[0041] The present invention will be further described in detail below in conjunction with the drawings and specific embodiments:
[0042] An urban underground pipe gallery detection method, such as Figure 1~5 As shown, it includes the following steps:
[0043] Step 1: According to the existing urban underground pipe gallery information, determine the direction of the urban underground pipe gallery to be detected, and evenly arrange multiple seismic wave acquisition device groups along the pipe gallery on the ground above the area to be detected of the urban underground pipe gallery. The setting position of each seismic wave acquisition device group is used as an acquisition area. The multiple seismic wave acquisition devices in each seismic wave acquisition device group are evenly arranged on the ground along the vertical direction of the pipe gallery. Each seismic wave acquisition device in the seismic wave acquisition device group collects The device is a sampling point in the collection area;
[0044] Step 2: Turn on the seismic wave acquisition device, and collect the seismic wave signals received by the seismic wave acquisition device group at each acquisition point in each acquisition area;
[0045] Step 3: Use the seismic wave signals of each acquisition point in each acquisition area to perform cross-correlation calculations, and calculate the seismic cross-correlation function between the most lateral acquisition point and the nth acquisition point in each acquisition area (equivalent to acquiring at the most lateral A seismic source is arranged in the device, and receivers are arranged in other acquisition devices to improve the accuracy of subsequent calculations. The specific formula is as follows:
[0046]
[0047] Among them, A 1 (t) represents the seismic wave signal of the most lateral acquisition point, A n (t) represents the seismic wave signal of the nth acquisition point, n is counted from the second acquisition point outside the most lateral acquisition point, and N is A 1 (t) and A n (t) The sum of the number of discrete data points of two seismic wave signals, m represents the variable, Indicates that m is taken from 1 to N-1 in the formula, and then summed, t represents the time, the seismic wave signal is a discrete signal, A 1 (m) represents the value of the m-th discrete point of the seismic wave signal at the most lateral acquisition point, A n (m+t) represents the value of the m+t discrete point of the seismic wave signal at the nth acquisition point;
[0048] Step 4: Use the seismic wave cross-correlation function obtained in step 3 to calculate the corresponding empirical Green's function (the real Green's function is difficult to obtain directly, here you can use the empirical Green's function to replace the real Green's function for calculation and processing), the specific operations are as follows :
[0049] The seismic wave cross-correlation function A between a most lateral acquisition point and the nth acquisition point in each acquisition area 1n (t), empirical Green's function And the real Green function G 1n The relationship between (t) is expressed as:
[0050]
[0051] Among them, Indicates the empirical Green's function when the geophone at the n-th collection point receives the signal as the seismic source, G 1n (t) represents the true Green's function when the geophone at the most lateral collection point is used as the seismic source and the geophone at the nth collection point receives the signal, Indicates the empirical Green's function when the detector at the nth acquisition point is used as the seismic source, and the detector at the most lateral acquisition point receives the signal, G n1 (t) represents the true Green's function when the detector at the nth acquisition point is used as the seismic source and the detector at the most lateral acquisition point receives the signal;
[0052] The empirical Green's function can be obtained by the time differentiation of the seismic cross-correlation function;
[0053]
[0054] A n1 (-t) represents the seismic wave cross-correlation function between the nth acquisition point and one of the most lateral acquisition points in each acquisition area;
[0055]
[0056] A n (m) represents the value of the m-th discrete point of the seismic wave signal at the n-th acquisition point, A 1 (m+t) represents the value of the m+t discrete point of the seismic wave signal of a most lateral acquisition point;
[0057] Step 5: Use the empirical Green's function obtained in Step 4 to extract the surface wave dispersion curve. The operation is as follows:
[0058] The result obtained in step 4 Combine it into:
[0059]
[0060] And Perform a two-dimensional Fourier transform to obtain a frequency wavenumber spectrum F(f,k), where f represents frequency and k represents wavenumber;
[0061] According to the definition of wave number
[0062]
[0063] Where v s Is the transverse wave velocity;
[0064] Transform the frequency wave number domain record to the frequency wave speed domain: use the frequency wave number domain record:
[0065]
[0066] Resample (i.e. by formula Convert the frequency wave number domain to the frequency wave speed domain) to obtain the frequency wave speed spectrum. At any frequency in the frequency wave speed domain, from the extreme point obtained from the frequency wave speed spectrum, the corresponding phase speed value of the frequency can be obtained, thereby obtaining the surface Dispersion curve of wave recording;
[0067] Step 6: Because there is a pipe gallery underground, the dispersion curve obtained in step 5 has multi-mode characteristics. Decompose the fundamental mode and higher-order mode of the dispersion curve to obtain the fundamental mode part and each higher-order mode part of the dispersion curve;
[0068] Step 7: Due to the characteristics of surface waves, the velocities of waves of different wavelengths correspond to the velocities of the corresponding depth positions underground, so based on the several sets of dispersion curves obtained in step 6, the corresponding velocity profile of the area to be detected can be obtained;
[0069] Step 8: Detect the area to be detected in the urban underground pipe gallery, and compare and analyze with the sections obtained in step 7, discard inconsistent sections, leave consistent sections, and find out from the sections Underground wave speed abnormal area, the underground wave speed abnormal area corresponds to the location of the underground pipe gallery.
[0070] In the step 8, the area to be detected of the urban underground pipe gallery is detected by the geological radar or the transient Rayleigh surface wave method.
[0071] In step 8, the anomalous area of underground wave speed indicates an area where the wave speed is higher than the surrounding wave speed.
[0072] The most lateral collection point is the leftmost collection point or the rightmost collection point.
[0073] The distance between two adjacent seismic wave acquisition device groups ranges from 50 to 200 meters (in the straight-line traveling area, there are two accurate end points within this distance, and the specific location of the pipe gallery can be determined).
[0074] The distance between two adjacent seismic wave acquisition devices in each seismic wave acquisition device group ranges from 0.15 to 2 meters (the smaller the distance, the higher the measurement accuracy, but the use cost and efficiency issues need to be considered).
[0075] The content not described in detail in this specification belongs to the prior art known to those skilled in the art.
