CN111323298A - Detection method of soil-based resilience modulus - Google Patents

Detection method of soil-based resilience modulus Download PDF

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Publication number
CN111323298A
CN111323298A CN201811523037.7A CN201811523037A CN111323298A CN 111323298 A CN111323298 A CN 111323298A CN 201811523037 A CN201811523037 A CN 201811523037A CN 111323298 A CN111323298 A CN 111323298A
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China
Prior art keywords
soil
loading
modulus
resilience
bearing plate
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CN201811523037.7A
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Inventor
徐春风
马骥
郑晶晶
孙艳
曹正保
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Jiangsu Tengda Engineering Testing Co ltd
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Jiangsu Tengda Engineering Testing Co ltd
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Priority to CN201811523037.7A priority Critical patent/CN111323298A/en
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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/08Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces

Abstract

The invention belongs to the technical field of pavement resilience modulus detection, and particularly relates to a method for detecting the resilience modulus of a soil foundation. Measuring the pressure-deformation curve of the soil base: pressurizing by using a pressurizing trolley, adopting a step-by-step loading and unloading method, controlling the loading capacity by using a heavy device, and increasing each step by 0.2kg when the load is less than 1kg and increasing each step by about 0.4kg later; in order to facilitate loading and calculation, the loaded numerical value can be properly adjusted to be an integer, the numerical values of the two deflection instrument dial indicators are read and recorded immediately, then the jack oil gate is slightly released to unload to 0, and the two deflection instrument dial indicators are read and recorded immediately and are not zero any more; finally, continuing the soil foundation resilience modulus according to a soil foundation resilience modulus calculation formula; it adopts adjustable counter weight device as the pressure device that soil matrix modulus of resilience detected, can observe soil matrix modulus of resilience change through the mode that promotes to roll, convenient and fast more.

Description

Detection method of soil-based resilience modulus
Technical Field
The invention belongs to the technical field of pavement resilience modulus detection, and particularly relates to a method for detecting the resilience modulus of a soil foundation.
Background
Combining the design specification requirement of a new round of road asphalt pavement, the parameters of the materials of each layer of the pavement are selected during the design of the road, namely, the rebound modulus value of each layer of the pavement is changed from the original static rebound modulus to the dynamic rebound modulus when the pavement structure is designed. For a roadbed, a dynamic triaxial test is required to obtain a dynamic resilience modulus value of roadbed soil, the existing instruments capable of performing the dynamic triaxial test comprise a dynamic triaxial apparatus and a large material testing machine (MTS and UTM), and the three test instruments have the common points of expensive equipment, complex operation and complex test flow. However, when the pavement structure is designed, a large number of soil samples need to be collected along the highway for testing, and the actual measurement method is not easy to realize for obtaining the modulus of resilience parameters of the roadbed, namely the actual measurement method cannot be completely adopted for obtaining the modulus of resilience parameters in the actual engineering design.
Various methods are available for estimating the resilience modulus of the roadbed at home and abroad, and the estimation method of the constitutive model can be divided into 3 types according to the difference of selected stress variables: models that consider only shear effects, models that consider only side-limiting effects, and composite models that consider both effects together. The shearing type model comprises a bilinear model and a hyperbolic model; the side limit type model comprises a confining pressure model and a K-theta model; the composite models comprise an Uzan model, a Tam-Brown model, an octahedral shear stress model and a Superpave performance model. The physical property index-based estimation methods include a USDA formula, a Missippi model 1, a Kim model and a Missippi model 2.
On the basis of deep analysis of main influence factors (soil group type, water content, compactness, stress condition and the like) of the resilience modulus, domestic and foreign scholars and research institutions establish corresponding resilience modulus estimation models from different angles such as the stress condition of roadbed soil, basic physical properties and indexes of the soil group and the like. The structural model establishes a functional relation between the modulus of resilience and the stress state from the perspective of the stress-strain relation, so that the structural model has universality, and the main defect is that only the influence of body stress or shear stress on the modulus of resilience of the material is considered. In fact, the modulus of most soils and aggregates increases with increasing confining pressure and decreases with increasing shear stress, i.e. the modulus of resilience is a function not only of the bulk stress but also of the shear or bias stress. The estimation model based on physical indexes considers the influence of soil group factors, but the rebound modulus value is not only related to the stress level, but also closely related to the soil group physical parameters.
Comprehensive analysis shows that although some achievements and a lot of beneficial experiences are obtained in the estimation of the resilience modulus parameter of the roadbed soil at home and abroad, the use of the empirical relations has limitations, the similarity between the use condition and the formula establishment condition needs to be investigated during use, the operation is not easy, the applicability is poor, and the resilience modulus value cannot be accurately estimated.
Disclosure of Invention
The invention aims to provide a method for detecting the resilience modulus of the soil foundation, which has the advantages of simple structure, reasonable design and convenient use, and aims to overcome the defects and defects of the prior art.
In order to achieve the purpose, the invention adopts the technical scheme that: the detection method comprises the following steps:
the method comprises the following steps: preparation work
1. Representative stations are selected as desired. The measuring points are positioned on the horizontal roadbed, the soil quality is uniform, and impurities are not contained;
2. carefully leveling the surface of the soil foundation, spreading dry and clean fine sand and soil to fill up the concave-convex parts of the soil foundation, wherein the sand can not cover the whole surface of the soil foundation, so as to avoid forming an interlayer;
3. arranging a bearing plate, and correcting by using a horizontal ruler to enable the bearing plate to be in a horizontal state;
4. mounting prefabricated rails on the left and right sides of the bearing plate, and keeping the prefabricated rail bearing plate horizontal and fixing;
5. placing a pressure applying trolley on the prefabricated track, and ensuring that the middle of the pressure applying trolley is consistent with the center of the bearing plate; in addition, the configuration blocks on the pressure applying trolley are kept symmetrical;
step two: method of operation
1. Starting loading by using a pressure applying trolley to enable the pre-pressing to reach 10 kg; stabilizing the pressure for 1min to make the bearing plate closely contact with the soil foundation, checking the electronic dial indicator to ensure that the working condition is normal, removing the pressure applying trolley, and after stabilizing the pressure for 1min, aligning the pointer to zero or recording the initial reading.
2. Measuring the pressure-deformation curve of the soil base: pressurizing by using a pressurizing trolley, adopting a step-by-step loading and unloading method, controlling the loading capacity by using a heavy device, and increasing each step by 0.2kg when the load is less than 1kg and increasing each step by about 0.4kg later; for loading and calculation convenience, the loaded value can be adjusted to an integer as appropriate. After the load is loaded to the preset load each time, stabilizing for 1min, immediately reading and recording the numerical values of two deflection instruments dial indicators, and then slightly releasing the jack oil gate to unload to 0; and immediately reading and recording the two deflection instrument dial indicators not to be zero after the unloading is stable for 1 min. And when the difference between the readings of the two benders does not exceed 30% of the average value, taking the average value, and if the average value exceeds 30%, re-measuring. When the rebound deformation value exceeds 1mm, the loading can be stopped.
Step three: the rebound deformation and the total deformation of each stage of load are calculated according to the following method:
rebound deflection L (average of readings after load-average of readings after load) × deflectometer lever ratio
And (4) measuring the total influence quantity a by using the lever ratio of the × deflectometer (the average value of the loading readings-the average value of the readings before the initial loading), taking away the jack after the last loading and unloading cycle is finished, re-reading the initial readings of the dial indicators, then opening the automobile for 10m away, and reading the final readings, wherein the average value of the differences between the initial readings and the final readings of the two dial indicators is the total influence quantity α.
Samples were taken at the test point and the water content of the material was determined. The number of samples was as follows:
① maximum grain size is not more than 4.75mm, sample number is about 120 g;
② maximum grain size is not more than 19.0mm, sample number is about 250 g;
③ maximum grain size is not more than 31.5mm, sample number is about 500 g;
the density of the soil base is measured by sand-pouring or ring-cutting method at a proper position near the test point.
The values of the method can be recorded and recorded on a recording table.
Preferably, the bearing plate has a square structure of 1 × 1 m.
Preferably, the width of the pressure applying trolley does not exceed half of the side length of the bearing plate.
Preferably, the dial indicator at the top end of the deflectometer is an electronic dial indicator, and the change curve of the dial indicator can be recorded in real time.
After adopting the structure, the invention has the beneficial effects that: it adopts adjustable counter weight device as the pressure device that soil matrix modulus of resilience detected, can observe soil matrix modulus of resilience change through the mode that promotes to roll, convenient and fast more.
Detailed Description
The present invention is further illustrated.
The specific implementation mode adopts the following technical scheme: the detection method comprises the following steps:
first, the method requires the following instruments and materials:
1) loading facilities: the truck is used as loading equipment, and the truck is loaded with heavy objects such as iron blocks or aggregates and the like, and the rear axle weight of the truck is not less than 60 kN. A stiffening cross beam is attached about 80cm behind the rear axle of the automotive frame, and serves as a reaction frame.
2) The field test device comprises: the device consists of a jack, a dynamometer (a force measuring ring or a pressure gauge) and a ball seat.
3) The rigid bearing plate is one, the plate thickness is 20mm, the diameter is phi 30cm, stand columns and supports capable of adjusting the height are arranged at two ends of the diameter and used for a security and protection deflectometer side head, and the bearing plate is placed on the surface of a soil foundation.
4) Two pavement benkelman beams, a dial indicator and a frame thereof.
5) And one hydraulic jack is provided with a calibrated pressure gauge or force measuring ring at 80-100 kN, the capacity of the pressure gauge or force measuring ring is not less than the soil foundation strength, and the measurement precision is not less than 1% of the measuring range of the dynamometer.
6) A stopwatch;
7) a level bar;
8) and others: fine sand, hairbrush, drooping ball, pickaxe, kalopanax septemlobus, shovel and the like.
Secondly, the detection method comprises the following steps:
the method comprises the following steps: preparation work
1. Representative stations are selected as desired. The measuring points are positioned on the horizontal roadbed, the soil quality is uniform, and impurities are not contained;
2. carefully leveling the surface of the soil foundation, spreading dry and clean fine sand and soil to fill up the concave-convex parts of the soil foundation, wherein the sand can not cover the whole surface of the soil foundation, so as to avoid forming an interlayer;
3. arranging a bearing plate, and correcting by using a horizontal ruler to enable the bearing plate to be in a horizontal state;
4. mounting prefabricated rails on the left and right sides of the bearing plate, and keeping the prefabricated rail bearing plate horizontal and fixing;
5. placing a pressure applying trolley on the prefabricated track, and ensuring that the middle of the pressure applying trolley is consistent with the center of the bearing plate; in addition, the configuration blocks on the pressure applying trolley are kept symmetrical;
step two: method of operation
1. Starting loading by using a pressure applying trolley to enable the pre-pressing to reach 10 kg; stabilizing the pressure for 1min to make the bearing plate closely contact with the soil foundation, checking the electronic dial indicator to ensure that the working condition is normal, removing the pressure applying trolley, and after stabilizing the pressure for 1min, aligning the pointer to zero or recording the initial reading.
2. Measuring the pressure-deformation curve of the soil base: pressurizing by using a pressurizing trolley, adopting a step-by-step loading and unloading method, controlling the loading capacity by using a heavy device, and increasing each step by 0.2kg when the load is less than 1kg and increasing each step by about 0.4kg later; for loading and calculation convenience, the loaded value can be adjusted to an integer as appropriate. After the load is loaded to the preset load each time, stabilizing for 1min, immediately reading and recording the numerical values of two deflection instruments dial indicators, and then slightly releasing the jack oil gate to unload to 0; and immediately reading and recording the two deflection instrument dial indicators not to be zero after the unloading is stable for 1 min. And when the difference between the readings of the two benders does not exceed 30% of the average value, taking the average value, and if the average value exceeds 30%, re-measuring. When the rebound deformation value exceeds 1mm, the loading can be stopped.
Step three: the rebound deformation and the total deformation of each stage of load are calculated according to the following method:
rebound deflection L (average of readings after load-average of readings after load) × deflectometer lever ratio
And (4) measuring the total influence quantity a by using the lever ratio of the × deflectometer (the average value of the loading readings-the average value of the readings before the initial loading), taking away the jack after the last loading and unloading cycle is finished, re-reading the initial readings of the dial indicators, then opening the automobile for 10m away, and reading the final readings, wherein the average value of the differences between the initial readings and the final readings of the two dial indicators is the total influence quantity α.
Samples were taken at the test point and the water content of the material was determined. The number of samples was as follows:
① maximum grain size is not more than 4.75mm, sample number is about 120 g;
② maximum grain size is not more than 19.0mm, sample number is about 250 g;
③ maximum grain size is not more than 31.5mm, sample number is about 500 g;
measuring the water content of the graph by using a drying method;
measuring the density of the soil foundation at a proper position close to the test point by using a sand-pouring method or a cutting ring method and the like;
the values of the method can be recorded and recorded on a recording table.
Third, calculate and summarize
1. Calculating the rebound deformation value which is the rebound deformation value of each pressure and the influence quantity of each stage
And (4) after the influence quantity of each stage is added to the rebound deformation value of each stage of pressure, calculating the rebound deformation value. And taking a standard vehicle with the rear axle weight of 60kN as a calculated value of each level of load influence quantity of the test vehicle. When using other types of test cars, the effect ai at each stage pressure is calculated:
ai=(T1+T2)πD2P1*a/4T1Q
in the formula: t is1-test carriage wheelbase (m);
T2-distance (m) of stiffening corbels from rear axle;
d, the diameter (m) of the bearing plate;
q-testing the rear axle weight (N) of the vehicle;
P1-the carrier plate pressure (Pa);
a-total impact (0.01 mm);
ai-the amount of the grading impact of the pressure in this stage (0.01 mm).
2. Formula for calculating soil-based resilience modulus
E0=πD(1—μ02)Σpi/4ΣLi
In the formula: e0-modulus of resilience of soil base (MPa);
mu 0, the Poisson's ratio of the soil, selected according to the ministerial road surface design specification;
li-actually measured rebound deformation values of all levels before ending the test;
pi-pressure values corresponding to the stages of Li.
After adopting the structure, the invention has the beneficial effects that: it adopts adjustable counter weight device as the pressure device that soil matrix modulus of resilience detected, can observe soil matrix modulus of resilience change through the mode that promotes to roll, convenient and fast more.
The working principle of the specific embodiment is as follows:
the above description is only for the purpose of illustrating the technical solutions of the present invention and not for the purpose of limiting the same, and other modifications or equivalent substitutions made by the person skilled in the art to the technical solutions of the present invention should be covered by the scope of the claims of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims (4)

1. The detection method of the soil-based resilience modulus is characterized by comprising the following steps: the detection method comprises the following steps:
the method comprises the following steps: preparation work
(1) Selecting representative measuring points according to needs; the measuring points are positioned on the horizontal roadbed, the soil quality is uniform, and impurities are not contained;
(2) carefully leveling the surface of the soil foundation, spreading dry and clean fine sand and soil to fill up the concave-convex parts of the soil foundation, wherein the sand can not cover the whole surface of the soil foundation, so as to avoid forming an interlayer;
(3) arranging a bearing plate, and correcting by using a horizontal ruler to enable the bearing plate to be in a horizontal state;
(4) the prefabricated rails are arranged on the left and the right of the bearing plate, and the prefabricated rail bearing plate is kept horizontal and fixed;
(5) placing a pressure applying trolley on the prefabricated track, and ensuring that the middle of the pressure applying trolley is consistent with the center of the bearing plate; in addition, the configuration blocks on the pressure applying trolley are kept symmetrical;
step two: method of operation
(1) Starting loading by using a pressure applying trolley to enable the pre-pressing to reach 10 kg; stabilizing the pressure for 1min to ensure that the bearing plate is in close contact with the soil foundation, checking an electronic dial indicator at the same time, ensuring that the working condition is normal, removing the pressure applying trolley, and after stabilizing the pressure for 1min, aligning a pointer to zero or recording an initial reading;
(2) and measuring the pressure-deformation curve of the soil foundation: pressurizing by using a pressurizing trolley, adopting a step-by-step loading and unloading method, controlling the loading capacity by using a heavy device, and increasing each step by 0.2kg when the load is less than 1kg and increasing each step by about 0.4kg later; in order to facilitate loading and calculation, the loaded numerical value can be properly adjusted to be an integer; after the load is loaded to the preset load each time, stabilizing for 1min, immediately reading and recording the numerical values of two deflection instruments dial indicators, and then slightly releasing the jack oil gate to unload to 0; when unloading is stable for 1min, immediately reading and recording that the two deflection instrument dial indicators are not zero any more; when the difference between the readings of the two deflection meters does not exceed 30% of the average value, taking the average value, and if the difference exceeds 30%, re-measuring; when the rebound deformation value exceeds 1mm, the loading can be stopped;
step three: the rebound deformation and the total deformation of each stage of load are calculated according to the following method:
rebound deflection L = (average of readings after loading-average of readings after unloading) × deflectometer lever ratio
The total deformation L' = (loading reading average value-loading initial reading average value) × deflectometer lever ratio measures total influence a, after the last loading and unloading cycle is finished, the jack is taken away, the initial reading of the dial indicator is read again, then the automobile is driven out of 10m, the final reading is read, the average value of the difference between the initial reading and the final reading of the two dial indicators is the total influence α;
sampling at a test point, and measuring the water content of the material; the number of samples was as follows:
① maximum grain size is not more than 4.75mm, sample number is about 120 g;
② maximum grain size is not more than 19.0mm, sample number is about 250 g;
③ maximum grain size is not more than 31.5mm, sample number is about 500 g;
measuring the density of the soil foundation at a proper position close to the test point by using a sand-pouring method or a cutting ring method and the like;
the values of the method can be recorded and recorded on a recording table.
2. The method for detecting the soil-based modulus of resilience according to claim 1, wherein: the bearing plate is of a 1 × 1m square structure.
3. The method for detecting the soil-based modulus of resilience according to claim 1, wherein: the width of the pressure applying trolley does not exceed half of the side length of the bearing plate.
4. The method for detecting the soil-based modulus of resilience according to claim 1, wherein: the dial indicator at the top end of the deflectometer is an electronic dial indicator, and the change curve of the dial indicator can be recorded in real time.
CN201811523037.7A 2018-12-13 2018-12-13 Detection method of soil-based resilience modulus Pending CN111323298A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113376020A (en) * 2021-06-29 2021-09-10 神龙汽车有限公司 Method for quantitatively detecting deformation resistance of cylinder cover bolt column

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Publication number Priority date Publication date Assignee Title
CN204626214U (en) * 2015-03-17 2015-09-09 广东华路交通科技有限公司 A kind of Benkleman beam deflectometer data collecting system

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Publication number Priority date Publication date Assignee Title
CN204626214U (en) * 2015-03-17 2015-09-09 广东华路交通科技有限公司 A kind of Benkleman beam deflectometer data collecting system

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Title
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Publication number Priority date Publication date Assignee Title
CN113376020A (en) * 2021-06-29 2021-09-10 神龙汽车有限公司 Method for quantitatively detecting deformation resistance of cylinder cover bolt column

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