大粒径卵砾石地层多管同步注浆止水技术与试验研究
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摘要
大粒径卵砾石地层影响半径大、渗透系数高、地下水补给量大,若采用降水方法进行地下水控制,将导致严重的水资源浪费;而该类地层可适用的帷幕止水方法种类较少,且不同止水方案对工期、造价影响较大。以北京地区某深基坑工程实例为分析条件,提出了多管同步注浆止水帷幕方案,通过开展工程场区内的现场注浆模型试验,系统研究了多管同步注浆的施工工艺、注浆材料及施工参数等关键技术指标。通过现场测定及室内分析,大粒径卵砾石地层袖阀管同步注浆扩散半径大于0. 5 m,注浆固结体渗透系数约5, 2×10~(-6) cm/s,可有效降低卵砾石地层的渗透性、极大程度减少基坑抽排水量,是一种可靠的深基坑工程止水辅助施工技术,可为类似地层条件下深基坑工程地下水控制设计及施工提供参考。
The large influence radius and the high permeability coefficient are the characteristics of large particle gravel strata which holds abundant groundwater. Using the method of precipitation to control the groundwater will cause serious waste of water resources. The sealing curtain techniques are fewly applicable to the large particle gravel strata. In addition, different water-blocking schemes have great influence on the construction period and cost. By taking an example of deep foundation pit in Beijing as the analysis condition,this paper puts forward a scheme with multi-pipe synchronous grouting and water-blocking for deep foundation pits. By carrying out grouting model tests in the engineering site, some key technical indexes, such as the construction technology, grouting material and construction parameters, are systematically studied of multi-pipe synchronous grouting. By field measurement and laboratory analysis, this paper makes the following conclusions: When the grouting diffusion radius is greater than 0. 5 m and the permeability coefficient of grout is greater than 5, 2 ×10~(-6) cm/s, by using the method of synchronous sleeve valve tube grouting in large particle gravel strata, the permeability of gravel stratum will be decreased; The drainage of the foundation pit will be greatly reduced simultaneously.So this reliable water-blocking technique can provide reference for the groundwater control design and construction of similar foundation pit engineering in deep foundation pit.
The large influence radius and the high permeability coefficient are the characteristics of large particle gravel strata which holds abundant groundwater. Using the method of precipitation to control the groundwater will cause serious waste of water resources. The sealing curtain techniques are fewly applicable to the large particle gravel strata. In addition, different water-blocking schemes have great influence on the construction period and cost. By taking an example of deep foundation pit in Beijing as the analysis condition,this paper puts forward a scheme with multi-pipe synchronous grouting and water-blocking for deep foundation pits. By carrying out grouting model tests in the engineering site, some key technical indexes, such as the construction technology, grouting material and construction parameters, are systematically studied of multi-pipe synchronous grouting. By field measurement and laboratory analysis, this paper makes the following conclusions: When the grouting diffusion radius is greater than 0. 5 m and the permeability coefficient of grout is greater than 5, 2 ×10~(-6) cm/s, by using the method of synchronous sleeve valve tube grouting in large particle gravel strata, the permeability of gravel stratum will be decreased; The drainage of the foundation pit will be greatly reduced simultaneously.So this reliable water-blocking technique can provide reference for the groundwater control design and construction of similar foundation pit engineering in deep foundation pit.
引文
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[2]刘丽,姜爽,田松伟,等.严苛变形条件下卵石层深基坑降水及支护技术[J].工程勘察,2017,45(8):17-22.
[3]郑刚,朱合华,刘新荣,等.基坑工程与地下工程安全及环境影响控制[J].土木工程学报,2016,49(6):1-24.
[4]于海申,杨晨,肖大伟,等.天津周大福金融中心超深基坑地下水综合控制技术[J].施工技术,2017,46(23):98-102.
[5]吴奇,李俊才.高承压水基坑降水对周边环境的影响分析[J].南京工程学院学报(自然科学版),2015,13(1):6-11.
[6]薛丽影,杨斌,刘丰敏,等.基坑工程地下水渗流模型试验系统研究[J].岩土工程学报,2017,39(S1):126-130.
[7]罗富荣,曹伍富,韩煊,等.北京地铁7号线土建施工技术及应用[M].北京:中国铁道出版社,2018.
[8]陆建生.悬挂式帷幕基坑地下水控制中的尺度效应[J].工程勘察,2015,43(1):51-58.
[9]梁东,张淋柄,张戈.深基坑地下连续墙内支撑水平间距优化[J].市政技术.2016.34(5):179-183.
[10]崔永高.悬挂式帷幕基坑底侧突涌的坑内水头抬升研究[J].工程地质学报,2017,25(3):699-705.