Model Tests of Soil Reinforcement Inside the Bucket Foundation with Vacuum Electroosmosis Method
Abstract
:1. Introduction
2. Model Tests
2.1. Soil Preparation and Parameters
2.2. Test Setup
2.3. Test Procedure
3. Results and Discussion
3.1. Effects of Foundation Settlement and Displacement during Soil Improvement
3.2. Effect of Pore Water Pressure during Soil Reinforcement
3.3. Effects of Shear Strength and Soil Moisture Content before and after Soil Reinforcement
4. Bucket Foundation Bearing Capacity before and after Soil Reinforcement
4.1. Influence of Soil Reinforcement on Bucket Foundation Vertical Bearing Capacity
4.2. Influence of Soil Reinforcement on Bucket Foundation Horizontal Bearing Capacity
4.3. Influence of Soil Reinforcement on Rotation Centers
5. Conclusions
- (1)
- The vacuum electroosmosis reinforcement significantly improves soil strength inside the bucket foundation when using the bucket wall as the anode, and undrained shear strength increases with increasing the voltage. The undrained shear strength of the soil applied the voltage of 20 V is 3–4.5 times that applied the voltage of 3.75 V in this study. Furthermore, a higher driving voltage can improve the uniformity of soil reinforcement in the vertical direction. The vertical bearing stiffness of the reinforced foundation during soil compression is 3.25 times the bearing stiffness of an unreinforced foundation.
- (2)
- Using the bucket wall as the cathode causes a percolation passage along the bucket wall to form, which decreases the reinforcement effect. The strengthening effect of the conversion electrode method was weaker than using the bucket wall as the anode. In addition, increased internal vertical drainage channel during the reinforcement can effectively improve vacuum pressure transmission inside the soil, thereby improving the reinforcement.
- (3)
- The horizontal and vertical bearing capacity of bucket foundation can be significantly increased through vacuum electroosmosis reinforcement. General shear failure of the bucket foundation occurs under vertical load. The vertical bearing stiffness of the reinforced foundation during soil compression is 3.25 times the bearing stiffness of an unreinforced foundation, and the vertical bearing capacity of the foundation increased by 2.1 times after soil reinforcement.
- (4)
- The bucket foundation undergoes forward destructive failure when subjected to horizontal load. In the elastic stage, the horizontal resistance of the reinforced foundation is 8.3 times that of the unreinforced foundation, and the horizontal bearing capacity increased by 2.9 times. Soil reinforcement improves the stiffness of the soil and the passive earth pressure; thus, the height of the rotation center is significantly reduced after soil reinforcement.
Author Contributions
Funding
Conflicts of Interest
References
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Soil Type | Moisture Content w (%) | Plastic Limit wp (%) | Liquidity Index IL (%) | Plasticity Index IP | Shear Strength Su (kPa) | Permeability Coefficient k (cm·s−1) | Unit Weight γ (kN·m−3) | Coefficient of Compressibility a (MPa−1) |
---|---|---|---|---|---|---|---|---|
Clay | 50 | 22 | 37 | 15 | 1~2 | 6.7 × 10−6 | 17.2 | 0.91 |
Test Nos. | Vacuum Loading (kPa) | Voltage (V) | Reinforcement Time (h) | Bucket Wall Electrode | Copper Rod Electrode |
---|---|---|---|---|---|
T1 | 60 | 0 | 70 | —— | No |
T2 | 60 | 0 | 70 | —— | Yes |
T3 | 60 | 3.75 | 70 | Anode | Yes |
T4 | 60 | 3.75 | 27 | Cathode | Yes |
T5 | 60 | 3.75 | 70 | A ↔ C * | Yes |
T6 | 60 | 20 | 70 | Anode | Yes |
TV1 | —— | —— | —— | —— | —— |
TH1 | —— | —— | —— | —— | —— |
TV2 | 60 | 20 | 70 | Anode | Yes |
TH2 | 60 | 20 | 70 | Anode | Yes |
Test Nos | 2.5 h | 10 h | 50 h | |||
---|---|---|---|---|---|---|
Settlement (mm) | Water Discharge (kg) | Settlement (mm) | Water Discharge (kg) | Settlement (mm) | Water Discharge (kg) | |
T1 | 2.942 | 0.388 | 6.941 | 0.782 | 15.659 | 1.786 |
T2 | 5.471 | 0.454 | 10.506 | 0.922 | 17.522 | 2.054 |
T3 | 8.614 | 0.796 | 14.133 | 1.339 | 26.189 * | 3.143 * |
T4 | 13.599 | 0.924 | 18.105 | 1.410 | - | - |
T5 | 9.150 | 0.471 | 13.247 | 0.947 | 21.813 | 2.158 |
T6 | 11.864 | 0.706 | 20.740 | 1.411 | 31.412 | 5.646 |
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Zhai, H.; Ding, H.; Zhang, P.; Le, C. Model Tests of Soil Reinforcement Inside the Bucket Foundation with Vacuum Electroosmosis Method. Appl. Sci. 2019, 9, 3778. https://doi.org/10.3390/app9183778
Zhai H, Ding H, Zhang P, Le C. Model Tests of Soil Reinforcement Inside the Bucket Foundation with Vacuum Electroosmosis Method. Applied Sciences. 2019; 9(18):3778. https://doi.org/10.3390/app9183778
Chicago/Turabian StyleZhai, Hanbo, Hongyan Ding, Puyang Zhang, and Conghuan Le. 2019. "Model Tests of Soil Reinforcement Inside the Bucket Foundation with Vacuum Electroosmosis Method" Applied Sciences 9, no. 18: 3778. https://doi.org/10.3390/app9183778
APA StyleZhai, H., Ding, H., Zhang, P., & Le, C. (2019). Model Tests of Soil Reinforcement Inside the Bucket Foundation with Vacuum Electroosmosis Method. Applied Sciences, 9(18), 3778. https://doi.org/10.3390/app9183778