应用在地下工程施工中的新技术（Ⅱ）

为有效保护地面上的生态环境，开发利用地下空间资源并营建新世纪的地下水城，在新的21世纪里将会建造更多的地下工程以满足人们生产生活的各种需要。文中介绍了地下工程施工中采用的逆作法、盾构法、新奥法、沉管隧道、顶管工程和大型沉井施工新技术，供同行们参考应用。     

广成山隧道挤压大变形围岩的施工技术探讨

介绍了宜万铁路广成山隧道软弱围岩挤压变形控制施工技术,由于采取了有效的支护技术、开挖顺序、和相应的监测手段,保证了洞室的稳定,避免了隧道因挤压发生的变形侵限及塌方,为同类地质条件下的隧道工程施工提供了可借鉴的先例。     

黄土区湿软土层成洞技术研究

黄土区湿软土层成洞技术一直是水利水电工程及公路交通工程关键难题之一,主要介绍了湿软黄土层成洞技术的几种方法,着重介绍了目前广泛采用的新奥法施工原理,大管棚超前注浆支护的作用和原理以及施工工艺,为今后类似工程施工提供参考,对黄土高原淤地坝、土坝除险加固工程建设有着重要意义。实践表明:超前小导管与大管棚有机结合是黄土区湿软土层成洞的简单经济实用的施工技术。     

中国白银山隧道施工技术

白银山隧道全长390m,采用新奥法原理施工。利用光面爆破技术,Ⅲ类围岩全断面一次开挖,Ⅱ类围岩和断层破碎带半断面正台阶开挖。初期支护为锚喷及钢筋混凝土护拱,二次衬砌为模筑混凝土、洞内防排水采用复合式衬砌中间设聚氯乙烯薄膜结合纵向、环向育管及橡胶止水带的综合治理方案。对于特殊地质中的浅理、特浅理进洞的施工,坚持“护拱稳定边仰坡,大管棚注浆加固土体,浅打眼、弱爆破、强支护”的原则,做到安全进洞;对于断层破碎带,则采取了管棚注浆,超前锚杆预先加固围岩并结合钢格栅支撑等有力措施,顺利通过了不良地段。最后分析了浅理段荷载的计算,阐述了新奥法的岩体动态性质的力学概念。     

监控量测技术在隧道工程中的应用

本文以尚在建设中的宁夏同沿高速公路固原段三十里铺隧道为例，通过对隧道起安全监测作用的周边水平收敛、拱顶下沉、及洞口地表沉降等进行监控量测、数据采集、回归分析，初步研究了隧道围岩随时间变形的规律，提出监测工作应当是动态监测，只有作到及时检测，及时处理数据，及时反馈信息，用以指导施工，改进设计，才能充分发挥新奥法在施工中的作用。     

新奥法在百色水利枢纽导流洞设计和施工中的应用

新奥法是新奥地利隧洞施工方法的简称,也是近几十年地下工程设计和施工的新理论和新技术,它从根本上破除了岩石的散粒理论,充分考虑了围岩的自身承载能力。百色水利枢纽导流洞设计和施工中引进了这一先进理论和技术,而且创造性地把新奥法应用到软岩的地下工程,是对新奥法理论和技术的创新和发展。     

ADECO full-face tunnel excavation of two 260 m tubes in clays with sub-horizontal jet-grouting under minimal urban cover

With a cover of 5-30 m, a 260 m² cross-sectional area, and a 4-m wide pillar, the Cassia twin road tunnels underpass Cassia road (main road to/from Rome), the remnants of a 2000 year-old Roman villa, and two existing tunnels. Stiff silty clay dominates the alignment. According to the Analysis of Controlled DEformations (ADECO) principles, each tube was excavated full face to 260 m². Compared to Sequential Excavation Method (SEM), this highly simplifies construction, leads to construction industrialization, and allows for full control of the ground ahead of the face, which is used as a stabilization measure. In order to pre-confine the tunnel core, Trevi roto-injection technique was used to create an umbrella of overlapping sub-horizontal reinforced jet-grouting columns ahead of the face, while avoiding up heave of the ground or emptying of the columns. Stiff preliminary lining sitting on sub-horizontal jet-grouting columns, final invert close to the tunnel face, and final lining no more than 50 m behind the face ensured that the pre-confinement ahead of the tunnel face became effective confinement around the cavity. The tunnels were finished on schedule and within budget with a mere 1 cm of settlement.     

利民堡深埋红粘土隧洞的新奥法施工

粘土地层特别是在地下水位以下进行隧洞开挖时，随着洞周应力的释放将产生较大的收敛变形，极易导致围岩失稳并造成塌方，对于在埋深较大的塑性粘土地层中开挖隧洞，其施工难度就更大。作为一个典型工程实例，引黄南干５＾＃洞利民堡洞段粘土覆盖层厚度深达１８０ｍ，围岩应力高达３．６ＭＰａ，但由于合理运用了新奥法施工，包括采用分步开挖断面、适当预留收敛变形量、缩短开挖循环进尺、加密格栅拱架和及时喷混凝土支护等综合措施，因而顺利贯通。     

软弱破碎岩体中高压管道施工技术

龙首二级水电站高压管道在断层破碎带和影响带岩体中通过，岩质差、地质条件复杂，属IV～V类围岩。对此类岩体采用“新奥法”施工，即超前锚杆、超前导管，一次支护钢拱架、径向锚杆、挂网、喷护混凝土；二次永久衬砌和灌浆处理，在一次支护施工中进行了收敛变形量测。均获得了成功，保证了压力隧洞安全稳定和施工顺利完成。     

An application of three-dimensional analysis around a tunnel portal under construction

Deformation of a tunnel portal during tunnel excavation is very complex, and it can affect adjacent portal structures. During the construction of the Seoul Metro Line 7, a temporary vertical shaft was constructed by cut and cover method to take out a shield machine and to excavate subsequent tunnel by New Austrian Tunneling Method. Due to the complex structure of tunnel portals, the temporary support system of the vertical shaft was expected to be subjected to an additional load during the tunnel excavation. Thus, three-dimensional analysis of the vertical shaft, including tunnel excavation process, was performed in order to ensure the safety of overall system. This paper presents behavior of the vertical shaft based on the three-dimensional numerical analysis results during the construction sequence.