前排桩对桥墩周围水流及船舶影响研究

发布时间：2018-06-08 01:14

本文选题：船舶受力 + 前排桩　；参考：《长沙理工大学》2015年硕士论文

【摘要】：桥梁建设加强了江河两岸沟通和交流,促进了社会经济的发展。然而一些桥墩布置在通航水域中,绕经桥墩水流受边界影响出现局部流态,对船舶正常航行产生不利影响,可能妨碍通航并影响桥梁的安全。对于桥墩周围水流的研究成果已经较为丰富,但是对桥区航行船舶的受力问题还缺乏系统的研究。本文从船舶受力的角度分析探讨桥区航道船舶通航安全问题,提出改善船舶航行条件的措施,对保障桥区附近水域的通航安全及桥梁本身的安全具有重要意义。采用RNG、k-ε紊流模型对通航水域的桥墩单墩以及受前排桩保护桥增的周围流场进行数值模拟。采用测力天平测量仪以及应变应力采集系统,测量桥墩单墩周围船舶平面受力状况,并进一步测量不同前排桩布置工况下桥桩周围船舶平面受力状况。通过分析,得出主要结论如下:1、前排桩的设置,改善了桥墩局部水流结构和桥墩周围流场。当上游来流遇到前排桩T,水流受桩的引导产生偏离和分流,前排桩的分流作用将水流分向桥墩两侧,减缓水流对桥墩的直接作用,降低了墩前雍水,桥墩两侧水流得到平缓,同T在桩后形成一个低速尾流区域。受桩后尾流减速的影响,墩前行进水流动量减小,桥墩墩前横流相应减小,桥墩周围通航条件得到改善。2、前排桩改善效果通航条件的作用与前排桩的相关因素有关,涉及前排桩数量,前排桩与桥墩间距离等因素有关。在桥桩距卡相等的工况下,随着桩数增加,桩后尾流减速区域越大,桥墩周围不安全通航区域改善越明显。在桩数一定的工况下,前排桩尾流减速区域效果与桥桩距离有关,桥桩距太小,前排桩对墩前行进流速减缓不够充足;桥桩距太大,前排桩对墩前行进流速减缓效果减弱。3、船体平面受力在船体中心与桥墩中心交会区域附近达到最大,且船体所受横向力在船舶与桥墩交会过程中受力方向会发生两次转变。船舶平面受力的变化与水流流速正相关,船舶的平面受力峰值及分布区域不因水深改变而改变。船舶在桥墩周围时,船舶所受纵向力和横向力峰值随流速增大而增大,且船舶所受横向吸附力的分布区间随着流速增大而向下游发展4、本文以船舶沿水流横向受力变化曲线变化率近似为零边界为桥墩对船舶受力影响边界,桥墩到船舶受力影响边界的距离定义为船舶通航影响宽度。桥墩对船舶通航影响宽度与流速成正相关,即桥墩对船舶受力影响宽度随流速增大而增大。仅本文研究水流条件下,桥墩对船舶受力的影响宽度不超过2.8倍桥墩墩宽。5.船舶在前排桩区域附近时,船舶平面受力出现变化,但是总体变化不大。前排桩本身对船舶受力影响远小于桥墩对船舶受力的影响。前排桩的设置对船舶纵向受力突增和横向吸附力有减小的作用。2倍墩宽桥桩距、三桩数量工况下,前排桩对船舶受力改善效果最佳。
[Abstract]:Bridge construction has strengthened communication and exchange between the two sides of the river and promoted social and economic development. However, some piers are arranged in navigable waters, and the local flow around the pier is affected by the boundary, which has adverse effects on the normal navigation of ships, which may hinder navigation and affect the safety of bridges. The research results of the flow around the bridge pier have been rich, but there is no systematic research on the force problem of the navigating ship in the bridge area. In this paper, the problem of navigation safety in waterway in bridge area is analyzed and discussed from the point of view of ship force, and the measures to improve the navigation conditions of ships are put forward, which is of great significance to ensure the navigation safety in the waters near the bridge area and the safety of the bridge itself. RNG k- 蔚 turbulence model is used to numerically simulate the flow field of single pier of bridge piers in navigable waters and the increased flow field of bridge protected by front row piles. Using the force balance measuring instrument and the strain and stress collecting system, the plane stress state of the ship around the single pier of the bridge pier is measured, and the plane stress condition of the ship around the bridge pile under different conditions of the front row pile arrangement is further measured. Through the analysis, the main conclusions are as follows: 1, the arrangement of the front row pile improves the local flow structure of the pier and the flow field around the pier. When the upstream flow meets the front pile T, the flow of water deviates and distributes under the guidance of the pile. The distributary effect of the front row pile divides the water flow to the two sides of the pier, which slows down the direct effect of the water flow on the pier, reduces the uvula in front of the pier, and the flow of water on both sides of the pier is flattened. A low velocity wake region is formed behind the pile with T. Influenced by the deceleration of wake flow after the pile, the influent flow momentum before the pier decreases, the cross flow in front of the pier decreases accordingly, the navigation conditions around the pier are improved by .2.The effect of improving the navigation condition of the front row pile is related to the related factors of the front row pile. The number of front piles and the distance between front piles and piers are related. With the increase of pile number, the larger the deceleration area of wake flow behind the pile is, the more obvious the improvement of unsafe navigation area around the pier is. Under certain working conditions, the effect of wake deceleration zone of front row pile is related to the distance of bridge pile, the distance of bridge pile is too small, the velocity of moving velocity of front row pile is not enough, the distance of bridge pile is too large, The deceleration effect of the front row pile on the velocity of moving forward of the pier is weakened. 3. The plane force of the hull reaches the maximum near the intersection area between the hull center and the pier, and the transverse force of the hull changes twice during the course of the intersection between the ship and the pier. The variation of ship plane force is positively related to the flow velocity, and the peak value and distribution area of ship plane force are not changed by the change of water depth. When the ship is around the pier, the peak value of the longitudinal and transverse forces on the ship increases with the increase of the velocity. With the increase of the velocity of the ship, the distribution range of the transverse adsorption force on the ship develops downstream. In this paper, the change rate of the lateral force curve of the ship along the water flow is approximately zero boundary as the influence boundary of the bridge pier on the ship force. The distance from the pier to the force-bearing boundary of the ship is defined as the width of the ship's navigable influence. The influence width of piers on ship navigation is positively related to the velocity of the ship, that is, the influence width of the pier on the ship increases with the increase of the velocity. Only in this paper, under the condition of water flow, the influence of bridge piers on ship force is not more than 2.8 times the width of piers. When the ship is near the front row pile area, the plane force of the ship changes, but the overall change is not significant. The influence of front pile itself on ship force is much smaller than that of bridge pier. The installation of the front row pile has the function of decreasing the longitudinal force and the lateral adsorption force of the ship. 2 times the pile distance of the wide bridge with piers. Under the working conditions of three piles, the effect of the front row pile on the ship's force improvement is the best.
【学位授予单位】：长沙理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U442.3

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