CN115455712A - Soil compaction degree detection method based on response surface method - Google Patents

Soil compaction degree detection method based on response surface method Download PDF

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CN115455712A
CN115455712A CN202211152176.XA CN202211152176A CN115455712A CN 115455712 A CN115455712 A CN 115455712A CN 202211152176 A CN202211152176 A CN 202211152176A CN 115455712 A CN115455712 A CN 115455712A
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王柳江
臧耀辉
毛航宇
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Hohai University HHU
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Abstract

The invention relates to a soil compaction degree detection method based on a response surface method, which comprises the steps of firstly, taking a field test soil body to carry out an indoor calibration test, establishing a second-order response surface model of the change of the dielectric constant, the conductivity and the maximum penetration resistance of the soil body along with the change of mass water content and dry density, secondly, researching the correlation between the conductivity and the dielectric constant of the soil body, establishing a correction model of the conductivity of the soil body and calculating a conductivity correction value; then, substituting the actually measured dielectric constant, the actually measured maximum penetration resistance and the conductivity correction value into a second-order response curved surface model, and establishing an objective function according to the minimum root mean square error of the actually measured value and the calculated value; and finally, performing inversion by adopting a particle swarm optimization algorithm to obtain the mass water content and the dry density of the soil body, and calculating the soil body compaction degree.

Description

Soil compaction degree detection method based on response surface method
Technical Field
The invention relates to the technical field of rapid detection of water content and dry density of filled soil, in particular to a soil compaction degree detection method based on a response surface method.
Background
The soil material is widely applied in the field of infrastructure construction of water conservancy, traffic, municipal administration and the like, for example, the soil material is often used as a filling material of water retaining structures such as earth dams, core walls, dikes and the like in water conservancy engineering, the compactness is one of the most key indexes of construction management of filling engineering, and is directly related to the strength, deformation and stability of the filling engineering, wherein the mass water content and the dry density are two key parameters for determining the compactness, and the traditional detection method comprises the following steps: for the mass water content of the soil body, a drying method is adopted, and for the dry density of the soil body, a cutting ring method, a sand pouring method, a water pouring method and the like are generally adopted to be combined with the drying method for measurement; although the traditional detection methods have accurate and reliable test results, the traditional detection methods belong to destructive inspection, have the defects of few sampling points, low detection speed, high cost, large interference on construction and the like, and are difficult to meet the current rapid mechanized construction requirements; therefore, the engineering industry is always searching for a rapid testing method for the mass water content and the dry density of the soil body with rapidness, no damage and high precision so as to improve the detection efficiency of the soil body compaction degree.
At present, a method for rapidly and nondestructively detecting the soil compaction degree comprises a one-step detection method (Chen, chen Wei, chen Renpeng and the like) based on a time domain reflection Technology (TDR) or a frequency domain reflection technology (FDR). The TDR jointly monitors the design and application of a sensor of the water content and the dry density of the soil [ J ]. The report of rock mechanics and engineering 2011, 30 (2): 418-426). The method mainly carries out linear fitting on the dielectric constant, the conductivity, the water content and the dry density of the soil once, and further derives a calculation formula of the water content and the dry density.
Because the one-step detection method does not consider the secondary effect and the interaction effect of the water content and the dry density on the influence of the dielectric constant and the conductivity of the soil body, and the dielectric constant of the test value is difficult to comprehensively reflect the influence of the water content and the dry density, the precision of the measured mass water content and the dry density of the soil body is low, so that the method cannot be suitable for different engineering filling soil bodies, and the soil body compaction degree after field rolling is difficult to accurately evaluate, therefore, the method for detecting the soil body compaction degree based on the response surface method is provided.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a soil compaction degree detection method based on a response surface method.
In order to achieve the purpose, the invention adopts the following scheme:
a soil compaction degree detection method based on a response surface method comprises the following steps:
s1: taking part of on-site soil to perform an indoor calibration experiment, preparing samples with different water contents and dry densities, testing the dielectric constant and conductivity of the soil by using an FDR sensor, and testing the maximum penetration resistance of the soil by using a penetrometer;
s2: taking the dielectric constant, the conductivity and the maximum penetration resistance of the soil body as response targets, taking the water content and the dry density of the soil body as influence factors, and considering linear effect, secondary effect and interaction effect to establish a second-order response curved surface model of the dielectric constant, the conductivity and the maximum penetration resistance of the soil body changing along with the mass water content and the dry density;
s3: establishing a correction model of the soil body conductivity according to the correlation between the soil body conductivity and the dielectric constant;
s4: connecting an FDR sensor and an penetrometer with an electric counter-force lifting device to form a set of portable rapid detection device, controlling lifting through a motor, inserting probes of the FDR sensor and the penetrometer into a compacted soil body, respectively measuring an actually measured dielectric constant and an actually measured maximum penetration resistance of the compacted soil body, substituting the actually measured dielectric constant into a correction model of soil body conductivity, and calculating to obtain a conductivity correction value of the soil body;
s5: and substituting the actually measured dielectric constant, the conductivity correction value and the actually measured maximum penetration resistance into a corresponding second-order response curved surface model by using the actually measured values of the three target values and the root-mean-square error of the model calculation value as a target function, and performing inversion based on a particle swarm optimization algorithm to obtain an optimal group of calculation parameters, namely the mass water content and the dry density of the field compacted soil body.
As a preferable technical scheme:
in the method for detecting soil compaction degree based on the response surface method, in step S2, the second-order response surface model of the soil body, in which the dielectric constant, the conductivity and the maximum penetration resistance vary with the mass water content and the dry density, has the following expression:
Figure DEST_PATH_IMAGE002
in the formula (I), the compound is shown in the specification,
Figure DEST_PATH_IMAGE004
、
Figure DEST_PATH_IMAGE006
、
Figure DEST_PATH_IMAGE008
respectively is a response surface function of the dielectric constant, the conductivity and the maximum penetration resistance of the soil body;
Figure DEST_PATH_IMAGE010
、
Figure DEST_PATH_IMAGE012
、
Figure DEST_PATH_IMAGE014
in order to truncate the coefficients, the coefficients are,
Figure DEST_PATH_IMAGE016
、
Figure DEST_PATH_IMAGE018
、
Figure DEST_PATH_IMAGE020
、
Figure DEST_PATH_IMAGE022
、
Figure DEST_PATH_IMAGE024
、
Figure DEST_PATH_IMAGE026
is a coefficient of a linear term and is,
Figure DEST_PATH_IMAGE028
、
Figure DEST_PATH_IMAGE030
、
Figure DEST_PATH_IMAGE032
in order to be a coefficient of the interaction term,
Figure DEST_PATH_IMAGE034
、
Figure DEST_PATH_IMAGE036
、
Figure DEST_PATH_IMAGE038
、
Figure DEST_PATH_IMAGE040
、
Figure DEST_PATH_IMAGE042
、
Figure DEST_PATH_IMAGE044
the coefficients are parameters obtained after least square fitting and are determined by a calibration test;
Figure DEST_PATH_IMAGE046
the water content of the soil mass is the water content of the soil mass,
Figure DEST_PATH_IMAGE048
is the dry density.
In the method for detecting soil compaction degree based on the response surface method, the soil conductivity correction model in the step S3 adopts the following function:
Figure DEST_PATH_IMAGE050
in the formula (I), the compound is shown in the specification,
Figure DEST_PATH_IMAGE052
,
Figure DEST_PATH_IMAGE054
,
Figure DEST_PATH_IMAGE056
,
Figure DEST_PATH_IMAGE058
in order to be the parameters of the model,
Figure DEST_PATH_IMAGE060
in order to correct the value of the electrical conductivity,
Figure DEST_PATH_IMAGE062
is the dielectric constant.
In step S5, the measured dielectric constant, the corrected conductivity value, and the measured maximum penetration resistance are selected as known quantities, and an equal weight method is adopted to construct an objective function:
Figure DEST_PATH_IMAGE064
in the formula (I), the compound is shown in the specification,
Figure DEST_PATH_IMAGE066
in order to measure the dielectric constant of the dielectric material,
Figure DEST_PATH_IMAGE060A
in order to correct the value of the electrical conductivity,Pthe maximum penetration resistance is actually measured;
Figure DEST_PATH_IMAGE004A
、
Figure DEST_PATH_IMAGE006A
and
Figure DEST_PATH_IMAGE008A
is the dielectric constant of the earthAnd the response surface function corresponding to the electric conductivity and the maximum penetration resistance.
In the step S4, the FDR sensor and the penetrometer are detachably connected with the bottom of the dowel bar of the electric counterforce lifting device by a thread, and when in-situ detection is performed, the penetrometer is connected to measure the maximum penetration resistance, the FDR sensor is connected to measure the dielectric constant, and the numerical values are recorded in the acquisition instrument; during testing, the probe penetration speed is controlled by the motor;
the FDR sensor comprises a circuit board, an FDR sensor external thread column arranged above the circuit board, an FDR probe arranged below the circuit board and an FDR sensor data conducting wire connected with the circuit board; the penetrometer comprises a load sensor, a penetrometer external thread column arranged above the load sensor, a microprobe arranged below the load sensor, and a penetrometer data transmission line connected with the load sensor; electric reaction elevating gear includes the bottom plate and the backup pad parallel with the bottom plate, the both sides of bottom plate respectively are provided with a running-board, through 4 supporting screw fixed connection between bottom plate and the backup pad, set up the circular through-hole that can make FDR sensor and injection appearance pass in the middle of the bottom plate, the dowel steel is worn to be equipped with perpendicularly to the backup pad, set up the screw hole with FDR sensor external screw thread post and injection appearance external screw thread post adaptation in the inside axial of dowel steel, the one end that circular through-hole was kept away from to the dowel steel is provided with lift transmission, lift transmission fixes in the backup pad, and one side is provided with the motor, the motor is connected with the collection appearance through gathering appearance data transmission line, the motor is connected with the power.
The principle of the invention is as follows:
firstly, taking an on-site test soil body to carry out an indoor calibration test, researching the relation between the dielectric constant, the conductivity and the maximum penetration resistance of the soil body and the mass water content and the dry density, considering the linear effect, the quadratic effect and the interaction effect, establishing a second-order response curved surface model of the dielectric constant, the conductivity and the maximum penetration resistance of the soil body changing along with the mass water content and the dry density, determining corresponding model parameters through least square fitting, simultaneously researching the correlation between the conductivity and the dielectric constant of the soil body, and establishing a correction model of the conductivity of the soil body; secondly, the FDR sensor, the penetrometer and the electric reaction force lifting device are fixedly connected through threads to form a set of portable rapid detection equipment, the actually measured dielectric constant and the actually measured maximum penetration resistance of the on-site compacted soil body are tested, and the conductivity correction value is obtained through calculation by utilizing the actually measured dielectric constant; then, substituting the actually measured dielectric constant, the actually measured maximum penetration resistance and the conductivity correction value into a second-order response curved surface model, and establishing an objective function according to the minimum root mean square error of the actually measured value and the calculated value; and finally, performing inversion by adopting a particle swarm optimization algorithm to obtain the mass water content and the dry density of the soil body, and calculating the compaction degree of the soil body.
The invention provides a soil compaction degree detection method based on a response surface method, which has the following beneficial effects:
(1) Firstly, taking a field test soil body to carry out an indoor calibration test, researching the relation between the dielectric constant, the conductivity and the maximum penetration resistance of the soil body and the mass water content and the dry density, establishing a second-order response curved surface model of the change of the dielectric constant, the conductivity and the maximum penetration resistance of the soil body along with the mass water content and the dry density, and determining model parameters of response; meanwhile, the correlation between the soil body conductivity and the dielectric constant is researched, a correction model of the soil body conductivity is established, and the problem that the conductivity of the soil body pore water is inconsistent with that of an indoor calibration test in field detection is solved;
(2) Substituting the actually measured dielectric constant, the actually measured maximum penetration resistance and the conductivity correction value into a second-order response curved surface model, establishing a target function according to the minimum root mean square error of the actually measured value and the calculated value, performing inversion by adopting a particle swarm optimization algorithm to obtain the mass water content and the dry density of the soil body, and giving the compactness; the method is characterized in that the detection of the maximum penetration resistance is added on the basis of the original one-step method, the secondary effect and the interaction effect of the water content and the dry density on the influence of the dielectric constant, the conductivity and the maximum penetration resistance are considered, the established second-order response surface model can be basically applied to all types of soil bodies, and the precision of the predicted mass water content and dry density of the soil body is greatly improved;
(3) The actually measured dielectric constant and the actually measured maximum penetration resistance of the soil body can be quickly measured under the assistance of the electric counter-force lifting device, so that the detection efficiency of the compaction degree of the soil body can be effectively improved, and the practical contradiction between the filling construction quality detection and the quick mechanized construction is relieved;
(4) The method effectively overcomes the defects of few sampling points, low detection speed, high cost, large construction interference and the like in the traditional destructive detection method of the compaction degree; meanwhile, the problems of poor applicability and low testing precision of a one-step method based on dielectric constant and conductivity testing in different types of soil bodies are solved, and the soil body compaction degree detection efficiency and detection precision are greatly improved.
Drawings
FIG. 1 is a flow chart of a soil compaction degree detection method based on a response surface method according to the invention;
FIG. 2 is a schematic view of an electric reaction force elevating device according to the present invention;
FIG. 3 is a schematic view of an FDR sensor according to the invention;
FIG. 4 is a schematic view of a penetrometer according to the invention;
FIG. 5 is a graph of the dielectric constant response curve of the present invention;
FIG. 6 is a graph of a conductivity response curve of the present invention;
FIG. 7 is a graph of a penetration resistance response surface of the present invention;
in the figure: 2-1, a foot pedal; 2-2, a bottom plate; 2-3, supporting a screw rod; 2-4, a dowel bar; 2-5, a support plate; 2-6, a lifting transmission device; 2-7, a motor; 2-8, collecting instrument data conducting wires; 2-9, collecting instrument; 2-10 parts of internal threads; 3-1, FDR probe; 3-2, a circuit board; 3-3, an FDR sensor external threaded column; 3-4, FDR sensor data conducting wire; 3-5, a microprobe; 3-6, a load sensor; 3-7, penetrating the data conducting wire of the instrument; 3-8, and forming an external threaded column of the penetrometer.
Detailed Description
The present invention will be further described with reference to the following embodiments. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Further, it should be understood that various changes or modifications of the present invention can be made by those skilled in the art after reading the teaching of the present invention, and these equivalents also fall within the scope of the claims appended to the present application.
Example 1
A soil compaction degree detection method based on a response surface method is shown in figure 1 and comprises the following specific steps:
s1: taking part of on-site soil to perform an indoor calibration experiment, preparing samples with different water contents and dry densities, testing the dielectric constant and conductivity of the soil by using an FDR sensor, and testing the maximum penetration resistance of the soil by using a penetrometer;
s2: taking the dielectric constant, the conductivity and the maximum penetration resistance of the soil body as response targets, taking the water content and the dry density of the soil body as influence factors, and considering linear effect, secondary effect and interaction effect to establish a second-order response curved surface model of the dielectric constant, the conductivity and the maximum penetration resistance of the soil body changing along with the mass water content and the dry density;
the second-order response curved surface model of the soil body with the dielectric constant, the conductivity and the maximum penetration resistance changing along with the mass water content and the dry density has the following expression:
Figure DEST_PATH_IMAGE072
in the formula (I), the compound is shown in the specification,
Figure DEST_PATH_IMAGE004AA
、
Figure DEST_PATH_IMAGE006AA
、
Figure DEST_PATH_IMAGE008AA
respectively is a response surface function of the dielectric constant, the conductivity and the maximum penetration resistance of the soil body;
Figure DEST_PATH_IMAGE010A
、
Figure DEST_PATH_IMAGE012A
、
Figure DEST_PATH_IMAGE014A
in order to truncate the coefficients, the coefficients are,
Figure DEST_PATH_IMAGE016A
、
Figure DEST_PATH_IMAGE018A
、
Figure DEST_PATH_IMAGE020A
、
Figure DEST_PATH_IMAGE022A
、
Figure DEST_PATH_IMAGE024A
、
Figure DEST_PATH_IMAGE026A
is the coefficient of a linear term and is,
Figure DEST_PATH_IMAGE028A
、
Figure DEST_PATH_IMAGE030A
、
Figure DEST_PATH_IMAGE032A
in order to be a coefficient of the interaction term,
Figure DEST_PATH_IMAGE034A
、
Figure DEST_PATH_IMAGE036A
、
Figure DEST_PATH_IMAGE038A
、
Figure DEST_PATH_IMAGE040A
、
Figure DEST_PATH_IMAGE042A
、
Figure DEST_PATH_IMAGE044A
the coefficients are parameters obtained after least square fitting and are determined by a calibration test;
Figure DEST_PATH_IMAGE046A
the water content of the soil mass is the water content,
Figure DEST_PATH_IMAGE048A
is a dry density;
s3: establishing a correction model of the soil body conductivity according to the correlation between the soil body conductivity and the dielectric constant;
the soil body conductivity correction model adopts the following functions:
Figure DEST_PATH_IMAGE050A
in the formula (I), the compound is shown in the specification,
Figure DEST_PATH_IMAGE052A
,
Figure DEST_PATH_IMAGE054A
,
Figure DEST_PATH_IMAGE056A
,
Figure DEST_PATH_IMAGE058A
in order to be the parameters of the model,
Figure DEST_PATH_IMAGE060AA
in order to correct the value for the electrical conductivity,
Figure DEST_PATH_IMAGE062A
is the dielectric constant;
s4: connecting the FDR sensor and the penetrometer with an electric counter-force lifting device to form a set of portable rapid detection device, controlling lifting through a motor, inserting probes of the FDR sensor and the penetrometer into a compacted soil body, respectively measuring the dielectric constant and the maximum penetration resistance of the compacted soil body, substituting the dielectric constant into a conductivity correction model, and calculating to obtain a correction value of the conductivity of the soil body;
as shown in fig. 2, 3 and 4, the FDR sensor comprises a circuit board 3-2, an FDR sensor external thread column arranged above the circuit board 3-2, an FDR probe 3-1 arranged below the circuit board 3-2, and an FDR sensor data transmission line 3-4 connected with the circuit board 3-2; the penetrometer comprises a load sensor 3-6, a penetrometer external thread column 3-8 arranged above the load sensor 3-6, a microprobe 3-5 arranged below the load sensor 3-6, and a penetrometer data transmission line 3-7 connected with the load sensor 3-6; the electric counter-force lifting device comprises a bottom plate 2-2 and a supporting plate 2-5 parallel to the bottom plate 2-2, wherein two sides of the bottom plate are respectively provided with a pedal 2-1, the bottom plate 2-2 and the supporting plate 2-5 are fixedly connected through 4 supporting screws 2-3, a circular through hole through which an FDR sensor and a penetrometer can pass is formed in the middle of the bottom plate 2-2, a dowel bar 2-4 vertically penetrates through the supporting plate 2-5, a threaded hole 2-10 matched with an FDR sensor external threaded column 3-3 and a penetrometer external threaded column 3-8 is formed in the dowel bar 2-4 in the axial direction, one end, far away from the circular through hole, of the dowel bar 2-4 is provided with a lifting transmission device 2-6, the lifting transmission device 2-6 is fixed on the supporting plate 2-5, one side of the electric motor 2-7 is provided with an acquisition transmission device 2-9 through an acquisition device data line 2-8, and the electric motor 2-7 is connected with a power supply;
the FDR sensor and the penetrometer are connected with the electric counter-force lifting device, namely the FDR sensor and the penetrometer are detachably connected with the bottom of a dowel bar of the electric counter-force lifting device by screw threads, and when the FDR sensor and the penetrometer are detected on site, the FDR sensor is connected to measure the maximum penetration resistance, then the FDR sensor is connected to measure the dielectric constant, and the numerical values are recorded in the acquisition instrument; during testing, the penetration speed of the probe is controlled by the motor;
s5: substituting the actually measured dielectric constant, the conductivity correction value and the actually measured maximum penetration resistance into a corresponding second-order response curved surface model by using the actually measured values of the three target values and the root-mean-square error of the model calculation value as a target function, and performing inversion based on a particle swarm optimization algorithm to obtain an optimal group of calculation parameters, namely the mass water content and the dry density of the field compacted soil body;
the target function is constructed by adopting an equal weight method, and is as follows:
Figure DEST_PATH_IMAGE064A
in the formula (I), the compound is shown in the specification,
Figure DEST_PATH_IMAGE066A
in order to measure the dielectric constant of the dielectric material,
Figure DEST_PATH_IMAGE060AAA
in order to correct the value of the electrical conductivity,Pthe maximum penetration resistance is actually measured;
Figure DEST_PATH_IMAGE004AAA
、
Figure DEST_PATH_IMAGE006AAA
and
Figure DEST_PATH_IMAGE008AAA
the function is a response surface function corresponding to the dielectric constant, the conductivity and the maximum penetration resistance of the soil body.
Example 2
A soil compaction degree detection method based on a response surface method comprises the following specific steps:
step 1: drying the soil taken back on site, sieving with a 2mm sieve, mixing the sieved soil with tap water, preparing a soil sample with the mass water content of 14%,16%,18% and 20%, sealing for 72 hours, and placing in an organic glass barrel (diameter 100mm, height 150 mm) according to the target dry density (1.3 g/cm) 3 、1.4g/cm 3 、1.5g/cm 3 、1.6g/cm 3 ) Compacting into soil columns with different water contents and dry densities by five layers, and roughening the surface by using a cutter after each layer is compacted so as to reduce the layering phenomenon between the soil columns and the subsequent compacted layers;
step 2: after the soil column is prepared, firstly testing the maximum injection resistance of the soil body by using an injection instrument, then testing the dielectric constant and the conductivity of the soil body by using an FDR sensor, keeping the probe to be inserted at a constant speed during testing, changing the insertion position of the probe, repeating 3~5 times of measurement, and taking an average value;
the penetrometer comprises a load sensor and a miniature probe, the total length of the probe is 66mm, the probe is conical, the included angle is 60 degrees, the diameter of the upper end of the probe is 3.4mm, the diameter of the probe rod is 3.0mm, and the probe rod is slightly smaller than the probe, so that the friction between the probe rod and the side wall in the penetrometer during the penetrometer is eliminated; the FDR sensor comprises a main body and three probes, wherein the probes are 70mm in length, 3mm in diameter and 13mm in distance, the dielectric constant and the conductivity of a soil body can be measured simultaneously, and the test data of the probes and the conductivity of the soil body are recorded in an acquisition instrument;
and step 3: taking the dielectric constant, the conductivity and the maximum penetration resistance of the soil body as response targets, taking the water content and the dry density of the soil body as influence factors, and considering linear effect, secondary effect and interaction effect to establish a second-order response curved surface model of the dielectric constant, the conductivity and the maximum penetration resistance of the soil body changing along with the mass water content and the dry density:
Figure DEST_PATH_IMAGE072A
in the formula (I), the compound is shown in the specification,
Figure DEST_PATH_IMAGE004AAAA
、
Figure DEST_PATH_IMAGE006AAAA
、
Figure DEST_PATH_IMAGE008AAAA
respectively is a response surface function of the dielectric constant, the conductivity and the maximum penetration resistance of the soil body;
Figure DEST_PATH_IMAGE010AA
、
Figure DEST_PATH_IMAGE012AA
、
Figure DEST_PATH_IMAGE014AA
in order to truncate the coefficients, the coefficients are,
Figure DEST_PATH_IMAGE016AA
、
Figure DEST_PATH_IMAGE018AA
、
Figure DEST_PATH_IMAGE020AA
、
Figure DEST_PATH_IMAGE022AA
、
Figure DEST_PATH_IMAGE024AA
、
Figure DEST_PATH_IMAGE026AA
is the coefficient of a linear term and is,
Figure DEST_PATH_IMAGE028AA
、
Figure DEST_PATH_IMAGE030AA
、
Figure DEST_PATH_IMAGE032AA
in order to be a coefficient of the interaction term,
Figure DEST_PATH_IMAGE034AA
、
Figure DEST_PATH_IMAGE036AA
、
Figure DEST_PATH_IMAGE038AA
、
Figure DEST_PATH_IMAGE040AA
、
Figure DEST_PATH_IMAGE042AA
、
Figure DEST_PATH_IMAGE044AA
the coefficients are parameters obtained after least square fitting and are determined by a calibration test;
Figure DEST_PATH_IMAGE046AA
the water content of the soil mass is the water content,
Figure DEST_PATH_IMAGE048AA
the response curves of the dielectric constant, the conductivity and the maximum penetration resistance are shown in fig. 5, 6 and 7;
and 4, step 4: establishing a soil body conductivity correction model according to the correlation between the soil body conductivity and the dielectric constant:
Figure DEST_PATH_IMAGE050AA
in the formula (I), the compound is shown in the specification,
Figure DEST_PATH_IMAGE052AA
,
Figure DEST_PATH_IMAGE054AA
,
Figure DEST_PATH_IMAGE056AA
,
Figure DEST_PATH_IMAGE058AA
in order to be the parameters of the model,
Figure DEST_PATH_IMAGE060AAAA
in order to correct the value of the electrical conductivity,
Figure DEST_PATH_IMAGE062AA
is the dielectric constant;
and 5: connecting an FDR sensor and an penetrometer with an electric counter-force lifting device to form a set of portable rapid detection device, inserting probes of the FDR sensor and the penetrometer into a field compacted soil body through the lifting control of a motor, respectively measuring an actually measured dielectric constant and an actually measured maximum penetration resistance of the field compacted soil body, substituting the actually measured dielectric constant into an electric conductivity correction model, and calculating to obtain an electric conductivity correction value of the field compacted soil body;
wherein, FDR sensor and penetrometer adopt detachable threaded connection with electric reaction elevating gear's dowel steel bottom. During on-site test, firstly connecting a penetrometer to measure the maximum penetration resistance, then connecting an FDR sensor to measure the dielectric constant and the conductivity, recording numerical values in an acquisition instrument, and controlling the penetration speed of a probe through a motor during test;
step 6: taking the actually measured dielectric constant, the conductivity correction value and the actually measured maximum penetration resistance as known quantities, substituting the known quantities into a corresponding second-order response curved surface model, and constructing an objective function by adopting an equal weight method according to the principle that the root mean square error of the actually measured values and the calculated values of three target values is minimum:
Figure DEST_PATH_IMAGE064AA
in the formula (I), the compound is shown in the specification,
Figure DEST_PATH_IMAGE066AA
in order to measure the dielectric constant of the dielectric material,
Figure DEST_PATH_IMAGE060_5A
in order to correct the value for the electrical conductivity,Pthe maximum penetration resistance is actually measured;
Figure DEST_PATH_IMAGE004_5A
、
Figure DEST_PATH_IMAGE006_5A
and
Figure DEST_PATH_IMAGE008_5A
the method comprises the steps of obtaining a response surface function corresponding to the dielectric constant, the conductivity and the maximum penetration resistance of the soil body, and then carrying out inversion based on a particle swarm optimization algorithm to obtain an optimal set of calculation parameters, namely the mass water content and the dry density of the on-site compacted soil body;
wherein, in the steps 5 and 6: after the field data is acquired, cutting ring sampling can be carried out on the inserted position of the probe, the actual mass water content and the dry density of the soil body are measured by combining a cutting ring method and a drying method, and the mass water content and the dry density obtained by utilizing the inversion of the method provided by the invention can be compared with the mass water content and the dry density measured by combining the cutting ring method and the drying method;
the soil sample and the soil column are detected twice, the obtained measured value data are shown in tables 1 and 2, and the test results show that the soil compaction degree detection method based on the response surface method has more accurate test results on the soil compaction degree compared with the traditional ring cutter method and the drying method, and is suitable for different engineering filling soil bodies.
TABLE 1
Figure DEST_PATH_IMAGE145
TABLE 2
Figure DEST_PATH_IMAGE147

Claims (5)

1. A soil compaction degree detection method based on a response surface method is characterized by comprising the following steps:
s1: taking part of on-site soil to perform an indoor calibration experiment, preparing samples with different water contents and dry densities, testing the dielectric constant and conductivity of the soil by using an FDR sensor, and testing the maximum penetration resistance of the soil by using a penetrometer;
s2: taking the dielectric constant, the conductivity and the maximum penetration resistance of the soil body as response targets, taking the water content and the dry density of the soil body as influence factors, and considering linear effect, secondary effect and interaction effect to establish a second-order response curved surface model of the dielectric constant, the conductivity and the maximum penetration resistance of the soil body changing along with the mass water content and the dry density;
s3: establishing a correction model of the soil body conductivity according to the correlation between the soil body conductivity and the dielectric constant;
s4: connecting an FDR sensor and an penetrometer with an electric counter-force lifting device to form a set of portable rapid detection device, controlling lifting through a motor, inserting probes of the FDR sensor and the penetrometer into a compacted soil body, respectively measuring an actually measured dielectric constant and an actually measured maximum penetration resistance of the compacted soil body, substituting the actually measured dielectric constant into a correction model of soil body conductivity, and calculating to obtain a conductivity correction value of the soil body;
s5: and substituting the actually measured dielectric constant, the conductivity correction value and the actually measured maximum penetration resistance as known quantities into a corresponding second-order response surface model, taking the actually measured values of the three target values and the root-mean-square error of the model calculation value as a target function, and performing inversion based on a particle swarm optimization algorithm to obtain an optimal group of calculation parameters, namely the mass water content and the dry density of the on-site compacted soil body.
2. The method for detecting the soil compaction degree based on the response surface method as claimed in claim 1, wherein in the step S2, the second-order response surface model of the soil body with the dielectric constant, the conductivity and the maximum penetration resistance varying with the mass water content and the dry density has the following expression:
Figure 590893DEST_PATH_IMAGE002
in the formula (I), the compound is shown in the specification,
Figure 321083DEST_PATH_IMAGE004
、
Figure 163137DEST_PATH_IMAGE006
、
Figure 861141DEST_PATH_IMAGE008
respectively is a response surface function of the dielectric constant, the conductivity and the maximum penetration resistance of the soil body;
Figure 3410DEST_PATH_IMAGE010
、
Figure 107763DEST_PATH_IMAGE012
、
Figure 640376DEST_PATH_IMAGE014
to cut offThe coefficients of which are such that,
Figure 901593DEST_PATH_IMAGE016
、
Figure 350897DEST_PATH_IMAGE018
、
Figure 672157DEST_PATH_IMAGE020
、
Figure 692066DEST_PATH_IMAGE022
、
Figure 242127DEST_PATH_IMAGE024
、
Figure 296671DEST_PATH_IMAGE026
is the coefficient of a linear term and is,
Figure 41029DEST_PATH_IMAGE028
、
Figure 813813DEST_PATH_IMAGE030
、
Figure 620095DEST_PATH_IMAGE032
in order to be a coefficient of the interaction term,
Figure 342195DEST_PATH_IMAGE034
、
Figure 208520DEST_PATH_IMAGE036
、
Figure 999758DEST_PATH_IMAGE038
、
Figure 593419DEST_PATH_IMAGE040
、
Figure 419293DEST_PATH_IMAGE042
、
Figure 722098DEST_PATH_IMAGE044
the coefficients are quadratic coefficients, and all the coefficients are model least square fitting parameters and are determined by a calibration test fitting;
Figure 689048DEST_PATH_IMAGE046
the water content of the soil mass is the water content,
Figure 899450DEST_PATH_IMAGE048
is the dry density.
3. The soil compaction degree detection method based on the response surface method as claimed in claim 1, wherein the soil conductivity correction model in the step S3 adopts the following function:
Figure 783092DEST_PATH_IMAGE050
in the formula (I), the compound is shown in the specification,
Figure 40155DEST_PATH_IMAGE052
,
Figure 212510DEST_PATH_IMAGE054
,
Figure 961023DEST_PATH_IMAGE056
,
Figure 449904DEST_PATH_IMAGE058
are the parameters of the model and are used as the parameters,
Figure 891250DEST_PATH_IMAGE060
in order to correct the value of the electrical conductivity,
Figure 82060DEST_PATH_IMAGE062
is the dielectric constant.
4. The model for predicting soil dry compaction degree and the testing method thereof based on the response surface method as claimed in claim 1, wherein in step S5, the measured dielectric constant, the conductivity correction value and the measured maximum penetration resistance are selected as known quantities, and an equal weight method is adopted to construct an objective function:
Figure 352373DEST_PATH_IMAGE064
in the formula (I), the compound is shown in the specification,
Figure 679449DEST_PATH_IMAGE066
in order to measure the dielectric constant of the dielectric material,
Figure 494959DEST_PATH_IMAGE060
in order to correct the value of the electrical conductivity,Pthe maximum penetration resistance is actually measured;
Figure DEST_PATH_IMAGE067
、
Figure DEST_PATH_IMAGE068
and
Figure 48431DEST_PATH_IMAGE008
the response surface function is corresponding to the dielectric constant, the conductivity and the maximum penetration resistance of the soil body.
5. The soil compaction degree detection method based on the response surface method as claimed in claim 1, wherein in step S4, the FDR sensor and the penetrometer are detachably connected with the bottom of the dowel bar of the electric reaction force lifting device by a screw thread, and during field detection, the penetrometer is connected to measure the maximum penetration resistance, the FDR sensor is connected to measure the dielectric constant, and the numerical values are recorded in the acquisition instrument; during testing, the penetration speed of the probe is controlled by the motor.
CN202211152176.XA 2022-09-21 2022-09-21 Soil compaction degree detection method based on response surface method Pending CN115455712A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117074180A (en) * 2023-10-17 2023-11-17 天津风霖物联网科技有限公司 Method for measuring pressure change of underground soil body of building

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117074180A (en) * 2023-10-17 2023-11-17 天津风霖物联网科技有限公司 Method for measuring pressure change of underground soil body of building
CN117074180B (en) * 2023-10-17 2023-12-12 天津风霖物联网科技有限公司 Method for measuring pressure change of underground soil body of building

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