Abstract: Based on the application of gridiron cement-mixed piles and sand piles to protection of high-voltage cable channel in soft ground improved with vacuum preloading technique,protection project was analyzed.Some contrast were performed on protected and non-protected sections by vacuum preloading to observe surface deformation,deep lateral displacement and pore water pressure in stratum.It was shown that the protection project was effective and the high-voltage cable channel was safe.Variation of pore pressure water demonstrated that there was seepage through gridiron cement-mixed piles in deep soil.The change in effective stresses resulted from falling of pore water pressure and ground water seepage was the main factor inducing deformation of soft ground by vacuum preloading.