In the past half a century, with the consumption of resources, the Laochang orefield has entered the rank of resource crisis. In order to alleviate the shortage of mineral resources in the Gejiu tin deposit and prolong the life of the mine, the authors, on the basis of 1∶10 000 tectonic geochemical survey in the study area, analyzed and summarized the geochemical characteristics of 12 elements, used correlation analysis to determine the correlation of elements, used content-area (C-A) fractal method to determine the anomaly threshold, delineated the abnormal range, and then divided the prospecting area.The results show that the 12 elements are highly dispersed, differentiated and enriched in different degrees, among which Pb, Sn, Cu, Bi, As and Cd are the main ore-forming elements in the eastern part of Laochang, Sn and Cu elements have good correlation with Ag, Sb, Zn, Pb, As and Bi elements, and are closely related to mineralization; five prospecting area were delineated, and tin-copper orebodies were found through engineering verification,which shows that the application of tectonic geochemical method in this area can effectively provide scientific basis for the prospecting work.

OBS can enrich the information of the underground structure by obtaining the information of the P-wave and the PS wave,and can obtain the information related to the characteristics of the lithology and the fluid,and reduce the non-uniqueness in the interpretation of the hydrate.In this paper,according to the feature of OBS data,the authors obtained the PP and PS velocity information and common reflection point imaging by repositioning,redirection,wave field separation,mirror image migration,RT rotation,transversal wave migration and other techniques.On such a basis,the authors conducted the P-S wave joint inversion,obtained P-wave impedance as well as S-wave impedance.Through joint interpretation,the authors identified the true distribution area of free gas,and improved the recognition accuracy of fluid characteristics related to hydrates.

The paleo-Shibei area has a good geological background of uranium mineralization, and some mineralization spots and uranium anomalies have been found. The previous work was mainly focused on the surrounding and shallow parts of the mineralization spots, and the evaluation of the overall metallogenic environment and the understanding of the deep metallogenic conditions in the study area were insufficient. The authors briefly introduced the working methods of soil radon, ground gamma energy spectrum and audio frequency magnetotelluric survey, analyzed the uranium metallogenic environment in the study area by comprehensive geophysical survey, delineated the approximate position of uranium ore anomaly on the surface by carrying out soil radon and ground gamma energy spectrum survey, and found the paleo-rock back of ore-controlling fault by carrying out audio frequency magnetotelluric survey (AMT). The characteristics of the development of the fault and ore-controlling strata of Shimaoshan Group were determined, and the inferred interpretation data were verified by drilling, which provides a reference for the exploration of this type of uranium deposits.

In the water shortage area of karst mountain in northwest Hunan, the terrain condition is complex and the electromagnetic interference is strong. In the groundwater exploration, the DC method with strong anti-interference capability is preferred. The engineering practice shows that, when the terrain is relatively gentle and the exploration depth is relatively shallow (about 0~150 m), the small distance combined section method of apparent resistivity + high-density resistivity method is adopted, and when the terrain condition is poor or when the exploration depth is relatively deep (about 0~400 m), the small distance combined section method of apparent resistivity and three-pole IP sounding method are used, and proper inversion and interpretation are carried out, which not only improves the working efficiency but also solves the practical problems, and achieves better water finding effect.

In this study, the high density resistivity imaging method was used to detect the electrical structure in the southern segment of Baobi fault, which lies geographically from Yuhekou to Fangzhuang. As a result, some obvious resistivity discontinuities were revealed below the survey lines. With the aid of surface geological cognition, the authors infer that one of the discontinuities corresponds to Bobi fault. Furthermore, the authors discussed the segmentation of the Bobi fault by combining the previous results of geology and geophysics. The authors consider that Yuhekou is the boundary point.

The separation of anomalies from backgrounds is a critical step in geochemical prospecting. However, the determination of stream sediment geochemical anomalies is always affected by lithologic backgrounds in areas with variable lithologies. If this influence is not eliminated prior to anomaly determination, some serious errors may occur. In fact, a problem of lithologic background is essentially a problem of multiple population, which can be effectively solved by the clustering method based on the Expectation-Maximization (EM) algorithm. In this study, the authors applied the EM clustering method to a geochemical data set from a 1∶200,000 scale stream sediment survey, and then discussed the influence of separating multiple populations on anomaly determination. A practical example demonstrates that geochemical anomalies of stream sediments in lithologically complex regions can be determined in a more reasonable way by using the EM clustering method. This is mainly reflected in two aspects: on the one hand, strong but false anomalies can be eliminated, and on the other hand, weak but important anomalies can be uncovered.

In this study, the surface anomaly distribution characteristics were quickly grasped by performing high-precision magnetic methods on the ground in the Sanhexu mining area of the Xianghualing orefield. Preliminary prediction anomalies are mainly caused by northeastward fault zones. The magnetic anomalies were analyzed by using CSAMT, and a continuous high-resistance uplift was found in the middle and deep parts. The anomaly is inferred to be granite. On such a basis, the authors began inversion of the magnetic anomaly, and it is found that the magnetic object is layered at the edge of the granite and is located in a low-resistance anomaly zone. According to the results of geophysical inference, the favorable metallogenic sites were selected for drilling and exposure. The boreholes ZK502, ZK1601, and ZK3001 successfully verified the inferred granite and revealed high level tin-lead-zinc polymetallic orebody in the sandstone of the Tiaomajian stratum. Based on the results of drilling, geophysical prospecting, and geological background, the authors carried out a comprehensive analysis and study of the metallogenic regularity of the mining area, established a metallogenic model, and delineated the next target for ore prospecting. The above two geophysical methods have good effects on the prediction of deep mineralization.

In the early stage of the exploration project of sandstone type uranium deposit in the south end of Daqing placanticline,many scattered industrial holes were found by using the drilling data of the oil field,which were proved by drilling.In order to further expand the prospecting results,the authors carried out seismic exploration.According to the characteristics of the buried depth of the strata in the working area,the reasonable acquisition parameters were selected,the stratigraphic division of the working area was unified,the sand body was delineated,and then the ancient river course was inferred,the reservoir problem in the exploration of sandstone type uranium deposit was solved,and good results were obtained.It is proved that seismic exploration can be used as the main method in the search for favorable reservoirs in sandstone type uranium exploration.

The impedance of sand reservoir will become lower if the pores are filled with natural gas,so the gas reservoir can be detected by using impedance inversion,which is a common used method.However,the impedance of sand reservoir can be influenced by many kinds of factors such as porosity and mineral composition.As a consequence,the impedance of gas sand may be higher than that of high porosity brine sandstone.In this case,mistake would be caused if post-stack impedance is only used to predict gas sand.Elastic impedance is more reliable than acoustic impedance,because gas sand reservoir can induce AVO anomaly.Simultaneously,in order to improve inversion resolution and accuracy,the authors introduce BP (Basis Pursuit) algorithm to complete elastic inversion.This algorithm is used to decompose seismic signal to even and odd wavelet dictionaries and then reflection coefficient can be obtained by the decomposition coefficients.The method proposed by the authors doesn't need initial low frequency model that traditional inversion method SSI (Sparse Spike Inversion) has to know beforehand. In this case,resolution and accuracy can be improved.The application to synthetic data and field data indicates that this method is more accurate than SSI.

Sedimentary cycle analysis plays an important role in stratigraphic theory research and petroleum exploration and development.Qualitative division of logging curves is a conventional method for dividing sedimentary cycles,which is more accurate at wellbore locations,but the division of sedimentary cycles in non-wellbore locations mainly depends on geological knowledge and has strong subjectivity.Seismic data contain abundant information related to sedimentary cycles.Sedimentary cycles can be divided by using time-frequency attribute curves.In this paper,the generalized S-transform method with better time-frequency resolution is used to calculate the time-frequency attribute curve,and the method is applied to four sedimentary cycle models:normal cycle,inverse cycle,normal-inverse cycle and inverse-normal cycle.The results of cycles division of the model validate the validity of the peak frequency attributes of time-frequency spectrum in the division of sedimentary cycles;However,in the practical application of seismic data,the time resolution of time-frequency spectrum is not high.Teager-Kaiser energy spectrum based on time-frequency spectrum improves the time positioning and focusing of time-frequency analysis results.The division of sedimentary cycles based on Teager-Kaiser energy spectrum attributes can better depict the changes of geological structure and thin interbedded structure.The method is applied to the Jurassic sedimentary cycle division of an oil field in Xinjiang.The results of the division are in good agreement with those of the well data,which verifies the reliability of the method.

With the further advancement of the energy reform,the exploration,development and utilization of geothermal energy in the middle and deep clean energy are imminent.At present,the exploration,development and utilization focus on the middle and deep level, mainly in urban areas,which limits the use of conventional seismic,magnetotelluric and other geophysical prospecting methods, and new methods need to be introduced. In this article,through micro exploration technology in some urban areas to carry out the relevant experiments, comparison of previous high precision gravity,magnetotelluric sounding,geothermal hole data,verified the micro test result,interpretation of stratigraphic classification and tectonic position was consistent with known data,deserves further research and promotion,to realize micro exploration technology in deep geothermal energy in the fast exploration and development is of great significance.

Resistivity tomography is a part of the methods for conducting fault detection in urban areas. In this paper, the application of resistivity tomography to the detection of concealed faults in sedimentary areas was attempted with the fault detection of the Tianjin Canal as an example. The Wenner symmetrical quadrupole device (Wenner α) was employed to data acquisition. In order to obtain higher quality raw data, the authors adopted a number of targeted measures in the field construction. Data processing and inversion adopted a wide range of engineering circles. Using the RES2DINV software, the authors obtained a more reliable resistivity tomography profile. In the geological interpretation of the section, detailed analysis was carried out based on borehole data of the survey area in comparison with the results of shallow artificial earthquakes. The results show that the Jiyunhe fault is a Quaternary fault and shows a definite segmentation. The shallowest upper fault point in the northern section is about 25 m deep, which is a late Pleistocene active fault, and the southern section is about 55 m,which is a middle late Pleistocene fault. This probing work shows that the use of resistivity tomography for the detection of concealed faults in the sedimentary area can achieve good results, but in the process of geological interpretation, the sedimentary evolutionary environment, the geological structure of the basement, and the conductive ion density of the formation should be closely combined with each other. The impact is particularly dependent on other detection results to ensure the harmonization of relevant consequences.

The essential factor for determining the effect of gravity 3D inversion is the observation data, which include the quality, quantity and location. In this paper, the regularized inversion method is used to study the influence of gravity data from different heights and well observations on the inversion results. First of all, gravity data of different heights are inverted separately to verify the relationship between the inversion effect and the height of the observation surface. Then, the gravity data of different heights are inverted together to verify the improvement effect of the joint inversion. On the basis of the beneficial effects of joint inversion, when multi-plane observation data are unavailable, continuation gravity data at different heights are obtained through continuation technology, and joint continuation data and observation data are inverted to improve the inversion effect. This applies to a variety of situations. For example, when only the ground observation gravity data are available, the down continuation data and ground observation gravity data are inverted jointly; when only the airborne observation gravity data are available, the down continuation data and airborne observation gravity data are inverted jointly. Finally, taking advantage of the fact that the measured data in the boreholes are closer to the anomaly, it is added to the inversion to further improve the vertical resolution.

Compared with conventional surface seismic data,VSP seismic data have many advantages,such as abundant wavefield information,high resolution and signal-to-noise ratio information.Reverse time migration (RTM) method based on two-way wave equation is considered to be the most accurate imaging method for seismic data at present.The combination of the VSP data and RTM method is helpful to describing the structures beside wells and identifying the complex geological structures accurately.Based on the two-dimensional (2D) variable density acoustic wave equation,the authors studied the high-precision RTM method of VSP data using the optimal staggered-grid finite-difference method.For different aspects of this VSP RTM method,different measures were adopted.First,the authors used the optimal staggered-grid finite-difference method to realize high-precision wavefield extrapolation.Second,the authors used the PML absorbing boundary condition to suppress boundary reflections caused by the limited computing space of model.Third,the authors used the effective boundary storage strategy to reduce the storage requirements of source wavefields.Fourth,the authors used the normalized cross-correlation imaging condition of sources to handle RTM imaging of VSP data.Finally,the high-order Laplacian filtering method was used to suppress the low-frequency noises of RTM imaging results.The different model test results show that the VSP RTM method proposed in this paper can achieve high-precision RTM imaging for VSP data.Compared with the conventional RTM method of surface seismic data,the RTM method of VSP data can more accurately identify the underground complex geological structures, such as the high-steep structures and the structures with sharp velocity changes,which verifies the effectiveness of the proposed method.

Conventional coal seam gas content prediction methods are mostly based on logging constrained seismic attribute inversion and linear mapping model,which makes the prediction accuracy difficult to control,and severely limits the universality of the method.This paper starts with two aspects:seismic attribute optimization and BP neural network prediction model improvement.Using the Q-type clustering analysis method,the seismic attributes of the extracted target reservoirs are classified and optimized,and four kinds of seismic attributes with good correlation with the geological targets are obtained.The particle swarm optimization algorithm is further used to BP neural network algorithm.The connection weights of the input layer and the hidden layer and the threshold of the hidden layer are optimized,and the PSO-BP prediction model is constructed.The PSO-BP model is trained by using the preferred seismic attributes and gas content data of the well location.Based on the trained PSO-BP model,the coal seam gas content prediction in the study area is carried out with the preferred seismic attributes of the entire work area as input.The comparison between the predicted gas content of the well position and the measured results shows that the prediction method has high accuracy.Therefore,it can be considered that the PSO-BP prediction model and the corresponding prediction method flow can be effectively applied to the prediction of coal gas content in coal reservoirs.

The finite element method has the characteristics of strong adaptability in simulating the electromagnetic response of rugged topography and complex geological bodies. In recent years, it has been widely used in the three-dimensional (3D) forward modeling of magnetotelluric (MT) sounding. However, the finite element method also has some shortcomings in terms of computational efficiency. The large amount of calculation and long running time of the method are the main factors that lead to the lag of the practical process of the 3D MT inversion technology based on the finite element method compared with the 3D MT inversion technology based on the finite difference method. In order to improve the 3D forward speed of MT, the authors adopt the forward modeling scheme which uses the direct solver PARDISO and does not need divergence correction to solve the large-scale linear equations corresponding to the vector finite element method, and obtain the MT response of the geoelectric model under such different terrain conditions as flat and rugged topography. Under the conditions of medium-scale calculation, through the comparison between the direct solution method without divergence correction and the iterative solution method with divergence correction, the authors have detected that the direct solution method without divergence correction has advantages in calculation accuracy and calculation time, especially in the calculation. In terms of time, the ratio of the calculation speed of the direct solution and the iterative solution is raised by more than ten times.

The 1∶50 000 gravity far area terrain correction is generally obtained from the 1∶50 000 DEM elevation model correction in the survey area. 1∶50 000 DEM can be spliced according to different grid spacings, which correspond to different terrain correction accuracies; RGIS is calculated by its own elevation database, and the topographic correction of 1∶50 000 gravity far area in the survey area is completed. The authors chose the 1∶50 000 gravity remote area I (2~20 km) land reform of Zangjiazhuang area in Qixia City, Shandong Province, as an example. Through the use of 25, 50, 100, 200 m four grid node spacings for 1∶50 000 DEM data splicing and the use of the improved bilinear interpolation method, the authors calculated the terrain correction and mean square error in the far area I of gravity. Compared with the terrain correction mean square error of gravity far area I of RGIS own elevation reservoir, it is confirmed that the terrain correction accuracy of gravity far-Ⅰ area based on 1∶50 000 DEM elevation model is better than that of gravity far-Ⅰ area with RGIS.

Airborne gravimetry surveying is a geophysical survey method with the aircraft as a carrier. It can rapidly and efficiently extract middle and high frequency earth’s gravity field information in large areas. The commercialization of aeronautical gravity measurement technology is due to the maturity of dynamic differential GNSS positioning technology, which greatly improves the accuracy of dynamic velocity measurement and acceleration calculation of the carrier. And the accuracy of carrier dynamic positioning using the differential GNSS positioning technology depends on the accuracy of the ground reference station coordinates. In the actual work, through the establishment of GNSS control network to calculate the ground GNSS base station coordinates on the synchronization observation of national GPS geodetic control network, it not only spends much time and needs much cost but also has many difficulties in establishing the ground GNSS base station in the rare swamp, plateau, desert, unmanned areas and distant mainland’s island reef areas. With the construction of CORS station in China, the precision and the net dimension have been continuously improved. By using the data of CORS station, the method for determining the coordinates of the ground GNSS base station is employed by GAMIT, which has become a new trend. With the actual data of a survey area as an example, the authors conducted check and analysis of the base station coordinate accuracy and the measured gravity anomaly of the two methods, and readers can understand the application effect of the CORS system in the ground GNSS base station calculation in airborne gravimetry. It shows that the CORS system can not only meet the accuracy requirements of airborne gravimetry, but also improve the work efficiency.

In this paper, inverse time migration imaging of center loop transient electromagnetic sounding is studied. In view of the fact that the propagation velocity of electromagnetic wave in the earth is much lower than that of the speed of light in the vacuum, an inverse time migration imaging algorithm is designed which is suitable for transient electromagnetic sounding in the center loop observation configuration. The core idea of the algorithm is to obtain the total wave field value of the imaging point according to the superposition of the wave field value of different observation points at the same time of the imaging point. Based on this algorithm, inverse time migration imaging was performed on a measured center loop transient electromagnetic sounding data. It is shown that the results of inverse time migration imaging are in good agreement with the actual situation and can obtain better processing effect. Therefore, inverse time migration imaging is an effective data processing method for transient electromagnetic sounding.

In the geochemical stream sediment survey, obvious differences in geochemical backgrounds of different geological bodies will affect the anomaly delineation and even lead to enhancement of anomalies irrelevant to mineralization, which weakens the mineralization-related weak anomalies. In this paper,the influence of step effect data on the fractal distribution form is discussed from the mathematical view based on the superposition law of fractal distribution, and an improved method for eliminating step effects in concentration-area fractal theory is proposed.In this method, the authors divide the study area based on geochemical background and then discuss fractal distribution forms respectively.The result shows that this method can accurately filter irrelevant lithology information and identify weak anomalies caused by mineralization in low-background sub-zone. It is applicable to the extraction of geochemical mineralization-related anomaly in the areas seriously affected by lithology.

Among a variety of complicated factors that are related to sand liquefaction,8 discriminant factors have been picked out of 72 samples in the earthquake event happened in Tangshan without losing any tiny but useful information.By calculating Gini coefficient with CART algorithm,a decision tree has been undertaken to divide the features of original sample dataset.Moreover,in order to reduce overfitting risk of a single decision tree,random forest with multiple trees have been created.Meanwhile,with 10-fold cross validation,best estimators with 5 max-depth and 20 trees can perform with much more stable and reliable results.The research shows that,compared to standard penetration test from Code for seismic design of buildings,both decision tree and random forest have a better predicting precision, especially there have been no false classifications with higher stability using random forest model.

Soil organic carbon (SOC), as an important element to be analyzed in multi-purpose regional geochemical survey, affects the migration and transformation of other elements in the soil. Therefore, it is a significant index in evaluating the soil quality. The traditional methods of measuring SOC include potassium dichromate oxidation method and combustion method.The former is complicated to operate in practical application and there is also some pollution to the environment. Through the pretreatment of soil with H₃PO₄ to remove the interference of inorganic carbon, and the detailed discussion of the best conditions in the working process of the analytical instrument, which include the temperature of the oxidation furnace, oxygen adding quantity, oxygen pressure and the carrier gas pressure and some other factors, an analytical method for the direct solid injection and determination of total organic carbon in soil by oxidative combustion and gas chromatographywas established and optimized in this paper. The experimental results show that the correlation coefficient R² of this method is 0.9999, and the detection limit is 0.012%. According to the verification of the Certified Reference Materials for the Chemical Composition of Soils, the measured value is consistent with the certified value with the precision of 1.10%~4.11% (n=12). This method has the advantages of high efficiency and simple operation, and is suitable for the determination of organic carbon in different types and values of soil samples.

In order to measure the diffusion coefficient of hydrocarbon gases in rocks more accurately and provide parameters for the evaluation of the loss and preservation of natural gas accumulations, the authors developed an experiment apparatus to simulate the diffusivity of natural gas in depth.The hardware structure, technical parameters of the apparatus and the experimental flow for simulating the deep natural gas diffusion coefficient were described. Taking the shale of Cambrian Niutitang formation and the dense limestone of Permian Maokou formation as examples, the authors simulated the natural gas diffusion in rocks under high temperature and high pressure, and calculated their diffusion coefficients. The results show that the test data of the deep natural gas diffusion coefficient are reliable by using the apparatus, which provides a technical means for the evaluation of deep gas preservation conditions.

In order to understand the status of soil heavy metal pollution in Anqiu Area, Shandong Province,10 194 soil samples are systematically collected,the contents of 8 heavy metal elements including Cd, Hg, Pb and As are tested and analyzed.The geochemical distribution characteristics of heavy metal elements and their possible sources are discussed by using geostatistical and multivariate statistical methods.The results show that the average contents of Cd, Hg and As in the soil of the study area are similar to the background values of Weifang soil, and the average contents of other elements are slightly higher than the soil background values of Weifang.The average contents of the 8 heavy metal elements are all lower than risk screening values of standard. According to cluster analysis,eight heavy metal elements are mainly divided into four categories.The first category is Cr, Ni, Cu and Zn, whose distributions are mainly affected by natural factors such as the parent material of the soil, while Zn is also affected by human activities.The second category is Cd,Pb and the third category is Hg. The distribution characteristics of these elements are greatly affected by human activities such as metal smelting and processing, transportation, mining, etc.The fourth category is As, which is not only inherited from the the parent material of the soil, but also affected by human activities. The soil environmental quality in the study area is evaluated by Soil Environmental Quality Risk Control Standard for Soil Contamination of Agricultural Land(GB 15618—2018),the results show that the soil environment in the study area is mainly safe zone, risk-freeand. Point source pollution only exists in some places.

The method proposed in this paper is based on the use of land quality geochemical survey data and the collected comprehensive information on agricultural land environment to accurately classify the land grades in Linxia, Gansu. Taking the agricultural landform and yield per mu as macro-level indicators, the authors used the soil traits, soil nutrients, land cleanliness and life-health elements as micro-indicators to decompose, quantify and assign various indicators. The authors objectively and comprehensively used the new viewpoints of macro-index grading and micro-level grading, established cadastral archives of agricultural land quality survey, and provided an important basisfor land management decision-making.

Qingshan Provincial Geopark in Jiaxiang County, with a total area of 2.43 km², is rich in geological relics. It is a small geopark mainly composed of typical Sanshanzi Formation stratigraphic profile, rich structural traces, spring landscape and cave type geological relics. In order to further promote the development of tourism and expand the landscape area of karst caves, the authors used comprehensive geophysical methods to look for hidden karst caves, and utilized microgravity survey methods to delineate three anomalies, all of which are of continuous low gravity characteristics. At the same time, the high-density resistivity method was used to verify the delineated anomalies. Finally, three karst caves with a certain scale were found, and good exploration results were achieved.

Collapse occurs during the excavation of a highway tunnel, and hence it is urgent to use geophysical method to detect other potential collapse areas. In view of the large difference of the terrain, the lush surface vegetation and the low resistivity of the surrounding rock, the authors selected the opposing coils transient electromagnetic method (OCTEM) as the equipment of this method which is relatively light and it has high resolution in reflecting the resistivity. Firstly, OCTEM response of underground collapses buried in conductive host was calculated, and the results theoretically proved that OCTEM was sensitive to underground resistivity and had high resolution, and then the OCTEM detection result was compared with the high-density electrometer detection result. It is proved that they correspond well, and both reflect the known collapse area. It is shown that OCTEM can be applied to rapid detection of collapse area in the highway tunnel under construction.

Geological and underground pipeline detection was carried out in several urban metro exit areas in the loess area by using ground penetrating radar (GPR). The distribution of soil layer in the loess area was emphatically studied. The GPR images of PVC pipelines and metal pipelines in the loess area under the conditions of holes, seepage and soil collapse were analyzed, and the respective GPR scans of underground pipelines in the loess area were summarized. By describing the characteristics of the images, the authors summarized the general analysis methods and rules of applying GPR to detecting urban geological stratification and pipeline radar images in the loess area, and used the image laws of "black-white-black" and "white-black-white" to analyze the GPR images, which provides a good guidance for subsequent engineering construction.

In order to realize the rapid detection and identification of underground power cables, this paper proposed a method based on ground penetrating radar for imaging and identification of underground cables. Firstly, the characteristics of the detection waveforms of the underground charging cable and the non-charged medium under the action of ground penetrating radar were analyzed by forward modeling experiments, which highlighted the particularity of the reflected waveform of the charged cable, and then the magnetic field radiation of the cable under the common wiring mode was established based on the principle of magnetic field superposition. The calculation model explained the cause and particularity of cable detection waveform from the perspective of cable structure and magnetic field distribution, and further highlighted the difference between the cable and other non-charged formation media. A method for detecting and identifying underground cable based on ground penetrating radar was proposed. Finally, the proposed method was verified by inversion experiments. The experimental results show that the proposed method has a good application effect in cable detection and identification.

Due to the external dynamic geological process, the protection of Dazu Rock Carvings sites needs high precision geological engineering survey data, and the digital borehole panoramic camera technique can accurately obtain the structure characteristics and underground rock mass discontinuities with precision of 1 mm. In this study, the authors used digital panoramic borehole camera technique to analyze the geotechnical engineering of Thousand-Hand Kwan-yin at Dazu, Chongqing, and the results show that the integrity of the rock mass in this region is good, with the discontinuities being mainly manifested as joints and constituting the main seepage channel in the region. This technique can provide original imaging data for the geotechnical engineering of Thousand-Hand Kwan-yin. It offers a advantage for the protection of cultural relics sites, which improves the implementation and decision-making of engineering.