Drain board construction method

Abstract

The invention discloses a drain board construction method which comprises the following steps: arranging drain board positioning grids on the surface of a soft soil foundation to be treated, and controlling plane coordinates by adopting RTK-GPS (Real Time Kinematic-Global Positioning System) positioning equipment; a crawler-type plate inserting machine is adopted to carry out water drainage plate driving, a double-shaft tilt angle sensor is installed on a mast of the plate inserting machine, and the perpendicularity of the mast is adjusted in real time through a hydraulic servo mechanism; when the depth of the bottom ends of the drainage plates entering the bearing stratum reaches 500-800 mm, driving is stopped, the exposed length of the top ends of the drainage plates is reserved to be 400-500 mm, and the distance between the centers of the adjacent drainage plates is controlled to be 0.8-1.2 m; a sealing film is laid in the drainage plate area, an exposed end is reserved for the drainage plate, a filter pipe is connected along the exposed end of the drainage plate, and the filter pipe is connected with the drainage plate through a socket type rubber connector; installing a vacuum pump unit and connecting a vacuum degree sensor; and covering a medium-coarse sand protection layer on the surface of the sealing film. Accurate control over drainage plate construction can be achieved, the construction quality and efficiency are improved, and the labor cost is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field related to the construction of soft soil foundations. More specifically, the present invention relates to a construction method for drainage boards. Background Art

[0002] In the construction of projects such as roads, ports, and airports, the reinforcement treatment of soft soil foundations is a key link to ensure the stability of the project. However, traditional construction methods for drainage boards usually have problems such as insufficient positioning accuracy. When using manual lofting or conventional GPS positioning, the plane positioning deviation is likely to exceed 50 mm, resulting in uneven distribution of drainage boards and affecting the consolidation effect. Moreover, it is difficult to achieve dynamic coordinate correction under complex geological conditions; the control of verticality is rough. The verticality of the mast of the board inserter depends on manual experience adjustment, and the verticality deviation generally exceeds 3%, resulting in a shortened effective drainage length of the drainage board and even problems such as broken boards and blockages; poor parameter adaptability, without differential design for different compressible soil layers, uniformly using fixed spacing and driving depth, which is likely to cause insufficient drainage efficiency in high compressibility areas and waste of resources in low compressibility areas; lagging construction data management, relying on manual recording of construction parameters, with poor data integrity and timeliness, and unable to achieve real-time monitoring and dynamic optimization of the construction process. Therefore, it is necessary to design a technical solution that can overcome the above defects. Summary of the Invention

[0003] An object of the present invention is to provide a construction method for drainage boards, which can accurately control the construction of drainage boards, improve construction quality and efficiency, and reduce labor costs.

[0004] To achieve these objects and other advantages of the present invention, according to one aspect of the present invention, there is provided a construction method for drainage boards, including: laying a drainage board positioning grid on the surface of the soft soil foundation to be treated, and controlling the plane coordinates by using RTK-GPS positioning equipment; implementing the driving of drainage boards by using a crawler-type board inserter, installing a dual-axis inclination sensor on the mast of the board inserter, and adjusting the verticality of the mast in real time through a hydraulic servo mechanism to make the verticality deviation of the drainage board less than 1.5%; stopping driving when the depth of the bottom end of the drainage board entering the bearing stratum reaches 500 to 800 mm, and leaving an exposed length of 400 mm to 500 mm at the top end, and controlling the center distance between adjacent drainage boards to be 0.8 m to 1.2 m; laying a sealing film in the drainage board area, and reserving an exposed end for the drainage board, connecting a filter pipe along the exposed end of the drainage board, and connecting the filter pipe and the drainage board with a socket rubber joint; installing a vacuum pump unit and connecting a vacuum degree sensor, and automatically starting a standby vacuum pump unit when the vacuum degree under the film is lower than 80 kPa; covering a medium-coarse sand protection layer on the surface of the sealing film, with a sand layer thickness of 300 mm to 400 mm and a sand particle size of 0.5 mm to 5 mm.

[0005] Furthermore, divide the bearing capacity difference regions according to the static cone penetration test data of the soft soil foundation. Adopt a densified spacing of 0.8 m in the high compressibility region, a spacing of 1.0 m in the medium compressibility region, and a widened spacing of 1.2 m in the low compressibility region; import the grid parameters into the RTK-GPS navigation system of the vertical drain machine. Receive satellite signals in real time through the dual-frequency receiver in the traveling direction of the vertical drain machine, and combine with the laser elevation scanning data of the foundation surface to generate a three-dimensional construction navigation interface on the vehicle-mounted terminal, dynamically correcting the plane coordinate deviation to ≤15 mm; for each vertical drain installed by the vertical drain machine, automatically generate an encrypted data packet containing the installation point coordinates, installation time, verticality correction amount, and soil layer resistance curve, and upload it to the cloud construction management platform.

[0006] Furthermore, conduct static cone penetration tests in the construction area according to a 10 m × 10 m grid to obtain the distribution cloud map of the cone tip resistance value qc; divide the foundation into three types of regions according to the qc value: in the high compressibility region where qc ≤ 0.5 MPa, the vertical drains are arranged in an equilateral triangle with a center spacing of 0.8 m ± 0.05 m; in the medium compressibility region where 0.5 MPa < qc ≤ 1.0 MPa, the vertical drains are arranged in a square grid with a center spacing of 1.0 m ± 0.05 m; in the low compressibility region where qc > 1.0 MPa, the vertical drains are arranged in a plum blossom grid with a center spacing of 1.2 m ± 0.05 m; the vertical drain machine is equipped with a dual-frequency RTK-GPS module and a terrestrial laser scanner. Obtain the surface elevation data of the construction point in real time through the laser scanner, calculate the track settlement compensation amount ΔS in combination with the inclination sensor data of the vertical drain machine, solve the plane coordinates (X, Y) based on the dual-frequency RTK signal, and perform three-dimensional coordinate correction by superimposing ΔS to generate a dynamic navigation path; when the real-time positioning deviation exceeds the threshold, trigger the hydraulic servo system of the vertical drain machine to adjust the body position until the deviation value ≤ the set threshold.

[0007] Furthermore, install biaxial inclination sensors at the top and bottom of the mast of the vertical drain machine respectively, and synchronously collect the inclination angles θ1 and θ2 of the mast in the X / Y axes at a frequency of 200 Hz; calculate the mast bending deformation difference Δθ = │θ1 - θ2│. When Δθ ≥ 0.1°, trigger a shutdown alarm and generate a mast mechanical fault diagnosis report; according to the obtained cone tip resistance value qc, set the parameters of the hydraulic servo mechanism according to the following rules: for the soft soil layer where qc ≤ 0.5 MPa: set the response speed of the hydraulic cylinder to 0.8 m / s, and the single correction stroke ≤ 5 mm; for the hard soil layer where qc > 0.5 MPa: set the response speed of the hydraulic cylinder to 1.2 m / s, and the single correction stroke ≤ 3 mm; calculate the target correction direction and stroke based on the real-time inclination angles θ1 and θ2, control the action of the hydraulic servo mechanism, and converge the mast verticality deviation to ≤ 1.5% within 0.5 seconds.

[0008] Furthermore, synchronously measure data through the dual-axis inclinometers at the top and bottom of the mast to construct a mast spatial offset model: convert the X / Y-axis inclinations of the top sensor into horizontal offsets based on the effective height of the mast, and calculate the local offset components according to the installation positions of the X / Y-axis inclinations of the bottom sensor; by comparing the vector synthesis results of the top and bottom offsets, when the comprehensive offset reaches 1.5% of the effective height of the mast, perform three-level deviation correction: Coarse adjustment stage: Dynamically adjust the hydraulic cylinder propulsion speed based on the tilt angle phase difference and the soil layer qc value classification; Fine adjustment stage: Predict the movement trajectory by combining the mast vibration historical data, and achieve millimeter-level stroke correction through feedforward compensation; Locking stage: Call the laser scanning device of the sheet inserter to verify the verticality, and trigger the hydraulic system self-locking when the continuous three measurement values are all lower than 1.5%.

[0009] Furthermore, for the highly compressible area, the driving depth is set to 800mm ± 50mm, and the exposed length at the top is reserved as 500mm ± 20mm; for the moderately compressible area, the driving depth is set to 650mm ± 50mm, and the exposed length at the top is reserved as 450mm ± 20mm; for the low compressible area, the driving depth is set to 500mm ± 50mm, and the exposed length at the top is reserved as 400mm ± 20mm; when the penetration resistance of the sheet inserter reaches 120% of the qc threshold of the current area, stop driving.

[0010] Furthermore, lay the PE sealing film in sheets based on the grid generated by RTK-GPS positioning, and form continuous welds at the lap joints of adjacent film sheets through hot air welding equipment; the extended sealing ring of the socket rubber joint is bonded to the outer wall of the drainage board through hot melt adhesive to form a sealing structure, forming a sealing structure that wraps the exposed end of the drainage board; the socket rubber joint has an interference fit with the outer wall of the drainage board; after sealing, apply negative pressure through the vacuum pump unit, and when the vacuum degree data is stable above 80 kPa, determine that the sealing is qualified.

[0011] Furthermore, arrange the main vacuum pump unit at the boundary of the sealing film, and its total air extraction volume matches the total length of the filter pipes; install a standby pump unit on the sheet inserter carrier, and the air extraction capacity is 120% of the main pump unit; install a vacuum degree sensor at the filter pipe connection point, with a measuring range of 0 - 100 kPa, and upload the data to the cloud construction management platform in real time; when the regional vacuum degree is continuously lower than 80 kPa for a predetermined time, automatically activate the standby pump unit.

[0012] Furthermore, use a loader to evenly spread medium-coarse sand, control the sand layer thickness between 300mm and 400mm, and the sand particle size is 0.5mm to 5mm; use a vibratory roller to reciprocally compact the sand layer, and the number of compaction passes is 3 - 5 times. After compaction, use the core cutter method to detect the compactness of the sand layer, and control the dry density ≥ 1.7 g / cm³; lay geotextile on the surface of the sand layer to prevent the subsequent construction machinery from directly crushing and damaging the sand layer structure.

[0013] The present invention has at least the following beneficial effects: Through the RTK-GPS positioning device and dual-frequency receiver of the present invention, combined with the ground surface laser elevation scanning data, the planar coordinate deviation can be dynamically corrected to ≤15 mm, making the distribution of drainage plates more uniform and effectively improving the consolidation effect of the foundation; a dual-axis inclination sensor is installed on the mast, and together with the hydraulic servo mechanism, the mast verticality deviation can be quickly converged to ≤1.5%, reducing the phenomena of broken plates and blockages and ensuring the effective drainage length of the drainage plates; the bearing capacity difference areas are divided according to the static cone penetration test data of the soft soil foundation, and different spacings and driving depths are adopted in different compressibility areas, which not only improves the drainage efficiency in the high compressibility area but also avoids resource waste in the low compressibility area; the present invention can achieve precise control of the drainage plate construction, improve the construction quality and efficiency, and reduce the labor cost.

[0014] Other advantages, objectives, and features of the present invention will be partially reflected by the following description and partially understood by those skilled in the art through the research and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a flowchart of an embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0016] The following further describes the present invention in detail with reference to the drawings, so that those skilled in the art can implement it according to the description in the specification.

[0017] It should be understood that terms such as "having", "including", and "comprising" used in the embodiments of the present application do not exclude the existence or addition of one or more other elements or their combinations. All directional indications (such as up, down, left, right, front, back...) in the embodiments of the present application are only used to explain the relative positional relationship and movement conditions between components in a specific posture. If the specific posture changes, the directional indications will also change accordingly. When an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or there may be an intermediate element at the same time. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or indirectly connected to the other element through an intermediate element. The descriptions in the embodiments of the present application involving "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one such feature.

[0018] It should be noted that the technical solutions between the various embodiments of the present application can be combined with each other, but it must be based on the realization by those of ordinary skill in the art. When the combination of technical solutions is contradictory or cannot be realized, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present application.

[0019] As Figure 1 shown, the embodiments of the present application provide a construction method for drainage boards, including: first, using an RTK-GPS positioning device to control the plane coordinates on the surface of the soft soil foundation to be treated, and laying out a drainage board positioning grid; then using a crawler-type inserter to drive the drainage boards, and adjusting the mast verticality in real time through a biaxial inclination sensor and a hydraulic servo mechanism; when the bottom end of the drainage board enters the bearing stratum to a suitable depth, stop driving, retain a suitable exposed length at the top, and control the center distance between adjacent drainage boards; then lay a sealing film in the drainage board area, reserve the exposed ends of the drainage boards, and connect the filter pipes; then install a vacuum pump unit and connect a vacuum degree sensor, and automatically start the standby vacuum pump unit when the vacuum degree under the film is lower than the set value; finally, cover a protective layer of medium-coarse sand with a suitable thickness and particle size on the surface of the sealing film; When laying out the drainage board positioning grid on the surface of the soft soil foundation to be treated, for numerical selection, the plane coordinates can be controlled within a certain accuracy range, such as controlling the plane coordinate error within ±50 mm. In terms of equipment selection, common RTK-GPS positioning devices on the market can be selected. In terms of material selection, the drainage board positioning grid can use grid lines made of nylon material. The RTK-GPS positioning device should be installed in a place where the surface position of the soft soil foundation to be treated can be accurately measured, generally installed near the soft soil foundation and in an open area.

[0020] When using a crawler-type inserter to drive the drainage boards, in terms of numerical selection, the verticality deviation of the drainage boards can be set to a value less than 1.5% such as 1%; the accuracy of the biaxial inclination sensor can be selected as a higher accuracy value such as 0.1°. In terms of materials, high-strength composite drainage boards can be used for the drainage boards. The biaxial inclination sensor is installed on the mast of the inserter, and the hydraulic servo mechanism is installed at the hydraulic system part related to the adjustment of the mast verticality of the inserter.

[0021] When the depth of the bottom end of the drainage board entering the bearing stratum reaches 500 to 800 mm, stop driving. In terms of numerical selection, the depth of the bottom end of the drainage board entering the bearing stratum can be selected as 600 mm, 700 mm, etc.; the exposed length at the top can be selected as 420 mm, 480 mm, etc.; the center distance between adjacent drainage boards can be selected as 1.0 m, etc. In terms of equipment, there is no new equipment selection. In terms of materials, the high-strength composite drainage boards mentioned before are still used for the drainage boards.

[0022] Lay the sealing film in the drainage board area and connect the filter pipes. There are no special new values in terms of numerical selection. In terms of equipment selection, PVC filter pipes can be chosen for the filter pipes, and socket rubber joints can be chosen as socket rubber joints made of ethylene propylene diene monomer (EPDM) rubber. In terms of materials, polyethylene sealing film can be chosen for the sealing film. The socket rubber joint is installed at the connection between the filter pipe and the drainage board, and the filter pipe is connected along the exposed end of the drainage board.

[0023] Install the vacuum pump unit and connect the vacuum sensor. In terms of numerical selection, the set value of the vacuum under the film is 80 kPa. When it is lower than this value, the standby vacuum pump unit will be automatically started, and the vacuum difference value for starting the standby vacuum pump unit can be set to 5 kPa, etc. In terms of equipment selection, Busch vacuum pump units can be chosen. The vacuum pump unit is installed at a position near the sealing film for easy connection, and the vacuum sensor is installed at a position where the vacuum under the film can be accurately measured, generally at a suitable position inside the sealing film.

[0024] Cover the surface of the sealing film with a medium-coarse sand protection layer. In terms of numerical selection, the thickness of the sand layer can be chosen as 320 mm, 380 mm, etc.; the particle size of the sand grains can be chosen as 1 mm, 3 mm, etc. There is no new equipment selection in terms of equipment. In terms of materials, natural river sand can be chosen for the medium-coarse sand. The medium-coarse sand is laid on the surface of the sealing film to form a protection layer.

[0025] The plane coordinates are determined through the relevant settings and measurements of RTK-GPS positioning equipment; the verticality deviation of the drainage board is monitored in real time by a biaxial inclination sensor and controlled by a hydraulic servo mechanism; the depth of the bottom end of the drainage board entering the bearing stratum, the exposed length of the top end, and the center spacing of adjacent drainage boards are achieved through the measurements and controls during the operation of the inserting machine; the vacuum under the film is measured by a vacuum sensor, and the vacuum pump unit is automatically started and stopped according to the measured value for control; the thickness of the sand layer and the particle size of the sand grains are ensured by selecting suitable medium-coarse sand materials and the control during the laying process.

[0026] The drainage effect of the drainage board can be tested by measuring the drop of the water level in the soft soil foundation within a certain period of time; the sealing performance of the sealing membrane can be tested by monitoring the stability of the vacuum under the membrane; the working performance of the vacuum pump unit can be tested, including the accuracy and stability of starting and stopping. Structural design: The drainage board is designed to be a suitable structure to ensure drainage performance and strength; the sealing membrane is designed to be a structure that can effectively seal; the filter tube and the socket rubber joint are designed to be easy to connect and seal. A representative soft soil foundation to be treated is selected as the experimental object. Experimental method: According to the above overall use method, the drainage board is constructed on the experimental object. During and after the construction process, various parameters are measured and recorded, such as the verticality of the drainage board, the vacuum under the membrane, and the drainage effect. The data of multiple experiments are statistically analyzed, and the statistical quantities such as the mean value and standard deviation of each parameter are calculated, the correlation between the parameters is analyzed, and the stability and reliability of the construction method are evaluated.

[0027] This embodiment uses RTK-GPS positioning equipment to control plane coordinates, which can improve the accuracy of drain board positioning, make the drain boards more evenly distributed, and effectively improve the foundation consolidation effect; use dual-axis inclination sensors and hydraulic servo mechanisms to adjust the verticality of the mast in real time, which can ensure that the verticality deviation of the drain boards is small, reduce the occurrence of broken boards and clogging, and ensure the effective drainage length of the drain boards, which is beneficial to the drainage effect; reasonably control the depth of the bottom of the drain board entering the bearing layer, the exposed length of the top and the center distance between adjacent drain boards, which can optimize the performance of the drainage system; covering with a suitable medium-coarse sand protective layer can protect the sealing membrane and improve the stability and durability of the entire drainage system; in short, this embodiment can achieve precise control of the construction of the drain boards, improve construction quality and efficiency, and reduce labor costs.

[0028] In another embodiment, a static penetration test is performed on a soft soil foundation using a static penetration test device, and the bearing capacity difference area is divided according to the test data, 0.8m or other suitable encrypted spacing is used in the high compressibility area, 1.0m or similar spacing is used in the medium compressibility area, and 1.2m is used in the low compressibility area. The grid parameters are then imported into the RTK-GPS navigation system of Southern Surveying and Mapping installed on the plug-in machine, and the satellite signal is received in real time by a dual-frequency receiver of Qianxun Position installed in the direction of travel of the plug-in machine. At the same time, a laser scanner of Faru is used to perform laser elevation scanning on the foundation surface to obtain data, and a three-dimensional construction navigation interface is generated on the Advantech vehicle-mounted terminal installed in the cab of the plug-in machine, and the plane coordinate deviation is dynamically corrected to ≤15mm or less. Every time the plug-in machine completes the installation of a drainage board, an encrypted data packet containing the installation point coordinates, installation time, verticality correction amount and soil resistance curve is automatically generated using the storage module installed in the plug-in machine, and uploaded to the cloud construction management platform.

[0029] For the spacing of different compressibility regions, in the high compressibility region, in addition to 0.8 m, similar values such as 0.75 m can also be selected; in the medium compressibility region, in addition to 1.0 m, 0.95 m etc. can also be selected; in the low compressibility region, in addition to 1.2 m, 1.15 m etc. can also be selected. In terms of equipment selection, the static cone penetration test equipment of Haichuang Hi-Tech can be selected to conduct the static cone penetration test on soft soil foundation. There is no special material selection in terms of materials. The static cone penetration test equipment of Haichuang Hi-Tech should be installed at a suitable test position on the soft soil foundation for test operation.

[0030] The plane coordinate deviation can be set to a smaller value such as ≤10 mm etc. to improve the accuracy. The RTK-GPS navigation system is installed at a suitable control position of the jet grouting machine, the dual-frequency receiver is installed at a position convenient for receiving satellite signals in the advancing direction of the jet grouting machine, the ground surface laser elevation scanning equipment is placed at a suitable position when scanning the ground surface, and the vehicle-mounted terminal is installed at a position convenient for the operator to view in the cab of the jet grouting machine.

[0031] Every time the jet grouting machine completes the installation of a drainage board, it automatically generates an encrypted data packet and uploads it. A storage module with data generation and upload functions can be selected and installed on the jet grouting machine. The cloud construction management platform can select the cloud platform service of Alibaba Cloud. There is no special material selection in terms of materials. The storage module is installed at a suitable position inside the jet grouting machine to facilitate the recording and storage of relevant data.

[0032] The spacing of different compressibility regions is set according to the static cone penetration test data of the soft soil foundation and engineering experience; the plane coordinate deviation is dynamically corrected and controlled through the coordinated work of the RTK-GPS navigation system, dual-frequency receiver, ground surface laser elevation scanning equipment and vehicle-mounted terminal; the generation and upload of the encrypted data packet are realized by the settings of the storage module installed in the jet grouting machine and the cloud construction management platform; In this embodiment, the bearing capacity difference regions are divided according to the static cone penetration test data of the soft soil foundation and different spacings are adopted, which can arrange the drainage boards more reasonably. In the high compressibility region, the encrypted spacing is adopted to improve the drainage efficiency, and in the low compressibility region, the widened spacing is adopted to avoid waste of resources; the grid parameters are imported into the RTK-GPS navigation system of the jet grouting machine, combined with the dual-frequency receiver, ground surface laser elevation scanning data and vehicle-mounted terminal, and the plane coordinate deviation is dynamically corrected to ≤15 mm, which improves the accuracy of the installation position of the drainage board, makes the distribution of the drainage board more uniform, and effectively improves the foundation consolidation effect; every time the jet grouting machine completes the installation of a drainage board, it automatically generates and uploads an encrypted data packet containing a variety of key information, which is convenient for construction management and quality traceability, can grasp the construction situation in real time, further improves the construction quality and efficiency, and also helps to optimize the construction process and reduce the labor cost.

[0033] In another embodiment, first, in the construction area, according to a grid size of 10m×10m or other selected grid sizes, a static cone penetration test is carried out using a static cone penetration testing device to obtain the distribution contour map of the cone tip resistance value qc; the foundation is divided into a high compressibility area (qc≤0.5MPa), a medium compressibility area (0.5MPa<qc≤1.0MPa), and a low compressibility area (qc>1.0MPa); in the high compressibility area, the high-strength composite drainage plates produced by Honglu Steel Structure are arranged in an equilateral triangle with a center spacing of 0.8m±0.05m or other appropriate values, in the medium compressibility area, they are arranged in a square grid with a center spacing of 1.0m±0.05m, and in the low compressibility area, they are arranged in a plum blossom grid with a center spacing of 1.2m±0.05m or corresponding values; for the double-frequency RTK-GPS module and the terrestrial laser scanner of the plate inserter, the elevation data of the construction point surface is obtained in real time through the terrestrial laser scanner, and the track settlement compensation amount ΔS is calculated by combining the data of the tilt sensor installed on the plate inserter. Based on the double-frequency RTK signal, the plane coordinates (X, Y) are solved, and the three-dimensional coordinates are corrected by superimposing ΔS to generate a dynamic navigation path; when the real-time positioning deviation exceeds the set threshold (such as 20mm, etc.), the hydraulic servo system installed on the plate inserter is triggered to adjust the position of the fuselage until the deviation value ≤ the set threshold.

[0034] In addition to 10m×10m, the grid size can also be selected as 8m×8m or 12m×12m, etc.; for obtaining the distribution contour map of the cone tip resistance value qc, during data processing, different selection options can be made for the accuracy parameters of the contour map. For example, the accuracy can be set at different intervals such as 0.05MPa to present the contour map. In terms of equipment selection, a static cone penetration testing device of Yutong Heavy Industry can be selected for the test, and this device can accurately obtain the cone tip resistance value. There is no special material selection in terms of materials. The static cone penetration testing device of Yutong Heavy Industry should be installed at the corresponding grid points in the construction area for the static cone penetration test operation.

[0035] The calculation accuracy of the track settlement compensation amount ΔS can be set to different values, such as 0.01m, etc.; the threshold of the real-time positioning deviation can be set to different values, such as 20mm, etc., and the set threshold can be adjusted according to the actual requirements of the project. The double-frequency RTK-GPS module is installed at a position on the plate inserter that is convenient for receiving signals, the terrestrial laser scanner is installed at a position on the plate inserter that can obtain the elevation data of the construction point surface in real time, the tilt sensor of the plate inserter is installed at a position that can accurately measure the tilt angle of the plate inserter, and the hydraulic servo system of the plate inserter is installed at the position of the plate inserter fuselage to adjust the fuselage.

[0036] In this embodiment, a static cone penetration test is carried out in the construction area according to a suitable grid, and a distribution contour map of the cone tip resistance value qc is obtained, which can more accurately divide the foundation compressibility area; the foundation is divided into three types of areas according to different qc values, and different drainage board arrangements and spacings are adopted to make the drainage board arrangement more reasonable, improve the drainage efficiency in the high compressibility area, and avoid resource waste in the low compressibility area; the inserter is equipped with devices such as a dual-frequency RTK-GPS module and a terrestrial laser scanner, calculates the crawler settlement compensation amount in combination with the data of the inclinometer sensor, and corrects the three-dimensional coordinates to generate a dynamic navigation path. When the real-time positioning deviation exceeds the threshold, the fuselage position is adjusted, which improves the accuracy of the drainage board driving position and the accuracy of the three-dimensional space, makes the drainage board distribution more uniform, effectively improves the foundation consolidation effect, and at the same time improves the degree of construction automation, further improves the construction quality and efficiency, and reduces the labor cost.

[0037] In another embodiment, biaxial inclinometer sensors are installed at the top and bottom of the inserter mast, and the inclination angles θ1 and θ2 of the mast X / Y axes are synchronously collected at a frequency of 200Hz or other selected frequencies; calculate the mast bending deformation difference Δθ = │θ1 - θ2│. When Δθ reaches or exceeds the set threshold (such as 0.1° or other values), trigger the shutdown alarm of the inserter, and use the control system of the inserter itself to generate a mast mechanical fault diagnosis report; according to the obtained cone tip resistance value qc, according to the set rules, when the qc of the soft soil layer ≤ 0.5MPa, set the response speed of the hydraulic cylinder in the hydraulic servo mechanism to 0.8m / s or other appropriate values, and set the single correction stroke to ≤ 5mm or corresponding values. When the qc of the hard soil layer > 0.5MPa, set the response speed of the hydraulic cylinder to 1.2m / s or other values, and set the single correction stroke to ≤ 3mm; calculate the target correction direction and stroke based on the real-time collected inclination angles θ1 and θ2, and control the action of the hydraulic servo mechanism installed on the inserter to converge the mast verticality deviation to ≤ 1.5% or other set thresholds within 0.5 seconds or other set times.

[0038] Calculate the mast bending deformation difference and trigger the shutdown alarm. In terms of numerical selection, in addition to 0.1°, the threshold of the bending deformation difference can also be 0.08° etc.; there can be different settings for the details of generating the mast mechanical fault diagnosis report and the data recording frequency, etc. There is no new special equipment selection in terms of equipment, mainly relying on the installed biaxial inclinometer sensor and the control system of the inserter itself to perform calculation and alarm operations.

[0039] Set the parameters of the hydraulic servo mechanism and control the verticality of the mast according to the tip resistance value. In terms of numerical selection, in addition to 0.5 MPa, the qc threshold for soft soil layer and hard soil layer can also be 0.48 MPa, etc.; the response speed of the hydraulic cylinder in the soft soil layer can be 0.7 m / s, etc. in addition to 0.8 m / s, and in the hard soil layer can be 1.1 m / s, etc. in addition to 1.2 m / s; the single correction stroke in the soft soil layer can be ≤4 mm, etc. in addition to ≤5 mm, and in the hard soil layer can be ≤2.5 mm, etc. in addition to ≤3 mm; the time for converging the verticality deviation of the mast can be 0.6 seconds, etc. in addition to 0.5 seconds, and the verticality deviation threshold can be ≤1.2%, etc. in addition to ≤1.5%.

[0040] In this embodiment, biaxial inclination sensors are installed at the top and bottom of the mast of the wick drain machine, and the inclination angles are synchronously collected at a certain frequency, which can more accurately obtain the inclination state information of the mast. By calculating the difference in mast bending deformation and setting a reasonable threshold, when the difference reaches a certain level, the shutdown alarm is triggered and a fault diagnosis report is generated, so that the mechanical faults of the mast can be detected in time, and construction problems caused by mast faults can be avoided; the parameters of the hydraulic servo mechanism are set according to the tip resistance value, and different hydraulic cylinder response speeds and single correction strokes are adopted for soft soil layer and hard soil layer, so that the control of the hydraulic servo mechanism is more in line with the actual construction situation; based on the real-time inclination, the target correction direction and stroke are calculated, which can quickly and effectively control the action of the hydraulic servo mechanism, converge the verticality deviation of the mast to the specified range in a short time, ensure the verticality during the installation of the wick drain, reduce the occurrence of broken plates and blockages, ensure the effective drainage length of the wick drain, and then improve the construction quality of the wick drain and the foundation treatment effect. At the same time, it improves the level of automatic monitoring and control during the construction process, reduces the construction risk and labor cost.

[0041] In another embodiment, data is synchronously measured first through biaxial inclinometers installed at the top and bottom of the mast of the inserting machine. The X / Y-axis inclinations of the top sensor are converted into horizontal offsets based on the effective height of the mast, and the X / Y-axis inclinations of the bottom sensor are used to calculate local offset components according to their installation positions, thereby constructing a spatial offset model of the mast. Then, the vector synthesis results of the top and bottom offsets are compared. When the comprehensive offset reaches 1.5% of the effective height of the mast or other set ratios, three-level deviation correction is performed. In the rough adjustment stage, based on the classification of the tilt angle phase difference and the qc value of the soil layer, a hydraulic servo mechanism installed at the position connected to the hydraulic cylinder on the inserting machine is used to dynamically adjust the advancing speed of the hydraulic cylinder. In the fine adjustment stage, the control system of the inserting machine is used to predict the movement trajectory in combination with the mast vibration history data, and millimeter-level or more precise stroke correction is achieved through feedforward compensation. In the locking stage, a laser scanning device installed at a suitable position on the inserting machine is used for verticality verification. When the measured values are lower than 1.5% or other set thresholds for three consecutive times or other set numbers of times, the installed hydraulic servo mechanism on the inserting machine is triggered to achieve self-locking of the hydraulic system.

[0042] A spatial offset model of the mast is constructed by synchronously measuring data through biaxial inclinometers. In terms of numerical selection, when converting the X / Y-axis inclinations of the top sensor into horizontal offsets, different calculation accuracies can be selected. For example, the accuracy can be set to 0.001 m, etc. When calculating the local offset components from the X / Y-axis inclinations of the bottom sensor, its accuracy can also be adjusted, such as 0.002 m, etc.

[0043] In the rough adjustment stage of performing three-level deviation correction according to the offset, in terms of numerical selection, in addition to 1.5%, the ratio of the comprehensive offset to the effective height of the mast can also be 1.2%, etc. When the advancing speed of the hydraulic cylinder is dynamically adjusted according to the classification of the tilt angle phase difference and the qc value of the soil layer, the speed range can vary. For example, in soft soil layers, the speed can be adjusted between 0.6 m / s and 1.0 m / s, and in hard soil layers, it can be adjusted between 1.0 m / s and 1.4 m / s, etc.

[0044] In the technical features of the fine adjustment stage and the locking stage, in terms of numerical selection, when predicting the movement trajectory in combination with the mast vibration history data for millimeter-level stroke correction in the fine adjustment stage, in addition to the millimeter level, the stroke correction accuracy can be more precise to 0.5 mm, etc. In the locking stage, in addition to three times, the number of consecutive measurements during verticality verification can also be four times, etc. In addition to 1.5%, the verticality threshold can also be 1.2%, etc.

[0045] In this embodiment, a spatial offset model of the mast is constructed by synchronously measuring data with biaxial inclinometers at the top and bottom of the mast, which can more accurately reflect the spatial offset state of the mast and provide a reliable basis for subsequent deviation correction. When the comprehensive offset reaches a certain proportion, three-level deviation correction is performed. In the rough adjustment stage, the advancing speed of the hydraulic cylinder is dynamically adjusted according to the phase difference of the inclination angle and the qc value of the soil layer, making the deviation correction operation more in line with the actual construction conditions. In the fine adjustment stage, the motion trajectory is predicted by combining the historical vibration data of the mast and millimeter-level stroke correction is achieved through feedforward compensation, improving the accuracy of deviation correction. In the locking stage, the perpendicularity is verified by a laser scanning device and the hydraulic system is triggered to self-lock when the conditions are met, ensuring the stability of the mast perpendicularity. These measures effectively guarantee the perpendicularity of the mast during the installation of drainage plates, further reducing the occurrence of broken plates and blockages, increasing the effective drainage length of the drainage plates, improving the quality and accuracy of drainage plate construction, making the automatic control of the construction process more perfect, reducing the risks brought by mast offset during the construction process, improving the construction efficiency, and saving labor costs.

[0046] In another embodiment, first, high compressibility regions (qc ≤ 0.5 MPa), medium compressibility regions (0.5 MPa < qc ≤ 1.0 MPa), and low compressibility regions (qc > 1.0 MPa) are divided according to the static cone penetration test data of the soft soil foundation. In the high compressibility region, the driving depth of the high-strength composite drainage plates produced by Honglu Steel Structure is set to 800 mm ± 50 mm using equipment such as Yutong YT-180 crawler type sheet pile inserter, and the exposed length at the top is reserved as 500 mm ± 20 mm. In the medium compressibility region, the driving depth is set to 650 mm ± 50 mm, and the exposed length at the top is reserved as 450 mm ± 20 mm. In the low compressibility region, the driving depth is set to 500 mm ± 50 mm, and the exposed length at the top is reserved as 400 mm ± 20 mm. During the driving process, the penetration resistance is measured in real time using a force sensor produced by HBM Company installed on the penetration component of the sheet pile inserter. When the penetration resistance of the sheet pile inserter reaches 120% or other set ratios of the qc threshold of the current region, the driving is stopped.

[0047] Regarding the selection of the driving depth and the exposed length at the top of the drainage plates in different compressibility regions, for the high compressibility region, in addition to 800 mm ± 50 mm, similar values such as 780 mm ± 50 mm can also be selected for the driving depth, and in addition to 500 mm ± 20 mm, values such as 480 mm ± 20 mm can also be selected for the exposed length at the top. For the medium compressibility region, the driving depth can be selected as 630 mm ± 50 mm, etc., and the exposed length at the top can be selected as 430 mm ± 20 mm, etc. For the low compressibility region, the driving depth can be selected as 480 mm ± 50 mm, etc., and the exposed length at the top can be selected as 380 mm ± 20 mm, etc.

[0048] When the penetration resistance of the inserter reaches 120% of the qc threshold of the current area, in terms of numerical selection, in addition to 120%, the threshold ratio of the penetration resistance can also be 125% or the like. In terms of equipment, it mainly relies on the resistance measurement device of the inserter itself to detect the penetration resistance. For example, the inserter can be equipped with a force sensor to measure the penetration resistance, and the force sensor can be selected to be installed on the penetration component of the inserter.

[0049] In this embodiment, different depths of the drainage plate driving and the exposed length at the top are set according to different compressibility regions, fully considering the actual situation of the foundation. In the high compressibility region, appropriately increasing the driving depth and the exposed length at the top can better adapt to the drainage requirements of the high compressibility foundation, improve the drainage efficiency, and enhance the consolidation effect of the foundation; the parameter setting in the medium compressibility region is relatively moderate, which not only ensures the drainage effect but also reasonably utilizes resources; reducing the driving depth and the exposed length at the top in the low compressibility region avoids unnecessary resource waste. Stopping the driving when the penetration resistance of the inserter reaches a certain proportion of the qc threshold of the current area provides a more scientific and reasonable judgment basis for the driving depth, avoiding the situation of driving too deep or too shallow, ensuring that the drainage plate can effectively play its role, further improving the quality and effect of the drainage plate construction, optimizing the process of foundation treatment, realizing the reasonable utilization of resources while ensuring the quality of foundation treatment, and reducing the construction cost.

[0050] In another embodiment, first, based on the grid generated by RTK-GPS positioning, the PE sealing film is selected for laying in sections, and a hot air welding device produced by Changzhou Mingjin Machinery is used to perform hot air welding on the overlapping parts of adjacent film sheets to form a continuous weld; a socket rubber joint made of ethylene propylene diene monomer rubber produced by Hebei Zhongzhentong Rubber Company is connected to the drainage plate. The extended sealing ring of the socket rubber joint is bonded to the outer wall of the drainage plate through hot melt adhesive, and the socket rubber joint and the outer wall of the drainage plate are in interference fit to form a sealing structure that wraps the exposed end of the drainage plate; after sealing, a vacuum pump unit is installed to apply negative pressure to the sealed area, and a vacuum sensor is used to measure the vacuum degree. When the vacuum degree data is stable above 80 kPa and reaches the set time (such as 30 minutes), it is determined that the seal is qualified; In addition to meeting the welding requirements, the overlapping width of adjacent film sheets; the welding temperature and time of the hot air welding device can be adjusted according to the material of the PE sealing film. For example, the welding temperature can be selected between 200°C and 250°C, and the welding time can be selected between 5 seconds and 10 seconds, etc. In terms of equipment selection, a hot air welding device can be selected for welding the overlapping parts of adjacent film sheets. In terms of materials, the hot melt adhesive can be the hot melt adhesive produced by Henkel Corporation that is suitable for bonding with rubber and drainage plate materials; the PE sealing film is laid in sections according to the grid generated by RTK-GPS positioning; the hot melt adhesive is used for bonding the extended sealing ring of the socket rubber joint to the outer wall of the drainage plate.

[0051] The interference amount of the socket rubber joint and the outer wall of the drainage board in interference fit can be set differently, such as 1 mm to 3 mm, etc.; the determination time for the vacuum degree to be stable can be adjusted, such as 30 minutes, etc. The vacuum pump unit is installed at a position convenient for applying negative pressure to the sealed area; the vacuum degree sensor is installed at a suitable position within the sealed area for measuring the vacuum degree; the socket rubber joint is installed at the connection between the filter pipe and the drainage board.

[0052] The matching relationship between the total air extraction volume of the main vacuum pump unit and the total length of the filter pipe can be adjusted according to the actual engineering situation, such as a certain air extraction volume corresponding to each meter of the filter pipe; the air extraction capacity of the standby pump unit as a proportion of the main pump unit can be 110% or 130%, etc. in addition to 120%; the predetermined time for the regional vacuum degree to continuously be lower than 80 kPa can be set, such as 10 minutes, etc. The main vacuum pump unit is installed at a suitable position on the sealed membrane boundary; the standby pump unit is installed on the carrier of the plug board machine; the vacuum degree sensor is installed at the connection point of the filter pipe; the cloud construction management platform is connected to the vacuum degree sensor through the network to receive data.

[0053] In addition to 300 mm to 400 mm, the thickness of the sand layer can also be selected as 320 mm to 380 mm, etc.; in addition to 0.5 mm to 5 mm, the particle size of the sand grains can also be selected as 1 mm to 4 mm, etc.; in addition to ≥1.7 g / cm³, the dry density of the sand layer can also be ≥1.75 g / cm³, etc.

[0054] In this embodiment, the PE sealed membrane is laid in sections based on RTK-GPS positioning and a continuous weld is formed through hot air welding, which ensures the laying accuracy and sealing effect of the sealed membrane, reduces the possibility of air leakage in the sealed area; the sealed connection method between the socket rubber joint and the drainage board, through hot melt adhesive bonding and interference fit, further enhances the reliability of the sealing structure, ensures good sealing at the exposed end of the drainage board, and prevents air from entering and affecting the drainage effect. The negative pressure is applied by the vacuum pump unit and the sealing is determined to be qualified based on the stability of the vacuum degree, scientifically verifying the effectiveness of the sealing. The main vacuum pump unit is arranged at the sealed membrane boundary and matched with the total length of the filter pipe, and the standby pump unit and the vacuum degree sensor are installed and connected to the cloud construction management platform, realizing real-time monitoring and effective control of the vacuum degree in the sealed area. When the vacuum degree is insufficient, the standby pump unit can be enabled in time, ensuring the stable operation of the drainage system and improving the efficiency of soft soil foundation drainage consolidation. The medium-coarse sand is evenly spread by a loader and the thickness and particle size of the sand layer are controlled, and a vibratory roller is used for compaction and the compactness is detected. Finally, the geotextile is laid to form a stable sand layer protection layer, which not only protects the sealed membrane, but also provides a good foundation for subsequent construction, prevents the damage of the sand layer structure by construction machinery, ensures the stability and durability of the entire drainage system, and improves the quality of the soft soil foundation treatment project.

[0055] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and embodiments. It can be fully applied to various fields suitable for the present invention. For those skilled in the art, additional modifications can be easily achieved. Therefore, without departing from the general concept defined by the claims and the equivalent scope, the present invention is not limited to the specific details and the examples shown and described herein.

Claims

1. Construction method of drainage board, characterized in that, Including: Laying a drainage board positioning grid on the surface of the soft soil foundation to be treated, and using RTK-GPS positioning equipment to control the plane coordinates; Implementing the driving of drainage boards by a crawler type board inserter. A dual-axis inclination sensor is installed on the mast of the board inserter, and the perpendicularity of the mast is adjusted in real time through a hydraulic servo mechanism to make the perpendicularity deviation of the drainage board less than 1.5%; When the depth of the bottom end of the drainage board entering the bearing stratum reaches 500 to 800 mm, stop driving, and the exposed length at the top is reserved at 400 to 500 mm, and the center spacing of adjacent drainage boards is controlled at 0.8 m to 1.2 m; Laying a sealing film in the drainage board area, reserving an exposed end for the drainage board, connecting a filter pipe along the exposed end of the drainage board, and connecting the filter pipe and the drainage board with a socket rubber joint; Installing a vacuum pump unit and connecting a vacuum degree sensor. When the vacuum degree under the film is lower than 80 kPa, automatically start the standby vacuum pump unit; Covering a medium-coarse sand protection layer on the surface of the sealing film, with the sand layer thickness of 300 to 400 mm and the sand grain size of 0.5 mm to 5 mm; 2. The construction method of the drainage board according to claim 1, characterized in that, Dividing the bearing capacity difference area according to the static cone penetration test data of the soft soil foundation, adopting a densification spacing of 0.8 m in the high compressibility area, a spacing of 1.0 m in the medium compressibility area, and a widened spacing of 1.2 m in the low compressibility area; Importing the grid parameters into the RTK-GPS navigation system of the board inserter, receiving satellite signals in real time through a dual-frequency receiver in the traveling direction of the board inserter, and combining the laser elevation scanning data of the foundation surface to generate a three-dimensional construction navigation interface at the vehicle-mounted terminal, and dynamically correcting the plane coordinate deviation to ≤15 mm; After each drainage board is driven by the board inserter, an encrypted data packet including the driving point coordinates, driving time, perpendicularity correction amount and soil layer resistance curve is automatically generated and uploaded to the cloud construction management platform; 3. The drainage board construction method according to claim 2, characterized in that, Carrying out static cone penetration tests in the construction area according to a 10 m×10 m grid to obtain the distribution cloud map of the cone tip resistance value qc; Dividing the foundation into three types of areas according to the qc value: In the high compressibility area, qc≤0.5 MPa, and the drainage boards are arranged in an equilateral triangle with a center spacing of 0.8 m±0.05 m; In the medium compressibility area, 0.5 MPa<qc≤1.0 MPa, and the drainage boards are arranged in a square grid with a center spacing of 1.0 m±0.05 m; In the low compressibility area, qc>1.0 MPa, and the drainage boards are arranged in a plum blossom grid with a center spacing of 1.2 m±0.05 m; 4. The construction method of the drainage board according to claim 2, characterized in that, The board inserter is equipped with a dual-frequency RTK-GPS module and a ground laser scanner. The ground elevation data of the construction point is obtained in real time through the laser scanner, and the crawler settlement compensation amount ΔS is calculated in combination with the data of the inclination sensor of the board inserter. The plane coordinates (X, Y) are solved based on the dual-frequency RTK signal, and the three-dimensional coordinate correction is carried out by superimposing ΔS to generate a dynamic navigation path; When the real-time positioning deviation exceeds the threshold value, trigger the hydraulic servo system of the board inserter to adjust the body position until the deviation value ≤ the set threshold value; 5. The drainage board construction method according to claim 3, characterized in that, Install dual-axis inclination sensors at the top and bottom of the mast of the board inserter, and synchronously collect the inclination angles θ1 and θ2 of the mast in the X / Y axes at a frequency of 200 Hz; Calculate the difference in mast bending deformation Δθ = │θ1 - θ2│. When Δθ ≥ 0.1°, trigger shutdown alarm and generate a mast mechanical fault diagnosis report; Based on the obtained cone tip resistance value qc, set the parameters of the hydraulic servo mechanism according to the following rules: Soft soil layer qc ≤ 0.5 MPa: The response speed of the hydraulic cylinder is set to 0.8 m / s, and the single - correction stroke ≤ 5 mm; Hard soil layer qc > 0.5 MPa: The response speed of the hydraulic cylinder is set to 1.2 m / s, and the single - correction stroke ≤ 3 mm; Based on the real - time inclination angles θ1 and θ2, calculate the target correction direction and stroke, control the action of the hydraulic servo mechanism, and converge the mast verticality deviation to ≤ 1.5% within 0.5 seconds.

6. The construction method of the drainage board according to claim 5, characterized in that, Synchronously measure data through the dual - axis inclination sensors at the top and bottom of the mast to construct a mast spatial offset model: Convert the X / Y - axis inclination angles of the top sensor into horizontal offset amounts based on the effective height of the mast, and calculate the local offset components of the X / Y - axis inclination angles of the bottom sensor according to its installation position; By comparing the vector synthesis results of the top and bottom offset amounts, when the comprehensive offset amount reaches 1.5% of the effective height of the mast, perform three - level correction: Coarse - adjustment stage: Based on the classification of the tilt - angle phase difference and the soil layer qc value, dynamically adjust the hydraulic cylinder propulsion speed; Fine - adjustment stage: Combine the mast vibration historical data to predict the motion trajectory and achieve millimeter - level stroke correction through feed - forward compensation; Locking stage: Call the laser scanning device of the vibroflot to verify the verticality. When the measured values for three consecutive times are all lower than 1.5%, trigger the self - locking of the hydraulic system.

7. The drainage board construction method according to claim 6, characterized in that, For highly compressible areas, the driving depth is set to 800 mm ± 50 mm, and the exposed length at the top is reserved as 500 mm ± 20 mm; For moderately compressible areas, the driving depth is set to 650 mm ± 50 mm, and the exposed length at the top is reserved as 450 mm ± 20 mm; For low - compressibility areas, the driving depth is set to 500 mm ± 50 mm, and the exposed length at the top is reserved as 400 mm ± 20 mm; When the penetration resistance of the vibroflot reaches 120% of the qc threshold of the current area, stop driving.

8. The drainage board construction method according to claim 3, characterized in that Based on the grid generated by RTK - GPS positioning, lay the PE sealing film in sections, and form continuous welds at the overlapping joints of adjacent film sheets through hot - air welding equipment; The extended sealing ring of the socket - type rubber joint is bonded to the outer wall of the drainage board through hot - melt adhesive to form a sealing structure, forming a sealing structure that wraps the exposed end of the drainage board; The socket - type rubber joint has an interference fit with the outer wall of the drainage board; After sealing, apply negative pressure through a vacuum pump unit. When the vacuum degree data is stable above 80 kPa, it is determined that the sealing is qualified.

9. The construction method of the drainage board according to claim 8, characterized in that, Install the main vacuum pump unit at the boundary of the sealing film, and its total air extraction volume matches the total length of the filter pipes; install a standby pump unit on the vibroflot carrier, and the air extraction capacity is 120% of that of the main pump unit; Install a vacuum - degree sensor at the filter - pipe connection point, with a measuring range of 0 - 100 kPa, and upload the data to the cloud construction management platform in real time; When the regional vacuum degree is continuously lower than 80 kPa for a predetermined time, automatically activate the standby pump unit.

10. The drainage board construction method according to claim 9, characterized in that, Use a loader to evenly spread medium - coarse sand, with the sand layer thickness controlled between 300 mm and 400 mm, and the sand particle size between 0.5 mm and 5 mm; Use a vibratory roller to compact the sand layer reciprocally for 3 - 5 passes. After compaction, use the cutting ring method to detect the density of the sand layer, and control the dry density ≥ 1.7 g / cm³; Lay geotextile on the surface of the sand layer to prevent the subsequent construction machinery from directly crushing and damaging the structure of the sand layer.

Images