Tunnel advanced detection speed modeling method based on reflected signal

Abstract

The invention discloses a tunnel advanced detection speed modeling method based on a reflected signal, and the method comprises the steps: obtaining X and Z component seismic signals through a conventional linear observation system; determining an i-th X and Z component reflection in-phase axes according to the negative speed features of a seismic wave, and selecting the X and Z component reflection wave groups of a seismic channel with the maximum offset; selecting the maximum amplitude time t1 of a negative phase from the reflection wave groups, and calculating the main polarization direction theta1 of t1; selecting a time window with the (t1+ / -1) cycle length from a seismic record; carrying out the shifting at a supposed speed Vi based on a seismic signal of the selected time window; carrying out comparison, and obtaining V1max of the maximum offset energy; calculating L1 (=V1max*t1), sequentially building an i-th speed through the main polarization direction theta1, V1max and L1, and building a final speed model. The method does not need to drill a hole for increasing a lateral offset, and saves manpower and time resources. Through the extraction of the effective reflection wave groups and the limiting of the range of the time window, the method effectively avoids the mutual interference of front and rear abnormal interface energy groups, and guarantees the accuracy of speed modeling.

Description

technical field [0001] The invention relates to a modeling method, in particular to a roadway advanced detection speed modeling method based on reflected signals, and belongs to the technical field of coal mine safety production. Background technique [0002] According to incomplete statistics, among the frequent coal mine safety accidents, more than 85% occurred in the roadway excavation process. Reflected wave seismic advanced detection is a fast and efficient roadway advanced detection technology. It uses the kinematics and dynamics characteristics of reflected waves when propagating in uneven geological bodies to predict and forecast the geological conditions ahead of roadway excavation, thereby guiding roadway safety. excavation. In the process of processing the advance detection data of the roadway, it is of great significance to construct the velocity model closest to the actual medium to obtain the dynamic parameters of the coal and rock mass, because the abnormal p...

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Problems solved by technology

[0004] However, the above two methods have their disadvantages: replacing the front surrounding rock velocity with the sidewall surrounding rock velocity is very imprecise in both practical application and theoretical analysis, which is one of the reasons why advanced detection often misreports; and Establishing a velocity model by increasing the lateral offset requires drilling to provide a larger lateral offset, which consumes a lot of manpower, material and time resources

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