关于大理崇圣寺三塔中南、北小塔的倾斜原因一直有多种说法。在现场详细工程地质调查和室内试验基础上,结合区域地质与历史文献资料,对可能导致倾斜的地基不均匀性、地震作用进行研究后提出:由地基不均匀性形成的倾斜不应占主体,地震作用应是塔体出现倾斜的主要因素。地震导致的塔体顶部鞭梢效应非常明显,这与塔顶在历史上多次震坏事实相符;塔体下部压应力波动幅度大,但相对砖砌体强度来说有一定安全余地;而在高强度地震作用下,中部出现拉应力,对塔体结构破坏明显。而塔体下相对软弱的粉质黏土层在减缓地震波向上传播、减少塔体的动荷载作用上有明显效果。
There are some different explanations for the inclination origin of the south and north pagodas of the Three Pagodas in the Chongsheng Temple,Dali.Based on detailed site engineering geological survey and laboratory tests,combining the regional geological background and historical literatures analysis,it is presented that the main reason for the inclination of the two towers is earthquake rather than the nonuniformity of ground soils according to foundation settlement calculation and seismic simulation.The whipping effect derived from seismic action of the pagodas is significant which has caused several times top destruction in history.The vertical compressive forces at bottom layer fluctuate greatly during earthquake but it is safe comparing with the ultimate strengthen of brick masonry.Tension forces take place obviously at the middle part which cause fractures in case of high seismic magnitude.It is considerably reduced by the silt clay under the pagodas foundation that the propagation of earthquake wave from ground and the effect of the seismic vibration.