共查询到20条相似文献，搜索用时 618 毫秒
1.
海上风力发电作为一种绿色能源越来越受到重视,单桩基础局部冲刷的研究受到广泛关注。建立了不同冲刷深度的海上风机系统模型,对各模型进行静力、动力分析。结果与前人冲刷模型试验吻合,随着桩基冲刷深度的增大,支撑系统的最大水平位移、最大水平应力和最大弯矩值逐渐增加。冲刷深度为两倍桩径时,最大水平位移、应力及弯矩分别比无冲刷条件下增加了3.61%、12.7%、10.3%。风机系统的自振频率随冲刷深度的增加而降低,高阶频率更易受影响。桩基冲刷对风机系统的动力特性有显著影响,塔顶水平位移时程曲线随冲刷深度不断上移。海上风机设计时必须考虑冲刷对支撑系统承载性能的影响。 相似文献
2.
为探讨海上风机在风、浪等水平往复循环荷载下大直径单桩基础的循环弱化特性,设计了稳定输出长期循环荷载的机械加载装置,开展了软黏土中长期水平循环荷载下海上风电大直径单桩基础和传统长桩基础的模型试验对比研究。根据API给出的骨干曲线和Masing二倍准则构建循环荷载下的p-y（荷载-位移）曲线,并借鉴前人工作,采用累积塑性应变描述软黏土的不排水抗剪强度弱化,提出了分析大周数水平循环荷载下单桩基础循环弱化的理论方法。该方法将循环荷载次数、幅值等外界条件与桩周土体的循环弱化特性建立联系,以适应海洋环境复杂多变的水平循环荷载形式。通过模型试验和理论研究认为,大直径单桩基础因刚度较大,在同样的水平力循环荷载条件下,其抵抗循环荷载的能力明显优于传统长桩。在海上风机大直径单桩的设计中采用基于黏土残余强度的循环后稳定水平承载力更为合理。 相似文献
3.
Acta Geotechnica - Large diameter, short monopiles are the preferred foundation type for offshore wind turbines. These piles demonstrate a rigid response with significant rotation of the pile base... 相似文献
4.
Xiangshui offshore wind power station is located in shore water near Chengang of Jiangsu province. As the pile groups of the wind turbines have complicated engineering characteristics, their design is one of the technical difficulties of the project. Deformation behaviors of the piles foundation of Xiangshui 2MW wind turbine generator system are computed and analyzed under static loads and cyclic wind loads. The results show that deformations of the foundation are allowable; and the deformations due to static loads are comparatively smaller than that under the containing cyclic wind loads condition. With the depth increasing, the horizontal displacement and its influence range decrease; while the maximal vertical settlement is steady and vertical influence range increases. Deformation characteristics of pile-soil system depend not only on the loads combination of the subject, but also on the soil conditions. 相似文献
5.
7.
吸力基础具有施工方便、可回收利用及造价低等优点，在海洋平台及海上风电工程中得到了成功应用。吸力基础用于系泊深海浮动式平台时，抗拔承载特性是工程设计的重要因素。海上风电场面临着服役期满后的升级改造问题，需采用更大功率的发电设备，风机叶片直径、塔架高度随之增加，原基础难以满足新的设计要求，从可持续发展角度，塔架基础的拔出、回收等方面正逐渐引起人们的高度重视。本文介绍了吸力基础抗拔、拔出特性方面取得的研究成果，阐述了影响基础抗拔和拔出特性的因素，阐明了吸力基础拔出的力学机制与作用机理。通过文献调研推断:注水拔出吸力基础，砂土会发生渗流破坏，黏土会产生劈裂破坏，会导致基础无法继续上拔，应结合拉力上拔或振动法对基础进行回收。 相似文献
8.
The fatigue life of offshore wind turbines strongly depends on the dynamic behaviour of the structures including the underlying soil. To diminish dynamic amplification and avoid resonance, the eigenfrequency related to the lowest eigenmode of the wind turbine should not coalesce with excitation frequencies related to strong wind, wave and ice loading. Typically, lateral response of monopile foundations is analysed using a beam on a nonlinear Winkler foundation model with soil–pile interaction recommended by the design regulations. However, as it will be shown in this paper, the guideline approaches consequently underestimate the eigenfrequency compared to full-scale measurements. This discrepancy leads the authors to investigate the influence of pore water pressure by utilising a numerical approach and consider the soil medium as a two-phase system consisting of a solid skeleton and a single pore fluid. In the paper, free vibration tests are analysed to evaluate the eigenfrequencies of offshore monopile wind turbine foundations. Since the stiffness of foundation and subsoil strongly affects the modal parameters, the stiffness of saturated soil due to pore water flow generated by cyclic motion of monopiles is investigated using the concept of a Kelvin model. It is found that the permeability of the subsoil has strong influence on the stiffness of the wind turbine that may to some extent explain deviations between experimental and computational eigenfrequencies. 相似文献
9.
复合筒型风电基础单向流局部冲刷试验研究 总被引：1，自引：0，他引：1
复合筒型基础是一种新型的宽浅式海上风电基础,相对于桩基础等深基础,复合筒型基础周围地基的冲刷破坏对风机结构体系安全性的影响更加明显,因此,研究海流作用下复合筒型基础的冲刷特性很有必要。针对某工程实例,建设了冲刷试验场地,布置了典型测点,为复合筒型基础冲刷试验奠定了基础;采用系列比尺模型的方法,分别选取1:20、1:40、1:70三种比尺的模型,对海上风电复合筒型基础样机周围粉砂质海床的冲刷情况进行了试验研究;分析了各组试验冲刷平衡时间、模型周围冲刷坑的范围、最大冲刷深度,并且依据系列比尺模型试验原理计算出了实际工程中的冲刷深度。通过试验研究给出了实际工程复合筒型基础的最大冲刷深度,明确了单向流作用下复合筒型基础周围地基局部冲刷特性,填补了复合筒型基础冲刷试验研究的空白,为复合筒型基础的工程应用提供了指导。 相似文献
10.
水平循环荷载下风电机桩基础离心模型试验研究 总被引：4，自引：0，他引：4
在近海风力发电工程中桩基是常用的基础型式,海上风力发电机桩基础一般建立于复杂软土地基、承受着海上风浪、潮流等近似水平向的循环荷载作用,而风力发电机组运行对基础的承载力和变形有严格的要求。因此,研究水平循环荷载下桩土系统变形规律和相互作用机制具有重要的意义。针对典型的近海风机单桩基础,选取典型的饱和砂性土地基,通过离心模型试验的方法研究了水平循环荷载下的风机桩基础的受力变形规律。试验结果表明,水平向循环作用下,桩周围土体中变形主要呈现为挤压或塌陷产生的沉降和水平向变形,变形主要集中在桩周围较小的范围内;变形呈现逐渐累积特性,其大小随着循环次数的增加而增加;桩身弯矩峰值出现在埋深上1/3处,多次循环后的弯矩大小和分布变化不大;桩周围土体中不同位置产生不同的超静孔隙水压力,孔隙水压力发展对土体变形有一定影响 相似文献
11.
桩基础是近海风机经常采用的基础形式。由于风电机组对基础的承载力和变形有着严格的要求,而水平荷载常常是控制荷载,因此,研究水平荷载作用下风机桩基础的应力、变形特性具有重要意义。针对风机单桩基础,选取典型的黏土地基,进行了水平加载条件下的离心模型试验,重点分析了桩身的响应及桩周围土体的变形特点。试验结果表明,在水平荷载作用下,桩顶的水平位移随着水平力的增加而增加,位移的增加速率在临界荷载之后增长较快;桩身弯矩分别在埋深1/5和3/5处附近分别出现极大值和极小值,且桩底具有一定弯矩值;桩周围土体的变形随着离桩距离的增加而减小,可分为主动区和被动区。桩对土体变形的影响区域随着水平力的增加而不断扩展,最后基本稳定在2倍桩径范围内。 相似文献
12.
In this paper we investigate the effect of pile group geometry and loading direction on the ultimate lateral soil resistance developing on a tripod foundation, using numerical and analytical upper bound methods. Two distinct kinematic mechanisms are established, corresponding to different failure modes associated with wide and narrow pile spacing. A comparison of tripod group performance against other common pile group layouts suggests that the former results in optimal efficiency for cases when the direction of the lateral load is unknown, such as the foundation of offshore structures subjected to wind, wave and ocean current loads. 相似文献
13.
海上风电机组筒型基础工作及承载特性研究 总被引：1，自引：0，他引：1
筒型基础是一种新型的海上风电基础,由于其具有减少工程量、节省投资、缩短施工时间、可重复使用等优点,在某些领域正在逐步替代桩基和重力式基础。目前工程上对筒型基础的设计还没有现成的规范可供使用,一般是将筒内部土体与筒壁视为一体,然后采用简化的极限平衡方法进行设计计算,不能反映筒内土体的工作特性。以福建近海某风电基础工程为依托,采用大型有限元软件ABAQUS对海上风机单筒基础的承载特性进行了三维有限元数值分析。根据海上风机的受力特点,考虑基础隔舱的作用效果,建立了筒型基础的简化模型与有无隔舱的计算模型。计算结果表明：筒型基础在受荷过程中,基础内部土体产生屈服变形,使得筒型基础的承载特性不同于简化极限平衡方法。两者之间的差异使得实际的地基承载能力比极限平衡方法计算所得的要小。此外,对现行简化计算方法的误差进行了估计,并对筒型基础承载力计算提出建议,可供筒型基础设计者参考。 相似文献
14.
针对东海大桥近海风电场钢管桩高桩基础的相关工程参数开展了试验研究。通过水平静载荷现场试验测得了海上钢管直桩及斜桩的水平承载力,并采用自平衡测试法测得了桩基的竖向承载力。对波流力作用下连接及未连接平台的钢管桩进行了测试,获得了加速度时程曲线以及钢管桩固有频率。试验结果分析显示,正斜桩的水平承载性能优于直桩和反斜桩;钢管桩未连接平台时,在波流作用下的位移明显大于连接平台后;钢管桩的实测固有频率在1.05～1.3 Hz之间,斜桩的固有频率略高于直桩。试验结果已直接应用于该工程高桩基础设计中。 相似文献
15.
16.
Behavior of monopile foundations under cyclic lateral load 总被引：1，自引：0，他引：1
This paper describes the development and application of design charts for monopile foundations of offshore wind turbines in sandy soil under long-term cyclic lateral load. It outlines a numerical model, working with a numerical concept, which makes the calculation of accumulated displacements based on cyclic triaxial test results possible, and it describes important factors affecting the deformation response of a monopile to cyclic lateral loads. The effects of pile length, diameter and loading state on the accumulation rate of lateral deformation are presented and design charts are given, in which a normalized ultimate lateral resistance of a pile is used. For monopiles with very large diameter, the suitability of the “zero-toe-kick” and “vertical tangent” design critera for determining the required embedded length is discussed. 相似文献
17.
18.
长短桩技术在有邻近堆土建筑中的应用 总被引：1，自引：0，他引：1
建筑物周边的不均匀堆土给建筑物带来了安全隐患,如何消除这些安全隐患又避免高昂的桩基工程造价,就这一问题针对土层中存在多层可利用的桩端持力层提出了短桩、桩间土提供承载力,堆土侧采用长桩控制建筑物的不均匀沉降的长短桩组合桩基础的设计思路,并对全短桩方案和邻近堆土侧加长桩长的长短桩方案分别进行了三维有限元分析。分析结果表明,对有邻近不均匀堆土的建筑物采用长短桩组合桩基础,不仅可以有效地控制建筑物的不均匀沉降,而且大大减小了桩基础的工程造价,对解决不均匀堆土对建筑物带来的危害,提供了一种设计思路。 相似文献
19.
Jinbo Chen Robert B. Gilbert Yoo Sang Choo Peter W. Marshall James D. Murff 《国际地质力学数值与分析法杂志》2016,40(9):1321-1338
The objective of this paper is to present a simplified method to determine the pile foundation system capacity based on the lower bound theorem of plasticity. The motivations for determining the lower bound capacity are the following: (1) to evaluate the accuracy of solutions based on the upper bound method; (2) to provide a conservative and efficient solution to the system capacity; and (3) to provide information about load distribution among individual piles at the verge of failure for the pile system. The failure mechanisms for a single pile and for the pile system are assumed to be two‐dimensional. For a typical long offshore pile, the upper and lower bound analyses produce identical lateral capacities. A simplified failure surface for loads at the single pile head is proposed and verified through analysis of 16 case study piles. With this proposed failure surface for a single pile, the lower bound failure load of the pile foundation system is obtained using the elastic compensation method enhanced with the linear matching method. Comparing with the existing upper bound and finite element solutions, the proposed lower bound method is capable of accurately and efficiently predicting the ultimate capacity of a pile foundation system. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
20.
针对深大基坑支护工程中存在的问题提出了一种新型的支护形式-剪力键支护体系,由竖直桩和斜向支撑的剪力键构成。通过模型试验,对剪力键组和单排悬臂桩组分别量测了不同开挖深度时的桩顶水平位移及桩身内力,同时进行了有限元的数值模拟。结果表明剪力键组的桩顶最大水平位移约为悬臂组的1/10,桩身最大弯矩值约为悬臂组的一半左右。剪力键支护体系具有更大的刚度,能够有效减小桩顶位移及桩身最大弯矩,且耗材相对较少,支护深度较大,占据空间较少,不影响主体地下室施工,可节约工期和成本,为深大基坑的支护提供了新的型式。 相似文献