The study of seepage forces acting on the tunnel lining and tunnel face in shallow tunnels

In this paper, the seepage force problems arising from the flow of groundwater into a tunnel were studied. Firstly, the effect of seepage forces acting on the tunnel lining was studied for the case of shallow drainage-type tunnels and these results were compared with the lining stresses developed for waterproof-type tunnels. This model was then reviewed through a comparison with an actual case study of the Seoul Subway Line No. 5. Secondly, the effect of seepage forces on the tunnel face stability was studied. In this study, two factors were considered simultaneously. The first factor considered was the effective stresses acting on the tunnel face, calculated from the upper bound solution of limit analysis and the other factor was the seepage forces, calculated from a numerical analysis under a steady-state of groundwater flow conditions. Consequently, reasonable design concepts applicable to the design of tunnel lining and to the evaluation of the support pressure required for maintaining the stability of the tunnel face were suggested for underwater tunnels.     

成都地铁浅埋暗挖隧道衬砌混凝土施工技术

介绍了成都地铁浅埋暗挖隧道衬砌混凝土施工技术,重点阐述了衬砌模板支架方案和混凝土输送施工方案,指出了该施工方案能经济快速地完成混凝土施工,取得了较好的经济效益和社会效益。     

深圳地铁某区间隧道二衬结构数值模拟分析

以深圳地铁某区间隧道工程为例,运用大型有限元软件通过数值模拟的方式对隧道二衬结构进行了简单的力学分析,进而了解了地铁隧道复合式衬砌四心圆断面形式的基本受力特征,对类似隧道设计有一定指导作用。     

Evaluation of influence of vibrations generated by blasting construction on an existing tunnel in soft soils

The controlled blasting technique is employed, for the first time, on the diaphragm wall of an existing road tunnel in soft soils in the city of Shanghai, and therefore, safety demands on evaluation of influence of the blasting vibrations on the tunnel are highly required. Based on the practical blasting scheme of four sections of diaphragm wall of the tunnel to be exploded in three groups, the field monitoring of blasting vibrations is carried out on the bottom plate of the tunnel and the blasting vibration effects on the tunnel are measured throughout the blasting construction. The sequential characteristics of vibration velocities and accelerations of the tunnel structure are obtained from the field blasting tests. In order to fully understand the safety criterion of the blasting vibrations on the tunnel, a 3D numerical model is established by the finite element software ABAQUS. The numerical simulation results are confirmed by field monitoring data. Based on the monitoring data and numerical results of the tunnel subjected to blasting loads, results show: (1) the blasting energy is transferred mainly along the vertical direction; (2) the basic frequency domain of the tunnel responses caused by the explosion is relatively in a lower frequency range; (3) distinct vibration response spectra of the tunnel structure are observed along the horizontal and vertical directions; (4) the performance of the tunnel subjected to the blasting construction is in a critical state of safety and thus the blasting construction scheme should be implemented carefully. Finally, critical issues on evaluation of the blasting construction are fully discussed and evaluated, which provide a reference for other similar projects.     

An analytical method for internal forces in DOT shield-driven tunnel

This paper presents an analytical solution for the determination of internal forces of a jointed segmental precast DOT (Double-O-tube) lining. The unbalanced force transition method is combined with force method to establish an efficient analytical shortcut that simplifies tests and obtains the solution more effective than the existing methods to determine internal forces in the DOT tunnel lining. The in situ test on a DOT tunnel and a numerical simulation by FEM are conducted to verify the proposed analytical solution. The effects of shoulder ground pressure, soil resistance coefficient and open angle of DOT tunnel on the performance of tunnel lining are discussed as well.     

2D numerical investigation of segmental tunnel lining behavior

The application field of shield tunneling has extended in recent years. Most shield-driven tunnels are supported by segmental concrete linings. Although many well documented experimental, numerical and analytical results exist in literature concerning the functioning of segmental tunnel linings, their behavior under the influence of joints is still not clear.This paper presents a numerical study that has been performed to investigate the factors that affect segmental tunnel lining behavior. Analyses have been carried out using a two-dimensional finite difference element model. The longitudinal joint between segments in a ring has been simulated through double node connections, with six degrees of freedom, represented by six springs. The proposed model allows the effect of not only the rotational stiffness but also the radial stiffness and the axial stiffness of the longitudinal joints to be taken into consideration. The numerical results show a significant reduction in the bending moment induced in the tunnel lining as the joint number increases. The tunnel behavior in terms of the bending moment considering the effect of joint distribution, when the lateral earth pressure factor K₀ is equal to 0.5, 1.5 and 2, is almost similar and differs when K₀ is equal to unity. It has been seen that the influence of joint rotational stiffness, the reduction in joint rotation stiffness under the negative bending moment, the lateral earth pressure factor and Young’s modulus of ground surrounding the tunnel should not be neglected. On the other hand, the results have also shown an insignificant influence of the axial and radial stiffness of the joints on segmental tunnel lining behavior.     

城市地铁区间隧道监控技术与分析

结合深圳地铁3号线区间隧道施工实际,论述了地铁隧道结构位移、沉降的监控量测方案设计与实施方法,提出了具体合理的监测措施和预报流程,实践证明监测效果可靠,为保证该隧道的顺利贯通提供了可靠的技术保证。     

隧道二次衬砌混凝土快速施工技术

结合某隧道施工实例，阐述了混凝土快速施工方案，探索了采用机械化混凝土输送系统配合整体液压衬砌台车进行混凝土快速施工技术，并提出了系统的设计、选形与配套措施。     

整体式衬砌台车在公路隧道施工中的应用

对整体式台车的使用特点、工艺流程、质量控制方法进行了介绍,分析了其经济效益,经在公路隧道中推广应用,取得了良好的施工效果。     

衬砌施工缝防水技术在隧道施工中的应用

结合衬砌施工缝防水施工技术在胶新铁路下水峪隧道施工中的应用情况，分析了隧道渗漏水原因，介绍了预防措施，施工工艺要点，施工注意事项和劳动力组织，指出其施工效果良好，未出现渗漏水现象。     

南水北调中线渠道混凝土衬砌的施工质量控制

结合南水北调中线工程,从所处施工环境特点入手,分析了影响工程质量控制的关键因素,探讨了渠道衬砌混凝土质量的控制要点,指出应做好施工中各工序的质量控制,从而提高该工程的质量。     

Numerical simulation of the uplift behavior of shield tunnel during construction stage

In this study, a new 3D numerical model that considers the circumferential joint, longitudinal bolt, grout pressure, jacking force and the constraint of shield on the linings is developed to derive deeper insights into the lining uplift behavior during shield tunneling. The numerical analysis is conducted using ANSYS, which is verified by a case history in soft soils. Revealed by both the measurements and calculation results, it is found that the lining uplift due to shield tunneling in soft soils can be divided into three stages: dislocation, stretch and steady deformation stages, respectively. In the dislocation stage, the lining deformation attributes principally to the dislocation deformation between neighboring linings. In the stretch stage, the lining deformation is mainly caused by the stretch deformation of circumferential joints. The major uplift is caused during dislocation stage. Thereafter, the impacts of shield-driving parameters including gradient of grout pressure, jacking force and pre-tightening force of longitudinal bolts on the uplift behavior are investigated by a series of parametric studies. The jacking force during segment preparation and assembly shows the most significant impact on the uplift of the tunnel, while the pre-tightening force of longitudinal bolts shows negligible impact. Finally, the control criterion for lining uplift related to the allowable dislocation and opening angle of circumferential joints is proposed.     

防水板暗钉在高速公路隧道衬砌施工中的应用

着重介绍了太长高速公路官上隧道二次衬砌防水板暗钉的施工工艺、预防措施及其质量保障措施，指出施工中用暗钉铺设技术，有效保证了隧道衬砌无渗水，并保证了工程按期完成，为今后施工积累了经验。     

外水压下大断面公路隧道衬砌结构受力特性模型试验

矿山法修建的山岭隧道有的情况下对地下水采取排导式处理方案。当衬砌背后来水量超出排水系统能力时,将引起衬砌背后外水压增高,甚至导致隧道衬砌结构破坏。自行研制了隧道衬砌外水压力模拟加载试验装置,该装置通过形成负压环境,利用隧道结构模型内外气压差来实现外水压的模拟。基于隧道-地层复合模拟试验平台,开展了外水压下大断面公路隧道衬砌结构受力特性的室内加载模型试验。结果表明：衬砌结构在水土压力共同作用下,轴力呈锥形分布,拱脚轴力大于仰拱和拱部;弯矩呈蝴蝶型分布,拱脚处承受外弯矩,仰拱及拱顶承受内弯矩;轴力、弯矩随水压增加大致呈线性增大,偏心距逐渐减小,拱脚位置具有最大的偏心距,为外水压下隧道衬砌结构受力的最不利位置;依托隧道工程三车道及加宽带衬砌结构产生渗透性裂缝的外水压力分别为330kPa和420kPa,开裂裂缝主要出现在左右拱脚区域的外侧及仰拱内侧,为受拉开裂破坏,且随着外水压的增加,裂缝的渗透性急剧增大。此研究可为大断面公路隧道排水型衬砌在外水压力作用下结构安全评估提供参考。     

Design of shield tunnel lining taking fluctuations of river stage into account

Fluctuations of river stage are expected to induce changes in loads acting on the tunnel linings and cause readjustments of member forces in the segmental linings subsequently. Therefore, the evaluation of impacts of time-dependent river levels on the loads acting on the tunnel linings is of great importance in design of shield tunnel linings situated beneath the rivers. However, the loads acting the tunnel linings are generally considered as constant in most design methods available, taking no account of the influences of constantly changing river stage. In this study, the influences of river stage on design of shield tunnel linings are evaluated with respect to two common ground conditions: (a) impermeable overburden strata of low permeability and (b) permeable overburden strata of high permeability. Two earth pressure calculation models are correspondingly established. In addition, field observations in the Hangzhou Qiantang River Tunnel are described in detail to present the responses of tunnel linings to fluctuations in river stage and validate the established design model for the former case.     

隧道衬砌耐久性混凝土配合比设计及施工措施

从工程角度分析了混凝土耐久性失效问题及预防措施,探讨了耐久性混凝土的设计要点,提出了隧道衬砌耐久性混凝土的施工控制措施,以积累耐久性混凝土施工经验,推广耐久性混凝土的使用.     

软岩巷道网壳衬砌力学性能试验研究

针对地下工程新型支护方式——网壳支护,根据模型试验和理论,进行围压作用下相似模型试验,研究网壳衬砌力学性能和承载能力。通过试验结果分析,证明网壳支护结构具有良好的力学性能和较高的支撑能力,是一种可靠的支护形式,能弥补现有软岩巷道支护结构的不足。     

混凝土离析对隧道二次衬砌施工的影响

在隧道的二次衬砌施工过程中,由于混凝土的浇筑处于比较封闭、阴暗的环境中,对其浇筑过程的观察以及信息的反馈都不及时,容易导致混凝土浇筑过程中产生离析现象,形成混凝土结构不均匀,出现孔洞、水影和蜂窝状结构,在边墙下部也经常出现大片石子裸露的情况,直接影响隧道二次衬砌的强度和耐久性;同时,混凝土的离析,也直接影响泵送混凝土的输送。因此,研究混凝土产生离析的原因,可以提高施工效率和改善隧道二次衬砌的施工质量,从而保障隧道二次衬砌的安全性和耐久性。     

隧道衬砌防排水措施在防渗漏施工中的应用

通过分析隧道渗漏水现象，指出衬砌渗漏是关键因素，并详细阐述了“盲沟网”、防水板铺设及暗槽引水、堵漏止水等施工工艺，提出了解决隧道渗漏水的有效办法。     

大连地铁隧道的监控量测和数值模拟

针对大连地铁一期工程208标段交师区间隧道地表沉降位移、洞周收敛位移、拱顶沉降等进行了处理和分析,对隧道台阶法施工采用弹塑性分析方法进行数值模拟,并对围岩变形预测值与实际量测值进行了比较,分析误差产生的原因,对保证已有设施的安全和施工过程的安全具有重要的意义。