Research On Design Theory Of Anchored Soldier Pile And Lagging Wall For High Embankment Based On Structure-Soil Interaction

Anchored soldier pile and lagging wall consisting of pile, ground anchor and concrete lagging is a new type of retaining wall to retaining high fill embankment. Compared to cantilever soldier pile and lagging wall, load bearing of pile is greatly improved and the wall became higher than other type wall for the usage of anchor. With significant technical and economic advantages, this structure has been widely used in freeway, rail way construction and water conservancy project. But the theoretical research of the structure is far behind of its engineering application, Anchored soldier pile and lagging wall damage occurs at times for improper application. On this background,a systematic study of the structure was made in this paper . The working mechanism and the mechanical properties of this structure were studied. Then the mechanical model was erected based on structure-soil interaction and a more rational, suitable calculation method was proposed. The achievements of the study on the structure have significant theoretical and practical value for further application of the wall in the future.First of all, through briefly analysis of the structure, the working characteristics of the each component of the structure was discussed. It was recognized that the final inner force and displacement was influenced by the process of the construction, namely the different case conditions would result in different inner force and displacement. Based on the soil-structure interaction, the mechanical calculation model of different construction stage was established which can calculate the change of structural reaction. The new Calculation method named "incremental method" was proposed.The results of two filed test with different geologic conditions were analyzed and the characters of the structure reaction during the construction process was studied. Consequently, the change law of the pile inner force, displacement and anchor force was emphatically analyzed. The results of field tests also demonstrated that final inner force and deformation of piles was closely related with construction processes. It was confirmed that the pile-soil system was in good accordance with beam on vertical elastic Foundation model characteristics by the conformance between datum from test and results from calculation of model of the beam on elastic Foundation when anchor stressing. Results of the two field test demonstrated that the structure under different geologic conditions have different behavior.The 2D analysis of one of field tests work was conducted by ABAQUS FEM software and its construction processes was simulated to study the reactions of the structure and backfill. The simulation results showed that the stress state of backfill was changed and its sustainable development of the plastic zone of the backfill was constrained once the anchor was locked-off. The development of new plastic zone of subsequent filling would start at the locked-off plane.On the basis of the field test and numerical analysis conclusions,the distribution of the earth pressure in each stage was put forward and the complete calculation process of the incremental method was given. Then one of field test wall was calculated by the incremental method and the good agreement between the tests results and calculation result proved the correctness of the incremental method proposed in this paper. For the value of the anchor force, it was suggested that the total pull force can be determined by (0.4~0.7) E0 according to different strata conditions. E0 stands for the general rest earth pressure.Finally, according to mechanical characteristics of different strata conditions, the basic design principles of the wall were presented, called "pile-soil stiffness matching" design method. When the stiffness of the strata where the pile was embedded is weak, the weak stiffness of the pile and more anchors should be taken. Otherwise, the strong pile should be designed. Furthermore the design process and steps of anchored soldier pile and lagging wall was summarized and an application of the wall for high fill embankment in some freeway was introduced for future reference as well as a damaged anchored soldier pile was analyzed. Lessons and the points for attention to be drawn for the future design.