A platform-based monitoring method for highway roadbed settlement and convergence

Abstract

The present invention discloses a platform-type highway roadbed settlement and convergence monitoring method, which includes setting a monitoring cross section and arranging monitoring points. Each monitoring cross section is equipped with a sixth level monitoring element and a plurality of reflector monitoring elements, so as to ensure that the measuring points on each monitoring cross section are strictly located on the designed cross section line; each area has at least one reflector monitoring element; leveling measurement, relative height difference and horizontal distance measurement are performed separately, and all sixth leveling points are leveled together using a level; the relative height difference and horizontal distance between the reflector measuring points in each cross section are measured using a total station; leveling measurement, relative height difference and horizontal distance measurement are performed at regular intervals, and compared with initial values ​​to obtain roadbed settlement and roadbed convergence data, thereby judging the stability of the roadbed.

Description

Technical Field

[0001] The invention belongs to the technical field of roadbed monitoring, and in particular relates to a platform-type highway roadbed settlement and convergence monitoring method. Background Art

[0002] During the construction of long highways, especially those with significant elevation differences between the left and right sides of the roadbed (referred to herein as split-platform highways), visibility between the left and right sides is often difficult or even nonexistent when monitoring subgrade settlement. This is especially true after the highway is operational, when regulatory authorities, for safety reasons, prohibit monitoring personnel from crossing the highway to conduct tests. This presents significant challenges for monitoring subgrade settlement. Currently, commonly used subgrade settlement monitoring methods include settlement plates / settlement nails, layered settlement meters, and cross-section tubes. Numerous scholars have systematically studied these methods, achieving promising results. However, these methods are generally applicable to monolithic highways with minimal elevation differences between the left and right sides, and are not suitable for split-platform highways with significant subgrade elevation differences. Currently, there is limited research and reporting on subgrade settlement and convergence monitoring methods for split-platform highways. Summary of the Invention

[0003] The purpose of the present invention is to overcome the shortcomings of the existing technology and propose a platform-based highway roadbed settlement and convergence monitoring method. The method is based on the joint monitoring of a precision level and a precision total station. Specifically, the settlement data of the monitoring points on a certain longitudinal line are obtained by second-class leveling and used as the reference point of each monitoring cross-section. At the same time, the precision total station is used to synchronously obtain the relative height difference and horizontal distance between the measuring points in each cross-section. Finally, the settlement data of all monitoring points and the left / right roadbed convergence data can be obtained through joint calculation. The method innovatively solves the technical problems of poor visibility conditions, no crossing of the highway for testing during the operation period, difficulty in protecting monitoring points, low operating efficiency, and single result data, and achieves good monitoring effects.

[0004] A platform-type highway roadbed settlement and convergence monitoring method, comprising:

[0005] Step 1: Set up monitoring cross sections and deploy monitoring points

[0006] According to the design requirements, n monitoring cross sections are set at a certain interval in the entire monitoring section, and the monitoring cross sections include at least: the right road area, the middle isolation zone area, and the left road area;

[0007] Each monitoring cross section is equipped with a sixth level monitoring element and multiple reflector monitoring elements, each of which has the same structure. During installation, each monitoring element is precisely positioned using a GNSS receiver to ensure that the measuring points on each monitoring cross section are strictly located on the designed cross section line. The sixth level monitoring element includes a sixth reflector measuring point and a sixth level measuring point. Each of the reflector monitoring elements has a reflector measuring point.

[0008] Each area has at least one reflective sheet monitoring element;

[0009] The sixth level monitoring element of each monitoring cross section is located on the slope crash wall / hard ground in the left / right road area, and serves as both a settlement point and a reflector.

[0010] Step 2: Simultaneously perform leveling, relative height difference, and horizontal distance measurements

[0011] (1) Leveling

[0012] A level is set up along the emergency lane of the left / right road area where the sixth leveling monitoring element is located according to the second-class leveling measurement specifications. The sixth leveling point of the sixth leveling monitoring element of each monitoring cross section is leveled using the level. The elevation value of the sixth leveling point of each monitoring cross section is obtained through calculation, which provides a basis for calculating the settlement of the reflector measuring point of each monitoring cross section.

[0013] (2) Relative height difference and horizontal distance measurement

[0014] Setting up precision total stations in the emergency lanes of the left and right road areas of each monitoring cross section to obtain the height differences between the reflector measuring points, wherein one of the total stations is used to obtain the height difference between the sixth reflector measuring point and an adjacent reflector measuring point, and the other total station is used to obtain the height difference between the other reflector measuring points except the sixth reflector measuring point;

[0015] The elevation value of each reflector measuring point in each monitoring cross section is expressed by the precise elevation of the sixth leveling point of the monitoring cross section, the precise elevation difference between the reflector measuring points, and a fixed unknown constant between the sixth leveling point and its reflector measuring points. In other words, the elevation value mentioned here is actually an elevation expression containing a fixed unknown constant (because the fixed unknown constant is offset in the subsequent calculation of settlement, it will not affect the monitoring results); the initial measured value is used as the initial elevation value of each reflector measuring point;

[0016] Based on the plane coordinates between the measuring points of each reflector obtained by the total station in each monitoring cross section and the distance formula between the two points, the horizontal distance of the left-side road / right-side road area is calculated, and the initial measured value is used as the initial horizontal distance of the left-side road / right-side road area;

[0017] (3) Calculation of roadbed settlement and roadbed convergence

[0018] According to the project requirements, the measurements of (1) and (2) in step 2 are carried out at regular intervals;

[0019] Subtract the initial elevation value from the elevation value of each measuring point to obtain the subgrade settlement data of all measuring points;

[0020] The roadbed convergence data of all monitored cross sections can be obtained by subtracting the initial horizontal distance from the current left / right road area horizontal distance;

[0021] Step 3: Determine the stability of the roadbed based on the roadbed settlement and roadbed convergence data obtained in step 2.

[0022] Furthermore, the side slopes and median strips of the left and right road areas are provided with concrete crash barriers of a certain height.

[0023] Furthermore, the sixth level monitoring element includes a sinker nail and a steel sheet, the sinker nail includes a rod and a round nail cap located on the top thereof, the rod of the sinker nail is provided with a reflective sheet, and the reflective sheet faces the total station; the reflective sheet of the sixth level monitoring element serves as the sixth reflective sheet measuring point, and its round nail cap serves as the measuring point for leveling measurement, that is, the sixth leveling measuring point.

[0024] Furthermore, the reflector monitoring element includes a rod and a reflector fixed to the rod, the reflector faces the total station; the reflector located thereon serves as a reflector measuring point.

[0025] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0026] In view of the special working conditions and various restrictive requirements of platform-type expressways, a roadbed settlement monitoring method based on the joint measurement of precision levels and precision total stations has been studied and developed. This method can simultaneously solve many difficult problems in the deformation monitoring of roadbeds on platform-type expressways, such as poor visibility conditions, prohibition of crossing the highway for testing during operation, difficulty in protecting monitoring points, low operating efficiency, and single data results. It can also quickly and synchronously obtain roadbed settlement and roadbed convergence monitoring data, thereby providing a solid data foundation for accurately analyzing and judging the causes of roadbed cracking, effectively guiding on-site construction, and optimizing organizational design. It has good universality and promotion value. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1a 1 is a schematic structural diagram of a cross section of a highway roadbed in an embodiment; Figure 1b Schematic diagram of a monitoring point of a cross section of a highway roadbed in an embodiment;

[0028] Figure 22. It is a schematic structural diagram of a highway roadbed in an embodiment;

[0029] Figure 3 A schematic diagram showing the structure of the sixth level monitoring element;

[0030] Figure 4 A schematic diagram showing the structure of a reflector monitoring element is shown;

[0031] Figure 5 The settlement time history curve of section K19+100 is shown;

[0032] Figure 6 Shows the differential settlement between two adjacent points on the roadbed cross section;

[0033] Figure 7 The K19+100 left and right amplitude convergence time curves are shown.

[0034] 1: First reflector monitoring element 2: Second reflector monitoring element

[0035] 3: Third reflector monitoring element 4: Fourth reflector monitoring element

[0036] 5: Fifth reflector monitoring element 6: Sixth level monitoring element

[0037] Fn,1: First reflector measuring point Fn,2: Second reflector measuring point

[0038] Fn,3: The third reflector measuring point Fn,4: The fourth reflector measuring point

[0039] Fn,5: Fifth reflector measuring point Fn,6: Sixth reflector measuring point

[0040] Sn: Sixth leveling point 7: total station

[0041] 8: Elevation control point 9: Reinforced concrete crash barrier

[0042] 10: Rod 11: Reflective sheet

[0043] 12: Round nail cap DETAILED DESCRIPTION

[0044] The technical solution of the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. The specific embodiments described are only used to explain the present invention and are not intended to limit the present invention.

[0045] It should be noted that the terms "first", "second", "third", etc. in the description and claims of the present invention are only used to distinguish different objects, rather than to describe a specific order.

[0046] It should also be noted that the following specific embodiments may be combined with each other, and the same or similar concepts or processes therein may not be repeated in some embodiments.

[0047] A platform-based highway subgrade settlement and convergence monitoring method was developed for monitoring the subgrade of a Tianjin highway located in a coastal soft soil region. The monitored section is 16.62 kilometers long.

[0048] The specific steps include:

[0049] Step 1: Set up monitoring cross sections and deploy monitoring points

[0050] According to the design requirements, n monitoring cross sections are set up every 200m (100m for high fill section) along the line, i.e. 1, 2, 3...n. Figure 1a As shown, the monitoring cross-section of the entire monitoring section, from right to left, consists of the existing railway area, right-hand road area, central median strip area, left-hand road area, left slope protection area, patrol road area, and existing river area. The central median strip area and left slope protection area are ramps, while a ramp separates the river area and patrol road area. The railway structure in the railway area is a roadbed / viaduct. The top of the existing track in the railway area is approximately 2 meters above the design elevation of the right-hand road area and is approximately 10 to 60 meters from the right-hand road edge. The design widths of the left and right road areas are approximately 14 meters. The design elevation of the right-hand road area is approximately 2 meters higher than that of the left-hand road area; the design elevation of the left-hand road area is approximately 2 meters higher than the design elevation of the patrol road area's roadbed; and the design elevation of the patrol road area's roadbed is approximately 2 meters higher than the riverbed in the river area. To address flood control needs, three concrete crash barriers 9 were installed on the slopes and central median strip of the left and right-hand road areas of this monitoring section. Of course, concrete crash barriers may not be installed in other highways in actual operation.

[0051] like Figure 2 As shown, a sixth level monitoring element 6 and five reflector monitoring elements are arranged in each monitoring cross section, namely the first reflector monitoring element 1, the second reflector monitoring element 2, the third reflector monitoring element 3, the fourth reflector monitoring element 4, and the fifth reflector monitoring element 5. Each reflector monitoring element has the same structure but different positions. In order to improve the accuracy of the settlement and roadbed convergence data of the left and right roads, each monitoring element uses a GNSS receiver for precise positioning to ensure that the measuring points on each monitoring cross section are strictly located on the designed cross section line. Among them, as Figure 3As shown, the sixth level monitoring element 6 includes a sinker nail and a steel sheet. The sinker nail is a round-headed stainless steel sinker nail with a length of 150 mm and a diameter of 16 mm, including a rod 10 and a round nail cap 12 at the top. A 3 mm thick, 40 mm square stainless steel sheet is welded on the sinker nail. A 40 mm square reflective sheet 11 is attached to the stainless steel sheet, and the reflective sheet 11 is facing the total station. The sixth level monitoring element 6 serves as a geometric leveling settlement monitoring point and also as a reflective sheet measuring point during total station testing. It is a reference point / reference point for estimating the settlement of other measuring points in the same cross section. The reflective sheet of the sixth level monitoring element 6 serves as the sixth reflective sheet measuring point Fn,6, and its round nail cap serves as the measuring point for leveling measurement, i.e., the sixth leveling measuring point Sn. As shown Figure 4 As shown, the reflector monitoring element includes a rod and a steel sheet welded thereon, the rod 10 is a stainless steel rod with a length of 150 mm and a diameter of 12 mm, the steel sheet is a stainless steel sheet with a thickness of 3 mm and a square size of 40 mm, a reflector 11 with a square size of 40 mm is attached to the stainless steel sheet, and the reflector 11 is directed toward the total station 7. The reflectors on the first to fifth reflector monitoring elements serve as the first, second, third, fourth, and fifth reflector measuring points Fn,1, Fn,2, Fn,3, Fn,4, and Fn,5. The reflector monitoring element is used to obtain the relative height difference and horizontal distance between different measuring points in the same cross section through the reflector mode test of the precision total station. The schematic diagram of each measuring point is shown in FIG. Figure 1b The elevation values ​​of each cross-section measuring point are represented by HFn,1, HFn,2, HFn,3, HFn,4, HFn,5, and HFn,6 respectively.

[0052] A first reflector monitoring element 1 and a second reflector monitoring element 2 are respectively arranged at the two ends of the patrol road area. The first reflector monitoring element 1 is close to the river area, and the second reflector monitoring element 2 is close to the left slope protection area. The bottoms of the rods of the two reflector monitoring elements are fixed to the road surface of the patrol road area and are perpendicular to the road surface of the patrol road area.

[0053] A third reflector monitoring element 3 and a fourth reflector monitoring element 4 are respectively provided at the two ends of the left road area. The third reflector monitoring element 3 is fixed on the top of the reinforced concrete crash barrier 9 close to the left slope protection area. The fourth reflector monitoring element 4 is close to the middle isolation zone area, and the bottom of the rod of the fourth reflector monitoring element 4 is fixed to the road surface of the left road area and is perpendicular to the road surface of the left road area.

[0054] The fifth reflector monitoring element 5 and the sixth level monitoring element 6 are respectively set in the right road area. The sixth level monitoring element 6 is fixedly installed on the reinforced concrete crash barrier on the right side slope of the right road which is suitable for monitoring personnel to access and stable. After drilling, the settlement nails are horizontally fixed on the reinforced concrete crash barrier 9; the fifth reflector monitoring element 5 is fixed on the top of another reinforced concrete crash barrier 9.

[0055] Step 2: Perform leveling, relative height difference, and horizontal distance measurements

[0056] (1) Leveling

[0057] A precision level (not shown in the figure, a Tianbao DINI03 electronic level with a nominal accuracy of 0.3mm / km) is installed on the right emergency lane of the right road area. In accordance with the requirements of the second-class precision leveling specifications, an elevation control point 8 is arranged every 2km along the way as the basis for calculating the elevation value. The round nail cap of the sixth leveling monitoring element 6 of each monitoring cross-section is leveled according to the attached leveling line using a precision level. The elevation value of the sixth leveling measuring point S1-Sn of each monitoring cross-section is obtained by solution, which provides a benchmark for calculating the settlement of the 5 reflector measuring points of each monitoring cross-section.

[0058] (2) Relative height difference and horizontal distance measurement

[0059] To ensure the aiming accuracy, a precision total station 7 (using Topcon MS05 and Leica TM50 total stations with reflector measurement mode, readings up to 0.1mm, angle measurement accuracy of 0.5″, and distance measurement accuracy of 0.5mm+10-6D (D is the measurement distance in km)) was set up about 30m in front of each monitoring cross section of the left and right emergency lanes. The free station and reflector measurement modes were adopted. Among them, the total station 7 located in the left road area measured the data of the first to fifth reflector measuring points Fn,1, Fn,2, Fn,3, Fn,4, and Fn,5; the total station 7 located in the right road area measured the data of the fifth reflector measuring point Fn,5 and the sixth reflector measuring point Fn,6, so as to obtain the relative height difference and horizontal distance between the measuring points respectively.

[0060] Each monitoring cross section is independent of each other, and the measuring stations set up in different periods of the same section are also independent of each other, which greatly improves the flexibility of field instrument station setting while ensuring accuracy. This method has a short test distance, the measuring station positions only need to be roughly the same, there is no need to measure the instrument height, no need for orientation, no need for personnel to cross the road, and it is a non-contact measurement. The test can be carried out after the measuring station is set up. The measurement accuracy is high and the test speed is fast, which greatly reduces labor costs and work intensity, and personal safety is also greatly guaranteed.

[0061] During field observations, first level the instrument and aim at the fifth reflector measuring point, Fn,5. Next, tighten the horizontal and vertical brakes. Then, adjust the eyepiece and objective knobs to ensure the reflector crosshairs are clearly visible. Finally, freely set the measuring station and orientation, and click the Measure / Save button to perform the measurement. After completing the measurement / save, re-observe the target to ensure it is accurately sighted. If the instrument moves slightly, re-aim the target using the fine-motion knob and then perform the measurement / save to ensure accurate and reliable data. After completing the measurement / save at the fifth reflector measuring point, Fn,5, follow the above steps to measure and save other targets. The relative height differences between the fifth reflector measuring point Fn,5 and the other measuring points in the current monitoring cross section, i.e., Fn,5-Fn,1, Fn,5-Fn,2, Fn,5-Fn,3, Fn,5-Fn,4, Fn,5-Fn,6, are represented by ΔHFn,51, ΔHFn,52, ΔHFn,53, ΔHFn,54, and ΔHFn,56, that is:

[0062] ΔHFn,51=HFn,5-HFn,1

[0063] ΔHFn,52=HFn,5-HFn,2

[0064] ΔHFn,53=HFn,5-HFn,3

[0065] ΔHFn,54=HFn,5-HFn,4

[0066] ΔHFn,56=HFn,5-HFn,6

[0067] (3) Calculation of roadbed settlement

[0068] Since the sixth level monitoring element 6 can simultaneously measure the elevation value and the height difference between the measuring points, the sixth level measuring point Sn and the sixth reflector measuring point Fn,6 corresponding to the round nail cap on the top of the sixth level monitoring element and the reflector may not completely coincide with each other, it is assumed that the difference between the sixth level measuring point Sn of the sixth level monitoring element and the sixth reflector measuring point Fn,6 is a constant α. n , so the elevation values ​​of Fn,1, Fn,2, Fn,3, Fn,4, and Fn,5 obtained by joint calculation are not true elevations, but contain an unknown constant α n The elevation expression. Since each α n They are all fixed unknown constants and can be directly offset during the roadbed settlement calculation process. Therefore, this unknown constant is just a process quantity that does not need to be known during the roadbed settlement calculation process and will not affect the roadbed settlement calculation.

[0069] Then the relationship between the elevations of each measuring point can be expressed as follows:

[0070] HFn,5=HFSn,6+αn +ΔHFn,56

[0071] HFn,4=HFn,5-ΔHFn,54=HFn,6+α n +ΔHFn,56-ΔHFn,54

[0072] HFn,3=HFn,5-ΔHFn,53=HFn6+α n +ΔHFn,56-ΔHFn,53

[0073] HFn,2=HFn,5-ΔHFn,52=HFn,6+α n +ΔHFn,56-ΔHFn,52

[0074] HFn,1=HFn,5-ΔHFn,51=HFn,6+α n +ΔHFn,56-ΔHFn,51

[0075] In the above formula, HFn,6 is calculated by second-class precision leveling, and the relative height differences ΔHFn,51, ΔHFn,52, ΔHFn,53, ΔHFn,54, and ΔHFn,56 between the reflector measuring points are obtained by precision total station. n is a constant. Therefore, the cumulative settlement of each measuring point Fn,1, Fn,2, Fn,3, Fn,4, Fn,5 and Fn,6 can be obtained by subtracting the initial elevation value from the current elevation value.

[0076] Step 3: Roadbed convergence data

[0077] The horizontal distances between the first and second reflector points Fn,1-Fn,2, the third and fourth reflector points Fn,3-Fn,4, and the fifth and sixth reflector points Fn,5-Fn,6 are calculated using the two-point distance formula using plane coordinates measured by a precision total station. The difference between these horizontal distances and the initial horizontal distance represents the convergence of the patrol road, left-span road, and right-span road, and can be used to analyze and assess the lateral displacement stability of the roadbed.

[0078] Effect:

[0079] Fifteen days after the cement-stabilized gravel layer was filled on the left side of a highway in Tianjin, significant longitudinal cracks began to appear, particularly in the section between K17+020 and K20+295. These cracks continued to develop, and the roadbed could slip or even collapse. To quickly and accurately identify the cause of the cracks, analyze and assess the stability and usability of the roadbed, and guide the development of targeted follow-up construction plans, roadbed deformation monitoring was necessary. After 16 months of regular observation of the section, data from the K19+100 section, where cracks were more pronounced, was selected to plot a time history curve. Figure 5-Figure 7 It can be seen that:

[0080] 1) As time goes by, the roadbed sinks significantly, but the settlement at point F61,3 is significantly less than that at points F61,4, F61,5, and F61,6. This means that there is a significant differential settlement in the roadbed cross section, and this differential settlement increases over time. As of December 25, 2021, the cumulative settlements of the roadbed at points F61,3, F61,4, F61,5, and F61,6 were 18.7, 57.9, 81.6, and 70.0 mm, respectively. This means that relative to the F61,3 measuring point, the differential settlements of the cross-section roadbed reached 39.2, 62.9, and 51.3 mm, respectively.

[0081] 2) In December 2020 and August 2021, the roadbed sank sharply twice. Comparing the construction conditions, it was found that a cement-stabilized gravel layer was paved above the monitoring cross section at these two time points, and heavy-loaded vehicles passed through it frequently. This shows that there is a close positive correlation between the roadbed settlement in the early stage of roadbed filling and the dynamic and static loads above.

[0082] 3) Over time, the right-lateral convergence (the change in horizontal distance between F61,5 and F61,6) has changed little, while the left-lateral convergence (the change in horizontal distance between F61,3 and F61,4) has gradually increased, reaching 52.3 mm as of December 25, 2021. Furthermore, relative to F61,5, F61,3 is moving away from F61,5, while F61,4 is moving closer to F61,5. This indicates that there is a certain degree of "splitting" between F61,3 and F61,4, a characteristic that is largely consistent with the characteristics of roadbed cracks.

[0083] 4) Judging from the current roadbed settlement and convergence data, the roadbed deformation has not yet stabilized and monitoring needs to be strengthened during the operation period.

[0084] Similarly, by comparing and analyzing multiple monitoring data from other monitoring cross-sections during the construction period, along with crack characteristics and their timelines, we concluded that the longitudinal cracks in the roadbed were caused by significant differential settlement between the right and left road sections, i.e., significant differential settlement across the roadbed cross-section. The subsequent effective control of roadbed cracks confirms the validity of this conclusion based on the method described in this invention.

[0085] Although the preferred embodiments of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the above-mentioned specific embodiments. The above-mentioned specific embodiments are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, which all fall within the scope of protection of the present invention.

Claims

1. A platform-based highway roadbed settlement and convergence monitoring method, including: Step 1: Set up monitoring cross sections and deploy monitoring points According to the design requirements, n monitoring cross sections are set at a certain interval in the entire monitoring section, and the monitoring cross sections include at least: the right road area, the middle isolation zone area, and the left road area; Each monitoring cross section is provided with a sixth level monitoring element (6) and a plurality of reflector monitoring elements, each reflector monitoring element having the same structure; each monitoring element is accurately positioned using a GNSS receiver during installation to ensure that the measuring point on each monitoring cross section is strictly located on the designed cross section line; the sixth level monitoring element (6) includes a sixth reflector measuring point (Fn,6) and a sixth level measuring point (Sn); each reflector monitoring element has a reflector measuring point; Each area has at least one reflective sheet monitoring element; The sixth level monitoring element (6) of each monitoring cross section is located on the side slope crash wall / hard ground in the left-side road / right-side road area, and has the functions of both a settlement point and a reflector; Step 2: Simultaneously perform leveling, relative height difference, and horizontal distance measurements (1) Leveling A level is set up along the emergency lane of the left / right road area where the sixth leveling monitoring element is located according to the second-class leveling measurement specifications. The sixth leveling point of the sixth leveling monitoring element of each monitoring cross section is leveled using the level. The elevation value of the sixth leveling point of each monitoring cross section is obtained through calculation, which provides a basis for calculating the settlement of the reflector measuring point of each monitoring cross section. (2) Relative height difference and horizontal distance measurement Precision total stations are set up in the emergency lanes of the left and right sections of each monitoring cross section to obtain the height differences between the reflector measuring points. One total station is used to obtain the height difference between the sixth reflector measuring point and an adjacent reflector measuring point, and the other total station is used to obtain the height difference between the other reflector measuring points except the sixth reflector measuring point. The elevation value of each reflector measuring point in the monitoring cross section is expressed by the precise elevation of the sixth leveling measuring point of the monitoring cross section, the precise height difference between the reflector measuring points, and a fixed unknown constant between the sixth leveling measuring point and its reflector measuring points; the initial measured value is used as the initial elevation value of each reflector measuring point; Based on the plane coordinates between the measuring points of each reflector obtained by the total station in each monitoring cross section and the distance formula between the two points, the horizontal distance of the left-side road / right-side road area is calculated, and the initial measured value is used as the initial horizontal distance of the left-side road / right-side road area; (3) Calculation of roadbed settlement and roadbed convergence According to the project requirements, the measurements of (1) and (2) in step 2 are carried out at regular intervals; Subtract the initial elevation value from the elevation value of each measuring point to obtain the subgrade settlement data of all measuring points; The subtraction of the initial horizontal distance from the current horizontal distance of the left / right road area will give the roadbed convergence data of all monitored cross sections. Step 3: Determine the stability of the roadbed based on the roadbed settlement and roadbed convergence data obtained in step 2.

2. The method for monitoring the settlement and convergence of a highway roadbed according to claim 1 is characterized in that: The side slopes and median strips of the left and right road areas are provided with concrete crash barriers of a certain height.

3. The method for monitoring the settlement and convergence of a highway roadbed according to claim 1 is characterized in that: The sixth level monitoring element (6) comprises a sinking nail and a reflective sheet, the sinking nail comprising a rod portion (10) and a round nail cap (12) located at the top thereof, the rod portion (10) of the sinking nail being provided with a reflective sheet (11), the reflective sheet facing the total station; the reflective sheet of the sixth level monitoring element (6) serves as a sixth reflective sheet measuring point (Fn, 6), and the round nail cap serves as a measuring point for leveling measurement, namely, the sixth leveling measuring point (Sn).

4. The method for monitoring the settlement and convergence of a highway roadbed according to claim 1 is characterized in that: The reflector monitoring element (1, 2, 3, 4, 5) comprises a rod (10) and a reflector (11) fixed to the rod, wherein the reflector (11) faces the total station; the reflector located thereon serves as a reflector measuring point.

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