煤田陷落柱的地震响应特征通常以绕射波的形式表现，因此绕射波是识别和追踪煤田陷落 柱的有效波场。 为了有效利用绕射波准确预测煤田陷落柱，基于中值滤波理论，在借鉴频域带阻滤 波概念的基础上，开发出一种利用中值阻滤波分离地震绕射波的方法，并建立了一套有效的绕射波 成像处理流程。 1 地震绕射波利用的关键是如何完整地分离出绕射波，由于绕射波与反射波的时 距特征存在差异，基于统计特性的中值阻滤波存在分离绕射波与反射波的可能性;2 为了有效压 制强能量的反射波干扰，需要通过正常时差校正( NMO) 处理，目的是进一步加大反射波与绕射波 的横向相干性差异，然后再对不同地震道上相同采样时间的一维地震信号实施中值阻滤波分离绕 射波;3 为了确保绕射波完整提取，通过建立主波数带与地震道数的关系，定量确定中值阻滤波窗 口因子;4 利用叠前地震偏移成像方法分别对分离出来的绕射波场和全波场进行成像处理，然后 联合绕射波和全波场成像结果预测煤田陷落柱。 通过一个典型的煤田陷落柱模型验证了方法的正 确性，并进一步应用于山西 Z 煤田的陷落柱预测。 研究结果表明:本文方法能有效分离地震绕射 波，绕射波偏移成像结果明显优于传统反射波成像结果，能清晰揭示出陷落柱的棱廓、规模等信息， 可有效提高煤田陷落柱的识别精度。

The seismic response characteristics of collapsed columns are usually expressed in the form of diffraction， so diffractions are effective wave fields to identify and track collapsed columns. In order to effectively use the diffrac⁃ tion to accurately predict the collapse column in coal field， a method for separating seismic diffraction via median stop filter was developed based on the median filter theory and the idea of frequency domain band stop filter， and an effec⁃ tive diffraction imaging processing flow was established. 1 The key to the utilization of diffraction is how to completely separate diffraction waves. Due to the difference of time distance characteristics between diffraction and reflection， the median stop filter based on statistical characteristics has the possibility of separating diffraction and re⁃ flection. 2 To effectively suppress the reflection， it is necessary to increase the transverse coherence difference be⁃ tween reflection and diffraction through NMO， and then implement median stop filtering to separate the diffraction for the one⁃dimensional seismic signal with the same sampling time on different seismic channels. 3 To ensure the complete extraction of diffraction， the window factor of the median stop filter is determined quantitatively by establishing the relationship between the main wavenumber band and the number of seismic channels. 4 The separa⁃ ted diffraction and full wave field are imaged by pre⁃stack seismic migration imaging method， and then the coalfield collapse column will be predicted by combining the diffraction and full wave field imaging results. The cor⁃ rectness of the method was verified by a typical coalfield collapse column model， and it was further applied to the pre⁃ diction of collapse column in Shanxi Z coalfield. The results show that the diffraction migration imaging results are ob⁃ viously better than that of the traditional reflection. The diffraction migration imaging can clearly reveal the edge pro⁃ file， scale and other information of the collapse column， and can effectively improve the identification accuracy of the coalfield collapse column.