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1.
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
2.
The large-scale bucket foundation with 30 m in diameter and 6 m in height was used as the foundation of wind turbine.The wide-shallow foundation is different from the traditional bucket foundation with... 相似文献
3.
Bucket foundations[1 ,2]are a relatively newtype offoundation usedto support offshore structures .Each bucketfoundation consists of a thin cylindrical steel shell ,cappedwithalid of steel or concrete .Thefoundationcan penetrateinto sea floor when pumping … 相似文献
4.
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
5.
强夯法处理湿陷性黄土地基具有施工简便、快速有效、造价经济、质量可靠的优点.它对增强地基密实度、消除土层湿陷性、降低土层压缩性和提高地基承载力效果显著.针对某仓库地基强夯工程,对强夯加固效果进行分析,采用文中建议的公式计算夯后地基承载力,理论计算值与实测值基本吻合. 相似文献
6.
强夯法在高速公路软土地基中的加固效果研究 总被引：1，自引：0，他引：1
蒋红 《廊坊师范学院学报(自然科学版)》2013,(6):73-75
强夯法是我国软土地基加固处理的常用方法,但其加固效果如何需要进一步的实践和研究。对具体加固实例的实测结果和试验数据分析表明,实施强夯后的软土地基在提高地基承载力、减少土体压缩性、降低湿陷性等方面效果明显。 相似文献
7.
To investigate the natural frequencies and towing behaviors of a 3-bucket foundation platform at different drafts, the decay and towing experiments were carried out in a towing tank on a scale of 1:20. The air pressure inside the bucket foundations, the water pressure at the bottom of the bucket foundations, the acceleration of the platform and the towing force were determined in the test process. The time-history curves of the measured parameters were obtained, and the frequency responses of the parameters at different drafts were analyzed by means of fast Fourier transform(FFT). The results showed that the platform natural frequency of heave decreased slightly with the rise of draft. The natural frequencies of roll and pitch are much lower than that of heave, and they increased slightly with the increase of draft. When towing in the following sea, the maximum acceleration of surge, sway and heave has downward trends with the increase of draft, but the change range decreased gradually with the increase of draft. When the draft is 5.0 m(the ratio of draft to bucket height is 0.56), the towing dynamic responses achieve the maximum, which is not conducive to the towing of the platform. When the draft is 6.0 m(the ratio of draft to bucket height is 0.67), the towing dynamic responses are the most stable. 相似文献
8.
On the dissipation of negative excess porewater pressure induced by excavation in soft soil 总被引：3，自引：0，他引：3
INTRODUCTION Since Terzaghi founded his one-dimensionalconsolidation theory, the studies on consolidation ofsoft soil have been made by many researchers (Gray,1945; Gibson et al., 1967; 1981; Schiffman and Stein,1970; Xie, 1994; Xie et al., 2002a). However, al-though as we all know, negative excess porewaterpressure will be induced by unloading in excavation,the dissipation of the negative pressure and its effectsare rarely studied because of their complexity (Chenand Wen, 1999; … 相似文献
9.
复合地基在地基处理中具有十分重要的地位,其用于加固地基,增强地基承载力和减小地基沉降具有良好的效果,因而在工程中被广泛采用。由于研究复合地基的固结是研究复合地基加固机理的主要内容之一,土体的固结直接影响复合地基的变形和承载能力。因此,有必要对复合地基的固结理论进行全面、系统地认识。本文主要对散体材料桩和水泥桩复合地基的固结理论进行综述,阐述了复合地基固结理论研究的现状和取得的理论成果。 相似文献
10.
Numerous experiments have shown that the water flow in fine-grained soils can obey an exponential relationship at small gradients and a linear relationship when the hydraulic gradient exceeds a certain limit. Based on the non-Darcian flow described by exponent and threshold gradient, the theory of 1D consolidation is modified in this paper to consider a linear variation in the vertical total stress with depth and the effect of ramp loading. The numerical solutions were derived in detail by the finite difference method for excess pore water pressure and the average degree of consolidation. Finally, the influence of various parameters on consolidation behavior was investigated. The results show that the rate of consolidation is reduced when non-Darcian flow described by exponent and threshold gradient is adopted in the theory of 1D consolidation. As well the distribution of vertical total stress has a great influence on the dissipation of excess pore water pressure, either for pervious top and pervious bottom （PTPB） or for pervious top and impervious bottom （PTIB）. For the case of PTIB, the distribution of vertical total stress in a foundation has a great influence on the rate of consolidation; however, for the case of PTPB, the rate of consolidation is independent of the distribution of vertical total stress. The rate of consolidation is dependent on the ratio of the thickness of a soil layer to the equivalent head of the final average vertical total stress; the greater the value of this ratio, the slower the rate of consolidation. Finally, an increase in construction time reduces the consolidation rate of a foundation. Thus, consolidation behavior of 1D consolidation with non-Darcian flow has been thoroughly acquainted in this paper. 相似文献
11.
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
12.
软土场地与静压预制桩的压桩力控制 总被引：1，自引：0，他引：1
论述静压预制桩压桩力对地表土层和下卧软土层承载能力的要求。在建立两者之间关系时，考虑压入土中桩的挤土效应对软土结构的破坏和因此引起的承载能力的降低。提供了不同型号压桩机在不同表土层厚度条件下，对含水量不同的软土层的许用压桩力的粗略定量解答。 相似文献
13.
盘锦市体育中心地质情况表现为在地下14m范围内存在粉砂夹粉质粘土土层,在地震荷载作用下,将会产生砂土液化现象。针对这一情况,采用了碎石桩复合地基进行处理,处理后地基液化现象基本消除,地基承载力也满足要求。工程完工后,运行情况良好。 相似文献
14.
The consolidation behavior of mixed in place cement- and lime/cement-mixed column was studied. Consolidation of the composite
foundation was modeled as a three-dimensional axi-symmetric problem. The authors used the finite difference method to obtain
the pore pressure variation with time at any location below the surface. A computer program developed by the authors was used
to draw some interesting conclusions about the consolidation behaviors of cement- and lime/cement-mixed pile foundation. Finally,
a combined model including the permeability coefficients of cement-mixed piles and soil, was studied and its feasibility was
evaluated.
Project supported by National Natural Science Foundation of China (No. 59908012) and Education Ministry of China 相似文献
15.
真空预压技术加固海堤深厚软基原型试验研究 总被引：4，自引：0，他引：4
真空荷载提供了一种减少堤坝软土地基固结时间的选择. 本文开展了一个海堤全断面的试验及原型观测研究. 试验堤高5. 5 m, 22 m深且三角形布置的塑料排水板作为竖向排水通道, 现场布置了水平测斜和沉降仪等观测仪器, 埋设在不同地基深度的孔隙水压力计用来量测真空-堆载联合荷载下的地基中超静孔隙水压力的变化. 通过场地条件分析、高真空度维持和真空卸载, 得到了系统的沉降变形和孔隙水压力资料, 试验结果验证了真空-堆载联合预压加固海堤软土地基的效果. 相似文献
16.
本文用深搅桩复合地基的指数模型,建立了与之相应的昆明地区复合地基承载力经验公式,用经验公式估算的复合地基承载力预测值与实测值作比较,其结果可满足工程精度要求. 相似文献
17.
Bearing Capacity and Technical Advantages of Composite Bucket Foundation of Offshore Wind Turbines 总被引：1，自引：1，他引：0
Based on mechanical characteristics such as large vertical load,large horizontal load,large bending moment and complex geological conditions,a large scale composite bucket foundation (CBF) is put forward.Both the theoretical analysis and numerical simulation are employed to study the bearing capacity of CBF and the relationship between loads and ground deformation.Furthermore,monopile,high-rise pile cap,tripod and CBF designs are compared to analyze the bearing capacity and ground deformation,with a 3-MW wind generator as an example.The results indicate that CBF can effectively bear horizontal load and large bending moment resulting from upper structures and environmental load. 相似文献
18.
黄玉宁郑永乾赖鹏松 《福建工程学院学报》2020,(4):329-335
采用有限元软件ABAQUS建立了不同加载角T形带肋和多室钢管混凝土压弯构件的计算模型,数值计算结果与试验结果吻合良好。对影响T形钢管混凝土柱水平荷载P-水平位移Δ关系曲线的参数进行分析,结果表明:加载角为0°时,T形钢管混凝土构件的承载力最低,在67.5°负向加载时,构件的承载力最大,比0°加载角构件大13%左右,加载角为45°~90°间承载力总体上差别不大。随着钢管屈服强度、混凝土抗压强度、钢管长厚比、带肋和多室T形钢管混凝土构件在斜向加载的承载力增加,在传统钢管混凝土基础上,提出了适用于不同加载角带肋和多室T形钢管混凝土压弯构件的承载力设计方法,简化计算公式与有限元结果、试验结果均吻合较好。 相似文献
19.
林智勇 《福建工程学院学报》2016,(4):318-323
利用数值分析方法建立了软土地基模型,采用比奥固结理论,计算分析了真空预压下的软土地基流固耦合作用;并进一步分析了真空度损耗率、密封墙、塑料排水板打设深度等因素对软基加固效果的影响。分析结果表明:在抽真空早期,地表沉降增长很快,达到一定天数后,沉降值逐渐趋于稳定;真空负压沿深度、水平方向上损耗,在加固软土外围形成一个零孔隙水压力面;真空度损耗率、塑料排水板打设深度对真空预压加固软土的效果影响很大;侧向密封墙对加固区内土体影响不大,但其限制了真空负压的侧向传递,使影响区的地基沉降大幅减小。 相似文献
20.
某拟建场地位于山脊山谷地带切削填平的土质边坡上,该边坡总体高度36.4 m,为超高填土边坡,按照规范要求,该类边坡应进行特殊设计。考虑到边坡的自重固结尚未完成,承载能力较低,在工程地质勘查和室内试验获得的土体物理力学性质的基础上,采用FLAC3D对该边坡的场地适宜性进行了数值模拟分析。结果表明：该边坡在自重固结作用下或施加拟建建筑荷载后,产生较大的竖向沉降和水平位移,直接作为建筑场地将存在较大的隐患,需要结合桩锚联合支护等方案进一步研究探讨。 相似文献