In this study

the nano-SiO2 (NS)and lime were used to solidify the coastal petroleum-contaminated soil. The effects of nano-SiO2 and lime on the solidification of coastal petroleum-contaminated soil(PCS) were studied through Atterberg limits tests

unconfined compressive strength tests and pH tests. The microstructure and mineral composition of typical modified petroleum-contaminated soil were analyzed by scanning electron microscopy and X-ray diffraction tests. The results indicate that the unconfined compressive strength of petroleum-contaminated soil with 5% petroleum content modified by NS-lime increases significantly. By adding 1% or 2% NS to the 3% lime-modified petroleum-contaminated soil

the 7-day saturated unconfined compressive strength of lime-modified petroleum-contaminated soil reaches 421 kPa and 727 kPa

respectively

more than 3 times and 5 times of that without NS. Meanwhile

adding NS reduces the pH of lime-modified petroleum-contaminated soil and the harm of lime to the environment. Furthermore

the scanning electron microscope test and X-ray diffraction test also prove that

compared with adding lime alone

when NS and lime are combined

the NS accelerates the hydration reaction of lime

promotes the formation of hydrated calcium silicate

and greatly improves the strength of coastal petroleum-contaminated soil.