离心机模型试验,混凝土在砂土上的承载能力-毕业论文外文翻译

附录A 外文文献及其翻译
Japanese Geotechnical Society Special Publication The 15th Asian Regional
Conference on
Soil Mechanics and Geotechnical Engineering Bearing capacity of hybrid suction foundation on sand with loading direction via centrifuge model test
Jae Hyun Kim i), Surin Kim i), Dong Soo Kim ii), Jun Ung Youn iii), Dong Joon Kim iv) and Sung Hyun Jee v)
i)P h.D Student, Department of Civil Engineering, KAIST, 291 Daehak-Ro, Yuseong-Gu, Daejeon,
305-701, Republic of Korea.
ii)Professor, Department of Civil Engineering, KAIST, 291 Daehak-Ro, Yuseong-Gu, Daejeon, 305-701, Republic of Korea.
iii)D irector, Hyundai Engineering and Construction Co., Ltd,446-912, Yongin-si, Republic of Korea.
iv)C hief research engineer, Hyundai Engineering and Construction Co., Ltd,446-912, Yongin-si, Republic of Korea.
v)General manager, Hyundai Engineering and Construction Co., Ltd,446-912, Yongin-si,
Republic of Korea.
ABSTRACT
Suction caisson is widely used to support offshore structure. However, this type of foundation may not provide sufficient resisting capacity economically under external loads. Recently, to give an increased capacity on the foundation, hybrid foundation concept was proposed to satisfy engineering needs as well as cost reduction of structures. Hybrid foundation concept is combination of skirted mat and suction caisson (s). Suction caisson (s) is fitted on the mat foundation intended to increase load capacity. This paper investigates the behavior of a hybrid suction foundation installed in sand layer for vertical and lateral loads, respectively. A series of centrifuge test have been conducted to assess the load capacity of the hybrid foundation and compared to those of the conventional single suction caisson. The primary goal of this study is to comprehend the effect of the mat compartment on foundation behavior under loading directions, and corresponding bearing capacity. Finally, feasibility of the hybrid foundation for offshore foundation was confirmed.
Keywords: suction caisson, hybrid foundation, bearing capacity, centrifuge modelling, sand
1 INTRODUCTION
Suction foundation is used in offshore industry world-wide as it can be installed by suction using differential pressure inside and outside the caisson, enabling the pre-loading in a short time as well as minimizing the need for additional equipment for the installation. As the
demands for offshore development, combined with the continue depletion of natural resources has resulted in offshore development moving beyond the shallow waters into deeper waters and harsh environments. In perspective of these situations, suction induced foundation (or anchor) is being considered to be the most efficient and robust solution for supporting offshore structures.
In offshore, the foundations are usually exposed by the various combinations of loadings. It may come from currents (waves), expansion / contraction of pipe lines linked to the structures due to the thermal changes before and after the operation or loads transferred from mooring lines. Typically, they applied on the structure in the horizontal forces with relatively small vertical load due to a low self-weight of the structure.
Suction caisson are large diameter steel cylinders with open ended at the bottom. In the design perspective, large diameter suction caisson is believed to provide higher holding capacity than small one toresist high external loads. However, manufacturing and transporting costs as well as installation are increased inefficiently. Therefore, new concept of suction caisson to increase the holding capacities while reducing the cost is needed.
Recently, hybrid suction foundation that combination of suction caisson (s) with large mat foundation to increase holding capacity while reducing structural cost has been considered. In some case, mat foundation with multi small suction caissons, called hybrid group suction foundation, can be alternative (Fig.1). Hybrid foundation concept and its benefit are well summarized in Gaudin et al. (2011) and Bienen et al (2011). Many studies related with holding capacity of hybrid foundation under various loading conditions in homogeneous clay have been investigated by using the numerical simulation and to a lesser by the centrifuge model test [Gaudin et al. (2011); Bienen et al. (2011; 2012); Dimmock et al. (2013) and Fu et al. (2014)]. However, the behaviour of the hybrid foundation with loading directions (or combined loadings) in the sand layer is not yet well understood.
In this paper, the behaviour of hybrid suction foundation placed on sand layer under uniaxial vertical and horizontal loadings was investigated using the centrifuge model test. The hybrid suction foundation which is combination of one suction caisson and the hopper over the container, nozzle size and falling height. Total three soil models with relative density, Dr = 60%, were prepared to a depth of 450 mm and performed six model tests in the samples. The resulting soil model conditions are tabulated in Table 2. The prepared soils were saturated at 1g by dribbling the water from the soil surface up to about 30 mm above the sample. The degree of saturation was enhanced by pre-spinning the model up to 70g in the centrifuge before the loading tests.
2 CENTRIFUGE MODEL TEST
2.1 Geo-centrifuge
A series of centrifuge model tests were performed using a beam-type geotechnical centrifuge installed at KAIST in Korea with 5 m radius. The maximum capacity of the
centrifuge is 240 g-ton and can be accelerated up to 130g. The detailed description of the facilities can be found in Kim et al. (2013).
2.2 Test apparatus and loading system
The load tests were conducted in the cylindrical container with inner diameter of 700 mm and 900 mm height at 70g-level. In order to apply the vertical and horizontal loads on the foundation, in a uniaxial form, respectively, loading systems were set up. To simulate the vertical load on the foundation, the model was connected to the driving part of linear actuator. Model and actuator were connected in a pin joint type with a pair of male and female, so that t h e m o d e l i s f r e e t o move vertically but restricted in horizontal direction. It makes possible to allow soil settlement while ramping up the centrifuge acceleration. Horizontal load was simulated by adopting the pulleys and wire system. The drive unit was mounted on a container to be moved horizontally and linked to the model foundation using a chain through pulleys fixed at the container wall. Thus, pure horizontal load was applied on the top of foundation by displacing an actuator position with constant rate, drawing the foundation horizontally. The manufactured miniature loadcell was connected between the chain and the caisson with
pin-joint type such that the horizontal load was directly measured at very close the model. Two laser sensors were positioned at the different level. Thus, displacement or rotation of the foundation was monitored of thin and light plate standing on the model. In addition, the images was captured at same interval in front of the model during the test to perform the image analysis. Suction caisson Actuator LVDT Load-cell Pin
Actuator Pulley Wire Load cell Laser sensors Load cell Suction caisson
2.3 Model description
Two types of model were prepared to perform a series of tests; conventional suction caisson and single suction caisson with circular mat. Single suction foundation have caisson outer diameter (D c ) m of 71.4 mm with 3 mm thickness (t c ) m , corresponding to prototype dimension (D c ) p = 5 m and (t c ) p = 210 mm. Caisson length to diameter ratio (L/D c ) is 1. The thickness of the model was over-designed than the typical prototype caisson dimension by concern for structure failure during the tests (typically, t c /D c = 0.3 ~ 0.4% for sand, Tran and Randolph (2008)). Hybrid
foundation have same dimensions with those of the single caisson model and the mat dimension of D m = 142.8 mm, representing a prototype of (D m ) p = 10 m. the dimension of foundation are summarized in Table 1. Table 1. Dimensions of the model foundations.
2.4 Soil sample
The clean silica sand material, which is mainly comprised with quartzite, was used in this study. The soil properties of the sand used in this study are; specific gravity G s = 2.65, mean grain size (D 50 ) = 0.237, maximum dry density, γ max = 1.64 and minimum dry density, γ min = 1.24.
Dry sand were prepared by a pluviation method using an automated sand rainer. Homogeneous sand layer was achieved by controlling the travel speed of the hopper over the container, nozzle size and falling height. Total three soil models with relative density, D r = 60%, were prepared to a depth of 450 mm and performed six model tests in the samples. The
resulting soil model conditions are tabulated in Table 2. The prepared soils were saturated at 1g by dribbling the
water from the soil surface up to about 30 mm above the sample. The degree of saturation was enhanced by pre-spinning the model up to 70g in the centrifuge before the loading tests.
2.5 Testing program
Total six tests were performed in the three soil samples. In the Sample 1, two vertical loading tests were conducted on the single and hybrid foundations, respectively (denoted as Test 1 and Test 4). In the sample 3, two horizontal load test were conducted by using the two caissons (Test 3 and Test 6). Here, the tests were carried out in the conditions that the base (or mat) of the caissons is completely contacted to the ground. In the sample 2, the same tests done in sample 3 were conduct except that the mat (or base) is not attached to the ground surface (Test 2 and Test 5). In each sample, the tests for each model foundation in the sample were performed under same boundary condition and the spacing between the models.
All of the model foundations were installed up to predetermined depth by jacking using the vertical actuator at a constant rate of 1 mm/sec at 1g. After installation of the foundation, centrifuge was ramped up to 70g in steps. Then, the model foundation was displaced in the load directions with 0.05 mm/sec, ensuring fully drain condition during the load tests as recommended by Finnie and Randolph (1994).
The results are discussed following the sign and symbol adopted by Butterfield et al. (1997). The reference point is located at the soil surface in this study.
Table 2. Test conditions.
Foundation Loading Loading γd
Test ID type direction rate(kN/m3)Remark4)
Test 11)V14.6Detached
Test 22) Conventional H14.7Detached Test 33)H0.0514.7Attached
Test 41)V mm/sec14.6Detached Test 52) Hybrid H14.7Detached Test 63)H14.7Attached
Note: 1) sample 1; 2) sample 2; 3) sample 3,
4) whether the foundation base (or mat) fully attached to the soil surface or not.
3TESTING RESULTS AND DISCUSSIONS
3.1 Ultimate vertical capacity
Vertical holding capacity of suction foundation was investigated. All the results are also discussed in a prototype scale. Figure 3 presents two load -displacement curves observed in the displacement - controlled vertical loading tests. Vertical loads are also
plotted against normalized displacement, d/D c, as well as bearing capacity factor, 2V/Aγ’D c, where A is area of suctions caisson, in a dimensionless form.
The load-displacements observed in vertical loading tests were monotonically increased with penetration without mobilization of peak strength, which reflect the characteristics of punching behavior. In addition, it is evident that the vertical bearing capacity of the hybrid foundation is higher than the conventional caisson due to mat foundation with enlarged area. For Test 4, the load-displacement shape was changed in around d/Dc =
0.07 (denoted as symbol ① in Fig. 3) where the mat is fully attached on the soil surface. Thereafter, load was dramatically increased (denoted as symbol ①).
Ultimate bearing capacity were determined where the tangential intersection of two linear lines parallel to the initial and later parts of the measurement and its corresponding point of the curves (see, red dots in Fig. 3). The determined ultimate bearing capacities show
V ult = 81 MPa (2V/Aγ’Dc =113) at d/Dc = 0.21 for Test 1 and Vult = 155 MPa (2V/Aγ’Dc = 216) at d/Dc = 0.21 for Test 4. The ultimate bearing capacity of hybridfoundation is about 1.91 times larger value than the value of conventional suction foundation.
3.2 Ultimate horizontal capacity
Figure 4 presents the bearing capacity for the horizontal loading for conventional single caisson and hybrid foundation. Horizontal displacement of the caisson at the reference point is calculated from measurements of two laser sensors positioned at different levels.
All the curves reaches a plateau. Results show that the horizontal load capacities of hybrid foundation are much higher than those of the single suction caisson. It may come from the mat foundation which aids the resisting force from the external load by extending the resisting area. The determined ultimate horizontal capacities are summarized in Table 3. It is noteworthy that the load-displacement trend of Test 5 in a condition that the mat foundation is not fully contacted with the ground surface, shows double curvature shape. This trend is contrary to the behavior of Test 6 in a condition of fully contact between the mat and ground. It can be explained by the rotation behavior of the foundation. Firstly, only the part of caisson resisted horizontal load because the mat was detached from the soil surface as
denoted in Fig. 4 (see, symbol ①). As the load increases, the foundation began to rotate, and the protruded mat beyond the caisson initiated to intrude
into the ground surface (Fig. 4, see ①). Finally, the mat was completely penetrated into the ground and full holding capacity of the hybrid foundation was reached. It can actually happen in the field because the soil heaving may occur during the suction installation process so that the caisson can’t penetrate up to the full penetration (Houlsby and Byrne, 2005).
For Test 6, unlike the Test 5, horizontal load continuously increased and reached to the ultimate holding capacity. The different rotation behavior could be confirmed by the captured images with same interval during the tests as shown in the Fig. 5.
3.4 CONCLUSIONS
Centrifuge test have been conducted to explore the feasibility of hybrid suction foundation for the offshore structure in sand. The ultimate bearing capacities for the vertical and horizontal loadings were assessed by using the model tests. From a series of test, hybrid foundation which is combination of the circular mat and suction caisson, shows the potential as an alternative subsea foundation by providing enhanced holding capacities.
The results also showed different behavior with the attached condition between the mat and soil surface. However, additional analyses would be required to confirm the effect of interaction between the mat and soil on the capacities. Further investigation for the hybrid foundation is currently on-going. With the centrifuge model tests, finite element analysis is conducting in parallel to investigate the bearing capacity with the loading directions and to validate the test results.
4.ACKNOWLEDGEMENTS
This study was supported by a grant from the Future Flagship R&D Program (10042452) of Korea Minis-try of Trade Industry and Energy “Engineering Technology Development for the 3,000m Deepwater Subsea Equipment and URF Installation to advance to Deepwater Offshore Plant Market” project. The authors also thanks to the collaborations of Hyundai Engineering and Construction, Co., Ltd.
REFERENCES
1)Bienen, B. et. al. (2011): Numerical study of the combined load capacity of a hybrid foundation, Proc. Int. Symp. Off.and Pol. Eng., ISOPE2011, Maui, Hawai, USA, 556-562.
2)Butterfîeld, R., Houlsby, G. T., and Gottardi, G. (1997): Standardised sign conventions and notation for generally loaded foundations, Géotechnique, 47(4), 1051–1052.
3)Dimmock, P. et al. (2013): Hybrid subsea foundations for sub-sea equipment, Journal of Geotechnical and Geoenviron-mental Engineering, 139(12), 2182-2192.
4)Finnie, I.M.S., and Randolph, M.F. (1994): Punch-through and liquefaction induced failure of shallow foundations on calcareous sediments, Proc. of Int. Conf. on Behaviour of Off-shore Structures, Boston, USA, 217-230.
5)Fu, D. et al. (2014): Undrained capacity of a hybrid subsea skirted mat with caissons under combined loading, Canadian Geotechnical Journal, 51, 934-949
6)Gaudin, C. et al. (2011): Centrifuge experiments of a hybrid foundation under combined loading, Proc. Int. symp. Off. and Pol. Eng, ISOPE 2011, Maui, Hawai, USA. 386-392.
7)Houlsby, G. T., and Byrne, B. W. (2005): Design procedures for installation of suction caissons in sand, Proceedings of the ICE-Geotechnical Engineering, 158(3), 135-144.
8)Kim, D.S. et al. (2013): A newly developed state-of-the-art geotechnical centrifuge in Korea, KSCE Journal of Civil Engineering, 17(1), 77-84.
9)Tran, M. N., and Randolph, M. F. (2008): Variation of suction pressure during caisson installation in sand,
Géotechnique, 58(1), 1-11.
离心机模型试验，混凝土在砂土上的承载能力
摘要
沉箱广泛用于支持海上结构。

然而，这种类型的地基在外部负载下不能有效地提供足够的耐受能力。

最近，为了在基体上增加能力，提出了混合基体概念以满足工程需要以及结构的成本降低。

混合基础概念是裙边垫和沉箱的组合。

吸力沉箱安装在垫基础上，用于增加承载能力。

本文研究了安装在垂直和侧向荷载的砂层中的混合吸力基础的行为。

已经进行了一系列离心机测试以评估混合基础的负载能力并与常规单吸入沉井相比。

这项研究的主要目的是了解垫隔间对加载方向下的基础行为的影响，以及相应的承载能力。

最后，确定了海上基础混合基础的可行性。

关键词：吸力式沉箱，混凝土地基，承载能力，离心机模型，砂
引言
吸入基座用于全世界的海上工业，因为它可以通过使用沉箱内部和外部的压差进行抽吸来安装，使得能够在短时间内预加载以及最小化对于安装的附加设备的需要。

随着对海上开发的需求，以及自然资源的持续枯竭，使得海上开发超越浅水区，进入更深的水域和恶劣的环境。

从这些情况的角度来看，吸力诱导地基（或锚）被认为是支持海上结构的最有效和可靠的解决方案。

在海上，地基通常通过各种装载组合暴露。

它可能来自电流（波），由于操作前后的热变化或从系泊线传递的负载而连接到结构的管线的膨胀/收缩。

通常，由于结构的低自重，它们在具有相对小的垂直负载的水平力中施加在结构上。

吸力沉箱是底部开口的大直径钢制气瓶。

在设计透视图中，大直径吸力沉箱被认为提供比小型吸力箱更高的保持能力抵抗高外部负载。

然而，制造和运输成本以及安装都低效地增加。

因此，需要新的抽吸沉箱的概念以增加保持能力同时降低成本。

近来，已经考虑了混合吸力基础，其将吸力沉箱与大垫基础结合以增加保持能力同时降低结构成本。

在一些情况下，具有多个小吸力沉箱的垫基础，称为混合组吸入基础，可以是可选择的（图1）。

混合基础概念及其好处在Gaudin 等人（2011）和Bienen等（2011）。

许多关于混合基础在均匀粘土中各种负载条件下的保持能力的研究已经通过使用数值模拟进行了研究，并通过离心机模型试验进行了较少研究[Gaudin 等。

（2011）; Bienen等人（2011; 2012）; Dimmock 等。

（2013）和Fu 等人。

（2014）]。

然而，混凝土基础与砂层中的加载方向（或组合加载）的行为还没有被很好地理解。

在本文中，使用离心机模型试验研究了置于单层垂直和水平荷载下的砂层上的混合吸力基础的行为。

考虑了一种吸力基座，其结合了一个吸力沉箱和连接在沉箱顶部的圆形垫子。

为了比较，同样直径的传统单吸力沉箱的行为与混合基础的行为也被调查和比较彼此。

此外，垫埋入土壤表面对保持行为的影响，也进行了研究。

实际上，这是在现场发生的真实情况，因为吸力基础可能没有完全渗透到地面，当安装由吸力由于沉积在沉箱内的土壤。

图1.各种吸力沉箱类型：（a）单沉箱，（b）混合式地基（具有单沉箱的圆形垫）和（c）
混合组地基（具有多吸力沉箱的正方形垫）
2离心机型号试验
2.1地质离心机
使用安装在韩国KAIST的梁式土工离心机进行一系列离心机模型试验，其中半径为5m。

离心机的最大容量为240 g-ton，可加速到130g。

设施的详细描
述可以在Kim et al。

（2013年）。

2.2试验装置和装载系统
负荷试验在内径为700mm，高度为900mm，高度为70g的圆柱形容器中进行。

为了将垂直和水平载荷分别以单轴形式施加在基础上，建立了装载系统。

为了模拟基础上的垂直载荷，将模型连接到线性致动器的驱动部分。

型号和执行机构用一对公和母连接成销接型，因此模型可以自由地垂直移动但在水平方向受到限制。

它可以允许土壤沉降，同时提高离心机加速度。

采用滑轮和钢丝系统模拟水平荷载。

驱动单元安装在容器上以水平移动并使用固定在容器壁处的链条通过滑轮链接到模型基础。

因此，通过以恒定速率移动致动器位置，在水平方向上拉伸基础，在地基的顶部施加纯水平负载。

制造的微型
称重传感器连接在链和沉箱之间，使用pin接头类型，使得在非常接近模型时直接测量水平负载。

两个激光传感器位于不同的水平。

因此，监测位于模型上的薄板和轻板的基础的位移或旋转。

此外，在测试期间在模型前面以相同的间隔捕获图像以进图像分析。

图 2.垂直和水平装载的装载系统方案：（a）垂直装载系统（b）水平加载系统
2.3模型描述
准备两种类型的模型以执行一系列测试;传统吸力沉箱和单吸力沉箱与圆
形垫。

单吸型地基的沉箱外径（D c）m为71.4 mm，厚度为3 mm（t c）m，对
应于原型尺寸（D c）p = 5 m和（t c）p = 210 mm。

考虑到试验期间的结构破坏，模型的厚度超过典型的原型沉箱尺寸（通常，tc / D c = 0.3〜0.4％，对于沙，Tran和Randolph（2008））。

混合基础具有与单一沉箱模型和垫尺寸D m = 142.8mm的尺寸相同的尺寸，代表（D m）p = 10m的原型。

基础的尺寸总结在表1中。

2.4土壤样品
在本研究中使用主要由石英岩组成的干净的硅砂材料。

本研究中使用的砂土性质为：比重G s = 2.65，平均粒径（D 50）= 0.237，最大干密度，γmax = 1.64和最小干密度，γmin = 1.24。

通过使用自动砂磨机的沉淀法制备干砂。

通过控制料斗在容器上的行进速度，喷嘴尺寸和下落高度来实现均匀砂层。

将相对密度
D r = 60％的三个土壤模型制备成深度为450mm，并在样品中进行六个模型测试。

所得土壤模型条件列于表2中。

通过将来自土壤表面的水递送至样品上方约30mm，使制备的土壤在1g处饱和。

通过在负载测试之前在离心机中将模型预旋转至70g 来增强饱和度。

2.5测试程序
在三个土壤样品中进行总共六个测试。

在样品1中，分别对单个和混合基础进行两个垂直负载试验（表示为试验1和试验4）。

在试样3中，使用两个沉箱
进行两个水平负荷试验（试验3和试验6）。

这里，在沉箱的基底（或垫）完全
接触地面的条件下进行测试。

在样品2中，除了垫（或基底）未附着到地面（测试2和测试5）之外，在样品3中进行的相同测试。

在每个样本中，样本中每个模型基础的测试在相同的边界条件和模型之间的间距下进行。

通过使用垂直致动器以1g / sec的恒定速率1mm / sec顶起，将所有模型基础安装到预定深度。

在安装基础之后，将离心机逐步升至70g。

然后，模型基础在负载方向上以0.05mm / sec移位，确保在负载测试期间完全排水条件，如Finnie和Randolph（1994）所推荐的。

结果在Butterfield等人采用的符号和符号后讨论。

（1997）。

在本研究中，参考点位于土壤表面。

3测试结果和讨论
3.1极限垂直能力
研究了吸力基础的垂直承载能力。

所有的结果也在原型规模讨论。

图3给出了在位移控制垂直载荷试验中观察到的两个载荷 - 位移曲线。

垂直载荷也以标准化位移d / D c以及承载能力因子2V / Aγ'Dc绘制，其中A是吸力沉箱的面积，以无量纲的形式。

在垂直荷载试验中观察到的载荷位移单调增加，没有峰值强度的移动，这反映了冲压性能的特性。

此外，由于地基扩大，混凝土基础的垂直承载力明显高于常规沉井。

对于试验4，在垫子完全附着在土壤表面上的d / D c = 0.07（在图3中表示为符号①）附近改变载荷 - 位移形状。

此后，负荷急剧增加（表示为符号②）。

确定极限承载力，其中平行于测量的初始部分和稍后部分的两条线性直线的切线交叉点和其曲线的对应点（参见图3中的红点）。

对于测试1，d / D c = 0.21时测得的极限承载能力显示V ult = 81MPa（2V /A
γ'Dc = 113），在d /对于试验4，D c = 0.21。

混合式基础的极限承载力比常规吸力基础的值大约1.91倍。

图3.具有穿透的垂直负载曲线
3.2极限水平容量
图4显示了传统单沉箱和混凝土基础的水平荷载的承载能力。

由位于不同水平的两个激光传感器的测量计算沉箱在参考点处的水平位移。

所有曲线达到平台。

结果表明，混凝土基础的水平荷载能力远大于单吸力沉箱的水平荷载能力。

它可以来自通过延伸抵抗面积来辅助来自外部负载的抵抗力的垫基础。

确定的最终水平能力总结在表3中。

值得注意的是，试验5在垫子基座未与地面完全接触的情况下的载荷 - 位移趋势显示出双曲率形状。

这种趋势与试验6在垫子和地面之
间完全接触的情况下的行为相反。

这可以通过基础的旋转行为来解释。

首先，只有沉箱的部分抵抗水平荷载，因为垫子从土壤表面分离，如图1所示。

4（参见符号①）。

当载荷增加时，基础开始旋转，并且超出沉箱的突出的垫开始侵入地表（图4，参见②）。

最后，垫子完全渗透到地面中，达到了混凝土基础的完全保持能力。

它实际上可能发生在现场，因为土壤沉积可能发生在吸入安装过程中，使沉箱不能渗透到全渗透（Houlsby和Byrne，2005）。

对于测试6，与测试5不同，水平负载连续增加并达到最终保持容量。

不同的旋转行为可以通过在如图1所示的测试期间具有相同间隔的捕获图像来确认。

图4.具有穿透的水平负载曲线
表3。

地基极限承载力
注：1）地基（或垫）沉箱完全附在土壤；
2）在土壤上分离。

图 5.水平荷载试验的图像捕获：（a）试验6和（b）试验5
4.结论
已进行离心试验，探讨混凝土吸力基础对于海上结构的可行性。

通过使用模型试验评估垂直和水平荷载的极限承载能力。

从一系列的测试，混合基础是圆形垫和吸力沉箱的组合，通过提供增强的保持能力显示了作为替代海底基础的潜力。

结果还表明垫与土壤表面之间的附着条件具有不同的行为。

然而，需要进行额外的分析以确认垫和土壤之间的相互作用对容量的影响。

对混合基础的进一步调查目前正在进行。

利用离心机模型试验，并行进行有限元分析以研究承载能力与载荷方向，并验证试验结果。

致谢
这项研究得到了来自韩国贸易工业和能源研究所的未来旗舰研发计划（10042452）“3,000米深水海底设备的工程技术开发和URF安装前进到深水海
洋工厂市场”项目的资助。

作者还感谢现代工程建设有限公司的合作。

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