Research On Bearing Caracteritic And Design Method Of Rock-socketed Pile On Karst Region

Along with the transportation enterprise's rapid development in our country, the pile foundation is applied in the highway bridge day by day widely. many pile foundations are used in the karst area region, our country karst are widely distribution, when the pile foundation passes through this kind of local zone, because has project hidden dangers and so on last ten days of the dog-day period limestone cave, causes the pile foundation to be extremely sensitive to the vertical distortion, once presents the excessive distortion, the immediate influence tip of pile karst roof thickness's stability, the situation serious possibly causes the limestone cave collapse, which has tfatal harmed to the entire bridge building. Therefore, this article uses the theoretical analysis and numerical simulation method, pile load bearing mechanism and the design method to the karst area were carriedon the discussion, the main research work as follows:Firstly, inlaying the crag pile supporting capacity and the design method particularity in view of the karst area, analyzed the karst area to inlay the crag pile thoroughly in the horizontal load and under the vertical load function stress characteristic and the load bearing mechanism, to inlaid the crag pile the load transmission process, the pile side resistance and the tip of pile resistance each kind of computation pattern, the destruction character; Simultaneously discussed the karst area to inlay the crag pile tip of pile rock layer the stress characteristic and the failure mechanism, inlaid the crag pile for the karst area the reasonable design and the computation has provided the foundation.Nextly, introduced the Hoek-Brown theory of strength, infers through the transformation can consider that the rock mass quality the rock mass tensile strength, simultaneously considered the vertical stress the rock mass shearing strength formula, applies it in the foundation pile tip of pile last ten days of the dog-day period limestone cave rock layer roof security thickness determination, obtained the karst area to inlay the crag pile tip of pile limestone cave roof security thickness to determine the new method. it, analyzed the karst area to inlay the crag pile again the load bearing mechanism and the side anti- end anti- transmission rule, has established the pile side pile week load transmission model, in the load transmission theory's foundation, according to the pile side earth (crag) with the tip of pile rock layer resistance's display degree, led between the head of pile subsidence quantity and the head of pile load relationship, proposed inlaid the crag pile vertical supporting capacity computational method according to the head of pile subsidence control karst area.Then, the application numerical simulation method, analyzes under thoroughly the influence karst area pile foundation the limestone cave roof stable factor, the limestone cave distortion mechanics characteristic and the roof security thickness's influencing factor carries on the discussion to the different hole diameter condition, obtained the location limestone cave roof displacement change rule to dissolve, hole hole the principal stress change rule, in the limestone cave overburden along the vertical each principal stress change rule.Finally, the union actual project, inlaid the crag pile to the karst area the design and the computation has carried on the confirmation analysis, which has indicated the method rationality...