东非某工程嵌岩灌注桩钢护筒卷边问题分析

On steel casting crimping of rock-socketed cast-in-place pile in East Africa

东非某水工码头桩基础为嵌岩灌注桩,桩尖进入强风化岩层,嵌岩至钢护筒底部以下8 m。在引桥钻进过程中,钢护筒出现卷边现象。高应变全程动测结果显示,持力层较硬,能量传递效率达到92.4%,桩身最大应力为220 MPa。经设计指示,最后10击的平均贯入度减少,钻岩深度增加至13 m,修改沉桩方案后持力层由强风化变成全风化层,卷边现象基本上消除。本工程经验可为嵌岩灌注桩理论研究和工程应用做出参考。

The rock-socketed cast-in-place pile is used in a hydraulic dock in East Africa. The bearing stratum is strongly weathered rock and the socketed depth is 8 m under the pile tip of steel casting. The crimping of steel casting is found during drilling. Whole-process PDA test shows that the bearing stratum is hard, the transfer efficiency of energy is 92. 4%, and the maximum stress of the steel casting pile is 220 MPa. The average set of last 10 blows is decreased as the designer requires and socketed depth increases to 13 m. The bearing stratum is completely weathered rock according to the new scheme and crimping completely disappeares. The engineering experience may serve as reference for the theoretical research and engineering practice of rock-socketed cast-in-place piling.