论文部分内容阅读
地基土质条件对建筑物震害的影响是很明显的,地基土的脉动观测是研究地基土质条件的重要手段之一。本文首先介绍了昆明的地形,地质构造和市区的地层概况,进而简述了地基土质条件与震害的关系,最后对昆明市九个点的地基土的脉动观测结果作了一些分析,根据脉动的周期分布得出:昆明盆地边缘靠山基岩出露地区、市区北部丘陵地带的园通山,五华山基岩出露地区、属Ⅰ类地基土。市区冲洪积地层上的地基土、脉动的平均周期和卓越周期分布在0.2—0.4秒之间,属Ⅱ类地基土。盆地近湖地区的湖相沉积地基土,脉动的平均周期和卓越周期分布在0.4震1秒之间,且地下水位又高,属Ⅲ类地基土。一般来说,Ⅲ类地基地上的震害是比较大的。为了防止建筑物地基土的自振周期和地震波周期相近而引起共振加大震害,在Ⅰ类地基土上最好不要建筑固有周期在0.1—0.2秒的结构物。在Ⅱ类地基土上避开固有周期在0.2—0.4秒的结构物,在Ⅲ类地基土上避开固有周期为0.4—1秒以上的高层建筑、高大的烟囱和跨度较大的厂房等。
The effect of foundation soil conditions on the seismic damage of buildings is obvious. The pulsation observation of foundation soil is one of the important methods to study the soil conditions of foundation. This paper first introduces the topography of Kunming, the geological structure and the general survey of the urban area, and then gives a brief description of the relationship between the soil conditions and the earthquake damage. Finally, it makes some analysis on the pulsation observation results of the nine soil foundation in Kunming. The periodic distribution of the pulsation results in the outcropping of the bedrock-bearing rocks on the edge of the Kunming Basin, the Yuantong Mountain in the hilly area in the northern part of the urban area, and the outcrop of the Wuhuashan bedrock. The urban area alluvial stratigraphy on the foundation soil, the average period of pulsation and excellent cycle distribution in 0.2-0.4 seconds, is a class II foundation soil. The lacustrine sedimentary foundation soil in the near lake area of the basin has an average period of pulsation and excellent period distribution between 0.4 second and 1 second with a high groundwater level, which belongs to the Ⅲ type of soil. In general, the damage on the foundation of type III foundation is relatively large. In order to prevent the natural period of building foundation soil and the seismic wave period similar to cause resonance and increase the damage, it is better not to construct the natural period of 0.1-0.2 seconds on the type I foundation soil. In the type Ⅱ foundation soil to avoid the inherent cycle of 0.2-0.4 seconds in the structure of the soil in the Ⅲ class to avoid the inherent cycle of 0.4-1 seconds above the high-rise buildings, tall chimneys and large span of the plant.