湛江深厚老黏土地区钢管桩沉桩规律

Regularity of pile-sinking construction for steel tube piles in Zhanjiang deep old deposited soil

对湛江老黏土地基5个工程钢管桩施工进行总结，得出以下结论：老黏土地区持力层宜选择50击的中粗砂层或者40击以上黏土层，此时基桩承载力恢复系数为1．26-1．40，比一般黏性土高；打桩锤宜选择D128、D138柴油锤，二档档位终锤贯入度宜为2—5mm／击，三档档位终锤贯入度为6～10mm／击，能量传递系数为28．5％～47．6％；当持力层和桩锤符合上述情况时，直径在1000～1400mm的钢管桩总锤击数小于2500的占统计83．8％，打桩效率最高。

Based on summarizing sinking construction for steel tube piles in 5 projects, conclusions are as follows. The bearing stratum of steel tube pile in deep deep old deposited soil of old deposited soil should be medium coarse sand of 50-blow count SPT or deep old deposited soil of 40-blow count SPT. The coefficient of restitution for pile capacity is 1.26 - 1.40 and higher than other caly soil. Diesel hammer of D128 or D138 should be chosen for pile driving equipment. The final set should be 2 - 5 mm/blow for second gear and 6 ~ 10 mm/blow for third gear. Energy transfer coefficient for steel tube piles in deep old deposited soil is 28.5% ~ 47.6%. The total number of blows less than 2 500 is 83.8% of the statistics steel tube piles with diameter 1 000 - 1 400 mm and pile driving efficiency is highest when the bearing stratum and final set is as above-mentioned. Furthermore, the control standard of pile-sinking construction soil can give instruction to theoretical research and engineering practice for steel tube pile in deep old deposited.