Research On Design And Construction Technology Of The Composite Foundation For Anchor Of The Humen Second Bridge

In bridge construction field,Gravity anchors are usually applied for the common structure of suspension bridge.The foundation pit enclosure structure in which underground diaphragm walls are applied,functions as water severance,seepage prevention,load bearing,water defence.Compared with other enclosure structures,underground diaphragm walls can reduce construction cost efficiently and its application presents in series of bridge construction fields under the improvement of modernization of engineering and construction process,large scale of constructions;it is prospective.Though traditional underground diaphragm walls consists of walls,inner linings,bottom plates and apical plates,its walls and the inner linings are long-bar implanted reinforced-concrete structure;walls and inner linings are connected with common straight threaded rebar connector;bottoms plates and inner linings are bound with reinforcement,ranged at 10cm~20cm and implanted in inner linings.Walls,inner linings and bottom plates are not integrated together.Therefore,the places,the interface between the forehead walls and the bed of bottom plates,the rear walls and the cap of bottom plates,are inclined to be rotted and cracked.Given this,underground diaphragm walls are not considered as a part of permanent force.This article has summarized the research about the key technology of composite anchored foundation under flow plastic silt cover layer,through examination of long-span suspension bridge—Humen Second Bridge Project,and integrating the underground diaphragm walls and gravity anchors together as a whole force-bearing architecture.The main research about excavation of composite anchored foundation are list below.(1)Based on the object,the anchored foundation of Humen Second cyclopean suspension bridge,the research about the rule of loading distribution among underground diaphragm walls and bottom plates and the influence of the parameters to loading distribution has carried out;compared the mechanics performance and stability of foundation when the composite effect of underground diaphragm walls is considerate and not;analyzed the suitable working condition when underground diaphragm walls,inner linings and anchor function collectively.(2)Considering characteristics of the flow plastic silt cover layer in this project,the analysis on choosing the suitable underground diaphragm walls devices,controlling the performance norm of slurry and the quality of mining joint construction has been commenced;the research about the construction process of underground diaphragm walls has been carried out anew,summarized the pivotal technology of composite anchored foundation and underground diaphragm wall under flow plastic silt cover layer.(3)Through the numerical simulation intimating the super-vast underground diaphragm walls foundation support system,accomplished the formal analysis,revealing the process of excavating soil and building inner linings in foundation,offering the basis to construction;(4)Bound with results of numerical analysis,commenced the research about construction process of foundation digging under flow plastic silt cover layer;raised proper digging method with the min cost and superior efficiency in foundation excavation under the composite consideration of safety of enclosing structure;summarized the construction process under flow plastic silt cover layer.