研究目的:通过介绍近年来对地铁车站围护结构组合的应用研究与实际应用经验，探讨和创新设计理 念，以期达到安全经济的目的。
研究方法:通过工程实践，结合工程周边环境、地质水文情况，对地铁车站围护结构形式和施工技术进行 深人的阐述，并将单一的围护桩支护形式和土钉墙与围护桩组合形式进行了对比分析。
研究结果:在基坑开挖过程及车站主体施工阶段，基坑围护经历了时间和恶劣天气的考验。通过对基坑 的监控量测，基坑位移及地面沉降等各项数据都在控制值范围之内，充分验证了基坑的安全性。
研究结论:在地质及周边环境允许的情况下，基坑围护采用上部放坡土钉支护、下部排桩+内支撑或预应 力锚索支护方案，有利于土方挖运，提高了机械利用率，施工进度快，且节约了成本;设计时应根据地质勘察报 告，分析场地土的性质，根据理论分析、类似工程的经验和监控量测结果，及时修正设计参数。
Research purposes: Based on the introductions to the applicable research and experiences of exterior- protected construction for Metro stations，the exploration and innovation of design concept are made for the purposes of security and reduction of cost.
Research methods: Based on the construction practice and the surrounding environmental and hydrological conditions of construction, the deep explanations are given to the forms of exterior-protected construction for Metro station and its construction technology, and the analyses are made for the comparison of support form of fender post alone and soil-nailed wall with the combined forms of fender post.
Research results : In the phases of excavation of foundation pit and construction of the main body of station , the fender for the foundation experienced the tests of time and bad weather. Through making measurements to the foundation pit, the displacement of foundation pit and surface subsidence were in the range of control values，which showed foundation pit is in the safety.
Research conclusions: If the geologic and surrounding environmental conditions allow, what can be done for supporting foundation pit is that the top of foundation pit is supported by soil-nail and the bottom is supported by raw piles plus interior support or stressed anchors, so it is helpful for excavation and movement of earth, enhancing utilization of machinery, speeding up the construction process and saving cost. In the course of design, the design parameters should be modified on time in accordance with the geological survey report，soil characteristics, theoretical analysis results , experience of similar construction and measurement results.
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