狄洛尼三角网构建的目标点快速定位     

武鹏 《测绘科学》2016,41(1):154-157,88

针对在狄洛尼三角网构建中现有的目标点定位方法存在算法不够稳定、定位路径不惟一等问题,该文在重心方向定位算法的基础上研究建立一种沿搜索方向移动重心的快速定位方法:当发生目标点与当前重心连线经过三角形顶点或者与某三角形边重合等特殊情况时,利用三角形间的拓扑关系得到下一搜索三角形,以此三角形的重心代替前一重心与目标点构成新的搜索方向,继续搜索,从而解决切点问题;同时采用混合积判定公式确定两条线段的相交关系。仿真实验证明改进方法的定位路径惟一,而且可以大大提高构网效率,算法更稳健。  相似文献   

Improved assessments of wave-induced fatigue for free spanning pipelines     

《Applied Ocean Research》2016

For subsea pipeline projects, the costs related to seabed correction and free span intervention are often considerable. Development of reliable methods for fatigue analyses of pipelines in free spans contributes to minimize costs without compromising pipeline integrity. Assessment of wave-induced fatigue damage on multi-span pipelines is investigated, and improved analysis methods are suggested in this paper. A time-domain (TD) algorithm is developed, which accounts for non-linear hydrodynamic loading and dynamic interaction between adjacent spans. The proposed TD approach is employed to evaluate linearized frequency-domain (FD) solutions from recognized design standards and to study the dynamic response of multi-span pipelines to direct wave loading. Differences between multi- and single-span analyses are described for the first time, and the common assumption that the main fatigue damage contribution comes from the fundamental mode is demonstrated not to hold for multi-spans. An improved FD solution capable of predicting multi-mode response is derived and demonstrated to give accurate fatigue life estimates for multi-span pipelines.  相似文献   

Safety Assessment of Buried Pipeline during Pile Driving Vibration in Offshore Engineering     

Jingbo Su  Jianfeng Li  Ruihu Zhu  Wanggen Qin  Qiu Zhai 《Marine Georesources & Geotechnology》2016,34(7):689-702

To assess the impact of pile driving on adjacent submarine pipelines during the reconstruction of a pier berth, the local damage model of submarine pipelines is established to explore the safety thresholds of the particle peak velocity and horizontal displacement. The results are analyzed and adjusted by the existing standards and the corresponding literatures. Then, a three-dimensional numerical model is presented to assess the feasibility of the construction of piles by the obtained safety limits, in which the nonlinear behavior of the soil and stress–seepage coupling analysis are considered. After the construction, the safety of submarine pipelines is rechecked by the measured value of the particle peak velocity and horizontal displacement. Meanwhile, the propagation law of vibration, the horizontal displacement of underground soil, and the pore pressure during pile driving are explored. The results indicate that the construction of piles of 2# mooring pier did not cause damage to adjacent submarine pipelines. However, the construction of piles of 1# mooring pier which is nearer may cause damage to submarine pipelines.  相似文献   

鲁东地区地热资源分布规律及勘查定井方法探讨   总被引：1，自引：1，他引：0       下载免费PDF全文

崔煜烽  张杰  殷焘  史猛  毕建新 《中国地质调查》2018,5(2):86-92

鲁东地区具有丰富的地热资源,在地热勘查、开发和利用中,对地热勘查定井方法的选择至关重要。在介绍鲁东地区地热资源分布特征和赋存规律的基础上,结合鲁东地区地热勘查及施工的经验和教训,针对不同的地热地质条件,分别采用天然电场选频、瞬变电磁法(TEM)测深、可控源音频大地电磁测深(CSAMT)、电磁测深和自然放射能测深等方法对鲁东地区典型地热勘查区进行地热井位确定,并对勘查定井方法效果进行对比。结果表明: 鲁东地热资源主要分布在NE向、NNE向及NW向断裂交汇带附近,为断裂控制的深循环对流型带状地热资源,热储分布主要受断裂控制,勘查定井宜选择在2条或多条断裂的交汇处; 天然电场选频、瞬变电磁法测深对于浅部地层和断裂具有较好的反映; 可控源音频大地电磁测深对断裂深部发育特征反映明显,为鲁东地热勘查定井较适宜的方法; 地热勘查定井宜采用2种以上的勘查方法,避免在物探施工过程中受外在因素的影响。  相似文献   

考虑土体固液二相性质的地下管线地震反应研究     

艾晓秋  李杰 《地震工程与工程振动》2005,25(2):136-140

本文将管线周围的土体视为固-液二相介质，采用考虑地震过程中土体内孔隙水压力的增长和消散的有效应力分析方法，并以非线性的土体本构模型模拟土体动力特性的改变以及在孔隙水压作用下的变形，以求接近土体的真实地震反应。研究表明随着土体软化程度的不同，受到土体约束的管线应力亦发生相应变化。文中详细研究了地震动峰值、管线直径、行波波速和入射角度等对管线应力的影响。  相似文献   

A non‐baseline algorithm for damage locating in flexural structures using dynamic distributed macro‐strain responses     

S. Z. Li  Z. S. Wu 《地震工程与结构动力学》2007,36(9):1109-1125

The concept of distributed strain‐sensing techniques has been proposed in our recent research, which was dedicated to utilizing the strain distributions throughout the full or partial areas of structures to detect arbitrary and unforeseen damage. An algorithm not requiring a detailed analytical model is presented for damage locating in flexural structures through the direct use of dynamic responses recorded by distributed long‐gauge strain sensors. The modal macro‐strain vector (MMSV), which has been proven to have a mapping relation with displacement mode shape, can be extracted directly from macro‐strain time‐series data, from which a damage evaluating index can be derived and used as an indicator for locating damage. Numerical examples are simulated to verify the sensitivity and effectiveness of the index in different cases. Furthermore, experimental investigations on a cantilevered beam with various long‐gauge fibre optic sensors placements are carried out to examine the feasibility and applicability of the proposed method. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

非开挖导向钻进铺管技术穿越含砂卵砾石河流的施工实践   总被引：2，自引：0，他引：2  

王银献  刘国伟  谭志翔 《地质与勘探》2002,38(5):86-88

根据工程实例 ,阐述了非开挖导向钻进铺管技术穿越含砂卵砾石地层的施工工艺技术及施工中出现的问题 ,提出了解决这些问题的各种技术措施。  相似文献   

相位激发极化法应用研究   总被引：1，自引：0，他引：1  

刘瑞德  黄力军  陆桂福 《物探化探计算技术》2006,28(3):197-200

相位激发极化法是一种频率域激发极化方法,可直接测量电场电压与供电电流之间的绝对相位差。由于该方法对仪器精度要求较高,因而国内有关实际应用方面的资料相对较少。在金属矿产勘查中,目前国内大多采用时间域激发极化方法,测量岩矿石的极化率或充电率。虽然频率域激发极化法也有应用,但主要采用双频或多频测量,利用视频散率参数进行解释,野外测量工作量较大,测量精度相对较低。近几年,利用相位激发极化法在科研、生产中做了一些工作,这里介绍相位激发极化法模型试验及数据反演结果,岩矿石标本时间域(充电率)和频率域(相位)测试对比结果,以及实际应用实例及数据反演结果。应用结果表明,用相位激发极化法在矿产勘查中可以取得较好的勘察效果,并能在今后的工作中发挥更大的作用。  相似文献   

地下管线普查产品的检验   总被引：1，自引：0，他引：1  

顾建祥  钱小伟 《测绘与空间地理信息》2007,30(3):211-214

随着城市地下管线在城市管理、规划及建设发展过程中重要性的逐渐体现,越来越多的城市开展了地下管线普查,但其质量检验与质量评定方法却相对滞后,本文结合实例阐述了地下管线普查产品的检验及质量评定方法,供大家参考。  相似文献   

首都圈数字地震台网交互处理系统的定位稳定性探讨     

刘丽  毛国良  季爱东  赵英萍  李津津 《华北地震科学》2007,25(2):55-64

选取了2003年1月~2004年4月河北省及邻省ML≥2.0级地震149个,针对每个地震记录的具体情况,综合考虑最大空隙角、近台距离、远台距离、台数等因素,选取台站分布相对合理的4~12个台站,利用首都圈数字地震台网交互处理系统提供的Hypo81、GELor-p、Genetic3种定位方法分别进行定位处理,将3种定位结果与全国地震月报目录进行对比得到定位偏差量,定量分析了3种定位方法的定位偏差量随空隙角的变化,探讨了Hypo81、GELor-p、Genetic3种定位方法的定位效果、稳定性及适用性。  相似文献