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Preloading with wick drains
Published in Jay Ameratunga, Sivakugan Nagaratnam, M. Das Braja, Soft Clay Engineering and Ground Improvement, 2021
Wick drains are generally flat, about 100 mm wide, and about 2 to 5 mm in thickness (see a typical wick drain in Figure 9.1). It has a core wrapped in a separation geotextile. The core allows the water to flow to the surface and the geotextile functions as a filter to ensure fine particles do not block the movement of water from the surrounding soil. Different types of core are available, and some are shown in Figure 9.1. There are circular types of wick drains too, generally the diameter varying from 35 mm to 50 mm, which are mostly used in vacuum consolidation applications. The wick drains allow the pore water to flow laterally for short distances to the closest wick drain rather than travel vertically over a long distance, thereby reducing the consolidation time significantly.
Effects of frequency and confining pressure on consolidation drainage behavior of soft marine clays
Published in Marine Georesources & Geotechnology, 2019
Yong-Hong Miao, Fan-Bo Zhou, Jie Yin, Yan-Chang Sun, Rui-Bing Li, Jian-Fei Lu
Figure 11 shows the relations between v and f for specimens at different σ'3. It indicates that frequency has a significant influence on the drainage behavior of soft soils. The variation trends of v with f are similar for specimens at various σ'3. v initially increases with the increasing f and then decreases when f exceeds 1 Hz for specimen at any σ'3. Besides, the variation of v with f at lower σ'3 lies above the specimen with higher σ'3. This is caused by the different water contents of specimens consolidated under σ'3. Moreover, specimens at f = 1 Hz show the largest magnitude of drainage volume due to resonant effect. We can find out that drainage volume for specimens at frequency 1 Hz increases by approximately 100% on average with respect to specimens under static loads, which proves that using dynamic vibration loading plus wick drain can present a good drainage performance to improve the soft clay foundation. Therefore, vibration load with frequency of 1 Hz plus wick drains are recommended in the practice of the soft soil improvement engineering.