摩擦型桩表面劣化时的沉降特性室内模拟试验

Laboratory model tests on settlement characteristics of friction pile with surface deterioration

为研究工作荷载作用下,摩擦型桩(端承摩擦桩和摩擦桩)在腐蚀地基中发生表面劣化时的沉降特性,通过制作以硫酸铜溶液为腐蚀性介质的饱和砂土地基模型,开展了加速劣化试验,得到工作荷载作用下摩擦型桩表面发生劣化时的沉降规律.结果表明:腐蚀地基中,桩表面劣化程度随时间不断增大,沉降量随劣化程度的增大而增大;端承摩擦桩和摩擦桩的荷载-沉降曲线发展规律不同;在工作荷载作用下,经过17 360 min,端承摩擦桩的沉降量达到桩径的28.5%,其中表面劣化引起的沉降量为10.6%,大于摩擦桩的7%;试验结束时,端承摩擦桩和摩擦桩的沉降量均达到了各自极限承载力对应的沉降量.表面劣化导致摩擦型桩的沉降量显著增加,表面劣化引起的附加沉降可能影响桩的正常使用.

A series of model tests on friction piles in corrosive foundation model were conducted to investigate the settlement characteristics of friction piles （ end-bearing friction pile and friction pile） under working load in corrosive foundation. The copper sulfate solution as the corrosive medium was adopted to make the foundation model, which could accelerate surface deterioration speed. Then the settlement law of friction piles with surface deterioration under working load was investigated. The results indicated that the deterioration degree around pile surface increases with time, and the settlements increase with the deterioration degree. The load-settlement curves of end-bearing friction pile and friction pile were different. After 17 360 minutes under working load, the percentage of settlement on end- bearing friction pile reaches 28.5% of pile diameter. The settlement caused by skin deterioration is 10.6% which is larger than the settlement of friction pile with 7%. By the end of the test, the settlements of two types of piles reach the settlements corresponding to the ultimate bearing capacities respectively. Surface deterioration can cause significant incensement of friction pile settlement. This may affect the pile normal function.