临海粉煤灰吹填区旋喷桩止水帷幕施工技术研究

沿海地区存在较多的填海造陆区域,其中不少区域利用粉煤灰回填。粉煤灰颗粒小,渗透性强,易扬尘,充填区临海,地下水水位高,补给速度快,基坑开挖时易渗水和管涌,综合考虑地质情况和经济效益,该工程决定采用高压旋喷桩止水帷幕止水。研究了三管旋喷施工工艺,着重研究如何控制冒浆量和施工中遇到浆液流量、压力等情况异常时的应对措施,以及现场安全用电、控制扬尘等安全环保问题,施工完毕28d后桩体强度检测达标,基坑开挖过程中未出现明显渗漏,说明止水帷幕效果良好。

CONSTRUCTION TECHNOLOGY OF HIGH-PRESSURE JET GROUTING PILES WATER-STOP CURTAIN AT COASTAL FLY ASH DREDGER FILL AREA

In some sea reclamation areas,fly ash acts as backfilling materials.Fly ash particle is tiny with a high permeability and ease of raising dust,while the underground water level is high and recovery of water-level is quick at coastal fly ash dredger fill area,result in water leakage and piping effect in process of excavation of foundation pit.Based on geological condition and economic efficiency of the project,it was decided to adopt high-pressure rotary-jet piles as water-stop curtain.Construction technology of three-pipe jet grouting was studied,including control of the cement grout return speed,solutions to deal with anomaly of cement grout flow rate and pressure,and security and environmental protection problems such as electricity safety and dust control.Water-stop curtain was proved to work well that pile-intensity was up to the 28 d standard and there was no apparent leakage during excavation of foundation pit.