Based on the analysis of the intensity properties of cement remolded loess,the authors come to a conclusion that its shear strength is influenced by such factors as its mixture ratio,water content,and maintenance time,hence the research is of great significance to its practical application.

Settlement characteristics of cement-soil pile composite fonndation is analyzed, according to foundation stiffness, replacement ratio, pile-soil modulus ratio, mixture ratio, the modulus ratio of substratum and reinforced area, considering the interaction between subgrade and foundation, using FEM software.

The optimum conditions were:feedstock preheating temperature 250℃,first and second riser outlet temperature 510,525℃ respectively,blending ratio of vacuum residue in feedstock about 35%,the mass fraction of discharging decanted oil 3%-4%,the recycling rude gasoline feeding above nozzle of recycling decanted oil,using LV-23 type FCC catalyst.