Study Of Key Issues Of Stabilized Soil Mass By DMM Applied In Port Engineering

The Deep Mixing Method(DMM),a deep in-site stabilization technique using cement slurry as a stabilizing agent and installed by a variety of patterns,such as block type,wall type,grid type,or group column type and so on,is applied for improving the bearing capacity of foundation as a whole or composite foundation and/or reducing settlement,and also can be used for sealing up.This method has advantages of a short duration,high design strength,small settlement,wide range of applications,no pollution,and more effectively using resources.In China,it has been widely installed underneath a road embankment or around dwellings on land.In comparison,it has only three applications for port facilities because of high cost and shortage of construction technology.In the thesis,two key issues of stabilized soil mass with DMM has been discussed because of effective application and promotion of DMM in port engineering.Firstly,it is about height of rubble mound.In Technical specification for Offshore Cement Deep Mixing Technique to Consolidate Soft Soils,there is a provision that the height of the rubble mound on the mass should not be more than 1.5m when DMM is applied for gravity structure in port engineering,and there is no detailed explanation in the code.In the thesis,the sliding failure modes and calculation theory of rubble mound beyond fixed type and floating type stabilized soil mass has been analyzed.And the limit of the height has been ensured in the two types.Then,stability of rubble mound beyond stabilized soil mass by DMM has been studied by physical model test,based on the wave sump in Port Engineering Laboratory,Hydraulic Engineering College,Dalian University of Technology.In the physical model test of wharf section,the effects of porosity,height,friction angles on the stability of rubble mound on fixed type and floating type has been discussed respectively.And the correctness of the calculation theory has been verified.In model test,non-contact measurement methods,laser displacement meter and PIV technology and DIC technology,was used to analyze the data.The macroscopic and microscopic movement of particles in rubble mound was discussed.Theoretical analysis and experimental study show that structure meet the safety requirements,when the provision of rubble mound height in the specification has been exceeded.As a result,it will efficient cost savings.Secondly,field strength of stabilized soil has been analyzed.High pressure injection deep mixing method has less experience in port facilities,we must test the strength of the different age to determine the design strength standard values.In the thesis,the non-linear function,Slogistic1 model,between the period and the unconfined compressive laboratory strength of stabilized soil has been fitted,and that between the period and field strength has been fitted,too.And the relationship between lab and field strength has been researched.Accordingly,a formula to prejudge 90 d field strength is obtained according the laboratory strength in 28 d,65d and 150 d and the field strength in 24 d and 44 d.This approach takes into account the relationship between laboratory and field strength to calculate and is more convenient in QC/QA.In this paper,the author use theory,experiment and large data method to study the crucial issues on DMM application in port engineering based on a certain project.This plays an important role in the application of DMM in port engineering.