Dip‐adaptive singular‐value decomposition filtering for seismic reflection enhancement

We present a singular value decomposition (SVD) filtering method for the enhancement of coherent reflections and for attenuation of noise. The method is applied in two steps. First normal move‐out (NMO) correction is applied to shot or CMP records, with the purpose of flattening the reflections. We use a spatial SVD filter with a short sliding window to enhance coherent horizontal events. Then the data are sorted in common‐offset panels and the local dip is estimated for each panel. The next SVD filtering is performed on a small number of traces and a small number of time samples centred around the output sample position. Data in a local window are corrected for linear moveout corresponding to the dips before SVD. At the central time sample position, we sum over the dominant eigenimages of a few traces, corresponding to SVD dip filtering. We illustrate the method using land seismic data from the Tacutu basin, located in the north‐east of Brazil. The results show that the proposed method is effective and is able to reveal reflections masked by ground‐roll and other types of noise.     

喜河水电站坝址区缓倾角结构面综合分析研究

喜河水电站坝型为混凝土重力坝,重力坝对地基岩体的抗剪强度有较高的要求。前期勘查成果表明喜河水电站坝址区存在较多的缓倾角结构面,缓倾角结构面的存在是影响坝基抗滑稳定的关键,因此要对坝基作出抗滑稳定性评价。首先要研究坝址区缓倾角结构面的分布规律及连通情况,通过对坝址区缓倾角结构面的综合分析研究提出合理的坝基岩体的综合抗剪强度。     

水运工程测量状况及发展前瞻

对水运工程测量状况从理论发展和技术手段上进行了详细分析,对水运工程测量技术水平进行了评价,指出了水运工程测量行业的现存问题,并根据测绘技术手段的发展,针对水运工程测量的特点,对水运工程测量的发展方向进行了预测。