关键词: 嵌岩桩, 厚层沉渣, 承载力, 抽芯试验

Abstract: In situ core-drilling tests and static loading tests are carried out on rock-socketed pile. The test results show that when using the impact pore-forming construction and the upper part is a weakly cemented soil, pile bottom sediment thickness is generally larger, which is much thicker than the specified value by the foundation code. When the load reached a certain value, sudden and large subsidence is observed, because the end resistance does not take effect due to the existence of a thick layer of sediments. The test results indicate that the current design method of rock-socketed pile which considering both of the end and side resistance is not appropriate when impact pore-forming construction is used and there is weakly cemented soil around the pile. The bearing capacity of single rock-socketed pile should be determined by side resistance in soil and the socketed segment in rock. Numerical analysis is carried out on the distribution of side resistance of the rock-socketed segment and deformation and load carrying capacity of the pile. Under a given applied load, smaller settlement is observed when socketed thickness and rock strength is greater. With the increase of the applied load on pile top, settlement difference caused by the variation of socketed thickness and rock strength increases. The distribution of side resistance of the socketed segment along the vertical direction shows a double-peak saddle shape. When the socketed thickness and rock strength are smaller, the lower peak is higher than the upper peak. When the socketed thickness and rock strength are larger, the lower peak is lower than the upper peak. Under a given applied load on the pile top, smaller socketed thickness would result in larger settlement and side resistance. Due to the thick layer of sediment, the axial force of the rock-socketed segment of the pile gradually decreases from the applied load on pile top to zero along vertical direction, the smaller the socketed thichness, the faster the decrease rate.

Key words: rock-socketed piles, thick sediments, bearing capacity, on-site drilling test