Research on Vertical Bearing Capacity of Single Bored Pile in Deep Soft Stratum of Hangzhou

The layers of a viaduct bridge construction site in Hangzhou are mainly clay,silt and silt sand.One group of the bored test piles with post pressure-grouting(a total of three piles) are designed to undertake the bearing behavior test by using single pile vertical static load test and high strain test to master the engineering properties in the viaduct bridge construction site.In-situ monitoring aiming at observing the pile shaft friction and pile tip resistance was conducted,in which vibrating wire reinforcement meter and sliding micrometer and earth pressure cells were adopted.After the test,the results of the data analysis show that the bored pile in Hangzhou soft soil works as the typical friction pile on force character.The measured data also indicate that the side friction resistance of the bored pile shaft gradually occurs from the top down to the lower part of soil layer,and the shaft resistance softening is observed when the load of the superficial part of soil layers reaches the ultimate shaft resistance.Furthermore,the results of the pile body high strain test are close to the results of the static load test,but the load proportion of pile shaft and pile tip has a little difference from the static load test.