Method for calibrating a measuring device for laying a fully floating gravel bed

Abstract

The present application relates to a kind of for full floating gravel base laying surveying equipment calibration method, surveying equipment includes riprap pipe GPS and echo sounder, riprap pipe GPS is installed on the top of riprap pipe, echo sounder is installed on the upper end of riprap pipe;Riprap pipe bottom is equipped with oil cylinder, and the telescopic shaft of oil cylinder is connected with echo sounder reflector;The calibration method includes the following steps: layout control network: at least three control points are selected on the shore and layout control network, and total station is installed in any position in control network;The riprap pipe bottom is measured using total station, riprap pipe GPS respectively, and the measurement results of two are compared, to calibrate the measurement accuracy of riprap pipe GPS once;The distance of echo sounder to echo sounder reflector is measured and the measurement result is compared with the actual telescopic amount of oil cylinder, to calibrate the measurement accuracy of echo sounder.The calibration method calibrates the measurement accuracy of surveying equipment, to improve the accuracy of measurement result, avoid the construction error caused by the accuracy of surveying equipment.

Description

Technical Field

[0001] This invention belongs to the field of immersed tunnel technology, and in particular relates to a verification method for a measuring device for laying a fully floating gravel bed. Background Technology

[0002] In the construction of subsea tunnels, a layer of crushed stone needs to be laid in the excavated foundation trench before the immersed tube is installed to improve the bearing capacity of the foundation. This ensures that the load from the upper immersed tube is evenly distributed to the foundation to meet the requirements of deformation and stability. It also makes full use of the permeability of the crushed stone foundation to reduce the water level difference before and after the structure, avoid seepage, and protect the foundation from the erosion of waves and water flow. Therefore, the laying of the crushed stone foundation is a common and key process in the construction of subsea tunnels, which has a great impact on the quality and progress of the entire project.

[0003] Since crushed stone subgrade laying is an underwater construction process, most existing technologies utilize stone-throwing pipes to deliver crushed stone from the water surface. These pipes are typically installed on leveling boats floating on the water. By installing GPS positioning equipment on top of the pipes, the elevation of the bottom of the pipes is calculated based on their length, thus determining the laying height of the crushed stone subgrade. The laying position of the crushed stone subgrade is then calculated from the position of the pipes. However, GPS itself has low accuracy and is susceptible to ionospheric interference, frequently experiencing signal loss, leading to inaccurate measurement results, delays in construction progress, and impacts on construction quality. Currently, crushed stone subgrade laying relies solely on GPS measurements, without other reference methods. Therefore, when GPS measurement errors occur, construction personnel struggle to detect them promptly, resulting in poor laying quality, large construction errors, and even potential rework. Existing measuring equipment is not only detrimental to crushed stone subgrade laying but also increases construction costs and prolongs the construction period. Summary of the Invention

[0004] To address the shortcomings of related technologies, this invention provides a calibration method for a measuring device used in laying a fully floating gravel bed, which verifies the measurement accuracy of the measuring device, improves the accuracy of the measurement results, avoids construction errors caused by the measurement accuracy of the measuring device, and thus improves the construction quality.

[0005] This invention provides a verification method for a measuring device used in laying a fully floating gravel bed. The gravel bed is laid using a fully floating leveling vessel and a rock-casting pipe. The measuring device includes a rock-casting pipe GPS and a sonar. The rock-casting pipe GPS is used to measure the laying position and elevation of the gravel bed, and is installed at the top of the rock-casting pipe. A hydraulic cylinder for adjusting the length of the rock-casting pipe is installed at the bottom of the rock-casting pipe, and the sonar is used to measure the extension of the hydraulic cylinder. The sonar is installed on both sides of the rock-casting pipe, and the hydraulic cylinder extends and retracts vertically, with the extension shaft of the hydraulic cylinder connected to a sonar reflector. The verification method includes the following steps:

[0006] Establish a control network: Select at least three control points on the shore to establish a control network, and install a total station at any location in the control network;

[0007] GPS initial calibration of the rock-laying pipe: Before rock-laying, a total station is used to measure the rock-laying pipe using a bottom prism installed at the bottom of the pipe. The bottom of the rock-laying pipe is measured using both the total station and the GPS of the rock-laying pipe, and the results are compared to verify the measurement accuracy of the GPS. If the difference between the two measurement results is within the allowable range, the measurement accuracy of the GPS meets the construction requirements; if the difference exceeds the allowable range, the GPS of the rock-laying pipe does not meet the construction requirements.

[0008] Sonar calibration: Before throwing rocks through the rock-throwing pipe, the distance from the sonar to the sonar reflector is measured and the measurement result is compared with the actual extension and retraction of the hydraulic cylinder to determine whether the sonar meets the construction requirements. When the difference between the extension and retraction of the hydraulic cylinder and the sonar detection distance is within the allowable range, the sonar meets the construction requirements. When the difference between the extension and retraction of the hydraulic cylinder and the sonar detection distance exceeds the allowable range, the sonar does not meet the construction requirements.

[0009] This technical solution verifies the accuracy of the GPS of the rock-throwing pipe by setting up a control network and using a total station and bottom prism to measure the bottom of the rock-throwing pipe; and verifies the sonar measurement results by actually measuring the extension and retraction of the hydraulic cylinder.

[0010] In some of these embodiments, the control points are selected from data provided by the local mapping bureau.

[0011] In some embodiments, during the initial GPS calibration step of the slinger, the slinger needs to be installed on the leveling boat first, and the initial GPS calibration of the slinger is performed after the leveling boat is leveled.

[0012] This technical solution involves performing a GPS calibration of the riprap tube after leveling the leveling vessel to prevent measurement errors caused by the leveling vessel tilting.

[0013] In some embodiments, the leveling vessel is equipped with legs around its perimeter, and the leveling vessel is leveled by raising and lowering the legs.

[0014] In some embodiments, during the initial GPS verification step of the rock-drop pipe, the total station and the rock-drop pipe GPS measure the planar position coordinates and elevation of the bottom of the rock-drop pipe; if the difference in planar position is within 3cm and the difference in elevation is within 4cm, it meets the construction requirements.

[0015] In some embodiments, during the GPS calibration step of the riprap tube, the total station performs four rounds of observations of the bottom of the riprap tube to reduce measurement errors.

[0016] In some embodiments, the verification method further includes a secondary verification of the riprap GPS. During the laying of the crushed stone base, the total station calculates the laying height of the crushed stone base using a top prism installed on the top of the riprap. The laying height of the crushed stone base measured by the total station is compared with the laying height of the crushed stone base measured by the riprap GPS to verify the measurement accuracy of the riprap GPS. When the difference between the two measurement results is within the allowable range, the measurement accuracy of the riprap GPS meets the construction requirements. When the difference between the two measurement results exceeds the allowable range, the riprap GPS does not meet the construction requirements.

[0017] In some embodiments, before the rock-throwing pipe GPS is calibrated, a rock-throwing pipe GPS and a top prism are installed at the top of the rock-throwing pipe, and a bottom prism is installed at the bottom of the rock-throwing pipe.

[0018] In some embodiments, after the GPS calibration step of the rock-throwing tube is completed, the bottom prism at the bottom of the rock-throwing tube is removed.

[0019] This technical solution involves removing the bottom prism after the GPS of the stone-throwing tube has completed a calibration, in order to prevent damage to the bottom prism during stone-throwing.

[0020] Based on the above technical solution, the calibration method for the measuring equipment used in the fully floating gravel bed laying embodiment of the present invention can calibrate the measurement accuracy of the measuring equipment, making the measurement results more accurate, avoiding construction errors caused by the accuracy of the measuring equipment, and the calibration method is simple and easy to operate. Attached Figure Description

[0021] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings:

[0022] Figure 1 This is a schematic diagram of the structure of a verification method for a fully floating gravel bed laying measurement device according to an embodiment of the present invention, after the sonar and sonar reflector plate are installed on the stone-throwing pipe.

[0023] In the picture:

[0024] 1. Rock-throwing tube; 2. Sonar; 3. Sonar reflector. Detailed Implementation

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0026] In the description of this invention, it should be understood that the terms "center", "lateral", "longitudinal", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0027] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0028] The crushed stone foundation is laid using a fully floating leveling vessel and a stone-laying pipe 1. In existing technology, a stone-laying pipe GPS is installed at the top of the stone-laying pipe 1 to measure the laying position and elevation of the crushed stone foundation. A hydraulic cylinder is installed at the bottom of the stone-laying pipe 1 to adjust its length. The hydraulic cylinder extends and retracts vertically. Since the laying of the crushed stone foundation is an underwater construction, the hydraulic cylinder is affected by seawater during underwater operation, making it impossible to determine the extension and retraction amount by controlling the oil volume. By installing a sonar 2 on the stone-laying pipe 1 and connecting a sonar reflector 3 to the extension and retraction shaft of the hydraulic cylinder, the extension of the hydraulic cylinder can be accurately measured using the cooperation of sonar 2 and sonar reflector 3. Due to the complex underwater environment, the measurement accuracy of the stone-laying pipe GPS and sonar 2 is easily affected by other factors. Relying solely on the stone-laying pipe GPS and sonar 2 for measurement cannot verify and check the measurement results. Therefore, when errors occur in the measurement of the stone-laying pipe GPS and sonar 2, the construction personnel cannot be notified in a timely manner.

[0029] In an illustrative embodiment of the calibration method for the measuring equipment used in the laying of a fully floating gravel bed according to the present invention, the measuring equipment includes a rock-throwing pipe GPS and a sonar 2. The calibration method for the measuring equipment used in the laying of a fully floating gravel bed includes the following steps:

[0030] Establishing a control network: Select at least three control points on the shore where the leveling vessel is moored to establish a control network, and install a total station at any location within the control network. It should be noted that the control point data is provided by the local surveying and mapping bureau. The local surveying and mapping bureau provides a large number of control points, and this data is only the original source of the control point data. The control points used to establish the control network are selected from the data provided by the local surveying and mapping bureau, with at least three suitable control points chosen. It should also be noted that the selection of control points is a conventional technique in this field and will not be elaborated upon here.

[0031] Initial GPS calibration of the rock-laying pipe: Before rock-laying begins, a bottom prism is installed at the bottom of rock-laying pipe 1. A total station is used to measure the bottom of rock-laying pipe 1 using the bottom prism. The bottom of rock-laying pipe 1 is measured using both the total station and the GPS, and the results are compared to calibrate the GPS's accuracy. This checks whether the GPS's accuracy meets the construction requirements. If the difference between the two measurements is within the allowable range, the GPS's accuracy meets the construction requirements. If the difference exceeds the allowable range, the GPS does not meet the construction requirements. It should be noted that before the initial GPS calibration, rock-laying pipe 1 needs to be installed on the leveling boat, and... After the leveling vessel is leveled, the GPS of the rock-drop tube is calibrated again to avoid large measurement errors of the total station and the GPS of the rock-drop tube due to the tilt of the leveling vessel. The leveling vessel is equipped with pile legs on all four sides. By raising and lowering the pile legs, the leveling vessel is leveled as a whole. It should also be noted that the leveling vessel is still moored on the shore when the GPS of the rock-drop tube is calibrated. If the GPS of the rock-drop tube does not meet the construction requirements, it can be replaced in time. In addition, it should be noted that the total station and the GPS of the rock-drop tube measure the plane position coordinates and elevation of the bottom of the rock-drop tube 1. If the difference between the plane position measured by the total station and the GPS of the rock-drop tube is within 3cm and the difference between the elevation is within 4cm, then the measurement accuracy of the GPS of the rock-drop tube meets the construction requirements.

[0032] Sonar calibration: Before throwing rocks from the rock-throwing pipe 1, the distance from sonar 2 to sonar reflector 3 is measured, and the measurement result is compared with the actual extension and retraction of the hydraulic cylinder to determine whether the measurement accuracy of sonar 2 meets the construction requirements. When the difference between the hydraulic cylinder extension and retraction and the detection distance of sonar 2 is within the allowable range, the measurement accuracy of sonar 2 meets the construction requirements; when the difference exceeds the allowable range, the measurement accuracy of sonar 2 does not meet the construction requirements. It should be noted that during the sonar calibration step, the leveling vessel remains moored at the shore. If sonar 2 does not meet the construction requirements, it can be replaced in a timely manner. It should also be noted that the range of the difference between the hydraulic cylinder extension and retraction and the detection distance of sonar 2 needs to be selected based on the actual construction conditions and seawater current velocity, etc. In addition, it should be noted that if... Figure 1 As shown, two sets of sonars 2 are symmetrically arranged on the outer periphery of the rock-throwing pipe 1, and two sonar reflectors 3 are symmetrically arranged on the telescopic shaft of the hydraulic cylinder. The two sonar reflectors 3 are arranged in a one-to-one correspondence with the two sets of sonars 2. Each set of sonars 2 includes two sonars 2, and the two sonars 2 in the same set share a sonar 2 transmitting plate. By setting two sets of sonars 2, the accuracy of sonar measurement results can be improved.

[0033] To increase the measurement accuracy of the total station and the rock-drop GPS, in the first calibration step of the rock-drop GPS, the total station performs four rounds of observations on the bottom of rock-drop tube 1 to reduce measurement errors. The final measurement result of the rock-drop GPS is determined by taking the average of multiple measurements. It should be noted that the round-observation method is a conventional technique in this field and will not be elaborated here.

[0034] After the GPS and sonar calibration of the quarry pipe are completed, the leveling vessel is transported to the crushed stone bed laying area so that the quarry pipe 1 can carry out crushed stone bed laying construction. When the leveling vessel arrives at the crushed stone bed laying construction area, the leveling vessel needs to be positioned. The bow and stern of the leveling vessel are respectively equipped with leveling vessel GPS for positioning the leveling vessel.

[0035] During the laying of the crushed stone subgrade, the GPS jacking system needs to measure the laying height, thus requiring secondary verification. In this verification step, a top prism is installed on the top of the jacking pipe 1, and the total station calculates the laying height of the crushed stone subgrade using the top prism. The laying height measured by the total station is compared with that measured by the GPS jacking system. When the difference is within the allowable range, the GPS jacking system's measurement accuracy meets the construction requirements; when the difference exceeds the allowable range, the GPS jacking system does not meet the construction requirements. It should be noted that although the total station's measurement accuracy is higher than that of the GPS jacking system, the total station is more susceptible to light source influences, and its measurement process is more complex. Therefore, during construction, the GPS jacking system is preferred. GPS measurement is more convenient; in actual construction, a total station can also be used to measure the laying height of the crushed stone base bed along the entire length. If a total station is used to measure the laying height of the crushed stone base bed along the entire length, there is no need to verify the measurement results of the total station. It should also be noted that since the GPS measurement results of the riprap pipe directly affect the construction quality, in actual construction, the secondary verification of the riprap pipe GPS is carried out before the riprap pipe 1 is laid. Since the crushed stone base bed has not been laid at this time, the elevation of riprap pipe 1 measured by the total station and the elevation of riprap pipe 1 measured by the riprap pipe GPS are compared to perform the secondary verification of the riprap pipe GPS. In addition, it should be noted that the range of the difference between the elevation of riprap pipe 1 measured by the total station and the elevation of riprap pipe 1 measured by the riprap pipe GPS is selected according to the actual construction conditions and seawater flow velocity, etc.

[0036] It should be noted that during the first calibration of the rock-drop pipe GPS, the GPS measures the bottom of rock-drop pipe 1, which is located in the air. This means that the GPS does not perform underwater measurements. The second calibration of the rock-drop pipe GPS measures the elevation of rock-drop pipe 1, which is placed in the water. This means that the second calibration of the GPS performs underwater measurements. By performing two calibrations, the measurement accuracy of the rock-drop pipe GPS in actual construction can be increased.

[0037] It should also be noted that, because the angle between the top prism of the rock-throwing tube 1 and the total station is too large when the leveling boat is docked at the shore, making measurement inconvenient, a bottom prism is installed at the bottom of the rock-throwing tube 1 during the first GPS calibration to facilitate total station measurement. When the rock-throwing tube 1 throws rocks, the bottom prism installed at the bottom of the rock-throwing tube 1 will be damaged. Therefore, after the first GPS calibration of the rock-throwing tube 1 is completed, the bottom prism installed at the bottom of the rock-throwing tube 1 needs to be removed. In addition, it should be noted that when installing the sonar 2 and the bottom prism, the top prism used in the second GPS calibration step of the rock-throwing tube 1 is also pre-installed on the top of the rock-throwing tube 1.

[0038] Based on the above verification method for the measuring equipment used in laying fully floating gravel bed, the construction of gravel bed generally includes the following steps:

[0039] Three control points were selected based on data provided by the local surveying bureau in order to establish a control network along the shore.

[0040] Install a rock-dropping pipe GPS and a top prism at the top of the rock-dropping pipe 1, and a bottom prism at the bottom of the rock-dropping pipe 1. Install the rock-dropping pipe 1 with the rock-dropping pipe GPS and prism installed on it onto a leveling boat moored on the shore, and raise and lower the pile legs installed around the leveling boat to level the boat.

[0041] The total station measures the horizontal position and elevation of the bottom of the rock-pile tube 1 using a bottom prism. Simultaneously, the rock-pile tube GPS also measures the horizontal position and elevation of the bottom of the rock-pile tube 1. The total station's measurement results are compared with the rock-pile tube GPS's measurement results to perform a check on the rock-pile tube GPS and determine if its measurement accuracy meets the construction requirements. If the difference in horizontal position is within 3cm and the difference in elevation is within 4cm, the measurement accuracy of the rock-pile tube GPS meets the construction requirements, and the bottom prism installed at the bottom of the rock-pile tube 1 is removed. If the difference in horizontal position exceeds 3cm and / or the difference in elevation exceeds 4cm, the measurement accuracy of the rock-pile tube GPS does not meet the construction requirements, and the rock-pile tube GPS needs to be replaced. The replaced rock-pile tube GPS is then checked again until the measurement accuracy meets the construction requirements during the first check.

[0042] The distance from sonar 2 to sonar reflector 3 is measured and the measurement result is compared with the actual extension and retraction of the hydraulic cylinder to determine whether sonar 2 meets the construction requirements. If the difference between the extension and retraction of the hydraulic cylinder and the detection distance of sonar 2 is within the allowable range, the measurement accuracy of sonar 2 meets the construction requirements. If the difference between the extension and retraction of the hydraulic cylinder and the detection distance of sonar 2 exceeds the allowable range, the measurement accuracy of sonar 2 does not meet the construction requirements, and a new sonar 2 needs to be replaced. The replaced sonar 2 is then calibrated.

[0043] When both the GPS and sonar 2 of the rock-throwing pipe meet the construction requirements, the leveling vessel enters the construction site and uses the GPS of the leveling vessel installed at the bow and stern to locate the leveling vessel and the rock-throwing pipe 1 installed on the leveling vessel in the area to be constructed.

[0044] The total station measures the elevation of the rock-filled pipe 1 through the top prism at the top of the pipe. Simultaneously, the rock-filled pipe GPS also measures its elevation. The total station's measurement results are compared with the rock-filled pipe GPS results for secondary verification, determining whether the GPS's measurement accuracy in seawater meets construction requirements. If the difference between the total station's and the GPS's results is within the allowable range, the GPS's measurement accuracy in seawater meets construction requirements, and the rock-filled pipe GPS can be used to measure the elevation of the crushed stone foundation during its laying process. If the difference exceeds the allowable range, the GPS's measurement accuracy in seawater does not meet construction requirements, and only the total station can be used to measure the elevation of the crushed stone foundation.

[0045] Stone-throwing pipe 1 is used to throw stones to lay a crushed stone base bed. During the laying of the crushed stone base bed, the laying elevation of the crushed stone base bed is measured by GPS or total station through the stone-throwing pipe, and the extension and retraction of the hydraulic cylinder is adjusted according to the measurement results, so that the laying of the crushed stone base bed meets the construction requirements.

[0046] The above-mentioned verification method for measuring equipment used in the laying of fully floating crushed stone subgrade can verify the measurement accuracy of the measuring equipment, so as to make the measurement results more accurate, avoid construction errors caused by the accuracy of the measuring equipment, and thus improve the quality of crushed stone subgrade laying; and the verification method is simple and easy to operate.

[0047] Finally, it should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0048] The above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them; although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of the present invention or equivalent substitutions can be made to some technical features without departing from the spirit of the technical solutions of the present invention, and all such modifications and substitutions should be covered within the scope of the technical solutions claimed in the present invention.

Claims

1. A calibration method for a measuring device used for laying a fully floating gravel bed, wherein the gravel bed is laid using a fully floating leveling vessel and a rock-throwing pipe, and the measuring device includes a rock-throwing pipe GPS and a sonar. The rock-throwing pipe GPS is used to measure the laying position and elevation of the gravel bed, and the GPS is installed at the top of the rock-throwing pipe. A hydraulic cylinder for adjusting the length of the rock-throwing pipe is installed at the bottom of the rock-throwing pipe, and the sonar is used to measure the extension of the hydraulic cylinder. The sonar is installed on both sides of the rock-throwing pipe, and the hydraulic cylinder extends and retracts vertically, with a sonar reflector connected to the extension shaft of the hydraulic cylinder. The method is characterized in that... The verification method includes the following steps: Establish a control network: Select at least three control points on the shore to establish a control network, and install a total station at any one location in the control network; GPS initial calibration of the rock-laying pipe: Before rock-laying, the total station measures the rock-laying pipe using a bottom prism installed at the bottom of the pipe; the bottom of the rock-laying pipe is measured using both the total station and the GPS of the rock-laying pipe, and the results are compared; when the difference between the two measurement results is within the allowable range, the measurement accuracy of the GPS of the rock-laying pipe meets the construction requirements; when the difference between the two measurement results exceeds the allowable range, the GPS of the rock-laying pipe does not meet the construction requirements. Sonar verification: Before the rock-throwing pipe throws rocks, the distance from the sonar to the sonar reflector is measured and the measurement result is compared with the actual extension and retraction of the hydraulic cylinder; when the difference between the extension and retraction of the hydraulic cylinder and the detection distance of the sonar is within the allowable range, the sonar meets the construction requirements; when the difference between the extension and retraction of the hydraulic cylinder and the detection distance of the sonar exceeds the allowable range, the sonar does not meet the construction requirements. Secondary verification of GPS for riprap pipe: During the laying of the crushed stone subgrade, the total station calculates the laying height of the crushed stone subgrade using a top prism installed on the top of the riprap pipe; the laying height of the crushed stone subgrade measured by the total station is compared with the laying height of the crushed stone subgrade measured by the GPS of the riprap pipe; when the difference between the two measurement results is within the allowable range, the measurement accuracy of the GPS of the riprap pipe meets the construction requirements; when the difference between the two measurement results exceeds the allowable range, the GPS of the riprap pipe does not meet the construction requirements; In the GPS initial verification step of the rock-throwing pipe, the rock-throwing pipe needs to be installed on the leveling boat first, and the GPS initial verification of the rock-throwing pipe is performed after the leveling boat is leveled; the leveling boat is equipped with pile legs on all four sides, and the leveling boat is leveled by raising and lowering the pile legs. In the GPS verification step of the rock-drop pipe, the total station and the GPS of the rock-drop pipe measure the plane position coordinates and elevation of the bottom of the rock-drop pipe; if the difference in the plane position is within 3cm and the difference in the elevation is within 4cm, it meets the construction requirements.

2. The verification method for the measuring equipment used for laying fully floating gravel bed according to claim 1, characterized in that, The control points were selected from data provided by the local surveying and mapping bureau.

3. The verification method for the measuring equipment used for laying fully floating gravel bed according to claim 1, characterized in that, In the GPS calibration step of the quarry pipe, the total station performs four rounds of observations on the bottom of the quarry pipe to reduce measurement errors.

4. The verification method for the measuring equipment used for laying fully floating gravel bed according to claim 1, characterized in that, Before the GPS of the stone-throwing tube is calibrated, the GPS of the stone-throwing tube and the top prism are installed at the top of the stone-throwing tube, and the bottom prism is installed at the bottom of the stone-throwing tube.

5. The verification method for the measuring equipment used for laying fully floating gravel bed according to claim 4, characterized in that, After the GPS calibration step of the stone-throwing tube is completed, the bottom prism at the bottom of the stone-throwing tube is removed.

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