泥质岩地区大直径深嵌岩桩的承载特性

Bearing Characteristics of Large Diameter and Deep Rock-socketed Pile in Argillaceous Area of Guizhou Province

基于自平衡桩基测试技术,根据坝陵河大桥现场的2根桩基(SZ1、SZ2)和北盘江大桥的1根桩基(SZ3)的静载荷试验报告,对泥质岩地区大直径深嵌岩桩(嵌岩比hr/d>3.0)在万吨级荷载作用下的承载特性进行了研究,包括桩顶荷载和位移的关系、桩侧阻力、桩端阻力等。结果表明:在泥岩地区大直径深嵌岩桩桩顶荷载-位移曲线主要以缓变型为主;桩端岩石风化程度对端阻力影响较大,微风化的泥质砂岩和白云岩极限承载力要比弱风化的泥质灰岩高;桩侧阻力的发挥与桩土界面相对位移关系比较密切,泥质白云岩桩侧阻力发挥所需桩土位移相对位移较小;最后把桩极限侧阻力与勘探报告预估值进行了分析。

Based on the advanced technique of self-balancing test,the bearing characteristics of large-diameter deep rock-socketed pile（hr/d3.0）,including the relation of load and displacement on top of it,side friction,the tip resistance and so on,under 10 thousand-ton load level in argillaceous area had been analyzed according to the report of static loading test on 2-piles of Balinghe River Bridge and 1-pile of Beipan River Bridge.The results indicate that Q-s curve of large diameter pile in mudstone declines slowly,and the weathering level of rock has great impact on tip resistance of pile.The ultimate bearing capacities of sandstone and dolomite in puny weathering are stronger than that of limestone in weak weathering;the side friction of pile is closely related to relative displacement of pile-soil interface,and the side resistance of pile in argillaceous dolomite needs smaller pile-soil relative displacement.Finally,the ultimate values of lateral resistance of pile and estimate of exploration report have been comparative analyzed.