基坑弱渗透性土层界面滞水导排技术研究  

Water Retention and Drainage Technology at Weakly Permeable Soil Layers Interface in Foundation Pits

作　　者：石佳丽 雷开亮 亢佳伟 SHI Jiali;LEI Kailiang;KANG Jiawei(China Railway Third Bureau Group Bridge and Tunnel Engineering Co.,Ltd.,Chengdu,Sichuan 610048,China;Xi′an Loess Underground Project Technology Consulting Co.,Ltd.,Xi′an,Shaanxi 710054,China;Institute of Geotechnical Engineering,Xi′an University of Technology,Xi′an,Shaanxi 710048,China)

机构地区：[1]中铁三局集团桥隧工程有限公司,四川成都610048 [2]西安黄土地下工程技术咨询有限公司,陕西西安710054 [3]西安理工大学岩土工程研究所,陕西西安710048

出　　处：《水利与建筑工程学报》2024年第3期58-65,142,共9页Journal of Water Resources and Architectural Engineering

基　　金：国家自然科学基金项目(52178355)。

摘　　要：在渗透性差异较大的土层互层剖面中,“界面滞水”是工程降水过程中施工风险高、处置难度大的一大技术问题。为确保基坑开挖安全及地下结构施作质量,改善土体强度、降低工程施工风险,提出一种降水井、集水井和砂井相结合的层间滞水导排技术,依托某区域基坑降水工程,在现场观测的基础上,分析砂井尺寸、布井间距和设置深度对基坑侧壁滞水导排效果的影响,并验证该滞水导排技术的可行性和合理性。研究结果表明:砂井的设置,可以为低渗透性土层处的界面滞水提供顺畅的竖向渗流通道,能实现预先主动的地下水控制,对保证地下结构施作质量、土层疏干效果和提高土体强度具有有益效果。砂井的导排水影响范围主要由低渗透性土层的水平向渗透特征所决定,随着砂井直径增加,其滞水导排范围约为6 m~8 m,布井间距建议为10 m~15 m;砂井的设置深度应穿透水位降深范围内低渗透性土层,且不应超过实际降水位以下,规避因砂井的设置导致水分积聚造成工程风险。In the interlayer profiles of soil layers with significant differences in permeability,"interface water retention"is a major technical problem with high construction risks and is also very difficult to disposal during the engineering dewatering process.In order to ensure the quality of underground structure construction,improve soil strength,and reduce construction risks,an interlayer stagnant water drainage technology combining precipitation wells,collection wells,and gravel wells is proposed.Based on the on-site observation of a foundation pit dewatering project in the Loess Plateau area,the influence of gravel well size,well spacing,and setting depth on the stagnant water drainage effect of the sidewall of the foundation pit is calculated and analyzed,and the feasibility and rationality of this stagnant water drainage technology is preliminarily verified.Results are as follows.The setting of gravel wells can provide a smooth vertical seepage channel for stagnant water at the interface of low permeability soil layers,achieve proactive groundwater control in advance,and have beneficial effects on ensuring the quality of underground structure construction,soil layer drainage effect,and improving soil strength.The range of influence of gravel well drainage is mainly determined by the horizontal permeability characteristics of the low permeability soil layer.As the diameter of the gravel well increases,its stagnant water drainage range is 6 m~8 m,and it is recommended to arrange wells with a spacing of 10 m~15 m.The depth of the gravel well setting should penetrate the low permeability soil layer within the range of water level drop,and should not exceed the actual precipitation level to avoid the risk of water accumulation caused by the gravel well setting during the project implementation.

关 键 词：工程降水 界面滞水 砂井 布井间距 

分 类 号：TU463[建筑科学—结构工程]