基于地震映像的河湖水下抛石精准识别方法

基于水下抛石与围岩的波阻抗差异,应用地震波数值模拟软件Tesseral 2-D建立含有水、抛石、填土及基岩的水下抛石模型并对其进行正演模拟。分析了不同震源子波频率和偏移距时的地震响应特征,最终确定震源子波频率为600 Hz,偏移距为5 m的地震数据采集参数。采用一种新型的"轻型气压式浅水域全自动触发器"震源设备对龙河口水库水下抛石进行实际探测。实践表明,地震映像能够识别抛石层的分布范围和厚度,与实际情况吻合的较好。这为利用地震映像法实现对浅水域水下目标体的精确识别提供了重要的理论和实践依据。

Method of seismic imaging-based accurate recognition of underwater riprap of rivers and lakes

Based on the discrepancy of wave impedances between underwater riprap and surrounding rock，an underwater riprap model that contains water，riprap，earth fill and foundation rock is established with the seismic wave simulation software Tesseral 2-D，and then the relevant forward modelling is made. The seismic response features during various wavelet frequencies and offsets of seismic source are analyzed，thus the the data acquisition parameters，i. e. the seismic source wavelet frequency of 600Hz and the offset of 5m，are determined. With a new type of seismic source equipment——light pressure type shallow water full-automatic trigger device，an actual exploration is made on the underwater riprap of Longhekou Reservoir. The practice shows that the distribution range and thickness of the riprap layer can be recognized by seismic imaging，from which a better coincidence with the actual condition is realized. It provides an important theoretical and practical basis for realizing the accurate recognition of the underwater target in shallow water with the seismic imaging method.