基于复合式后压浆技术的深厚软土地层灌注桩设计

Design of Bored Piles in Deep Soft Soil Strata Based on Composite Post-Grouting Technology

针对灵昆车辆段上盖工程原灌注设计桩长下部成桩效率低、经济性差等问题,采用钻孔灌注桩桩底复合式后压浆技术进行桩长优化设计,并对经济性进行对比分析。研究结果表明:与开式后压浆试桩相比,采用复合式后压浆工艺其试桩单桩承载力提高34%~77%;温州地区桩端持力层为卵石层,通过注浆压力控制注浆速度,采用间隙注浆工艺,并确定一定的注浆量可确保注浆效果;通过桩基优化设计,原设计直径800、1000 mm桩进入卵石层长度减少8 m和13 m,造价分别节约1.35%、12.85%,工期缩短33.33%、50%,经济效益及工期效益显著。

In view of the low efficiency and poor economy of the lower part of the original cast-in-place pile in the upper cover project of Lingkun depot,the composite post-grouting technology at the bottom of bored piles is used to optimize the design of pile length,and the economy is compared and analyzed.The results show that the bearing capacity of single pile with composite post-grouting technology is 34%~77%higher than that of open post grouting pileꎻthe bearing stratum of pile tip in Wenzhou area is pebble stratum.The grouting effect can be ensured by controlling the grouting speed through grouting pressure,adopting the method of gap grouting and determining a certain amount of groutingꎻthrough the foundation optimization design,the length of the original design diameter 800 mm and 1000 mm piles into the gravel layer is reduced by 8 m and 13 m,the pile cost is saved by 1.35%and 12.85%,respectively,and the construction period is saved by 33.33%and 50%,respectively.The economic benefit and construction period benefit are very significant.