Seismic response and correlation analysis of a pile-supported wharf to near-fault pulse-like ground motions

Earthquake investigations have shown that near-fault pulse-like(NF-P)ground motions have unique characteristics compared to near-fault non-pulse-like(NF-NP)and far-field(FF)ground motions.It is necessary to study the seismic response of pile-supported wharf(PSW)structures under NF-P ground motions.In this study,a three-dimensional finite element numerical model is created to simulate a PSW.By imparting three types of ground motion,the engineering demand parameters(EDPs)of PSW under NF-P ground motions were analyzed and compared,in which EDPs are the maximum displacement and bending moment of the piles.Twenty intensity measures(IMs)were selected to characterize the properties of ground motions.The correlation between IMs and EDPs was explored.The results show that the piles present larger displacement and bending moment under NF-P ground motions compared to NF-NP and FF ground motions.None of the IMs have a high correlation with EDPs under NF-P ground motions,and these IMs are more applicable to FF ground motions.The correlation coefficients between EDPs and IMs under three types of ground motion were obtained,which will provide a valuable reference for the seismic design of PSWs.

Behaviors of pile-supported embankments in highway engineering

Based on the variational approach for pile groups embedded in soil modeled using a load-transfer curve method, a practical method was conducted to estimate the settlement of symmetric pile group supported embankments. The working mechanism of composite foundations improved by rigid or semi-rigid columns is analyzed by this method. Under equivalent strain conditions, the pile-soil stress ratio approaches the pile-soil modulus ratio up to a limited value of pile stiffness （Rm〈10）; in the subsequent stages of high pile stiffness （Rm〉10）, a further increase in the pile-soil modulus ratio cannot lead to a significant increase of stress transferred to the columns in composite foundations. The major influencing factor of the stress concentration from soil to pile in a high pile-soil modulus ratio is the padding stiffness. For the composite foundation improved by cement mixing columns, the effective column length is about 15 to 20 m and it is a more economical and effective design when the column length is less than 15 m.

Numerical Analysis of Interaction Between Pile-Supported Pier and Bank Slope

Two and three-dimensional finite element analysis programs for pile-soil interaction are compiled. Duncan-Chang's Model is used. The construction sequence of the pier is modeled. The pile-soil interface element is used. The influence of the combination type of piles on the deformation of bank slope and pile behaviour is analyzed. Different designs of a pile-supported pier are compared thoroughly. Calculation results show that the stresses and displacements of the pile are directly related to the distance from the bank slope and the direction of inclination. An inclined prop pile set in the rear platform would remarkably reduce the stresses of piles and the displacement of the pier.

Analysis of ground vibrations induced by high-speed train moving on pile-supported subgrade using three-dimensional FEM

The pile-supported subgrade has been widely used in high-speed railway construction in China.To investigate the ground vibrations of such composite foundation subjected to moving loads induced by high-speed trains(HSTs),three-dimensional(3D)finite element method(FEM)models involving the pile,pile cap and cushion are established.Validation of the proposed model is conducted through comparison of model predictions with the field measurements.On this basis,ground vibrations generated by HSTs under different train speeds as well as the ground vibration attenuation with the distance away from the track centerline are investigated.In addition,the effects of piles and pile elastic modulus on ground vibrations are well studied.Results show that the pile-reinforcement of the subgrade could significantly contribute to the reduction of ground vibrations.In particular,the increase of elastic modulus of pile could lead to consistent reduction of ground vibrations.However,when the pile elastic modulus is beyond 10 GPa,this benefit of pile-reinforcement on vibration isolation can hardly be increased further.

Comparative analysis of seismic response characteristics of pile-supported structure

In order to analyze the seismic response characteristics of pile-supported structure,a computational model considering pile-soil-structure interaction effect was established by finite element method.Then,numerical implementation was made in time domain.At the same time,a simplified approximation for seismic response analysis of pile-soil-structure system was briefly presented.Furthermore,comparative study was performed for an engineering example.Through comparative analysis,it is shown that the results obtained by the simplified method well agree with those achieved by the finite element method.These results show that spectrum characteristics and intensity of input earthquakes are two important factors that can notablely influence the seismic response characteristics of superstructure.When the input ground motion acceleration amplitude gradually increases from 1 to 4 m/s2,the acceleration of pier top will increase,but it will not be simply proportional to the increase of input acceleration amplitude.

Study of beat phenomenon on a pile-supported pipeline system subjected to wave loading

Classical beat phenomenon has been observed in most combined systems. The focus of this paper is to provide a better understanding of this phenomenon in an offshore pile-supported pipeline system. The beat phenomeon is caused by the coupling movement of the pipeline and its vertical pile support under certain conditions. It can induce excessive vibration and cause fatigue failure at pipe elbow. However, in some circumstances it does not exist. Numerical results in both frequency and time domains are presented to elucidate this phenomenon in a combined pipeline system. The conclusions of this paper could give constructive guidance to future design of simply supported pipeline systems.

Android平台i-Jetty服务器在智能家居中的应用研究

针对智能家居系统架构复杂、开发难度较大等问题,提出了一种基于Android平台嵌入式Web服务器i-Jetty的智能家居系统方案。在ARM硬件平台及Android软件平台上,采用i-Jetty服务器实现了家居环境信息网络远程监控功能。系统以Mini6410开发板为中央控制器、服务器和室内监控平台,采用蓝牙与被控设备进行通信,通过Linux层驱动加载、Android本地服务和Web服务的联合编程,实现对传感器数据的获取、家电控制和信息发布。实验结果证明了方案的可行性和实用性。

海外石化码头项目装卸设施多层布置方案

针对国外石化码头平台相对于国内码头占地面积较大、设施拥挤严重的问题,提出一种新型装卸工艺设施布置方案,即码头结构采用双层设计,上层为日常操作平台,下层为靠泊系缆平台。在此基础上,装卸工艺设施分3层布置,其中需要日常操作的工艺设施布置在上层平台,辅助管道设施及电仪桥架悬挂在首层平台下,残液罐及废水收集池布置在下层平台。以东南亚某化工码头项目为例,介绍该布置方案的运用,并采用BIM技术创建码头装船工艺设施模型,进行装卸臂、登船梯的兼容性分析及相互间操作干涉分析,以提高码头操作可靠性及安全性。设计方案可显著优化装船平台布置,平台占用率降低40%,为运营操作、检修及改扩建提升了空间。同时,BIM技术用于船岸兼容性分析可避免装卸操作潜在的风险。

离岸油码头海底管线测漏系统方案设计及应用

海底油气管线若发生泄漏,会造成财产损失和海洋环境污染,及时发现泄漏并对泄漏情况进行分析和定位,可以减少损失,加强对管线的质量控制。文中研究了离岸油码头项目中海底管线的测漏系统,通过对现有的测漏技术进行比较和分析,提出了离岸油码头项目中海底管线测漏系统的实际应用方案,将负压波法和流量平衡法组合起来使用,能够使泄漏检测精度提高,误报警率降低,为该项目提供了一种可靠、高效的解决方案。

石化码头项目环境影响评价工程分析要点

石化码头项目环境影响评价的基础和关键为工程分析章节,直接影响后续环境影响预测与评价的内容和结论。按照水运工程、海洋工程、石化行业等相关标准和规范,结合石化码头项目施工期和运营期工程特点,通过某新建海港石化码头项目环评报告书工程分析的相关内容剖析,寻找其中可切入的同行业共同点,从而阐明石化码头项目环评报告书工程分析的关注点及评价要点。

Experimental Investigation of Irregular Wave Uplift Force on Deck of Exposed High-Pile Jetties

A laboratory setup was developed to investigate irregular wave uplift loads on exposed high-pile jetties. It is shown that the dimensionless uplift load increases to the maximum with an increasing relative clearance and then decreases. The relative clearance corresponding to the peak force is linked to a range from 0.4 to 0.8. When the relative clearance exceeds a certain value, the wave can not reach the underside of the deck and the force becomes zero. Distinct trends of dimensionless force with a relative width of deck show that the force tends to decrease as the relative deck width increases, and then the decrease slows down after the relative deck width increases or decreases to a certain value. The pressure distribution length associated with the maximum uplift force is equivalent to the wave contact width x. When x is larger than the width of deck B, it is taken as B. The statistical distribution of loads obeys the Weibull distribution. The results from the analyses of the real data suggest a new dimensionless prediction model on wave-in-deck uplift loads and the conversion ratio between wave loads at different exceedance probabilities. A comparison is made between the new prediction model and the existing widely used three prediction models. These results are used as useful references for structural design of the jetty.

Computation of Diffraction of Irregular Waves Behind Double Jetty

The coefficient of deffraction of regular waves behind the double jetty has been computed in this paper at first by using the singularity distribution method. The model tests conducted for diffraction of irregular waves with a unidirectional frequency spectrum have confirmed good agreement between the data measured in experiments and the results computed by the singularity distribution method plus the linear superposition method for the energy of component waves in the directional frequency spectra. Therefore, this technique for component waves in the directional spectra has been further used to compute diffraction of irregular waves of multidirection, including the employment of a directional distribution function of the cos2 type, as well as the Bretschneider-Misuyann frequency spectrum.

Effect of the Twin Jetties as A Regulating Structure at the Tao-er Estuary

The phase one project of the twin jetties at the Tao-er Estuary yields no effect on the flow, and there is a large area of deposition. A numerical model is employed to simulate the flow field, and the scouring and silting in the channel between the two jetties are analyzed. The results show that the effective tidal flux between the two jetties is reduced due to the notch located at the heel of the east jetty, and the effect of contraction-flush is not obvious. As for the regulation of this kind of estuary under the tide action, the capability of tidal flux should be fully used.

Computation of Diffraction of Irregular Waves Behind Single Jetty

This paper presents a calculation method for the diffraction of both regular waves and irregular waves of the single directional frequency spectrum behind a single jetty with a theoretical analysis, which has been confirmed through the model experiments, derives a method of computing the diffracted irregular waves behind the single jetty with the theoretical analysis on the basis of computation of the field data and gives the formulas and the figures of the computation of wave diffractions behind the vertical wall or mound single jetties.

The Behaviour of LNG Carrier Moored to a Jetty Exposed to Waves,Swell,Unsteady Wind and Current

Most terminals for tankers are piers and sea islands, while other types include single point moorings and multiple-buoy moorings. The LNG and LPG carrier moored to the jetty is a very common terminal for transfer of gas in open seas. It is important to estimate the motions and line tensions of the LNG carrier when it moors to a jetty in metocean environment. Normally, the motions of the LNG carrier would be restricted by the loading arm, which is connected to LNG carrier's manifold. An example of 125,000 m(3) LNG carrier moored to a jetty exposed to a set of environment conditions is given. A mathematical model which is based on the equations of motion in the time domain is used to the analysis of LNG moored to an offshore jetty exposed to waves, swell, wind and current. By means of a time domain computer program TERMSIM computations are carried out to determine and optimize the lay-out and / or orientation of the jetty and mooring gear in terms of forces in mooring lines and fenders and the envelope of motions of the loading arms. The purpose of this study is to determine the sensitivity of the mooring system and carrier motions to the combinations of wind waves with and without swell, steady wind and wind spectra. The results can be consulted by the designer in the design of jetties.

Analysis on kinematic and inertial interaction in liquefiable soil-pile-structure dynamic system

The dynamic pile-soil interaction in a liquefied site was investigated by means of numerical simulation and shaking table tests in this study.Based on the results from the shaking table experiment,the cross-correlation analysis of the soil displacement-pile bending moment and superstructure acceleration-pile bending moment was performed to study the influence of kinematic interaction and inertial interaction on the seismic response of piles.A relatively reasonable and accurate finite difference numerical analysis model of liquefiable soil-pile group-superstructure dynamic system was established.Through numerical simulation,the understanding of kinematic interaction and inertial interaction in the shaking table test was verified.The mass,damping and period of the superstructure were selected as variables to carry out parameter analysis to further study the influence of inertial interaction on the pile-structure failure mechanism.The results show that the influence of kinematic interaction on the pile was much greater than that of inertial interaction.The mass of the superstructure was the most important parameter of inertial interaction,and dynamic characteristics of the superstructure also had an effect on inertial interaction.The effect of inertial interaction on the part near the pile tip was more significant,indicating that the failure near the pile tip is closely related to inertial interaction.

深中通道泄洪区非通航孔桥110 m跨钢箱梁转运落梁关键技术

深中通道伶仃洋大桥东、西泄洪区非通航孔桥为110 m跨连续钢箱梁桥,包括6联6×110 m、2联5×110 m,每联钢箱梁由133.1 m长首孔、110 m长中孔和86.1 m长末孔组成,主梁为分幅等截面船形钢箱梁(单箱三室结构,梁顶宽20 m、高4 m),共80片钢箱梁采用中山梁场转运,再由3600 t“天一号”运架一体船架设。钢箱梁在梁厂制造后,通过滚装上船,运输至中山梁场出海码头后,采用“浮托法”转运落梁。钢箱梁在码头通过模块车横向滚装上运输船,运输船上设置2根托梁,钢梁直接落在托梁上;运输船载着托梁和钢梁沿横门东航道行航行至中山梁场出海码头,运输船垂直进入码头中间,当托梁位置到达设计位置后,收紧锚绳,通过调整压载水舱和潮涨潮落,将钢箱梁和托梁落在码头上,完成钢箱梁转运落梁工作。采用浮托法转运落梁转运效率可达1片/d。

长周期波浅覆盖层无掩护海域离岸码头施工关键技术

依托巴基斯坦中电胡布燃煤电厂煤码头工程,针对长周期波浅覆盖层无掩护海域离岸码头施工的特点和难点开展研究,从“长周期波浅覆盖层无掩护条件下离岸高桩码头总体施工方案”、“长周期波浅覆盖层条件下钢栈桥施工方法”、“步履式液压顶推平台法钻孔灌注桩施工方法”、“长周期波及经历季风期外海孤岛防波堤施工技术”共4个方面,运用理论分析、现场实施效果、综合理论研究、科学试验多项手段,解决长周期波浅覆盖层无掩护海域高桩码头施工的技术难题,形成了成套的建设技术,为类似条件外海码头施工积累了宝贵的经验。

浮式天然气发电船码头系泊数值分析

针对发电船在近岸码头设计环境条件,采用挪威船级社(DNV)Sesam软件SIMA模块,对发电船系泊系统进行数值仿真分析,预测系泊缆、靠垫在各种工况下的系泊载荷,并与船级社规范要求进行对比分析,确保发电船系泊系统设计合理性。