade settlement and the consolidation steadily further. On the basis of the information of various fields reconnaissance, designing andconstructing etc in studied area, consulting a large amount of about monograph andthesis and specification, the paper proposes to calculate and analysis the plastics drainboard handling with soft soil consolidation and settlement by the ABAQUS finiteelement software. ABAQUS is a set of powerful simulation software of project based onfinite element method. It can solve such various kinds of problems with the simplelinear analysis and non-linear simulation. ABAQUS finite element software postprocess is powerful, can output the isoline, curve graph, still can show dynamically.This software can consider the viscosity and elasticity and plasticity and permeability ofsoft soil while calculating the soft soil subgrade, set up continuation plane strain model.Appling the Terzaghi –Rendulic consolidation theory and the penetrative coefficient...