scholarly journals Model Tests of Soil Reinforcement Inside the Bucket Foundation with Vacuum Electroosmosis Method

2019 ◽  
Vol 9 (18) ◽  
pp. 3778 ◽  
Author(s):  
Hanbo Zhai ◽  
Hongyan Ding ◽  
Puyang Zhang ◽  
Conghuan Le
Keyword(s):  
Shear Strength ◽  
Moisture Content ◽  
Bearing Capacity ◽  
Soil Moisture Content ◽  
Soil Reinforcement ◽  
Vacuum Preloading ◽  
Bucket Foundation ◽  
Capacity Model ◽  
Vertical Bearing ◽  
Vertical Bearing Capacity

Offshore wind turbine foundations are commonly subjected to large horizontal, vertical, and bending moment loads. Marine soils have high moisture content, high compressibility, high sensitivity, and low strength, resulting in insufficient foundation bearing capacity. In order to improve the bearing capacity of wind turbine foundations and reduce foundation settlement, an internal vacuum preloading method combined with electroosmosis reinforcement is used to reinforce the soil within bucket foundations. The pore water pressure, vertical settlement, pumping quality of the soil during the reinforcement process, soil moisture content before and after the reinforcement, and undrained shear strength were analyzed. Horizontal and vertical bearing capacity model tests were carried out on the reinforced and nonreinforced soil inside the bucket foundation. Results show that vacuum preloading combined with electroosmosis reinforcement reduces soil moisture content inside the bucket foundation by approximately 20%, and the undrained shear strength of the internal soil increases by approximately 20 times. Soil reinforcement has high spatial uniformity. Results of the bucket foundation bearing capacity model show that when the soil inside the bucket foundation is strengthened, horizontal bearing capacity increased by 2.9 times and vertical bearing capacity increased by 2.1 times. Vacuum preloading combined with electroosmosis reinforcement can effectively improve the shear strength of soft soil and enhance the bearing capacity and stability of bucket foundations.

The Experiment on how the Ratio of Diameter to Height D/H Influences the Bearing Capacity of Bucket Foundation

2014 ◽  
Vol 488-489 ◽  
pp. 629-634
Author(s):  
Shuai Liu ◽  
Wen Bai Liu ◽  
Liang Yang
Keyword(s):  
Bearing Capacity ◽  
Ultimate Strength ◽  
Bucket Foundation ◽  
S Curve ◽  
Vertical Bearing ◽  
Room Model ◽  
The Cost ◽  
Vertical Bearing Capacity ◽  
Maximum Utilization ◽  
Ultimate Displacement

Through eight groups of room model experiments based on bucket foundation, P-S curve can be plotted for each group according to the experiments results and be able to get the ultimate strength and ultimate displacement for them. Therefore how the ratio of the ultimate vertical bearing capacity and the ultimate displacement changes with the ratio of diameter to height can be analyzed. When the ratio of diameter to height is less than 1.2, the ratio of the ultimate vertical bearing capacity and the ultimate displacement changes significantly; and when the ratio of diameter to height is greater than 1.2, the ratio of ultimate vertical bearing capacity and ultimate displacement is not affected obviously. When the ratio of diameter to height is 1.2, it reaches the maximum utilization of the materials, and the cost of the project can be effectively reduced. So the paper considers that the ratio of diameter to height = 1.2 can be used as the optimum point of the ratio of diameter to height of the bucket foundation.

Study on Vertical Bearing Capacity of the Wide-Shallow Bucket Foundation in Two Layered Sand

2020 ◽  
Author(s):  
Guodong Sun ◽  
Run Liu ◽  
Jijian Lian ◽  
Runbo Cai ◽  
Xu Yang ◽  
...  
Keyword(s):  
Internal Friction ◽  
Bearing Capacity ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Unit Weight ◽  
Offshore Wind Turbine ◽  
Sand Layer ◽  
Bucket Foundation ◽  
Vertical Bearing ◽  
Vertical Bearing Capacity

Abstract The wide-shallow bucket foundation proposed by Tianjin University of China is a new type of offshore wind turbine foundation. In this paper, the vertical bearing capacity of wide-shallow bucket foundation embedded in two layered sand that contains an underlying medium strength sand layer and a weaker or stronger overlaying sand layer is studied. A parametric study for bearing capacity is carried out with the ratio of unit weight γ1/γ2 (where γ1 and γ2 are the unit weight of the upper and lower sand layers respectively), the ratio of internal friction angle φ1/φ2 (where φ1 and φ2 are the internal friction angle of the upper and lower sand layers respectively) and relative thickness of the top sand layer H1/B (where H1 and B are the thickness of the top sand layer and the bucket foundation diameter). All of the presents were performed by the Finite Element Method and the results show that the thickness of the top layer has a great influence on the vertical bearing capacity of the foundation. Specifically, the upper sand layer is stronger, the bearing capacity ascends with the increase of the thickness of the top layer, and on the contrary, the upper layer is weaker, and the bearing capacity decreases with the increase of the top layer thickness. In addition, the bearing capacity of the foundation also increases with the ratios of the effective unit weight and the internal friction angle.

Upper Bound Solutions of Vertical Bearing Capacity of a New Type Bucket Foundation in Sand

2014 ◽  
Author(s):  
Run Liu ◽  
Guangsi Chen ◽  
Hongyan Ding ◽  
Jijian Lian
Keyword(s):  
Bearing Capacity ◽  
Wind Turbine ◽  
Upper Bound ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Empirical Parameter ◽  
Number Range ◽  
Bucket Foundation ◽  
Vertical Bearing ◽  
Vertical Bearing Capacity

Offshore wind turbine is a new solution of the energy crisis, and stable foundation is an important guarantee for its safety. An important characteristic of wind turbine foundation is to bear the vertical load, horizontal load and moment at runtime. A large diameter wide-shallow bucket foundation, as a new foundation type, is proposed by Tianjin University for applying to the specific load conditions. The diameter of the foundation is generally more than 30 m, and its embedment ratio is between 0.2 and 0.5. Compared with other traditional forms of ocean engineering foundation, there have been no standards and theories for bucket foundation designing currently. The vertical bearing capacity is an important basic indicator in the process of offshore wind turbine foundation designing, which determines the size of wind turbines and the cost of engineering. This paper proposes two failure mechanisms about vertical bearing capacity of bucket foundation through the experiment. The upper value of vertical bearing capacity of bucket foundation has been derived through the upper bound theorem of classical plasticity theory. Soil damaging rate is specified as a new empirical parameter in the formula. It is defined as the rate between the thickness of the soil which is broken inside the foundation and the radius of foundation, which indicates the range of soil failure. And the number range of soil damaging rate is obtained through the vertical bearing capacity experiments. Relationship between bearing capacity factor Nγ and friction angle also discussed under the specific soil damaging rates. These results are helpful in reducing the uncertainties related to the method of analysis in bearing capacity calculations, paving the way for more cost-effective foundation design.

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