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Importance of Verticality of PVD in Consolidation Settlement of Prefabricated Vertical Drain-Improved Soft Soils
This paper shows how vital the verticality of a PVD is. In this study, a physical model of measures 452 mm diameter and 600 mm high is used. The paste of silty-clay soil of medium plasticity is prepared at water content below its liquid limit. In the first case, a PVD is centrally placed before pouring the paste. In other words, a mandrel is not used in this study to eliminate its disturbance on soil mass. Soil bed with PVD is, after that, prepared in three stages. A sand layer is then placed on the top surface. Above the sand layer, the seating plate through which vertical pressure is applied is placed. On this plate, an incremental vertical pressure of 10 kPa is applied at an interval of 7 days up to 63 days, and accordingly, consolidation settlements are recorded. In the second case, a PVD is placed in such a way that it makes an angle (θ) of 4°45′ (tilted) at the bottom center of the bed, i.e., the PVD is dislocated at the upper portion by 5 cm. The same test procedure is followed here also. From the test results, it is observed that the latter case exhibits lesser settlement results as compared to the first case. It may be attributed to the clogging and buckling that occurred at the upper portion of the PVD due to the non-uniform ordination of vertical pressure between the PVD faces. Therefore, it may be concluded that maintenance of its verticality should also be taken care of to achieve a larger settlement during PVD installation.
Importance of Verticality of PVD in Consolidation Settlement of Prefabricated Vertical Drain-Improved Soft Soils
This paper shows how vital the verticality of a PVD is. In this study, a physical model of measures 452 mm diameter and 600 mm high is used. The paste of silty-clay soil of medium plasticity is prepared at water content below its liquid limit. In the first case, a PVD is centrally placed before pouring the paste. In other words, a mandrel is not used in this study to eliminate its disturbance on soil mass. Soil bed with PVD is, after that, prepared in three stages. A sand layer is then placed on the top surface. Above the sand layer, the seating plate through which vertical pressure is applied is placed. On this plate, an incremental vertical pressure of 10 kPa is applied at an interval of 7 days up to 63 days, and accordingly, consolidation settlements are recorded. In the second case, a PVD is placed in such a way that it makes an angle (θ) of 4°45′ (tilted) at the bottom center of the bed, i.e., the PVD is dislocated at the upper portion by 5 cm. The same test procedure is followed here also. From the test results, it is observed that the latter case exhibits lesser settlement results as compared to the first case. It may be attributed to the clogging and buckling that occurred at the upper portion of the PVD due to the non-uniform ordination of vertical pressure between the PVD faces. Therefore, it may be concluded that maintenance of its verticality should also be taken care of to achieve a larger settlement during PVD installation.
Importance of Verticality of PVD in Consolidation Settlement of Prefabricated Vertical Drain-Improved Soft Soils
Lecture Notes in Civil Engineering
Satyanarayana Reddy, C. N. V. (editor) / Saride, Sireesh (editor) / Krishna, A. Murali (editor) / Reang, Rai Bahadur (author) / Pal, Sujit Kumar (author) / Paul, Sanjay (author)
2021-07-28
8 pages
Article/Chapter (Book)
Electronic Resource
English
Radial consolidation of prefabricated vertical drain-reinforced soft clays under cyclic loading
| Elsevier | 2022