RELATIVE WEATHERING RATES OF SIX DIFFERENT LITHOLOGICAL ROCKS IN TONGXIAN GATE OF QUZHOU ANCIENT CITY WALL

Long-term weathering of rock will cause the rock surface recession, which will cause irreparable damage to stone cultural relics. Those precious stone cultural relics are being protected for a long time. But the result is not optimistic. In theory, in order to protect them well, it is important to study the relationship between the rock surface recession and the relative weathering rate with the different lithology in the same environment. The paper is intended to study the surface recession of different lithology rock blocks and their weathering rate. The rock blocks are part of the Tongxian gate of Quzhou ancient walls of national key cultural relics protection sites. An especially designed movable instrument is used. By analyzing the measured data, the weathering rates of different rocks are attained so as to provide an actual basis for the stone cultural relics and the development of relevant protective measures. The measurement results are from tufa, sandstone, conglomerate, pebbly sandstone and siltstone. Their weathering rates with respect to limestone are 0.005～0.059, 0.032～0.097, 0.004～0.058, 0.021～0.033 and 0.015mm a-1,respectively. The results also show that under the same weathering environment, different weathering rates of rock block order from large to small is VsandstoneVtufaVpebblysandstoneVconglomerateVsiltstoneVlimestone,which means that the rock weathering resistance from strong to weak is:VlimestoneVsiltstoneVconglomerateVpebblysandstoneVtufaVsandstone.This study can provide an important data basis for the long-term protection of stone relics and formulate relevant protective measures.