A field experimental study of sludge vacuum preloading based on the temperature increasing heating technology

Abstract

Temperature increasing heating combined with vacuum preloading is a new sludge dewatering and consolidation technology, and relevant field experimental research has not been carried out. The Baiyangdian sediments are taken as the research object in this study, an intermittent temperature mass phase change vaporizer combined with vacuum preloading is used to conduct field experimental research on sludge dewatering and consolidation. The technical principle of temperature increasing heating combined with vacuum preloading is expounded from the aspects of thermodynamics and osmotic consolidation theory, and the treatment effect is compared with conventional vacuum preloading. The results show that the technology of warming and heating combined with vacuum preloading can greatly improve the consolidation settlement of sediments. The volume compression rate is about 3 times that of the conventional vacuum preloading, the water content of the sediments is 34.59%, which is 18.6% lower than that of the conventional vacuum preloading, the strength of vane is about 2 times higher, and the degree of consolidation after 61 d of treatment is 83.3% to 85.4%. However, there is uneven settlement on the surface of sediments after treatment, showing that the farther away from the warming device on the plane, the smaller the settlement. According to the effective stress theory of saturated soil, the closer to the temperature increasing device, the faster the pore water pressure dissipates. When the temperature increasing heating stops, the pore water pressure has an obvious rebound phenomenon. The closer to the temperature increasing device, the greater the rebound, which is mainly related to the buried depth, loading time and temperature loading mode of the temperature increasing device. At the same time, according to the variation law of sediment moisture content and settlement, it is preliminarily determined that the effective radius of the temperature increasing device is 2 m to 3 m. The results may provide technical guidance for the engineering application of this technology.

Keywords

• warming heating
• vacuum preloading
• silt
• field test