摘要
从地震的粘滑机制出发,本文建议了一种非均匀断裂模型,推导出峰值地面运动与非均匀断裂参数之间的一组关系式。根据峰值加速度和峰值速度资料,我们可以方便地估计震源中辐射峰值地面运动区域的半径r_i,应力降ΔS_2,平均滑动D_i。同时,也能估计出辐射峰值地面运动区域周围应力调整的最值ΔS_1。地震和矿山震动的峰值地面运动资料的分析表明,与人们的预料相同,一般有ΔS_2≥Δτ≥ΔS_1,这里Δτ是整个震源的平均应力降。所以,辐射峰值地面运动的区域往往是震源中的局部高应力降区。计算结果还表明ΔS_1可正可负,说明其周围区域的应力可能增强,也可能减小。 根据粘滑的实验室资料,本文建议的模型可以对峰值地面加速度的上界进行估计。对于张应力状态,a≤0.80g;对于压应力状态,a≤4.0g。这里,a是近源处地表面上记录到的峰值水平加速度的上界。对于走向滑动断层,a将介于0.80g和4.0之间。
The author develops a model of inhomogeneous faulting from stick-slip mechanism,and derives a number of relations between peak ground motion and faulting parameters of source. Small-scale parameters, such as the radius ri, the stress drop △S2 and the slip Di of the asperity surrounded by a previously faulted annular region, as well as the stress adjustment △S1 in the previously faulted region, can be estimated from these relations. The investigation for some earthquakes and mine tremors shows that △S2≥△τ≥△S1, where At is the average stress drop over the entire fault zone, therefore the region radiated peak ground motion is a local high stress drop zone in the source. In addition, the calculated results show that △S1 can not only be positive, but also negative. This fact indicate that the stress of the previously faulted region can not only decrease, but also increase.Upper bound on peak acceleration can be estimated from the laboratory data about stick-slip in terms of the present model. For extensional states of stress, a≤0.80g, and for compressional stress states,a<4.0g, where a now represents the maximum horizontal acceleration as recorded at the surface directly above the seismic source. For a perfect strike-slip,a is located in the interval (0,80g, 4,0g),
出处
《地震工程与工程振动》
CSCD
北大核心
1992年第1期7-17,共11页
Earthquake Engineering and Engineering Dynamics
基金
地震科学联合基金
