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粉土地基下桶形基础沉贯试验研究及工程应用 总被引：2，自引：0，他引：2
桶形基础采用负压沉贯法施工,与压桩、打桩等施工方法显著不同,且阻力特性受地基性质影响很大。介绍了一组粉土地基条件下的模型试验情况,探索了桶形基础的沉贯阻力与负压、渗流等的关系,并与实际平台沉贯过程进行了对比。 相似文献
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进行了桶形基础负压沉贯的室内试验、中间试验和现场沉贯.对负压沉贯的机理进行了初步分析,结合CB20B桶形基础计量平台的现场测试数据,研究了负压对桶形基础沉贯阻力的影响及对土壤特性的影响,同时对负压、沉贯深度、沉贯速度之间的关系进行了总结.在此基础上,提出了改进的计算沉贯阻力的经验公式. 相似文献
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进行了桶形基础负压沉贯的室内试验、中间试验和现场沉贯。对负压沉贯的机理进行了初步分析,结合ＣＢ２０Ｂ桶形基础计量平台的现场测试数据,研究了负压对桶形基础沉贯阻力的影响及土壤特性的影响,同时对负压、沉南深度、沉贯速度之间的关系进行了总结。在此基础上,提出了改进的计算沉贯阻力的经验公式。 相似文献
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介绍了桶形基础负压沉贯的室内试验,中间现场试验,应用有限元法对负压沉贯的渗流场分析,负压对桶形基础沉贯阻力的影响,对土壤特性的影响,负压大小对桶形基础沉深,沉速的影响,研究了桶形基础在海上的可行性。 相似文献
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讨论了浅海桶形基础平台负压沉贯渗流场有限元分析方法。通过模型实验结果与有限元分析结果的对比,验证有限元法的可靠性。将有限元法用于桶形基础平台负压沉贯渗流场的计算,得到沉贯过程中许用负压随插深的变化,用于指导平台就位施工时的负压控制。不同插深时,相应许用负压下的桶内、外壁渗流水头和水头梯度分布的计算结果,用于沉贯阻力的计算。 相似文献
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讨论了浅海桶形基础平台负压沉贯渗流场有限元分析方法.通过模型实验结果与有限元分析结果的对比,验证有限元法的可靠性.将有限元法用于桶形基础平台负压沉贯渗流场的计算,得到沉贯过程中许用负压随插深的变化,用于指导平台就位施工时的负压控制.不同插深时,相应许用负压下的桶内、外壁渗流水头和水头梯度分布的计算结果,用于沉贯阻力的计算. 相似文献
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桶基平台负压沉贯施工机具的研究与应用 总被引：1，自引：0，他引：1
桶形基础采用负压沉贯方法施工,初始入泥和倾斜控制成为制约桶形基础平台应用于浅水区的重要环节。通过分析沉贯、倾斜调整机理,设计了１种负压沉贯施工机具,并成功应用于ＣＢ２０Ｂ桶形基础平台的海上安装,对浅水区桶形基础平台施工机具研究开发具有指导意义。 相似文献
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桶形基础沉贯室内模型试验研究 总被引：3，自引：0，他引：3
桶形基础采用负压沉贯法施工,其贯入阻力与压桩,打桩等施工方法显著不同。本文介绍了在粉土和粉质粘土地层中的一组模型试验情况,认为负压法施工可显著降低粉土的抗贯阻力,但在粉质粘土中减阻效果不明显。 相似文献
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自落式贯入仪(Free-Falling Penetrometer, FFP)是一种新型海底沉积物原位测量设备,用于海底沉积物工程性质原位调查。本文基于自主研发的FFP设备在黄海海域开展现场贯入试验,分析探头尺寸对判断沉积物性质的影响。研究表明,在不同沉积物中探头尺寸对贯入深度、贯入阻力和沉积物类型判断有不同影响。在细粒沉积物中探头尺寸对贯入深度、贯入阻力影响较小;在根据贯入阻力变化划定分层时,小直径探头能反应贯入阻力更为细小的变化。在粗粒沉积物中探头尺寸影响更明显,大尺寸探头使贯入阻力变大,贯入深度减小。根据标准化深度和硬度因子可区分粗粒沉积物和细粒沉积物,在粗粒沉积物中探头尺寸增大,硬度因子减小,有利于细化沉积物类型。 相似文献
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We use flume experiments and numerical modeling to examine the penetration depth of internal solitary waves (ISWs) on partially saturated porous sandy silt and clayey silt seabed. The results of the experiment and model showed that the instantaneous excess pore water pressure in both the sandy silt and clayey silt seabed followed the same trend of decreasing with the seabed depth. In general, the excess pore water pressure generated by the sandy silt was bigger than that by clayey silt at the same depth. The ISW-induced excess pore water pressure greatly influenced the surface seabed and showed a linear relationship. The penetration depth was approximately one order of magnitude smaller than the half-wavelength of the ISWs, which might be larger than the penetration depth induced by surface waves. Our study results are helpful for understanding the damage that ISWs inflict upon the seabed and for informing future field experiments designed to directly measure the interaction between ISWs and seabed sediments. 相似文献
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航船应急抛锚时锚板贯入土体可能会影响河床或海床中的结构物甚者造成破坏，因此在通航频繁的航道，结构物埋深的设计需要充分考虑应急抛锚时锚板的贯入深度。本文通过缩尺模型试验模拟了霍尔锚在中等密实度粉细砂中的抛锚贯入过程，研究了不同抛锚速度(1.15～4.4 m/s)及粉细砂相对密实度(0.45～0.65)对抛锚贯入深度的影响；基于太沙基极限承载力理论和能量守恒定律，推导出霍尔锚在粉细砂土中贯入深度的表达式，与模型试验结果对比显示理论计算结果偏于保守。基于试验结果提出修正系数，修正后的理论公式能够较好地快速预测霍尔锚在中等密实度粉细砂中的贯入深度。研究结果为粉细砂土河床或海床中的结构物埋深设计提供了一定的技术参考。 相似文献
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为了研究黄河口海床沉积物固结过程中电阻率同工程力学性质指标的对应关系,探索海床土体固结过程的新型原位监测技术,本文在黄河刁口流路三角洲叶瓣潮坪上,现场取土配置黄河口快速沉积形成的流体状沉积物和观测研究粉质土海床的固结过程。利用静力触探、十字板剪切试验、孔隙水压力监测等原位土工测试手段,实时测定固结过程中海床土强度变化和孔隙水压力消散过程;同时通过埋置自行研制的环形电极探杆,实时测定海床土固结过程中的电阻率变化。通过对比分析海床土电阻率与工程力学性质指标的同步测定数据发现:黄河口饱和粉土的电阻率与微型贯入试验测得的土体贯入强度,静力触探试验测得的比贯入阻力,十字板剪切试验测得的不排水抗剪强度(峰值强度、残余强度)均呈乘幂关系,且相关性良好;海床沉积物在固结过程中的电阻率与孔隙水压力呈负线性相关性。 相似文献
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This paper conducts laboratory tests to investigate detailedly the soil deformation law around the pipeline and its penetration depth under self-gravity. The seabed model is prepared by consolidating saturated soil using vacuum pressure technology, and the pipeline models are specifically designed to possess different radii. Based on the experimental results and digital images, the soil deformation process is analyzed and summarized, a kinematic admissible velocity field is given and an upper bound solution of pipeline penetration depth and soil reaction force is derived and proposed in this paper. In order to verify the accuracy of the upper bound solution deduced in this paper,a comparison is made among some published results and the solution suggested in this paper, the comparison results confirm that the upper bound solution and the soil failure mode are reasonable. Finally two empirical formulas are given in this paper to estimate the soil reaction force of seabed and the penetration depth of pipeline. The empirical formulas are in agreement with the upper bound solution derived in this paper, and the conclusion of this paper could provide some theoretical reference for the further study of the interaction between the pipeline and the soil. 相似文献
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With the application of innovative anchor concepts and advanced technologies in deepwater moorings, anchor behaviors in the seabed are becoming more complicated and pose a great challenge to the analytical methods. In the present work, a large deformation finite element (FE) analysis employing the coupled Eulerian–Lagrangian technique is performed to simulate the installation/mooring line, and then is applied to analyzing comprehensive anchor behaviors in the seabed. By connecting cylindrical units with each other using connector elements, the installation/mooring line is constructed. With the constructed installation/mooring line, FE simulations are carried out to investigate comprehensive anchor behaviors in the seabed, including long-distance penetration of drag anchors, keying of suction embedded plate anchors and non-catastrophic behavior of gravity-installed anchors. Through comparative studies, the accuracy of the proposed method is well examined. A parametric study is also undertaken to quantify the effects of the frictional coefficient, initial embedment depth, and soil weight on the profile of the embedded anchor line and the shackle load. The present work demonstrates that the proposed FE model, which incorporates the installation/mooring line and the anchor, is effective in analyzing the comprehensive anchor behaviors in the seabed. 相似文献
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Zhuangcai Tian Lei Jia Naili Hu Susheng Wang Mingwei Zhang Guoqing Zhou 《海洋学报(英文版)》2023,42(2):142-149
Internal solitary wave(ISW) is often accompanied by huge energy transport, which will change the pore water pressure in the seabed. Based on the two-dimensional Biot consolidation theory, the excess pore water pressure in seabed was simulated, and the spatiotemporal distribution characteristics of excess pore water pressure was studied. As the parameters of both ISW and seabed can affect the excess pore water pressure, the distribution of pore water pressure showed both dissipation and phase lag... 相似文献
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This paper describes a new device for measuring seabed sliding resistance in situ, and provides an associated interpretation procedure. The device is designed to use a work class ROV as a testing platform to allow measurements to be obtained without use of a specialized geotechnical survey platform. The measurements are to assist pipeline design or analysis of the sliding resistance of other on-bottom infrastructure such as anchor chains. The device has been trialled using three tools: a flat plate, a cylindrical pipe section and a length of chain. The tools are dragged axially along the seabed using the ROV thrusters or a separate hydraulic actuator. An interpretation technique has been developed to estimate the passive resistance mobilized by the faces of the tools to eliminate end effects and to account for shape effects such as wedging. Onshore-trial tests were performed in a bed of dry sand. The individual tools exhibited different overall coefficients of friction, but the back-analysis method yielded equal interface friction angles acting on all three devices, indicating internal consistency. The interface friction angle also matched shear box test results. These outcomes confirm the correct operation of the device in drained seabed conditions, and yield useful information on the sliding resistance of pipes and chains. In addition, the back-analysis method allows measurements from one shape of tool to be used to estimate the response of other objects. 相似文献