为解决土压平衡盾构在敏感软土地层穿越密集房屋群过程中极易引发地表沉降和建（构）筑物损坏的问题，依托广州市轨道交通14号线盾构下穿姓钟围房屋群加固工程，提出水平定向注浆加固技术,该技术将水平定向钻孔技术与地面注浆技术相结合，利用无线随钻测斜系统实现钻机参数测量、采集、分析和定位，采用特制钢阀管下入钻孔，通过阀管向拟加固区域进行水平定向注浆。介绍该技术的水平孔钻探工艺，并分析其应用效果和经济效益。结果表明： 应用水平定向注浆加固技术，加固区变形量控制在±5 mm以内，未造成房屋开裂、倾斜、倒塌等不良社会影响，能有效保障土压平衡盾构在敏感软土地层中安全顺利通过密集房屋群； 水平定向注浆加固较MJS高压旋喷桩加固可节省费用600余万元，经济效益显著。

The ground surface settlement and building damage are easily occurred during earth pressure balance shield crossing underneath concentrated building group in sensitive soft soil stratum. Hence, the horizontal directed grouting reinforcement technology is proposed based on shield crossing underneath Xingzhongwei building group reinforcement project of Guangzhou Metro Line No.14. The technology combines horizontal directed drilling technology with ground surface grouting technology, uses the wireless MWD system to measure, collect, analyze and locate, and grouts through speciallymade steel valve pipe. The drilling technology of horizontal holes is introduced； and the applicable effect and economic benefit of the technology are analyzed. The study results show that: (1) By using the horizontal directed grouting reinforcement technology, the deformation of reinforced zone is controlled within ± 5 mm； no building cracking, tilting and collapsing happen; and the shield crosses underneath concentrated building group in soft soil stratum safely and smoothly. (2)The cost is saved by more than RMB 6 million compared with MJS high pressure jet grouting pile reinforcement scheme, which shows remarkable economic benefit.