An intelligent compaction method for subgrade considering temporal and spatial evolution of water content of fill

Abstract

The application discloses a kind of intelligent compaction method of subgrade considering the temporal and spatial evolution of filler moisture content, first collect the data required for field compaction, then successively establish wheel-road coupling model, compaction quality control index S and the functional relationship between compaction quality control index S and compaction degree K;Again, the compaction site is divided into three levels, finally according to the three-level area, draw compaction degree temporal and spatial distribution nephogram;Again, the compaction degree temporal and spatial distribution nephogram is comprehensively evaluated by subgrade full working face compaction quality evaluation method, when the compaction quality of all first-level areas meets the compaction requirement, subgrade full working face compaction quality evaluation is qualified, and compaction is completed.The application can continuously, non-destructively and real-time detect the temporal and spatial moisture content of subgrade filler, realize accurate and efficient detection of subgrade compaction quality, intuitively understand the real-time compaction state of subgrade and effectively guide construction, and improve the compaction quality and efficiency of subgrade filler.

Description

Technical Field

[0001] This invention belongs to the field of roadbed compaction quality control, specifically a roadbed intelligent compaction method that considers the spatiotemporal evolution of filler moisture content. Background Technology

[0002] The subgrade is the primary bearer of static loads and dynamic loads from vehicles on the overlying pavement structure, and is a crucial component for ensuring driving safety. The performance of the subgrade depends on the quality of the subgrade fill material and the compaction effect. The former can be controlled through the selection of fill material, while the latter requires compaction technology and quality control measures.

[0003] In the process of subgrade compaction, the moisture content of the fill material is a crucial indicator, directly affecting the compaction effect and quality. Therefore, real-time acquisition of the moisture content of the fill material during subgrade compaction is essential. Existing methods for detecting the moisture content of subgrade fill material mainly include the drying method, neutron method, tensiometer method, electrical method, resistance method, and time-domain reflectometry. The drying method is a traditional method for detecting moisture content; it is simple to operate, provides intuitive data, and has high measurement accuracy, but the measurement time is long. The neutron method involves placing a radioactive source in the soil and then detecting it with a slow neutron detector to obtain the moisture content of the fill material. Although this method can accurately measure the moisture state of the fill material, it is rarely used now due to its radioactive hazards. The tensiometer method measures the moisture content by measuring the suction force in the soil; however, the tensiometer method and the electrical method are difficult to obtain reliable moisture content results due to the anisotropy and complexity of the fill material. The resistance method involves inserting electrodes into the soil and measuring the resistivity of the soil between the two electrodes to obtain the moisture state of the soil. Time-domain reflectometry is a method for determining soil moisture content by utilizing the difference in the propagation speed of electromagnetic waves in different media.

[0004] Monitoring the moisture content of fill material during subgrade compaction primarily relies on point measurement. Representative measuring points are selected within the compacted subgrade area for moisture content testing, but the testing depth is mainly concentrated on the surface layer of newly compacted soil. This makes it difficult to continuously reflect the moisture content distribution of deeper fill material along the compaction path. Furthermore, the moisture content of the underlying fill material beneath the newly compacted subgrade layer also affects its compaction effect. Existing subgrade compaction methods lack intelligent and continuous monitoring of fill material moisture content and methods for determining the moisture content distribution of subgrade fill material within the compaction depth influenced by the roller. Current compaction degree detection technologies struggle to obtain fill material moisture content continuously in real time, and therefore cannot determine the subgrade compaction degree in real time by analyzing the relationship between moisture content and fill material density, thus providing the possibility for real-time intelligent adjustment of subgrade compaction construction parameters. In addition, most existing dynamic response equations for rollers and subgrades only consider the force balance between the two, neglecting the impact of fill material moisture content on its resilient modulus and its influence on compaction effect, and lack corresponding compaction quality control indicators. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the technical problem this invention aims to solve is to provide an intelligent compaction method for roadbeds that considers the spatiotemporal evolution of the moisture content of fillers.

[0006] The technical solution of this invention to solve the aforementioned technical problem is to provide a smart compaction method for roadbed that considers the spatiotemporal evolution of the moisture content of filler, characterized in that the method includes the following steps:

[0007] Step 1: Collect the data required for on-site compaction, including construction process parameter data, subgrade fill material parameter data, subgrade fill material volumetric moisture content data, and roller travel path data;

[0008] Step 2: Considering the influence of the spatiotemporal evolution of the volumetric moisture content w, a wheel-road coupling model is established by coupling the dynamic response equation of the subgrade fill material with the vibration force equation of the vibrating wheel, and simultaneously solving the volumetric moisture content equation, i.e., the vertical displacement solution u of the subgrade fill material. z Then, the vertical displacement u of the roadbed fill material is calculated. z By performing a second derivative, we obtain the solution α for the vertical acceleration of the subgrade fill material. z Next, the volumetric moisture content data of the subgrade fill material collected in step 1 is input into the wheel-road coupling model to obtain the vertical acceleration solution α of the subgrade fill material. z The maximum value α in each cycle max By combining the vibration acceleration α1 of the vibratory wheel, a compaction quality control index S is established, and the compaction quality control index S data is obtained. Then, the measured compaction quality control index S data and compaction degree K data are fitted to establish a functional relationship between compaction quality control index S and compaction degree K, and the compaction degree K data is obtained.

[0009] Step 3: Divide the compacted site into several primary zones, then divide each primary zone into several secondary zones, and finally divide each secondary zone into several tertiary zones.

[0010] Step 4: Based on the three-level regions divided in Step 3, plot the compaction degree K data obtained in Step 2 into a spatiotemporal distribution cloud map of compaction degree; then, comprehensively evaluate the spatiotemporal distribution cloud map of compaction degree using the subgrade full-face compaction quality evaluation method: if there are areas where the compaction quality does not meet the standards, adjust the roller construction process parameters and check whether there are any uncertain factors affecting the compaction effect in that area and deal with them immediately; when the compaction quality of all first-level regions meets the compaction requirements, the subgrade full-face compaction quality evaluation is qualified, and compaction is completed.

[0011] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0012] (1) This invention proposes a novel ground-penetrating radar mounting device for road rollers. The concave design ensures that it can be adapted to most road roller models and is simple to operate and easy to mount. By continuously, non-destructively, and in real time detecting the spatial and temporal moisture content of roadbed fill material through the built-in ground-penetrating radar, it provides a reliable moisture content data acquisition device for intelligent compaction methods.

[0013] (2) This invention proposes a wheel-road coupling model that considers moisture content. A wheel-road coupling model that considers the contact width between the vibrating wheel and the roadbed fill and the influence of moisture content is established. This model can obtain the vibration displacement and vibration acceleration data of the roadbed fill in real time and accurately, making the calculation results of the compaction quality control index more accurate and reliable.

[0014] (3) Based on the dynamic response of the vibrating wheel to the roadbed fill, the present invention proposes a new compaction quality control index. Through field tests, a functional relationship between the compaction quality control index and the degree of compaction is established, which can intuitively judge the quality of the roadbed fill compaction and provide effective guidance for subsequent compaction.

[0015] (4) This invention proposes a three-level zone division method for roadbed fill. Compared with traditional compaction quality control methods that only detect the surface, this invention considers the spatial range changes in the spatiotemporal evolution characteristics. By using the three-level zone division method, a spatiotemporal distribution cloud map of moisture content is obtained, providing more comprehensive and scientific guidance for subsequent roadbed compaction.

[0016] (5) This invention proposes a method for evaluating the compaction quality of the entire working face of the subgrade, which takes into account the changes in moisture content and compaction degree within the spatial range, as well as their influence on the compaction degree of the subgrade fill material. This method enables accurate and efficient detection of subgrade compaction quality, provides an intuitive understanding of the real-time compaction status of the subgrade and effectively guides construction, avoids the limitations of traditional compaction methods in terms of time discontinuity and space, and improves the compaction quality and efficiency of subgrade fill material. Attached Figure Description

[0017] Figure 1 This is an overall flowchart of the present invention;

[0018] Figure 2 This is a schematic diagram of the overall structure of the ground-penetrating radar mounting device of the present invention;

[0019] Figure 3 This is a schematic diagram showing the position and working principle of the ground-penetrating radar mounting device of the present invention mounted on a road roller;

[0020] Figure 4 This is a grid diagram of the travel path of the road roller according to the present invention;

[0021] Figure 5 This is a schematic diagram of the first-level region numbered 0001 according to an embodiment of the present invention.

[0022] In the diagram, 1 is the power switch, 2 is the working status indicator, 3 is the automatic telescopic baffle, 4 is the frequency signal display, 5 is the rod fixing screw, 6 is the ground penetrating radar, 7 is the shock absorption spring, 8 is the housing of the mounting device, 9 is the connecting rod, 10 is the global positioning satellite, 11 is the vehicle-mounted satellite signal receiver, and 12 is the ground penetrating radar mounting device. Detailed Implementation

[0023] Specific embodiments of the present invention are given below. These specific embodiments are only used to further illustrate the present invention in detail and do not limit the scope of protection of the present invention.

[0024] This invention provides a smart compaction method for roadbed considering the spatiotemporal evolution of filler moisture content (hereinafter referred to as the method), characterized by comprising the following steps:

[0025] Step 1: Collect the data required for on-site compaction, including construction process parameter data, subgrade fill material parameter data, subgrade fill material volumetric moisture content data, and roller travel path data;

[0026] In step 1, the construction process parameters include the frame mass m1, the vibratory wheel mass M0, the vibratory wheel length a, the Poisson's ratio v1 of the vibratory wheel material, the Young's modulus E1 of the vibratory wheel material, the vibratory wheel excitation frequency f, and the vibratory wheel nominal amplitude A0; the roadbed fill parameter data includes the roadbed fill material's Poisson's ratio v2.

[0027] In step 1, the method for collecting the volumetric moisture content data of the subgrade fill material is as follows: the ground-penetrating radar mounted device 12 is installed on the bottom of the road roller (in this embodiment, a heavy-duty single-drum road roller); during the road roller's movement within the compaction site, the ground-penetrating radar mounted device 12 continuously emits and receives electromagnetic waves and analyzes the electromagnetic wave signals, measures the propagation time of the electromagnetic wave signals within the compaction path in real time, obtains the dielectric constant ε of the subgrade fill material through the dielectric constant calculation method, and then converts the dielectric constant ε into volumetric moisture content data through the dielectric constant-volume moisture content function relationship of the subgrade fill material.

[0028] Preferably, in step 1, the ground-penetrating radar mounting device 12 (such as...) Figure 2 (As shown) includes a power switch 1, a working status indicator light 2, an automatic telescopic baffle 3, a frequency signal display 4, a ground-penetrating radar 6, a shock-absorbing spring 7, a mounting device housing 8, and a connecting rod 9;

[0029] Linkage 9 is slidably mounted on the housing 8 of the mounting device and fixed by rod fixing screws 5; the housing 8 of the mounting device is mounted on the bottom of the road roller via link 9; power switch 1, working status indicator 2 and frequency signal display 4 are mounted on the housing 8 of the mounting device; ground penetrating radar 6 is mounted inside the housing 8 of the mounting device via shock-absorbing spring 7, which is used to ensure the stability of the ground penetrating radar 6 during operation; the ground penetrating radar 6 is equipped with an electromagnetic wave signal transmitter and receiver, the transmitter is used to transmit electromagnetic waves into the ground, and the receiver is used to receive the reflected electromagnetic wave signals; automatic telescopic baffle 3 is slidably mounted on the bottom of the housing 8 of the mounting device, located at the ground penetrating radar 6; when the device is working, the automatic telescopic baffle 3 retracts, exposing the ground penetrating radar 6, facing the ground, and starting to work; when the device is closed, the automatic telescopic baffle 3 extends, cooperating with the housing 8 of the mounting device to enclose the ground penetrating radar 6 inside the housing 8 of the mounting device, protecting the ground penetrating radar 6;

[0030] Preferably, the power switch 1 is a control button used to control the start and stop of the ground penetrating radar mounted device 12; the working status indicator light 2 includes three lights: red, yellow and green. Red indicates that the device is not working, yellow indicates that it is in standby mode, and green indicates that it is in working mode; the frequency signal display 4 is an LED display screen used to display the collected volumetric water content information, which can be controlled by the control buttons on the display screen.

[0031] Preferably, the ground-penetrating radar 6 is equipped with an antenna with a frequency of 270-600MHz, which can detect depths of 2-5m. During detection, different frequencies are selected based on the depth of the roadbed filling material and the influence of the road roller compaction process.

[0032] Preferably, in step 1, the specific process for obtaining the dielectric constant ε of the roadbed fill is as follows:

[0033] Turn on the power switch 1 and observe the working status indicator 2 change from red to yellow, indicating that it has entered the standby working state. Select the appropriate electromagnetic wave signal frequency of the ground penetrating radar 6 of the ground penetrating radar mounted device 12 according to the depth of the roadbed compaction layer on site. Run the ground penetrating radar 6 and observe whether the frequency signal display 4 has started recording.

[0034] Then, the road roller is operated to start compaction. During the operation, the propagation time of the electromagnetic wave signal, i.e., the time t1+t2 of the electromagnetic wave signal being emitted and received, is collected in real time. The measurement distance of electromagnetic wave signals of different frequencies is different, so the measured depth of the roadbed fill is different. The formula for calculating the vertical distance H from the transmitting end of the ground penetrating radar 6 (i.e., the starting point of the measurement distance) to the test point (i.e., the ending point of the measurement distance) is as shown in equation (1):

[0035]

[0036] In equation (1), c is the propagation speed of the electromagnetic wave signal in the air; t1 is the propagation time of the electromagnetic wave signal in the air; v is the propagation speed of the electromagnetic wave signal in the roadbed fill material; t2 is the propagation time of the electromagnetic wave signal in the roadbed fill material; L is the distance between the transmitting end and the receiving end of the ground penetrating radar 6; as shown in equation (1), c is the propagation speed of the electromagnetic wave signal in the air; t1 is the propagation time of the electromagnetic wave signal in the roadbed fill material; v is the propagation speed of the electromagnetic wave signal in the roadbed fill material; t2 is the propagation time of the electromagnetic wave signal in the roadbed fill material; L is the distance between the transmitting end and the receiving end of the ground penetrating radar 6; as shown in equation (1), c is the propagation speed of the electromagnetic wave signal in the air; t1 is the propagation time of the electromagnetic wave signal in the air; v is the propag Figure 3 As shown;

[0037] The relationship between the propagation speed v of electromagnetic wave signals in the roadbed fill material and the dielectric constant ε is shown in equation (2):

[0038]

[0039] The dielectric constant ε of the roadbed fill is obtained by combining equations (1) and (2), as shown in equation (3):

[0040]

[0041] Preferably, in step 1, the specific process for obtaining the dielectric constant-volume moisture content function relationship of the roadbed fill material is as follows:

[0042] When the ground-penetrating radar device 12 emits electromagnetic waves, they will be refracted and reflected when they encounter different media. Water molecules will be polarized in the electric field and affect the dielectric properties of the roadbed filler within the path range. The dielectric constant is a parameter that characterizes the dielectric properties of a material. When the water content in the roadbed filler changes, the dielectric constant will also change accordingly.

[0043] (1) Establish the relationship between dielectric constant and mass moisture content: Take soil samples from the field for indoor testing, and calculate the dielectric constant ε of each group of samples according to formula (3); then fit the mass moisture content θv and dielectric constant ε corresponding to each group of tests with a formula. In order to ensure that the fitting effect is consistent with the actual measurement, a cubic polynomial is used to fit the relationship between dielectric constant and mass moisture content, as shown in formula (4):

[0044] θ V =lε 3 +mε 2 +nε (4)

[0045] In equation (4), l, m, and n are undetermined coefficients;

[0046] The indoor test is as follows: take several groups (no less than 10 groups, 14 groups in this embodiment) of roadbed filler samples of equal mass from the site and dry the samples completely (in this embodiment, they are baked in an oven at 105℃); then configure the moisture content of each group of samples according to the equal interval mass moisture content (6% to 20% in this embodiment, with a range of 2%), and calculate the dielectric constant ε of each group of samples according to formula (3); to ensure accuracy, measure each group of samples 3 times and take the average value, which is recorded as the dielectric constant value of the sample.

[0047] (2) Mass moisture content θ of roadbed fill V The conversion between the volumetric moisture content w of the roadbed fill material and the water content w is shown in equation (5):

[0048]

[0049] In equation (5), ρ d ρ is the dry density of the roadbed fill material; w The density of water;

[0050] (3) Combining equations (4) and (5), we obtain the dielectric constant-volume moisture content function relationship of the roadbed fill material:

[0051]

[0052] (4) Substitute the mass moisture content θv and dielectric constant ε corresponding to each group of experiments into equation (6) to obtain the values ​​of l, m and n, and obtain the dielectric constant-volume moisture content function relationship.

[0053] In step 1, the method for collecting the roller travel path data is as follows: Figure 4 As shown): The vehicle-mounted satellite signal receiver 11 and the global positioning satellite 10 form a satellite positioning system. The carrier phase differential technology of the satellite positioning system provides centimeter-level high-precision positioning function for coordinate positioning during the movement of the road roller. According to the construction scenario of the roadbed compaction site, the compaction site is gridded. The compaction process of the road roller is approximately a straight line. Taking the center position of the vibrating wheel as the starting point, the initial position of the road roller is recorded as (0,0). The direction of the road roller's movement is the positive x-axis, and the direction perpendicular to the road roller is the positive y-axis. The grid precision is specified according to the area of ​​the compaction site. The road roller's movement path and process are recorded, and the gridded road roller movement path data is calculated.

[0054] Step 2: Considering the influence of the spatiotemporal evolution of the volumetric moisture content w, a wheel-road coupling model is established by coupling the dynamic response equation of the subgrade fill material with the vibration force equation of the vibrating wheel, and simultaneously solving the volumetric moisture content equation, i.e., the vertical displacement solution u of the subgrade fill material. z Then, the vertical displacement u of the roadbed fill material is calculated. z By performing a second derivative, we obtain the solution α for the vertical acceleration of the subgrade fill material. z Next, the volumetric moisture content data of the subgrade fill material collected in step 1 is input into the wheel-road coupling model to obtain the vertical acceleration solution α of the subgrade fill material. z The maximum value α in each cycle maxBy combining the vibration acceleration α1 of the vibratory wheel, a compaction quality control index S is established, and the compaction quality control index S data is obtained. Then, the measured compaction quality control index S data and compaction degree K data are fitted to establish a functional relationship between compaction quality control index S and compaction degree K, and the compaction degree K data is obtained.

[0055] Preferably, in step 2, the specific process of establishing the wheel-road coupling model is as follows:

[0056] The wheel-road coupling model consists of two parts: a vibrating wheel and roadbed fill material. The dynamic response equation of the roadbed fill material is shown in equation (7):

[0057]

[0058] In equation (7), λ and μ are Larmor constants. v1 is the Poisson's ratio of the vibratory wheel material, E1 is the Young's modulus of the vibratory wheel material, v2 is the Poisson's ratio of the roadbed filler; ▽ is the Laplace operator; u is the displacement component of a point in the roadbed filler; θ is the volumetric strain; ρ is the density of the roadbed filler. The second derivative of the displacement component at a point in the subgrade fill material; σ ij ε represents the stress component at a certain point in the roadbed fill material; ij δ represents the strain component at a certain point in the roadbed fill material. ij For the Kronek component.

[0059] The calculation method for the Poisson's ratio v2 of the subgrade fill is as follows: Take the subgrade fill and prepare a sample. Perform a shear test according to the "Standard for Geotechnical Testing Methods": Place the soil sample in a ring cutter and record the inner diameter L1 and height L2. Place the tester on a horizontal platform and calibrate the position of the tester to ensure its horizontality. Apply shear force to cause shear deformation of the soil sample. Apply shear force again and record the shear deformation ΔL1 and vertical deformation ΔL2. To improve the accuracy of the measurement results, repeat 5 sets of tests and take the average value. The calculation formula for the Poisson's ratio v2 of the subgrade fill is shown in formula (8):

[0060]

[0061] The vibration force equation of the vibratory roller is: According to the roadbed compaction mechanism, during the construction stage, the basic principle of roadbed vibratory compaction is to use the mechanical self-weight and the excitation force generated by the vibrator to apply continuous sinusoidal impact to the roadbed fill material to expel gas or liquid. When the roller compacts the roadbed fill material, the shape of the vibratory roller acting on the roadbed surface is approximately rectangular, and the stress equation of the self-weight and excitation force is shown in equation (9):

[0062]

[0063] In equation (9), m1 is the mass of the frame, M0 is the mass of the vibrating wheel, g is the acceleration due to gravity, and F d ω is the excitation force of the vibrating wheel, w0 is the rotational angular velocity, α is the length of the compaction mark, and b is the width of the compaction mark.

[0064] The width b of the compaction mark left by the vibratory wheel on the ground during the operation of the road roller will change with the excitation force and the resilient modulus. Based on the Hertzian principle, the width b of the compaction mark is shown in equation (10):

[0065]

[0066] In equation (10), R is the radius of the vibrating wheel, and E* is the equivalent modulus; the equivalent modulus E* is calculated as shown in equation (11):

[0067]

[0068] In equation (11), E1 is the Young's modulus of the vibratory wheel material, E2 is the resilient modulus of the roadbed filler, and v1 is the Poisson's ratio of the vibratory wheel material.

[0069] The volumetric moisture content w is an important influencing factor of the resilient modulus E2 of the subgrade fill material, and the resilient modulus E2 of the subgrade fill material is an important influencing factor of the compaction degree. Therefore, the water-sensitive resilient modulus equation is introduced, as shown in equation (12):

[0070]

[0071] In equation (12), k1 and k2 are undetermined coefficients. The resilient modulus E2 of the roadbed fill material under different volume moisture contents is measured by indoor rebound hammer test, and then the values ​​of k1 and k2 are obtained by substituting them into equation (12).

[0072] Preferably, in step 2, the operation of the indoor rebound hammer test is as follows: take several groups of samples from the subgrade fill material at the site (the number of groups should not be less than 5 groups; in this embodiment, the number of groups is 5%, 8%, 11%, 14%, 17%, and 20%, respectively), with each group of samples having equal mass and volume; place the samples until they are completely dry (in this embodiment, they are baked in an oven at 105°C for 12 hours), and then prepare the samples according to the moisture content; place the samples with different volumetric moisture contents on the test plate and lift the rebound hammer from above the sample to a certain height and drop it, repeating this process until the rebound values ​​at different heights are obtained, record the data to obtain the relationship between the rebound value and the drop height, and obtain the rebound curve; calculate the rebound modulus of the sample based on the rebound curve, and then establish a rebound modulus-volume moisture content curve through the rebound value and moisture content of the samples taken, to obtain the values ​​of k1 and k2.

[0073] Establishing a wheel-road coupled model requires solving the dynamic response equation and constitutive equation of the subgrade fill material simultaneously. The constitutive equation of the subgrade fill material is as follows:

[0074]

[0075] Considering that the contact surface between the vibratory wheel and the roadbed is the roadbed surface, and tangential friction is not considered, the boundary conditions are set as follows: the horizontal contact stress is zero and the vertical contact stress is equal. The boundary conditions are shown in Equation (14):

[0076]

[0077] By combining equations (7) to (14), we obtain the solution u of the vertical displacement of the roadbed fill material in the wheel-road coupling model. z ;

[0078]

[0079] In equation (15), the vertical displacement u of the roadbed fill material is solved. z coefficient:

[0080] Ω1=2(η 2 +ξ 2 )-ρs 2 i1,

[0081] Preferably, in step 2, the vertical displacement u of the roadbed fill material is solved. z By performing a second derivative, we obtain the solution α for the vertical acceleration of the subgrade fill material. z As shown in equation (16):

[0082]

[0083] In equation (16), η, ξ, and s are the symbols corresponding to the Fourier transforms of x, y, and t, respectively; σ1~σ 18 r1 to r8 are coefficients.

[0084] σ2=σ9σ7-σ8σ5σ6,

[0085]

[0086] σ 12 =η 2 +ξ 2 -σ 14 , σ 13 =η 2 +ξ 2 -σ15 ,

[0087] Preferably, in step 2, the specific method for establishing the compaction quality control index S is as follows:

[0088] The vibration acceleration α1 of the vibrating wheel is shown in equation (17):

[0089]

[0090] In equation (17), A0 is the nominal amplitude of the vibrating wheel; w0 is the angular velocity of the eccentric rotor of the vibrating wheel; and g is the acceleration due to gravity.

[0091] The compaction quality control index S is shown in equation (18):

[0092]

[0093] Preferably, in step 2, a test section longer than 100m is selected for on-site compaction simulation test. The on-site compaction simulation test is strictly conducted in accordance with the "JTG E60-2008 Highway Subgrade and Pavement Field Test Procedure": The ground-penetrating radar mounting device 12 is installed at the bottom of the roller, the roller is started to detect the moisture content of the test section and calculate the compaction quality control index S according to formula (18); a sampling point is selected every fixed distance (3m in this embodiment) from the starting compaction position to measure and record the compaction degree K. The compaction degree K is measured in accordance with the "JTG 3430-2020 Highway Geotechnical Test Procedure"; then the measured compaction quality control index S data and compaction degree K data are fitted to establish the functional relationship between compaction quality control index S and compaction degree K as shown in formula (19):

[0094] K = C(S) (19)

[0095] In equation (19), C is the fitting function between K and S.

[0096] Step 3: According to the "JTT1127-2017 Technical Conditions for Continuous Compaction Control System of Highway Subgrade Filling Engineering" and the requirement that the intelligent compaction process is simple to operate, the compaction site is divided into several first-level areas, each first-level area is divided into several second-level areas, and each second-level area is divided into several third-level areas, presenting a three-dimensional spatial and temporal distribution of the area.

[0097] Preferably, in step 3, the first-level region is a compacted section with a length of not less than 100m, and the first-level regions are numbered sequentially from the beginning as 0001, 0002, 0003, 0004, etc.; the length of the second-level region is one-tenth of that of the first-level region, and they are numbered sequentially in the same direction as the first-level regions as ① to ⑩; the third-level region is a three-dimensional space in the length, width, and depth (depth is the thickness of the compacted layer), and in this embodiment, each third-level region is a cube of 0.1 to 0.5m.

[0098] In this embodiment, as Figure 5 As shown, the first-level area is a compaction section with a length of 100m and a width equal to the width of the vibrating wheel; the second-level area is each 10m segment in the first-level area, and the second-level areas are numbered (①~⑩); the third-level area is a cube with a side length of 0.1m.

[0099] Step 4: Based on the three-level regions divided in Step 3, plot the compaction degree K data obtained in Step 2 into a spatiotemporal distribution cloud map of compaction degree; then, comprehensively evaluate the spatiotemporal distribution cloud map of compaction degree using the subgrade full-face compaction quality evaluation method: if there are areas where the compaction quality does not meet the standards, adjust the construction process parameters of the road roller and check whether there are any uncertain factors affecting the compaction effect in that area, and deal with them immediately before proceeding to the next compaction pass; when the compaction quality of all first-level regions meets the compaction requirements, the subgrade full-face compaction quality evaluation is qualified, and compaction is completed.

[0100] Preferably, in step 4, the method for evaluating the compaction quality of the entire roadbed working face is as follows:

[0101] The third-level area is color-coded as follows: Third-level areas with a compaction degree ≥ 95% are marked in green, indicating that the third-level area meets the compaction requirements; third-level areas with a compaction degree ≤ 85% and < 95% are marked in yellow, indicating that the third-level area does not meet the compaction requirements but can be achieved with continued compaction; third-level areas with a compaction degree < 85% are marked in red, indicating that the third-level area does not meet the requirements and the difference is significant, in which case it is necessary to check whether there are any uncertain factors affecting the compaction effect in the third-level area.

[0102] Second-level area color coding: All tertiary areas within a given secondary area are assessed according to the standard JTG 3450-2019 Highway Subgrade and Pavement Field Testing Procedures: If the compacted volume within a secondary area is ≥ 97% of the total volume, it is marked green, indicating that the secondary area has met the compaction requirements; if 90% ≤ the compacted volume within a secondary area is < 97% of the total volume, it is marked yellow, indicating that the secondary area has not met the compaction requirements and further compaction could achieve the desired results; if the compacted volume within a secondary area is < 90% of the total volume, it is marked red, indicating that the secondary area has not met the requirements and the compaction is poor.

[0103] First-level area color coding: If all second-level areas in the first-level area are qualified, it is marked in green, indicating that the first-level area has met the compaction standard; if there are ≤2 unqualified second-level areas in the first-level area, it is marked in yellow, indicating that the first-level area has not met the compaction standard and that continued compaction can meet the compaction requirements; if there are >2 unqualified second-level areas in the first-level area, it is marked in red, indicating that the first-level area has not met the standard and the compaction is too poor.

[0104] Any aspects not covered in this invention are applicable to existing technologies.

Claims

1. A smart compaction method for roadbed considering the spatiotemporal evolution of filler moisture content, characterized in that, The method includes the following steps: Step 1: Collect the data required for on-site compaction, including construction process parameter data, subgrade fill material parameter data, subgrade fill material volumetric moisture content data, and roller travel path data; Step 2, consider volumetric moisture content w Influenced by the spatiotemporal evolution law, by coupling the dynamic response equation of the roadbed fill material with the vibration force equation of the vibrating wheel, and combining it with the volumetric water content, a wheel-road coupling model is established, namely the vertical displacement solution of the roadbed fill material. u z Then, the vertical displacement of the roadbed fill material is solved. u z By performing a second derivative, we obtain the solution for the vertical acceleration of the subgrade fill material. a z Next, the volumetric moisture content data of the subgrade fill material collected in step 1 is input into the wheel-road coupling model to obtain the vertical acceleration solution of the subgrade fill material. a z Maximum value in each cycle a max And combined with the vibration acceleration of the vibrating wheel a 1. Establish compaction quality control indicators S In order to obtain the compaction quality control indicators. S Data; then compare the measured compaction quality control indicators. S Data and compaction degree K The data were fitted to establish compaction quality control indicators. S With compaction degree K The functional relationship between them is used to determine the compaction degree. K data; Step 3: Divide the compacted site into several primary zones, then divide each primary zone into several secondary zones, and finally divide each secondary zone into several tertiary zones. Step 4: Based on the three-level zones defined in Step 3, apply the compaction degree obtained in Step 2. K The data is plotted into a spatiotemporal distribution cloud map of compaction degree; then, the spatiotemporal distribution cloud map of compaction degree is comprehensively evaluated using the subgrade full-face compaction quality evaluation method: if there are areas where the compaction quality does not meet the standards, the construction process parameters of the road roller are adjusted and it is checked whether there are any uncertain factors affecting the compaction effect in that area and dealt with in a timely manner; when the compaction quality of all first-level areas meets the compaction requirements, the subgrade full-face compaction quality evaluation is qualified, and compaction is completed; In step 4, the specific method for evaluating the compaction quality of the entire roadbed working face is as follows: The third-level area is color-coded as follows: Third-level areas with a compaction degree ≥ 95% are marked in green, indicating that the third-level area meets the compaction requirements; third-level areas with a compaction degree ≤ 85% and < 95% are marked in yellow, indicating that the third-level area does not meet the compaction requirements but can achieve them with continued compaction; third-level areas with a compaction degree < 85% are marked in red, indicating that the third-level area does not meet the requirements and the difference is significant, in which case it is necessary to check whether there are any uncertain factors affecting the compaction effect in the third-level area. Second-level area color coding: When the compacted volume of the second-level area is ≥ 97% of the total volume, it is marked in green, indicating that the compaction of the second-level area meets the standard; when the compacted volume of the second-level area is < 97% of the total volume (≤ 90% of the total volume), it is marked in yellow, indicating that the compaction of the second-level area does not meet the standard and further compaction can achieve the compaction requirements; when the compacted volume of the second-level area is < 90% of the total volume, it is marked in red, indicating that the second-level area does not meet the standard and the compaction is too poor. First-level area color coding: If all second-level areas in the first-level area are qualified, it is marked in green, indicating that the first-level area has met the compaction standard; if there are ≤2 unqualified second-level areas in the first-level area, it is marked in yellow, indicating that the first-level area has not met the compaction standard and that continued compaction can meet the compaction requirements; if there are >2 unqualified second-level areas in the first-level area, it is marked in red, indicating that the first-level area has not met the standard and the compaction is too poor.

2. The intelligent compaction method for roadbed considering the spatiotemporal evolution of filler moisture content according to claim 1, characterized in that, In step 1, the construction process parameter data includes the frame mass. m 1. Mass of the vibrating wheel M 0. Vibrating wheel length a Poisson's ratio of the vibratory wheel material v 1. Young's modulus of the vibrating wheel material E 1. Vibration frequency of the vibrating wheel f and the nominal amplitude of the vibrating wheel A 0; Subgrade fill material parameter data includes the Poisson's ratio of the subgrade fill material. v 2; The method for collecting the volumetric moisture content data of the roadbed fill is as follows: the ground-penetrating radar mounted device (12) is installed on the bottom of the road roller; during the road roller's operation in the compaction site, the propagation time of the electromagnetic wave signal in the compaction path is measured in real time using the ground-penetrating radar mounted device (12), and then the dielectric constant ε of the roadbed fill is obtained by the dielectric constant calculation method, and then the dielectric constant ε is converted into volumetric moisture content data by the dielectric constant-volume moisture content function relationship of the roadbed fill. The method for collecting road roller travel path data is as follows: the vehicle-mounted satellite signal receiver (11) and the global positioning satellite (10) form a satellite positioning system, and the carrier phase differential technology of the satellite positioning system is used to provide high-precision positioning function for coordinate positioning during the road roller's travel; according to the roadbed compaction site construction scenario, the compaction site is gridded into coordinates, and the road roller's compaction process is approximately a straight line. Taking the center position of the vibrating wheel as the starting point, the initial position of the road roller is recorded as (0,0), and the direction of the road roller's travel is used as the coordinates. x The positive direction of the axis, perpendicular to the direction of the road roller is y In the positive axis direction, based on the specified grid precision according to the area of ​​the compacted site, the travel path and process of the road roller are recorded, and the road roller travel path data presented in grid coordinates is calculated.

3. The intelligent compaction method for roadbed considering the spatiotemporal evolution of filler moisture content according to claim 2, characterized in that, In step 1, the ground-penetrating radar mounting device (12) includes a power switch (1), a working status indicator (2), an automatic telescopic baffle (3), a frequency signal display (4), a ground-penetrating radar (6), a shock-absorbing spring (7), a mounting device housing (8), and a connecting rod (9). The connecting rod (9) is slidably mounted on the housing (8) of the mounting device and fixed by the rod fixing screw (5); the housing (8) of the mounting device is mounted on the bottom of the road roller via the connecting rod (9); the power switch (1), the working status indicator (2) and the frequency signal display (4) are mounted on the housing (8); the ground penetrating radar (6) is mounted inside the housing (8) of the mounting device via a shock-absorbing spring (7), the shock-absorbing spring (7) is used to ensure the stability of the ground penetrating radar (6) during operation; the ground penetrating radar (6) is equipped with an electromagnetic wave signal transmitter. The transmitter is used to transmit electromagnetic waves into the ground, and the receiver is used to receive the reflected electromagnetic wave signals. The automatic telescopic baffle (3) is slidably installed at the bottom of the housing (8) of the mounting device, located at the ground penetrating radar (6). When the device is working, the automatic telescopic baffle (3) retracts, so that the ground penetrating radar (6) is exposed and facing the ground, and begins to work. When the device is closed, the automatic telescopic baffle (3) extends and cooperates with the housing (8) of the mounting device to enclose the ground penetrating radar (6) inside the housing (8) of the mounting device, protecting the ground penetrating radar (6). The power switch (1) is a control button used to control the start and stop of the ground-penetrating radar mounted device (12); the working status indicator (2) includes three lights: red, yellow and green. Red indicates that the machine is stopped, yellow indicates that it is in standby mode, and green indicates that it is in working mode; the frequency signal display (4) is an LED display screen used to display the collected volumetric water content information.

4. The intelligent compaction method for roadbed considering the spatiotemporal evolution of filler moisture content according to claim 2, characterized in that, In step 1, the specific process of obtaining the dielectric constant ε of the roadbed fill is as follows: Select the appropriate electromagnetic wave signal frequency of the ground-penetrating radar (6) of the ground-penetrating radar mounted device (12) according to the depth of the compacted subgrade layer on site, and operate the ground-penetrating radar (6); then operate the road roller to start compaction, and collect the propagation time of the electromagnetic wave signal in real time during the operation. t 1 +t 2; The measurement distance of electromagnetic wave signals of different frequencies is different, so the measured depth of roadbed fill is different. The formula for calculating the vertical distance H from the transmitter of the ground penetrating radar (6) to the test point is shown in equation (1): （1） In equation (1), c is the speed of electromagnetic wave signal in air; t1 is the propagation time of electromagnetic wave signal in air; v is the speed of electromagnetic wave signal in roadbed filler; t2 is the propagation time of electromagnetic wave signal in roadbed filler; and L is the distance between the transmitter and receiver of the ground penetrating radar (6). The relationship between the propagation speed v of the electromagnetic wave signal in the roadbed fill and the dielectric constant ε is shown in equation (2): （2） The dielectric constant ε of the roadbed fill is obtained by combining equations (1) and (2), as shown in equation (3): （3）。 5. The intelligent compaction method for roadbed considering the spatiotemporal evolution of filler moisture content according to claim 4, characterized in that, In step 1, the specific process of obtaining the dielectric constant-volume moisture content function relationship of the roadbed fill material is as follows: (1) Establish the dielectric constant-mass moisture content function relationship: Take several groups of roadbed filler samples of equal mass from the site and dry the samples completely; then configure the moisture content of each group of samples according to the mass moisture content at equal intervals, and calculate the dielectric constant ε of each group of samples according to formula (3); then calculate the mass moisture content corresponding to each group of tests. θ The formulas for v and dielectric constant ε are fitted, and the relationship between dielectric constant and mass moisture content is fitted using a cubic polynomial, as shown in equation (4): （4） In equation (4), l , m , n These are coefficients to be determined; (2) Moisture content of roadbed fill material θ V Volumetric moisture content of roadbed fill w The transformation between them is shown in equation (5): （5） In equation (5), ρ d This refers to the dry density of the roadbed fill material. ρ w The density of water; (3) Combining equations (4) and (5), we obtain the dielectric constant-volume moisture content function relationship of the roadbed fill material: （6） (4) The moisture content corresponding to each group of tests θ Substituting v and dielectric constant ε into equation (6), we can then obtain... l , m , n The value of is used to obtain the dielectric constant-volume water content function relationship.

6. The intelligent compaction method for roadbed considering the spatiotemporal evolution of filler moisture content according to claim 1, characterized in that, In step 2, the specific process of establishing the wheel-road coupling model is as follows: The dynamic response equation of the subgrade fill is shown in equation (7): （7） In equation (7), λ , μ Let Lamo's constant be 1. , ; v 1 represents the Poisson's ratio of the vibratory wheel material. E 1 represents the Young's modulus of the vibratory wheel material. v 2 represents the Poisson's ratio of the roadbed fill material; ▽ represents the Laplace operator; u This represents the displacement component of a point on the roadbed fill material. θ For the body strain; ρ This refers to the density of the roadbed fill material. The second derivative of the displacement component at a point in the subgrade fill material; σ ij ε represents the stress component at a certain point in the roadbed fill material; ij δ represents the strain component at a certain point in the roadbed fill material. ij For the Kronek component; Poisson's ratio of roadbed fill v The formula for calculating 2 is shown in equation (8): （8） The vibration force equation of the vibratory roller is: When the roller compacts the roadbed fill material, the shape of the vibratory roller acting on the roadbed surface is approximately rectangular. The stress equation of the self-weight and excitation force is shown in equation (9): （9） In equation (9), m 1 represents the frame mass. M 0 represents the mass of the vibrating wheel. g It is the acceleration due to gravity. F d The excitation force of the vibrating wheel, w 0 represents the rotational angular velocity. a The length of the crushing mark. b The width of the crush mark; The width of the compaction marks left on the ground by the vibratory wheel of the road roller during operation b The width of the compaction mark varies with the excitation force and the spring modulus, based on Hertzian principles. b As shown in equation (10): （10） In equation (10), R The radius of the vibrating wheel, E * represents the equivalent modulus; equivalent modulus E *The calculation is shown in equation (11): （11） In equation (11), E 1 represents the Young's modulus of the vibrating wheel material. 、E 2 represents the resilient modulus of the roadbed fill material. v 1 represents the Poisson's ratio of the vibratory wheel material; Volumetric moisture content w It is the resilient modulus of the roadbed fill. E 2. Important influencing factors, and the resilient modulus of roadbed fill. E 2 is an important influencing factor on compaction degree. Therefore, the water-sensitive resilient modulus equation is introduced, as shown in equation (12): （12） In equation (12), k 1 、k 2 represents an undetermined coefficient; the resilient modulus of the roadbed fill material under different volumetric moisture contents was measured using an indoor rebound hammer test. E 2. Substitute into equation (12) to obtain k 1 and k The value of 2; Establishing a wheel-road coupled model requires solving the dynamic response equation and constitutive equation of the subgrade fill material simultaneously. The constitutive equation of the subgrade fill material is as follows: （13） Considering that the contact surface between the vibratory wheel and the roadbed is the roadbed surface, and tangential friction is not considered, the boundary conditions are set as follows: the horizontal contact stress is zero and the vertical contact stress is equal. The boundary conditions are shown in Equation (14): （14） By combining equations (7) to (14), we obtain the displacement solution of the wheel-road coupling model, i.e., the vertical displacement of the roadbed fill. u z ; （15） In equation (15), the vertical displacement solution of the subgrade fill material is... u z coefficient: , , , , , , , , , ; In step 2, the vertical displacement of the roadbed fill material is solved. u z By performing a second derivative, we obtain the solution for the vertical acceleration of the subgrade fill material. a z As shown in equation (16): （16） In equation (16), η , ξ , s , respectively x , y , t The sign corresponding to the Fourier transform; σ 1 ~σ 18 , r 1 ~r 8 is the coefficient. , , , , , , , , , , , , , , , , , ; , , , , , , , .

7. The intelligent compaction method for roadbed considering the spatiotemporal evolution of filler moisture content according to claim 6, characterized in that, In step 2, the specific operation of the indoor rebound hammer test is as follows: Several sets of samples are taken from the subgrade fill material at the site, each set containing equal mass and volume; the samples are completely dried, and then prepared according to their volumetric moisture content; samples with different volumetric moisture contents are placed on a test plate, and the rebound hammer is raised from above the sample to different heights and dropped, repeating this process until rebound values ​​at different heights are obtained. The relationship between the rebound value and the drop height is obtained, and a rebound curve is obtained; then, the rebound modulus of the sample is calculated based on the rebound curve; finally, a rebound modulus-volume moisture content curve is established using the rebound values ​​and volumetric moisture contents of the samples taken, to obtain... k 1 and k The value of 2.

8. The intelligent compaction method for roadbed considering the spatiotemporal evolution of filler moisture content according to claim 1, characterized in that, In step 2, establish compaction quality control indicators. S The specific methods are as follows: Vibration acceleration of the vibrating wheel a 1. As shown in equation (17): （17） In equation (17), A0 is the nominal amplitude of the vibrating wheel; w0 is the angular velocity of the eccentric rotor of the vibrating wheel; and g is the acceleration due to gravity. Compaction quality control indicators S As shown in equation (18): （18）； In step 2, a test section longer than 100m is selected for on-site compaction simulation test: the ground-penetrating radar mounting device (12) is installed at the bottom of the roller, the roller is started to detect the moisture content of the test section and the compaction quality control index S is calculated according to formula (18); a sampling point is selected at fixed intervals from the starting compaction position to measure and record the compaction degree K; then the measured compaction quality control index is analyzed. S Data and compaction degree K The data were fitted to establish compaction quality control indicators. S With compaction degree K The functional relationship between them is shown in equation (19): （19）。 9. The intelligent compaction method for roadbed considering the spatiotemporal evolution of filler moisture content according to claim 1, characterized in that, In step 3, the first-level area is a compacted section with a length of not less than 100m, and the first-level areas are numbered sequentially from the beginning; the second-level area is one-tenth the length of the first-level area, and is numbered sequentially in the same direction as the first-level area; the third-level area is a three-dimensional space in the length, width and depth directions.

Images