Research On Transformation Of Axisymmetric Vertical Drains Into Plane Vertical Drains And Parameters Back-analysis Under Time-dependent Loading

Preloading with vertical drains is an effective technique for the soft ground treatment. Some new problems appear with the increasing popularity of installing vertical drains, therefore, developing more efficient calculation methods to analysis the behavior of sand drained ground plays an important role both in the theoretical and the practical sides of such problems.First, based on the progress made by former scholars, consolidation theories under time-dependent loading for sand drained ground and sand wall ground are reestablished respectively in this thesis. Solutions under single ramp loading and muti-ramp loading are respectively obtained. And the characteristics of consolidation by vertical drains under single ramp loading, muti-ramp loading and instantaneous are analyzed. The effect of loading time, well resistance, smear and vertical seepage are discussed in detail.Then equivalent transformation under time-dependent loading was deduced by matching the horizontal average degree of consolidation for sand drained ground in axisymmetric condition to the counterpart for sand wall ground in plane strain condition.Consequently, according to the equivalent transformation above, this thesis couples the Biot consolidation theory and optimization method, and initially establishes a method which suits for sand drained ground consolidation back-analysis and distortion forecasting, and also establishes corresponding computer program.Finally, according to the equivalent transformation in this thesis, a project example's data is used to carry on the back-analysis. The parameters that calculated by the program tally with the rule which consolidation process goes on. And the error between the calculated displacements and the measured displacements is small. The forecasted displacements calculated by the parameters back-analyzed are also tally with the measured displacements. It is proved that sand drained ground consolidation back-analysis method which this thesis proposed is quite successful and effective.