Fine fourth-century three-dimensional geological modeling integration method

Abstract

The invention discloses a refined fourth-century three-dimensional geological modeling integration method which comprises the steps that basic geological data and drilling data of a research area are acquired, and the basic geological data comprise bedrock geological data and fourth-century geological data; the drilling data is modeled by a triangulated irregular network, and the basic unit of the triangulated irregular network is GTP; performing standardization processing on the drilling data; carrying out fourth stratigraphic division on the research area according to the basic geological data; dEMs of stratum interfaces are sequentially established from the earth surface to the underground according to the drilling data, sewing processing is conducted on the adjacent DEMs belonging to the same stratum, and a three-dimensional stratum model based on the multiple layers of DEMs is formed; dividing the GTP into TEN, and according to the three-dimensional stratum model based on the multilayer DEM, taking the TEN as a basic voxel, and constructing a fourth-century three-dimensional geologic model based on MD-GTP-TEN; the model constructed by the invention can express the geologic body more accurately and perform spatial analysis more efficiently.

Description

Technical Field

[0001] The present invention relates to the technical field of three-dimensional geological modeling, and in particular to a refined Quaternary three-dimensional geological modeling integration method. Background Art

[0002] Ground subsidence is a slow-changing environmental geological disaster caused by the consolidation and compression of loose soil, which leads to the reduction of ground elevation. It has the characteristics of large impact range, long duration, slow development time, complex cause mechanism and great difficulty in prevention and control, and has caused many problems worldwide. Since the Quaternary geological period covers the period from about 2.5 million years ago to the present, geological events such as climate change, tectonic activities and paleontological evolution have had a significant impact on the earth's surface. Through the Quaternary 3D geological modeling technology, computer technology is used to combine spatial information management, geological interpretation, spatial analysis and prediction, geostatistics, entity content analysis and 3D graphics visualization tools, which can accurately express the spatial structure and geological structure of the strata during this period, and provide a new perspective for understanding the changes in the earth's environment and the prevention of geological disasters.

[0003] With the continuous expansion and deepening of the research and application of 3D modeling technology in the field of geology, more than 20 spatial modeling theories have emerged. These theories can be divided into surface models, entity models and hybrid models. Surface models mainly describe objective things by simulating the surface or interface of entities and then enclosing them into a body. They focus on the representation of the surface of 3D entities. The advantages of surface models are small data volume, fast modeling speed, and convenient 3D visualization and model update. However, the disadvantage is that it cannot truly express the geometric topological relationship and internal attributes of entities in 3D space, so it is difficult to query and analyze 3D space. Commonly used surface models include boundary representation (B-rep) model, wire frame model, triangulated irregular network (TIN) model, grid model, section model and multi-layer digital elevation model (DEM).

[0004] The solid model uses a three-dimensional entity to describe a three-dimensional geological body, and uses three-dimensional unit entities, such as tetrahedrons or hexahedrons, to construct the entire three-dimensional geological body. The solid model focuses on the representation of three-dimensional space bodies and is a true three-dimensional model. Its advantage is that it describes three-dimensional topological relationships and is suitable for spatial query and analysis. However, its disadvantages are complex data structure, large storage space occupation, slow modeling speed, and difficulty in model updating. Commonly used solid models include constructive solid geometry (CSG) model, octree model, tetrahedron model (Tetrahedra-based Element Network, TEN), block model, generalized triprism (GTP) model, solid model, etc.

[0005] The hybrid model is a method of modeling by combining two or more models. It aims to integrate the advantages of surface models and solid models, regular voxels and irregular voxels, give full play to their respective strengths and make up for their weaknesses. However, it is relatively difficult to implement in technology and still needs to be further improved. At present, a variety of hybrid models have been proposed, such as TIN-CSG hybrid model, TIN-Octree hybrid model, Wire Frame-Block hybrid model, Octree-TEN hybrid model and GTP-TEN hybrid model. In addition, the use of borehole data, geological profile data and expert experience for three-dimensional geological modeling is also a hot topic of research at home and abroad. Due to the complexity and variability of geological conditions, most of the current modeling methods ignore the knowledge reasoning rules when constructing strata, and do not consider the impact of complex geological structures such as faults on modeling. This makes the scope of application of existing models limited, and it is difficult to construct a three-dimensional model that can meet all geological conditions. Therefore, it is necessary to propose a refined Quaternary three-dimensional geological modeling integration method to solve the above problems. Summary of the invention

[0006] The present invention provides a refined Quaternary three-dimensional geological modeling integrated method, which can express geological bodies more accurately and perform spatial analysis more efficiently.

[0007] The present invention provides a refined Quaternary three-dimensional geological modeling integrated method, comprising:

[0008] Step 1: Obtain basic geological data and drilling data of the study area, wherein the basic geological data includes bedrock geological data and Quaternary geological data; the drilling data is modeled using an irregular triangulated network, and the basic unit of the irregular triangulated network is GTP;

[0009] Step 2: standardize the drilling data;

[0010] Step 3: divide the Quaternary stratigraphic units of the study area according to basic geological data;

[0011] Step 4: DEMs of stratum interfaces are established from the surface to the underground in sequence according to the drilling data, and adjacent DEMs belonging to the same stratum are stitched to form a three-dimensional stratum model based on multi-layer DEMs;

[0012] Step 5: Divide the GTP into TENs, and construct a Quaternary three-dimensional geological model based on MD-GTP-TEN according to the three-dimensional stratigraphic model based on the multi-layer DEM and using TENs as basic volume elements.

[0013] Furthermore, step 2 includes:

[0014] The spatial data in the drilling data are unified into the CGCS2000 coordinate system;

[0015] Draw the Quaternary geological profile according to the original borehole stratification information in the drilling data, and make stratification comparison between boreholes in combination with the corresponding lithology description and test results;

[0016] Based on the stratification comparison results between the boreholes, an initial standard stratification is assigned to each stratum on the Quaternary geological cross section;

[0017] By comparing multiple sections, the drilling stratification is modified and the standard stratification results are adjusted to obtain a unified standard stratum;

[0018] Other boreholes are standardized one by one according to the standard formation.

[0019] Furthermore, step four includes:

[0020] Determine the boundary range of the modeling area and the stratigraphic number corresponding to each intersection point;

[0021] Interpolation calculation is performed according to the intersection points. Based on the triangulation generation algorithm, an irregular triangulated network TIN model is constructed to organize the discrete points on each sub-TIN that constitutes the stratum interface or fault, the intersecting arcs of each sub-TIN, and establish the topological relationship between TIN and arcs, and between the stratum interface and each sub-TIN;

[0022] The Delaunay TIN construction method was used to model each sub-TIN surface, and the shortest diagonal method was used to model the fault sub-surface;

[0023] Select inverse distance weighting, moving surface fitting and spatial kriging interpolation methods to organize the interpolation points and establish a unified plane grid point;

[0024] When the stratum interfaces intersect, determine whether each triangular unit of the adjacent stratum interfaces intersects; if there is an intersection, find the intersection line of the two triangular units; delete the redundant triangular unit parts according to the topological relationship, and then reconstruct the remaining polygons.

[0025] Furthermore, step five includes:

[0026] S1, extract a triangle from the Delaunay triangulation network of the ground surface, and set this triangle as the upper triangle of the first generalized triangular prism;

[0027] S2, according to the stratigraphic numbers of the three vertices of the upper triangle, a new triangle is extended downward along the borehole according to the reasoning rules of three-dimensional structural knowledge. The new triangle is called the lower triangle;

[0028] S3, construct a generalized triangular prism according to the correspondence between the upper triangle and the lower triangle in the triangle bidirectional linked list and the drilling point chain, record the description information of the generalized triangular prism, and set the lower triangle to the upper triangle;

[0029] Repeat S2 and S3 until the vertices of the upper triangle are the bottom points of their respective drilling holes;

[0030] Repeat S1 to S4 until all the triangles of the ground surface TIN are traversed.

[0031] Furthermore, the method also includes a dynamic reconstruction method based on the GTP topology relationship, the steps are as follows:

[0032] Determine the plane equation of the section, determine the positional relationship between each GTP voxel vertex and the plane, and delete all GTP voxels whose vertices are located in the non-retained part of the plane from the linked list;

[0033] Traverse the GTP voxels in the Quaternary 3D geological model based on MD-GTP-TEN, perform dynamic tetrahedral partitioning operations on the remaining GTP voxels, and obtain all GTP voxels to be partitioned;

[0034] Determine the sectioning type and the corresponding reorganization method according to the positional relationship between the vertices of the GTP to be sectioned and the sectioning plane;

[0035] Find the intersection of the cutting plane and GTP;

[0036] According to the reorganization method, the GTP volume element to be sectioned is reorganized into a number of tetrahedral GTP volume elements, and the topological relationship of the Quaternary three-dimensional geological model based on MD-GTP-TEN is updated;

[0037] Invalid and redundant data are eliminated, and the sectioning results are rendered and visualized.

[0038] Furthermore, the method further comprises:

[0039] The real boreholes that were not involved in the construction of the Quaternary 3D geological model based on MD-GTP-TEN were selected for comparative analysis with the virtual boreholes extracted from the corresponding positions in the Quaternary 3D geological model based on MD-GTP-TEN;

[0040] Taking the real borehole as the standard, the differences between the virtual borehole and the real borehole in terms of stratum burial depth and layer thickness are analyzed to reflect the accuracy of the Quaternary 3D geological model based on MD-GTP-TEN.

[0041] Further, including:

[0042] When conducting comparative analysis of the buried depth error of geological roof body between real borehole and virtual borehole at the same location, the error of the buried depth of roof body of a certain layer in the real borehole and the buried depth of roof body corresponding to the virtual borehole is calculated; the buried depth error of roof body of the i-th layer of the borehole is:

[0043] P i =|A vi -A ri |(1)

[0044] Where P i represents the top plate buried depth error of the virtual borehole i-th geological body, A vi represents the top plate depth of the virtual borehole i-th geological body, A ri Represents the top burial depth of the geological body of the i-th layer of the actual borehole;

[0045] The error of the top plate burial depth of the entire borehole is calculated comprehensively as the error of the Quaternary three-dimensional geological model near the borehole; the error of the top plate burial depth of the entire borehole is:

[0046]

[0047] Where P represents the top plate burial depth error of the entire virtual borehole geological body, and n represents the total number of virtual borehole layers involved in the calculation.

[0048] Further, including:

[0049] When conducting a comparative analysis of the layer thickness error between the real borehole and the virtual borehole at the same location, the error between the layer thickness of a layer in the real borehole and the layer thickness corresponding to the virtual borehole is calculated; the layer thickness error of the i-th layer of the borehole is:

[0050] Q i =|D vi -D ri | (3)

[0051] In the formula, Q i represents the layer thickness error of the virtual drilling layer i, D virepresents the layer thickness of the virtual drilling layer i, D ri represents the layer thickness of the i-th layer of the actual drilling;

[0052] The layer thickness error of the entire borehole is calculated comprehensively as the error of the three-dimensional geological model near the borehole; the layer thickness error of the entire borehole is:

[0053]

[0054] Where Q represents the layer thickness error of the entire virtual drilling hole, and n represents the total number of virtual drilling layer layers involved in the calculation.

[0055] The present invention has the following beneficial effects: A refined Quaternary three-dimensional geological modeling integration method of the present invention reduces the difficulty of constructing a Quaternary geological three-dimensional model, and avoids the difficulty and tediousness of cutting and self-decomposition. At the same time, the virtual borehole is determined by the interpolation method, which reduces the difficulty of calculation. In addition, the present invention proposes a reorganization method based on the GPT topological relationship, which supports multiple arbitrary sectioning of a single GTP element, and realizes more complex three-dimensional space analysis functions, such as space excavation and tunneling simulation. This method was applied in Nantong City, and the reliability of the model was verified by sparse drilling data analysis. The construction of the Quaternary three-dimensional geological model reveals the spatial distribution of geological layers and integrates the lithological characteristics of the strata, which can provide assistance for geological activity research and geological disaster prevention. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] In order to more clearly illustrate the technical solution of the present invention, the drawings required for use in the embodiments are briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0057] Figure 1 A flowchart of a refined Quaternary three-dimensional geological modeling integrated method of the present invention;

[0058] Figure 2 It is a schematic diagram of the intersection of stratigraphic triangulation networks;

[0059] Figure 3 Schematic diagram of GTP complete section types and their topological reorganization methods. The shadow represents the section plane. (a) to (h) are 8 types of geological body complete section types and their corresponding reorganization methods.

[0060] Figure 4 This is a statistical diagram of the error frequency of the Quaternary three-dimensional geological model of a certain city; among them, (a) is the error of the buried depth of the top plate of the geological body, and (b) is the error of the layer thickness. DETAILED DESCRIPTION

[0061] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described in conjunction with the specific embodiments of the present invention and the corresponding drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. The technical solutions provided by the embodiments of the present invention are described in detail below in conjunction with the drawings.

[0062] The present invention proposes a new hybrid Quaternary three-dimensional geological modeling method MD-GPT-TEN. A multi-layer DEM model (MD) is used to accurately express the stratigraphic interface, and the stratigraphic structural reasoning and modeling problems are solved according to the stratigraphic structural knowledge reasoning rules, so that the geological model can more truly reflect the actual geological conditions and improve the accuracy of the data. At the same time, the generalized triangular prism GTP is used to reduce the difficulty of geological body model construction and avoid the problems of cutting and self-decomposition difficulties of other volume element models. Each GTP is composed of three TEN models, which can fully express the layered geological body without changing the structure of the original GTP model, so that the side non-planar situation can be handled to support three-dimensional space operations. On the basis of constructing the Quaternary three-dimensional geological model, the cutting algorithm is improved, and a new GTP reorganization method and composite cutting algorithm that can support multiple arbitrary cutting are proposed to realize complex three-dimensional space analysis functions. The significance of the MD-GPT-TEN hybrid model is to provide a more comprehensive and flexible Quaternary three-dimensional geological modeling method, which can more accurately express the geological body and more efficiently perform spatial analysis, and provide powerful tools and support for geological structure research and geological disaster prevention.

[0063] See also Figure 1 The embodiment of the present invention provides a refined Quaternary three-dimensional geological modeling integrated method, comprising:

[0064] Step 1: Obtain basic geological data and drilling data of the study area, wherein the basic geological data include bedrock geological data and Quaternary geological data; the drilling data is modeled using an irregular triangulated network, and the basic unit of the irregular triangulated network is GTP.

[0065] In this example, the study area is located in a certain city, and the study area includes four districts with a total area of ​​about 800km 2 The overall terrain of the area is flat, with very small surface undulations. The terrain elevation is generally between 2.0-6.5m, and it is slightly inclined from northwest to southeast. The Quaternary strata in the study area mainly include clay, gravel powder, clay, coarse sand and other lithological types, which are characterized by small sedimentary thickness, complex genetic types, and are significantly controlled by bedrock structure and landforms.

[0066] Among them, the bedrock geological data include: 1:50,000 bedrock geological map of a certain city; the Quaternary geological data include: 1:50,000 Quaternary geological map of a certain city, Quaternary geological profile, and 1:50,000 lithofacies paleogeographic map of a certain city in the characteristic era.

[0067] The borehole data are the basis for modeling the stratigraphic structure model. The borehole model in this study area includes 81 slot boreholes and 28 Quaternary geological boreholes, and is modeled using an irregular triangulated network, in which the basic unit is GTP.

[0068] Step 2: Standardize the drilling data.

[0069] In order to improve the versatility and utilization of Quaternary geological data, the present invention performs standardization processing on the data. The standardization processing of drilling data includes the following steps:

[0070] First, in order to facilitate the spatial positioning, splicing and registration of geographic information, the spatial data in the drilling data are unified into the CGCS2000 coordinate system;

[0071] Secondly, since the information of a single borehole only shows the geological conditions in a point-like manner, the geological conditions can be analyzed as a whole by drawing a profile. Based on the original borehole stratification information in the borehole data, a Quaternary geological profile is drawn, and combined with the corresponding lithology description and test results, stratification comparison between boreholes is performed;

[0072] Secondly, establish standard stratification. According to the stratification comparison results between the boreholes, assign initial standard stratification to each stratum on the Quaternary geological profile;

[0073] Then, by comparing multiple sections, the drilling stratification is modified and the standard stratification results are adjusted to obtain a unified standard stratum;

[0074] Finally, borehole standardization is performed. According to the standard stratum, other boreholes are standardized one by one and stored in the database as data sources.

[0075] Step three, divide the Quaternary stratigraphic units in the study area based on basic geological data.

[0076] The study of the Quaternary stratigraphic structure needs to be based on the comprehensive foundation of the division of the Quaternary stratigraphy and the Quaternary controlling sections. Strata are diverse in characteristics and attributes, and each characteristic or attribute can be used as the basis for stratigraphic division. Therefore, the categories of stratigraphic division are also very diverse, including lithostratigraphy, chronostratigraphy, biostratigraphy, sequence stratigraphy, etc.

[0077] When dividing the Quaternary strata in the study area, the following considerations are mainly used: first, the lithological characteristics of the sediments, including color, structure and texture; second, the facies change characteristics of the sediments, as well as the sedimentary cycles, sedimentary discontinuities and other signs of the sediments; in addition, a comprehensive analysis is also required based on the sediment outcrop locations, distribution characteristics and micro-geomorphological characteristics of the survey points; finally, based on regional geology and age, direct field stratification can be better carried out.

[0078] Step 4: DEM of the stratigraphic interface is established from the surface to the underground according to the drilling data, and adjacent DEMs belonging to the same stratigraphic layer are stitched to form a three-dimensional stratigraphic model based on multi-layer DEM.

[0079] Specifically, step four includes:

[0080] Determine the boundary range of the modeling area and the stratigraphic number corresponding to each intersection point;

[0081] Interpolation calculation is performed based on the intersection points. Based on triangulation generation algorithms such as the Advancing Front Technique (AFT) and Deaulany, an irregular triangulated network (TIN) model is constructed to organize the discrete points on each sub-TIN that constitutes the stratum interface or fault, the intersecting arcs of each sub-TIN, and establish the topological relationship between TIN and arcs, and between the stratum interface and each sub-TIN.

[0082] The Delaunay TIN construction method was used to model each sub-TIN surface, and the shortest diagonal method was used to model the fault sub-surface;

[0083] Select various spatial interpolation methods such as inverse distance weighting, moving surface fitting and spatial kriging interpolation to organize the interpolation points and establish a unified plane grid point;

[0084] For the case where the stratum interfaces intersect, such as Figure 2 As shown, the stratum interface A and the bottom interface B intersect, and it is determined whether each triangular unit of the adjacent stratum interfaces intersects; if there is an intersection, the intersection line of the two triangular units is obtained; according to the topological relationship, the redundant triangular unit parts are deleted, and then the remaining polygons are triangulated and reconstructed.

[0085] The three-dimensional stratigraphic model based on multi-layer DEM adds the data of manual editing and processing of stratigraphic layers and faults. The existence of faults increases the constraint relationship between the discrete points of the orifice, and the fault line needs to be constrained. The constrained Delaunay triangulation algorithm is adopted to make the model more reasonable; the TIN model is established by fragmentation and the fault model is established by layering using the shortest diagonal method for faults, so that the data distribution of each modeling unit is simple, overcoming the need to consider the complex algorithm of constructing the TIN model when there are spatial overlaps or overlapping sampling points; the topological relationship between the volume, stratigraphic interface or fault plane, TIN and arc segment is effectively established, which brings convenience to the subsequent model analysis operation.

[0086] Step 5: Divide the GTP into TENs, and construct a Quaternary three-dimensional geological model based on MD-GTP-TEN according to the three-dimensional stratigraphic model based on the multi-layer DEM and using TENs as basic volume elements.

[0087] In the three-dimensional modeling of Quaternary geology, the voxel model can represent various spatial entities inside the geological body. For complex geological conditions, the GTP voxel can be deformed to simulate complex geological structures such as faults, bifurcations and pinch-outs, which better fits the spatial distribution characteristics of the strata and ensures the consistency of the model data structure. The interior of the model is filled with triangular prism voxels to ensure the simulation accuracy of the top and bottom plate interfaces and reduce the amount of model data.

[0088] Specifically, step five includes:

[0089] S1, extract a triangle from the Delaunay triangulation network of the ground surface, and set this triangle as the upper triangle of the first generalized triangular prism;

[0090] S2, according to the stratigraphic numbers of the three vertices of the upper triangle, a new triangle is extended downward along the borehole according to the reasoning rules of three-dimensional structural knowledge. The new triangle is called the lower triangle;

[0091] S3, construct a generalized triangular prism according to the correspondence between the upper triangle and the lower triangle in the triangle bidirectional linked list and the drilling point chain, record the description information of the generalized triangular prism, and set the lower triangle to the upper triangle;

[0092] Repeat S2 and S3 until the vertices of the upper triangle are the bottom points of their respective drilling holes;

[0093] Repeat S1 to S4 until all the triangles of the ground surface TIN are traversed.

[0094] The above three-dimensional modeling method for fault-containing geological bodies is suitable for dynamic modification of faults and geological models. When new borehole data is added, it is only necessary to locally modify the Delaunay triangulation network on the surface, and then expand the locally modified triangles downward along the borehole according to the knowledge reasoning rules to generate a new generalized triangular prism.

[0095] Introducing tetrahedral elements into the GTP model can fully express the layered geological body without changing the structure of the original GIP model; secondly, the tetrahedron is a 3D simplex, which is convenient for spatial operations such as plane cutting and volume calculation. This study proposes a method for reorganizing the topological relationship of GTP. This method does not require adding any auxiliary lines and points to GTP, but completely relies on the vertices contained in GTP itself and the intersection of the section plane and GTP. The polyhedron retained after sectioning is reorganized into multiple tetrahedral units, so this method can support multiple sectioning of the GTP model.

[0096] The following are the complete section types of GTP voxels and the corresponding topological relationship-based reorganization methods, taking the retention of the lower half of GTP as an example. Figure 3 As shown in Figure 2. This reorganization of GTP based on the topological relationship of GTP elements is not affected by the morphological characteristics of GTP elements and the degeneration of TIN surfaces. The only constraint is that the side of the GTP element cannot be non-planar. Therefore, this is a reorganization method that can support multiple sections of GTP.

[0097] The present invention proposes a dynamic reconstruction method based on GTP topology relationship, the steps are as follows:

[0098] Determine the plane equation of the section, determine the positional relationship between each GTP voxel vertex and the plane, and delete all GTP voxels whose vertices are located in the non-retained part of the plane from the linked list;

[0099] Traverse the GTP voxels in the Quaternary 3D geological model based on MD-GTP-TEN, perform dynamic tetrahedral partitioning operations on the remaining GTP voxels, and obtain all GTP voxels to be partitioned;

[0100] Determine the sectioning type and the corresponding reorganization method according to the positional relationship between the vertices of the GTP to be sectioned and the sectioning plane;

[0101] Find the intersection of the cutting plane and GTP;

[0102] According to the reorganization method, the GTP volume element to be sectioned is reorganized into a number of tetrahedral GTP volume elements, and the topological relationship of the Quaternary three-dimensional geological model based on MD-GTP-TEN is updated;

[0103] Invalid and redundant data are eliminated, and the sectioning results are rendered and visualized.

[0104] In addition, for the two types of special sectioning and pseudo sectioning, since the probability of their occurrence in actual situations is extremely small and their sectioning and reconstruction methods are similar to those of complete sectioning, they will not be described in detail in this embodiment.

[0105] The real boreholes that were not involved in the construction of the Quaternary 3D geological model based on MD-GTP-TEN were selected for comparative analysis with the virtual boreholes extracted from the corresponding positions in the Quaternary 3D geological model based on MD-GTP-TEN; the real boreholes were taken as the standard, and the differences in stratum burial depth and layer thickness between the virtual boreholes and the real boreholes were analyzed to reflect the accuracy of the Quaternary 3D geological model based on MD-GTP-TEN. Since the real boreholes may not have exposed a certain geological body, and the controlled depth of the Quaternary 3D geological model of a certain city is 364.2m, it is obvious that there is a difference between the virtual borehole depth extracted from the Quaternary 3D geological model and the real borehole depth. Therefore, the last layer of the real borehole and the virtual borehole does not participate in the evaluation of the mathematical accuracy of the model.

[0106] When conducting comparative analysis of the buried depth error of geological roof body between real borehole and virtual borehole at the same location, the error of the buried depth of roof body of a certain layer in the real borehole and the buried depth of roof body corresponding to the virtual borehole is calculated; the buried depth error of roof body of the i-th layer of the borehole is:

[0107] P i =|A vi -A ri |(1)

[0108] Where P i represents the top plate buried depth error of the virtual borehole i-th geological body, A vi represents the top plate depth of the virtual borehole i-th geological body, A ri Represents the top burial depth of the geological body of the i-th layer of the actual borehole;

[0109] The error of the top plate burial depth of the entire borehole is calculated comprehensively as the error of the Quaternary three-dimensional geological model near the borehole; the error of the top plate burial depth of the entire borehole is:

[0110]

[0111] Where P represents the top plate burial depth error of the entire virtual borehole geological body, and n represents the total number of virtual borehole layers involved in the calculation.

[0112] When conducting a comparative analysis of the layer thickness error between the real borehole and the virtual borehole at the same location, the error between the layer thickness of a layer in the real borehole and the layer thickness corresponding to the virtual borehole is calculated; the layer thickness error of the i-th layer of the borehole is:

[0113] Q i =|D vi -D ri | (3)

[0114] In the formula, Q i represents the layer thickness error of the virtual drilling layer i, D virepresents the layer thickness of the virtual drilling layer i, D ri represents the layer thickness of the i-th layer of the actual drilling;

[0115] The layer thickness error of the entire borehole is calculated comprehensively as the error of the three-dimensional geological model near the borehole; the layer thickness error of the entire borehole is:

[0116]

[0117] Where Q represents the layer thickness error of the entire virtual drilling hole, and n represents the total number of virtual drilling layer layers involved in the calculation.

[0118] Quaternary geological boreholes are the basis for the three-dimensional model. The borehole model is modeled using a regular grid, and its basic modeling unit is a standard triangular prism. Each borehole is composed of several vertically adjacent geometric cylinders, and cylinders of different colors represent different strata.

[0119] The Quaternary 3D geological modeling is divided into the shallow Quaternary 3D geological model and the complete Quaternary 3D geological model. The shallow Quaternary 3D geological model mainly reflects the 3D structure of the Quaternary strata below 6m on the surface. The modeled strata are divided according to the sedimentary phase, from top to bottom: cultivated soil layer, beach phase sedimentary strata and coastal phase sedimentary strata. The stratigraphic division results of the shallow Quaternary 3D geological model are shown in Table 1. The complete Quaternary geological 3D model reflects the 3D spatial structure of the Quaternary strata in the urban geological survey area since the Neogene. The modeled strata are divided into groups and segments according to the stratigraphic depositional age. From top to bottom, the stratigraphic division results of the complete Quaternary 3D geological model are shown in Table 2.

[0120] Table 1 List of standardized divisions of strata in the shallow Quaternary three-dimensional geological model

[0121]

[0122]

[0123] Table 2 List of standardized divisions of strata in the complete Quaternary 3D geological model

[0124]

[0125] The shallow Quaternary 3D geological model was generated by using the data of 28 Quaternary trough boreholes in the study area. The complete Quaternary 3D geological model was generated by using the data of 81 Quaternary boreholes in the study area and combining them with the data of the Quaternary geological profile.

[0126] The composite sectioning forms of the Quaternary three-dimensional geological model include arbitrary multiple plane sectioning, tunnel excavation simulation, and space excavation. This study used 81 slot boreholes and 28 Quaternary boreholes, with a grid step of 1.2 km and a longitudinal stretching ratio of 1500 to construct a Quaternary geological three-dimensional model containing a total of 10,504 GTP elements. When performing a single arbitrary section section on the model, the time generally does not exceed 0.5s. Using the geological body top burial depth evaluation model and the layered thickness evaluation model, the error statistics of the Quaternary three-dimensional geological model of a certain city were performed. Table 3 gives the statistical results of the errors in the geological body top burial depth and layered thickness. The frequency statistics of each error interval are as follows. Figure 4 shown.

[0127] Table 3 Statistics of the buried depth and layer thickness errors of the Quaternary three-dimensional geological model of a city

[0128]

[0129] The trimmed mean refers to the average after removing the 5% larger error values; the 10% trimmed mean refers to the average after removing the 10% larger error values.

[0130] Figure 4 (a) shows that the number of boreholes with a geological depth error of less than 5m accounts for 87.94%, and the number of boreholes with an error of less than 10m accounts for 91.84%. The average geological depth error is 3.05m, the standard deviation is 2.46m, and the average after excluding 10% of the larger error values ​​is 1.45m. The error value is 5.95~15.60m. Figure 4 (b) shows that the number of boreholes with layer thickness errors less than 5m accounts for 91.84%, and the number of boreholes with errors less than 10m accounts for 96.10%. The average error of geological body burial depth is 2.42m, the standard deviation is 2.09m, and the average after eliminating 10% of the larger error values ​​is 1.13m. The error value is 4.14~14.97m.

[0131] In summary, the Quaternary 3D geological model of a city constructed based on MD-GTP-TEN in this study fully reflects the existing geological knowledge and conforms to geological laws. The results show that the mean error of geological body burial depth is 3.05m, and the mean error of layer thickness is 2.42m, which proves the high reliability of the Quaternary 3D geological model of a city.

[0132] The above-described embodiments of the present invention do not limit the protection scope of the present invention.

Claims

1. A refined Quaternary three-dimensional geological modeling integrated method, characterized in that: include: Step 1: Obtain basic geological data and drilling data of the study area, wherein the basic geological data includes bedrock geological data and Quaternary geological data; the drilling data is modeled using an irregular triangulated network, and the basic unit of the irregular triangulated network is GTP; Step 2: standardize the drilling data; Step 3: divide the Quaternary stratigraphic units of the study area according to basic geological data; Step 4: DEMs of stratum interfaces are established from the surface to the underground in sequence according to the drilling data, and adjacent DEMs belonging to the same stratum are stitched to form a three-dimensional stratum model based on multi-layer DEMs; Step 5: Divide the GTP into TENs, and construct a Quaternary three-dimensional geological model based on MD-GTP-TEN according to the three-dimensional stratigraphic model based on the multi-layer DEM and using TENs as basic volume elements.

2. A refined Quaternary three-dimensional geological modeling integrated method as claimed in claim 1, characterized in that: Step 2 includes: The spatial data in the drilling data are unified into the CGCS2000 coordinate system; Draw the Quaternary geological profile according to the original borehole stratification information in the drilling data, and make stratification comparison between boreholes in combination with the corresponding lithology description and test results; Based on the stratification comparison results between the boreholes, an initial standard stratification is assigned to each stratum on the Quaternary geological cross section; By comparing multiple sections, the drilling stratification is modified and the standard stratification results are adjusted to obtain a unified standard stratum; Other boreholes are standardized one by one according to the standard formation.

3. A refined Quaternary three-dimensional geological modeling integrated method as claimed in claim 1, characterized in that: Step 4 includes: Determine the boundary range of the modeling area and the stratigraphic number corresponding to each intersection point; Interpolation calculation is performed according to the intersection points. Based on the triangulation generation algorithm, an irregular triangulated network TIN model is constructed to organize the discrete points on each sub-TIN that constitutes the stratum interface or fault, the intersecting arcs of each sub-TIN, and establish the topological relationship between TIN and arcs, and between the stratum interface and each sub-TIN; The Delaunay TIN construction method was used to model each sub-TIN surface, and the shortest diagonal method was used to model the fault sub-surface; Select inverse distance weighting, moving surface fitting and spatial kriging interpolation methods to organize the interpolation points and establish a unified plane grid point; When the stratum interfaces intersect, determine whether each triangular unit of the adjacent stratum interfaces intersects; if there is an intersection, find the intersection line of the two triangular units; delete the redundant triangular unit parts according to the topological relationship, and then reconstruct the remaining polygons.

4. A refined Quaternary three-dimensional geological modeling integrated method as claimed in claim 1, characterized in that: Step five includes: S1, extract a triangle from the Delaunay triangulation network of the ground surface, and set this triangle as the upper triangle of the first generalized triangular prism; S2, according to the stratigraphic numbers of the three vertices of the upper triangle, a new triangle is extended downward along the borehole according to the reasoning rules of three-dimensional structural knowledge. The new triangle is called the lower triangle; S3, construct a generalized triangular prism according to the correspondence between the upper triangle and the lower triangle in the triangle bidirectional linked list and the drilling point chain, record the description information of the generalized triangular prism, and set the lower triangle to the upper triangle; Repeat S2 and S3 until the vertices of the upper triangle are the bottom points of their respective drilling holes; Repeat S1 to S4 until all the triangles of the ground surface TIN are traversed.

5. A refined Quaternary three-dimensional geological modeling integrated method as claimed in claim 1, characterized in that: The method also includes a dynamic reconstruction method based on the GTP topology relationship, the steps are as follows: Determine the plane equation of the section, determine the positional relationship between each GTP voxel vertex and the plane, and delete all GTP voxels whose vertices are located in the non-retained part of the plane from the linked list; Traverse the GTP voxels in the Quaternary 3D geological model based on MD-GTP-TEN, perform dynamic tetrahedral partitioning operations on the remaining GTP voxels, and obtain all GTP voxels to be partitioned; Determine the sectioning type and the corresponding reorganization method according to the positional relationship between the vertices of the GTP to be sectioned and the sectioning plane; Find the intersection of the cutting plane and GTP; According to the reorganization method, the GTP volume element to be sectioned is reorganized into a number of tetrahedral GTP volume elements, and the topological relationship of the Quaternary three-dimensional geological model based on MD-GTP-TEN is updated; Invalid and redundant data are eliminated, and the sectioning results are rendered and visualized.

6. A refined Quaternary 3D geological modeling integrated method as claimed in claim 1, characterized in that: The method further comprises: The real boreholes that were not involved in the construction of the Quaternary 3D geological model based on MD-GTP-TEN were selected for comparative analysis with the virtual boreholes extracted from the corresponding positions in the Quaternary 3D geological model based on MD-GTP-TEN; Taking the real borehole as the standard, the differences between the virtual borehole and the real borehole in terms of stratum burial depth and layer thickness are analyzed to reflect the accuracy of the Quaternary 3D geological model based on MD-GTP-TEN.

7. A refined Quaternary three-dimensional geological modeling integrated method as claimed in claim 6, characterized in that: include: When conducting comparative analysis of the buried depth error of geological roof body between real borehole and virtual borehole at the same location, the error of the buried depth of roof body of a certain layer in the real borehole and the buried depth of roof body corresponding to the virtual borehole is calculated; the buried depth error of roof body of the i-th layer of the borehole is: P i =|A vi -A ri |(1) Where P i represents the top plate buried depth error of the virtual borehole i-th geological body, A vi represents the top plate depth of the virtual borehole i-th geological body, A ri Represents the top burial depth of the geological body of the i-th layer of the actual borehole; The error of the top plate burial depth of the entire borehole is calculated comprehensively as the error of the Quaternary three-dimensional geological model near the borehole; the error of the top plate burial depth of the entire borehole is: Where P represents the top plate burial depth error of the entire virtual borehole geological body, and n represents the total number of virtual borehole layers involved in the calculation.

8. A refined Quaternary three-dimensional geological modeling integrated method as claimed in claim 6, characterized in that: include: When conducting a comparative analysis of the layer thickness error between the real borehole and the virtual borehole at the same location, the error between the layer thickness of a layer in the real borehole and the layer thickness corresponding to the virtual borehole is calculated; the layer thickness error of the i-th layer of the borehole is: Q i =|P vi -D ri | (3) In the formula, Q i represents the layer thickness error of the virtual drilling layer i, D vi represents the layer thickness of the virtual drilling layer i, D ri represents the layer thickness of the i-th layer of the actual drilling; The layer thickness error of the entire borehole is calculated comprehensively as the error of the three-dimensional geological model near the borehole; the layer thickness error of the entire borehole is: Where Q represents the layer thickness error of the entire virtual drilling hole, and n represents the total number of virtual drilling layer layers involved in the calculation.

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