砂卵石地层台阶法施工隧道围岩-支护结构应力应变特性三维离散元分析

为了解砂卵石地层隧道围岩和支护结构的应力应变特性，以青海循隆高速公伯峡隧道为依托，借助PFC3D离散元软件对公伯峡隧道穿越砂卵石地层进行三维模拟，重点研究以密排短管棚预支护为根本前提，以三台阶预留核心土为施工方法的砂卵石地层围岩和支护结构的应力应变特性，并与现场实测进行对比分析。研究结果表明： 隧道台阶开挖时，围岩应力集中范围逐渐从拱顶过渡到拱腰，直到拱脚，对应的塑性区范围不断扩大，且密排短管棚对塑性区的发展有一定的“遮拦效应”； 围岩横纵向变形规律一致，主要是向隧道临空面产生收敛变形，且密排短管棚形成的梁拱效应限制了掌子面前方位移发展； 2种方法得到的初期支护变形规律一致，均呈阶段性变化，拱顶下沉累计值大于周边收敛累计值，且两者的最终变形量均满足规范限值要求。     

回火退火法在直臂架滑轮组补偿变幅系统优化设计中的应用

采用一种改进的模拟退火法－回火退火法对对滑轮组补偿式变幅系统的设计参数进行了优化,算法具有全局寻优能力,并提出了模拟退火法的收敛速度,将其计算结果与传统设计结果进行了比较,设计参数得到了较好的优化。     

探析水库除险加固工程帷幕灌浆设计及施工

结合工程实例,首先介绍了水库除险加固工程帷幕灌浆设计,随后就工程施工工艺以及相关注意事项进行了说明,仅供参考。     

独柱独桩式桥墩在山区高速公路中的应用

文章结合具体工程,针对该工程位于坡面上的桥墩对山体破坏较大,位于河道中的桥墩增加桥墩阻水作用的问题,在桥梁下部构造大范围采用了独柱独桩结构,主要研究了其尺寸拟定及结构验算、独柱式独桩桥墩防撞受力计算等内容,对独柱独桩式桥墩的优势与不足之处进行分析,不仅减少了工程量,规避了工程风险,而且减少了山体开挖,减轻了对环境的破坏。     

Main Construction Technical Difficulties and Solutions of  Shenzhen Chunfeng Tunnel（深圳春风隧道主要施工技术难题与解决方案）

Shenzhen Chunfeng Tunnel is one of the shield tunnels under construction with the largest diameter in mainland of China. The whole tunnel passes through the coastal composite stratum, with rock from broken to integral, and the strength of some sections reaches 173 MPa. The tunnel under crosses the railway, subway, bridge and multiple buildings closely in a complex and sensitive environment. Combining the stratum situation and characteristics of large diameter shield machine, the problems that will be faced during the construction process, including low rock breaking efficiency of shield machine, discharge stagnation and jamming of the chamber, settlement control in sensitive environment, and impact of large diameter shield segment floating, cracking and construction on urban traffic, are analyzed. Based on the engineering experience, the following solutions are proposed: a shield rock breaking efficiency solution for the complete extremely hard rock section, settlement control measures for adjacent buildings and structures of shield driven tunnels, solutions for jamming and discharge stagnation of large diameter slurry shield, comprehensive measures for prevention and control of shield segment floating and cracking, and a slag treatment plan for downtown areas. Chunfeng Tunnel tests the wisdom of Chinese builders with its tremendous volume and strict construction standards, and it also has certain reference significance for other similar projects.     

基于分布式压密传感器的隧道衬砌防脱空主动监测

为解决二次衬砌脱空的问题，实现在浇筑过程中对衬砌脱空的主动监测，结合隧道二次衬砌衬背脱空的成因，研发基于分布式压密传感器的隧道衬砌脱空主动监测系统。该系统由分布式压密传感带、延长线、直显终端及工业电脑组成，具有原理简单、安装便捷等优点。通过在衬砌层间预埋分布式压密传感器，对浇筑过程进行主动监测，结合带模注浆技术，实现对衬砌脱空的精准注浆与快速处治，有效解决隧道衬砌脱空问题。在验证试验中，系统在浇筑过程中共发现2处拱顶空洞，证明该系统对脱空监测的有效性。同时，该系统在国内部分重点铁路线已经取得应用，现场应用情况表明，该系统对二次衬砌拱顶脱空的识别准确率可达到95.5%。     

Innovation and Practice of Parallel Dual mode Slurry/EPB Shield Construction Technology and Freezing Cutterhead Opening Technology（并联式泥水/土压双模式盾构施工技术与冷冻刀盘开舱技术的创新与实践）

Two major concerns have been drawn in the process of shield construction: one is the difficulty in selecting a shield machine; the other is the high risk of opening for cutterhead changing. Based on the existing shield systems, a parallel dual mode shield with freezing cutterhead is developed by optimising internal structure and equipment and carrying the freezing device. The dual mode shield construction technology and freezing cutterhead technology are successfully carried out on project cases including Guangzhou Metro Line 9, Guangzhou Metro Line 21 and 220 kV Shijing Huanxi Electric Tunnel (Xiwan Road Shisha Road Section). The parallel dual mode slurry/EPB shield not only has the functions and advantages of slurry shield and EPB shield but also can switch into slurry/EPB mode for different strata and environments easily. Thus, it can achieve rapid shield tunneling. By combining the shield with the freezing system, the soil around cutterhead can be frozen to provide conditions for chamber opening under atmospheric condition. Meanwhile, it is also compatible with dual mode shield.     

308000 DWT超大型油船舵叶工艺设计

本文主要介绍VLCC船舵叶建造工艺和施工要领以及精度控制等方面采取的措施。     

圆形钢筋混凝土桩局部破除后抗弯能力计算及应用

深基坑工程中常常出现围护桩成桩垂直度偏差以致侵入主体结构限界的现象，为保证后续主体结构尺寸符合要求，需要对侵限部位进行凿除，进而导致其抗弯承载能力下降。针对圆截面桩体局部凿除后的抗弯承载能力计算问题，基于二次逼近法，建立圆形钢筋混凝土桩局部破除后正截面抗弯承载能力计算方法，结合实际工程分析围护桩局部破除后对基坑围护结构体系的安全性影响。结果表明： 桩身局部破除后，纵向受力钢筋切断和桩身截面面积的减小将导致桩身正截面抗弯能力快速下降；依托工程中800 mm 的围护桩，凿除18 cm 厚度（含切断6根主筋）后，其正截面抗弯能力下降至原设计值的55%，剩余承载力已不能满足安全支护的要求，需进行加固处理。