Foundation soil bearing capacity comprehensive valuing method

Abstract

The invention relates to the technical field of geotechnical engineering investigation, in particular to a foundation soil bearing capacity comprehensive valuing method which comprises the following steps: S1, acquiring calculation results of various methods for calculating foundation soil bearing capacity; s2, assigning and scoring the calculation result of each method by adopting a plurality of evaluation indexes, and summing scores of the evaluation indexes to obtain a total evaluation score of the calculation result of each method; s3, obtaining a value coefficient of the calculation result of each method according to the total evaluation score of the calculation result of each method; and S4, performing weighted calculation on calculation results of the methods and value coefficients of the calculation results of the methods to obtain a comprehensive value of the bearing capacity of the foundation soil. Overestimation or underestimation possibly existing when a single method is used for calculating the bearing capacity of the foundation soil can be effectively avoided, so that engineering is safe, and the bearing capacity of the foundation soil can be fully utilized.

Description

Technical Field

[0001] The present invention relates to the technical field of geotechnical engineering investigation, and particularly to a comprehensive value-taking method for the bearing capacity of foundation soil. Background Art

[0002] The bearing capacity of foundation soil refers to the ability of the foundation soil to bear the load per unit area, and the bearing capacity of foundation soil is an extremely important fundamental issue in foundation engineering. There are various methods or means to obtain the bearing capacity of foundation soil, such as obtaining it through on-site load tests, using in-situ test results or calculating with indoor shear strength indexes, etc.

[0003] In most geotechnical engineering investigation projects, multiple investigation means are adopted. According to the investigation data collected by various investigation means, multiple methods for calculating the bearing capacity of foundation soil can be correspondingly used to calculate the bearing capacity of foundation soil respectively, and there are differences in the calculation results of different methods. For the value-taking of the bearing capacity of foundation soil, if only the lowest value among the calculation results of multiple methods is taken, the bearing capacity of the foundation soil cannot be fully utilized, resulting in an increase in the engineering construction cost; if only the calculation result of one of the multiple methods is adopted, the value-taking is too limited and the accuracy of the result cannot be guaranteed; if the average value of the calculation results of multiple methods is adopted, the differences between different methods are ignored. Summary of the Invention

[0004] In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is to provide a comprehensive value-taking method for the bearing capacity of foundation soil, which can improve the accuracy of the value-taking of the bearing capacity of foundation soil based on multiple methods for calculating the bearing capacity of foundation soil in geotechnical engineering investigation, making the project both safe and able to fully utilize the bearing capacity of the foundation soil.

[0005] To solve the above technical problem, the present invention adopts the following technical solutions:

[0006] The present invention provides a comprehensive value-taking method for the bearing capacity of foundation soil, which successively includes the following steps:

[0007] Step S1, obtaining the calculation results of multiple methods for calculating the bearing capacity of foundation soil;

[0008] Step S2, respectively assigning values, scoring to the calculation results of each method with multiple evaluation indexes and summing the scores of each evaluation index to obtain the total evaluation score of the calculation result of each method;

[0009] Step S3, obtaining the value-taking coefficient of the calculation result of each method according to the total evaluation score of the calculation result of each method;

[0010] Step S4, performing weighted calculation on the calculation results of each method and the value-taking coefficients of the calculation results of each method to obtain the comprehensive value-taking of the bearing capacity of foundation soil.

[0011] Preferably, step S1 includes:

[0012] Step S1a: Determine multiple methods for calculating the bearing capacity of foundation soil, and collect the data required for calculating the bearing capacity of foundation soil by each method.

[0013] Step S1b: Process the data of each method and calculate the bearing capacity of foundation soil to obtain the calculation results of each method.

[0014] Preferably, in step S1b, the calculation results of each method are unified into the same type of bearing capacity of foundation soil.

[0015] Preferably, in step S2, at least two-level evaluation indicators are used to grade and assign values to the calculation results of each method, and the scores of the lowest-level evaluation indicators are summed up.

[0016] Preferably, in step S3, the ratio of the total evaluation score of the calculation results of each method to the sum of the total evaluation scores of the calculation results of all methods is used as the value coefficient of the calculation results of each method.

[0017] Preferably, in step S4, the sum of the products of the calculation results of each method and the value coefficients of the calculation results of each method is used as the comprehensive value of the bearing capacity of foundation soil.

[0018] Compared with the prior art, the present invention has significant progress:

[0019] The comprehensive value method of the bearing capacity of foundation soil of the present invention comprehensively considers multiple different methods for calculating the bearing capacity of foundation soil. Multiple evaluation indicators are respectively used to assign values and evaluate and score the calculation results of different methods according to the actual situation, and different value coefficients are given to the calculation results of different methods accordingly. The comprehensive value of the bearing capacity of foundation soil is obtained through the weighted calculation of the calculation results and value coefficients of each method. The value coefficients of the calculation results of each method are the coefficients after full evaluation of each method, and the results are objective and reliable, closer to the engineering reality. The comprehensive value of the bearing capacity of foundation soil obtained can effectively avoid the possible overestimation or underestimation of calculating the bearing capacity of foundation soil by a single method, can not only avoid the limitations of using a single method to calculate the bearing capacity of foundation soil, make the value result of the bearing capacity of foundation soil more reasonable, and reduce the engineering construction risk, but also avoid the problem of excessive conservatism of taking the lowest value of the calculation results of multiple methods as the value of the bearing capacity of foundation soil, resulting in an increase in engineering construction costs. Thus, the project is both safe and can make full use of the bearing capacity of the foundation soil. Description of the Drawings

[0020] Figure 1 is a schematic flow chart of the comprehensive value method of the bearing capacity of foundation soil in an embodiment of the present invention. Detailed Embodiments

[0021] The following further elaborates on the specific embodiments of the present invention in conjunction with the accompanying drawings. These embodiments are only used to illustrate the present invention and are not intended to limit the present invention.

[0022] In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more.

[0023] As Figure 1 shown, it is an embodiment of the comprehensive value-taking method for the bearing capacity of foundation soil provided by the present invention. The comprehensive value-taking method for the bearing capacity of foundation soil in this embodiment sequentially includes the following steps S1 - S4.

[0024] Step S1: Obtain the calculation results of various methods for calculating the bearing capacity of foundation soil.

[0025] Preferably, step S1 includes the following steps S1a - S1b.

[0026] Step S1a: Determine various methods for calculating the bearing capacity of foundation soil, and collect the data required for each method to calculate the bearing capacity of foundation soil.

[0027] Specifically, obtain the methods and means for geotechnical engineering investigation in a geotechnical engineering investigation project, and accordingly determine the methods that can be used to calculate the bearing capacity of foundation soil. After clarifying various methods for calculating the bearing capacity of foundation soil, collect the corresponding data required for calculating the bearing capacity of foundation soil.

[0028] The investigation methods that can be used to calculate the bearing capacity of foundation soil include in-situ tests, laboratory geotechnical tests, etc. According to the investigation method means used in the geotechnical engineering investigation project, after determining the in-situ tests, laboratory geotechnical tests and other investigation method means that can be used to calculate the bearing capacity of foundation soil, collect the data required for the in-situ tests, laboratory geotechnical tests and other investigation method means to calculate the bearing capacity of foundation soil.

[0029] For example, when a geotechnical engineering investigation project uses investigation methods and means such as standard penetration test, static cone penetration test and laboratory shear test for investigation, methods such as standard penetration blow count, static cone penetration tip resistance and laboratory shear test shear strength can be used to calculate the bearing capacity of foundation soil. After clarifying the methods for calculating the bearing capacity of foundation soil, specifically collect data such as standard penetration blow count, tip resistance, sidewall friction resistance, cohesion and shear strength of the foundation soil.

[0030] Step S1b: Process the data of each method and calculate the bearing capacity of foundation soil to obtain the calculation results of each method.

[0031] Specifically, the processing of the collected data includes the elimination, correction of outliers and statistical calculations. The average value, coefficient of variation, standard deviation, correction coefficient, standard value, etc. are obtained through the statistical calculations of the collected data. If the values such as the coefficient of variation calculated statistically exceed the set range, the data with large deviations are eliminated until the required coefficient of variation is met. After the data processing, the average value or the standard value is used to calculate the bearing capacity of the foundation soil by each method, and the calculation results of each method are obtained.

[0032] Preferably, in step S1b, the calculation results of each method are unified into the same type of bearing capacity of the foundation soil. When the bearing capacities of the foundation soil calculated by the methods for calculating the bearing capacity of the foundation soil are of different types of bearing capacities, they should be unified into the same type of bearing capacity of the foundation soil according to the design information, etc. and used as the calculation result of this method.

[0033] In step S2, a variety of evaluation indexes are respectively used to assign values, score and sum the scores of each evaluation index for the calculation results of each method, so as to obtain the total evaluation score of the calculation results of each method.

[0034] Specifically, the same or different total scores are assigned to each method for calculating the bearing capacity of the foundation soil, and the total score is the highest score that this method can obtain.

[0035] The calculation results of each method are assigned values from a variety of different evaluation indexes, and the assigned value is the highest score that this type of evaluation index can obtain. The sum of the assigned values of all evaluation indexes of each method is equal to the total score assigned to this method. Subsequently, each evaluation index is scored according to the actual situation, and the scored value of each evaluation index does not exceed its assigned value. After the scoring is completed, the scores of all evaluation indexes of each method are summed to obtain the total evaluation score of the calculation results of each method.

[0036] Preferably, in step S2, at least two levels of evaluation indicators are used to grade and assign values to the calculation results of each method, and the scores of the lowest-level evaluation indicators are summed up. Specifically, for the calculation results of each method, values are assigned from multiple different first-level evaluation indicators, and the sum of the values of all the first-level evaluation indicators of each method is equal to the total score assigned to this method; for each first-level evaluation indicator, values are assigned from multiple different second-level evaluation indicators, and the sum of the values of all the second-level evaluation indicators of each first-level evaluation indicator is equal to the value of this first-level evaluation indicator; according to the characteristics of each method, each second-level evaluation indicator can also be further graded and assigned values. Thus, after the grading and value assignment are completed, the scores of all the lowest-level evaluation indicators of each method are summed up, so as to obtain the evaluation total scores of the calculation results of each method. For example, when two-level evaluation indicators are adopted, the scores of all the second-level evaluation indicators of each method are summed up, and the sum of the scores of all the second-level evaluation indicators of each first-level evaluation indicator is the score of this first-level evaluation indicator, and the sum of the scores of all the first-level evaluation indicators of each method is the evaluation total score of the calculation results of each method. By using the method of multi-level evaluation indicator assignment and scoring, the methods for calculating the bearing capacity of foundation soil can be fully and completely evaluated, providing a basis for the comprehensive value-taking of the bearing capacity of foundation soil.

[0037] Preferably, the first-level evaluation indicators include but are not limited to operation reliability, data collection, and calculation method reliability. Among them, the second-level evaluation indicators of the first-level evaluation indicator reliability include but are not limited to operation environment, operation standardization, and personnel proficiency; the second-level evaluation indicators of the first-level evaluation indicator data collection include but are not limited to data quantity and data quality; the second-level evaluation indicators of the first-level evaluation indicator calculation method reliability include but are not limited to method application universality and method theory. According to needs, more levels of evaluation indicators can also be further divided for each second-level evaluation indicator.

[0038] Step S3, according to the evaluation total scores of the calculation results of each method, obtain the value-taking coefficients of the calculation results of each method.

[0039] Preferably, in step S3, the proportion of the evaluation total score of the calculation result of each method in the sum of the evaluation total scores of the calculation results of all methods is used as the value-taking coefficient of the calculation result of each method.

[0040] Specifically, sum up the evaluation total scores of the calculation results of all methods, and divide the evaluation total score of the calculation result of each method by the sum of the evaluation total scores of the calculation results of all methods, so as to obtain the value-taking coefficients of the calculation results of each method.

[0041] For example, if the total evaluation scores of the calculation results of three methods for calculating the bearing capacity of foundation soil, namely the standard penetration test, the static cone penetration test, and the indoor shear test, are a, b, and c respectively, then the value-taking coefficients of the calculation results of the standard penetration test, the static cone penetration test, and the indoor shear test are a / (a + b + c), b / (a + b + c), and c / (a + b + c) respectively.

[0042] Step S4: Perform weighted calculation on the calculation results of each method and the value-taking coefficients of the calculation results of each method to obtain the comprehensive value of the bearing capacity of foundation soil.

[0043] Preferably, in step S4, the sum of the products of the calculation results of each method and the value-taking coefficients of the calculation results of each method is used as the comprehensive value of the bearing capacity of foundation soil.

[0044] Specifically, multiply the calculation result of each method by the value-taking coefficient of the calculation result and then add them up to obtain the comprehensive value of the bearing capacity of foundation soil.

[0045] For example, if the calculation results of three methods for calculating the bearing capacity of foundation soil, namely the standard penetration test, the static cone penetration test, and the indoor shear test, are f1, f2, and f3 respectively, and the value-taking coefficients of the calculation results are a / (a + b + c), b / (a + b + c), and c / (a + b + c) respectively, then the final comprehensive value of the bearing capacity of foundation soil is f1×a / (a + b + c) + f2×b / (a + b + c) + f3×c / (a + b + c).

[0046] The comprehensive value-taking method for the bearing capacity of foundation soil in this embodiment comprehensively considers multiple different methods for calculating the bearing capacity of foundation soil. For the calculation results of different methods, multiple evaluation indicators are used for assignment and evaluation scoring according to the actual situation, and different value-taking coefficients are assigned to the calculation results of different methods accordingly. The comprehensive value of the bearing capacity of foundation soil is obtained through weighted calculation of the calculation results and value-taking coefficients of each method. The value-taking coefficients of the calculation results of each method are coefficients after full evaluation of each method. The result is objective and reliable, closer to the engineering practice. The obtained comprehensive value of the bearing capacity of foundation soil can effectively avoid the possible overestimation or underestimation of calculating the bearing capacity of foundation soil by a single method, can avoid the limitations of using a single method to calculate the bearing capacity of foundation soil, make the value-taking result of the bearing capacity of foundation soil more reasonable, reduce the engineering construction risk, and can also avoid the problem of excessive conservatism caused by taking the lowest value of the calculation results of multiple methods as the value of the bearing capacity of foundation soil, resulting in an increase in engineering construction costs. Thus, the project is both safe and can make full use of the bearing capacity of the foundation soil.

[0047] In a specific implementation, in a geotechnical engineering investigation project, a silty clay layer was investigated using investigation methods and means such as a standard penetration test, a single-bridge static penetration test, an indoor physical property test, and a consolidation quick shear test. When the comprehensive method for determining the bearing capacity of foundation soil of this embodiment is used, the following steps are specifically included.

[0048] Step S1a, determine that the results of the standard penetration test, the single bridge static penetration test and the consolidation quick shear test can be used to calculate the bearing capacity of the foundation soil. Collect the standard penetration blows of the standard penetration test of the silty clay layer, the specific penetration resistance data of the single bridge static penetration test, and the cohesion and internal friction angle data of the consolidation quick shear test, and also collect the foundation design width, the weight of all soil layers above the bottom surface of the foundation, and the weight of the soil layer below the foundation.

[0049] Step S1b, the collected data are subjected to obvious abnormal data elimination and statistical calculation, and the bearing capacity of the foundation soil is calculated respectively using the standard values ​​of the data collected by each method, the physical parameters of the soil, and the foundation design parameters. The bearing capacity of the foundation soil calculated by the standard penetration test is 98 kPa, the bearing capacity of the foundation soil calculated by the single bridge static penetration test is 87 kPa, and the bearing capacity of the foundation soil calculated by the consolidation quick shear test is 82 kPa.

[0050] Step S2, assign 30 points to the calculation results of the three methods respectively. Among them, the calculation results of the standard penetration test method and the single bridge static penetration test method are assigned 10 points respectively from the three first-level evaluation indicators of operation reliability, collection data and calculation method reliability, among which the operation reliability is assigned 3 points, 5 points and 2 points respectively from the three second-level evaluation indicators of operation environment, operation standardization and personnel proficiency; the collection data is assigned 4 points and 6 points respectively from the two second-level evaluation indicators of data quantity and data quality; the calculation method reliability is assigned 5 points and 5 points respectively from the two second-level evaluation indicators of method application breadth and method theory. The calculation results of the consolidation quick shear test method are assigned 10 points from the three first-level evaluation indicators of test reliability, data collection and calculation method reliability. Among them, the test reliability is assigned 5 points, 4 points and 1 point from the three second-level evaluation indicators of soil sample quality, test standardization and personnel proficiency respectively; the data collection is assigned 4 points and 6 points from the two second-level evaluation indicators of data quantity and data quality respectively, and the reliability of the calculation method is assigned 4 points, 4 points and 2 points from the three second-level evaluation indicators of method application breadth, method theory and the degree of test restoration of the original state of soil samples respectively. According to the inspection and review of the contents involved in each second-level evaluation indicator, each second-level evaluation indicator is scored separately, and then the scores of all the second-level evaluation indicators of the calculation results of the three methods are summed up respectively. Finally, the total evaluation score of the calculation results of the standard penetration test method is 20, the total evaluation score of the calculation results of the single bridge static penetration test method is 26.5, and the total evaluation score of the calculation results of the consolidation quick shear test method is 25.5.

[0051] Step S3: Sum up the evaluation total scores of the calculation results of the three methods, and divide the evaluation total score of the calculation result of each method by the sum of the evaluation total scores of the calculation results of all methods, obtaining the value coefficients of the calculation results of the standard penetration test method, the single bridge static cone penetration test method, and the consolidated quick shear test method as 0.278, 0.368, and 0.354 respectively.

[0052] Step S4: Multiply the calculation results of the standard penetration test method, the single bridge static cone penetration test method, and the consolidated quick shear test method (98 kPa, 87 kPa, and 82 kPa respectively) by the corresponding value coefficients of the calculation results (0.278, 0.368, and 0.354 respectively), and then sum them up to obtain the comprehensive value of the bearing capacity of silty clay as 88.3 kPa.

[0053] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and replacements can be made, and these improvements and replacements should also be regarded as the protection scope of the present invention.

Claims

1. A method for comprehensively determining the bearing capacity of foundation soil, characterized in that: The following steps are included in sequence: Step S1, obtaining calculation results of multiple methods for calculating the bearing capacity of foundation soil; Step S2: using a plurality of evaluation indicators to assign values ​​and score the calculation results of each method, and summing up the scores of each evaluation indicator to obtain the total evaluation score of the calculation results of each method; Step S3, obtaining the value coefficient of the calculation result of each method according to the total evaluation score of the calculation result of each method; Step S4: weighted calculation is performed on the calculation results of each method and the value coefficients of the calculation results of each method to obtain a comprehensive value of the bearing capacity of the foundation soil.

2. The method for obtaining the comprehensive value of foundation soil bearing capacity according to claim 1, characterized in that: The step S1 comprises: Step S1a, determining multiple methods for calculating the bearing capacity of foundation soil, and collecting data required for calculating the bearing capacity of foundation soil by each method; Step S1b: Process the data of each method and calculate the bearing capacity of the foundation soil to obtain the calculation results of each method.

3. The method for obtaining the comprehensive value of foundation soil bearing capacity according to claim 2, characterized in that: In the step S1b, the calculation results of each method are unified into the same type of foundation soil bearing capacity.

4. The method for obtaining the comprehensive value of foundation soil bearing capacity according to claim 1, characterized in that: In the step S2, the calculation results of each method are graded and assigned using at least two levels of evaluation indicators, and the lowest level of evaluation indicators are scored and the scores are summed.

5. The method for obtaining the comprehensive value of foundation soil bearing capacity according to claim 1, characterized in that: In step S3, the ratio of the total evaluation score of the calculation result of each method to the total evaluation score of the calculation results of all methods is used as the value coefficient of the calculation result of each method.

6. The method for obtaining the comprehensive value of foundation soil bearing capacity according to claim 1, characterized in that: In step S4, the comprehensive value of the bearing capacity of the foundation soil is obtained by summing the product of the calculation results of each method and the value coefficient of the calculation results of each method.

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