论文部分内容阅读
利用爆破震动作为震源,观测、分析兰州市皋兰县城附近一黄土沟谷斜坡体的地震动分布情况及其动应力响应特征,为斜坡地震地质灾害的易发性研究提供科学依据。试验分析表明:(1)斜坡体上的地震动最大幅值变化明显受地形条件控制,斜坡中上部强震观测点QZH14所处部位地势内凹,对地震波有汇聚作用,其水平分量PGA明显大于周边其他测点。(2)爆破地震动作用下河谷底部反应谱以单峰型为主,斜坡体上为双峰型,反映河谷底部与斜坡体不同结构地质体的地震动特征。(3)爆破试验场地同一位置处的地震动与其动应力响应具有很好的对应关系,地震动幅值大的部位土体的动力响应也较大;斜坡体不同埋深部位的土体动力响应并不一定表现出一致增大或减小的规律,受地形和岩土结构等影响可能存在显著差异。研究认为地震动幅值、频率特征、地震波的入射角度等因素通过影响斜坡体的地震动参数变化,进而影响地震地质灾害的发育程度。
By using blasting vibration as the source of earthquake, the distribution of ground motion and the dynamic stress response of a loess slope near Gaolan County in Lanzhou City are observed and analyzed, which provides a scientific basis for the research on the susceptibility to the earthquake and geological disasters in slope. Experimental analysis shows that: (1) The maximum amplitude change of ground motion on slope is obviously controlled by the terrain conditions. The site of QZH14 located at the middle and upper strong earthquake observation point is concave and has a convergence effect on seismic waves. The horizontal component PGA is obviously larger than Surrounding other measuring points. (2) The response spectrum at the bottom of the river valley under the action of blasting ground motion is mainly single peak type, bimodal type on the slope body, reflecting the ground motion characteristics of different structural geologic bodies at the bottom of the river valley and the slope. (3) There is a good correspondence between the ground motion at the same place in the blasting test site and its dynamic stress response, and the dynamic response of the soil at the site with large earthquake amplitude is also large. The dynamic response of the soil at different depths of the slope body May not necessarily show a law of uniform increase or decrease, which may be significantly affected by topography and geotechnical structures. It is considered that the amplitude of earthquake, the frequency characteristics and the angle of incidence of seismic waves and other factors affect the development degree of seismic geological disasters by affecting the variation of ground motion parameters of slope body.