<p>Prefabricated horizontal drains (PHD) assisted with vacuum preloading are increasingly used for the improvement of soft soils, but the process remains time-consuming, non-uniform, and results in relatively low shear strength. Heating by solar energy has been suggested as a potential approach to enhance consolidation efficiency. In this study, laboratory physical model tests were conducted on waste slurry with ultra-high water content using grid PHDs-vacuum preloading at 20, 40, and 60&#xa0;°C. During the tests, temperature distribution, pore water pressure, surface settlement, water content, and void ratio were continuously monitored. After the consolidation, undrained shear strength and one-dimensional compressibility of the treated soils were evaluated. The results indicate that increasing temperature accelerates pore water pressure dissipation and improves vacuum transmission to higher layers, leading to higher effective stress and larger final settlement. Elevated temperatures also reduce vertical non-uniformity of consolidation, reflected by more uniform vertical water content and void ratio profile. The undrained shear strength of the slurry increases markedly with temperature, while the compression index decreases significantly for treated soils from drainage boundary 5 cm at elevated temperatures. In addition, particle migration was observed during consolidation. Supplementary model tests indicate that elevated temperature promotes the transport of clay particles with discharged water and the downward accumulation of sand and silt particles near the drains, resulting in noticeable particle redistribution within the soil. These observations suggest that the performance of PHD–vacuum preloading under elevated temperatures is influenced by both enhanced drainage and temperature-induced particle migration, which together modify the soil fabric and improve consolidation efficiency.</p>