对某高原铁路桥隧相连工程穿越不稳定斜坡体进行研究,分析了斜坡体失稳的原因,基于传递系数法分别计算其天然工况下和地震工况下的坡体稳定系数以判定坡体的稳定性,并求得坡体推力.结合计算结果,对该斜坡体采取抗滑桩、桩间土钉墙和桩顶锚索等综合整治措施,有效提高了斜坡体的稳定性,保证了工程安全可靠,为工程设计和施工提供了经验.

为解决矿山法铁路隧道施工拱部常出现的衬砌背后脱空、二次衬砌厚度及强度不足等质量缺陷问题,提出矿山法隧道拱部采用装配式预制管片结构的新思路,并基于时速350 km双线铁路隧道,采用数值计算分析研究拱部装配式衬砌结构的系列设计参数.主要研究结论有:1)提出拱部装配式衬砌环向不分块的整体预制形式,综合考虑理论计算结果、行车安全分析、机械设备运输及拼装能力、拱部衬砌承载能力等,确定拱部管片环向弦长8.6 m、纵向幅宽2 m、衬砌厚度50 cm的结构尺寸及配筋设计参数;2)提出拱部预制管片之间环缝采用螺栓连接、拱部预制管片与现浇边墙采用"L"型榫接头的接头形式及其设计参数;3)为保证拱部管片的顺利安装,"L"型榫接头应考虑一定的施工误差,同时拱部预制管片与初期支护间应预留安装空间,后期通过管片背后纵向注浆填充密实.隧道拱部装配式衬砌技术成功应用于重庆胡家沟隧道,总体实施效果较好.

为降低隧道内渗漏水风险、保障运营期间隧道安全,依托上元门越江隧道工程防水设计方案,利用ABAQUS有限元软件建立了密封垫-管片沟槽三维精细化模型,研究了高水压盾构隧道管片T型缝处不同张开量下不同截面形式密封垫的防水特性.结果表明:T型缝处两个L型密封垫角部刚度较大,管片压缩后密封垫与角部接触部分变形较大;环缝和纵缝交点附近的平均接触应力最大,随着与交点的距离逐渐增大,接缝上平均接触应力急剧减小,在距交点10～25 mm范围内存在有应力谷;纵缝上靠近密封垫角部的应力谷位置是T型缝处最容易发生渗漏水的部位;同一张开量下,圆形开孔密封垫防水能力优于三角形开孔密封垫与无开放孔密封垫,建议在高水压盾构隧道管片T型缝处选用圆形开孔密封垫.

近年来,黔桂、广昆、沪昆等铁路隧道运营期间发生了若干起边墙开裂、仰拱隆起、无砟道床变形等水害事件,直接影响着衬砌、轨道等结构的正常使用功能及耐久性能,严重的病害则直接威胁着铁路隧道特别是高速铁路隧道的正常运营安全.为有效降低复杂岩溶地区隧道工程的水害风险,通过调研目前铁路隧道主要水害类型,分析现行衬砌排水系统存在的问题,提出一种适用于岩溶隧道的新型衬砌结构,通过建立有限元模型,对衬砌结构受力进行对比分析.主要结论如下:(1)研究提出的"疏水型箱式隧底衬砌",具有"隧底开挖施工方便、不良地质适宜性强、排泄路径直接、隧底泄水快、排水断面自由度高、泄水能力强"等特点,能充分满足复杂岩溶隧道受力及排水的需求;(2)同现行仰拱型衬砌结构相比,在不增加结构厚度及配筋的基础上,疏水型箱式隧底衬砌结构受力更为均衡.

渝昆高铁长度大于20 km的特长隧道有两座,且两座隧道相距较近,文章对该两座隧道采用合修及分修方案分别进行了研究,对影响范围的站前、站后工程,从工程规模、工程建设、运营安全、工程投资等方面进行了系统研究比较,为渝昆高铁勘察设计阶段线路方案的确定提供了有利的支撑,对其他铁路项目建设具有较高的指导性意义.

本文针对贵南高速铁路隧道工程岩溶发育、分布广、段落长、建设风险高的特点,在总结传统岩溶隧道防排水问题基础上,研究提出了一种适用于复杂岩溶地区的底板型箱体排水新型衬砌结构,可有效降低复杂岩溶地区隧道工程的水害风险.

成贵高铁玉京山隧道穿越巨型溶洞,溶洞顶板处有大直径不稳定楔形体,为防止施工过程中隧道顶部出现掉块和坍塌,提出采用涨壳式中空注浆锚杆与低预应力全黏结型锚索联合加固溶洞顶板的治理措施.采用有限元软件分别建立顶板无支护、仅设置锚杆支护及锚杆和锚索联合支护3种工况下围岩的三维数值模型,同时考虑支护滞后时顶板围岩的加固效果,通过数值模拟结果对比分析不同工况下锚杆、锚索轴力的变化规律及围岩位移、塑性区的分布规律,并提出一种有效的顶板防护措施.结果表明:1)锚杆和锚索及时支护可以有效控制顶板不稳定围岩的位移、塑性区发展,达到较好的加固效果;2)在仅设置锚杆的基础上及时施加锚索结构可以显著降低锚杆的轴力,避免锚杆因轴力太大而破坏;3)采用涨壳式中空注浆锚杆与低预应力全黏结型锚索结构对玉京山隧道溶洞顶板进行加固可以保障隧道施工安全.

成兰铁路桥隧比重大,高达90％以上,且大多桥隧相连,加之沿线地震效应明显,洞口坡面危岩落石发育.为确保运营安全,选择合理的桥隧防护结构至关重要.文章结合成兰铁路地质地形特点及桥隧结构布置,提出了几种典型的桥隧共同防护结构,并开展了室内试验.根据试验结论,依托茂县隧道出口,建立了高陡边坡桥隧相连洞口危岩落石综合防护系统及桥隧共同防护结构,可为复杂艰险山区铁路桥隧共同防护设计提供参考.

针对大跨大断面隧道,若按传统设计,锚杆长度及环、纵向间距等参数沿拱墙范围不变,势必产生浪费,增加成本.为了解特大跨大断面浅埋隧道分部开挖施工过程中锚杆的受力变化特征及各部位最终受力状态,以六(盘水)沾(益)铁路乌蒙山2号4线车站隧道工程为背景,采用数值模拟和现场测试方法,开展分部开挖系统锚杆轴力分布特点研究.研究结果表明:1)锚杆受力大小与部位相关,不同部位的锚杆轴力差异显著,边墙部位锚杆轴力>拱肩部位锚杆轴力>拱顶部位锚杆轴力.2)基于锚杆受力特征可知,系统锚杆可采用不等参支护.3)大跨大断面隧道采用系统锚杆不等参支护,既经济又可节省工程建设时间.

在我国西部地区存在着大量地形切割强烈,重力型不良地质发育的艰险困难山区,地形条件复杂.与普通隧道段相比,洞口段坡度极大,往往存在着大量不稳定岩体,进洞十分困难,稍有不慎,极易引发次生灾害.文章结合西部艰险山区洞口特点,针对性地给出了穿越高仰边坡和岩堆、滑坡等不稳定体的典型进洞技术,供广大工程人员借鉴.

针对钻爆法施工隧道二次衬砌采用模筑混凝土衬砌时其施工速度慢且拱部衬砌质量难以达到设计要求等问题,提出适用于钻爆法施工的双线铁路隧道预制拼装二次衬砌结构分块方案.基于盾构法隧道管片接头的计算理论,计算得到预制二次衬砌横向和纵向接头的刚度值.利用梁-弹簧计算模型对不同分块方案进行对比和分析,研究不同厚度拼装衬砌的受力特性,提出较优的拼装二次衬砌厚度为500 mm.同时采用壳-弹簧计算模型对不同幅宽的通缝拼装二次衬砌内力分布进行了分析,结果表明,预制拼装二次衬砌内力分布具有明显三维特性,接头边缘部位弯矩较大,而中部弯矩较小,拼装二次衬砌的幅宽宜为2.0 m.

艰险山区铁路弃渣场建设具有弃渣规模大、可用渣场少、环境保护形势严峻、堆渣总高度大、坡度陡、失事危害程度高等特点.为确保弃渣场建设及运营安全,加强环境保护及水土保持,本文基于成兰铁路弃渣场建设工程实例,建立了艰险山区弃渣场的设计流程,提出了从弃渣场选址、稳定性分析、主体工程设计到绿色防护的系统设计方法,为艰险山区弃渣场设计、施工提供指导和参考,对减少弃渣场地质灾害、保护环境、实现水土保持、顺应环保新形势具有显著作用.

Compared with traditional single and double track railway tunnels,the span and the excavation area of the large-span four-track railway tunnel are much larger.In order to improve the utilization ratio of tunnel space and reduce project cost,the section of the tunnel becomes more flat,and the stress redistribution after tunnel excavation would be worse,which add more difficulties to structural design and construction.On the contrary,in view of the pure stress,the lining structure should be the inner contour of near round,which results in low space utilization rate,substantial increase of excavation and masonry,production waste and additional cost.With reference to the construction of No.2 Wumengshan large-span four-track railway-station tunnel,reasonable inner contour and the range of flat ratio are determined based on the analysis and comparison of the stress,displacement and plastic zone of surrounding rock,and the carrying capacity and economy of the lining structure to meet the operational requirements of construction clearance and related conditions.This research provides some references for determining inner clearance of Large-span tunnel lining.

The construction of ultra large-span four-track tunnel,of which the excavation area equals to 6 times of that of traditional single-track railway tunnel,is difficult;and there is no successful precedent.The construction methods for ultra large-span four-track deep tunnel on Wumengshan No.2 exit section on Liupanshui-Zhanyi Railway are studied by numerical simulation and site monitoring methods.The results show that:1) By using temporary support replaced by prestressed anchor,the temporary support of arch is successfully dismantled,the replacing construction risk of arch is reduced;the disadvantages of traditional soft rock tunnel construction are overcome;the safety and flexibility of support dismantling are improved;and large working face can be provided for followed construction step.2) By using temporary cross-brace replaced by prestressed anchor cable,the temporary cross-brace dismantling risk is avoided;and the construction flexibility is improved.3) The three-bench excavation of ultra large-span tunnel is realized by using temporary support replaced by prestressed anchor and temporary cross-brace replaced by prestressed anchor cable.

It is a key to determine the surrounding rock pressure in the design of the tunnel. The calculation formula of surrounding rock pressure of deep depth railway tunnel in China is an empirical formula established by statistical data based on the construction of a large number of tunnel collapse events. It plays a very important role in the structural design of single and double-track tunnels, but it could hardly possible to guide the design of the three-track, especially the four-track railway tunnels. Therefore,it is urgent to formulate a method to calculate the surrounding rock pressure of multi-track tunnel. The theory of"unified pressure curve of surrounding rock"is proposed. Based on the construction of No. 2 Wumengshan large-span four-track railway-station tunnel, field experiments are carried out to test surrounding rock pressure. Combined with the theory of"unified pressure curve of surrounding rock", this paper puts forward the calculation formula of q=Kyhafor vertical surrounding rock pressure.

当前针对地下结构的抗震设计分析方法有很多,但各种方法均存在一定的局限性,如目前铁路隧道抗震采用地震系数法也并不能准确反应隧道的地震力响应规律。反应位移法作为日本等国家采用的抗震设计方法在地震力分析时具有一定的优越性,通过其与当前设计方法的计算对比,可以为我国铁路隧道抗震设计提供借鉴。

本文以乌蒙山二号四线铁路隧道为工程依托,采用数值模拟和现场测试手段,开展多部开挖系统锚杆功效及轴力分布特点研究。研究结果表明:基于依托工程施工工法和计算条件,系统锚杆轴力呈现"拱肩（①②部）＞拱脚（④⑤部）＞边墙（⑥⑦部）＞拱顶（③部）"的分布;拱顶锚杆轴力甚小,基本未起作用;拱肩部位锚杆轴力最大,作用明显。通过跟踪相应路径的围岩变形深表比,可以得出锚杆受力与锚杆施作后实际捕获的围岩相对变形（深表比）密切相关,从某种意义上来说,锚杆轴力大小表现为"施作部位（空间）"和"施作先后（时间）"的乘积关系,施作部位决定可能的相对变形,施作时间决定实际捕获的有效相对变形,只有当两因素同时起正面作用时,锚杆轴力才会显大。现场实测锚杆轴力分布特点与数值模拟结果较为吻合,实测最大值为58.1kN。

By means of theoretical analysis and numerical simulation,the influence of the span length on the surrounding rock stability was researched. The results indicate that if only the elastic secondary stresses occurred after the excavation,the influence on the surrounding rock stress state would be little by merely increasing the tunnel span length without changing the section shape. But if the plastic zone occurred after the excavation,and even if the section shape were not changed,the radius of the plastic zone would be increased by merely increasing the excavation span length, and consequently the surrounding rock stability would be weakened. Moreover,based on the example of Wumengshan No.2 railway four-track tunnel,the comparative analysis of the failure modes of unlined tunnels was conducted between the deeply-buried case and the shallow-buried case. The result suggests that for the shallowly-buried case,the support system should be dominated by the rigidity requirements,so as to reduce the release and control the settlement; while for the deeply-buried case,the support system should be dominated by the strength requirement,with the appropriate releasing and controllable deformation.

The construction of underground tunnel plays a more and more important role on the development of big cities. One of the most important problems caused by the construction of tunnel is that underground excavation will cause large settlements of ground buildings. And it heavily affects the safety of the building. The depth of underground tunnel and the horizontal distance between the tunnel and the building are two important factors which have great influence on the settlements of ground buildings. During the designing of tunnels these two factors must be taken into account. It is necessary to find out the regulations between the settlements of buildings and those two factors. On the other hand, the loess plateau in the west of China has a vast territory, integrated strata and large depth, which is rare in the world. Currently in big cities located in the loess areas, such as Xi'an, underground tunnel is preferred to be adopted to solve the traffic problem. So it is of great importance for the construction of underground project to research the relationship between the building subsidence and the excavation of underground cavity or the construction of underground tunnel in western China. This paper will aim to find out the quantity rules that how the underground tunnels affect the settlements of ground buildings in the loess areas. According to the mechanical characteristic of loess, the Duncan-Chang non-linear elastic constitutive model will be adopted; through the simulation in term of the FEA program- GeoFBA, the regulation that how the depth of underground tunnel and the horizontal distance between the tunnel and the buildings influence the settlements of ground buildings, will be obtained. And this result can be used as theoretic reference to the construction of the underground engineering in loess areas. (A) This paper was presented at Safety in the underground space - Proceedings of the ITA-AITES 2006 World Tunnel Congress and the 32nd ITA General Assembly, Seoul, Korea, 22-27 April 2006. For the covering abstract see ITRD E129148. Reprinted with permission from Elsevier.

According to the mechanical characteristics of loess soils, the Duncan-Chang non-linear elastic constitutive model was adopted. Considering the effect of excavation of shield tunneling on adjacent buildings, a finite element model on the interactions between soil and lining was established. The law of the influence of shield tunneling on settlement of ground surface in loess strata was discussed, and the results indicate that the settlement of ground surface reduces near-linearly with the increasing depth of tunnel in the same outer diameter of shield tunneling; the settlement of ground surface increases near-linearly with the increasing outer diameter of shield tunneling in the same depth of tunnel; and no matter what size the outer diameter of shield tunneling is, the settlements of ground surface above the tunnel and the adjacent buildings reduce with the increasing ratio of the horizontal distance between the shield tunneling and the building to the outer diameter of shield tunneling, and also reduce when the depth of tunnel increases. This research offers a theoretical reference to the construction of metro engineering in west China.