共查询到20条相似文献，搜索用时 21 毫秒
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大直径宽浅式筒型基础,阻水宽度大,在位工作期间受波浪海流作用,其周围土体易被冲刷。为研究单侧地基土体受冲刷后筒型基础的竖向极限承载力变化,通过引进冲刷率的概念,采用有限元方法研究了不同冲刷率下筒型基础的竖向极限承载力;并基于Meyerhof理论建立了计算不同冲刷率下筒型基础竖向极限承载力的极限平衡方法。研究结果表明,随着冲刷率增大,筒型基础的极限承载力出现不同程度的下降,当冲刷率为0.8时,即筒型基础单侧土体冲刷深度达6.4 m时,筒型基础的竖向极限承载力折减率为3.28%。建立的极限平衡算法可准确计算冲刷条件下筒型基础的竖向极限承载力。 相似文献
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针对海上风电负压桶型基础,以提高桶基水平承载性能和降低结构动力响应为目的,提出了一种加装稳定翼的负压桶型基础型式。通过在桶身设置一组稳定翼,使得桶周土抗力得以充分利用。以单立柱负压桶基为例,建立桶土全实体有限元模型,进行了静力分析和包括模态分析、瞬态分析、谱分析在内的动力分析。结果表明:稳定翼的设置增强了桶基水平承载性能;水平位移和动力响应显著减小;结构低阶固有频率略有提高。 相似文献
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海上平台桶基沉贯渗流场的有限元法数值模拟 总被引：3，自引：1，他引：2
桶形基础平台是一种新型的海洋平台,这种型式的平台与传统的导管架式平台的主要区别在于采用桶形基础代替打下桩基础,桶形基础的负压沉贯过程是一个复杂的水动力过程,其关键在于主动脉施加的桶内外压力差产生渗流场,渗流场的形成与发展对于负压沉贯有决定性的影响。本文用有限元分析方法对桶形基础负压沉贯流流场进行动态模拟,建立了桶形基础负压沉贯过程中渗流场的有限元分析模型,模型试验的结果与按有限元分析计算模型得一的 相似文献
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Xiaowei Tang Xiwen Zhang Qi Shao Zhenqing Li 《Marine Georesources & Geotechnology》2016,34(6):594-601
In the last 20 years, the bucket foundation has been developed as a new type of offshore platform structure. Because of its short period of application to engineering practices, the theoretical decision on the rotation center and horizontal bearing capacity of the bucket foundation has yet to be agreed. A limit analysis method is used to determine the updated rotation center position and horizontal bearing capacity to evaluate the failure mechanisms of the bucket foundations. The results are compared with numerical simulation and experiments, and also with other theoretical methods. The proposed method can satisfactorily consider the engineering conditions and the result is accurate in determining the rotation center and horizontal bearing capacity. 相似文献
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Calculation of Hydro-Dynamic Stability of the Soil Inside Bucket in the Process of Bucket Foundation Penetration 总被引：1，自引：0，他引：1
—The offshore platform with bucket foundations is a new type of offshore platform that distin-guishes from traditional template platforms by replacing driven piles with bucket foundations.The suctionpenentration of bucket foundation is a complicated hydro-dynamic process.The key of this process is theseepage field caused by the difference of pressure applied on purpose inside and outside the bucket.The ap-pearance and developement of seepage field has a decisive influence on the suction penetration process.Inthis study,the finite element analysis method is applied to the dynamic simulation of the seepage field ofsuction penetration of bucket foundation.A criterion is suggested to distinguish the hydro-dynamic stabili-ty of the soil inside the bucket according to the critical hydraulic gradient method.The reliability of themodel and its applicability to engineering practice have been proved through comparison between the re-sults of model test and finite element calculation. 相似文献
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复合加载下桶形基础循环承载性能数值分析 总被引：1，自引：0，他引：1
作为一种新型基础形式,吸力式桶形基础除了承受海洋平台结构及自身重量等竖向荷载的长期作用之外,往往还遭受波浪等所产生的水平荷载及其力矩等其它荷载分量的瞬时或循环作用。对复合加载模式下软土地基中桶形基础及其结构的循环承载性能尚缺乏合理的分析与计算方法。应用Andersen等对重力式平台基础及地基所建议的分析方法,基于软黏土的循环强度概念,在大型通用有限元分析软件ABAQUS平台上,通过二次开发,将软土的循环强度与Mises屈服准则结合,针对吸力式桶形基础,基于拟静力分析建立了复合加载模式下循环承载性能的计算模型,并与复合加载作用下极限承载性能进行了对比。由此表明,与极限承载力相比,桶形基础的循环承载力显著降低。 相似文献
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用于海洋平台的吸力式桩桶基础作为一种新型平台基础正逐渐成为人们研究的重点。为研究吸力式桩桶单桩基础的受力特性,对V-H（竖向—水平）联合荷载作用下的吸力式单桩基础桩土的承载特性进行了数值模拟,并将数值模拟的有限元解通过与API规范中对p-y曲线的计算方法进行对比来验证有限元模型的可行性,最后采用分级作用力的加载方式对其破坏包络曲线进行绘制,并推导出相应的函数表达式。研究表明,采用ABAQUS有限元分析软件对吸力式桩桶进行数值模拟是可行的,随着对吸力式桩桶所施加V-H联合荷载的不断增大,吸力式桩桶所能体现的应力和弯矩极限值也在随之增大,其位移变化主要在施加荷载的区域附近,最后在联合荷载作用下所体现的极限承载状态,即包络曲线大致呈四分之一的椭圆形状。 相似文献
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Suction buckets are a promising foundation solution for offshore wind energy systems. The bearing behavior of monopod buckets under drained monotonic loading in very dense and medium dense sand is investigated in this study by means of numerical simulation with the finite element method. Special focus is given to the ultimate capacity and the initial stiffness of the bucket-soil foundation system. The numerical model is validated by comparison with field test results. The bearing behavior of the structure is explained through an evaluation of a reference system. It is shown that the bucket experiences a heave during horizontal loading, which leads to the formation of a gap between the bucket lid and the soil with increasing load. At large loads and rotations close to failure of the system there is no contact between lid and soil, and the whole load is transferred to the soil via the bucket skirt. A parametric study shows how the ultimate capacity and initial stiffness of the system depend on the bucket dimensions and loading conditions, i.e. load eccentricity. Normalized equations for ultimate capacity and initial stiffness are derived from the numerical simulation results, which can be used in the scope of a preliminary design for buckets in sand. 相似文献
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桩-筒组合基础是将单桩基础与筒型基础组合的一种新型海上风电基础形式,其受力模式不同于传统桩基基础,优点是可通过合理减小桩长、桩壁厚等途径提高承载性能。基于极限地基反力法,提出单层黏土中桩-筒组合基础受力模式及水平承载力的计算方法。利用力加载和位移加载两种控制方法进行数值分析,研究水平承载性能的影响因素。结果表明,在一定范围内,桩-筒组合基础水平承载性能随桩入土深度、桩壁厚、筒外径的增大而提高。基于实际工程,对等用钢量的单桩基础与组合基础进行比较计算,结果表明,桩-筒组合基础可有效降低基础倾斜度和位移,提高承载性能。 相似文献
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在一个大型土池中进行了软土中组合四桶基础在竖向静荷载与水平循环荷载共同作用下的承载力模型试验,研究了竖向静荷载与水平循环荷载对组合桶形基础破坏形式与承载力的影响。试验结果表明,组合四桶基础的变形主要包括水平循环变形与竖向循环累积沉降。基础的破坏形式取决于水平循环荷载与竖向静荷载。若竖向静荷载较小,过大的水平循环位移将导致基础破坏;随竖向静荷载增加,竖向循环累积沉降将变为导致基础破坏的主要原因。试验结果还表明,在不同竖向静荷载与水平循环荷载共同作用下,基础的水平循环承载力大约为水平静承载力的70%左右。 相似文献
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Existing tripod suction bucket foundations, utilised for offshore wind turbines, are required to resist significant lateral loads and overturning moments generated by wind and currents. This paper presents an innovative type of tripod bucket foundation, ‘hybrid tripod bucket foundation’, for foundations of offshore wind turbines, which has the ability to provide a larger overturning capacity compared with conventional tripod buckets. The proposed foundation consists of a conventional tripod bucket combined with three large circular mats attached to each bucket. A series of experiments were conducted on small-scale models of the proposed foundation subjected to overturning moment under 1g conditions in loose sand. Different circular mat diameter sizes with various bucket spacings were considered and the results were compared with conventional tripod bucket foundation. Finite element models of the proposed foundation were developed and validated using experimental results and were used to conduct a parametric study to understand the behaviour of the hybrid tripod bucket foundation. The results showed that there is a significant increase in overturning capacity provided by the novel foundation. The results of this work can significantly improve lowering the costs associated with installation of foundations to support offshore wind turbines. 相似文献
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近海海床表层多为软黏土或淤泥质土,为探究海床表层软土对海上风电宽浅式筒型基础承载特性的影响,以中国广东某海域风电场为背景,通过有限元分析的方法,研究竖向、水平、弯矩荷载作用下软土层厚度和土体强度对基础极限承载力、破坏模式以及筒基土压力分布的影响。研究结果表明:当软土层厚度小于H/2(H为筒裙高度)时,单向荷载作用下宽浅式筒型基础极限承载力随软土层厚度的增加呈线性减小的趋势;当软土层厚度大于H/2后,承载力降低速率逐渐增大。表层软土的存在,使得塑性区范围缩小,软土层内土体塑性破坏更加明显。竖向荷载作用下,随软土层厚度的增大,筒顶承载先减小后增大,筒内侧摩阻力先增大后减小;水平荷载和弯矩作用下,筒侧被动土压力的降低是引起软土覆盖地基中基础承载能力降低的主要因素。 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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A shallow suction bucket is a new foundation type for offshore wind turbines. Due to its large size and bulky shape, the bucket and the soil within the bucket do not necessarily deform as a whole. Moreover, limited research has been conducted on the hydrodynamic wave influence on the shallow bucket bearing response. These factors pose great challenges to the shallow bucket foundation design. This paper presents a set of centrifuge tests of a shallow bucket model subjected to monotonic and dynamic lateral loads to study the lateral bearing response of shallow bucket foundations in the field under combined loads induced by wind, waves, etc. In addition to the routine measurements (e.g., load-displacement), the soil pressures on the bucket and the distribution and evolution of the excess pore pressures in the surrounding soils are also obtained. The deformation pattern of the bucket (e.g., rotation center) is revealed through displacement measurements. Finally, the proposed easy-to-use analytical equations using the limit equilibrium to assess the bearing capacity of bucket foundations, taking into account the influence of the soil strength degradation caused by hydrodynamic wave loadings, are found to yield good results upon comparison with the centrifuge data, providing useful guidelines for the design of shallow bucket foundations. 相似文献
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As an appropriate type of foundation for offshore wind turbines (OWTs), wide-shallow composite bucket foundation (WSCBF) is cost-competitive, and it has a unique and special substructure that comprises seven internal rooms arranged in a honeycomb-like structure. In this study, the cyclic behavior of WSCBF for OWTs embedded in saturated clay was investigated using a large-scale model subjected to lateral cyclic loading. The responses of foundation under constant- and various-amplitude cyclic loadings were recorded in terms of displacements, rotations, and bending moments. The variations in stiffness and damping were obtained, and a collaborative bearing mechanical model between the bucket and soil was considered, which was beneficial for improving the stiffness of the whole structure. Accumulative deformation was found to have little effect on the bearing capacity of the foundation. Dynamic analysis in frequency domain was further performed on both moment and rotation data, and the complex, frequency-dependent impedance was also studied. 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