盾构隧道通用楔形管片排版系统的核心算法研究

盾构隧道通用楔形管片是通过前后两环的相对旋转来拟合线路中的直线和曲线要素,简化了模板设计,通用性强、质量容易保证。通用楔形管片拼装设计的关键是根据线路的平、竖曲线要素和偏差要求确定环宽和楔形量,而每一环衬砌的偏差计算是通过排版来实现的。文章对通用楔形管片排版的主要步骤和核心算法作了介绍,其中包括平、竖曲线上的坐标法定点算法、线路上理想点的二分法求值算法,以及空间任意点绕任意轴旋转的计算机图形学算法。文章最后介绍了一个盾构区间隧道的排版过程及结果。     

地铁砂卵石地层采用加泥式土压平衡盾构机的设备配置及顶推力检算

盾构设备配置是否合理是关系到工程建设成败、工程进度、工程投资的重要因素。在成都砂卵石地层中建设地铁,要求盾构设备能够实现砂卵石地层的长距离掘进、大漂石和卵石的破碎以及防止喷涌的发生。根据这些要求,阐述了某加泥式土压平衡盾构机的基本设备参数,并对其功能进行了分析,同时对设备配置中的顶推力参数进行了示例性检算。     

Experimental and Numerical Study on the Behaviors of Deep-Buried Water-Storage and Drainage Shield Tunnels北大核心CSCD

Deep-buried water-storage and drainage shield tunnels, which are different from road and subway shield tunnels in terms of computation theory, construction technology and operation maintenance, would bear high inner water pressure and large earth pressure. In view of the change of the bearing mode for the lining structure of water-storage and drainage shield tunnels, a full-ring test and numerical analysis are carried out to study the influence of inner water pressure, staggered joint assembly and bolt installation types on the behaviors of water-storage and drainage shield tunnels. The results show that the deformation of the straight-jointed water-storage and drainage shield tunnel varies greatly from the state of empty water to that of full water; and the vertical and horizontal convergence deformations of the tunnel with inner water pressure of 0.6 MPa are 2.2 times and 3.2 times of that without inner water pressure, respectively. The convergence deformation, and the maximum joint opening and bolt tension of stagger-jointed lining structure decrease by 15%-25% and 25%- 40%, respectively, compared with that of the straight-jointed water-storage and drainage shield tunnel. The bolts at the segmental joints will yield because of the increase of inner water pressure and the first occurrence of bolt yield phenomenon is located near the position on the lining structure which is under the action of maximum negative bending moment; because the failure of shield tunnel is always caused by the yield of joint bolts, this position is the weak point for the deep-buried water-storage and drainage shield tunnel. For the water-storage and drainage shield tunnel based on the connection with double rows of bolts, the bolts near the outer arc surface of segmental joints in the area of 90 degree in the vault and arch bottom can be removed; the bolts near the inner arc surface of the segmental joints within the 90 degree of the haunch must be installed, otherwise, the tensile force of the bolts at the segmental joint near the maximum negative bending moment will increase by 5%-14%. © 2018, Editorial Office of "Modern Tunnelling Technology". All right reserved.     

GIS-Based Grid Assessment Model of Shield Tunnel Conditions and Its Application北大核心CSCD

As the lack of guidancs for maintenance and repair of rail transit shield tunnels, this paper proposes a macroscopic method for grid assessment of shield tunnels. First, the tunnel serviceability index (TSI) is adopted as the tunnel condition assessment method and the results are compared with Chinese codes and the traditional fuzzy hierarchical comprehensive evaluation method. Second, based on the assumption that the factors affecting the conditions of the tunnels, such as the surrounding stratum environment, the structural overlying load and so on, are correlated spatially, the spatial variability theory is used for the grid assessment of shield tunnels. Finally, taking the Shanghai Rail Transit System as an example, the application results of the grid assessment method are described. © 2018, Editorial Office of "Modern Tunnelling Technology". All right reserved.     

Study on the Stress and Deformation Behaviors of a Deep and Irregular Foundation Pit as the Shield Launching Shaft in a Sea Reclaimed Cofferdam北大核心CSCD

With the development of the tunnel technology in China, the shield tunnel will become an important way to build the Sea-crossing channel. Taking the current largest diameter Shantou Bay shield tunnel in China as the engineering background, this paper introduces the challenges faced by the construction of the shield launching shaft in the reclamation cofferdam: e.g. deep, irregular excavation, deep silt layer and great influence of the seawater. Based on the practical conditions, a top-down construction technique of large ring beam considering two working conditions of foundation pit excavation and shield launching is proposed. Based on three-dimensional finite element analysis and field measurement, the stress characteristics and soil deformation of foundation pit are studied. The results show that the top-down construction technique of large ring beam can effectively control the deformation of the foundation pit and save construction time. © 2018, Editorial Office of "Modern Tunnelling Technology". All right reserved.     

Distribution Laws of Earth Pressure Acting on a Shield Tunnel Based on Measured Data北大核心CSCD

The earth pressure acting on a shield tunnel is intrinsically related to synchronous grouting, the position of the shield machines, the rigidity of the segment and stratum, etc. Existing theoretical formulas and empirical methods couldn′t exactly reflect the actual state of the segment of a shield tunnel during construction due to the com⁃plexities mentioned above. Based on earth pressure data measured at 52 monitoring sections in 35 tunnels, the distri⁃bution laws and influential factors are analyzed. The results show that: 1) the earth pressure scope is 0 to 400 kPa for over 90% of the total samples, but is recommended to be 0.3 to 0.4 MPa for the empirical grouting pressure; 2)the earth pressure on the segment and the buried depth approximately have an exponential relationship, with the dif⁃ference between the max. earth pressure and the stable earth pressure decreasing with an increase of the buried depth; 3) the lateral pressure coefficient range is 0.5 to 2.3, which is partially out of the scope of recommended values(0.5 to 1.0) of surrounding rock of grade Ⅵ, so it is not appropriate to follow the recommended values in the specifi⁃cation; 4) the relationship of the earth pressure and the segment/soil stiffness ratio presents a quadratic function, and the most reasonable value for the stiffness ratio of the segment/soil is 1.0; and 5) there are four typical stages of the spatial distribution of earth pressure on a segment in clay stratum—the erection stage, the grouting influence stage,the consolidation contraction stage and the recovery stage, with the distribution of the circumferential earth pressure being asymmetrical. The distribution curves of the earth and water pressure in sand and soil layers are classified as a“weak decay pulse fluctuation”and“double hump,”respectively. After stabilizing, the circumferential earth pressure is notably in a symmetrical distribution, and the water pressure exhibits a light bulb shaped distribution (large at the lower part and small at the upper part). These conclusions provide a reference for studying the mechanism of earth pressure functions and perfecting the design of segments for shield tunnelling. © 2018, Editorial Office of "Modern Tunnelling Technology". All right reserved.     

Study on Reinforcing Technology System for the Overlapped Running Shield Tunnels underneath the Track Group of High Speed Railways北大核心CSCD

The large settlements of tracks will emerge due to multiple disturbances in the construction of over- lapped shield tunnels, which affects the running safety of trains. Based on the overlapped Sungang station-Honghu station shield running tunnels of Shenzhen Metro line 7 passing underneath 26 tracks of high speed railways, a rein- forcement technology system consisting of”track support + subgrade reinforcement + interlayer soil consolidation + internal support of the lower tunnel”was developed. The settlements of tracks were mainly monitored automatically with manual monitoring as an auxiliary one. The results show that the maximum settlement of main track caused by constructing overlapped shield tunnels is -5.9 mm which is less than the control value of 10 mm, ensuring the opera- tion safety and verifying the reliability and practicability of the reinforcement technology system. © 2018, Editorial Office of "Modern Tunnelling Technology". All right reserved.     

武汉地铁越江盾构隧道纵向不均匀变形及力学特性研究

地铁盾构隧道,尤其是大型跨江海的水下地铁盾构隧道,局部埋深通常要大于普通地铁盾构隧道,而且要承受较高的水压力作用;盾构隧道作为特长线性结构,其纵向刚度较小,对于外部荷载的变化较为敏感,由此产生的不均匀变形是隧道工程中不可忽视的问题。文章针对武汉地铁越长江盾构隧道工程,通过三维数值计算探讨了埋深变化、水压变化、地层变化及穿越刚性结构物等因素对越江盾构隧道纵向不均匀变形及受力状态的影响。     

浅议盾构过矿山法隧道空推段施工质量控制

盾构在通过矿山法隧道施工过程中,因控制不当会产生一系列的质量问题。文章研究分析了现场施工表现出来的管片错台、隧道渗漏水、管片上浮、管片破损等质量缺陷及其形成原因,并阐述了预防和控制其质量缺陷的相关措施。     

盾构工程钢筋混凝土箱体辅助始发技术

在通过江、河等大埋深隧道工程中,盾构始发施工通常面临着涌水、涌沙等风险。文章针对工程特点,介绍了一种采用临时钢筋混凝土箱体辅助始发的工法,即盾构机先下井,修筑混凝土箱体并用回填土将盾构机密闭,使盾构从密闭箱体中始发,待盾构通过洞门后再补充注浆封堵洞门间隙。实践证明,该工法有效地降低了盾构始发涌水、涌沙的风险。