Hole-tunnel induced polarization water exploration structure construction method and inversion water exploration method

Abstract

A hole-tunnel induced polarization water exploration structure construction method, comprising steps: arranging a plurality of forward boreholes (2) at intervals on an outer edge area of a tunnel face; respectively providing in each forward borehole (2) an in-hole exploration cable having a power supply electrode A (5) and a power supply electrode B (6); providing in an array a plurality of out-hole exploration electrodes, which are configured as a measurement electrode M (7) and a measurement electrode N (8), outside the area occupied by the forward boreholes (2) of the tunnel face, wherein the power supply electrodes form a power supply closed loop, and the measurement electrodes form a measurement closed loop. Also provided is an inversion method for a hole-tunnel induced polarization water exploration structure, comprising steps: acquiring hole-based initial observation data, and forming exploration observation data; establishing a corresponding initial resistivity model and a corresponding initial polarizability model, and carrying out a conventional inversion electrical method to obtain a resistivity inversion model; establishing a tunnel resistivity and polarizability clustering joint inversion objective function; and performing iterative inversion to obtain a final inversion result.

Description

Construction method of hole-tunnel induced polarization water exploration structure and inversion water exploration method

[0001] The present invention claims priority to the Chinese patent application filed with the Patent Office of China on August 21, 2023, with application number 202311054593.5 and invention name “Construction method and inversion water exploration method of hole-tunnel induced polarization water exploration structure”, the entire contents of which are incorporated by reference into the present invention. Technical Field

[0002] The present invention belongs to the technical field of geophysical exploration, and in particular relates to a construction method of a hole-tunnel induced polarization water exploration structure and an inversion water exploration method. Background Art

[0003] Currently, a large number of deep tunnels in difficult mountainous areas and cross-river and sea tunnels are emerging in my country's tunnel construction, characterized by long tunnel lines and great buried depths. Various types of poor water-bearing geological deposits are more hidden and more catastrophic, requiring higher resolution and more difficult targets to detect. They are highly susceptible to sudden water inrush disasters during tunnel construction, which places higher demands and challenges on the accuracy of tunnel advance detection. The induced polarization method is an electrical detection method that uses the induced polarization effect of water-bearing geological bodies for detection and is sensitive to water bodies. Currently, tunnel advance water detection methods based on induced polarization, such as Beam and TIP, have been applied in China and abroad for the advance prediction of water-bearing tunnel structures. The TIP method can achieve the quantitative prediction of the location of large water-bearing structures.

[0004] However, the above methods use the tunnel side wall and the tunnel face for detection.

[0005] (1) Limited by the confined environment of the tunnel, its detection resolution is usually at the meter level, making it difficult to achieve precise detection of small water-bearing structures. Secondly, the induced polarization field generated by the above method is distributed near the tunnel, resulting in poor response to water-bearing structures farther away. As a result, the detection distance of the above method is relatively short, which cannot meet the needs of exploring water-bearing structures farther away.

[0006] (2) At the same time, in the processing and imaging of induced polarization data, the traditional polarizability inversion is based on the resistivity inversion results. The imaging introduces many multi-solution factors of resistivity inversion, making it difficult for the polarizability inversion to converge. The polarizability itself has a natural boundary condition in the interval (0,1). The traditional inversion method often ignores this condition, resulting in the polarizability value exceeding the limit and the inability to obtain reliable inversion results. At the same time, induced polarization belongs to potential field detection. It is affected by the volume effect and is difficult to perceive the boundary information of the anomaly body, which in turn makes it impossible to perform fine inversion imaging of the anomaly boundary, resulting in the inability to perform accurate geological interpretation.

[0007] In addition, induced polarization detection requires high data accuracy, so it is necessary to focus on the initial observation data errors caused by electrode polarization and multi-core cable coupling. The former is caused by the continuous power supply and measurement of metal electrodes, and the latter is caused by the simultaneous power supply and measurement of multiple electrodes in a single multi-core cable.

[0008] Summary of the Invention

[0009] Therefore, the technical problem to be solved by the present invention is to provide a construction method and an inversion water exploration method for a hole-tunnel induced polarization water exploration structure, which improves the detection distance of the induced polarization field to the detection target. Through excitation in the hole and reception at the face, three-dimensional effective information of the water-conducting structure in front can be obtained, avoiding the two problems of continuous power supply and measurement of a single metal electrode and the simultaneous power supply and measurement of multiple electrodes in the same cable. It fundamentally and naturally eliminates the system interference of electrode polarization and multi-core cable coupling, and is suitable for induced polarization fine detection.

[0010] The present invention provides a construction method of a hole-tunnel induced polarization water exploration structure, comprising the following steps:

[0011] Multiple forward boreholes are arranged at intervals in the outer edge area of ​​the tunnel face;

[0012] An in-hole detection cable is respectively arranged in each of the forward boreholes, each of the in-hole detection cables has a plurality of detection electrodes, and each detection electrode in each of the in-hole detection cables is respectively configured as a power supply electrode A and a power supply electrode B;

[0013] A plurality of out-of-hole detection electrodes are arranged in an array in an area outside the area occupied by each of the forward drilled holes on the tunnel face, wherein each of the out-of-hole detection electrodes is configured as a measuring electrode M and a measuring electrode N;

[0014] The power supply electrodes A and B form a power supply closed loop, and the measurement electrodes M and N form a measurement closed loop.

[0015] The present invention also provides an inversion water exploration method for a hole-tunnel induced polarization water exploration structure formed based on the construction method of the hole-tunnel induced polarization water exploration structure, comprising:

[0016] The initial observation data acquisition step is used to obtain the induced polarization data of the hole-tunnel induced polarization water exploration structure, using the following method:

[0017] defining any one of the plurality of forward boreholes as a first borehole, selecting one of the detection electrodes in the borehole detection cable in the first borehole as a power supply electrode A and the other as a power supply electrode B, and supplying power so that the power supply electrode A and the power supply electrode B form a power supply closed loop, wherein the power supply electrode A is located between the tunnel face and the power supply electrode B;

[0018] Select one of the plurality of out-of-hole detection electrodes as the measuring electrode M and another as the measuring electrode N, and supply power so that the measuring electrode M and the measuring electrode N form a closed measurement loop, thereby obtaining initial observation data in this state;

[0019] According to the above method, all detection electrodes in the in-hole detection cables and the out-of-hole detection electrodes in the first hole are traversed and observed, thereby obtaining initial observation data based on the first hole;

[0020] According to the observation method based on the initial observation data of the first hole, the corresponding initial observation data of the remaining holes are obtained in sequence.

[0021] In some embodiments, the inversion water exploration method further includes:

[0022] The initial observation data screening step is used to calculate the initial observation data based on each well obtained in the initial observation data obtaining step according to the following calculation formula of the geometric factor G, and to eliminate the corresponding initial observation data when G exceeds a preset value to form the detection observation data:

[0023] AM, AN, BM to BN represent the distances between the power supply electrodes and the measuring electrodes; AM', AN', BM' to BN' represent the distances between the virtual electrode points of the power supply electrodes symmetrical about the tunnel face and the measuring electrodes.

[0024] In some embodiments,

[0025] The preset value is 3000.

[0026] In some embodiments, the inversion water exploration method further comprises:

[0027] Establishing a corresponding resistivity initial model and polarizability initial model according to the detection observation data, and performing conventional electrical inversion based on the resistivity initial model to obtain a resistivity inversion model;

[0028] Establish the objective function of cluster joint inversion of tunnel resistivity and polarizability;

[0029] The tunnel resistivity-polarizability clustering joint inversion objective function is minimized based on the tunnel resistivity-polarizability clustering joint inversion objective function, an inversion equation based on the tunnel resistivity-polarizability clustering joint inversion objective function is constructed, the model parameter increment is updated, and the final inversion result is obtained after iterative inversion.

[0030] In some embodiments,

[0031] The objective function of the tunnel resistivity and polarizability clustering joint inversion is: Φ = Φσ +μΦ η +λ1Φ FCM +λ2Φ log , Φ σ =Φ dσ +β σ Φ mσ , Φ η =Φ dη +β η Φ mη

[0032] Among them, Φ σ is the sum of the resistivity data term and the model term of conventional inversion, Φ η is the sum of the conventional inversion polarizability data term and the model term, μ is the weight parameter of the two balanced resistivity and polarizability models, Φ FCM is the clustering term, λ1 is the parameter that determines the weight of the clustering term applied; Φ log is the boundary constraint term, λ2 is the boundary constraint parameter; β σ and β η is the regularization parameter; Φ dσ is the resistivity data item, Φ mσ is the resistivity model term, Φ dη is the polarizability data item, Φ mη is the polarizability model term.

[0033] In some embodiments,

[0034] Among them, m σ is the resistivity vector of the model, m η is the polarizability vector of the model, v k1 is the first cluster center (resistivity value) of the kth class, v k2 is the second cluster center (polarizability value) of the kth class, and the two are added together according to the weight ξ; represents the membership of the jth unit relative to the kth class; t k The target cluster center provided by the known prior rock physical information is the vector ω=(ω1,ω2,...ω k ) T In the equation, each element parameter ω k The size of is determined by the reliability of the kth prior cluster center; q is the fuzzification factor, which is a constant.

[0035] In some embodiments,

[0036] u is the upper bound of the constraint, M is the number of model parameters; and / or,

[0037] and / or,

[0038] In some embodiments,

[0039] Resistivity model increment Δm σ The inversion equation is:

[0040] Among them, J σ is the resistivity sensitivity matrix, β σ is the damping factor of the resistivity model constraint (constant, set empirically), C is the number of clusters, U k is the membership matrix of the grid belonging to the kth cluster, Δd σ is the resistivity data difference vector, which is the difference between the measured data and the predicted data, m σ is the resistivity, is the resistivity reference model, v k1 is the resistivity cluster center of the kth cluster; and / or,

[0041] The iterative update equation of the polarizability boundary constraint parameter λ2 is:

[0042] Among them, - and ζ + are two intermediate variables respectively. The final calculated ζ is also an intermediate coefficient used to update λ2. γ is a constant.

[0043] In some embodiments,

[0044] Polarizability model increment Δm η The inversion equation is:

[0045] Where,

[0046] X=diag(m1,m2,...m M ), Y=uI-X,

[0047] Among them, J η is the sensitivity matrix of polarizability, Δd η is the difference vector of polarizability observation data, is the difference between polarizability observation data and predicted data, v k2 is the polarizability cluster center of the k-th cluster, and e is an M-dimensional column vector;

[0048] Among them, W d is the data weighting matrix, is the polarizability observation data, d η is the polarizability simulation data, β ηis the damping factor of the polarizability model constraint term, W m is the smooth constraint matrix, m η is the polarizability, is the reference model of polarizability, and u is the upper limit of polarizability.

[0049] The present invention provides a construction method and an inversion water exploration method for a hole-tunnel induced polarization water exploration structure, which have the following beneficial effects:

[0050] By arranging multiple forward boreholes on the tunnel face and arranging detection electrodes in each forward borehole, the limitation of traditional detection means being limited by the limited space of the tunnel is broken through. The detection elements (i.e., detection electrodes) are arranged in the forward boreholes of the tunnel to realize close detection, effectively improve the response of the induced polarization field to the detection target, increase the detection distance, and solve the previous problem that small water-conducting structures in front of the tunnel cannot be detected or clearly detected. In the present invention, the hole-tunnel induced polarization is a quadrupole observation method, using a quadrupole observation array, through in-hole excitation and face reception, it can obtain three-dimensional effective information of the water-conducting structure in front. By distributing the power supply electrode pair and the measurement electrode pair to the forward borehole and the face, the two problems of continuous power supply and measurement of a single metal electrode and simultaneous power supply and measurement of multiple electrodes in the same cable are avoided, and the system interference of electrode polarization and multi-core cable coupling is naturally eliminated fundamentally and naturally, which is suitable for induced polarization fine detection.

[0051] The present invention establishes a clustering constraint term for inversion, performs cluster analysis on the resistivity polarizability, and adds a regularized inversion process, thereby leveraging the advantage of cluster analysis in boundary characterization and achieving fine characterization of the water boundary in front of the tunnel. A joint inversion framework for resistivity and polarizability is established, which implements synchronous inversion of resistivity and polarizability in an inversion objective function, reduces the dependence of polarizability inversion on resistivity inversion results, and ensures the convergence of the inversion process. Boundary constraints are added to the inversion of a three-dimensional polarizability model, and the boundary constraints are integrated into the joint inversion framework, so that the polarizability satisfies the restrictions of its natural boundaries, thereby avoiding the defects of too small values ​​in the polarizability inversion model and data deviation from the actual model. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] FIG1 is a side view schematic diagram of a hole-tunnel induced polarization water exploration structure according to an embodiment of the present invention;

[0053] FIG2 is a schematic front view of the hole-tunnel induced polarization water exploration structure according to an embodiment of the present invention (i.e., viewed from the tunnel face side);

[0054] FIG3 is a schematic diagram of a hole-tunneling induced polarization quadrupole observation method;

[0055] FIG4 is a schematic diagram of the calculation of the geometric factor G;

[0056] FIG5 is a flowchart of a clustered joint inversion method for tunnel-induced polarization resistivity and polarizability according to an embodiment of the present invention;

[0057] FIG6 is a schematic diagram of a geoelectric model when performing numerical simulations according to the present invention;

[0058] FIG7 is a comparison diagram of apparent resistivity imaging results of two methods according to an embodiment of the present invention, wherein a) is the apparent polarizability imaging result of the cluster joint inversion method, and b) is the apparent polarizability imaging result of the traditional sequential inversion method;

[0059] FIG8 is a comparison diagram of apparent polarizability imaging results of two methods according to an embodiment of the present invention, wherein a) is the apparent resistivity imaging result of the cluster joint inversion method, and b) is the apparent resistivity imaging result of the traditional sequential inversion method.

[0060] The reference numerals indicate:

[0061] 1. Tunnel cavity; 2. Forward drilling; 5. Power supply electrode A; 6. Power supply electrode B; 7. Measuring electrode M; 8. Measuring electrode N. DETAILED DESCRIPTION

[0062] 1 to 8 , according to an embodiment of the present invention, a construction method of a hole-tunnel induced polarization water exploration structure is provided, comprising the following steps:

[0063] Multiple forward drill holes 2 are arranged at intervals in the outer edge area of ​​the tunnel face;

[0064] An in-hole detection cable is respectively arranged in each of the forward boreholes 2, each of the in-hole detection cables has a plurality of detection electrodes, and each detection electrode in each of the in-hole detection cables is respectively configured as a power supply electrode A5 and a power supply electrode B6;

[0065] A plurality of out-of-hole detection electrodes are arranged in an array in an area outside the area occupied by each of the forward boreholes 2 on the tunnel face, and each of the out-of-hole detection electrodes is configured as a measuring electrode M7 and a measuring electrode N8;

[0066] The power supply electrodes A5 and B6 form a power supply closed loop, and the measurement electrodes M7 and N8 form a measurement closed loop.

[0067] In this technical solution, by arranging multiple forward boreholes 2 on the tunnel face and arranging detection electrodes in each forward borehole 2, the limitation of traditional detection means being limited by the limited space of the tunnel is broken through. The detection elements (i.e., detection electrodes) are arranged in the forward boreholes 2 of the tunnel to realize close detection, effectively improve the response of the induced polarization field to the detection target, increase the detection distance, and solve the previous problem that small water-conducting structures in front of the tunnel cannot be detected or detected clearly. In the present invention, the hole-tunnel induced polarization is a quadrupole observation method, using a quadrupole observation array, through excitation in the hole and reception at the face, three-dimensional effective information of the water-conducting structure in front can be obtained. By dispersing the power supply electrode pair and the measurement electrode pair to the forward borehole and the face, the two problems of continuous power supply and measurement of a single metal electrode and simultaneous power supply and measurement of multiple electrodes in the same cable are avoided, and the system interference of electrode polarization and multi-core cable coupling is naturally eliminated fundamentally, which is suitable for fine detection of induced polarization.

[0068] According to an embodiment of the present invention, there is also provided an inversion water exploration method for a hole-tunnel induced polarization water exploration structure formed based on the construction method of the hole-tunnel induced polarization water exploration structure, comprising:

[0069] The initial observation data acquisition step is used to obtain the induced polarization data of the hole-tunnel induced polarization water exploration structure, using the following method:

[0070] defining any one of the plurality of forward boreholes as a first borehole, selecting one of the detection electrodes in the borehole detection cable in the first borehole as a power supply electrode A and the other as a power supply electrode B, and supplying power so that the power supply electrode A and the power supply electrode B form a power supply closed loop, wherein the power supply electrode A is located between the tunnel face and the power supply electrode B;

[0071] Select one of the plurality of out-of-hole detection electrodes as the measuring electrode M and another as the measuring electrode N, and supply power so that the measuring electrode M and the measuring electrode N form a closed measurement loop, thereby obtaining initial observation data in this state;

[0072] According to the above method, all detection electrodes in the in-hole detection cables and the out-of-hole detection electrodes in the first hole are traversed and observed, thereby obtaining initial observation data based on the first hole;

[0073] According to the observation method based on the initial observation data of the first hole, the corresponding initial observation data of the remaining holes are obtained in sequence.

[0074] Specifically, by traversing and coordinating the detection electrodes (power supply electrode pairs) in each forward borehole 2 with the detection electrodes (measurement electrode pairs) on the tunnel face, it is possible to fully obtain three-dimensional effective information within a large distance range in front of the tunnel face, realize refined detection, and ensure the accuracy of the detection results.

[0075] In some embodiments, the inversion water exploration method further includes:

[0076] The initial observation data screening step is used to calculate the initial observation data based on each well obtained in the initial observation data obtaining step according to the following calculation formula of the geometric factor G, and to eliminate the corresponding initial observation data when G exceeds a preset value to form the detection observation data:

[0077] Among them, AM, AN, BM to BN represent the distance between each power supply electrode and the measuring electrode respectively; AM', AN', BM' to BN' represent the distance between each power supply electrode and the measuring electrode, which is symmetrical to the virtual electrode point of the tunnel face. Taking the diagram in Figure 4 as an example, the figure only shows the relative distance information between the power supply electrode A and the measuring electrode M on the tunnel face. In the figure, A' is the symmetrical virtual electrode point of the power supply electrode A with respect to the tunnel face, so that the corresponding distances AM and AM' are obtained. The relevant distances of other detection electrodes are the same as this principle and are not described in detail. In a specific embodiment, the preset value is 3000. That is, the observation mode with G greater than 3000 is eliminated, and finally the optimized hole-tunnel induced polarization quadrupole effective observation mode is established. In this technical solution, the data exceeding the preset value is eliminated by the geometric factor, which can reduce a large amount of low signal-to-noise ratio or invalid data, and ensure the accuracy and validity of subsequent data.

[0078] In some embodiments, the inversion water exploration method further comprises:

[0079] Establishing a corresponding resistivity initial model and polarizability initial model according to the detection observation data, and performing conventional electrical inversion based on the resistivity initial model to obtain a resistivity inversion model;

[0080] Establish the objective function of cluster joint inversion of tunnel resistivity and polarizability;

[0081] The tunnel resistivity-polarizability clustering joint inversion objective function is minimized based on the tunnel resistivity-polarizability clustering joint inversion objective function, an inversion equation based on the tunnel resistivity-polarizability clustering joint inversion objective function is constructed, the model parameter increment is updated, and the final inversion result is obtained after iterative inversion.

[0082] Specifically, the objective function of the tunnel resistivity and polarizability clustering joint inversion is: Φ = Φ σ +μΦ η +λ1Φ FCM +λ2Φ log , Φ σ =Φ dσ +β σ Φmσ , Φ η =Φ dη +β η Φ mη

[0083] Among them, Φ σ is the sum of the resistivity data term and the model term of conventional inversion, Φ η is the sum of the conventional inversion polarizability data item and the model item, μ is the weight parameter for balancing the two sets of resistivity and polarizability models, and in this invention, μ=1 is set, indicating that resistivity and polarizability have the same weight in the inversion data item model item. FCM is the clustering term that affects the clustering behavior of the two groups of rock physics models of resistivity and polarizability in inversion, λ1 is the parameter that determines the weight of the clustering term applied; Φ log is the boundary constraint term, λ2 is the boundary constraint parameter; the three-dimensional polarizability model is constrained during the inversion process; β σ and β η is the regularization parameter, which balances the weights of the data term and model term in the resistivity model and polarizability model respectively; Φ dσ is the resistivity data item, Φ mσ is the resistivity model term, Φ dη is the polarizability data item, Φ mη is the polarizability model term.

[0084] In this technical solution, a clustering constraint term for inversion is established, and a cluster analysis is performed on the resistivity polarizability and a regularized inversion process is added, which gives full play to the advantage of cluster analysis in boundary characterization and realizes the fine characterization of the water body boundary in front of the tunnel; a joint inversion framework for resistivity and polarizability is established to realize the synchronous inversion of resistivity and polarizability in one inversion objective function, reducing the dependence of polarizability inversion on the resistivity inversion results and ensuring the convergence of the inversion process; boundary constraints are added to the inversion of the three-dimensional polarizability model, and the boundary constraints are integrated into the joint inversion framework, so that the polarizability meets the restrictions of its natural boundaries, thereby avoiding the defects of the polarizability inversion model being too small and the data deviating from the actual model.

[0085] In the clustering items,

[0086] Among them, m σ is the resistivity vector of the model, m η is the polarizability vector of the model, v k1 is the first cluster center (resistivity value) of the kth class, v k2 is the second cluster center (polarizability value) of the kth class. The two are added together according to the weight ξ. According to statistical principles, when this item is minimum, it is considered that all units of the model have been correctly classified. represents the membership of the jth unit relative to the kth class; t kThe target cluster center provided by the known prior rock physical information is the vector ω=(ω1,ω2,...ω k ) T In the equation, each element parameter ω k The size of depends on the reliability of the kth prior cluster center. If the reliability of the cluster center provided by the kth prior information is low, ω is appropriately reduced. k The value of ; q is the fuzzification factor, which is a constant, usually 2.

[0087] In some embodiments,

[0088] u is the upper boundary of the constraint. Considering that the polarizability of the water body in front of the tunnel is generally 0.3, in the present invention, for tunnel drilling induced polarization detection, u=0.3 is set, and M is the number of model parameters. Specifically, in specific applications, forward and inversion are performed through discretization methods such as finite element method, and the model is divided into individual grids. M is the number of all grids, which is also the total number of model parameters of each grid.

[0089] The initial value of λ2 is:

[0090] Among them, W d is the data weighting matrix, is the polarizability observation data, d η is the polarizability simulation data (also called predicted data), β η is the damping factor of the polarizability model constraint (constant, set empirically), W m is the smooth constraint matrix, m η is the polarizability, is the reference model of polarizability, u is the upper limit of polarizability;

[0091] Membership and cluster center v k1 、v k2 The inversion equations are:

[0092] and / or,

[0093] and / or,

[0094] Resistivity model increment Δm σ The inversion equation is:

[0095] Among them, J σ is the resistivity sensitivity matrix, β σ is the damping factor of the resistivity model constraint (constant, set empirically), C is the number of clusters, U kis the membership matrix of the grid belonging to the kth cluster, Δd σ is the resistivity data difference vector, which is the difference between the measured data and the predicted data, m σ is the resistivity, is the resistivity reference model, v k 1 is the resistivity cluster center of the kth cluster; and / or,

[0096] In some embodiments,

[0097] The iterative update equation of the polarizability boundary constraint parameter λ2 is:

[0098] Among them, - and ζ + They are two intermediate variables respectively. The final calculated ζ is also an intermediate coefficient used to update λ2. γ is a constant, generally with a value of 0.925.

[0099] Polarizability model increment Δm η The inversion equation is:

[0100] Where,

[0101] X=diag(m1,m2,...m M ), Y=uI-X,

[0102] Among them, J η is the sensitivity matrix of polarizability, Δd η is the difference vector of polarizability observation data, is the difference between polarizability observation data and predicted data, v k2 is the polarizability cluster center of the kth cluster, and e is an M-dimensional column vector.

[0103] The technical solution of the present invention is further described below with reference to a specific embodiment:

[0104] The water exploration method of the present invention can generally include two parts: data measurement and data processing and imaging. The main contents are as follows:

[0105] (1) Data measurement

[0106] In a specific example, as shown in Figures 1 and 2, three 65m long forward boreholes 2 are constructed in the tunnel face, and horizontal cables (i.e., the borehole detection cables mentioned above, the same below) are laid in the boreholes. 32 electrodes (i.e., the aforementioned detection electrodes) are laid on each cable at a spacing of 2m. 25 electrode potentials (i.e., the out-of-hole detection electrodes mentioned above) are laid on the face (i.e., the tunnel face mentioned above), and each electrode point is connected to a cable. The above operation is called "wiring". It should be noted that the spacing between the electrodes in the above-mentioned boreholes can be adjusted according to actual detection needs. If a smaller spacing such as 1m is used, the detection resolution will be improved accordingly, otherwise it will be reduced. The number of electrodes laid in each borehole and face can be adjusted according to actual needs, and generally shall not exceed 32.

[0107] After wiring is completed, an observation pattern is generated according to the established observation method. Detection uses the hole-tunnel induced polarization quadrupole observation method, as shown in Figure 3. Taking one data acquisition example, power supply electrode A5 and power supply electrode B6 are placed in the same borehole, with power supply electrode A5 positioned closer to the tunnel face relative to power supply electrode B6. Measurement electrodes M7 and N8 are placed on the tunnel face, and their relative positions remain unchanged. When generating the observation pattern, all electrode potentials are traversed according to the relative position rules described above. Considering the presence of three boreholes on the tunnel face, a total of 446,400 observation data can be generated, forming a preliminary hole-tunnel induced polarization observation pattern (the data obtained are also known as the initial observation detection data). However, this data contains a large amount of low signal-to-noise ratio or invalid data, so further screening is required.

[0108] The geometric factor calculation is performed on each data in the generated preliminary observation pattern. The calculation rules refer to the above formula (1) and Figure 4. Then, the data in the observation pattern are screened according to the geometric factor. The observation data with a geometric factor greater than 3000 are eliminated. The remaining observation data constitute the final hole-tunnel induced polarization observation pattern.

[0109] After completing wiring, observation mode generation and data screening, connect the cable to the host, power on the host and connect it to the main control computer before starting data acquisition. After data measurement is completed, data processing and imaging can begin.

[0110] (2) Data processing and imaging

[0111] (1) Establish a geoelectric model of the low-resistance body in front of the tunnel and perform forward modeling on the geoelectric model to obtain two sets of observation data (resistivity observation data), (polarizability observation data), establish two sets of initial models corresponding to the two sets of observation data spaces Perform conventional electrical inversion on the initial resistivity model. Conventional electrical forward and inversion are well known in the industry and will not be described in detail here.

[0112] (2) Calculation of polarizability boundary constraint parameters The initial value of the cluster center vector is set based on experience

[0113] (3) Calculate the membership degree of each unit in the model Calculate the cluster center vector of each cluster The present invention sets ξ = 1, that is, the resistivity and polarizability have the same weight in the membership calculation. The present invention sets q = 2; the parameter ω k According to the prior cluster center t k The reliability of k =1;

[0114] (4) Calculate the sensitivity matrix of resistivity inversion in the nth iteration and the sensitivity matrix for polarizability inversion The sensitivity calculation is mainly based on the reciprocity criterion, and the nth iteration resistivity model increment is obtained respectively. and polarizability model increment Update resistivity model In the present invention, β σ =0.05, indicating that the weight of the model term in the resistivity inversion term is 0.05; λ1 = 0.01, indicating that the weight of the clustering term applied is 0.01;

[0115] (5) Update the polarizability boundary constraint parameter λ2. The parameter γ is used to prevent the value of each unit in the model from reaching the boundary exactly so that the logarithmic constraint iteration can continue. In this invention, γ is set to 0.925.

[0116] (6) Obtain the polarizability model increment And update the polarizability model The present invention provides η =0.1, indicating that the weight of the model term in the polarizability inversion term is 0.1; X = diag(m1,m2,...m M ), Y=uI-X.

[0117] As a typical implementation:

[0118] (1) The geoelectric model of the low-resistance body in front of the tunnel is established as shown in Figure 5. In the model, the low-resistance water body is located 5m in front of the tunnel and has a size of 2*3*2. Four forward boreholes are laid in front of the tunnel, each with 20 electrodes and a borehole spacing of 1m. A four-hole joint observation method is used to collect two sets of observation data: apparent resistivity and apparent polarizability within 20m in front of the tunnel. The inversion area is 8*8*20m;

[0119] (2) With the center of the tunnel face as the origin, a three-dimensional coordinate system is established in front of the tunnel to establish the initial resistivity model and the initial model of polarizability And the corresponding reference model Calculate the smoothness matrix W of the model m and the data weight matrix W d ;

[0120] (3) Initial resistivity model Perform several resistivity linear inversions and use the inversion results as the initial resistivity model for the next step of resistivity-polarizability clustering joint inversion.

[0121] (4) Initial model of polarizability Forward modeling to obtain initial prediction data of polarizability And substitute into formula (1) to calculate the polarizability boundary constraint parameter The initial value of

[0122] (5) Set the initial cluster center vector is the first initial cluster center (resistivity value) of the kth class, is the second initial cluster center (polarizability value) of the kth class;

[0123] (6) Start cluster joint inversion iteration and calculate the membership degree of each unit in the model The cluster center vector of each cluster is calculated by formula (3):

[0124] (7) Calculate the sensitivity matrix of resistivity inversion in the nth iteration and the sensitivity matrix for polarizability inversion Among them J σ The sensitivity matrix corresponding to the apparent resistivity data and the resistivity model is calculated using traditional methods. ηi,j is the matrix J η The element in row i and column j in , σ bj is the background conductivity of the jth unit, is the potential prediction data of the i-th unit when there is no excitation polarization effect, is the total potential prediction data under the polarization effect of the ith unit;

[0125] (8) Obtain the nth iteration resistivity model increment Update resistivity model

[0126] (9) Update polarizability boundary constraint parameters The value of . Get the polarizability model increment And update the polarizability model

[0127] (10) Updated resistivity model and polarizability model Forward modeling is performed to obtain the nth resistivity prediction data and polarizability prediction data Difference the two sets of observed data of resistivity and polarizability with the corresponding predicted data, and calculate the residual

[0128] (11) Calculate the fitting error RMS and RMS_IP of the nth iteration. If the convergence condition is not met, continue to loop steps (6) to (11). If the convergence condition is met, output the imaging result.

[0129] This example compares the imaging results of the clustered joint inversion method with those of the traditional sequential inversion method. After performing 40 individual resistivity inversions on the initial model, the clustered joint inversion method was performed 60 times. The inversion results are shown in Figures 7a and 8a). The traditional sequential inversion method was then followed by 60 individual resistivity and polarizability inversions. The inversion results are shown in Figures 7b and 8b.

[0130] Figures 7 and 8 respectively output and image the apparent polarizability and apparent resistivity of the y=0 section of the two inversion results. Comparing the imaging results of the two methods, it can be seen that the induced polarization clustering joint inversion method of the present invention can accurately depict the boundary of the water body in front of the tunnel.

[0131] It will be understood by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0132] The present invention is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device produce a device for implementing the functions specified in one or more processes in the flowchart and / or one or more boxes in the block diagram.

[0133] These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce a product including an instruction device that implements the functions specified in one or more processes in the flowchart and / or one or more boxes in the block diagram.

[0134] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, so that the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in one or more processes in the flowchart and / or one or more boxes in the block diagram.

[0135] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

[0136] Although the above describes the specific embodiments 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 any creative work are still within the scope of protection of the present invention.

Claims

1. A construction method for a hole-tunnel induced polarization water exploration structure, characterized in that: The steps include: Multiple forward boreholes are arranged at intervals in the outer edge area of ​​the tunnel face; An in-hole detection cable is respectively arranged in each of the forward boreholes, each of the in-hole detection cables has a plurality of detection electrodes, and each detection electrode in each of the in-hole detection cables is respectively configured as a power supply electrode A and a power supply electrode B; A plurality of out-of-hole detection electrodes are arranged in an array on the area outside the area occupied by each of the forward boreholes on the tunnel face, and each of the out-of-hole detection electrodes is configured as a measuring electrode M and a measuring electrode N; The power supply electrodes A and B form a power supply closed loop, and the measuring electrodes M and N form a measurement closed loop.

2. An inversion water exploration method of a hole-tunnel induced polarization water exploration structure formed based on the construction method of the hole-tunnel induced polarization water exploration structure according to claim 1, characterized in that: include: The initial observation data acquisition step is used to obtain the induced polarization data of the hole-tunnel induced polarization water exploration structure, and adopts the following method: Define any one of the plurality of forward boreholes as a first borehole, select one of the detection electrodes in the borehole detection cable in the first borehole as a power supply electrode A and the other as a power supply electrode B, and supply power so that the power supply electrode A and the power supply electrode B form a power supply closed loop, wherein the power supply electrode A is between the tunnel face and the power supply electrode B; Select one of the plurality of out-of-hole detection electrodes as the measuring electrode M and another as the measuring electrode N, and supply power so that the measuring electrode M and the measuring electrode N form a measuring closed loop, thereby obtaining initial observation data in this state; According to the above method, all detection electrodes in all in-hole detection cables in the first hole and the out-of-hole detection electrodes are observed, so as to obtain initial observation data based on the first hole; According to the observation method based on the initial observation data of the first hole, the corresponding initial observation data of the remaining holes are obtained in sequence.

3. The inversion water exploration method according to claim 2, characterized in that: Also includes: The initial observation data screening step is used to calculate the initial observation data based on each hole obtained in the initial observation data acquisition step according to the following calculation formula of the geometric factor G, and to eliminate the corresponding initial observation data when the G exceeds a preset value to form the detection observation data: Among them, AM, AN, BM to BN represent the distance between each power supply electrode and the measuring electrode respectively; AM', AN', BM' to BN' represent the distance between the virtual electrode point position of each power supply electrode symmetrical about the tunnel face and the measuring electrode respectively.

4. The inversion water exploration method according to claim 3, characterized in that: The preset value is 3000.

5. The inversion water exploration method according to claim 3, characterized in that: Also includes: Establishing a corresponding resistivity initial model and a polarizability initial model according to the detection observation data, and performing conventional electrical inversion based on the resistivity initial model to obtain a resistivity inversion model; Establish the objective function of cluster joint inversion of tunnel resistivity and polarizability; Based on the tunnel resistivity polarizability clustering joint inversion objective function, the tunnel resistivity polarizability clustering joint inversion objective function is minimized, an inversion equation based on the tunnel resistivity polarizability clustering joint inversion objective function is constructed, the model parameter increment is updated, and the final inversion result is obtained after iterative inversion.

6. The inversion water exploration method according to claim 5, characterized in that: The objective function of the tunnel resistivity and polarizability clustering joint inversion is: F=F σ +μΦ η +λ1Φ FCM +λ2Φ log ,F σ =Φ dσ +b σ F mσ ,F η =Φ dη +b η F mη Among them, Φ σ is the sum of the resistivity data term and the model term of the conventional inversion, Φ η is the sum of the conventional inversion polarizability data term and the model term, μ is the weight parameter of the two sets of balanced resistivity and polarizability models, Φ FCM is the clustering term, λ1 is the parameter that determines the weight of the clustering term applied; Φ log is the boundary constraint term, λ2 is the boundary constraint parameter; β σ With β η is the regularization parameter; Φ dσ is the resistivity data item, Φ mσ is the resistivity model term, Φ dη is the polarizability data term, Φ mη is the polarizability model term.

7. The inversion water exploration method according to claim 6, characterized in that: Among them, m σ is the resistivity vector of the model, m η is the polarizability vector of the model, v k1 is the first cluster center (resistivity value) of the kth class, v k2 is the second cluster center (polarizability value) of the kth class, and the two are added according to the weight ξ; represents the membership of the jth unit to the kth class; t k The target cluster center provided by the known prior rock physical information, vector ω=(ω1,ω2,...ω k ) T In the equation, each element parameter ω k The size of depends on the reliability of the kth prior cluster center; q is the fuzzification factor, which is a constant.

8. The inversion water exploration method according to claim 7, characterized in that: u is the upper bound of the constraint, M is the number of model parameters; and / or, and / or, 9. The inversion water exploration method according to claim 8, characterized in that: Resistivity model increment Δm σ The inversion equation is: Among them, J σ is the resistivity sensitivity matrix, β σ is the damping factor of the resistivity model constraint (constant, set empirically), C is the number of clusters, U k is the membership matrix of the grid belonging to the kth cluster, Δd σ is the resistivity data difference vector, which is the difference between the measured data and the predicted data, m σ is the resistivity, is the resistivity reference model, v k1 is the resistivity cluster center of the kth cluster; and / or, The iterative update equation of the polarizability boundary constraint parameter λ2 is: ζ=min(ζ - ,g + ),λ2=λ2[1-min(γ,ζ)], Among them, - and + are two intermediate variables respectively. The final calculated ζ is also an intermediate coefficient used to update λ2; γ is a constant.

10. The inversion water exploration method according to claim 9, characterized in that: Polarizability model increment Δm η The inversion equation is: In the formula, X=diag(m1,m2,...m M ), Y=uI-X, Among them, J η is the sensitivity matrix of polarizability, Δd η is the difference vector of polarizability observation data, is the difference between polarizability observation data and predicted data, v k2 is the polarizability cluster center of the k-th cluster, and e is an M-dimensional column vector; Among them, W d is the data weighting matrix, is the observed data of polarizability, d η is the polarizability simulation data, β η is the damping factor of the polarizability model constraint term, W m is the smooth constraint matrix, m η is the polarizability, is the reference model of polarizability, and u is the upper limit of polarizability.

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