马家山隧道出口边坡预应力锚索施工技术

Construction Techniques of Pre-Stressed Anchor Cables for the Exit Slope of the Majiashan Tunnel

马家山隧道出口端处于基岩风化层中，隧道洞口下方为县级公路，由于修筑公路形成高25．30m、坡度70°的人工边坡，山坡陡峭；为稳定岩体，边坡防护主要采用“SNS主动防护网＋预应力锚索”对洞口地表进行加固。文章介绍了预应力锚索施工技术在马家山隧道洞口边坡防护工程中的应用，包括预应力锚索的设计、施工、机械设备及其质量和安全保证措施。工程实践表明：预应力锚索具有土石方及混凝土工程量小、总体造价低、隐埋于土中、美化环境等优点；锚索施工过程中对边坡及周边环境影响小，能够保证施工安全、达到加固工程的预期目的。

The exit section of the Majiashan tunnel is located in a weathered bedrock layer, with a county-level road underneath. Due to the construction of the road, an artificial steep slope of 70~ and 25 ~30m high was formed. To stabilize the rock mass and strengthen the ground, SNS active protection mesh and a pre-stressed anchor cable were adopted. In this paper the application of the pre-stressed anchor cable construction techniques to the portal slope reinforcement of the Majiashan tunnel are introduced, including the design, construction, equipment, quality control and safety measures, etc. The engineering practice indicates the slope reinforcement with a pre-stressed anchor cable has the advantages of small quantities of earth-work and concrete, as well as low costs and minimal landscaping. Additionally the construction of the anchor cable has less impact on the slope and the surrounding environment, assuring safe construction and obtaining reinforcement goals.