A method for determining shear wave velocity based on a multi-index interval matching decision scheme

Abstract

The present invention discloses a method for determining shear wave velocity based on a multi-index interval matching decision scheme, including: S1, constructing a soil property index and shear wave velocity correlation data set; S2, constructing a soil property index and shear wave velocity interval matching data set; S3, constructing a multi-index interval matching decision scheme; S4, calculating the shear wave velocity according to the soil property index and the decision scheme. The method comprehensively considers the correlation between multiple soil property indexes and shear wave velocity, constructs a multi-index interval matching decision scheme, and compared with the empirical value table in the industry specification, the shear wave velocity value interval is narrowed, which is more convenient for query and use, realizes the shear wave velocity calculation based on the matching interval, avoids the randomness of relying on artificial experience to take values, is more conducive to the reasonable development of engineering design, and can be widely used in the determination of site soil shear wave velocity in the field of engineering survey.

Description

Technical Field

[0001] The invention belongs to the field of engineering geological survey, and in particular relates to a shear wave velocity determination method based on a multi-index interval matching decision scheme. Background Art

[0002] Shear wave velocity is an important engineering characteristic parameter of soil. It can be used to classify building sites, calculate the dominant period of the site foundation, determine foundation liquefaction, and assist in site seismic subdivision and earthquake response spectrum analysis. Shear wave velocity can be obtained by field measurement, but due to the high test cost and site condition restrictions, shear wave velocity tests are currently only carried out on representative sites of important engineering projects. The shear wave velocity of general project sites needs to be determined according to specifications and engineering experience. The specification usually specifies the range of shear wave velocity in the form of a table. For example, the "Railway Engineering Seismic Design Code" stipulates that the shear wave velocity range of fine sand is 100-200m / s, and the shear wave velocity range of medium and coarse sand is 110-250m / s. Since the range of shear wave velocity values ​​given by the specification is usually large, the actual selection of shear wave velocity values ​​is heavily dependent on personal engineering experience, without quantitative use of other soil property indicators, and has a large randomness. It is difficult to accurately determine the shear wave velocity value, which is not conducive to more reasonable engineering project design. Summary of the invention

[0003] In view of the fact that the shear wave velocity value intervals of various soil layers in the current specifications are relatively large, and when there is no measured data on the shear wave velocity of the soil layer, the determination of the shear wave velocity relies on manual experience, has a large randomness, and is not conducive to a more reasonable engineering project design, the present invention provides a method for more finely determining the shear wave velocity of soil by utilizing existing soil property indicators and measured shear wave velocity data and constructing a multi-indicator interval matching decision-making scheme.

[0004] To this end, the technical solution of the present invention is as follows:

[0005] A method for determining shear wave velocity based on a multi-index interval matching decision scheme comprises the following steps:

[0006] S1, construct a data set related to soil properties and shear wave velocity:

[0007] S11, establishing a plane rectangular coordinate system with the ground as the plane to obtain original data;

[0008] S12, calculate the spatial distance l between the soil property index test point and the corresponding test layer center point k :

[0009]

[0010] Where: (X i , Y i) is the plane coordinate of the shear wave test hole; To test the layer top elevation; is the bottom elevation of the test layer; h k is the elevation of the soil property index test point; t is the layer top; b is the layer bottom; i is the number of the shear wave test hole, i = 1, 2, ..., m, m is the number of shear wave test holes; j is the test layer number in the shear wave test hole, j = 1, 2, ..., n i , n i is the number of test layers in the i-th test hole; (X k , Y k ) is the plane coordinate of the soil property index test point, k is the soil property index test point number;

[0011] S13, calculate the soil property index p of the test layer l,i,j :

[0012] When l k = 0, p l,i,j =p l,k ;

[0013] Where: p l,k It is an indicator of soil properties; is the number of soil property index test points within the jth test layer in the i-th shear wave test hole; l = 1, 2, ..., n p , l is the number of soil property index, n p is the number of soil property indicators;

[0014] S14, establish the associated data set S:

[0015]

[0016] Where: d i,j is the depth of the center point of the test layer; v i,j is the shear wave velocity of the test layer;

[0017] S2, build interval matching data set:

[0018] Map the discrete data in the associated data set S in S14 to discrete intervals to obtain an interval matching data set

[0019]

[0020] in is the discrete interval of soil property index; is the depth discrete interval of the center point of the test layer; is the discrete interval of shear wave velocity in the test layer;

[0021] S3, construct a multi-index interval matching decision-making scheme, including the following steps:

[0022] S31, setting a threshold value for the accuracy of interval matching decision;

[0023] S32, calculating the information gain rate of soil property index and test layer center point depth; including the following sub-steps:

[0024] S321, Calculate information entropy

[0025]

[0026] Where: n is the total number of samples contained in the associated data set S, n s is the number of discrete intervals of shear wave velocity in the test layer, n v,w is the number of times the w-th test layer shear wave velocity discrete interval appears in the total number of the test layer shear wave velocity discrete intervals;

[0027] S322, dividing different discrete intervals of soil property indicators and discrete intervals of test point depths into different sub-data sets; calculating the interval matching data set The partition entropy of the lth soil property index in Where: n l is the number of discrete intervals of the lth indicator; is the rth sub-dataset of the lth soil property index; n l,r for The number of samples contained in is the information entropy of the rth sub-data set;

[0028] Calculate the partition entropy of the test point depth n d is the number of discrete intervals of the test point depth, n d,q To divide into the qth sub-dataset The number of samples, is the information entropy of the qth sub-dataset;

[0029] S323, calculate the information gain rate G of soil property index l , as shown below:

[0030]

[0031] S324, calculate the information gain rate G of the test point depth d , as shown below:

[0032]

[0033] S33, using the information gain rate obtained in S32 to select a decision node, and obtain an initial decision plan and the number of samples that meet the decision plan;

[0034] S34, comparing the ratio of the number of samples that meet the decision solution described in S33 to the total number of samples n with the threshold value set in S31, when the ratio is smaller, returning to step S2, recalculating the interval matching data set; when the ratio is larger, obtaining the final decision solution;

[0035] S4, calculate the shear wave velocity:

[0036] The final decision plan obtained by S3 is used to match the soil property index of the target area and the depth of the target test point, and the shear wave velocity of the target test point is calculated.

[0037] The soil property indicators in S1 include at least two of mass density, water content, porosity, plasticity index and standard penetration number.

[0038] The threshold in S31 is ≥ 90%.

[0039] The specific steps of S33 are: select the one with the largest information gain rate among the multiple soil property indicators or test point depths obtained in S32 as the root decision node, and divide the branch subsets according to different discrete intervals in the root decision node; repeat the calculation of the information gain rate on the branch subsets and divide the sub-decision nodes until the leaf node matching is completed, and obtain the decision plan and the number of samples that meet the decision plan.

[0040] In S34, the interval matching data set is recalculated by resetting the length of the discrete interval, the total number of the discrete intervals, or reducing the number of the soil property indicators.

[0041] S4 includes the following steps:

[0042] Obtain soil property indicators of the target area and the target test point depth According to the final decision plan obtained in step S3, the target discrete interval of the soil property index and the target test point depth is determined, and the target discrete interval is and [v min ,v max ];

[0043] Calculate the shear wave velocity v0 of the target area:

[0044]

[0045] Where n xis the number of target discrete intervals, min represents the lower limit of the discrete interval, and max represents the upper limit of the discrete interval; α l , α d are the calculation correction coefficients of soil property index and test point depth, α l =G l / G s , α d =G d / G s ,

[0046] The target discrete interval includes the target soil property index discrete interval, the target test layer center point depth discrete interval and the target test layer shear wave velocity discrete interval; wherein:

[0047] The target soil property index discrete interval is the discrete interval into which the soil property index of the target area falls in the final decision-making scheme;

[0048] The discrete interval of the depth of the center point of the test layer is the discrete interval within which the depth of the target test point falls in the final decision solution;

[0049] The target test layer shear wave velocity discrete interval is the shear wave velocity discrete interval corresponding to the target soil property index discrete interval and the test layer center point depth discrete interval in the final decision plan.

[0050] The present invention has the following advantages and positive effects:

[0051] 1. This method uses spatial interpolation to establish a data set of soil property indicators and shear wave velocity correlation, which can fully reflect the regional characteristics and distribution of each indicator, thereby enhancing the representativeness and diversity of the data set;

[0052] 2. This method comprehensively considers the correlation between multiple indicators and shear wave velocity, and by constructing a multi-indicator interval matching decision-making scheme, it significantly narrows the range of shear wave velocity values, making it easier to query and use;

[0053] 3. This method realizes the quantitative calculation of shear wave velocity based on the multi-index matching interval decision scheme, avoids the randomness of relying on manual experience, and can provide more scientific and reasonable shear wave velocity design parameters for engineering;

[0054] 4. This method can be used to establish a multi-index interval matching decision-making scheme for shear wave velocity in various regions, provide a basis for local shear wave velocity value standards, and avoid the defect of a large range of shear wave velocity values ​​in the current specifications.

[0055] This method can be widely used in determining the shear wave velocity of site soil in the field of engineering investigation. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 is a flow chart of the present invention;

[0057] Figure 2 It is a schematic diagram of the soil property index test points and the shear wave velocity test points in the present invention;

[0058] Figure 3 It is a schematic diagram of a multi-index interval matching decision solution in an embodiment;

[0059] In the figure:

[0060] 1. Shear wave velocity test point; 2. Adjacent area of ​​shear wave velocity test point; 3. Soil property index test point; 4. Ground; 5. Shear wave test hole. DETAILED DESCRIPTION

[0061] The method of the present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0062] See also Figure 1 and Figure 2 The shear wave velocity determination method based on the multi-index interval matching decision scheme of the present invention comprises the following steps:

[0063] S1, construct a data set related to soil properties and shear wave velocity:

[0064] S11, establish a plane rectangular coordinate system with the ground as the plane, and obtain the original data of the existing shear wave velocity test information in the analysis area; including the plane coordinates (X i , Y i ), test layer top elevation Test layer bottom elevation Depth d of the center point of the test layer i,j , shear wave velocity v of the test layer i,j , where: t represents the top of the layer; b represents the bottom of the layer; i = 1, 2, ..., m, i is the number of the shear wave test hole, m is the number of the shear wave test holes; j = 1, 2, ..., n i , j is the test layer number in the shear wave test hole, n i is the number of shear wave test layers in the i-th test hole.

[0065] For the jth shear wave test layer in the i-th shear wave test hole, obtain the soil property index test information in the vicinity of each shear wave velocity test point, including the plane coordinates (X k , Y k ), soil property index test point elevation h k , soil properties index p l,k ,in: k is the soil property index test point number, is the number of soil property index test points within the jth test layer in the i-th shear wave test hole, l = 1, 2, ..., n p , l is the number of soil property index, n p is the number of soil property indicators, which include at least two of mass density, water content, void ratio, plasticity index and standard penetration number;

[0066] S12, calculate the spatial distance l between each soil property index test point and the corresponding shear wave test layer center point k :

[0067]

[0068] S13, calculate the soil property index p corresponding to the shear wave test layer l,i,j :

[0069] When l k = 0, p l,i,j =p l,k ;

[0070] S14, establish a related data set These include the soil property indicators of all test layers in all shear wave test holes calculated in S13, the depth of the center point of the test layer, and the shear wave velocity of the test layer.

[0071] S2, construct the interval matching data set of soil property index and shear wave velocity:

[0072] Set the discrete intervals of various soil property indicators, the discrete intervals of the test layer center point depth, and the discrete intervals of the test layer shear wave velocity, respectively, and perform discrete mapping on the associated data set in step S14 according to the range of the discrete intervals to obtain the interval matching data set

[0073] S3, construct a multi-index interval matching decision-making scheme, including the following steps:

[0074] S31, setting a threshold of the accuracy of interval matching decision, the threshold of the accuracy is not less than 90%;

[0075] S32, matching the data set according to the interval in step S2 Calculate the information gain rate of soil property index and test layer center point depth; including the following steps:

[0076] S321, calculate interval matching data set Information entropy Where: n is the total number of samples contained in the associated data set S, n s is the number of discrete intervals of shear wave velocity, nv,w is the number of times the w-th shear wave velocity discrete interval appears in the total number of shear wave velocity discrete intervals;

[0077] S322, dividing different discrete intervals of soil property indicators and discrete intervals of test point depths into different sub-data sets to calculate interval matching data sets The partition entropy of the lth soil property index in Where: n l is the number of discrete intervals of the lth indicator; is the rth sub-dataset of the lth soil property index; n l,r for The number of samples contained in is the information entropy of the sub-dataset;

[0078] Calculate the partition entropy of the test point depth n d is the number of discrete intervals of the test point depth, n d,q To divide into the qth sub-dataset The number of samples, is the information entropy of the sub-dataset;

[0079] S323, calculating the information gain rate of each soil property index, the information gain rate of the lth index is:

[0080]

[0081] S324, calculate the information gain rate of the test point depth

[0082] S33, selecting the one with the largest information gain rate among multiple soil property indicators or test point depths as the root decision node, and dividing the branch subsets according to different discrete intervals in the root decision node; repeatedly calculating the information gain rates of the remaining soil property indicators or test point depths for the branch subsets and dividing the sub-decision nodes until the leaf node matching is completed, and obtaining the decision plan and the number of samples that meet the decision plan;

[0083] S34, comparing the ratio of the number of samples that meet the decision solution in S33 to the total number of samples n with the threshold set in S31;

[0084] When the ratio is lower than the threshold value set in S31, return to step S2 to reset the discrete interval or reduce the soil property index;

[0085] When the ratio is higher than the threshold value set in S31, a shear wave velocity interval matching decision scheme is obtained;

[0086] S4, calculating the shear wave velocity according to the soil property index and the decision plan, including the following sub-steps:

[0087] Obtain soil property indicators for the target area where the shear wave velocity is to be determined and test point depth According to the shear wave velocity interval matching decision scheme constructed in step S3, the interval scheme corresponding to the soil is determined and [v min ,v max ], where: n x is the number of interval matches, min represents the lower limit of the discrete interval, and max represents the upper limit of the discrete interval; calculate the shear wave velocity v0 of the target area:

[0088]

[0089] In the formula, α l , α d are the calculation correction coefficients of soil property index and test point depth, α l =G l / G s , α d =G d / G s ,

[0090] Example

[0091] The soil property index information and shear wave velocity information of a project area are obtained. Taking some data as examples, the porosity, water content, plasticity index, test depth and shear wave velocity are selected to construct a data set of soil property index and shear wave velocity association, as shown in Table 1.

[0092] Table 1. Datasets of soil properties and shear wave velocity correlation

[0093]

[0094]

[0095] Considering the data distribution of the data set comprehensively, the depth discrete intervals are set to 0-5m, 5-10m, 10-15m, and 15-20m, the porosity discrete intervals are set to 0.5-0.6, 0.6-0.7, and 0.7-0.8, the water content discrete intervals are set to 18-20, 20-22, 22-24, and 24-26, and the plasticity index discrete intervals are set to 8-9, 9-10, 10-11, and 11-12. According to the discrete intervals, the soil property index and shear wave velocity associated data set in Table 1 are discretely mapped to obtain the soil property index and shear wave velocity interval matching data set, as shown in Table 2.

[0096] Table 2 Soil property index and shear wave velocity interval matching data set

[0097]

[0098]

[0099] A multi-index interval matching decision scheme is constructed based on the interval matching data set, and the interval matching decision accuracy threshold is set to 95%. First, the information entropy of the data set is calculated. The data set has 34 samples and the shear wave velocity has 9 value intervals. The information entropy is:

[0100]

[0101] There are 4 value intervals for the test depth, and the entropy is divided into:

[0102]

[0103] The information gain rate of the test depth is:

[0104]

[0105] Similarly, the partition entropy and information gain rate of the soil property indicators porosity, water content, and plasticity index are calculated as follows:

[0106]

[0107]

[0108]

[0109]

[0110]

[0111]

[0112] By comparison, we know that the information gain rate of the test depth is the largest, so the test depth is used as the current division node, and the branch subsets are divided according to the node values; the information gain rate calculation and node selection of the remaining indicators are repeated for the branch subsets until the interval matching is completed, such as Figure 3 As shown, the final accuracy is 97%, which is higher than the set threshold, and the matching decision plan construction is completed.

[0113] The shear wave velocity can be calculated according to the soil property index and the matching decision scheme. Assuming that the soil property index is depth d = 7m, porosity e = 0.563, water content w = 21.2, and plasticity index I = 10.3, the corresponding interval scheme can be determined according to the interval matching decision scheme as depth [5,10], porosity [0.5-0.6], plasticity index [10-11], and shear wave velocity [240-260]. The shear wave velocity is calculated according to the soil property index and the interval scheme as follows:

[0114]

[0115] It can be seen from the examples that by implementing the shear wave velocity determination method based on the multi-index interval matching decision-making scheme of the present invention, the correlation between multiple soil property indicators and shear wave velocity can be comprehensively considered to construct a multi-index interval matching decision-making scheme. Compared with the standard experience value table, the shear wave velocity value interval is narrowed, the quantitative determination of the shear wave velocity is achieved, the randomness of relying on artificial experience is avoided, and it is more conducive to the reasonable implementation of engineering design.

Claims

1. A method for determining shear wave velocity based on a multi-index interval matching decision scheme, characterized in that: The following steps are involved: S1, construct a data set related to soil properties and shear wave velocity: S11, establishing a plane rectangular coordinate system with the ground as the plane to obtain original data; S12, calculate the spatial distance between the soil property index test point and the corresponding test layer center point : ； in:( , ) is the plane coordinate of the shear wave test hole; To test the layer top elevation; To test the bottom elevation of the layer; is the elevation of the soil property index test point; Indicates the top of the layer; Indicates the bottom of the layer; is the number of the shear wave test hole, , is the number of shear wave test holes; is the test layer number in the shear wave test hole, , For the The number of test layers in a test hole; , ) is the plane coordinate of the soil property index test point, Number the test points for soil property indicators; S13, calculate the soil properties index of the test layer : ,when hour, ; in: It is an indicator of soil properties; , For the The first The number of soil property index test points within the test layer; , is the number of the soil property index, is the number of soil property indicators; S14, establish a related data set : , in: is the depth of the center point of the test layer; is the shear wave velocity of the test layer; S2, build interval matching data set: The linked datasets described in S14 The discrete data in is mapped to the discrete interval to obtain the interval matching data set : ， in is the discrete interval of soil property index; is the depth discrete interval of the center point of the test layer; is the discrete interval of shear wave velocity in the test layer; S3, construct a multi-index interval matching decision-making scheme, including the following steps: S31, setting a threshold value for the accuracy of interval matching decision; S32, calculating the information gain rate of soil property index and test layer center point depth; including the following sub-steps: S321, Calculate information entropy : ， in: For the associated dataset The total number of samples included, is the number of discrete intervals of shear wave velocity in the test layer, For the The number of times a shear wave velocity discrete interval of a test layer appears in the total number of shear wave velocity discrete intervals of the test layer; S322, dividing different discrete intervals of soil property indicators and discrete intervals of test point depths into different sub-data sets; calculating the interval matching data set Middle Partition entropy of soil property index ,in: For the The number of discrete intervals of an indicator; For the The first soil property index sub-datasets; for The number of samples contained in For the The information entropy of each sub-dataset; Calculate the partition entropy of the test point depth , is the number of discrete intervals of the test point depth, To divide into Sub-datasets The number of samples, For the The information entropy of each sub-dataset; S323, calculate the information gain rate of soil property indicators , as shown below: ； S324, calculate the information gain rate of the test point depth , as shown below: ； S33, using the information gain rate obtained in S32 to select a decision node, and obtain an initial decision plan and the number of samples that meet the decision plan; S34, the number of samples that meet the decision-making scheme described in S33 accounts for the total number of samples The ratio is compared with the threshold value set in S31. When the ratio is small, return to step S2 to recalculate the interval matching data set; when the ratio is large, obtain the final decision solution; S4, calculate the shear wave velocity: The final decision plan obtained by S3 is used to match the soil property index of the target area and the depth of the target test point, and the shear wave velocity of the target test point is calculated.

2. The shear wave velocity determination method based on the multi-index interval matching decision scheme according to claim 1 is characterized in that: The soil property indicators in S1 include at least two of mass density, water content, porosity, plasticity index and standard penetration number.

3. The shear wave velocity determination method based on the multi-index interval matching decision scheme according to claim 1 is characterized in that: The threshold value described in S31 is ≥90%.

4. The shear wave velocity determination method based on the multi-index interval matching decision scheme according to claim 1 is characterized in that: The specific steps of S33 are: select the one with the largest information gain rate among the multiple soil property indicators or test point depths obtained in S32 as the root decision node, and divide the branch subsets according to different discrete intervals in the root decision node; repeat the calculation of the information gain rate on the branch subsets and divide the sub-decision nodes until the leaf node matching is completed, and obtain the decision plan and the number of samples that meet the decision plan.

5. The shear wave velocity determination method based on the multi-index interval matching decision scheme according to claim 1 is characterized in that: In S34, the interval matching data set is recalculated by resetting the length of the discrete interval, the total number of the discrete intervals, or reducing the number of the soil property indicators.

6. The shear wave velocity determination method based on the multi-index interval matching decision scheme according to claim 1 is characterized in that: S4 includes the following steps: Obtain soil property indicators of the target area and the target test point depth According to the final decision plan obtained in step S3, the target discrete interval of the soil property index and the target test point depth is determined, and the target discrete interval is and ; Calculate the shear wave velocity of the target area : ； In the formula, is the number of target discrete intervals, min represents the lower limit of the discrete interval, and max represents the upper limit of the discrete interval; , are the calculation correction coefficients of soil property index and test point depth respectively, , , .

7. The shear wave velocity determination method based on the multi-index interval matching decision scheme according to claim 6 is characterized in that: The target discrete interval includes the target soil property index discrete interval, the target test layer center point depth discrete interval and the target test layer shear wave velocity discrete interval; wherein: The target soil property index discrete interval is the discrete interval into which the soil property index of the target area falls in the final decision-making scheme; The discrete interval of the depth of the center point of the test layer is the discrete interval within which the depth of the target test point falls in the final decision solution; The target test layer shear wave velocity discrete interval is the shear wave velocity discrete interval corresponding to the target soil property index discrete interval and the test layer center point depth discrete interval in the final decision plan.

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