Analysis Of Stress Performance Of Pre-stressed High-strength Concrete(PHC)Pipe Piles In Liaoshen Region

Because of the Pre-stressed High-strength Concrete pipe piles have many advantages, such as high vertical bearing capacity, reliable quality of pile driving, less pollution to the environment and so on. Now it’s widely used in Liaoshen regions. With regard to the pile foundation, due to the different circumstances of each region, the determination of the vertical bearing capacity will be different. When there is an appropriate method to determine the vertical bearing capacity of Pre-stressed High-strength Concrete pipe piles for this region, it will have great significance for the Pre-stressed High-strength Concrete pipe piles’promotion in this region.This article used numerical simulation software FLAC3D to simulate the bearing mechanism of Pre-stressed High-strength Concrete pipe piles in this region. By comparing the results of simulation and pile static load test, stress mechanism, load transfer, changes of lateral friction resistance and tip resistance of pipe pile were analyzed. The soil plug effect of opening Pre-stressed High-strength Concrete pipe piles was analyzed too. By analyzing the influence factors of soil plug effect—pile length, pile diameter, properties of pile tip soil, soil plug length—to determine the influence coefficient of soil plug effect, which has influence on opening pipe pile, and we call the influence coefficient as a.Through the results of the numerical simulation of Pre-stressed High-strength Concrete pipe piles’bearing mechanism, we could find that it’s better to use FLAC3D to simulate the vertical bearing capacity of Pre-stressed High-strength Concrete pipe piles. The load-settlement curve obtained by simulation is similar to the results of pile static load test. Through the analysis of lateral friction resistance and tip resistance of pipe pile, we can conclude that the lateral friction resistance of pipe pile has not been increasing as the load increases. When the load on the pile top reaches the vertical bearing capacity, the lateral friction resistance of pipe pile will slightly decreased with the increase of the load. As to the tip resistance, before the load on pile top reaches the vertical bearing capacity, there are little changes for tip resistance. When the load on the pile top reaches the vertical bearing capacity, the tip resistance began to increase sharply. Through the analysis of soil plug effect on opening Pre-stressed High-strength Concrete pipe piles, we can see that the soil plug effect has great impact on friction pile, and has little effect on end bearing piles. The greater the intensity of the pile tip soil, the smaller the impact of soil plug effect on the vertical bearing capacity. The formula of vertical bearing capacity characteristic value of pipe pile was amended. The formula that is empirical, which is determined according to the relationship between the soil physical indicators and bearing capacity parameters. The result of the amendments involves two aspects. When the pile is closed pipe pile or the pile tip soil of opening pipe piles is high strength sand or bedrock, the calculation methods is still based upon the local standards of Liaoning Province. When the pile tip soil of opening pipe piles is clayey soil or silt, the calculation of lateral friction resistance of pipe pile should be multiplied the soil plug effect coefficient which is called as α. The soil plug effect coefficient is related with the properties of the pile tip soil and the value of soil plug effect coefficient is between0.7and0.9.