The storage capacity of sludge landfills in some places in China is seriously inadequate. To restore the storage capacity and reinforce the pit body

the experiment of vacuum preloading drainage reinforcement of landfill sludge conditioned by FeCl3 was carried out. The accumulative drainage volume and accumulative settlement of the sludge were recorded

and moisture content test

vane shear test

and mercury intrusion porosimetry were carried out after the experiment. Results show that the effect of deep dewatering of the sludge by vacuum preloading method was limited. After chemical conditioning

the dewatering performance was improved

the drainage rate and drainage volume were increased

and the average moisture content was reduced from 75.8% to 66.6%. After vacuum preloading

the distributions of moisture content and shear strength were uneven

and the closer it was to the drainage board

the greater the change was. The moisture content increased gradually along the radial and depth directions

while the shear strength gradually decreased. The pore diameter of the conditioned sludge was mainly distributed in the range of 200-100 000 nm. The proportion of small holes was the highest

followed by that of the middle holes

and the closer it was to the drainage board

the more the large holes were

the fewer the micropores were. The moisture content and volume of the sludge decreased by 9.2% and 28.8% respectively

and the strength increased by ten times

indicating that the proposed method had better treatment effect. The dewatering and volume reduction effect can be further improved by optimizing agent combination and vacuum preloading process parameters.