A method and system for automatically dividing quaternary strata in a plain region

Abstract

The application discloses a plain area quaternary stratum automatic division method and system, relates to stratum division, and comprises the following steps: preliminarily dividing strata and calculating the elevation of the boundary line of each major quaternary layer; setting the stratum number of each drill column; according to indoor test data and test data proportion threshold, the initial drill stratum is corrected for the first time; the first corrected drill stratum is cut by using in-situ test data and the thickness threshold of thick sand and gravel stratum; according to the filling stratum lithology merging information, the quaternary stratum and the recent deposition stratum lithology merging information, the interbedding coefficient threshold and whether the interbedding coefficient merging stratum parameter is used, the cut drill stratum is merged; according to the elevation of the boundary line of each major quaternary layer, the stratum number of the drill column in the merged drill stratum is corrected for the second time. The application realizes the automatic stratum division technology of the plain area stratum based on field drilling, indoor test and in-situ test.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of stratum division, in particular to a plain area Quaternary stratum automatic division method and system. BACKGROUND

[0002] Quaternary stratum refers to geological sedimentary layer formed about 258 million years ago, and is an important research object in the fields of engineering construction, resource development and environmental protection. In the plain area, due to the stable geological structure, Quaternary stratum is generally developed, and its distribution characteristics, thickness variation and physical and mechanical properties have important influences on urban construction, underground engineering and groundwater resource evaluation. Accurate division of Quaternary stratum is a basic work of engineering geological investigation, hydrogeological survey and geological disaster assessment.

[0003] At present, the division of Quaternary stratum is influenced by complex and variable lithology, various genetic types, lateral and vertical discontinuity of stratum, and non-consistency of engineering index and stratum interface, etc., which puts forward higher requirements on survey engineers. The traditional division method excessively depends on the subjective experience of survey engineers, lacks quantitative indexes and scientific basis, and leads to differences in the division results of the same area by different technical personnel.

[0004] The prior art application number: CN201310003899.8 discloses a rock and soil engineering investigation graphical layering and data processing method based on standard soil layer, comprising the following steps: 1) in the case of unified analysis of existing data, all the most representative soil layers in a site are extracted, and the properties of each soil layer are defined; 2) the logical relationship between the standard soil layer and the single-hole layering is established, that is, each standard soil layer is used as a template, the in-situ test results of each exploration hole are compared, and the layer positions not appearing in each hole are deleted on the standard soil layer to complete the single-hole layering of the exploration hole; 3) if there is a difference in the selection of the standard soil layer in the template during the review, the data information of the standard soil layer in the template is modified, and the soil layer data information of each exploration hole is automatically modified accordingly; 4) after the rock and soil engineering layering data of each hole are obtained, the data are statistically analyzed; 5) the results of layering and statistical analysis are displayed graphically. However, this method is a general soil layer classification method, and is not designed specifically for the characteristics of Quaternary stratum. SUMMARY

[0005] In view of the low stratum division precision near the main layer boundary in the prior art, the present application provides a plain area Quaternary stratum automatic division method and system, which improves the stratum division precision near the main layer boundary by fusing sedimentary cycle characteristics and stratum division methods.

[0006] The purpose of the present application is achieved by the following technical solutions.

[0007] One aspect of the present application provides a method for automatically dividing Quaternary strata in plain areas, comprising: S1, obtaining field drilling data, laboratory test data and in-situ test data; S2, presetting stratification setting information, which comprises Quaternary stratification thickness array, test data proportion threshold, thick sand and gravel stratum thickness threshold, fill stratum lithology merging information, Quaternary stratum and recent deposition stratum lithology merging information, interbedding coefficient threshold, and whether to merge strata according to interbedding coefficient; S3, preliminarily dividing strata and calculating the elevations of the boundaries of each major Quaternary stratum according to the field drilling data and the Quaternary stratification thickness array; S4, setting the stratum numbers of each drill column according to the preliminarily divided strata to obtain initial drill strata; S5, performing first correction on the initial drill strata according to the laboratory test data and the test data proportion threshold; S6, performing segmentation on the drill strata after the first correction by using the in-situ test data and the thick sand and gravel stratum thickness threshold to obtain segmented drill strata; S7, merging the segmented drill strata according to the fill stratum lithology merging information, the Quaternary stratum and recent deposition stratum lithology merging information, the interbedding coefficient threshold, and whether to merge strata according to interbedding coefficient to obtain merged drill strata; S8, performing second correction on the stratum numbers of the drill columns in the merged drill strata according to the elevations of the boundaries of each major Quaternary stratum to obtain drill strata after the second correction; and S9, merging adjacent drill columns with the same stratum number in the drill strata after the second correction to complete the division of Quaternary strata in plain areas.

[0008] Further, S3, preliminarily dividing strata according to the field drilling data and the Quaternary stratification thickness array, comprises: screening fill stratum drill columns from the field drilling data, grouping the fill stratum drill columns according to lithology, calculating the total length of each lithology drill column, determining the lithology with the longest total length as the main fill stratum layer and numbering it as F1, and numbering the remaining lithologies in order from large to small total length to obtain fill stratum layer numbers.

[0009] Screening recent deposition layer drill columns other than fill stratum from the field drilling data, grouping the recent deposition layer drill columns according to lithology, calculating the total length of each lithology drill column, determining the lithology with the longest total length as the main recent deposition layer and numbering it as N1, and numbering the remaining lithologies in order from large to small total length to obtain recent deposition layer layer numbers; calculating the elevations of the boundaries of each major Quaternary stratum in each drill hole according to the bottom elevations of the fill stratum or recent deposition stratum in the drill hole and the Quaternary stratification thickness array; and numbering the major Quaternary strata as Q1 to Qk in order from top to bottom according to the elevations of the boundaries of the major Quaternary strata.

[0010] For each large layer Qi, search all drill hole columns within the depth range preset at the boundary line of Qi, group the drill hole columns according to lithology, calculate the total length of the drill hole columns of each lithology, and determine the lithology with the longest total length as the main layer of Qi, numbered Qi-1, and the remaining lithologies are sequentially numbered Qi-j in descending order of total length, to obtain the stratigraphic number of each large layer of the Quaternary.

[0011] Further, S5, according to the indoor test data and the test data proportion threshold, a first correction is made to the initial drill hole stratum, including: obtaining all drill hole columns of a drill hole from the initial drill hole stratum; arranging the drill hole columns in ascending order according to the layer bottom depth; obtaining the corresponding test data from the indoor test data according to the sorted layer bottom and layer top elevation; from the obtained indoor test data, determining the lithology with the highest proportion, and correcting the lithology and stratigraphic number of the current drill hole column according to the lithology with the highest proportion; grouping the indoor test data by depth, when the proportion of the second lithology type in any depth range is greater than the test data proportion threshold, the lithology test data is continuously and densely distributed, and the second lithology type is different from the lithology of the current drill hole column, the stratum corresponding to the depth range is determined as a interlayer or a lens at each test data position thereof; inserting the interlayer or lens in the current drill hole column, and determining the corresponding stratigraphic number according to the lithology of the interlayer or lens.

[0012] In engineering geology, a lens refers to a rock layer or a sedimentary body in the form of a convex lens or a flat bean in the stratum, which has the geometric characteristics of thick in the middle and thin at the edges, is often sandwiched between other rock layers, and has a unique engineering geological significance.

[0013] Further, S6, using the in-situ test data and the thick layer sand and gravel stratum thickness threshold, the drill hole stratum after the first correction is segmented to obtain the segmented drill hole stratum, including: searching for sand or gravel stratum drill hole columns with a length exceeding the thick layer sand and gravel stratum thickness threshold; according to the in-situ test data, each thick layer sand or gravel stratum drill hole column is segmented: for a sand layer drill hole column, the density boundary is determined according to the standard penetration data in the in-situ test data; for a gravel layer drill hole column, the density boundary is determined according to the wave velocity data in the in-situ test data; according to the density boundary or the elevation of the boundary line of each large layer of the Quaternary, the drill hole stratum after the first correction is segmented to obtain the segmented drill hole stratum.

[0014] Further, S7, according to the fill stratum lithology merging information, and the Quaternary stratum and the recent deposition stratum lithology merging information, the interbedding coefficient threshold value, and whether to merge the stratum parameters according to the interbedding coefficient, the cut stratum is merged, and the merged stratum is obtained, including: according to the fill stratum lithology merging information, the cut stratum in the fill stratum is merged, and the fill stratum after merging is obtained; the setting value of whether to merge the stratum parameters according to the interbedding coefficient is obtained, and the setting value contains yes and no; when the setting value is yes, according to the Quaternary stratum and the recent deposition stratum lithology merging information, and the interbedding coefficient threshold value, the Quaternary stratum and the recent deposition stratum in the fill stratum after merging are merged; when the setting value is no, according to the Quaternary stratum and the recent deposition stratum lithology merging information, the Quaternary stratum and the recent deposition stratum in the fill stratum after merging are merged.

[0015] Further, when the setting value is yes, according to the Quaternary stratum and the recent deposition stratum lithology merging information, and the interbedding coefficient threshold value, the Quaternary stratum and the recent deposition stratum in the fill stratum after merging are merged, including: according to the Quaternary stratum and the recent deposition stratum lithology merging information, the interbedding coefficient of two strata is calculated pair by pair, when the interbedding coefficient is greater than the interbedding coefficient threshold value, the corresponding two strata are merged, and the preliminary merged stratum is obtained; according to the preliminary merged stratum, the Quaternary stratum and the recent deposition stratum with only a single lithology are screened out, when the proportion of different lithology data in the laboratory test data of the Quaternary stratum and the recent deposition stratum with only a single lithology is greater than the test data proportion threshold value, the auxiliary lithology of the corresponding stratum is added; the auxiliary lithology represents the secondary lithology type existing outside the main lithology type.

[0016] Further, S8, according to the Quaternary each layer boundary elevation, the drill hole stratum number of the drill hole column in the merged stratum is secondly corrected, and the secondly corrected drill hole stratum is obtained, including: traversing each drill hole in the merged stratum, all drill hole columns contained by each drill hole are obtained, and the drill hole columns are arranged in ascending order according to the layer bottom depth, and the drill hole column sequence is obtained; according to the Quaternary each layer boundary elevation, the drill hole column in the drill hole column sequence is secondly corrected.

[0017] Further, according to the fourth layer boundary elevation of each major layer, the borehole column in the borehole column sequence is secondly corrected, including: obtaining the borehole column between the layer top elevation or the layer bottom elevation in all borehole column sequences and passing through the fourth layer boundary elevation of each major layer as the borehole column across the major layer boundary; obtaining the lithology type of the borehole column across the major layer boundary; when the lithology type is fine-grained soil, searching for the corresponding stratum information below the boundary crossed by the borehole column across the major layer boundary, and correcting the corresponding stratum number according to the searched stratum information; when the lithology type is coarse-grained soil, searching for the corresponding stratum information above the boundary crossed by the borehole column across the major layer boundary, and correcting the corresponding stratum number according to the searched stratum information.

[0018] Further, S9, merging the adjacent borehole columns with the same stratum number in the secondly corrected borehole stratum, completing the division of the Quaternary stratum in the plain area, including: obtaining all borehole columns of each borehole in the secondly corrected borehole stratum; arranging the borehole columns in ascending order according to the layer bottom depth; judging whether the stratum numbers of the borehole columns are the same from below to above according to the arranged borehole columns, if the same, marking and deleting the borehole column below; modifying the layer bottom depth of the retained borehole column above, completing the merging of the adjacent borehole columns with the same stratum number in the same borehole.

[0019] Another aspect of the present application also provides a Quaternary stratum automatic division system in a plain area, used for executing the Quaternary stratum automatic division method in the plain area.

[0020] Compared with the prior art, the present application has the following advantages:

[0021] The "sedimentary cycle" in the Quaternary stratum in the plain area is an important geological feature, reflecting the periodic change of the sedimentary environment and the geological evolution process. The present application preliminarily divides the stratum and calculates the fourth layer boundary elevation of each major layer through the field drilling data and the Quaternary layer thickness array, and combines the statistical analysis method with the sedimentology principle. This calculation method considers the integrity of the sedimentary cycle, so as to more accurately identify the real geological boundary, rather than the simple lithology change interface. This provides a basic guarantee for maintaining the integrity of the sedimentary cycle, effectively avoiding the problem that the same sedimentary cycle is incorrectly divided into different major layers. BRIEF DESCRIPTION OF DRAWINGS

[0022] The present application will be further described in the manner of exemplary embodiments, which will be described in detail through the accompanying drawings. These embodiments are not restrictive, and in these embodiments, the same numbers represent the same structures, wherein:

[0023] Figure 1 is an exemplary flow chart of a Quaternary stratum automatic division method in a plain area according to some embodiments of the present application;

[0024] Figure 2 is a technical roadmap of a method for automatic division of Quaternary strata in plain areas according to some embodiments of the present application. DETAILED DESCRIPTION

[0025] The method and system provided by the embodiments of the present application are described in detail below with reference to the drawings.

[0026] As shown in Figure 1 and Figure 2 , field drilling data, laboratory test data and in-situ test data are obtained; preset stratification setting information is obtained, the stratification setting information including a Quaternary stratification thickness array, a test data proportion threshold, a thick sand and gravel stratum thickness threshold, fill stratum lithology merging information, Quaternary stratum and recent deposition stratum lithology merging information, an interbedding coefficient threshold, and whether to merge stratum parameters according to the interbedding coefficient; the strata are preliminarily divided and the elevations of the boundaries of the Quaternary major layers are calculated according to the field drilling data and the Quaternary stratification thickness array; the drill hole stratum number of each drill hole column is set according to the preliminarily divided strata to obtain initial drill hole strata; the initial drill hole strata are corrected for the first time according to the laboratory test data and the test data proportion threshold; the drill hole strata after the first correction are cut according to the in-situ test data and the thick sand and gravel stratum thickness threshold to obtain the cut drill hole strata; the cut drill hole strata are merged according to the fill stratum lithology merging information, the Quaternary stratum and recent deposition stratum lithology merging information, the interbedding coefficient threshold, and whether to merge stratum parameters according to the interbedding coefficient to obtain the merged drill hole strata; the drill hole stratum number of the drill hole column in the merged drill hole strata is corrected for the second time according to the elevations of the boundaries of the Quaternary major layers to obtain the drill hole strata after the second correction; the adjacent drill hole columns with the same drill hole stratum number in the drill hole strata after the second correction are merged to complete the division of the Quaternary strata in the plain area.

[0027] S1, field drilling data, laboratory test data and in-situ test data are obtained. The field drilling data are basic information for strata division, mainly including: drill hole number, coordinate, hole mouth elevation; lithology description information of each drill hole (including color, state, compactness, etc.); layer top depth and layer bottom depth of each soil layer; drill hole profile and core photo; underground water level information. The data are obtained through engineering exploration drilling operation, which requires that the drill hole arrangement should cover the representative positions of the study area and the drill hole depth should reach the complete Quaternary stratum sequence. The continuous coring method should be used during drilling to ensure the integrity of the core and improve the accuracy of the lithology description.

[0028] Laboratory data are the key basis for identifying the physical and mechanical properties of soil layers, mainly including: basic physical property tests of soil samples (water content, density, liquid-plastic limit, etc.); particle analysis tests (particle size distribution, grading curve); mechanical property tests (compression, shear, triaxial, etc.); mineral composition analysis (X-ray diffraction, heavy mineral analysis, etc.). Undisturbed and disturbed soil samples taken from boreholes are sent to the laboratory for systematic physical and mechanical property testing. Sampling locations should include typical soil layers, especially the transition section of the main layer boundary, and special soil layers such as suspected interlayers and lenses. Soil sample testing should be carried out in accordance with relevant engineering geology exploration specifications.

[0029] In-situ test data provide information on the properties of soil layers in their original state, which is particularly important for identifying the internal structure of thick sand and gravel layers. Mainly includes: standard penetration test data (SPT-N value); static cone penetration test data (CPT); dynamic cone penetration test data; wave velocity test data (transverse wave velocity, longitudinal wave velocity); side pressure test data. Various in-situ tests are conducted during drilling or in independent in-situ test holes. Standard penetration tests are usually conducted in cohesive and sandy soils, and wave velocity tests are used to evaluate the density of gravel layers. In-situ test points should be arranged in coordination with drilling points to form a complementary data collection network.

[0030] In particular, the strata in plain areas are relatively complex, and the strata division is difficult, so engineers need to pay attention to many points during geological stratification, which puts high requirements on the survey work. This method innovatively proposes a solution set for the characteristics and professional division requirements and habits of strata in plain areas. It effectively solves the problem of rapid and automatic stratification of strata in plain areas, reduces the workload of engineers, and improves the accuracy and quality of geological stratification. This scheme comprehensively utilizes field drilling data, laboratory test data, and in-situ test data (S1 step) to provide multi-dimensional information for identifying complex sedimentary cycles. In particular, the ability to identify interlayers and lenses using laboratory test data in S5 step, and the method of cutting thick sand and gravel layers using in-situ test data in S6 step, effectively improve the identification and processing ability of atypical or incomplete sedimentary cycles. This multi-source data-driven comprehensive analysis method technically solves the limitations of traditional single data in identifying complex sedimentary cycles.

[0031] S2, presetting stratification setting information, the implementation steps are as follows: reading the automatic stratification setting information from the configuration file and initializing to the interactive interface; editing the automatic stratification setting information in the interactive interface; saving the automatic stratification setting information of the interactive interface to the configuration file. The fourth quaternary stratification thickness array describes the thickness value of each major layer from the fill / newly deposited layer and the quaternary stratification boundary line downward, which is used to preliminarily determine the position of the quaternary stratification boundary line. Specifically, based on regional geological data and existing survey results, the typical sedimentary sequence of the quaternary stratum in the study area is determined; combined with the regional geological development history, the main sedimentary stages are divided, usually including Holocene (Q4), Late Pleistocene (Q3), Middle Pleistocene (Q2), Early Pleistocene (Q1) and the like; the stratigraphic thickness data of the representative drill holes in the region are statistically analyzed to determine the average thickness and variation range of each major layer; the thickness values of each major layer are organized into an array in the order from top to bottom, such as [15, 35, 50, 80], which respectively represent the typical thickness of Q4, Q3, Q2 and Q1.

[0032] The test data proportion threshold value is used to determine the interlayer or lens when the test data of a certain depth range in the drill hole column is different from the current drill hole column lithology, and the proportion of the test data in the total test data of the drill hole column exceeds the threshold value. Specifically, based on statistical principles, a percentage value for distinguishing significant differences is set, usually 15% to 30%; considering the degree of heterogeneity of regional strata, the stronger the heterogeneity, the lower the threshold value should be set; combined with the typical characteristics of interlayers and lenses in the region, the threshold value is optimized; input in percentage form, such as "20%".

[0033] The thick sand and gravel stratum thickness threshold value is used to determine the thick sand and gravel stratum when the length of the sand layer or gravel layer drill hole column exceeds the threshold value, which needs to be further subdivided according to the in-situ test data. Specifically, the typical thickness distribution characteristics of the sand and gravel layer in the study area are analyzed; a reasonable threshold value is determined in combination with engineering geological requirements and in-situ test data distribution; considering the regional sedimentary environment characteristics, such as the alluvial plain area which may need to set a larger threshold value, while the lake plain area can set a smaller threshold value; input the specific value, such as "5.0 meters".

[0034] The fill stratum lithology merging information defines which lithology types in the fill stratum can be merged and processed to simplify the expression of the complex structure of the fill stratum. Specifically, a classification table of common lithology types in the fill stratum is established; the mergable lithology combinations are determined according to the similarity principle of engineering characteristics; set as lithology pairing list, such as "plain fill + miscellaneous fill", "construction waste + household waste", etc.; each combination of merging information contains the source lithology type and the target lithology type.

[0035] In the fourth step, the stratigraphic structure is simplified by merging the strata with similar lithology. The merging information of the Quaternary and Neogene strata is combined, which defines which lithology types in the Quaternary and Neogene strata can be merged for processing. This is used to simplify the stratigraphic structure and maintain the continuity of the geological body. Specifically, the common lithology combinations in the Quaternary and Neogene strata of the study area are analyzed and studied. The merging combinations are determined based on the similarity of the genetic characteristics and the similarity of the physical and mechanical properties. The lithology pairing list is set, such as "silty clay + clay", "fine sand + medium sand", etc. Each merging information contains a priority setting to ensure the orderly progress of the merging process.

[0036] In the fourth step, the stratigraphic structure is simplified by merging the strata with similar lithology. The merging information of the Quaternary and Neogene strata is combined, which defines which lithology types in the Quaternary and Neogene strata can be merged for processing. This is used to simplify the stratigraphic structure and maintain the continuity of the geological body. Specifically, the common lithology combinations in the Quaternary and Neogene strata of the study area are analyzed and studied. The merging combinations are determined based on the similarity of the genetic characteristics and the similarity of the physical and mechanical properties. The lithology pairing list is set, such as "silty clay + clay", "fine sand + medium sand", etc. Each merging information contains a priority setting to ensure the orderly progress of the merging process.

[0037] In the fourth step, the stratigraphic structure is simplified by merging the strata with similar lithology. The merging information of the Quaternary and Neogene strata is combined, which defines which lithology types in the Quaternary and Neogene strata can be merged for processing. This is used to simplify the stratigraphic structure and maintain the continuity of the geological body. Specifically, the common lithology combinations in the Quaternary and Neogene strata of the study area are analyzed and studied. The merging combinations are determined based on the similarity of the genetic characteristics and the similarity of the physical and mechanical properties. The lithology pairing list is set, such as "silty clay + clay", "fine sand + medium sand", etc. Each merging information contains a priority setting to ensure the orderly progress of the merging process.

[0038] In particular, the present scheme sets the stratification setting information in S2 step, including Quaternary stratification thickness array, test data proportion threshold and other parameters, to build a flexible division mechanism that can adapt to the sedimentary cycle characteristics of different regions. This parameterized design enables the system to adjust the division strategy according to the sedimentary law characteristics of the specific region, thereby more accurately identifying and maintaining the local unique sedimentary cycle characteristics, achieving the unity of the universality and regional adaptability of the method.

[0039] S3, preliminarily divide the strata according to the field drilling data and the Quaternary stratification thickness array.

[0040] Firstly, the fill layer is classified and numbered. The fill layer information of all drill holes is extracted from the field drilling database. The drill hole columns marked as "fill" are selected according to the "stratigraphic origin" field in the drilling records. The selected fill layer drill hole columns are grouped according to the lithological characteristics (such as plain fill, miscellaneous fill, construction waste, etc.). The cumulative length of each lithological fill drill hole column is calculated by adding the lengths of all drill hole columns with the same lithology. The lithology with the longest cumulative length is determined as the main layer of the fill layer and numbered as F1. The remaining lithologies are numbered in the order of cumulative length from large to small as F2, F3, F4, etc.

[0041] Next, the newly deposited layer is classified and numbered, and all non-filling layers and drilling columns marked as "newly deposited" are extracted from the drilling database. Check if there are newly deposited layer drilling columns in the screening results, if not, skip this step. If there is a newly deposited layer, group it according to its lithological characteristics. Calculate the cumulative length of each lithological newly deposited layer drilling column. Determine the longest cumulative length of the lithology as the main layer of the newly deposited layer, numbered N1. Determine the longest cumulative length of the lithology as the main layer of the newly deposited layer, numbered N1.

[0042] Finally, the elevations of the boundaries of the major layers of the Quaternary are calculated. For each drilling, the bottom elevation of the filling layer or newly deposited layer is determined as the reference surface for calculation. According to the thickness array of the Quaternary layers and the reference surface elevation, the elevations of the boundaries of the major layers are calculated in turn: the first boundary elevation = the reference surface elevation - the thickness array of the Quaternary layers [0]; the second boundary elevation = the first boundary elevation - the thickness array of the Quaternary layers [1]; and so on, to calculate all the boundary elevations. The results are summarized in the database to form a table of boundary elevations for each drilling.

[0043] The major layers of the Quaternary are numbered and internally layered according to the elevations of the boundaries of the major layers of the Quaternary, in the order from top to bottom, and are numbered Q1 to Qk (k is the number of major layers). For each major layer Qi, the following operations are performed: determine the depth range between the upper and lower boundaries of Qi. Select all drilling columns within this depth range. Group the selected drilling columns according to their lithological characteristics. Calculate the cumulative length of each lithological drilling column. Determine the longest cumulative length of the lithology as the main layer of the major layer, numbered Qi-1. The remaining lithologies are numbered in the order of cumulative length from large to small, numbered Qi-2, Qi-3, etc. The main lithology of different major layers may be the same, but due to different formation periods and sedimentary environments, different numbers should be assigned. For drilling columns that cross the boundary of a major layer, they should be divided according to the position of the boundary to ensure that the drilling columns are correctly attributed to the corresponding major layer. The main layer determination process should consider the engineering geological significance of the lithology, and preferentially select the lithology that has a significant impact on engineering as the main layer.

[0044] S4, the key link of applying the stratigraphic classification framework established in S3 to the actual drilling data, through spatial position matching, each drilling column is associated with the corresponding stratigraphic number to form an initial drilling stratigraphic data set. First, extract all drilling column data for each drilling from the database, including layer bottom depth, lithological description, etc. Arrange the drilling columns of each drilling in ascending order according to the layer bottom depth to ensure the processing order from shallow to deep. Verify the continuity of the drilling column data, detect and handle possible depth overlap or gap problems.

[0045] Then calculate the borehole column layer position elevation. For the first (shallowest) borehole column, the layer top depth is 0, and the layer top elevation is equal to the mouth elevation. For subsequent borehole columns, the layer top depth is equal to the layer bottom depth of the previous borehole column. Convert the depth to absolute elevation according to the borehole mouth elevation: layer top elevation = mouth elevation - layer top depth; layer bottom elevation = mouth elevation - layer bottom depth. Ensure the use of a unified elevation reference system, usually using the national elevation reference.

[0046] Match and assign formation numbers. For each borehole column, calculate its spatial overlap with each formation divided in S3: extract the layer top and bottom elevations of the borehole column to form the elevation interval [E_top, E_bottom]; extract the elevation interval [L_top, L_bottom] of each formation in S3; calculate the overlap length: overlap length = min(E_top, L_top) - max(E_bottom, L_bottom); if the overlap length <= 0, there is no overlap; calculate the overlap ratio: overlap ratio = overlap length / (E_top - E_bottom).

[0047] Select the formation with the largest overlap ratio and assign its number to the current borehole column. When a borehole column spans multiple formations, select the formation with the highest overlap degree, and when the overlap degrees are similar, consider the consistency of lithology for secondary judgment, and when there is no obvious overlap, consider the formation numbers of adjacent borehole columns to maintain formation continuity. For borehole columns that cross large formation boundaries, this step only performs preliminary assignment, and subsequent steps will perform more detailed processing.

[0048] Construct the initial borehole formation data set, record the assigned formation number for each borehole column, and form the initial borehole formation data structure. Check the reasonableness and continuity of the borehole formation numbers, and mark abnormal assignments that may have problems. Save the initial borehole formation data to the database as input for subsequent correction steps. Build a complete data structure containing borehole number, borehole column identification, layer top / bottom depth, layer top / bottom elevation, and formation number.

[0049] S5, use laboratory test data to correct the initial borehole formation formed in S4, especially to identify and add interlayers and lenses that may be ignored in the preliminary division. Through this key basis of laboratory test data, improve the accuracy and reliability of formation division, and make the automatic division results more consistent with the actual geological conditions.

[0050] First, read all the borehole column information for each borehole, including initial formation number, lithology description, layer bottom depth, etc. Arrange the borehole columns in ascending order of layer bottom depth to ensure the processing order from top to bottom. Associate laboratory test data with spatial location of boreholes to establish a mapping relationship of borehole-depth-test data.

[0051] Correct the lithology of the borehole column, and for each borehole column, screen all the laboratory test data within its depth range. Calculate the frequency of occurrence of each lithology type in the test data to determine the dominant lithology: count the number of test samples of each lithology; calculate the proportion of each lithology type in the total test samples; and determine the lithology type with the highest proportion. Compare the consistency of the dominant lithology with the original lithology of the borehole column: if consistent, keep the original stratigraphic number; if not, update the lithology description of the borehole column according to the dominant lithology, and adjust the stratigraphic number accordingly.

[0052] Divide the depth paragraphs and identify interlayers, arrange the screened test data in ascending order of depth. Compare the lithology of adjacent test data one by one from top to bottom, and mark as a potential paragraph boundary when a change occurs. According to the change in lithology and the continuity of depth, divide the test data into multiple paragraphs with relatively consistent lithology. Determine the interlayer for each paragraph: calculate the paragraph thickness (depth difference); compare the paragraph lithology with the original borehole column lithology; when the paragraph thickness is greater than the "test data proportion threshold for determining whether to add a new stratum" and the lithology is different from the original borehole column, it is determined to be an interlayer or lens.

[0053] Insert interlayer borehole columns and assign stratigraphic numbers: for borehole columns determined to contain interlayers, split them into multiple sub-borehole columns according to the location of the interlayer. Create a new borehole column record for each identified interlayer, including the top depth, bottom depth, lithology, etc. Based on the lithology of the interlayer, find a matching stratigraphic number in the existing stratigraphic classification system: first find a stratigraphic number with the same lithology within the current major layer; if not found, check if a new stratigraphic number needs to be created. Assign the found stratigraphic number to the interlayer borehole column. Reorganize the split original borehole column and the newly added interlayer borehole column by depth.

[0054] Update the stratigraphic division information: when the identified interlayer requires a new stratigraphic number, generate a new number according to the rules and update the stratigraphic division information database. Enter the characteristics of the new stratum, including the main physical and mechanical indicators, genetic type, etc. Update the spatial distribution information of the stratum according to the distribution of the interlayer.

[0055] S6 step is mainly aimed at further subdividing the thick sand and gravel layers in the borehole stratum after the correction in S5 step, using in-situ test data to identify the density variation interfaces within these thick layers, and achieving more precise stratigraphic division. This step is of great significance to improve the accuracy of sand and gravel stratigraphic division, especially for sand and gravel strata in plain areas that are significantly affected by sedimentary cycles.

[0056] Screening thick-layer sand and gravel strata, determine screening criteria according to the "thick-layer sand and gravel strata thickness threshold" parameter (usually set to 5-10 meters). Screen the drill columns with lithology of sandy soil (including fine sand, medium sand, coarse sand, etc.) or gravel soil from all drill columns. Calculate the length of each sandy soil or gravel soil drill column (layer bottom depth minus layer top depth). Compare the drill column length with the thickness threshold to determine whether it is a thick-layer sand and gravel stratum.

[0057] Identify and segment sand layer density boundaries. For the identified thick-layer sandy soil drill column, search for all standard penetration test (SPT) data within its depth range. Determine the change in sand density according to the SPT-N value: usually take N values of 10, 15, 30 as the dividing values for loose, slightly dense, medium dense, and dense; when the density grade of adjacent points changes, interpolate between the two points to determine the accurate boundary depth. Segment the original drill column at the determined density boundary position to form multiple sub-drill columns with different densities.

[0058] Identify and segment gravel layer density boundaries. For the identified thick-layer gravel drill column, search for wave velocity test data within its elevation range, including shear wave velocity (Vs) and longitudinal wave velocity (Vp). Correspond the wave velocity point elevation to the drill column elevation range to form an elevation-wave velocity value relationship curve. Determine the gravel layer density grade based on the wave velocity range: usually shear wave velocity 250-300 m / s is slightly dense, 300-400 m / s is medium dense, and 400-500 m / s is dense. Analyze the trend of wave velocity data to determine the point of significant change: when the wave velocity of a point changes across the range, it is determined to be a density change interface; identify the abrupt point through wave velocity gradient analysis. Segment the original drill column at the identified density boundary position to form sub-drill columns with different densities.

[0059] When a specific thick-layer sand and gravel stratum lacks direct in-situ test data, spatial interpolation can be performed using similar depth test data from adjacent drill holes. If spatial interpolation is not feasible, use the "Quaternary layering elevation" calculated in step S3 as the segmentation basis: check whether the thick-layer sand and gravel drill column crosses the Quaternary layer boundary; if it crosses the boundary, segment at the boundary position; the segmented sub-drill columns belong to the corresponding Quaternary layer.

[0060] Update the stratum division information and assign appropriate stratum numbers to each segmented sub-drill column: sub-drill columns with different densities but the same lithology should be assigned different stratum numbers; the numbering rule can use the original number with a density suffix, such as "Q2-3-D" for dense Q2-3 sand layer. Supplement the physical and mechanical property information of the newly divided strata, especially the parameters related to density. Update the spatial distribution information of the strata based on the segmentation results.

[0061] Step S7 intelligently merges the strata subdivided in the previous steps. By merging fill strata and Quaternary / Neogene sedimentary strata, and through an interbedding coefficient evaluation mechanism, it achieves a reasonable simplification and optimization of stratigraphic division. This step solves the balance problem between over-subdivision and maintaining geological continuity, and in particular, ensures the complete representation of sedimentary cycles in stratigraphic division, making it a key step in rationalizing stratigraphic division.

[0062] First, the "fill strata lithology merging information" is read from the configuration file. This information contains a list of fill lithology combinations that need to be merged, such as "clay silt fill, sandy silt fill," "construction waste fill, domestic waste fill," etc. The merging information is then parsed into pairings of source and target lithology types to determine the dominant lithology to be retained after merging. Processing priorities are set for multiple merging rules to avoid conflicts during the merging process.

[0063] Identify and analyze the fill strata, retrieving stratigraphic information for all fill layers from the current stratigraphic classification data. For each fill stratum, statistically analyze its distribution range, overall thickness, and frequency of occurrence throughout the study area. Analyze the spatial relationships of different lithologies within the fill layers, identifying frequently interbedded lithological combinations.

[0064] Merging fill layers involves identifying fill layer pairs that meet the merging criteria according to the merging rules. Appropriate lithological descriptions, numbering, and physical and mechanical properties are determined for the merged strata: lithology is typically retained as the dominant lithology or a composite description is used; numbering prioritizes retaining the numbers of strata with a larger number or wider distribution. All borehole string information involving the merged strata is modified, updating the original strata numbers to the merged numbers. The stratigraphic classification database is updated, deleting the merged strata and updating the properties of the retained strata.

[0065] Merge Quaternary / Neogene sedimentary strata by retrieving the "Merge strata based on interbedding coefficient" parameter from the stratigraphic settings. Select a merging strategy based on the parameter value: "Yes" for "Yes": use the merging path based on interbedding coefficient; "No" for "No": use the direct merging path.

[0066] Based on the merging path of the interbedded stratigraphic coefficient, and according to the "Quaternary / Neogene lithological merging information," the stratigraphic pairs for which the interbedded stratigraphic coefficient needs to be calculated are identified. For each stratigraphic pair, its interbedded stratigraphic coefficient is calculated: the occurrence of the two stratigraphic pairs in all boreholes is statistically analyzed; the frequency of alternation of the two stratigraphic pairs in the same borehole is identified; the interbedded stratigraphic coefficient is calculated as (number of alternations of the two stratigraphic pairs) / (total number of boreholes in which the two stratigraphic pairs coexist). The calculated interbedded stratigraphic coefficient is compared with the "interbedded stratigraphic coefficient threshold" to determine whether the merging conditions are met.

[0067] For the strata pairs with interbedding coefficient greater than the threshold value, determine whether they meet the condition of belonging to the same large stratum. When a stratum meets the merging condition with multiple strata, sort them by interbedding coefficient from high to low to determine the merging order. Perform stratum merging in order: determine the stratum number and dominant lithology after merging; update the stratum information of all related drill columns; update the stratum division database.

[0068] Add secondary lithology. From the merged stratum division information, select strata with only single lithology description. For each single-lithology stratum, analyze the related laboratory test data: count the proportion of different lithologies in the test data; when the proportion of a certain lithology exceeds the "test data proportion threshold for determining whether to add a new stratum" and is different from the current lithology, identify it as a potential secondary lithology. Add the identified significant lithology as the secondary lithology of the stratum: update the stratum description to a composite lithology description; update the lithology information of related drill columns; adjust the physical and mechanical properties of the stratum to reflect the characteristics of the composite lithology.

[0069] Direct merging path. Read the "Quaternary / Neogene stratum lithology merging information" from the configuration file. According to the merging rules, identify the strata pairs that need to be directly merged without considering the interbedding coefficient. Perform stratum merging pair by pair: determine the stratum number and lithology description after merging according to the preset rules; update the stratum information of all related drill columns; update the stratum division database and adjust the stratum attributes.

[0070] Interbedding coefficient reflects the frequency of two strata appearing alternately in space. High interbedding coefficient usually indicates that the two strata may belong to the same sedimentary cycle or different facies in the same sedimentary environment, and are closely related in the geological formation process. Interbedding coefficient = number of interbedding of two strata / total number of drill holes where two strata appear together. When two strata appear alternately in a drill hole (A-B-A or B-A-B pattern), it is counted as one interbedding occurrence. Weight factors can be set according to interbedding thickness, interbedding depth, and regional location: thicker interbedding is given higher weight, different depth ranges can be set with different weights, and spatial weight can be set according to regional geological characteristics.

[0071] Determine the interbedding coefficient threshold value. Determine the initial threshold value based on regional geological experience. By adjusting the threshold value, observe the changes in stratum merging results, and find a reasonable sensitivity balance point. Perform trial merging on typical interbedding regions to evaluate the rationality of the merging results under different threshold values. Set different threshold values according to the characteristics of different regions and different large strata.

[0072] The interbedding phenomenon is usually a direct reflection of energy change in a sedimentary cycle. Different facies strata belonging to the same sedimentary cycle can be identified through interbedding coefficient analysis. Traditional methods may divide different lithological layers in the same sedimentary cycle into independent strata, while the merging mechanism based on the interbedding coefficient of the present application can identify these closely related strata, avoiding artificial segmentation of the sedimentary cycle. The merged strata can better reflect the periodic changes of the sedimentary environment, providing a more reasonable basis for subsequent geological interpretation and engineering application. By maintaining the integrity of the sedimentary cycle, the stratigraphic division result is more in line with the geological formation process, improving the scientificity and rationality of stratigraphic division.

[0073] The S8 step corrects the stratum numbering for the drill hole column across the Quaternary major layer boundary. Through the implementation of a differentiated processing strategy based on the sedimentary cycle rule, it is ensured that the strata in the same sedimentary cycle remain in the same major layer.

[0074] The "Quaternary major layer boundary elevation" data is read from the results calculated in the S3 step. This data contains the boundary elevation values between each major layer at each drill hole location. The integrity and reasonableness of the boundary elevation data are verified, and any abnormal boundary elevation data is identified and marked. Based on the boundary elevation values of each drill hole point, a three-dimensional spatial model of the major layer interfaces in the entire study area is constructed, facilitating subsequent interpolation calculation of the boundary elevation at any location.

[0075] Each drill hole in the study area is traversed, and its basic information (such as hole number, hole opening elevation, etc.) is extracted. For each drill hole, all drill hole columns involved are searched, and information such as layer top depth, layer bottom depth, lithology description, and stratum number is read. All drill hole columns of each drill hole are arranged in ascending order according to the layer bottom depth, ensuring the processing order from shallow to deep. According to the drill hole column depth and the drill hole opening elevation, the layer top elevation and the layer bottom elevation of each drill hole column are calculated: layer top elevation = hole opening elevation - layer top depth; layer bottom elevation = hole opening elevation - layer bottom depth.

[0076] Identify drill hole columns across major layer boundaries. For each drill hole column, check whether its layer top elevation and layer bottom elevation intersect with any major layer boundary elevation: when layer bottom elevation < boundary elevation < layer top elevation, it is determined to cross the boundary; the intersection position of the drill hole column and the boundary is accurately calculated. For the identified cross-boundary drill hole columns, record the boundary information, intersection position, and vertical relationship that they cross. According to the lithology description of the drill hole column, it is determined whether it belongs to fine-grained soil (such as clay, silty clay, etc.) or coarse-grained soil (such as fine sand, medium sand, coarse sand, pebble, etc.).

[0077] For the fine-grained soil borehole column across the boundary of the large layer, search for the corresponding stratum from below the boundary (i.e. deep part): first search for the stratum information of the borehole column immediately below the boundary in the borehole; if there is no suitable stratum in the borehole, search in the same depth range of the spatially adjacent borehole. Replace the original stratum number of the fine-grained soil borehole column across the boundary with the searched lower stratum number, and update the relevant lithology description and stratum attributes. Add a special mark to the corrected borehole column to indicate that it has been processed by the cross-boundary correction. The search for the lower stratum should target the strata within the same sedimentary cycle, and usually prefer coarse-grained soil layers.

[0078] For the fine-grained soil borehole column across the boundary of the large layer, search for the corresponding stratum from below the boundary (i.e. deep part): first search for the stratum information of the borehole column immediately below the boundary in the borehole; if there is no suitable stratum in the borehole, search in the same depth range of the spatially adjacent borehole. Replace the original stratum number of the fine-grained soil borehole column across the boundary with the searched lower stratum number, and update the relevant lithology description and stratum attributes. Add a special mark to the corrected borehole column to indicate that it has been processed by the cross-boundary correction. The search for the lower stratum should target the strata within the same sedimentary cycle, and usually prefer coarse-grained soil layers.

[0079] For the fine-grained soil borehole column across the boundary of the large layer, search for the corresponding stratum from below the boundary (i.e. deep part): first search for the stratum information of the borehole column immediately below the boundary in the borehole; if there is no suitable stratum in the borehole, search in the same depth range of the spatially adjacent borehole. Replace the original stratum number of the fine-grained soil borehole column across the boundary with the searched lower stratum number, and update the relevant lithology description and stratum attributes. Add a special mark to the corrected borehole column to indicate that it has been processed by the cross-boundary correction. The search for the lower stratum should target the strata within the same sedimentary cycle, and usually prefer coarse-grained soil layers.

[0080] S8 step directly solves the key technical problem of maintaining the integrity of the sedimentary cycle in automatic stratification technology by implementing a differentiated processing strategy based on the rules of sedimentary cycles. The present application ensures that the strata in the same sedimentary cycle are attributed to the same large layer, avoiding the problem that a sedimentary cycle may be artificially divided into different large layers by traditional methods. By maintaining the integrity of the sedimentary cycle, a more reliable basis is provided for subsequent sedimentary environment interpretation. The present application not only corrects the stratum number of the borehole column across the boundary of the large layer, but more importantly ensures that the strata in the same sedimentary cycle are attributed to the same large layer, fundamentally improving the geological rationality and engineering application value of stratigraphic division.

Claims

1. A method for automatically dividing a Quaternary stratum in a plain region, characterized by, The method comprises the following steps: S1, acquiring field drilling data, laboratory test data and in-situ test data; S2, presetting stratification setting information, wherein the stratification setting information comprises Quaternary stratification thickness array, test data proportion threshold, thick sand and gravel stratum thickness threshold, fill stratum lithology merging information, Quaternary stratum and recent deposition stratum lithology merging information, interbedding coefficient threshold, and whether to merge stratum parameters according to interbedding coefficient; S3, preliminarily dividing strata and calculating Quaternary stratum boundary elevations according to field drilling data and Quaternary stratification thickness array; S4, setting the stratum numbers of each drill column according to the preliminarily divided strata to obtain initial drill strata; S5, performing first correction on the initial drill strata according to laboratory test data and test data proportion threshold; wherein, based on statistical principles, a percentage value for distinguishing differences is set as the test data proportion threshold, when the test data of a certain depth range in a drill column is different from the current drill column lithology, and the proportion of this part of test data to the total test data of the corresponding drill column exceeds the corresponding threshold, the corresponding depth range is determined as a interlayer or lens; S6, using in-situ test data and thick sand and gravel stratum thickness threshold to cut the drill strata after the first correction to obtain the cut drill strata; S7, merging the cut drill strata according to fill stratum lithology merging information, Quaternary stratum and recent deposition stratum lithology merging information, interbedding coefficient threshold, and whether to merge stratum parameters according to interbedding coefficient to obtain the merged drill strata; S8, performing second correction on the drill stratum numbers of the drill columns in the merged drill strata according to the Quaternary stratum boundary elevations to obtain the drill strata after the second correction; S9, merging the adjacent drill columns with the same stratum number in the drill strata after the second correction to complete the division of Quaternary strata in plain areas.

2. The automatic division method of Quaternary strata in plain areas according to claim 1, wherein: S3, preliminarily dividing strata according to field drilling data and Quaternary stratification thickness array, comprises: selecting fill stratum drill columns from field drilling data, grouping the fill stratum drill columns according to lithology, calculating the total length of each lithology drill column, determining the longest lithology as the main layer of the fill stratum, and numbering it as F1, and numbering the remaining lithologies in descending order of total length to obtain fill stratum stratum numbers; selecting recent deposition layer drill columns except the fill stratum from field drilling data, grouping the recent deposition layer drill columns according to lithology, calculating the total length of each lithology drill column, determining the longest lithology as the main layer of the recent deposition layer, and numbering it as N1, and numbering the remaining lithologies in descending order of total length to obtain recent deposition layer stratum numbers; calculating the Quaternary stratum boundary elevations of each drill according to the bottom elevations of the fill stratum or recent deposition layer in the drill and the Quaternary stratification thickness array; numbering the Quaternary strata in descending order according to the Quaternary stratum boundary elevations as Q1 to Qk. For each large layer Qi, search all drill hole columns within the depth range preset at the boundary line of Qi, group the drill hole columns according to lithology, calculate the total length of drill hole columns of each lithology, and determine the lithology with the longest total length as the main layer of Qi, numbered as Qi-1, and the remaining lithologies are numbered in order of total length from large to small, Qi-j, to obtain the stratigraphic number of each large layer of Quaternary.

3. The automatic division method of Quaternary strata in plain areas according to claim 1, characterized in that: S5, according to the indoor test data and the test data proportion threshold, the initial drill hole stratum is corrected for the first time, including: All drill hole columns of a drill hole are obtained from the initial drill hole stratum; The layer bottom depth of the drill hole column is arranged in ascending order; According to the sorted layer bottom and layer top elevation, the corresponding test data is obtained from the indoor test data; From the obtained indoor test data, the lithology with the highest proportion is determined, and the lithology and stratigraphic number of the current drill hole column are corrected according to the lithology with the highest proportion; According to the depth, the indoor test data is grouped, when the proportion of the second lithology type in any depth range is greater than the test data proportion threshold, and the second lithology type is different from the current drill hole column lithology, the stratum corresponding to the depth range is determined as a interlayer or the corresponding test data position is adjusted as a lens; The interlayer or lens is inserted into the current drill hole column, and the corresponding stratigraphic number is determined according to the lithology of the interlayer or lens.

4. The automatic division method of Quaternary strata in plain areas according to claim 1, characterized in that: S6, using in-situ test data and thick sand and gravel stratum thickness threshold, the drill hole stratum after the first correction is cut, to obtain the cut drill hole stratum, including: Search for sand or gravel stratum drill hole columns with a length greater than the thick sand and gravel stratum thickness threshold; According to the in-situ test data, each thick sand or gravel stratum drill hole column is cut: For sand layer drill hole columns, the density boundary is determined according to the standard penetration data in the in-situ test data; For pebble layer drill hole columns, the density boundary is determined according to the wave velocity data in the in-situ test data; According to the density boundary or the elevation of the boundary line of each large layer of Quaternary, the drill hole stratum after the first correction is cut to obtain the cut drill hole stratum.

5. The automatic division method of Quaternary strata in plain areas according to claim 1, characterized in that: S7, according to the fill stratum lithology merging information, the Quaternary stratum and the recent deposition stratum lithology merging information, the interbedding coefficient threshold, and whether to merge strata according to the interbedding coefficient parameter, the cut drill hole stratum is merged to obtain the merged drill hole stratum, including: According to the fill stratum lithology merging information, the fill stratum in the cut drill hole stratum is merged to obtain the fill stratum merged drill hole stratum; The setting value of whether to merge strata according to the interbedding coefficient parameter is obtained, which contains yes and no; When the setting value is yes, according to the Quaternary stratum and the recent deposition stratum lithology merging information, and the interbedding coefficient threshold, the Quaternary stratum and the recent deposition stratum in the fill stratum merged drill hole stratum are merged. When the setting value is no, the Quaternary and Neogene strata in the borehole strata after merging of the fill layer are merged according to the Quaternary and Neogene strata lithology merging information.

6. The automatic division method of Quaternary strata in plain areas according to claim 5, characterized in that: When the setting value is yes, the Quaternary and Neogene strata in the borehole strata after merging of the fill layer are merged according to the Quaternary and Neogene strata lithology merging information and the interbedding coefficient threshold, comprising: According to the Quaternary and Neogene strata lithology merging information, the interbedding coefficient of each pair of strata is calculated, and when the interbedding coefficient is greater than the interbedding coefficient threshold, the corresponding two strata are merged to obtain the strata after preliminary merging; According to the strata after preliminary merging, the Quaternary and Neogene strata with only a single lithology are screened out, and when the proportion of different lithology data in the laboratory test data of the Quaternary and Neogene strata with only a single lithology is greater than the test data proportion threshold, a secondary lithology of the corresponding stratum is added; the secondary lithology represents the existence of a secondary lithology type in addition to the main lithology type.

7. The automatic division method of Quaternary strata in plain areas according to claim 1, characterized in that: S8, according to the Quaternary major layer boundary elevation, the borehole strata number of the borehole column in the merged borehole strata is secondarily corrected to obtain the borehole strata after second correction, comprising: Each borehole in the merged borehole strata is traversed to obtain all borehole columns contained in each borehole, and the borehole columns are arranged in ascending order according to the layer bottom depth to obtain a borehole column sequence; According to the Quaternary major layer boundary elevation, the borehole columns in the borehole column sequence are secondarily corrected.

8. The automatic division method of Quaternary strata in plain areas according to claim 7, characterized in that: According to the Quaternary major layer boundary elevation, the borehole columns in the borehole column sequence are secondarily corrected, comprising: The borehole columns that pass through the Quaternary major layer boundary elevation between the layer top elevation or the layer bottom elevation in all borehole column sequences are obtained as the cross-major-layer-boundary borehole columns; The lithology type of the cross-major-layer-boundary borehole column is obtained; When the lithology type is fine-grained soil, the corresponding stratum information below the boundary line crossed by the cross-major-layer-boundary borehole column is searched, and the corresponding stratum number is corrected according to the searched stratum information; When the lithology type is coarse-grained soil, the corresponding stratum information above the boundary line crossed by the cross-major-layer-boundary borehole column is searched, and the corresponding stratum number is corrected according to the searched stratum information.

9. The automatic division method of Quaternary strata in plain areas according to claim 1, characterized in that: S9, the adjacent borehole columns with the same borehole strata number in the borehole strata after second correction are merged to complete the division of the Quaternary strata in plain areas, comprising: All borehole columns of each borehole in the borehole strata after second correction are obtained; The borehole columns are arranged in ascending order according to the layer bottom depth; According to the arranged borehole columns, the borehole strata numbers of the borehole columns are judged pair by pair from bottom to top, and if the borehole strata numbers are the same, the borehole column below is marked and deleted; The depth of the layer bottom of the modified reserved upper borehole column is modified, and the merging of the adjacent borehole columns with the same stratum number in the same borehole is completed.

10. A system for automatic division of Quaternary strata in plain areas based on the method of any one of claims 1 to 9.

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