考虑多场耦合的碰撞载荷下水中悬浮隧道动力响应

水中悬浮隧道通过系泊系统使其悬浮在水下一定深度处,与潜器的碰撞可能会使隧道结构产生较大运动响应,呈现大幅度的非线性位移,会使隧道失去原有的稳定性甚至对隧道安全性产生较大的影响。因此,本文开展考虑多场耦合场景下碰撞载荷作用下,水中悬浮隧道的运动响应研究。通过与文献中试验结果的对比分析,验证数值模型的有效性。建立水中悬浮隧道及其系泊系统的三维运动模型,同时通过Abaqus建立水中悬浮隧道的碰撞场景与STAR-CCM+进行双向耦合联合仿真,开展水中悬浮隧道被潜器撞击后的运动响应研究,并分析不同碰撞场景下水中悬浮隧道的运动响应变化规律。     

水中悬浮隧道受撞击作用的数值分析

针对水中悬浮隧道在偶然状况下受到的潜艇撞击问题,文章采用流固耦合方法,建立了撞击作用下浮筒式悬浮隧道的有限元动态模型,分别撞击跨中、隧道四分之一跨、浮筒,分析隧道变形、撞击力、连接钢管拉杆力、隧道端部约束力、隧道动能情况。结果表明:撞击作用下,隧道整体变形明显,结构内力大。不同撞击位置处,悬浮隧道在水下的结构变形和受力行为区别明显。对此,有必要考虑撞击位置进行悬浮隧道的抗撞击设计。     

悬浮隧道水动力问题研究概述

悬浮隧道作为一种新型的跨水域交通方式近年来引起各国学者广泛的关注,文章在介绍悬浮隧道研究背景与各国发展状况的基础上,首先梳理了悬浮隧道断面形式与管体连接方式的相关研究,分析了不同断面形式的优缺点,概述了管段之间连接、支撑悬浮系统连接以及隧道两端连接的相关成果。文章重点围绕悬浮隧道水动力问题,系统梳理了针对悬浮隧道水动力荷载、不同荷载作用下的运动响应及锚索系统的涡激振动及其抑制问题的研究,最后通过总结前人的研究成果,提出了悬浮隧道水动力研究方面需要进一步关注的问题。     

水流作用下悬浮隧道耦合动力数值模拟分析

安装在深水区的悬浮隧道在水流作用下会产生交替脱落的漩涡,从而使得悬浮隧道受到周期性的力,进一步导致悬浮隧道产生涡激振动。当涡脱落频率与悬浮隧道固有频率相接近时会发生"锁定"现象,进而导致悬浮隧道发生振幅较大的运动,类似于结构的共振状态。文章利用有限元数值方法求解不可压缩粘性流体雷诺平均Navier-Stokes方程,并结合任意拉格朗日-欧拉(ALE)动网格方法,对不同雷诺数下(Re=1 000～100 000)悬浮隧道的涡激振动问题进行了数值模拟研究。计算中悬浮隧道受到弹簧和阻尼的约束,并允许其仅发生横流向的运动,研究了不同结构自振频率下悬浮隧道的受力和运动情况以及不同浮重比情况下悬浮隧道的受力和运动的结果。结果表明,在计算的各雷诺数下,悬浮隧道发生"锁定"的频率基本一致,但是悬浮隧道不同浮重比对"锁定"区间存在影响作用。     

随机波流作用下不同截面形式悬浮隧道的动力响应

悬浮隧道是一种用以跨越长深水域的新型交通结构物,其动力响应是评价其安全性的关键性指标。不同截面形式悬浮隧道具有不同的水动力特性,为研究不同截面形式的悬浮隧道在海洋真实随机波浪及均匀流荷载环境下的动力响应,基于势流理论建立悬浮隧道有限元模型。为了验证计算理论的准确性,将数值模拟结果与试验结果进行对比。结果表明,该计算理论具有较高的准确性,可用于进一步的悬浮隧道动力响应分析。对不同截面类型悬浮隧道在不同工况下动力响应进行分析,结果表明：椭圆形截面悬浮隧道对波流的敏感性最高,安全性最差;矩形截面与八边形截面在大多数情况下的动力响应较为接近,但八边形对于有义波高的敏感性更高一些。研究结果可为悬浮隧道建设提供有效的建议。     

正向规则波作用下悬浮隧道时域全局动力分析

应用Morison方程和有限元法，将悬浮隧道管体假定为与岸坡固定的Euler-Bernoulli梁结构，通过将锚索与悬浮隧道管体、海底平面铰接，实现了锚索、悬浮隧道管体以及岸坡三者之间的动力学耦合，将线性波浪理论应用于Morison方程计算波浪荷载，在时域内采用Newmark-β隐式时间积分法迭代求解悬浮隧道的运动控制方程，进而构建了水下悬浮隧道的三维动力学耦合数值模型。研究结果表明：在长周期波主导的海域，适当增大水平方向的系泊刚度，将有利于控制悬浮隧道整体的位移幅值；隧道近岸处的锚索由于边界条件的影响，在波浪条件下将承受更大的张力，工程中应适当增加或加粗近岸端部锚索，排除安全隐患；悬浮隧道的锚索布置间距宜固定在250～300 m的范围内。     

中国南海波浪作用下悬浮隧道运动响应研究

通过采用光滑粒子法求解弱可压流体运动方程，建立波浪-悬浮隧道-系泊系统全耦合时域分析模型，研究波浪对悬浮隧道耦合作用下的动力响应。基于中国南海实测海洋环境数据，对波浪作用下悬浮隧道的整体受力、运动响应及系泊受力进行研究。结果表明：受雷诺数影响，隧道受到的波浪力与波浪强度呈非线性关系；系泊缆与海床夹角越小，隧道的纵摇幅值越小；当角度为45°时，隧道运动性能及系泊缆受力能够达到较好的平衡状态。研究结果能为悬浮隧道选型及系泊系统设计提供参考。     

洋流作用下悬浮隧道动力学行为试验研究

本研究根据相似准则和试验条件设计试验模型。在试验模拟的1节悬浮隧道管段上分别布置2组和3组锚索支撑,测试在不同流速条件下,悬浮隧道管体结构的环向应变、轴向应变及张力腿锚索的轴力。根据试验结果,初步分析悬浮隧道应力的空间分布特征和张力腿的轴力情况;给出在相同环境条件下,张力腿锚索数量对结构应力的影响、洋流速度对悬浮隧道管段结构变形和张力腿轴力的影响关系等。     

波流作用下悬浮隧道局部锚索的破断动力响应

为研究波流作用下悬浮隧道局部锚索的破断动力响应,运用ANSYS/AQWA软件建立悬浮隧道及其锚泊系统的有限元模型.通过单元生死功能和时控法模拟锚索破断行为,对比分析不同波流条件对悬浮隧道局部锚索破断动力响应的影响.研究结果表明:锚索破断之后,会对剩余锚索产生冲击效应,缆力瞬态增量随着与破断位置距离的增加而逐步递减;规则波、均匀流和锚索破断作用引起的悬浮隧道动力响应具有不同的特征,规则波主要引起结构产生周期运动,均匀流主要引起结构产生大幅偏移和低频运动,锚索破断主要引起结构产生冲击效应和高频振动;锚索破断之后,剩余结构的阻尼增大、刚度降低,导致锚索破断前后的结构运动行为出现明显的不同.     

琼州海峡索桥式悬浮隧道方案的可行性研究

结合琼州海峡的海底地形地貌、气象、地质条件等因素,对跨海大桥、海底隧道、桥隧结合及悬浮隧道等方案进行比较分析,对这些方案的优点和不足进行了讨论。在此基础上,提出索桥式悬浮隧道方案,介绍了该方案的结构组成及其特点,从建造技术、经济指标、环境保护等方面探讨了索桥式悬浮隧道在琼州海峡通道中应用的可行性。研究认为,与其他方案相比,索桥式悬浮隧道具有结构新颖、受力明确、线路短、跨度大、经济指标高等优点,是一种较好的琼州海峡跨海方案。     

Design philosophy of floating bridges with emphasis on ways to ensure long life

The paper briefly outlines current design philosophies for floating bridges, with special reference to aspects that are deemed to be of interest in the context of very large floating structures. Since the design of submerged floating tunnels is done by people in the same milieu and deals with many of the same problems as in the design of floating bridges, while being in some respects more critical, some of the design philosophy of that subject is also included. The design philosophy and methodology for floating and submerged tunnel bridges draws heavily on Norwegian experiences in two large fields: offshore structures and conventional bridges.     

A coupled numerical approach to simulate the effect of earthquake frequency content on seismic behavior of submarine tunnel

Roughly 90% of all natural vibrations have epicenters in offshore zones and may cause destruction of submarine and floating structures. Such excitations can influence the safe performance of facilities set up on the seabed, like tunnels, jacket legs and subsea oil pipelines. Some researches on this theme have been carried out to demonstrate the importance of seaquake analyses and their effects have been underlined. The present study intends to numerically simulate a two-dimensional fluid-structure interaction (FSI) problem in order to examine the dynamic response of submarine tunnel under real horizontal earthquakes. Pressure is considered as independent nodal variables to represent the fluid flow effects and the induced time-dependent acceleration in porous medium equation is incorporated in the analysis and the tunnel shell is considered as flexible. This work highlights the importance of the input ground motion frequency content that governs the development of the induced seismic stress/strain around the lining of the tunnel. The results demonstrate that for deep sea the increment rate of the circumferential stress caused by surface gravity waves is below 7% when compared to the no-wave interface condition. Moreover, it is confirmed that long-period record may amplify the overall response of the system (up to 60%) specially the lateral and vertical displacements, as well as the principal stress to a lesser extent. The developed numerical model can attend to further analysis of tunnels embedded in a half-space in conjunction with fluid undergoing the severe long-period earthquakes.     

沉管隧道干坞方案比选

随着我国沉管法修建隧道技术的发展,越来越多的水下隧道采用沉管法施工,而干坞是沉管隧道修建的重要因素之一。通过对移动干坞方案和三种固定干坞方案进行综合比较,论述不同干坞方案在不同环境中的适用性及其优缺点,以确定经济、合理的干坞方案。     

Experimental and numerical study on dynamic responses of floating bridge under the shielding effect of a floating platform

A floating bridge and a floating platform can serve as a transport channel between land and sea. They will interact with each other in the wave environment. In this paper, the dynamic response characteristics of a floating bridge under irregular waves and regular waves are studied by means of model tests and numerical calculations. The results of model test and numerical calculation based on potential flow theory are basically consistent and can be mutually verified. By comparing and analyzing the dynamic response results of the floating bridge under the condition of “with floating platform” and “without floating platform”, some conclusions are drawn. The floating platform will have a shielding effect on waves coming from the sea. Due to the shielding effect of the floating platform, the motions in heave, surge and pitch of the floating bridge are evidently diminished. Among them, the motion response of the pontoon near the floating platform decreases most obviously. The floating platform provides a relatively stable marine environment for the floating bridge, thereby improving the survival state of the floating bridge.     

隧道二次衬砌背后脱空的防治

文章介绍了隧道衬砌背后脱空治理的必要性及检测方法,进行了成因分析和对脱空的处理。结合工程实践经验从施工和管理角度提出了防治的具体措施,对施工中减小二衬脱空具有指导意义。     

浮船坞沉浮自动控制系统的设计和实现

为了提高浮船坞的自动化程度,本文针对某浮船坞,开发了浮船坞沉浮自动控制系统,主要对系统的总体设计、控制程序和监控软件进行了详细阐述。通过在浮船坞上的实际应用表明：浮船坞沉浮自动控制系统能够使浮船坞的沉浮过程更可靠、更快捷、更平稳。     

沉埋管隧道的施工技术及发展趋势

隧道作为一种更加便捷、安全的穿越江、河、湖、海的交通工程之一,有不受外界气候、风雨、波浪、水流、冰凌、大雾等因素影响的诸多优势。文章介绍了沉埋管隧道在世界各个国家和地区的分布情况及其主要原理和施工工艺,并就其发展趋势作了阐述。     

粤东地区公路隧道的防水技术

针对粤东地区地质、气候条件情况,结合公路隧道的防水原则,探讨该地区公路隧道的防水形式以及保证防水质量的施工措施。     

小间距隧道施工技术浅析

文章主要介绍广东西部沿海高速公路珠海段第三合同段大尖岭隧道施工技术和工法。施工中顺利地解决了隧道线间距小、洞口段浅埋偏压严重等技术难题,在质量、安全、经济等方面都取得了较好的效果。     

Hydroelastic responses and interactions of floating fuel storage modules placed side-by-side with floating breakwaters

This paper is concerned with the hydroelastic responses and hydrodynamic interactions of two large floating fuel storage modules placed side-by-side with the presence of floating breakwaters. These modules and breakwaters form the floating fuel storage facility (FFSF). The floating storage modules and breakwaters are modeled as plates and the linear wave theory is used to model the water waves in the numerical model. The numerical model is verified with existing numerical results and validated with experimental test. Numerical simulations are performed to determine the hydroelastic behavior and hydrodynamic interactions of floating storage modules placed adjacent to each other and enclosed by floating breakwaters under various incident wave angles. The effects of breakwaters, drafts, channel spacing formed by the two adjacent modules and water depth on the hydroelastic responses of the modules are investigated. The wave induced responses of multiple floating storage modules enclosed by floating breakwaters are also examined.