Behaviors Researches Of T-shaped Cement-soil Deep Mixing Pile Composite Foundation Under Flexible Loading

With the rapid developing of our country’s infrastructure construction, more andmore highway will be building in soft soil foundation, which has brought newopportunities and challenges to soft foundation treatment technology. The compositefoundation have the advantages of good reinforcement effect, wide range applicationand low construction cost, which make it a best way to treatment the soft soilfoundation. And the T-shaped cement-soil deep mixed column is a kind of compositefoundation technology, and it has been well applied and promoted in many engineeringin our country.At present the relevant theory about T-shaped cement-soil deep mixing pile israther limit, especially there is little report about behaviors researches of T-shapedcement-soil deep mixing pile composite foundation under flexible loading. On the basisof previous studies, The thesis have done some targeted research about T-shapedcement-soil deep mixing pile composite foundation under flexible loading, such asbearing capacity and settlement. And the thesis mainly do the following works:(1) Combining with the Huang-E highway field load test, SPT, indoor unconfinedcompression test, To analyzes the test data and found that T-shaped cement-soil deepmixing pile has high bearing capacity, more standard penetration number and highunconfined compression strength. This shows that T-shaped cement-soil deep mixingpile have a good quality and a high strength, and is a good way to treatment the softsoil.(2) Based on the analysis of the test data, the thesis discussed the determinationmethod of the bearing capacity of T-shaped cement-soil deep mixing pile compositefoundation, after calculation comparison get the concluded that the best way todetermine the bearing capacity of T-shaped cement-soil deep mixing pile compositefoundation is according to the field test.(3) Through the embankment fill soil analysis modeling that consider theinteraction of inner and outer soil, get the calculation method of pile-soil stress ratio,and make a modify to the traditional displacement mode, then get a new displacement mode which can considered the distribution form of shaft resistance and the relativedisplacement of pile-soil interface, and used the “unit” analysis model, set up a Stressand strain coordination equation which can overall consider the interaction ofembankment fill soil, reinforced area in composite foundation and underlayer, and usethis equation deduced the T-shaped cement-soil deep mixing pile composite foundationarea reinforced decrement computing method.(4) Combine with the deformation characters of cushion material and underlayersoil when the pile penetrate the cushion and the underlayer, the thesis used expansion ofsphere cavities theory to analysis this problem, and consider the intermediate principlestress of the cushion and the underlayer, to established the sphere cavity expansionmodel based on unified strength theory. According to this modeling get the pilepenetrate settlement computing method, then to correction the settlement of thecomposite foundation reinforce area, to make the calculate result more tend to the actualdata.(5) Through to analysis of Huang-e highway field monitoring data, found T-shapedcement-soil deep mixing pile composite foundation can reduce the deformation of softsoil foundation effectively, and has a good bearing performance. At last, makecomparisons between the computing result based on the traditional composite modulusmethod, modified stress method, and the method get in this thesis with the observedsettlement data and the prediction settlement data. The comparisons result show that thesettlement calculation method get in this thesis is rationality.