The Study On Vertical Bearing Capacity Calculation Methods Of Rock-socketed Piles Based On The Load Transfer Method

Nearly twenty years, our country has always attached great importance to transportation infrastructure construction, bridge and transportation infrastructure of high cost, difficult engineering. Along with the progress of technology, the bridge span increases day by day, the load gradually improve, for the requirements of the foundation also increase, in many of the base form, rock-socketed pile due to the high bearing capacity, seismic performance is good, small settlement, construction is convenient and advantage in the bridge engineering in the wide application of fan. The load characteristic research and bearing capacity calculation method is also concerned. But as a result of the bridge pile foundation engineering in complex geological conditions, the ultimate bearing capacity of single pile is very high, the traditional static load test is difficult to achieve destruction, so that at present the load character understanding, as well as its bearing capacity calculation method are put in bigger difference. So further study of rock-socketed pile bearing mechanism, the paper proposes a kind of very convenient for engineering application of the bearing capacity calculation method, and has important theoretical and engineering practical significance. So this paper combined with the national natural science fund project "on top of the pile foundation pile settlement control the vertical ultimate bearing capacity of design theory research"(item number50878083) subject, to carry out in-depth study of the system.In this paper, at first the pile foundation were reviewed in this paper, based on the literature at home and abroad have comprehensive analysis and research the rock-socketed pile load characteristic, the impact of rock-socketed pile bearing characteristics of the pile rock relative displacement, socketed depth hr, pile diameter size d, the rock elastic modulus Er, pile rock interface roughness, pore forming method, the rock layer characteristics, the weakness lie layer or karst, the rock mass stress level and the analysis of the factors in detail.Secondly for rock-socketed pile vertical bearing capacity of the commonly used method to determine the comprehensive analysis, this paper proposes an improved load transfer model, the model is based on elastic-full plastic model, using Hoek-Brown strength criterion calculating the pile side friction resistance limit. The improved model considering the limit of the friction resistance of many factors:the pile rock relative shear displacement, rock single axis compressive strength and rock in depth, rock mass integrity, rock mass category, from the theory of elasticity-full plastic shear-displacement model perfect.Then based on the load transfer method, guide got can consider pile layered rock mass characteristics of load transfer analytical solution. According to the pile soil different transfer function, guide with different pile top load under the condition of single pile bearing capacity calculation formula, this method can give full consideration to the side of pile soil resistance and bottom resistance play degree, different load calculation of settlement value. And it can also make the big-diameter rock-socketed pile load displacement curve prediction of all, realize the pile top settlement control according to the vertical ultimate bearing capacity of pile foundation design.Finally through the living water river large bridge panel a socketed pile static load test of construction site, the pile soil resistance, rock-socketed period of frictional resistance and end resistance were analyzed, and the measured data of this paper rock-socketed pile bearing mechanism and bearing capacity calculation method is validated.