Subgrade Lateral Displacement Monitoring Method Based on Virtual Baseline

Abstract

The present invention discloses a method for monitoring the lateral displacement of a roadbed based on a virtual reference line, which includes: selecting a reference object for constructing the virtual reference line beside the roadbed to be monitored, and determining a first back sight point and a second back sight point for constructing the virtual reference line; arranging lateral displacement monitoring points on the cross-section of the roadbed to be monitored; using a total station to measure and store the first back sight point, the second back sight point and all the lateral displacement monitoring points on the cross-section, and plotting a plan view; connecting the two back sight points to form a virtual reference line, and measuring the vertical distance from the monitoring point to the virtual reference line or the horizontal distance from the monitoring point to the virtual reference line in the lateral direction of the roadbed; according to the preset monitoring frequency, regularly carrying out monitoring operations at the same measuring station, and the lateral displacement of the roadbed can be obtained by calculating the change amount of the vertical distance or the horizontal distance. A vertical displacement reference point can also be selected synchronously, and the change amount of the vertical height difference between the vertical displacement reference point and each lateral displacement monitoring point is the settlement amount of the roadbed.

Description

Technical Field

[0001] The present invention relates to engineering monitoring technology, and particularly to a method for monitoring the lateral displacement of a roadbed based on a virtual reference line. Background Art

[0002] Especially for long expressways, due to their long spans and complex and changeable terrain and geological conditions along the line, they will inevitably encounter special sections such as high slopes, soft soil subgrades, combined construction of highway and railway, and combined construction of river and road subgrades. The potential deformation risks in these sections are often relatively large, and seriously, it will cause wavy undulations on the road surface, longitudinal cracks on the road surface, and even problems such as landslides and collapses of the roadbed, which seriously affect driving safety and the safety of people's lives and property. Therefore, during the construction and operation of expressways, targeted roadbed monitoring is required for sections with relatively high risks. Roadbed monitoring often involves multiple monitoring projects simultaneously, and a very important one is the monitoring of the lateral displacement of the roadbed, which is often used to judge the lateral safety status of the roadbed. The spacing of the monitoring sections for the lateral displacement of the roadbed is often set to be different from 100m to 200m; each monitoring section often has 2 to 4 monitoring points; the monitoring frequency ranges from one week to one year; the operation period is often full-closed operation, etc. That is to say, the monitoring of the lateral displacement of the expressway roadbed often has many characteristics such as a long monitored section but a large distance between monitoring sections, few monitoring points in the section, a long monitoring interval, difficulty in connecting to the reference points, and a relatively large risk of crossing the highway. At present, the monitoring of the lateral displacement of the roadbed mainly adopts the method of combining GNSS static observation and total station traverse. This method requires a large number of working reference points to be arranged on the expressway and the known reference points to be connected through GNSS static observation. When using the total station traverse operation, multi-observation rounds must be strictly executed, otherwise the accuracy will be difficult to guarantee, which will greatly reduce the operation efficiency of this method.

[0003] Therefore, seeking a method for monitoring the lateral displacement of the roadbed with reliable accuracy and high efficiency has become a difficult problem that urgently needs to be solved by the majority of scientific and technological workers. Summary of the Invention

[0004] The purpose of the present invention is to overcome the deficiencies of the existing monitoring methods and propose a method for monitoring the lateral displacement of the roadbed based on a virtual reference line. The monitoring method is essentially a new method that constructs an accurate virtual reference line through a certain method and then calculates the lateral displacement of the roadbed based on the relative planar position relationship between the monitoring points and the virtual reference line. This method avoids the limitation that the existing method must connect to the known reference points to carry out the monitoring operation, and also avoids the requirement of the total station traverse method that multi-observation rounds must be carried out, greatly improving the operation efficiency, and the monitoring method is also applicable to the monitoring of the horizontal displacement of the foundation pit.

[0005] A method for monitoring the lateral displacement of a roadbed based on a virtual reference line includes:

[0006] Step 1: Construct the rear sight aiming area and arrange monitoring points; determine a reference object outside the range of 3 times the subgrade width on one side of the subgrade to be monitored. According to the principle that any point on a certain outer surface in the ideal state should be projected on the same straight line, set a straight line as the virtual reference line; and determine the first rear sight aiming area and the second rear sight aiming area on the plane facing the subgrade to be monitored.

[0007] Arrange multiple lateral displacement monitoring points on the cross-section of the subgrade to be monitored.

[0008] Step 2: On-site measurement and storage: Set up a precise total station at a position 20 - 50 m longitudinally from the lateral displacement monitoring points. The position where the central axis of the total station is located is used as the measuring station; in the free stationing prism-free / reflection sheet mode, sequentially measure and store any measuring points in the first rear sight aiming area, any measuring points in the second rear sight aiming area, and all lateral displacement monitoring points on the monitoring cross-section, and measure and store the position data.

[0009] According to the measured position data, use mapping software to draw the plan views of the measuring points in the first rear sight aiming area, the measuring points in the second rear sight aiming area, and all lateral displacement monitoring points; connect the measuring points in the first rear sight aiming area and the measuring points in the second rear sight aiming area to form the virtual reference line.

[0010] Use mapping software to draw perpendicular lines from each lateral displacement monitoring point to the virtual reference line. The foot of the perpendicular is the corresponding virtual reference point, and the perpendicular distance from each lateral displacement monitoring point to the virtual reference line is obtained through the distance measurement function.

[0011] Step 3: According to the preset monitoring frequency, execute Step 2 at the same measuring station to obtain the perpendicular distances of each lateral displacement monitoring point. The difference between the current perpendicular distance and the initial perpendicular distance can obtain the change amount of the perpendicular distance. Since the change amount of the perpendicular distance is the projection of the lateral displacement of the subgrade on the perpendicular line from the lateral displacement monitoring point to the virtual reference line, therefore, the lateral displacement of the subgrade at each monitoring point can be deduced through the trigonometric function relationship between the change amount of the perpendicular distance and the lateral displacement of the subgrade. Among them, the included angle between the perpendicular line from the lateral displacement monitoring point to the virtual reference line and the subgrade side line in the trigonometric function relationship is a constant, which can be obtained through tools such as angle measuring tools.

[0012] Furthermore, to improve the reliability of the initial perpendicular distance, Step 2 further includes: independently measure the perpendicular distances from each lateral displacement monitoring point to the virtual reference line multiple times, and take the average value of the perpendicular distances measured independently multiple times as the initial perpendicular distance.

[0013] Optionally, Step 2 and Step 3 include the following steps:

[0014] Step 2: On-site measurement and storage: Set up a precise total station at a position 20 - 50 m longitudinally away from the transverse displacement monitoring point. The position where the central axis of the total station is located serves as the measurement station. Use the free stationing prismless / reflection sheet mode to sequentially measure and store any measurement points in the first rear sight alignment area, any measurement points in the second rear sight alignment area, and all transverse displacement monitoring points on the monitoring cross-section, and measure and store the position data.

[0015] Based on the measured and stored position data, use mapping software to draw a plan view of the measurement points in the first rear sight alignment area, the measurement points in the second rear sight alignment area, and all transverse displacement monitoring points. Connect the measurement points in the first rear sight alignment area and the measurement points in the second rear sight alignment area to form a dotted reference line.

[0016] The connection direction between any two monitoring points within the cross-section can be regarded as the roadbed transverse displacement direction, and the intersection point of the connection line between any two monitoring points within the cross-section and the virtual reference line is the virtual reference point. The horizontal distance from the monitoring point to the virtual reference point can be obtained through the distance measurement function of the mapping software.

[0017] Step 3: According to the preset monitoring frequency, execute Step 2 at the same measurement station to obtain the horizontal distance from the current monitoring point to the virtual reference point. The change amount between the current horizontal distance and the initial horizontal distance is the change amount of the roadbed transverse displacement.

[0018] Furthermore, Step 2 further includes: Independently measure the horizontal distance from the monitoring point to the virtual reference point multiple times, and take the average value of the horizontal distances measured independently multiple times as the initial horizontal distance.

[0019] Preferably, the method for monitoring the roadbed transverse displacement based on the virtual reference line includes:

[0020] Step 1: Construct the rear sight alignment area. Manually arrange 2 observation piers as reference objects outside the range of 3 times the roadbed width of the downhill slope angle of the roadbed slope on the extension line of the monitoring cross-section. The distance between the observation piers is 20 - 50 m. The first rear sight alignment area and the second rear sight alignment area are respectively located on one observation pier, and the two rear sight alignment areas are arranged facing the measurement station. To improve the accuracy and consistency of the virtual reference line, the connection line between the two observation piers is as perpendicular as possible to the monitoring cross-section line to improve the graphic shape. Install a reflection sheet on each observation pier. The above two reflection sheets are the first and second rear sight alignment areas of the method. Through the collimation line method of the precise total station, make the reflection sheets as much as possible in the same vertical plane to weaken the influence of the collimation error, and at the same time, the reflection intensity of the collimation signal can also be improved.

[0021] Step 2: Arrange the monitoring points. Use GNSS to accurately lay out and arrange the transverse displacement monitoring points on the monitoring cross-section. To improve the accuracy of the monitoring data and avoid personnel crossing the road, the monitoring points should preferably be in the reflection sheet mode, and through the collimation line method of the total station, ensure that the reflection sheets of the monitoring points are as much as possible in the same vertical plane.

[0022] Step 3: On-site measurement and storage. Set up a total station at a position about 30 m longitudinally from the subgrade of the monitoring cross-section. In the free stationing prismless / reflection sheet mode, successively measure and store any measuring points in the first rear sight alignment area, any measuring points in the second rear sight alignment area, and all transverse displacement monitoring points on the cross-section.

[0023] Step 4: Plotting and processing of measuring points. The measured and stored data can obtain the plane views of the measuring points in the first rear sight alignment area, the measuring points in the second rear sight alignment area, and the transverse displacement monitoring points on the cross-section through the point plotting tool of the mapping software; a virtual reference line can be constructed through the measuring points in the first rear sight alignment area and the measuring points in the second rear sight alignment area; draw perpendicular lines from each transverse displacement monitoring point to the virtual reference line through the mapping software, and the foot of the perpendicular is the corresponding virtual reference point. The perpendicular distance from each transverse displacement monitoring point to the virtual reference line can be obtained through the distance measurement function; to improve the reliability of the initial perpendicular distance, take the average value of the perpendicular distances deduced from 3 independent measurements as the initial value.

[0024] Step 5: According to the preset monitoring frequency, repeat Steps 3 and 4 to obtain the change amount of the perpendicular distance of each transverse displacement monitoring point. Since the change amount of the perpendicular distance is the projection of the subgrade transverse displacement on the perpendicular line from the transverse displacement monitoring point to the virtual reference line, therefore, the subgrade transverse displacement of each monitoring point can be deduced through the trigonometric function relationship between the change amount of the perpendicular distance and the subgrade transverse displacement.

[0025] When the reference object is two artificially buried observation piers, this situation is for the case where there are no stable and regular buildings outside the range of 3 times the subgrade width at the lower slope foot of the subgrade to be monitored. Then its alternative can also be 2 stably arranged reflection sheets. The reflection sheets should be arranged in the same vertical plane as much as possible through the total station sighting line method. The virtual reference point should be located between the two reflection sheets, and the reflection sheets face the measuring station.

[0026] Optionally, the following method is adopted to construct the rear sight alignment area in Step 1:

[0027] Assume that there is a stable and regular building outside the range of 3 times the subgrade width at the lower slope foot of the subgrade to be monitored, and in the ideal state, any point on an outer facade facing the subgrade to be monitored should be projected on the same straight line, that is, the virtual reference line of the method; in order to improve the consistency of the virtual reference line as much as possible, a 5 cm * 5 cm approximate sighting area should be selected at the left and right ends of an outer facade of the building as the rear sight alignment area respectively. The sighting areas should be at approximately the same height to weaken the error caused by the inclination of the building.

[0028] Optionally, Steps 3 to 5 include the following steps:

[0029] Step 3: On-site measurement and storage. Set up a total station about 30 m longitudinally from the subgrade of the monitoring cross-section. In the free stationing prism-free / reflection sheet mode, measure and store any measuring points in the first rear sight aiming area, any measuring points in the second rear sight aiming area, and all transverse displacement monitoring points on the cross-section in sequence.

[0030] Step 4: Plotting and processing of measuring points. The measured and stored data can obtain the plane views of the measuring points in the first rear sight aiming area, the measuring points in the second rear sight aiming area, and the transverse displacement monitoring points on the cross-section through the point plotting tool of the mapping software; a virtual reference line can be constructed through the measuring points in the first rear sight aiming area and the measuring points in the second rear sight aiming area; the connecting line direction between any two monitoring points in the cross-section can be regarded as the transverse displacement direction of the subgrade, and the intersection of the connecting line between any two monitoring points in the cross-section and the virtual reference line is the virtual reference point; the horizontal distance from the monitoring point to the virtual reference point can be obtained through the distance measurement function. In order to improve the reliability of the initial horizontal distance, generally, the average value of 3 independent horizontal distances is taken as the initial value.

[0031] Step 5: According to the preset monitoring frequency, repeat Step 3 and Step 4 to obtain the horizontal distance from the current monitoring point to the virtual reference point. The change amount between the current horizontal distance and the initial horizontal distance is the transverse displacement of the subgrade.

[0032] Preferably, the reference object is a stable building structure, and the first rear sight aiming area and the second rear sight aiming area are at the same height.

[0033] Particularly preferably, reflection sheets are pasted at the positions of the first rear sight aiming area and the second rear sight aiming area to improve the consistency of the virtual reference line.

[0034] Preferably, the transverse displacement monitoring points are staked out and positioned by using GNSS satellites, and the monitoring points are stably arranged on the road surface in the reflection sheet mode.

[0035] Furthermore, according to the method for monitoring the transverse displacement of the subgrade based on the virtual reference line, select a certain characteristic point on the building structure as the reference point for vertical displacement. In Step 3, synchronously obtain the vertical height difference between this reference point and each monitoring point. In Step 5, the change amount between the current vertical height difference and the initial vertical height difference can be regarded as the vertical displacement of the subgrade.

[0036] Preferably, the reference point for vertical displacement should be any measuring point on the first rear sight aiming area or the second rear sight aiming area.

[0037] Optionally, the reference point for vertical displacement can be a certain characteristic point on the building structure.

[0038] Compared with the prior art, the beneficial effects brought by the technical solution of the present invention are:

[0039] 1. Compared with conventional GNSS static observation methods, traverse methods, etc., all conventional methods require the accurate coordinates of known reference points to calculate the coordinates of monitoring points. However, for the monitoring method described in the present invention, there are no special requirements for the reference points and their coordinates. As long as the on-site to be measured meets the conditions for constructing a virtual reference line, it is sufficient. In addition, when implementing this method, each monitoring cross-section can be independently measured using the free stationing prismless / reflection sheet mode, which can effectively avoid errors such as back sighting alignment error, cumulative error, and instrument height error, greatly improving the operation accuracy, operation efficiency, and on-site operability of this method, and having strong practicality.

[0040] 2. This method synchronously solves many problems such as difficult connection measurement of reference points, poor lateral visibility conditions, not allowing to cross roads, low operation efficiency, etc. At the same time, under certain conditions, it can also be used for vertical displacement monitoring synchronously, and can also be directly promoted and applied to the monitoring scenarios of horizontal and vertical displacements of foundation pits in municipal engineering, etc., having strong universality. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 is a monitoring schematic diagram using the monitoring method described in the present invention;

[0042] Figure 2 is a top view plan obtained using CAD software in Example 1;

[0043] Figure 3 is a schematic diagram of the perpendicular line and foot of the perpendicular from the lateral displacement monitoring point to the virtual reference line in Example 1;

[0044] Figure 4 is a schematic diagram showing the change amount of the monitoring point in Example 1;

[0045] Figure 5 is a monitoring schematic diagram of the monitoring method described in Example 2;

[0046] Figure 6 is a top view plan obtained using CAD software in Example 2;

[0047] Figure 7 is a schematic diagram of the perpendicular line and foot of the perpendicular from the lateral displacement monitoring point to the virtual reference line in Example 2;

[0048] Figure 8 is a schematic diagram showing the change amount of the monitoring point in Example 2;

[0049] Figure 9 is to obtain the length values of line segments XN - P1 and XN - P2 in Example 3.

[0050] Among them,

[0051] HS1: The first back sight point, any measuring point in the first back sighting area; HS2: The second back sight point, the second back sight

[0052] Any measuring point in the quasi-region;

[0053] XN: Virtual reference point; P1: First monitoring point;

[0054] P2: Second monitoring point; P3: Third monitoring point; CZ: Measuring station;

[0055] XN1: First virtual reference point; XN2: Second virtual reference point; XN3: Third virtual reference point. Specific implementation manners

[0056] The technical solutions of the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. The specific embodiments described are only for explaining the present invention and are not intended to limit the present invention. The method is applicable not only to scenarios with good lateral visibility conditions, but also to scenarios with poor lateral visibility conditions, such as fully enclosed, high slopes, large retaining walls, etc., where the cross-section spacing is far and the joint measurement of reference points is difficult.

[0057] Embodiment 1

[0058] As Figure 1 shown, a method for monitoring the lateral displacement of a roadbed based on a virtual reference line is applied to the monitoring of the lateral displacement of a highway roadbed. A monitoring cross-section is set every 200 meters along the longitudinal direction of the roadbed. There are 3 monitoring points for the lateral displacement of the roadbed in each cross-section, and each cross-section independently executes the monitoring method to monitor the lateral displacement of the roadbed. The specific steps are as follows:

[0059] Step 1: Construct a back sight alignment area and monitoring points

[0060] S11: Figure 1 Artificially arrange 2 stable observation piers outside the range of 3 times the roadbed width of the downhill slope angle of the roadbed slope in the extension line of the monitoring cross-section in the upper middle part. The distance between the observation piers is 20 - 50m. To improve the accuracy and consistency of the virtual reference line, the connection line between the two observation piers is as perpendicular as possible to the monitoring cross-section line to improve the graphic shape. Reflective sheets are arranged on the observation piers, and the reflective sheets are made to be as much as possible in the same vertical plane through the collimation line method of the total station to weaken the influence of the collimation error. At the same time, the collimation consistency and signal reflection intensity can also be improved thereby. The above two reflective sheets are the first and second back sight alignment areas of the method, and the measuring points are the first back sight point HS1 and the second back sight point HS2 as Figure 1 shown.

[0061] S12: According to the monitoring design scheme, use GNSS satellites for precise lofting, and arrange stable reflective sheets as monitoring points. As Figure 1 shown, a total of the first monitoring point P1, the second monitoring point P2, and the third monitoring point P3 are arranged; the monitoring points are stably arranged on the highway pavement in the form of reflective sheets, and are respectively arranged on the left and right slope sides and the central isolation belt of the highway.

[0062] Step 2: On-site measurement and storage and plotting of measurement points

[0063] S21: Set up a precision total station on the slope about 30 meters longitudinally away from the monitoring cross-section. The position where the central axis of the precision total station is located is used as the measurement station CZ. In the free stationing and prismless / reflection sheet mode, successively aim at the first external back sight point HS1, the second back sight point HS2, the first monitoring point P1, the second monitoring point P2, and the third monitoring point P3, and measure and store their relative positions.

[0064] S22: Use CAD software to plot the first back sight point HS1, the second back sight point HS2, the first monitoring point P1, the second monitoring point P2, and the third monitoring point P3 to obtain the plane distribution map as shown in Figure 2 Figure; Connect the measurement points HS1 in the first back sight aiming area and the measurement points HS2 in the second back sight aiming area to form a virtual reference line HS1 - HS2;

[0065] Draw perpendicular lines from each horizontal displacement monitoring point to the virtual reference line HS1 - HS2 through the mapping software. The foot of the perpendicular is the corresponding virtual reference point. Through the distance measurement function, the perpendicular distance from each horizontal displacement monitoring point to the virtual reference line can be obtained. As shown in Figure 3 Figure, P1 - XN1, P2 - XN2, and P3 - XN3 are the perpendicular distances from the horizontal displacement monitoring points P1, P2, and P3 to the virtual reference line respectively. To improve the reliability of the initial perpendicular distance, the average value of the perpendicular distances deduced after 3 independent measurements is taken as the initial value.

[0066] Step 3: Regular monitoring

[0067] According to the preset monitoring frequency, execute the content of steps S21 and S22, and the change amount of the perpendicular distance of each horizontal displacement monitoring point can be obtained. Since the change amount of the perpendicular distance is the projection of the subgrade horizontal displacement on the perpendicular line from the horizontal displacement monitoring point to the virtual reference line, therefore, through the trigonometric function relationship between the change amount of the perpendicular distance and the subgrade horizontal displacement, the subgrade horizontal displacement of each monitoring point can be deduced.

[0068] Refer to Figure 4 , since the change amount of the perpendicular distance Δh is the projection of the subgrade horizontal displacement Δs on the perpendicular line, therefore:

[0069] Δs = Δh / sinα

[0070] Among them, Δs represents the change amount of the subgrade horizontal displacement, Δh represents the change amount of the perpendicular distance from the current monitoring point to the virtual reference line, and α is the included angle between the monitoring cross-section line and the subgrade side line.

[0071] According to the above steps, the subgrade horizontal displacement of each monitoring point can be deduced.

[0072] Example 2

[0073] A method for monitoring the lateral displacement of subgrade based on a virtual reference line. The monitoring method is similar to that in Embodiment 1, except for Step 1. The remaining steps are the same as those in Embodiment 1 and will not be elaborated here.

[0074] Step 1: Set up backsight points and monitoring points

[0075] In this embodiment, there are stable and regular structures outside the lower slope toe of the subgrade slope to be monitored, at a distance of 3 times the subgrade width. Figure 5 The upper-middle gray cuboid is the stable structure outside the subgrade. Assume that there is a regular outer facade on the side of the structure facing the subgrade, that is, in an ideal state, the projections of any points on its outer facade should be on the same straight line. Assume that the first backsight point HS1 and the second backsight point HS2 (i.e., any measurement points in the first backsight alignment area and the second backsight alignment area) are two points with unknown coordinates at the left and right ends on the outer facade. Through these two points, a virtual reference line can be constructed. To improve the consistency of the virtual reference line, the two backsight points should be at the same height and located at the left and right ends of the structure facade respectively, and reflective sheets should be pasted in the first and second backsight alignment areas. At the same time, the virtual reference point P should be located between the projection lines of the first backsight point HS1 and the second backsight point HS2.

[0076] Figures 6 - 8 The plan view plotted using mapping software is shown, as well as the connection between the monitoring points and the virtual reference line on the plan view.

[0077] Embodiment 3

[0078] A method for monitoring the horizontal displacement of foundation pit based on a virtual reference line. The monitoring method is basically the same as that in Embodiment 1.

[0079] On the plane distribution map obtained by plotting the first backsight point HS1, the second backsight point HS2, the first monitoring point P1, the second monitoring point P2, and the third monitoring point P3 using CAD software, extend the line P1 - P2 towards the structure and make it intersect with the line HS1 - HS2, then the virtual reference point XN can be obtained. Where the line P1 - P2 is the connection line between the first monitoring point P1 and the second monitoring point P2, and the line HS1 - HS2 is the connection line between the first backsight point HS1 and the second backsight point HS2.

[0080] Use the distance measurement function of CAD software to obtain the horizontal distance from the virtual reference point XN to the first monitoring point P1 (the length of the line segment XN1 - P1), and the horizontal distance from the virtual reference point XN to the second monitoring point P2 (the length of the line segment XN - P2). Figure 9 The measured data is shown. Similarly, for the P3 point, the horizontal distance from the P3 point to the virtual reference line in the lateral direction of the subgrade can also be obtained by the above method. To improve the reliability of the initial horizontal distance, generally, the average value of 3 independent horizontal distances is taken as the value of the initial horizontal distance.

[0081] According to the preset monitoring frequency, execute the content of steps S21 and S22. At the same survey station CZ, use a precise total station to measure the first back sight point HS1, the second back sight point HS2, the first monitoring point P1, the second monitoring point P2, and the third monitoring point P3, and use CAD software to obtain the horizontal distances of the current line segments XN-P1, XN-P2, and XN-P3. By subtracting the current horizontal distances of XN-P1, XN-P2, and XN-P3 from the initial horizontal distances obtained in step two, the lateral displacement of the subgrade can be obtained.

[0082] Since the main direction of the horizontal displacement of the foundation pit is fixed, if displacement occurs, it is perpendicular to the retaining structure of the foundation pit. In this embodiment, the set monitoring points are located at the top of the piles / walls of the foundation pit support structure in the form of reflectors. Then, reasonably select two back sight points outside 3 times the excavation depth of the foundation pit, and the horizontal displacement of the top of the piles / walls of the foundation pit support structure can be obtained according to the method described in Embodiment 1.

[0083] Embodiment 4

[0084] A method for monitoring the vertical displacement of a subgrade. Based on Embodiment 1, use the reflector measuring point in one of the back sight aiming areas as the reference point for vertical displacement. For example, use the first back sight point HS1 (reflector measuring point) as the reference point, and synchronously obtain the vertical height differences between the first back sight point HS1 (reflector measuring point) and each monitoring point in the method of Embodiment 1. The change amount between the current vertical height difference and the initial vertical height difference is the vertical displacement of the subgrade. To improve the measurement accuracy, the second back sight point HS2 (reflector measuring point) can be used as a check point.

[0085] Although the preferred embodiments of the present invention are described above in conjunction with the accompanying drawings, the present invention is not limited to the above specific embodiments. The above specific embodiments are merely illustrative and not restrictive. Under the inspiration of the present invention, other technical personnel in the art can also make other forms without departing from the purpose of the present invention and the scope protected by the claims. All of these fall within the protection scope of the present invention.

Claims

1. A method for monitoring the lateral displacement of a roadbed based on a virtual reference line, characterized in that, Including: Step 1: Construct the rear view sighting area and arrange monitoring points: Manually arrange reference objects outside the lower slope foot of the subgrade slope to be monitored by 3 times the subgrade width, and determine the first rear view sighting area and the second rear view sighting area on the plane of the reference object facing the subgrade to be monitored; the reference object is a stable building structure, the first rear view sighting area and the second rear view sighting area are at the same height and are located in a certain outer facade of the building structure facing the measuring station, and reflector sheets are pasted at the positions of the first rear view sighting area and the second rear view sighting area; Arrange multiple transverse displacement monitoring points on the cross-section of the subgrade to be monitored; Step 2: On-site measurement and storage: Set up a precise total station at a position 30 m longitudinally from the transverse displacement monitoring point, and the position where the central axis of the total station is located is used as the measuring station (CZ); Use the free stationing prismless / reflection sheet mode to measure and store any measuring point (HS1) of the first rear view sighting area, any measuring point (HS2) of the second rear view sighting area, and all transverse displacement monitoring points on the cross-section in sequence, and measure and store the position data; According to the measured and stored position data, use mapping software to draw the plan views of the measuring points (HS1) of the first rear view sighting area, the measuring points (HS2) of the second rear view sighting area, and all transverse displacement monitoring points; Connect the measuring points of the first rear view sighting area and the measuring points of the second rear view sighting area to form a dotted reference line; The connecting direction of any two monitoring points within the cross-section is regarded as the transverse displacement direction of the subgrade, and the intersection point of the connecting line of any two monitoring points within the cross-section and the virtual reference line is the virtual reference point; Obtain the horizontal distance from the monitoring point to the virtual reference point through the distance measurement function; Among them, take the average value of 3 independent horizontal distances as the initial value; Step 3: According to the preset monitoring frequency, repeat Step 2 at the same measuring station (CZ) to obtain the horizontal distance from the current monitoring point to the virtual reference line in the transverse direction of the subgrade, and the change amount between the current horizontal distance and the initial horizontal distance is the transverse displacement of the subgrade.

2. The method for monitoring the lateral displacement of a roadbed based on a virtual reference line according to claim 1, wherein The reference object is two manually arranged reflector sheets, the first rear view sighting area and the second rear view sighting area are respectively located on one reflector sheet and the two rear view sighting areas are arranged facing the measuring station, and the virtual reference point is located between the two rear view sighting areas.

3. The method for monitoring the lateral displacement of a roadbed based on a virtual reference line according to claim 1, wherein, The transverse displacement monitoring points are accurately laid out using GNSS satellites. The transverse displacement monitoring points are arranged on the road surface in the reflection sheet mode, and the reflector sheets are arranged in the same vertical plane by the total station collimation method.

4. The method for monitoring the lateral displacement of the roadbed based on the virtual reference line according to claim 1, wherein, Select any characteristic point on the building structure as the vertical displacement reference point, synchronously obtain the vertical height differences between the vertical displacement reference point and each transverse displacement monitoring point in Step 2, and the change amount between the current vertical height difference and the initial vertical height difference in Step 3 is the settlement amount of the subgrade monitoring.

5. The method for monitoring the lateral displacement of a roadbed based on a virtual reference line according to claim 4, characterized in that, The reference point of the vertical displacement is any reflector sheet measuring point on the first rear view sighting area or the second rear view sighting area.

6. The method for monitoring the lateral displacement of the roadbed based on the virtual reference line according to claim 1, wherein, The monitoring method is applicable to the transverse or vertical displacement monitoring of highway subgrades or foundation pits.

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