Study On Side Friction Characeristics Of Rock-sockted Piles In Red-sandstone Rock

In recent years, the rock-socketed pileshave been more widely used in red-sandstone region, and because fewer tests and measured data, the red-sandstone rock-socketed pile design is unreasonable. How to determine the lateral friction of red-sandstone rock-socketed piles has become an important issue of engineering.Therefore, further studying of the side friction of red-sandstone rock-socketed piles have an important significance of geography and practical engineering.The paper collected and studied the existing method to calculate the vertical bearing capacity by consulting the related literature which shows that the calculation method of the domestic and foreign literature and specifications are unreasonable to determine thelateral friction of rock-socketed piles in red- sandstone area, all of them do not consider the corresponding parameter, such as the initial stress, roughness, construction technology and other factors.Then, further research model test data, the result shows that: 1),the groundwater and sediment have a remarkable influence on the lateral friction of rock-socketed pile, lateral frictionincreases slowing down when the relative displacement of piles and rock range from 1 to 2mm, but does not appear strain softening phenomenon;2), because the value of khas a volatile region in red-sandstone areawhich proves the linear elastic- plastic model does not apply to the calculation for load transfer; Derived the lateral friction resistance calculation methods in red-sandstone region by usingthe slip- dilatancy theory and the theory of computation rock strength, and it can better matched bycomparing with model test data.Finally, using Flac3 D software to simulate the piles according to themodel.Simulating the pile-rock interface friction characteristics in various states which contained water environment, different pile diameter, embedded in different depths and different sediment situations,the results shows that: the best rock-socketed ratio is 1:5 in red sandstone area. The main section of the pile to play rock pile side resistance and relatively displacement concentrated in 0.5D ~ 1.0D of the pile; compared with the same rock-socketed ratio, side resistance and pile side load sharing ratio does not increase when the pile diameter increases, when the rock-socketed ratio is relatively small, there will show pile tip enhancement effect, with the rock-socketed ratio increases, this effect will gradually disappear. Pile side friction under groundwater can be calculated as 0.88 times when the pile isn’t in groundwater environment. Mechanical properties of the pile bottomsediment is poor, after loading on the pile, the relative displacement of the rock-pile will develop fast, so the sediment of pile bottom should be thorough clean. By comparing the play speed of pile side resistance of model test and simulation test, which proposed the quality indicators and integrity of rock has a significant impact on rock pile lateral resistance.