Detection method for predicting cave of shallow portion via surface wave spectrum disturbance

Abstract

The invention discloses a detection method for predicting a cave of a shallow portion via surface wave spectrum disturbance. The detection method comprises that S1) one measuring line is arranged overa suspected cave area underground; S2) a vibration response signal of a measuring point of the measuring line is recorded; S3) the measuring line is deflected for certain angle, the step S2) is repeated, and the measuring line is continued to be deflected till the suspected cave area is covered completely; S4) cylindrical geometric attenuation correction is carried out all vibration response signals, and an offset-wavelength domain amplitude spectrum cloud atlas of different measuring lines of the suspected cavity area is obtained via a series of transformation; S5) a reference measuring lineis arranged in an area free of cave influence, vibration responses signals of different measuring points of the reference line are recorded, and an offset-wavelength domain amplitude spectrum cloud atlas of the reference line is obtained; and S6) the offset-wavelength domain amplitude spectrum cloud atlas of the measuring lines of the suspected cavity area is compared with that of the reference line, and the buried depth and position of the cave are predicted from the wavelength and offset corresponding to the spectrum disturbance characteristic of the suspected area. Thus, the near-surface cave detection problem can be solved effectively.

Description

technical field [0001] The invention specifically relates to a detection method for predicting shallow caves by using surface wave spectrum disturbance, which is suitable for geotechnical engineering or engineering geophysical exploration, and can also be used for the analysis of scattered wave propagation characteristics. Background technique [0002] In the construction of urban subways in limestone areas, because the buried depth of subways is often located in the distribution area of ​​limestone, the groundwater level in the shallow part of limestone varies greatly, and it is an area where karst caves are strongly developed. Karst caves can easily lead to accidents such as water inrush, mud inrush, ground subsidence, buried construction machinery and equipment, and casualties during construction. [0003] At present, the detection of underground karst caves often adopts drilling plus ground geophysical methods, such as geological radar plus high-density electrical method...

AI Technical Summary

Problems solved by technology

These geophysical methods have certain requirements on site environmental conditions and geological conditions. For example, electromagnetic waves attenuate quickly in soft or clay media, and the energy is very weak when they reach karst areas. It is difficult to identify reflected electromagnetic waves, and they are susceptible to various electromagnetic waves in complex environments. interference

Another example is that the electric method is easily affected by the dryness of the soil layer, the groundwater level, and the complex environment of the electric field at the test site.

It can be seen that the effects of these geophysical methods are often not ideal.

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