Experimental study on dredged slurry treatment with straw as horizonal drains by vacuum preloading

This paper presents a novel method of treating high water content dredged slurry by vacuum pre-pressure using woven rice straw as horizontal drainage boards (SHDs). This not only helps to avoid the impact of plastic drainage boards on the environment, but also helps to utilize agricultural related waste. The study aimed to investigate the effect of SHDs degradation on the vacuum transfer within the horizontal drainage boards and the consolidation characteristics of dredged slurry. Indoor vacuum preloading model tests were conducted to investigate soil settlement, straw degradation, vacuum variation and water content distribution within the drainage board. The results show that SHDs can significantly improve the consolidation of dredged slurry. The closer the straw is to the interface between the drainage board and the vacuum pipe, the greater the degree of degradation. The water content was distributed with depth in an oblique “z” shape, while a point with higher water content existed at 1/3 of the soil above the drainage boards. In addition, the low water content zone around the drainage board shows an elliptical shape due to the influence of gravity. These research results have some reference value for the ecological treatment of dredged slurry and straw.