Soft Rock Foundation Of Large Diameter Rock-socketed Pile Bearing Performance

With the rapid development of large-scale urban and infrastructureconstruction, rock-socketed piles have been widely used by reasons oftheir high bearing capacity, small settlement, simple construction andgood anti-earthquake property. But the bearing machanism of rock-socketed pile has not been understood thoroughly, especially the bearingproperties of the large-diameter and medium-long socketed piles in softrock foundation. The current design methods are still different from thereal bearing machanism and need to be developed.Based on the prototype observation of the piles foundation under thebridge of Du Kou river in Yichang-Wanzhou railway, the bearingproperties and load-transfer machanism of large-diameter rock-socketedpiles in soft rock have been studied in this paper, used the method whichcombined in-site test data with the numerical simulation. The mainconcerns of this paper are as follows:(1)The present research on the bearing behavior of rock-socketedpile is stated, include the research method and production; also, a briefintroduction is made about the concept and sort of soft rock.(2)The basic bearing and deformation characteristics of the rock-rocketed piles are analyzed thoroughly, and then the factors influencingthe bearing capacity of rock-socketed piles are found out.(3)Prototype observation of rock-socketed pile in soft rock isconducted, and a large number of new in-site test data is presented. Basedon these data, the law how initial strain changes before loading isanalyzed, also the bearing properties and load-transfer machanism of rock-socketed piles in working condition are analyzed, include the distributionof axial force, the side resistance of piles and the characteristic ofload-settlement curve.(4)The rock mass's deformation behavior and some famousconstitutive models are introduced. The advantages and disadvantages ofthese models and their applicable conditions are described generally.Especially, the D-P elastic-plastic model which this paper adopted isexpatiated thoroughly. (5)3-dimensions elastic-plastic finite element model of rock-socketed pile is established. The bearing properties of rock-socketedpiles under vertical loading are simulated, and compared simulate resultwith the in-site test data; the factors influencing the bearing properties ofrock-socketed piles are discussed, such as the length and diameter of pile,elastic modulus of pile and elastic modulus of rock.Some valued conclusions are obtained in this paper, which can offerreference to the design and construction of the rock-rocketed piles.