DYNAMIC PERFORMANCE OF MUNICIPAL SLUDGE SOLIDIFIED SOIL UNDER FREEZE-THAW CYCLE

Sludge has the characteristics of high water content,poor mechanics and high pollutant content. Municipal sludge can be converted into sludge solidified soil by sludge solidification technology for safe treatment and rational utilization of municipal sludge. This paper aims to rationally and effectively utilize the mechanical properties of municipal sludge solidified soil. It studies the dynamic long-term mechanical indexes of municipal sludge solidified soil after different freezing temperatures and different freezing-thawing cycles. The cyclic dynamic load of municipal sludge solidified soil in natural environment is simulated using dynamic triaxial tester of different freezing temperatures and different freezing-thawing cycles. The experimental results show that the failure mode of sludge solidified soil presents brittle failure characteristics and has obvious shear surface. Under the coupling action of freezing at low temperature and multiple freeze-thaw cycles,with the decrease of freezing temperature and the increase of freeze-thaw cycles,the axial strain growth rate and final value of sludge solidified soil would also increase. By analyzing the dynamic stress-strain curves at different times,the relationship between the dynamic strength and the number of freeze-thaw cycles is obtained under different freeze-thaw temperature cycles,which provides a theoretical basis for the calculation of the dynamic strength of the sludge solidified soil. The change rule of static and dynamic long-term strength of sludge solidified soil is basically consistent with the increase of the number of freeze-thaw cycles. Under the same conditions,the static long-term strength of the sludge solidified soil is obviously greater than its dynamic long-term strength.