Differential settlement risk calculation method, differential settlement risk calculation system, differential settlement risk calculation program, and recording medium

Abstract

To provide a differential settlement risk calculation method capable of improving the accuracy of a settlement calculation result without increasing the number of consolidation tests so much.SOLUTION: It is determined whether the degree of difference (variation) in the layer to be consolidated at the plurality of points is small, medium, or large based on a predetermined criterion (step SP7). When the degree of difference between the consolidation target layers at the plurality of points is determined to be small based on a predetermined criterion, for the consolidation target layer at each depth of the four corner positions at the plurality of points, without performing the compaction test, an estimated compression index Cc for each depth at the building center position estimated from the compression index Cc obtained by the compaction test at each depth of the compaction target layer at the building center position is substituted for the compression index Cc for each same depth at the four corner positions (step SP8), and the compaction settlement amount S and the inclination angle θ for each depth at the plurality of points are calculated by the Cc method (step SP10).SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a differential settlement risk calculation method, a differential settlement risk calculation system, a differential settlement risk calculation program, and a recording medium, which are performed based on the distribution of a consolidation target layer (a soft clay layer). [Background technology]

[0002] Traditionally, standard penetration tests (SPTs) have been conducted to confirm the depth and thickness of the consolidation target layer (soft clayey soil layer). Specifically, undisturbed soil samples (specimens) are taken at an intermediate depth of the consolidation target layer, and consolidation tests are conducted to determine soil constants such as the compression index Cc required for consolidation calculations. The amount of consolidation settlement is then calculated based on the results, and the risk of differential settlement after building construction is generally considered.

[0003] Patent Document 1 discloses a ground assessment method for determining whether ground reinforcement work is necessary for the target ground of a small building, which includes an embankment fill soil extraction step, a subsidence deformation analysis step, a bearing capacity analysis step, and a comprehensive assessment step, and takes into account compression settlement and consolidation settlement due to embankment load and building load for new embankment ground that has been developed less than two years ago, takes into account consolidation settlement due to embankment load and building load for new embankment ground that has been developed more than two years ago, takes into account compression settlement and consolidation settlement due to building load for new fill ground, and takes into account only consolidation settlement due to building load for other ground, and defines the estimated subsidence as the sum of the estimated compression settlement and the estimated consolidation settlement. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-3346 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, consolidation tests are conducted at a representative depth of the consolidation target layer (generally an intermediate depth) to obtain the compression index Cc and other values ​​required for consolidation calculations, and consolidation calculations are generally performed assuming that other depths are similar. However, in reality, the compression index Cc and other values ​​vary depending on the depth, so it is not possible to improve the accuracy of settlement calculation results. Furthermore, while increasing the number of consolidation tests would improve the accuracy of settlement calculation results, this is not realistic due to the high cost of ground investigation.

[0006] The objective of this invention is to provide a differential settlement risk calculation method, a differential settlement risk calculation system, a differential settlement risk calculation program, and a recording medium that enable improvement in the accuracy of settlement calculation results without significantly increasing the number of consolidation tests. [Means for solving the problem]

[0007] The method for calculating the risk of differential settlement of the present invention includes the steps of: confirming the distribution of consolidation target layers by conducting standard penetration tests at multiple points of a planned building; A step of conducting a consolidation test on specimens at three or more depths of the consolidation target layer at some of the multiple locations and determining at least a compression index Cc for each depth, When the degree of difference between the consolidation target layers at the above-mentioned multiple locations is determined to be small based on a predetermined standard, the method is characterized in that, without conducting consolidation tests for the consolidation target layers at locations other than the above-mentioned specific location, the estimated compression index Cc for each depth at the specific location estimated from the compression index Cc obtained in the consolidation test at each depth of the consolidation target layer at the above-mentioned specific location is used as the compression index Cc for each same depth at the above-mentioned specific location, and the consolidation settlement S and slope angle θ for each depth at the above-mentioned multiple locations are calculated.

[0008] With the above method, when the degree of difference between the consolidation target layers at the multiple locations is determined to be small based on a specified standard, consolidation tests are not conducted for the consolidation target layers at locations other than the selected location at the multiple locations. Instead, the estimated compression index Cc for each depth at the selected location, estimated from the compression index Cc obtained in the consolidation test at each depth of the consolidation target layer at the selected location, is used as the compression index Cc for the same depth at the other locations, and the consolidation settlement amount S and slope angle θ for each depth at the multiple locations are calculated.This improves the accuracy of the subsidence calculation results compared to a method in which the compression index Cc of the selected location is uniformly substituted for the consolidation target layers at the multiple locations.

[0009] The method for calculating the risk of differential settlement of the present invention includes the steps of: confirming the distribution of consolidation target layers by conducting standard penetration tests at multiple points of a planned building; A step of conducting a consolidation test on specimens at three or more depths of the consolidation target layer at some of the multiple locations and determining at least a compression index Cc for each depth, When the degree of difference in the consolidation target layers at the above-mentioned multiple locations is determined to be moderate based on a predetermined standard, the method is characterized in that, without conducting consolidation tests for the consolidation target layers at locations other than the above-mentioned certain locations at the above-mentioned multiple locations, an estimated compression index Cc for each depth at the above-mentioned other locations is calculated using the estimated compression index Cc for each depth at the above-mentioned certain locations estimated from the compression index Cc obtained in the consolidation test at each depth of the consolidation target layer at the above-mentioned certain locations, and the consolidation settlement S and slope angle θ for each depth at the above-mentioned multiple locations are calculated using the estimated compression index Cc for each depth at the above-mentioned certain locations.

[0010] With the above method, when the degree of difference in the consolidation target layers at the multiple locations is determined to be moderate based on specified criteria, without conducting consolidation tests for the consolidation target layers at locations other than the certain locations at the multiple locations, the estimated compression index Cc for each depth at the certain locations is calculated using the estimated compression index Cc for each depth at the certain locations estimated from the compression index Cc obtained in the consolidation test at each depth of the consolidation target layer at the certain locations, and the estimated compression index Cc for each depth at the other locations is used to calculate the consolidation settlement amount S and slope angle θ for each depth at the multiple locations.Therefore, the accuracy of the subsidence calculation results can be improved compared to a method in which the compression index Cc of the certain location is uniformly used for the consolidation target layers at the multiple locations.

[0011] The estimated compression index Cc for each depth at the partial location estimated from the compression index Cc obtained in the consolidation test at each depth of the consolidation target layer at the partial location may be calculated by applying the natural water content Wn measured from samples of the consolidation target layer at each depth at the partial location to an approximation formula obtained from the compression index Cc and natural water content Wn at each depth of the consolidation target layer at the partial location.

[0012] The estimated compression index Cc for each of the same depths at the other locations may be calculated by applying the natural moisture content Wn measured from samples of the consolidation target layer at each depth at the other locations to an approximate formula obtained from the compression index Cc and natural moisture content Wn at each depth of the consolidation target layer at the certain location.

[0013] As the predetermined criterion, at least one of the layer thickness H and the N value of the consolidation target layer at the plurality of points may be used.

[0014] The differential settlement risk calculation system of the present invention is a differential settlement risk calculation system that uses at least information on the distribution of the consolidation target layer confirmed by conducting standard penetration tests at multiple points of the planned building, and the compression index Cc calculated for each depth of the consolidation tests conducted on specimens at three or more depths of the consolidation target layer at some points among the multiple points, When the degree of difference between the consolidation target layers at the above-mentioned multiple locations is determined to be small based on a predetermined standard, the method is characterized in that, without conducting consolidation tests for the consolidation target layers at locations other than the above-mentioned specific location, the estimated compression index Cc for each depth at the specific location estimated from the compression index Cc obtained in the consolidation test at each depth of the consolidation target layer at the above-mentioned specific location is used as the compression index Cc for each same depth at the above-mentioned specific location, and the consolidation settlement S and slope angle θ for each depth at the above-mentioned multiple locations are calculated.

[0015] The differential settlement risk calculation system of the present invention is a differential settlement risk calculation system that uses at least information on the distribution of the consolidation target layer confirmed by conducting standard penetration tests at multiple points of the planned building, and the compression index Cc calculated for each depth of the consolidation tests conducted on specimens at three or more depths of the consolidation target layer at some points among the multiple points, When the degree of difference in the consolidation target layers at the above-mentioned multiple locations is determined to be moderate based on a predetermined standard, the method is characterized in that, without conducting consolidation tests for the consolidation target layers at locations other than the above-mentioned certain locations at the above-mentioned multiple locations, an estimated compression index Cc for each depth at the above-mentioned other locations is calculated using the estimated compression index Cc for each depth at the above-mentioned certain locations estimated from the compression index Cc obtained in the consolidation test at each depth of the consolidation target layer at the above-mentioned certain locations, and the consolidation settlement S and slope angle θ for each depth at the above-mentioned multiple locations are calculated using the estimated compression index Cc for each depth at the above-mentioned certain locations.

[0016] The differential subsidence risk calculation program of the present invention is characterized by causing an information processing device to execute the differential subsidence risk calculation system described above.

[0017] A recording medium according to the present invention is characterized in that it stores the differential subsidence risk calculation program described above. [Effects of the Invention]

[0018] The present invention has the effect of enabling the accuracy of settlement calculation results to be improved without significantly increasing the number of consolidation tests. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a flowchart showing a part of a differential subsidence risk calculation method according to an embodiment. [Figure 2] 10 is a flowchart showing another part of the differential subsidence risk calculation method according to the embodiment. [Figure 3] FIG. 1 is an explanatory diagram showing an example of a plot of the compression index Cc and the natural water content Wn. [Figure 4] FIG. 10 is an explanatory diagram illustrating a logarithm at the center of a building. [Figure 5] 1 is a schematic configuration diagram of an embodiment of an differential subsidence risk calculation system. DETAILED DESCRIPTION OF THE INVENTION

[0020] An embodiment of the present invention will be described below with reference to the accompanying drawings. Figures 1 and 2 are flowcharts showing an embodiment of a method for calculating the risk of differential settlement. In this method, standard penetration tests (SPTs) are conducted at multiple points on a planned building (step SP1). In this example, the multiple points are a total of five points, including the center position of the building and the four corner positions of the building, and some of the points among the multiple points are only the center position of the building, and the other points are the four corner positions of the building. By conducting the standard penetration tests, the N-value and soil quality of the ground can be detected, making it possible to determine whether the ground is hard or soft.

[0021] Next, it is determined whether the ground is solid and in good condition (step SP2), and if the ground is in good condition, the feasibility of a spread foundation is considered (step SP3). On the other hand, if it is determined that the ground is not in good condition, it is determined whether the ground is soft enough to require support piles (step SP4). If it is determined that the ground requires support piles, the feasibility of a pile foundation is considered (step SP5). On the other hand, if it is determined that the ground is not in good enough condition to require support piles, step SP6 is processed for the center position of the building.

[0022] In step SP6, (1) consolidation tests are conducted using specimens at three or more depths in the consolidation target layer (soft clayey soil layer) to determine the soil constants required for consolidation calculations, such as the compression index Cc. (2) The natural water content Wn is measured for samples taken within the consolidation target layer, for example, every 1 m, using an SPT sampler. (3) For three or more depths, the compression index Cc and natural water content Wn at the same depth are matched as shown in Figure 3, and the least squares method is applied to obtain the relationship (approximation) between Cc and Wn in Equation 1 (Equation 1: Cc = a × Wn + b). (4) For depths where consolidation tests have not been conducted, the measured natural water content Wn at each depth is applied to Equation 1 to calculate the estimated compression index Cc for each depth at the center of the building.

[0023] Figure 4 shows an example of a logarithm at the center of the building. In this example, the three depths mentioned above in each consolidation target layer are represented by black squares, and the depths where consolidation tests were not conducted (the depths where the estimated compression index Cc is calculated) are represented by black circles. There are two consolidation target layers.

[0024] After step SP6, the degree of difference (variation) between the consolidation target layers at the multiple locations is determined based on a predetermined criterion (step SP7). In this example, the predetermined criterion is the layer thickness difference between the consolidation target layers at each measurement point. For example, a layer thickness difference of 3 m or more is determined as "large," a layer thickness difference of 1 m or more but less than 3 m is determined as "medium," and a layer thickness difference of less than 1 m is determined as "small." The layer thickness difference can be determined, for example, by taking the difference between the layer thickness Hmax of the thickest measurement point and the layer thickness Hmin of the thinnest measurement point of the consolidation target layer, by taking the average difference between the layer thickness H at the center of the building and the layer thickness H at the four corner positions, or by taking the largest difference between the layer thickness H at the center of the building and the layer thickness H at the four corner positions. The predetermined criterion can also be the difference in N value between the consolidation target layers at each measurement point. Furthermore, the predetermined criterion can also be the combined value of the layer thickness difference and N value difference between the consolidation target layers at each measurement point.

[0025] If it is determined that the degree of difference in the consolidation target layers at the above multiple locations is small based on a predetermined standard, without conducting a consolidation test for the consolidation target layers at each depth at the four corner locations at the above multiple locations, the estimated compression index Cc for each depth at the center location of the building, estimated from the compression index Cc obtained in the consolidation test for each depth of the consolidation target layer at the center location of the building, is used as the compression index Cc for each same depth at the above four corner locations (step SP8), and the consolidation settlement S and slope angle θ for each depth at the above multiple locations are calculated using the Cc method (step SP10).

[0026] On the other hand, if in step SP7 the degree of difference in the consolidation target layers at the above multiple locations is determined to be moderate based on predetermined criteria, without conducting consolidation tests on the consolidation target layers at each depth at the four corner locations at the above multiple locations, the estimated compression index Cc for each depth at the center location of the building is used to calculate the estimated compression index Cc for each depth from samples taken with the SPT sampler at the above four corner locations using the above formula 1, without conducting consolidation tests on the consolidation target layers at each depth at the four corner locations (step SP9), and the estimated compression index Cc for each depth at the four corner locations is calculated using the Cc method (step SP10).

[0027] The calculation formula for the Cc method is as follows:

number

[0028] Next, it is determined whether the consolidation settlement amount S and the inclination angle θ for each depth at the above multiple points are within the allowable values ​​(step SP11). If the consolidation settlement amount S and the inclination angle θ are within the allowable values, the use of a spread foundation is considered (step SP12). On the other hand, if the consolidation settlement amount S and the inclination angle θ are not within the allowable values, the ground improvement method and specifications are selected (step SP13).

[0029] Then, for the selected construction method and specifications, the consolidation settlement amount S and the inclination angle θ for each depth at the multiple locations are calculated using the Cc method (step SP14), and it is again determined whether the consolidation settlement amount S and the inclination angle θ for each depth at the multiple locations are within the allowable values ​​(step SP15). If the consolidation settlement amount S and the inclination angle θ are within the allowable values, the selected ground improvement construction method and specifications are adopted. On the other hand, if the consolidation settlement amount S and the inclination angle θ are not within the allowable values, proceed to step SP13 to select a ground improvement construction method and specifications. Furthermore, if in step SP7 the degree of difference in the consolidation target layers at the multiple locations is determined to be large based on a predetermined standard, a separate review is conducted (step SP16).

[0030] With the above method, when the degree of difference between the consolidation target layers at the multiple locations is determined to be small based on a specified standard, consolidation tests are not conducted for the consolidation target layers at locations other than the selected location at the multiple locations. Instead, the estimated compression index Cc for each depth at the selected location, estimated from the compression index Cc obtained in the consolidation test at each depth of the consolidation target layer at the selected location, is used as the compression index Cc for the same depth at the other locations, and the consolidation settlement amount S and slope angle θ for each depth at the multiple locations are calculated.This improves the accuracy of the subsidence calculation results compared to a method in which the compression index Cc of the selected location is uniformly substituted for the consolidation target layers at the multiple locations.

[0031] In addition, in the above method, when the degree of difference in the consolidation target layers at the multiple locations is determined to be moderate based on a specified standard, without conducting consolidation tests for the consolidation target layers at locations other than the certain locations at the multiple locations, the estimated compression index Cc for each depth at the certain locations is calculated using the estimated compression index Cc for each depth at the certain locations estimated from the compression index Cc obtained in the consolidation test at each depth of the consolidation target layer at the certain locations, and the estimated compression index Cc for each depth at the certain locations is used to calculate the consolidation settlement amount S and slope angle θ for each depth at the multiple locations, thereby improving the accuracy of the subsidence calculation results compared to a method in which the compression index Cc of the certain location is uniformly used for the consolidation target layers at the multiple locations.

[0032] Furthermore, by conducting screw weight penetration tests (SWS) and dynamic cone penetration tests (SRS) at measurement points other than the four corners of the building, it is possible to inexpensively grasp the surface extent of the consolidation target layer and improve the accuracy of differential settlement risk assessment. Furthermore, accuracy can be further improved by increasing the number of consolidation tests conducted depending on the importance of the building, etc.

[0033] 5 is a block diagram showing a schematic configuration of an embodiment of a differential settlement risk calculation system 1. This differential settlement risk calculation system 1 is a system that uses at least information on the distribution of consolidation target layers confirmed by conducting standard penetration tests at multiple points on a planned building, and compression indexes Cc calculated for each depth in consolidation tests conducted on specimens at three or more depths of the consolidation target layers at some points (the center position of the building) among the multiple points, and includes an input unit 11, a memory unit 12 (recording medium), a processing unit 13 (information processing device), and an output unit 14.

[0034] The differential subsidence risk calculation system 1 performs, for example, at least the processes of steps SP6 (processing of (3) and (4)) to SP11 in the flowcharts shown in FIGS.

[0035] The input unit 11 allows input of the natural water content Wn of the consolidation target layer measured from samples collected at each measurement point and each depth. The memory unit 12 stores a differential settlement risk calculation program that causes the processing unit 13 to execute at least steps SP6 (processing of (3) and (4)) to SP11 described above. The processing unit 13 executes various processes based on the differential settlement risk calculation program read from the memory unit 12, determines variations in the layer thickness H and N value of the consolidation target layer at each measurement point, and determines whether the amount of consolidation settlement S and the inclination angle θ are within allowable values. The output unit 14 is, for example, a monitor, and displays a message such as "Consider spread foundation" in step SP12.

[0036] Although the embodiments of the present invention have been described above with reference to the drawings, the present invention is not limited to the illustrated embodiments. Various modifications and variations can be made to the illustrated embodiments within the same scope as the present invention or within an equivalent scope. [Explanation of symbols]

[0037] 1: Uneven settlement risk calculation system 11: Input section 12: Storage section 13: Processing section 14: Output section

Claims

1. A stage in which standard penetration tests are carried out at multiple points in the planned building to confirm the distribution of the consolidation target layers; and conducting a consolidation test on specimens at three or more depths of the consolidation target layer at some of the plurality of locations, and determining at least a compression index Cc for each depth; When the degree of difference in the consolidation target layers at the above-mentioned multiple locations is determined to be small based on a predetermined standard, a method for calculating the amount of consolidation settlement S and the slope angle θ for each depth at the above-mentioned multiple locations is performed, without conducting consolidation tests on the consolidation target layers at locations other than the above-mentioned multiple locations.The method is characterized by using the estimated compression index Cc for each depth at the above-mentioned multiple locations estimated from the compression index Cc obtained in the consolidation test at each depth of the consolidation target layer at the above-mentioned multiple locations as the compression index Cc for each same depth at the above-mentioned multiple locations, and calculating the amount of consolidation settlement S and the slope angle θ for each depth at the above-mentioned multiple locations.

2. A stage in which standard penetration tests are carried out at multiple points in the planned building to confirm the distribution of the consolidation target layers; and conducting a consolidation test on specimens at three or more depths of the consolidation target layer at some of the plurality of locations, and determining at least a compression index Cc for each depth; When the degree of difference in the consolidation target layers at the above-mentioned multiple locations is determined to be moderate based on predetermined criteria, a method for calculating an estimated compression index Cc for each depth at the above-mentioned multiple locations without conducting a consolidation test on the consolidation target layers at locations other than the above-mentioned multiple locations, using an estimated compression index Cc for each depth at the above-mentioned multiple locations estimated from the compression index Cc obtained in a consolidation test at each depth of the consolidation target layer at the above-mentioned multiple locations, and calculating the amount of consolidation settlement S and slope angle θ for each depth at the above-mentioned multiple locations using the estimated compression index Cc for each depth at the above-mentioned multiple locations.

3. In the method for calculating the risk of differential subsidence described in claim 1 or claim 2, the estimated compression index Cc for each depth of the partial point estimated from the compression index Cc obtained in a consolidation test at each depth of the consolidation target layer at the partial point is calculated by applying the natural water content Wn measured from samples of the consolidation target layer at each depth of the partial point to an approximation formula obtained from the compression index Cc at each depth of the consolidation target layer at the partial point and the natural water content Wn.

4. In the method for calculating the risk of differential subsidence described in claim 2, the estimated compression index Cc for each depth at the other locations is calculated by applying the natural water content Wn measured from samples of the consolidation target layer for each depth at the other locations to an approximation formula obtained from the compression index Cc and natural water content Wn at each depth of the consolidation target layer at the certain locations.

5. A method for calculating the risk of differential subsidence as described in claim 1 or claim 2, characterized in that at least one of the layer thickness H and N value of the consolidation target layer at the multiple points is used as the specified criterion.

6. A differential settlement risk calculation system that uses at least information on the distribution of consolidation target layers confirmed by conducting standard penetration tests at multiple points of a planned building, and a compression index Cc calculated for each depth of a consolidation test conducted on specimens at three or more depths of the consolidation target layers at some points among the multiple points, When the degree of difference in the consolidation target layers at the above-mentioned multiple locations is determined to be small based on a predetermined standard, an differential subsidence risk calculation system is characterized in that, without conducting consolidation tests for the consolidation target layers at locations other than the above-mentioned specific locations at the above-mentioned multiple locations, the estimated compression index Cc for each depth at the specific location estimated from the compression index Cc obtained in the consolidation test at each depth of the consolidation target layer at the above-mentioned specific location is used as the compression index Cc for each same depth at the above-mentioned specific locations, and the consolidation settlement amount S and slope angle θ for each depth at the above-mentioned multiple locations are calculated.

7. A differential settlement risk calculation system that uses at least information on the distribution of consolidation target layers confirmed by conducting standard penetration tests at multiple points of a planned building, and a compression index Cc calculated for each depth of a consolidation test conducted on specimens at three or more depths of the consolidation target layers at some points among the multiple points, When the degree of difference in the consolidation target layers at the above-mentioned multiple locations is determined to be moderate based on predetermined criteria, an differential subsidence risk calculation system is provided which, without conducting consolidation tests for the consolidation target layers at locations other than the above-mentioned certain locations at the above-mentioned multiple locations, calculates an estimated compression index Cc for each depth at the above-mentioned other locations using an estimated compression index Cc for each depth at the above-mentioned certain locations estimated from the compression index Cc obtained in a consolidation test at each depth of the consolidation target layer at the above-mentioned certain locations, and calculates the consolidation settlement amount S and slope angle θ for each depth at the above-mentioned multiple locations using the estimated compression index Cc for each depth at the above-mentioned certain locations.

8. A differential subsidence risk calculation program that causes an information processing device to execute the differential subsidence risk calculation system according to claim 6 or 7.

9. A recording medium storing the differential subsidence risk calculation program according to claim 8.

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