7.3.3 The parameters loss rate
From Fig. 18, it can be seen that different experiments might have different effects on the deterioration to samples. The effect of acid rain cycle on the parameters loss rate of samples is greater than that of samples depending on the dry-wet cycle and freeze-thaw cycle, and the greatest in pH=2.6. The samples are also deteriorated by the dry-wet cycle and freeze-thaw cycle as well. Among them, the parameters loss rate of saturated group is higher than that of samples after the dry-wet cycle, and the lowest in dry group. The parameters loss rate of samples follows this order: pH=2.6>pH=4.1>pH=5.6>saturated group>dry-wet cycle>dry group. This indicates that the samples are more susceptive to the effects of acid rain cycle. Furthermore, the drop in parameters of LA samples is larger than that of LB samples in different experiments, signifying that the sandstone of bedding development is among the first to be affected by weathering. The results suggest that the weathering degree of the upper part of Niche of Sakyamuni Entering Nirvana is more serious than that of the middle part accompanied by a large amount of granular disintegration.