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1.
在淤泥质海岸建造高桩码头,通常在开挖基槽后沉桩再抛石形成棱体。基槽中的回淤淤泥很难清除,为此研制了堤下爆炸挤淤新工艺。本文是关于该新工艺的理论、实验及工程应用的一个总结,分两部分,第一部分着重介绍挤淤机理、装药工艺、模型律及药量公式等。研究及应用表明,这种新工艺与先前我们研制成功的爆夯法及爆填法一起,构成了较为完整的工艺系列。  相似文献   

2.
介绍了建筑黄河油港,采用板桩结构码头设计工艺和施工技术,码头建成投产至今,经历了百扯遇强台风考验,为在淤泥质开敞海底建设板桩码头取得了成功经验。  相似文献   

3.
小尺度群桩应用广泛,一直是学者研究的重点,小尺度有别于大尺度桩柱,由于桩柱周围存在漩涡的脱落,使得受力特性复杂。以往的研究过程中,波浪主要采用单向不规则波浪,并且试验模型多以两桩或三桩组成的群桩结构为主,桩数相对较少。多向不规则波与群桩结构的作用特点有别于单向不规则波且研究较少。通过物理模型试验,针对多向不规则波对于9桩桩排群桩结构的作用进行了研究。首先综合考虑KC1/3数和相对桩径的影响,提出以参数KCLD 1/3数来衡量群桩的效应,并分析了正向力与横向力随着参数KCLD 1/3数和相对桩距的变化关系,研究了群桩中不同桩位桩柱波浪力的变化规律和方向分布宽度对于群桩波浪力的影响。研究结果表明,群桩中各桩的正向力随着方向分布标准差的增大而减小,而横向力在相对桩距较大时随着方向分布标准差的增大而增大,同时群桩中不同位置桩上的波浪力具有较大的差异。  相似文献   

4.
在开敞海域,淤泥底质建造板桩结构码头的实践与分析   总被引:1,自引:0,他引:1  
本文主要以黄河海港建港的经验与实践,介绍板桩结构码头的设计特性和施工过程的技术措施,提供了在开敞海域下淤泥底质建港的实践经验和应用前景。  相似文献   

5.
螺旋桩芯劲性复合桩(helix stiffened cement mixing pile,简称HSCM桩)是一种新型复合桩,其成桩工艺会对桩身及其承载性能有较大影响。为验证HSCM桩在软黏土中同步旋进注浆工艺的可行性,并研究其成桩参数对抗压承载性能的影响,设计了2组缩尺模型试验,包括不同叶片数量与钻进速度的HSCM桩与对比螺旋桩。通过在高岭土制备的软黏土中成桩,并进行抗压承载性能及桩身几何尺寸测试,分析HSCM桩的成桩参数与水泥土桩身间的关系。试验结果表明:同步旋进注浆工艺能够在螺旋桩周围形成倒圆台状的水泥土桩身,水泥土桩身的平均黏结直径约为叶片直径的1.17~1.35倍;适当增加叶片数量能够使水泥与土体充分拌和,提高水泥土桩身的完整性与连续性,以改善HSCM桩的成桩质量;钻进速度大幅提高会导致注浆量不足,减小水泥土桩身的黏结直径与刚度;试验条件下HSCM桩的抗压极限承载力是螺旋桩的3.83~3.93倍,桩径扩大提高了侧摩阻力,注浆工艺加固并提高了土体强度,弥补了叶片在旋进过程中扰动土体造成强度降低的问题。  相似文献   

6.
钢管斜桩是潮间带风电的常用基础形式,常采用吊打沉桩的方式。文章针对潮间带吊打沉桩方式的难点开发吊打导向装置,并总结沉桩参数的确定方法。该导向装置包括定位桩、定位架和调向限位架,总体平面布局为六边形,可一次定位并完成整个风电基础的基桩施工,既能可靠保证桩的施工精度,又能极大地提高施工效率和降低安全风险;在应用该施工关键装备时,采用GRLWEAP打桩分析功能确定桩顶动荷载,采用有限元软件建立导向装置有限元模型,对导向装置和沉桩参数进行分析,从而实现斜桩顺利沉桩的目的。该装置和方法已成功应用于越南朔庄一期海上风电场项目,为潮间带风电钢管斜桩吊打施工提供沉桩装备和方法经验。  相似文献   

7.
海洋桩平台采用大直径超长桩,由于桩、锤的重量很大,沉桩过程中经常发生溜桩现象。因此为了便于打桩控制,判断溜桩的范围是非常必要的。结合实际工程对溜桩的过程和发生机理进行了探讨;利用PCPT原位测量资料,基于能量法建立了判断溜桩范围的分析计算方法。针对南海油田典型的平台桩沉桩过程中的溜桩问题进行了分析计算,验证了所提出的方法的合理性,可供桩设计以及沉桩施工参考。  相似文献   

8.
考虑群桩效应的海洋平台桩—土—结构共同工作研究   总被引:1,自引:0,他引:1  
考虑群桩效应的近海导管架平台的桩、土结构共同工作研究是一个很复杂的课题,要考虑很多因素。在平台结构的概念设计或初步设计中则可采用一些近似方法。本文根据目前国内外对群桩研究的成果,依据文克尔相互作用模型,提出了一个较方便实用的群桩效应计算方法,并建立了考虑群桩效应的桩—土—结构共同工作的计算模型,通过编制计算机程序得到实现,最后根据算例分析得到有关结论  相似文献   

9.
基于P-Y曲线法考虑桩土相互作用的高桩结构物分析   总被引:12,自引:0,他引:12  
PY曲线法是一种非线性地基反力法,可用于分析横向荷载作用下桩结构物,尤其在分析有较大变位的桩结构物时,有许多突出的优点。本文就PY曲线法分析横向力作用下的高桩结构物的实施方法、特点进行了研究,编制了相应的程序,结合算例给出一些供工程设计人员参考的结论。  相似文献   

10.
考虑桩土作用独桩海洋平台横向振动特性研究   总被引:5,自引:0,他引:5  
采用动Winkler弹性地基梁模型模拟桩土问动力相互作用,并考虑了流体与桩问相互作用,通过组合成层土中、水中桩单元的刚度阵,推得了独桩海洋平台连续系统横向振动的动刚度阵及在波浪力作用下平台甲板处的频率响应函数,进而求得了在确定性波浪力及随机波浪力作用下桩身任意点的位移响应。最后,通过算例研究和分析了在随机波浪力作用下成层土参数、甲板上重量及冲刷淘深等因素对平台振动响应的影响。  相似文献   

11.
The self-supported earth-retaining structure using stabilizing piles (SSR is used from here) has the advantages of less deformation and less internal force compared with conventional cantilever retaining structure. It is easier to conduct the excavation when SSR is used for an excavation instead of using braced excavation with struts. The SSR is better than other methods to the 10 m shallow excavation depth in terms of economical and constructional efficiency when the ground is not very soft. However, this SSR method lacks a theoretical basis in terms of geotechnical engineering. The objective of this study is to develop a method of analysis by laboratory model tests. A variety of model tests were performed in order to analyze the behavior of SSR and the ground, and to measure the stress acting on stabilizing piles relative to excavation steps and earth pressures on the wall. The analysis reveals the failure mechanism of a wedge and then suggests a method for calculating a virtual supported point. These findings were incorporated into a method for analyzing retaining wall, stabilizing piles, and beams connecting two structures. Future research is geared toward developing a design program that uses the analytical methodology for this SSR.  相似文献   

12.
Abstract

Pipes buried in soft ground can be damaged due to the vertical and lateral movement of the ground during the construction of the embankment. To investigate such a movement of the soft ground, full-scale tests using embankment piles and stabilizing piles were conducted for 70?days. A pile-supported embankment has been used to reduce the deformation of soft ground by transferring the embankment load through piles to the firm layer below the soft ground, whereas stabilizing piles have been employed to resist the lateral earth pressure that is induced in soft ground by embankment loads. The Coupling Area (CA), which was defined as the quantitative index to determine the resistance effect of both settlement and lateral flow of the soft ground when the embankment was reinforced, is adapted. The analysis results of the CA indicate that the piled embankment was more effective for preventing the damage to buried pipe installed near the embankment, while the stabilizing piles had almost the same effect as the piled embankment when the pipe was buried far away from the embankment.  相似文献   

13.
Abstract

In this article, the degradation of the lateral bearing capacity of piles in soft clay subjected to cyclic lateral loading is studied numerically. A modified kinematic hardening constitutive model is employed to simulate the degradation of soft clay after cyclic loading. The modified model is verified by comparing the numerical simulation results with the results of centrifuge model tests. Furthermore, the modified model is applied to numerical simulations for evaluating the lateral bearing capacity of piles in soft clay subjected to cyclic lateral loading. The degradation of the lateral bearing capacity of piles in soft clay after different cyclic displacement levels and different numbers of cycles is investigated. The study reveals that the modified kinematic hardening constitutive model can effectively estimate the cyclic degradation behavior of piles in soft clay subjected to cyclic lateral loading. The degradation of the ultimate lateral bearing capacity progresses slowly with increasing cyclic displacement level for fewer cycles, and the degradation develops significantly at higher levels of cyclic displacement after applying a larger number of cycles.  相似文献   

14.
Erective Sea Embankment with PCC Piles   总被引:2,自引:0,他引:2  
  相似文献   

15.
本文介绍了码头钢管桩潮差段底漆、底胶、聚乙烯包覆三层防腐结构的施工工艺及防腐材料的性能指标并简要介绍了防腐钢管桩的使用情况。  相似文献   

16.
Abstract

Land reclamation has increased significantly in the eastern coastal areas of China. The increased exploitation of offshore resources has made cast-in-situ piles more preferable in these regions. However, precise prediction of axial forces and shaft resistances of piles is particularly difficult because geological conditions are complex after the foundation is treated by vacuum preloading. In this study, two groups of cast-in-situ piles, each of which consisted of two piles installed in soft soil in Oufei Project, Wenzhou, China, were compared by conducting tests using the slow static loading method to evaluate the influence of applying vacuum preloading to deal with soft soil foundation on the vertical bearing capacities of the piles. Two piles were located in an untreated area, while the other two were located in a vacuum preloading treating area. All the piles had the same length and diameter. In addition, the axial forces and shaft resistances of piles were calculated based on the measured strains. The field tests revealed that the ultimate bearing capacities and shaft resistances of test piles were significantly improved compared to those of the piles in untreated area. The experimental results presented in this study are expected to be highly beneficial for practical engineering.  相似文献   

17.
Abstract

Open‐pipe piles are widely used for offshore structures. During the initial stage of installation, soil enters the pile at a rate equal to the pile penetration. As penetration continues, the inner soil cylinder may develop sufficient frictional resistance to prevent further soil intrusion, causing the pile to become plugged. The open‐ended pile then assumes the penetration characteristics of a closed‐ended pile. The mode of pile penetration significantly alters the soil‐pile interaction during and after installation. This affects the ultimate static bearing capacity (mainly in granular materials), the time‐dependent pile capacity (in clays), and the dynamic behavior and analysis of the piles.

Following a summary demonstrating the effects of pile plugging, a review of the common view of offshore pile plugging is undertaken. The interpretation of plugging by referring to the average plug length has led to the erroneous conclusion that in most piles significant plugging action does not occur.

Establishment of an analogy between soil samplers and open‐ended piles enabled correct identification of plugging by referring to the incremental changes in plug length. Examination of case histories of plugging of offshore piles revealed that beyond a certain penetration depth‐to‐diameter ratio, most piles are plugged.  相似文献   

18.
Abstract

In onshore and offshore fields of ocean engineering, piles are used as foundation systems for various structures. Piles are classified into different types depending on their materials, geometries, and particularly, installation methods, which have advantages or limitations. Companies and engineers have developed a new group of piles, because of necessity to improve their performance in terms of increasing the bearing capacity, reducing impacts of traditional installation procedures, implementing by low- torque power equipment, and utilizing them in widely different ground conditions, including in a marine environment. In the present study, three different models of a new pile with an expander body are introduced to increase the shaft and pile-toe diameters and its self-expansion in the embedment depth under the titles of the Bubble pile (BP), Self-Expanded pile (SEP) and Wing pile (WP). The main subject of this research is to achieve increased bearing capacity, reduced installation effects, and decreased required installation torque. The frustum-confining vessel of Amirkabir University of Technology (FCV-AUT) was employed for this purpose. Up to 14 axial compressive and tensile load tests were carried out on different model piles on sand collected from Anzali shore located on the northern coast of Caspian Sea in Iran, with relative densities of 45% to 50% within FCV-AUT. Comparing the performance of introduced pile with traditional pile corresponding to the same characteristics, the results indicated a significant increase in the axial bearing capacity and reduced disturbance effect of the pile. Also, a lower installation torque of the SE pile was required compared to the helical pile. The test results also demonstrated that the new pile could resist considerable compressive and uplift loads, and could be a possible alternative to traditional piles in the onshore sector.  相似文献   

19.
Abstract

This article discusses a possible alternate foundation system for a tension leg platform (TLP) in deep water. It was developed through Tecnomare S.p.A. for Agip S.p.A. during a feasibility study of a site located in the southern Adriatic Sea having a water depth of 827 m. The system is a combination of a pile‐gravity foundation, with relatively short (?20 m) steel piles of very large diameter (6 to 12 m) called “superpiles,”; which are closed at the top and open at the bottom. The superpiles are installed in soft soil under the effect of self‐weight and active suction. Permanent tension of the TLP tendons is equilibrated by self‐weight only; tension due to wave action is equilibrated by the weight of the soil inside the superpiles. In fact, a pulsating tension applied to the superpiles generates a suction in the pore water that tends to keep the soil plug inside the cylinder and prevents the cylinder as a whole from being extracted from the (impervious) foundation soil.

The results of analyses of the installation and in service behavior of superpiles are described on conventional principles of soil mechanics and related to a typical profile at the Adriatic site. Installation problems are briefly discussed; then the stability in service is examined to evaluate the capacity of superpiles in compression and tension and the associated factors of safety. Finally, considering the pore pressure gradient generated by the applied tension inside the soil plug, the flow rate and related deformations during storms and during the entire expected life of the TLP are evaluated.

The proposed superpile system appears to be feasible, simple to install, and economical. Further study and experimental research are justified to optimize the system.  相似文献   

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