Urban shallow surface geology detection method

Abstract

The invention provides an urban shallow surface geology detection method, which adopts a transient electromagnetic method and a seismic wave method for detection, determines hole information according to a detection result, then carries out result proximity imaging based on fusion of cross-hole electromagnetic wave CT and cross-hole elastic wave CT, and further carries out accurate physical exploration on an unfavorable geologic body. The exploration result of earth surface and in-hole geophysical prospecting can provide targeted positioning information for geological drilling, real form imaging of drilling well logging and in-hole laser scanning fusion is carried out, and the efficiency and precision of geological drilling are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of geological detection, and in particular relates to a method for urban shallow surface geological detection. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] The construction of underground projects such as subways and tunnels will inevitably encounter common unfavorable geology such as faults, broken rock masses, water-rich conditions, karst caves and weak rock masses. Therefore, it is very important to carry out advanced detection of unfavorable geological bodies during the construction stage to ensure construction safety and progress.

[0004] After decades of development, the technology of advanced detection of adverse geological structures has made great and comprehensive progress, including destructive detection methods, such as advanced pilot holes and advanced drilling methods, as well as non-destructive detection methods, such as seismic emission, electromagnetic, and direct current methods. It is worth noting that the transition from a single detection method to a systematic and comprehensive detection of multiple methods is crucial to reducing the multi-solution nature of detection results and improving detection accuracy, and is one of the important development trends of geological detection methods. In addition, when conducting geological detection in the shallow surface of the city, not only is the detection space limited, but many interferences such as urban noise cannot be ignored, which further increases the difficulty and challenge of geological detection.

[0005] Therefore, how to conduct comprehensive and accurate geological exploration of the shallow surface of the city is a problem that needs to be solved at present. Summary of the invention

[0006] In order to overcome the shortcomings of the above-mentioned prior art, the present invention provides a method for urban shallow surface geological exploration, which realizes more comprehensive and accurate geological exploration of the urban shallow surface through "ground geophysical exploration + borehole geophysical exploration + geological drilling" and combined with the "a priori + a posteriori dual drive" detection method.

[0007] To achieve the above object, the first aspect of the present invention provides a method for urban shallow surface geological exploration, comprising:

[0008] The area to be surveyed is subjected to ground physical detection using an electromagnetic method and a seismic emission method combined with an electric-seismic collaborative detection mode to obtain shallow surface geological anomaly areas;

[0009] Taking the shallow surface geological anomaly area as prior information, the cross-hole electromagnetic wave CT and cross-hole elastic wave CT fusion method are used to conduct physical detection in the hole to obtain the morphological characteristics of the underground structure.

[0010] The morphological characteristics of the underground structure obtained by physical detection in the hole are used as prior information, and the borehole logging technology and laser scanning are used for geological drilling to identify the abnormal bodies in the ground and evaluate the size, shape and location of the abnormal bodies;

[0011] The identification results obtained from geological drilling are used as a posteriori information for physical detection in the hole to reversely guide the process of physical detection in the hole;

[0012] The results of physical exploration in the hole are used as a posteriori information of ground physical exploration to reversely guide the process of ground geophysical exploration;

[0013] Repeat the above steps until all areas to be detected are detected.

[0014] One or more of the above technical solutions have the following beneficial effects:

[0015] In the present invention, a joint electric-seismic collaborative detection mode is adopted for detection, and the detection results are used as prior information for physical detection in the hole. Subsequently, physical detection in the hole based on the fusion of cross-hole electromagnetic wave CT and cross-hole elastic wave CT is carried out to further implement precise physical exploration of unfavorable geological bodies; the results of physical detection in the hole are used as prior information for geological drilling, and borehole logging technology and laser scanning are used for geological drilling, which can identify abnormal bodies existing underground in more detail, and the identification results obtained by geological drilling are used as a posteriori information for physical detection in the hole, which reversely guides the process of physical detection in the hole and improves the detection accuracy; the results of physical detection in the hole are used as a posteriori information for ground physical detection, which reversely guides the process of ground geophysical exploration and improves the accuracy of exploration; through "ground geophysical exploration + borehole geophysical exploration + geological drilling", and combined with the "prior + posteriori dual-drive" detection method, a more comprehensive and accurate geological detection of the shallow surface of the city is achieved.

[0016] Advantages of additional aspects of the present invention will be given in part in the following description, and in part will become obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0018] Figure 1 This is a flow chart of the urban shallow surface geological detection method in Example 1 of the present invention. DETAILED DESCRIPTION

[0019] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0020] It should be noted that the terms used herein are for describing specific embodiments only and are not intended to be limiting of exemplary embodiments according to the present invention.

[0021] In the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0022] Embodiment 1

[0023] This embodiment discloses a method for urban shallow surface geological detection, including:

[0024] The area to be surveyed is subjected to ground physical detection using an electromagnetic method and a seismic emission method combined with an electric-seismic collaborative detection mode to obtain shallow surface geological anomaly areas;

[0025] Taking the shallow surface geological anomaly area as prior information, the cross-hole electromagnetic wave CT and cross-hole elastic wave CT fusion method are used to conduct physical detection in the hole to further reveal the morphological characteristics of the underground structure.

[0026] Taking the morphological characteristics of underground structures obtained by physical detection in the hole as prior information, borehole logging technology and laser scanning are used for geological drilling to more thoroughly identify underground anomalies such as faults, caves, fracture zones, etc., and their size, shape and location are evaluated by observing and describing the cores extracted from the drilling and recording the borehole catalog in detail;

[0027] The results of geological drilling are used as a posteriori information for borehole physical detection, which can reversely guide the on-site implementation, data processing and interpretation of borehole geophysical exploration, thereby improving the detection accuracy.

[0028] The results of physical detection in the hole are used as a posteriori information for ground geophysical exploration, which can provide reverse guidance for the on-site implementation, data processing and interpretation of ground geophysical exploration, thus improving the accuracy of exploration.

[0029] Repeat the above steps until all areas to be detected are detected.

[0030] Combination Figure 1 A method for urban shallow surface geological detection proposed in this embodiment is described in detail:

[0031] Step 1: Exploration preparation phase, it is necessary to have a detailed understanding of the surface topographic characteristics and underground hydrogeological conditions of the exploration area;

[0032] Step 2: Conduct some field experiments in the area to be explored in advance to obtain relevant parameters of the selected method that are applicable to the area to be explored, such as spectrum characteristics and frequency range, so as to more accurately identify and predict adverse underground geology;

[0033] Step 3: Select appropriate measuring points according to the spatial distribution characteristics of buildings (structures) in the exploration area, and determine the ground geophysical observation system, including the seismic wave reflection observation system, micro-seismic exploration observation system, high-density resistivity observation system and transient electromagnetic observation system. The measuring points should be distributed as evenly as possible to ensure that comprehensive and accurate data can be obtained, and appropriately increase measuring points on both sides or around the buildings (structures) to eliminate the influence of buildings (structures) through data processing and analysis;

[0034] Among them, micro-motion exploration can collect urban traffic noise data, determine the spectral characteristics and dominant frequency range of noise signals in complex traffic scenarios, and thus realize non-destructive and convenient detection of disaster sources in urban traffic scenarios with "noise as the source".

[0035] Step 4: The above four methods are used to carry out geological exploration respectively, and necessary data processing steps such as preprocessing, denoising, and correction are performed on the collected data, and the data are imaged;

[0036] Step 5: Interpret the imaging results of ground exploration to obtain geological information of the detection area and determine the shallow surface geological anomaly area. The above steps are used to realize ground electric-seismic coordinated detection;

[0037] Step 6: Design a borehole geophysical exploration scheme for the geological anomaly area obtained by the coordinated electric-seismic detection, based on its spatial distribution position and scale. The selection of the measuring point spacing should take into account the detection accuracy and efficiency. A smaller measuring point spacing should be used at the boundary of the anomaly area; in the relatively uniform area inside the anomaly body, the measuring point spacing can be appropriately increased to improve work efficiency while ensuring the detection effect;

[0038] Step 7: After drilling according to the measuring points, the physical detection in the hole is carried out by using the method of fusing cross-hole electromagnetic wave CT and cross-hole elastic wave CT. The parameters of the two methods are coordinated with each other in the selection of data acquisition parameters, which mainly involves the selection of wave frequencies, so as to make the propagation characteristics of the two waves have good complementarity in the detection area as much as possible, so as to better reflect the different characteristics of the geological body;

[0039] Step 8: Use the weighted average method and assign corresponding weights according to the importance and reliability of different geological features, organically combine the information of electromagnetic waves and elastic waves, perform geological interpretation on the close-range imaging of cross-hole electromagnetic wave CT and cross-hole elastic wave CT fusion, judge the morphological characteristics of the unfavorable geological structure in the survey area according to the range of the relatively low-speed area in the wave velocity map, and compare the scale, location and other information of the unfavorable geological body with the ground geophysical exploration results, and use the a posteriori information to correct the selection of data processing parameters and the determination of interpretation criteria in ground geophysical exploration;

[0040] Step 9: First, set the drilling borehole measurement points according to the spatial position of the geological anomaly body determined by surface geophysical prospecting and in-hole geophysical prospecting. The measurement point range should fully cover the geological anomaly body, and use dense drilling for relatively developed geological anomaly bodies. Secondly, according to the depth range of the geological anomaly body determined by surface geophysical prospecting and in-hole geophysical prospecting, determine the minimum depth of the borehole in the drilling. The borehole should at least penetrate the bottom of the anomaly body. If the depth of the anomaly body is large or the geological conditions below it are unclear, the borehole should be appropriately deepened;

[0041] Step 10: During the geological drilling process, rock and soil samples are taken along the depth of the hole. The samples are used to determine the physical and mechanical properties of the rock and soil. Secondly, through laser scanning in the hole, laser pulses are emitted and the round-trip time of the pulses is measured to determine the distance between the sensor and the target. The location and size information of the unfavorable geological body can be obtained, and its morphological characteristics can be obtained through multiple scanning and measurements;

[0042] Step 11: After the detection is completed, summarize the geological drilling results to determine whether the observation system needs to be adjusted in the next stage of borehole geophysical exploration and ground geophysical exploration, whether the data processing parameters or imaging methods need to be adjusted, and what matters need to be paid attention to during the interpretation process.

[0043] Step 12: If necessary, further compare the results of in-hole geophysical exploration with those of ground geophysical exploration, and analyze whether there are any parts in the ground geophysical exploration that need to be improved, so as to guide the next stage of ground geophysical exploration, data processing, imaging and interpretation.

[0044] Step 13: By adjusting and correcting the ground and in-hole geophysical exploration, repeat steps 1 to 9 to carry out the next stage of dual-drive geological exploration.

[0045] In this embodiment scheme, the prior process is first implemented in the detection stage, that is, the electro-seismic collaborative detection of electromagnetic methods and seismic wave methods is realized on the ground. The detection results are used to guide in-hole geophysical exploration and provide constraint information such as hole location and depth to improve the accuracy of close imaging and inversion accuracy using the fusion of cross-hole electromagnetic wave CT and cross-hole elastic wave CT in the hole. The results of surface and in-hole geophysical exploration will further constrain geological drilling, make the operation more targeted, provide targeted positioning information for drilling, and improve the accuracy of real-form imaging fused with borehole logging and in-hole laser scanning.

[0046] Secondly, after the detection is completed, the a posteriori process is realized through analysis and summary. That is, the results of geological drilling will reversely guide the implementation of in-hole geophysical exploration, further correct the implementation, data processing and results interpretation processes, and will also guide ground geophysical exploration to a certain extent, so as to continuously improve the accuracy of ground geophysical exploration. The results of in-hole geophysical exploration will also play an important role in guiding and correcting the ground detection process.

[0047] Through improved ground-hole-drilling combined detection, guided and corrected by a priori and a posteriori dual driving programs, the entire geological exploration process can form a closed-loop operation, with each part complementing each other, promoting the overall detection method to move towards high precision and high inversion accuracy.

[0048] In this embodiment, the ground geophysical exploration module adopts electric-seismic collaborative exploration combined with seismic wave reflection method, micro-seismic exploration, high-density resistivity method and transient electromagnetic method. The detection results will provide prior information for subsequent in-hole geophysical exploration, so as to improve the inversion accuracy of the in-hole geophysical exploration method; then, close imaging based on the results of cross-hole electromagnetic wave CT and cross-hole elastic wave CT fusion is carried out to further implement precise physical exploration of unfavorable geological bodies; the exploration results of surface and in-hole geophysical exploration will provide targeted positioning information for geological drilling, implement real morphological imaging of borehole logging and in-hole laser scanning fusion, improve the efficiency and accuracy of geological drilling, and realize a series of prior processes; through the imaging results of geological drilling and in-hole laser scanning, the imaging accuracy of surface and in-hole geophysical exploration is reversely corrected, guiding the implementation and imaging of ground and in-hole geophysical exploration, and improving the accuracy of geophysical exploration inversion.

[0049] Those skilled in the art should understand that the modules or steps of the present invention described above can be implemented by a general-purpose computer device, or alternatively, they can be implemented by a program code executable by a computing device, so that they can be stored in a storage device and executed by the computing device, or they can be made into individual integrated circuit modules, or multiple modules or steps therein can be made into a single integrated circuit module for implementation. The present invention is not limited to any specific combination of hardware and software.

[0050] Although the above describes the specific implementation mode of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without creative work are still within the scope of protection of the present invention.

Claims

1. A method for urban shallow surface geological exploration, characterized in that: include: The area to be surveyed is subjected to ground physical detection using an electromagnetic method and a seismic emission method combined with an electric-seismic collaborative detection mode to obtain shallow surface geological anomaly areas; Taking the shallow surface geological anomaly area as prior information, the cross-hole electromagnetic wave CT and cross-hole elastic wave CT fusion method are used to carry out physical detection in the hole to obtain the morphological characteristics of the underground structure. The morphological characteristics of the underground structure obtained by physical detection in the hole are used as prior information, and the borehole logging technology and laser scanning are used for geological drilling to identify the abnormal bodies in the ground and evaluate the size, shape and location of the abnormal bodies; The identification results obtained from geological drilling are used as a posteriori information for physical detection in the hole to reversely guide the process of physical detection in the hole; The results of physical detection in the hole are used as a posteriori information of ground physical detection to reversely guide the process of ground geophysical exploration; Repeat the above steps until all areas to be detected are detected.

2. A method for urban shallow surface geological exploration as claimed in claim 1, characterized in that: According to the surface environmental characteristics of the area to be surveyed, seismic wave reflection method, micro-seismic exploration, high-density resistivity and transient electromagnetic method are used for detection respectively.

3. The urban shallow surface geological detection method according to claim 1, characterized in that: According to the geological anomaly area obtained by electro-seismic coordinated detection, the detection plan for in-hole physical detection is designed based on the spatial distribution position and scale of the geological anomaly area; among which, the spacing between measuring points set at the boundary of the anomaly area is smaller than the spacing between measuring points set in the uniform area of ​​the anomaly area.

4. A method for urban shallow surface geological exploration as claimed in claim 3, characterized in that: The method of fusing cross-hole electromagnetic wave CT and cross-hole elastic wave CT is used for physical detection in the hole. The close-range imaging of the fusion of cross-hole electromagnetic wave CT and cross-hole elastic wave CT is geologically interpreted. According to the range of the relatively low-speed area in the wave velocity map, the morphological characteristics of the adverse geological structure in the survey area are judged.

5. The urban shallow surface geological detection method according to claim 4, characterized in that: The morphological characteristics of the poor geological structure in the survey area are compared with the results of ground physical detection to determine the scale and location of the poor geological body, which is used as a posteriori information to correct the selection of data processing parameters and the determination of interpretation criteria in ground physical detection.

6. A method for urban shallow surface geological exploration as claimed in claim 4, characterized in that: The weighted average method is used to assign corresponding weights according to the importance of different geological features, and the results of cross-hole electromagnetic wave CT and cross-hole elastic wave CT detection are fused.

7. The urban shallow surface geological detection method according to claim 1, characterized in that: During the drilling process of geological drilling, rock and soil samples are taken along the depth of the hole to measure the physical and mechanical properties of the rocks and soil. By laser scanning in the hole, the distance from the laser emission source to the unfavorable geological body is determined to obtain the morphological characteristics of the unfavorable geological body.

8. The urban shallow surface geological detection method according to claim 1, characterized in that: According to the geological anomaly area obtained by the electric-seismic collaborative detection mode, the spatial position and scale of the geological anomaly area are determined, and the drilling position and depth information of the physical detection in the hole are determined according to the determined spatial position and scale of the geological anomaly area.

9. The urban shallow surface geological detection method according to claim 1, characterized in that: Drilling borehole measuring points shall be set according to the spatial position of the geological anomaly body determined by ground physical detection and physical detection in the hole, and the measuring point range shall fully cover the geological anomaly body; the minimum depth of the borehole during drilling shall be determined according to the depth range of the geological anomaly body determined by ground physical detection and physical detection in the hole, and the borehole shall at least penetrate the bottom of the anomaly body.

10. The urban shallow surface geological exploration method according to claim 2, characterized in that: The data collected by ground physical detection are denoised and corrected, and the data are imaged and interpreted to obtain geological information of the detection area and determine shallow surface geological anomaly areas.

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