爆破场地黄土震陷空间分布特征研究
Distribution characteristics of seismic subsidence of in-test field by explosion
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摘要: 黄土震陷是广大黄土地区在进行工程建设时避免不了的一种主要地震灾害。许多年来,黄土震陷研究是以室内试验为主要手段,天然地震黄土震陷现象的例证与现场试验的研究较为罕见。在典型震陷性黄土场地通过爆破方法模拟实际地震动的现场试验能够直观地了解黄土震陷发生的真实过程和分布特征和影响因素。试验结果表明,较强的地震动可以诱发黄土震陷的发生;场地内黄土震陷的最大量值可达33 mm,最小值约为13 mm;通过分析场地内黄土震陷分布特征和地震动强度分布特征可知,地震动强度与频谱H/V值是影响黄土震陷的决定性因素,地形也对震陷分布具有一定的影响;因为离爆破点较近,场地下部土层沉降贡献率大于上部土层。Abstract: The seismic subsidence of loess is a main kind of earthquake disaster in a large loess region, and it cannot be avoided during project construction. It has been investigated for many years mainly by indoor experiment, while it is rare that it is found during actual earthquakes or investigated by field tests. The seismic subsidence of loess can be really seen by blast instead of actual ground motion in typical loess field. So distribution characteristics can be found and factors of the seismic subsidence of loess can be analyzed. The experimental results show that the strong ground motion can cause seismic subsidence of loess. The maximum of loess subsidence is 33 mm and the minimum is 13 mm in test field. It is discovered that the settlement distribution coincides well with the strength of ground motion and spectral characteristics (value of H/V) in the loess field and is partly controlled by terrain. The seismic subsidence of upper loess layers is less than that of the lower ones in the field tests due to the closer distance between the lower layers and explosion shots.