软岩隧道施工特性及其动态力学行为研究

采用三维快速有限差分软件，以软岩小净距隧道在不同施工方式下达到稳定后围岩和复合衬砌的力学效应为对象，重点分析不同施工方式下锚杆、喷射混凝土层的受力特点，以及洞周围岩特征点的变形和府力。对推荐的施工方式，分析了锚杆轴力、喷射混凝土层弯矩随开挖顺序的变化过程。计算结果表明：施工小净距隧道应慎重选择后继施工隧道的开挖方式，后继施工隧道的开挖方式直接对先行既有隧道锚杆、喷射混凝土层的应力状态产生很大影响。提出了复合衬砌应重点关注的薄弱部位和可能采取的工程措施。     

考虑治理荷载作用时井壁严格轴对称变形分析

为了研究约束内壁法治理井筒的力学效果,对特殊地层中井壁内侧处于约束状态的立井建立了严格轴对称弹性分析方法。通过线性叠加原理将相应应力边界分解为对称及反对称部分,利用两个子问题的对称性质,选择适当的级数形式的Love应力函数,应用双重级数展开法,侧面采用Fourier级数展开,端部采用Fourier-Bessel级数展开,通过对比正交系数的方法建立待定系数的方程组,联立求解方程组后获得了井壁满足所有侧面及端部边界条件的弹性解答。针对某井筒约束内壁治理给出算例,并应用第四强度理论研究了井壁的安全性,结果表明:约束段井壁内缘附近在约束后相当应力减小,安全性得到了有效的提高。     

On the sound insulation of masonry wall façades

In this paper, laboratory measurements of sound reduction index for two types of cavity walls commonly used in façades are presented. The first type consists of “masonry–air cavity–brick” and the second one consists of “masonry–air cavity–-gypsum board”. Data are used to show that masonry walls with gypsum boards provide higher sound insulation than masonry cavity walls. The influence on sound reduction index of apertures made on external leaf of the wall to ventilate the cavity of the wall is also examined.     

Full 3D modelling for effects of tunnelling on existing support systems in the Sydney region

The assessment of the interaction between a new tunnel and existing structures is an important issue in urban areas. In this study, the effect of tunnelling on the existing support system (i.e. shotcrete lining and rock bolts) of an adjacent tunnel is firstly investigated using ABAQUS and TUNNEL3D through full three-dimensional (3D) finite element calculations coupled with elasto-plastic material models, which takes into account the tunnelling procedure, the interaction between the shotcrete lining and rock mass, the interaction between the rock bolts and rock mass, and the elasto-plastic behaviour of the rock mass, the shotcrete lining and the rock bolts. Then, on the basis of the calculated results, it is concluded that the driving of the new tunnel significantly affects the existing support system when the advancing tunnel face passes the existing support system and is minor when the face is far from it. Moreover, the support system in the side of the existing tunnel closest to the new tunnel is more significantly affected than that on the side opposite to the new tunnel. It is also found that in a region such as Sydney with relatively high horizontal regional stresses, the driving of the new tunnel will not cause considerable adverse effects on the existing support system, if the new tunnel is driven horizontally parallel to the existing tunnel with a sufficient separation, since both the tensile stress in the existing shotcrete lining in the lateral sides of the preceding tunnel and the compressive stress at the crown decrease although noticeable tensile stress increments are observed on some parts of the existing rock bolts. Finally, it is pointed out that the effects of tunnelling on the existing support system strongly depend on the position between the original and new tunnels. In terms of the stress increments on the existing support system, especially the maximum tensile stress increments on the existing shotcrete lining, the driving of the new tunnel causes increasingly adverse effects on the existing support system in a sequence of: (i) horizontally parallel tunnels with a separation of 30 m; (ii) horizontally parallel tunnels with a separation of 20 m; (iii) staggered tunnels with a separation of 30 m; (iv) vertically alignment tunnels; and (v) staggered tunnels with a separation of 20 m in the cases investigated in this study. For the relatively high regional stresses in the Sydney region, the obtained results qualitatively agree with other’s published observations from the construction of closely parallel subway tunnels.     

武汉长江隧道管片衬砌结构力学特征模型试验研究

针对武汉长江隧道承受高水压和穿越高渗透性砂性土质的特点,在相似模型试验中专门采用盾构隧道-地层复合体模拟试验系统和旋转式水压装置共同作用,实现对水压和土压的分别控制加载,完成水土分算和水土合算的不同水土压力场条件下管片衬砌结构力学特征的模型试验,最后对高水压和变水压条件下的管片衬砌结构力学变化规律进行了分析。研究表明,高水压条件下的管片衬砌结构最大正负弯矩、最大变形量和结构偏心矩整体水平均有明显偏小,而平均轴力水平有明显提高;随着水压力加大,管片衬砌结构的平均轴力明显增大,最大正负弯矩略有增长或基本不变,最大偏心矩明显减小。该研究为武汉长江盾构隧道的衬砌结构设计提供有价值的参考。     

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.     

浅谈路缘石施工方法

从预制安装和现浇滑模施工两方面详细地介绍了路缘石的施工工艺,提出了路缘石的安装注意事项,比较了预制安装法和滑模施工方法,指出滑模施工是一种快捷、方便、经济、实用的路缘石施工新技术.     

盾构隧道纵向计算模型及其问题分析

针对盾构隧道纵向性能问题,将已有盾构隧道纵向结构计算模型进行了归纳,分析了各种模型的优缺点及其适用性,对纵向等效连续化模型中平截面假定的适用性问题和纵向螺栓的环向平均化问题进行了探讨。     

隧道衬砌混凝土裂缝原因分析及处理

结合沙峁沟隧道施工实例,对隧道衬砌混凝土裂缝的原因进行了分析,针对细微裂缝、贯通性裂缝、密集裂缝,提出了具体的裂缝处理措施,对相似条件下施工的隧道出现的裂缝有一定的参考价值。     

隧道二次衬砌施工方案的探讨

对隧道二次衬砌的概念、设计及施作时间进行了介绍,并从混凝土的制备、衬砌施工方法、衬砌一般规定等方面阐述了二次衬砌的施工,分析了其施工中常见的问题及处理方法,以供类似工程参考。