One-Dimensional Consolidation Theoretical Analysis As Well As The Prediction Of Consolidation Coefficient And Their Visualization

Consolidation settlement means the soil compacted, the water released in the soil and the pore water drained gradually under additional stress. Not only should we determine the deformation quantity of ground foundation during the construction or after the construction, but also should we consider the ratio on the bottom of the subgrade during the settlement, so that we can control the schedule of construction and take measure to the non-homogeneous settlement of the buildings. Therefore, we should fully consider the influence of consolidation time and consolidation settlement.In the real formation, the water released according with two-dimensional or threedimensional consolidation theory. However, the theory of 2-D or 3-D is complicated, the parameter is difficult to determine and the solution is complex. So, this theory is hard to be accepted by the researchers during the construction. Although Terzaghi one-dimensional consolidation theory has amounts of assumptions, this theory is conciseness, the solution form is simple and it has full of engineering experience in many years. So, Terzaghi one-dimensional consolidation theory is still the recommend calculation method of current criterion. Therefore, it has powerful vitality.Based on the analysis above, in this paper the main research are as follows: Modified the assumptions of Terzaghi one-dimensional consolidation. Deducted and constructed the internal equations and semi-permeable boundary equation of different complex situations. Considering the non-homogeneous of soil, we use formula method and support vector machine method to calculate the consolidation coefficient respectively. Meanwhile, we realize the visualization of interface introduced above. Finally, we contrast the results which are calculated by the developed interface and the data collected by the sensors of the physical model test. The specific analyses are as follows:(1) Modified the assumptions of Terzaghi one-dimensional consolidation theory. Given the theoretical analysis of the following situations: external load increased with time, foundation soil stratified, the thickness of foundation soil increased, the foundation soil stratified under external load increased with time and the thickness of foundation soil stratified and increased. Meanwhile, we set up the internal equations of different situations mentioned above.(2) Modified the boundary condition of Terzaghi one-dimensional consolidation theory. Based on the expressions of semi-permeable, we use Taylor series expansion to reconduct the difference form of semi-permeable boundary equation which has second order accuracy. The conducted boundary revise the situation of Terzaghi one-dimensional theory which can only calculate permeable and impermeable extreme boundaries. Contrast the difference solution and the theoretical solution which took homogenous foundation for example, the results show that the difference solution satisfies the precision of engineering.(3) The permeability consolidation test and the normal soil test. We obtain the osmotic oedometer which can carry on consolidation test as well as permeability test by refitting the traditional oedometer. We take this instrument to conduct the permeability and consolidation test using silt and sand soil samples. Then we use formula method to calculate the consolidation coefficient. This method can avoid error which is caused by the human factors and test methods using traditional consolidation coefficient determination method. In addition, we determine the gradation indexes such as effective diameter d10, limited diameter d60, continuous diameter d30, non-uniform coefficient Cu, curvature coefficient Cc and the physical indexes such as soil nature density ?, moisture content w and specific gravity of soil ds.(4) Determination of consolidation coefficient. The consolidation coefficient through permeability and consolidation test can be seen as the measured values. To regard the soil parameters which are obtained by the normal soil test as influencing factors of support vector machine(SVM) and BP neural networks, then we use these two methods to predict the consolidation coefficient. Besides, we contrast the predictive values and the measured values. The result shows that the prediction accuracy of SVM is higher than BP neural networks’ and the stability of solution is better.(5) Interface realized. We develop these five complex conditions interface under semi permeable boundary and the consolidation coefficient prediction interface which based on the platform of MATLAB. Moreover, considering the non-homogeneous of soil, we apply the prediction consolidation coefficient to the complex conditions interface. Finally, we realize the interface which reflected dissipation of pore water pressure and the computing of average consolidation degree under semi-permeable boundary, variable consolidation coefficient and different complex conditions. The visualization of these interfaces can be used more convenient by the researchers.(6) Example verification. We regard the indexes of physical model test soil as influencing factors, and then predict the consolidation coefficient along with depth and the permeability coefficient of bottom using SVM. We calculate the pore water pressure at any time using the interface which is developed and contrast the measured data which is obtained by the pore water pressure sensors in the physical model test. The result shows that the water released regulation will be more realistic which considered the semi-permeable boundary and the consolidation coefficient along with depth.