Study On Horizontal Bearing Characteristics Of The Caisson Diaphragm Wall With Variable Cross-section As Bridge Foundation

The caisson diaphragm wall foundation is a new type of bridge foundation,and it had good integrity and was already used widely in Japan.Although application of engineering example was little,it was got more attentions by a large number of scholars,especially the bearing mechanism of caisson diaphragm wall.Based on the caisson diaphragm wall,the caisson diaphragm wall with variable cross-section was made optimization and improvement and kept the very good prospects for engineering applications.Currently,there was no report about the caisson diaphragm wall with variable cross-section,so the application and research of was just getting started.Therefore,this paper first to variable cross-section to connect wall of indoor model test of qualitative analysis to study the load-bearing characteristics under horizontal load.Then,using FLAC^3D numerical simulation to replenish and validation test results.And respectively discusses closed period of high walls and open width of variable cross-section to the wall,and the influence of different geological conditions of variable cross-section shaft type even horizontal load-bearing characteristics of the wall,and finally put forward suitable for calculation of variable cross-section shaft type.The following results were obtained:?1?The S_h-H₀ curve of the caisson diaphragm wall with variable cross-section are slowly,and the wall horizontal displacement as the wall increases with the increasing of the load.The ultimate bearing capacity depends on the horizontal displacement of upper structure allowed.At the basic level displacement allow,the caisson diaphragm wall with variable cross-section has a good bearing performance.In the same horizontal load,the displacement of pile group size and the diaphragm wall basic are different.Closure segment elevation is higher,the horizontal displacement is smaller,and the bearing capacity is better.The caisson diaphragm wall with variable cross-section shaft type to a point on the wall around the wall body with rotation,and based in the tilting damage characteristics.?2?The closing section of the wall higher,and the basic level displacement is smaller;Same horizontal displacement,the bigger the closure segments wall high,the greater load to subjected the wall.Closing the smaller period of highly variable cross-section of the wall,the wall of the medial and lateral friction exert more fully.Variable cross-section to the wall to wall body depth,must be the same closure segments wall high case.The same load,the wider open section of the wall,the displacement of the foundation level is smaller;The same horizontal displacement,the wider open section of the wall,the greater the subjected to the wall of the load.Different closed period of highly variable cross-section to the wall,the wall lateral soil resistance distribution of basic same,especially on the front wall of the lateral soil lateral soil resistance performance of the more obvious.?3?In the two kinds of typical geological model,the soil strength parameters variable cross-section influence the level of the wall bearing properties,especially within the wall body on the lateral soil resistance and wall body inside and outside the influence of friction resistance.In geological model of a situation,increasing the width of the opening paragraphs than closure segment height more can effectively improve the horizontal bearing capacity;Closing section of the increase of height of the wall to the inside wall body friction play is limited,and wide open section of the wall increase internal friction play a bigger effect.In the geological model of the two cases,increasing the width of the opening paragraph and closure segment height can effectively improve the horizontal bearing capacity;Increase the closed period of the height of the wall is not conducive to the inside wall body frictional resistance of the play,and increase the width of the opening paragraph,the inside of the wall body friction play more fully.?4?By theoretical analysis,and can got the suitable for variable cross-section shaft type horizontal bearing capacity calculation method of the caisson diaphragm wall with variable cross-section.Analysis the horizontal bearing capacity calculation method and the numerical simulation results,and determine the level of the variable cross-section shaft type underground continuous wall bearing capacity of the value of safety factor for approximate calculation method.