阅读说明：本技术 一种消除不同试验之间差异性的地基承载力确定方法 (Foundation bearing capacity determination method for eliminating difference among different tests ) 是由 赵斌臣 于 2020-05-29 设计创作，主要内容包括：本发明提供了一种消除不同试验之间差异性的地基承载力确定方法,本发明利用扁铲侧胀试验得到了试验区内地基承载力特征值,以此为依据,并分别以静力触探试验、标准贯入试验和室内土工试验结果中的承载力确定参数为变量,对于静力触探和标准贯入试验采用一元线性回归的方法建立关系公式,对于室内土工试验采用多元逐步回归的方法建立关系公式,从而消除不同试验方法得到的承载力值存在较大差异性的问题,能够快速、准确的确定该试验区内的地基承载力,无需长时期和大范围的现场观察测试,减少人工投入,降低花费。(The invention provides a foundation bearing capacity determining method for eliminating differences among different tests, which utilizes a flat shovel lateral expansion test to obtain a characteristic value of foundation bearing capacity in a test area, takes the characteristic value as a basis, and respectively takes bearing capacity determining parameters in results of a static penetration test, a standard penetration test and an indoor geotechnical test as variables, adopts a unitary linear regression method to establish a relational formula for the static penetration test and the standard penetration test, and adopts a multivariate stepwise regression method to establish the relational formula for the indoor geotechnical test, thereby eliminating the problem that the bearing capacity values obtained by different test methods have larger differences, being capable of quickly and accurately determining the foundation bearing capacity in the test area, needing no long-term and large-scale field observation and test, reducing labor input and reducing cost.)

1. A method for determining the bearing capacity of a foundation for eliminating the differences between different tests, characterized in that it comprises the following operations:

s1, determining the characteristic value of the bearing capacity of the foundation of each soil layer by using a flat shovel lateral expansion test;

s2, selecting static sounding test data, replacing the actual foundation bearing capacity value with the characteristic value of the foundation bearing capacity of the corresponding soil layer, and establishing the relation between the foundation bearing capacity and the specific penetration resistance by unitary linear regression;

s3, selecting standard penetration test data, replacing the actual foundation bearing capacity value with the characteristic value of the foundation bearing capacity of the corresponding soil layer, and establishing the relation between the foundation bearing capacity and the standard penetration hammering number by unitary linear regression;

s4, selecting indoor geotechnical test data, replacing the actual foundation bearing capacity value with the characteristic value of the foundation bearing capacity of the corresponding soil layer, and establishing the relation between the foundation bearing capacity and the porosity ratio and the liquidity index through multiple stepwise regression.

2. The method for determining foundation bearing capacity for eliminating differences among different tests according to claim 1, wherein the static sounding test specifically comprises:

the static touch probe is pressed into the foundation soil by using a hydraulic or mechanical transmission device, a resistance strain gauge is attached in the probe, when the probe is blocked, the resistance strain gauge is extended to change the resistance, a resistance strain instrument is used for measuring the numerical value of micro-strain, and the size of the penetration resistance is calculated, so that the engineering property of the foundation soil is judged.

3. The method for determining foundation bearing capacity to eliminate difference between different tests according to claim 2, wherein the static sounding is a single-bridge static sounding.

4. The method for determining foundation bearing capacity for eliminating difference between different tests according to claim 1, wherein the SPT specifically comprises:

the cylindrical probe with certain mass is intermittently injected with a certain length of drop distance, engineering property parameters of the foundation soil are judged according to the hammering number of each shot with a certain length, and mechanical layering is carried out on the foundation soil.

5. The method for determining foundation bearing capacity for eliminating difference between different tests according to claim 1, wherein the indoor geotechnical test is specifically as follows:

and arranging a test field area near the drill hole, continuously sampling within a range of 3 meters below the ground surface by using a thin-wall soil sampler and adopting a rapid static continuous pressing method, and performing a conventional soil test and a particle size test on the soil sample.

6. The method for determining foundation bearing capacity for eliminating difference between different tests as claimed in claim 1, wherein the relationship between the foundation bearing capacity and the specific penetration resistance is specifically as follows:

for silt, the calculation formula is as follows:

σ_O＝0.031P_S+0.098

in the formula, σ_OIs the bearing capacity value of the foundation, P_sSpecific penetration resistance;

for subsoil, the calculation formula is as follows:

σ_O＝0.0465P_S+0.0821

in the formula, σ_OIs the bearing capacity value of the foundation, P_sSpecific penetration resistance;

for loam, the calculation is as follows:

σ_O＝0.051P_S+0.0648

in the formula, σ_OIs the bearing capacity value of the foundation, P_sSpecific penetration resistance;

for clay, the calculation is as follows:

σ_O＝0.125P_S+0.016

in the formula, σ_OIs the bearing capacity value of the foundation, P_sSpecific penetration resistance;

for mucky soil, the calculation formula is as follows:

σ_O＝0.116P_S+0.022

in the formula, σ_OIs the bearing capacity value of the foundation, P_sThe specific penetration resistance was obtained.

7. The method for determining bearing capacity of foundation for eliminating difference between different tests according to claim 1, wherein the relationship between the bearing capacity of foundation and the normalized penetration hammering number is specifically as follows:

for silt, the calculation formula is as follows:

σ_O＝7.874N+51.34

in the formula, σ_OThe bearing capacity of the foundation is adopted, and N is the standard penetration hammering number;

for subsoil, the calculation formula is as follows:

σ_O＝10.232N+135.4

in the formula, σ_OThe bearing capacity of the foundation is adopted, and N is the standard penetration hammering number;

for loam, the calculation is as follows:

σ_O＝8.663N+110.98

in the formula, σ_OThe bearing capacity of the foundation is shown, and N is the standard penetration hammering number.

8. The method for determining foundation bearing capacity for eliminating differences among different tests according to claim 1, wherein the relationship between foundation bearing capacity and porosity ratio and liquidity index is as follows:

for subsoil, the calculation formula is as follows:

σ_O＝-71.31e+83.59I_L+252.04

in the formula, σ_OIs foundation bearing capacity, e is void ratio, I_LIs a liquidity index;

for loam, the calculation is as follows:

σ_O＝-11.94e-59.72I_L+287.05

in the formula, σ_OIs the bearing capacity of the foundation, e is the void ratio,I_Lis a liquidity index.

Technical Field

The invention relates to the technical field of foundation bearing capacity, in particular to a foundation bearing capacity determination method for eliminating differences among different tests.

Background

The problem of determining the bearing capacity of the foundation is a complex problem, although the determination method in the traditional sense is quite mature, the traditional method has a large number of assumptions, and geological backgrounds of all places are different, so that the bearing capacity of the foundation used in many practical projects at present is lower or higher, and unnecessary waste or engineering hidden troubles are caused.

The analysis and experimental study of the problem are performed on the basis of a large amount of existing field observation data, and the field observation test for a long period and a large range is labor-intensive, expensive and difficult to realize. It is therefore necessary to determine the bearing capacity of the foundation in a targeted manner.

Due to different test principles, the different test methods have different bases for judging soil body damage, so that the bearing force values determined by the different test methods have great difference, and great inconvenience is brought to scientific research work and engineering practice.

Disclosure of Invention

The invention aims to provide a foundation bearing capacity determining method for eliminating differences among different tests, and aims to solve the problem that the bearing capacity values obtained by different test methods in the prior art have large differences, quickly and accurately determine the foundation bearing capacity in a test area, reduce the labor investment and reduce the cost.

In order to achieve the technical purpose, the invention provides a foundation bearing capacity determination method for eliminating differences among different tests, which comprises the following operations:

s1, determining the characteristic value of the bearing capacity of the foundation of each soil layer by using a flat shovel lateral expansion test;

s2, selecting static sounding test data, replacing the actual foundation bearing capacity value with the characteristic value of the foundation bearing capacity of the corresponding soil layer, and establishing the relation between the foundation bearing capacity and the specific penetration resistance by unitary linear regression;

s3, selecting standard penetration test data, replacing the actual foundation bearing capacity value with the characteristic value of the foundation bearing capacity of the corresponding soil layer, and establishing the relation between the foundation bearing capacity and the standard penetration hammering number by unitary linear regression;

s4, selecting indoor geotechnical test data, replacing the actual foundation bearing capacity value with the characteristic value of the foundation bearing capacity of the corresponding soil layer, and establishing the relation between the foundation bearing capacity and the porosity ratio and the liquidity index through multiple stepwise regression.

Preferably, the static cone penetration test specifically comprises:

the static touch probe is pressed into the foundation soil by using a hydraulic or mechanical transmission device, a resistance strain gauge is attached in the probe, when the probe is blocked, the resistance strain gauge is extended to change the resistance, a resistance strain instrument is used for measuring the numerical value of micro-strain, and the size of the penetration resistance is calculated, so that the engineering property of the foundation soil is judged.

Preferably, the static sounding is a single bridge static sounding.

Preferably, the SPT is specifically:

the cylindrical probe with certain mass is intermittently injected with a certain length of drop distance, engineering property parameters of the foundation soil are judged according to the hammering number of each shot with a certain length, and mechanical layering is carried out on the foundation soil.

Preferably, the indoor geotechnical test specifically comprises:

and arranging a test field area near the drill hole, continuously sampling within a range of 3 meters below the ground surface by using a thin-wall soil sampler and adopting a rapid static continuous pressing method, and performing a conventional soil test and a particle size test on the soil sample.

Preferably, the relationship between the foundation bearing capacity and the specific penetration resistance is specifically as follows:

for silt, the calculation formula is as follows:

σ_O＝0.031P_S+0.098

in the formula, σ_OIs the bearing capacity value of the foundation, P_sSpecific penetration resistance;

for subsoil, the calculation formula is as follows:

σ_O＝0.0465P_S+0.0821

in the formula, σ_OIs the bearing capacity value of the foundation, P_sSpecific penetration resistance;

for loam, the calculation is as follows:

σ_O＝0.051P_S+0.0648

in the formula, σ_OIs the bearing capacity value of the foundation, P_sSpecific penetration resistance;

for clay, the calculation is as follows:

σ_O＝0.125P_S+0.016

in the formula, σ_OIs the bearing capacity value of the foundation, P_sSpecific penetration resistance;

for mucky soil, the calculation formula is as follows:

σ_O＝0.116P_S+0.022

in the formula, σ_OIs the bearing capacity value of the foundation, P_sThe specific penetration resistance was obtained.

Preferably, the relationship between the bearing capacity of the foundation and the penetration hammering number is specifically as follows:

for silt, the calculation formula is as follows:

σ_O＝7.874N+51.34

in the formula, σ_OThe bearing capacity of the foundation is adopted, and N is the standard penetration hammering number;

for subsoil, the calculation formula is as follows:

σ_O＝10.232N+135.4

in the formula, σ_OThe bearing capacity of the foundation is adopted, and N is the standard penetration hammering number;

for loam, the calculation is as follows:

σ_O＝8.663N+110.98

in the formula, σ_OThe bearing capacity of the foundation is shown, and N is the standard penetration hammering number.

Preferably, the relationship between the foundation bearing capacity and the porosity ratio and the liquidity index is as follows:

for subsoil, the calculation formula is as follows:

σ_O＝-71.31e+83.59I_L+252.04

in the formula, σ_OIs foundation bearing capacity, e is void ratio, I_LIs a liquidity index;

for loam, the calculation is as follows:

σ_O＝-11.94e-59.72I_L+287.05

in the formula, σ_OIs foundation bearing capacity, e is void ratio, I_LIs a liquidity index.

Drawings

Fig. 1 is a flowchart of a method for determining foundation bearing capacity to eliminate differences between different tests according to an embodiment of the present invention.

Detailed Description

In order to clearly explain the technical features of the present invention, the following detailed description of the present invention is provided with reference to the accompanying drawings. The following disclosure provides many different embodiments, or examples, for implementing different features of the invention. To simplify the disclosure of the present invention, the components and arrangements of specific examples are described below. Furthermore, the present invention may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. It should be noted that the components illustrated in the figures are not necessarily drawn to scale. Descriptions of well-known components and processing techniques and procedures are omitted so as to not unnecessarily limit the invention.

The following describes in detail a method for determining bearing capacity of a foundation to eliminate differences between different tests according to an embodiment of the present invention with reference to the accompanying drawings.

As shown in fig. 1, an embodiment of the present invention discloses a method for determining foundation bearing capacity to eliminate differences between different tests, where the method includes the following operations:

s1, determining the characteristic value of the bearing capacity of the foundation of each soil layer by using a flat shovel lateral expansion test;

s2, selecting static sounding test data, replacing the actual foundation bearing capacity value with the characteristic value of the foundation bearing capacity of the corresponding soil layer, and establishing the relation between the foundation bearing capacity and the specific penetration resistance by unitary linear regression;

s3, selecting standard penetration test data, replacing the actual foundation bearing capacity value with the characteristic value of the foundation bearing capacity of the corresponding soil layer, and establishing the relation between the foundation bearing capacity and the standard penetration hammering number by unitary linear regression;

s4, selecting indoor geotechnical test data, replacing the actual foundation bearing capacity value with the characteristic value of the foundation bearing capacity of the corresponding soil layer, and establishing the relation between the foundation bearing capacity and the porosity ratio and the liquidity index through multiple stepwise regression.

Because different test methods have different standards for judging soil damage, and some tests need to be corrected by probability statistics, the determined bearing force value has certain difference.

The embodiment of the invention establishes a relation formula by adopting a unitary linear regression method for the static penetration test and the standard penetration test and establishes a relation formula by adopting a multivariate stepwise regression method for the indoor geotechnical test based on the relation between the test data and the soil body, the test data of the static penetration test, the standard penetration test and the indoor geotechnical test and the characteristic value of the bearing capacity of the foundation determined by the flat shovel lateral expansion test.

The flat shovel lateral expansion test specifically comprises the steps of pressing a flat shovel measuring head connected to a probe rod into soil to a preset depth, applying air pressure to enable a round steel die located on one side face of the flat shovel measuring head to expand towards the soil, and measuring the pressure of three special positions (A, B, C) of the expansion of the steel die, so that various rock and soil parameters are obtained. Therefore, the characteristic value of foundation bearing capacity in the test area is obtained by utilizing the side expansion test result of the flat shovel.

The static sounding test specifically comprises the steps of pressing a static sounding head into foundation soil by using a hydraulic or mechanical transmission device, attaching a resistance strain gauge in the probe, when the probe is blocked, extending the resistance strain gauge to change the resistance, measuring a micro-strain value by using a resistance strain instrument, and calculating the magnitude of penetration resistance, thereby judging the engineering property of the foundation soil. And carrying out single-bridge static sounding in a test field region by using a static sounding method.

And drawing a Ps-h curve according to the recorded data, dividing the soil body into a plurality of soil layers with the same lithology according to the curve, obtaining a foundation bearing capacity value by utilizing a single-bridge static sounding obtained Ps value and a table look-up method.

And collecting the specific penetration resistance Ps value and the corresponding foundation bearing force value, replacing the foundation bearing force value with a foundation bearing force characteristic value obtained by a flat shovel side expansion test of a corresponding soil layer, and obtaining a relation formula between the foundation bearing force characteristic value and the specific penetration resistance of each soil layer by utilizing unitary linear regression.

For silt, the calculation formula is as follows:

σ_O＝0.031P_S+0.098

in the formula, σ_OIs the bearing force value (MPa) of the foundation, P_sSpecific penetration resistance (MPa);

for subsoil, the calculation formula is as follows:

σ_O＝0.0465P_S+0.0821

in the formula, σ_OIs the bearing force value (MPa) of the foundation, P_sSpecific penetration resistance (MPa);

for loam, the calculation is as follows:

σ_O＝0.051P_S+0.0648

in the formula, σ_OIs the bearing force value (MPa) of the foundation, P_sSpecific penetration resistance (MPa);

for clay, the calculation is as follows:

σ_O＝0.125P_S+0.016

in the formula, σ_OIs the bearing force value (MPa) of the foundation, P_sSpecific penetration resistance (MPa);

for mucky soil, the calculation formula is as follows:

σ_O＝0.116P_S+0.022

in the formula, σ_OIs the bearing force value (MPa) of the foundation, P_sThe specific penetration resistance (MPa).

The standard penetration test specifically comprises the steps of intermittently penetrating a cylindrical probe with certain mass at a drop distance of a certain length, judging engineering property parameters of foundation soil according to the hammering number of each shot with a certain length, and mechanically layering the foundation soil.

The test combines soil layers divided by a static cone penetration test curve, and corrects the field test hammering number N of each layer of soil, wherein the correction formula is as follows:

N＝μ-1.645σ

wherein mu is the average value of the hammering number of the field test, and sigma is the standard deviation of the hammering number of the field test.

And obtaining the foundation bearing force value by adopting a table look-up method for the clay and the sandy soil, and calculating the foundation bearing force value by utilizing the following formula for the silty soil:

σ_o＝22.7N+31.9

and collecting the standard penetration hammering number and the corresponding foundation bearing force value, replacing the foundation bearing force value with a characteristic value of the foundation bearing force obtained by the flat shovel side expansion test of the corresponding soil layer, and obtaining a relation formula between the foundation bearing force value and the standard penetration hammering number of each soil layer by utilizing unitary linear regression.

For silt, the calculation formula is as follows:

σ_O＝7.874N+51.34

in the formula, σ_OThe bearing capacity (kPa) of the foundation is taken as the standard penetration hammering number N;

for subsoil, the calculation formula is as follows:

σ_O＝10.232N+135.4

in the formula, σ_OThe bearing capacity (kPa) of the foundation is taken as the standard penetration hammering number N;

for loam, the calculation is as follows:

σ_O＝8.663N+110.98

in the formula, σ_OThe foundation bearing capacity (kPa) and N is the standard penetration hammering number.

The indoor soil test specifically comprises the steps of arranging a test field area near a drill hole, utilizing a thin-wall soil sampler, adopting a rapid static continuous pressing-in method, continuously sampling within a range of 3 meters below the ground surface, and carrying out a conventional soil test and a particle size test on a soil sample.

The test combines soil layers divided by a static penetration test curve to calculate the average value of the porosity ratio and the liquidity index of each soil layer, and the foundation bearing force value is determined by adopting the porosity ratio and the liquidity index.

And collecting the porosity ratio and the liquidity index and the corresponding foundation bearing capacity value, replacing the foundation bearing capacity value with a characteristic value of the foundation bearing capacity obtained by a flat shovel side expansion test of a corresponding soil layer, and obtaining a relational formula of the foundation bearing capacity value, the porosity ratio and the liquidity index of each soil layer by utilizing multiple stepwise regression.

For subsoil, the calculation formula is as follows:

σ_O＝-71.31e+83.59I_L+252.04

in the formula, σ_OIs foundation bearing capacity (kPa), e is porosity ratio, I_LIs a liquidity index;

for loam, the calculation is as follows:

σ_O＝-11.94e-59.72I_L+287.05

in the formula, σ_OIs foundation bearing capacity (kPa), e is porosity ratio, I_LIs a liquidity index.

According to the embodiment of the invention, the characteristic value of the foundation bearing capacity in the test area is obtained by using the flat shovel lateral expansion test, the characteristic value is taken as the basis, the parameters determined by the bearing capacity in the results of the static penetration test, the standard penetration test and the indoor geotechnical test are taken as variables, the relation formula is established by adopting a unitary linear regression method for the static penetration test and the standard penetration test, and the relation formula is established by adopting a multiple stepwise regression method for the indoor geotechnical test, so that the problem of large difference of the bearing capacity values obtained by different test methods is solved, the foundation bearing capacity in the test area can be determined quickly and accurately, the long-term and large-scale field observation and test are not needed, the labor input is reduced, and the cost is reduced.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.