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1.
Numerical simulation on floating behavior of buoyancy tank foundation of anemometer tower 总被引：1，自引：0，他引：1
The intact stability and damage stability of a model of an anemometer tower with buoyancy tank foundation are computed by the finite element software MOSES in this paper. The natural period of the anemometer tower is discussed through frequency domain analysis. The influence of a single factor, such as towing point position, wave height, wave direction and wave period, on towing stability is discussed through time domain analysis. At the same time, the towing stability under the condition of various combinations of many factors is analyzed based on the meas- ured data of the target area. Computer simulation results show that the intact stability is preferable and the damage stability is sufficient under the condition of plenty of subdivisions. Within the scope of the buoyancy tank foundation, the higher the towing point position is, the better the stability is. Wave height has a great impact on the motion amplitude of buoyancy tank foundation, but the effect on the acceleration is not obvious; wave period has a great impact on the acceleration, while the effect on the motion amplitude is not obvious; following-waves towing is more conducive to safety than atry. 相似文献
2.
An integrated finite element model(FEM)of offshore wind tower-foundation-soil is established by ABAQUS, where a large-scale composite bucket foundation with seven compartments inside is applied to supporting the upper wind tower. The dynamic response of the structure-foundation system is studied under three seismic waves with the same peak ground acceleration of 0.035g. It can be seen that the dynamic response increases at the beginning with the structure height, then it decreases because the structural damping increases due to the mass effect of the upper wind turbine generator system. It is shown that the anti-liquefaction capacity of the soil inside and underneath the foundation is improved owing to the high overburden pressure of the upper structure and the constraint effect of the bucket skirt and subdivisions. Moreover, the liquefaction resistance of the soil inside the middle compartment is improved to a higher degree than that inside the side compartments. 相似文献
3.
In 2010,the first offshore wind turbine with integrated installation was established in Qidong sea area of Jiangsu Province,China,which led to the implementation phase of one-step-installation technique based on the design and construction of large-scale bucket-top-bearing (LSBTB) bucket foundation.The critical technique of LSBTB bucket foundation included self-floating towing,penetration with adjustment of horizontal levelness,removability and one-step-installation.The process of one-step-installation included the prefabrication of LSBTB bucket foundation in onshore construction base,installation and debugging of wind power,overall water transportation of foundation and wind power system,and installation of foundation and offshore wind turbine on the appointed sea area.The cost of one-step-installation technique was about 5 000 Yuan/kW,which was 30%-50% lower than that of the existing technique.The prefabrication of LSBTB bucket foundation took about two months.During the one-step-installation process,the installation and debugging of wind power and overall water transportation need about one to two days in sea area within 35 m depth.After the proposed technique is industrialized,the cost will be further reduced,and the installation capacity is expected to be up to 500 wind turbines per year. 相似文献
4.
Numerical Analysis of Soil Plug Inside Suction Foundations During Suction Penetration by Discrete Element Method 总被引：2，自引：1，他引：2
The phenomenon of the soil plug usually rising inside the suction foundations during suction penetration was quantitatively described and predicted. The formation process of the soil plug was simulated and calculated by DEM （discrete element method） model. The seepage flow, the self-weight of soil, the friction on the chamber wall as well as the suction inside the chamber are considered as the main external forces in the process. The results are compared with a set of laboratory model tests performed by using three soil types （sand, silty clay and clay） in the Bohai Sea area. The heights of soil plug from numerical estimations are lower than those from model test results, mainly because the suction pressure and friction resistance are applied in an ideal way under the numerical simulation. 相似文献
5.
Design of offshore wind power foundation with multi-bucket 总被引：1，自引：0，他引：1
Three- and four-bucket offshore wind power foundations with a new form of force-transferring structure are proposed in this paper, and the integrated finite element model of foundation-soil-transition structure is established by using ABAQUS. The carrying capacity of the proposed foundations is studied under vertical load, horizontal load and bending moment. It can be seen that the vertical bearing capacity of multi-bucket foundation can be roughly estimated by the vertical bearing capacity of single-bucket; the horizontal bearing capacity of the three-bucket foundation scheme is controlled by displacement, while that of the four-bucket foundation scheme is controlled by the internal forces of soils. Moreover, the carrying capacity is provided by the overall structure formed by multi-bucket before soil failure. Compared with the conventional single-bucket foundation, there are mainly tension and pressure that are applied to the multi-bucket foundation, so that the carrying capacity of the foundation can be fully utilized. The probability of soil failure can be well reduced with the proposed multi-bucket foundation, and the stress transmission of force-transferring structure is more consistent through steel beams with variable cross-section. 相似文献
6.
The key in the force transmission between the tower and the foundation for offshore wind turbines is to transfer the large moment and horizontal loads.The finite element model of a large-scale prestres... 相似文献
7.
Cover-bearing-type bucket foundation for offshore wind turbines has been paid more and more attention due to its low cost and great bearing capacity. In order to ensure the cover-bearing mode, the muddy soil inside the bucket foundation should be reinforced by some soil consolidation methods, such as negative pressure and electro-osmosis. Firstly, tests were conducted to obtain the reasonable current density. Meanwhile, to improve the electro-osmotic speed and effectiveness, other factors such as intermittent power and layout of electrode, were also studied in the tests. Then, the soil reinforcing tests by negative pressure combined with electro-osmosis were performed for the muddy soil consolidation inside the bucket foundation. The results showed that soil reinforcement by negative pressure was quicker and more obvious during the early phase, and electro-osmotic method can affect more range of soil by rational arrangement of electrodes. Compared with negative pressure, the electro-osmotic method was a continuous and relatively slow process of reinforcement, which was complementary to the negative pressure method. The voltage value of electro-osmosis had little effect on the muddy soil reinforcement inside the bucket foundation, and 1.5 A was chosen as the most reasonable current value for scale model testing in the electro-osmotic method. 相似文献
8.
The early age performance of spread footing, especially the growth of cracks, is deeply influenced by the heat of hydration of cement. In this paper, 3D finite element method(FEM)models are set up to analyze the temperature distribution and thermal stresses of the spread footing during the first seven days after concrete placement. The mechanical properties of early age concrete are calculated, which are further used in the FEM models. The possibilities of crack growth are estimated by the method of crack index. The crack indexes of quite a number of points are very close to the allowable limit of 1.0 during the last three days. It is also indicated that the influence of foundation ring on the thermal stresses of concrete can be neglected. 相似文献
9.
Fatigue damage assessment is carried out considering mean value effect by applying four criteria of failure. Three frequency domain methods, i.e., level crossing counting(LCC), range counting(RC) and a new proposed method, are applied. The core of frequency domain method is the construction of probability density function for the mean stress and stress range of the stress process. The applicability of these frequency domain methods are inspected by comparing with time domain method. Numerical simulations verify the applicability of LCC and the proposed method, while RC gives poor estimations. 相似文献
10.
通过室内缩尺模型试验,比较和分析了嵌岩桩(RSP)和砂土桩在水平荷载下的承载能力.试验使用磷石膏来模拟底部岩石,采用夯实法制作上层砂土.试验前进行了颗粒分析试验以确认土壤的均匀程度.采用圆锥负荷试验(CPT)评估土壤,确认所有试验分组的土壤条件相似,即土体性质引起的误差可以忽略不计.通过有限元模拟对嵌岩桩的承载能力进行了验证,数值模拟结果与试验结果吻合良好.研究表明：嵌岩桩和砂土桩的弯矩分布一致,桩身最大弯矩的位置在2～3倍桩径深度处,但嵌岩桩的最大弯矩位置比砂土桩深约1倍桩径(5 cm);当上层覆土较浅时,嵌岩桩的承载效果更显著,承载力相对于砂土桩增加约41%;由于岩石的挤压效应,嵌岩桩的横截面变形明显小于砂土桩. 相似文献