Numerical study of the depth and cross-sectional shape of tunnel under surface explosion

Recently, blasting loads have come into consideration because of the large number of intentional or unintentional events that affected important structures around the world, obviously indicating that the topic is relevant for purposes of structural design and reliability analysis. This paper has evaluated the dynamic responses of buried tunnel in depths of 3.5, 7, 10.5 and 14 m for surface detonation of 1000 kg TNT charge in a surrounding sandy soil. The Kobe box shape subway tunnel was used as an example to evaluate and compare with semi ellipse, circular and horseshoe shape tunnel. The finite element software LS-DYNA has been used to model and to analyze the outcome of this project, specifically to be modeled in the area of the second interaction due to explosion. The results indicate that the circular and horseshoe tunnels are less resistant to demolition than the box shape tunnel however the semi ellipse tunnel is more resistant than the box shape tunnel.     

超浅埋地下通道暗挖法施工地表沉降监测分析

以合肥市府广场地下通道工程为实例,对施工过程中地表沉降监控量测技术进行了详细介绍,并通过对施工阶段监测数据的分析,总结在浅埋暗挖法施工过程中沉降规律。所得监测数据和监测经验对合肥地区类似地下工程具有一定的指导意义。     

软土流变特性试验研究

根据室内三轴流变试验的结果,研究了北京地区粉质粘土的流变特性。结果表明,该类软土具有较明显的变形时效性及其在不同应力水平下的蠕变特性。通过分析蠕变曲线的规律,选择了广义开尔文五单元理论模型和时间硬化经验蠕变公式来描述软土的流变特性,并达到了良好的精度,建立了适合北京地区典型软土的流变理论模型和经验模型。     

房屋为什么需要机械通风系统

文章具体解释了房屋为什么需要机械通风,并站在设计和安装的立场上分析了一个理想系统应具备的主要特征。     

杭州湾跨海大桥施工中的高程测量控制技术

文章结合杭州湾跨海大桥工程施工实践。介绍了综合应用GPS高程、全站仪三角高程和几何水准测量的高程测量控制技术,目的是满足风大浪高等恶劣施工环境中的跨海大桥高程控制测量及其高程施工放样的精度，取得了理想的效果。     

体外预应力混凝土梁的特点及极限强度分析探讨

文章讨论了体外预应力混凝土结构的特点,综述了各不同规范规程有关外荷载作用下体外预应力筋应力增量计算的一些规定,并讨论了这些方法的特点及存在的缺陷,最后讨论了极限承载能力计算的问题。     

柳州三门江大桥斜拉索施工技术

柳州三门江大桥主桥为双塔、双索面、三跨部分斜拉预应力混凝土箱梁桥。介绍了主桥斜拉索的体系构造、总体施工方案、施工方法、索力监控方法、施工工艺及施工要点等,对斜拉索施工中的注意事项进行了较详细的阐述。     

建筑企业员工培训的误区与对策探讨

企业培训是企业人力资源管理的重要内容,对企业的发展起着至关重要的作用。但是,我国建筑企业员工培训的现状并不乐观,仍存在很多问题。主要原因在于企业对员工培训的需求分析不到位,只重视企业的发展需求,而忽视员工个人的培训需求。在原因分析的基础上找寻解决问题的有效策略,提高我国建筑企业员工培训工作的质量,促进我国建筑企业的可持续发展。     

Response of segmented bored transit tunnels to surface blast

Increasing threat of terrorism highlights the importance of enhancing the resilience of underground tunnels to all hazards. This paper develops, applies and compares the Arbitrary Lagrangian Eulerian (ALE) and Smooth Particle Hydrodynamics (SPH) techniques to treat the response of buried tunnels to surface explosions. The results and outcomes of the two techniques were compared, along with results from existing test data. The comparison shows that the ALE technique is a better method for describing the tunnel response for above ground explosion with regards to modeling accuracy and computational efficiency. The ALE technique was then applied to treat the blast response of different types of segmented bored tunnels buried in dry sand. Results indicate that the most used modern ring type segmented tunnels were more flexible for in-plane response, however, they suffered permanent drifts between the rings. Hexagonal segmented tunnels responded with negligible drifts in the longitudinal direction, but the magnitudes of in-plane drifts were large and hence hazardous for the tunnel. Interlocking segmented tunnels suffered from permanent drifts in both the longitudinal and transverse directions. Multi-surface radial joints in both the hexagonal and interlocking segments affected the flexibility of the tunnel in the transverse direction. The findings offer significant new information in the behavior of segmented bored tunnels to guide their future implementation in civil engineering applications.     

独塔单索面部分斜拉桥非对称施工技术

依托余姚中山路斜拉桥项目,针对独塔单索面部分斜拉桥的结构特点,并结合该桥的周围环境,主桥主梁采用支架现浇和悬臂浇筑结合的非对称施工方法.根据悬臂现浇对称性施工原则和力学原理,建立不利条件下一侧挂篮一侧支架法现浇施工的新工艺,在支架侧先行施工一个节段,为菱形挂篮提供配重,经过体内预应力和体外斜拉索张拉,可有效保证结构安全...