A non-destructive testing method for tree anchoring force based on trunk wind sway deformation

Abstract

The present application provides a kind of tree anchoring force nondestructive testing method based on trunk wind swing deformation, comprising: installing trunk inclination and trunk strain sensor, obtaining trunk inclination and trunk strain information;Data fusion is carried out to four strain sensors installed at different positions of the trunk, to obtain the trunk circumferential strain distribution, the position of the bending neutral plane of the trunk, the height of the equivalent action point of wind force and the equivalent wind load;Based on the inclination of the root of the trunk and the equivalent wind load on the tree, the anchoring force of the tree is calculated by the calculation formula of the anchoring force of the tree.The present application overcomes the shortcomings of existing measurement technology, and the test method is simple, the anchoring force of the tree can be obtained, and is used for garden ancient and famous trees, street trees and wind resistance and anti-falling ability analysis of forest trees.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of non-destructive testing of trees, and relates to a tree anchoring force non-destructive testing method which is convenient to operate and high in detection precision. BACKGROUND

[0002] The tree anchoring force refers to the maximum anti-overturning moment that can be provided by the tree roots under the action of external force (moment). In the evaluation system of tree safety, tree trunk breakage and tree root uprooting are the two most important evaluation bases. In considering the process of tree root uprooting, measuring the tree anchoring force is the most basic prerequisite.

[0003] There are many factors affecting the tree anchoring force, such as soil water content, soil composition, soil freezing condition, tree root depth, tree root breadth and tree species. If the above factors are considered, it will lead to heavy work task, large amount of data and difficulty in obtaining the real anchoring force value.

[0004] In order to avoid the above problems, the present application provides a new non-destructive testing method. The tree deflects under the action of wind load, and there is a certain quantitative relationship among the root deflection angle, the wind load and the tree anchoring force. According to the cantilever beam assumption, the wind load on the tree is obtained from the strain of the trunk, and the tree anchoring force can be simply, conveniently, quickly and accurately detected by combining the root deflection angle of the trunk, which is of great significance to the safety of the tree. SUMMARY

[0005] In order to solve the problem of detecting the tree anchoring force, the present application provides a tree anchoring force non-destructive testing method based on the deformation of trunk wind swing.

[0006] The technical scheme adopted by the present application to solve the technical problem is: a tree anchoring force non-destructive testing method based on the deformation of trunk wind swing. The detection method comprises sensor installation and related data processing, wherein the sensor installation method is characterized by: taking four strain sensors and one inclination sensor as the main body; among the four strain sensors, strain sensor 1, strain sensor 2 and strain sensor 3 are installed on the same height horizontal cross section of the trunk, generally near the cross section shape of the regular place near the breast diameter, and the spacing between the three sensors needs to be approximately equal; strain sensor 4 is installed about 20 cm below strain sensor 1; the inclination sensor is installed at the root of the trunk about 10-20 cm from the ground; the collected signals of the strain sensor and the inclination sensor are transmitted to the computer through Bluetooth.

[0007] Specifically, the strain sensor has fixed clamping grooves at both ends, which facilitates installation at different heights of the trunk.

[0008] The inclination sensor has a self-installed base, which facilitates installation at the root of the trunk.

[0009] The strain sensor and the inclination sensor are both battery-powered, and data transmission is by Bluetooth, facilitating field use.

[0010] The data processing algorithm comprises a strain sensor data fusion algorithm and a tree anchoring force calculation algorithm. The strain sensor data fusion algorithm takes a cantilever beam model as a basic assumption, the data of the strain sensor 1, the strain sensor 2 and the strain sensor 3 are used to obtain a bending neutral plane when the trunk is bent, the normal of the bending neutral plane is the wind direction, the data of the strain sensor 1, the strain sensor 2 and the strain sensor 3 and the distance thereof to the bending neutral plane are used to determine the trunk circumferential strain distribution, and the proportional relationship between the strain sensor 4 and the strain sensor 1 is used to determine the equivalent wind force action point height and the equivalent wind load. The tree anchoring force calculation algorithm is a specific quintic polynomial of the equivalent wind load borne by the tree divided by the windward side trunk root inclination.

[0011] According to the nondestructive detection method of the tree anchoring force provided by the application, the strain sensor, the inclination sensor and the related algorithm are used, and the method is characterized in that: wind is used to load the tree, a cantilever beam model is taken as a basic assumption, four strain sensors are used to determine the wind load borne by the tree through an algorithm, and the tree anchoring force is solved in combination with the trunk root inclination and the wind load borne by the tree.

[0012] The detection method is as follows:

[0013] (1) The strain sensor and the inclination sensor are installed on the trunk of the tree to be detected, and the positions of the sensors on the trunk are recorded.

[0014] (2) The tree is monitored for a long time, and the trunk tensile strain and the trunk root inclination of the tree under the action of wind are recorded.

[0015] (3) The data of the strain sensor 1, the strain sensor 2 and the strain sensor 3 are used to obtain the bending neutral plane when the trunk is bent, the data of the strain sensor 1, the strain sensor 2 and the strain sensor 3 and the distance thereof to the bending neutral plane are used to determine the trunk circumferential strain distribution, the proportional relationship between the sensor 4 and the strain sensor 1 is used to determine the equivalent wind force action point height and the equivalent wind load, the data of the trunk inclination sensor are used to obtain the windward side trunk root inclination, and the tree anchoring force is calculated by a specific quintic polynomial of the equivalent wind load divided by the windward side trunk root inclination.

[0016] The application has the advantages that the anchoring force of the tree can be determined by detecting the tree under the action of wind for a short time, the installation is convenient, the operation is simple, and the design is ingenious. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Shown is a schematic diagram of the sensor installation of the present invention.

[0018] Figure 2 Shown is a top view of the installation orientation of four strain sensors.

[0019] Figure 3 The figure shows the installation orientation of the tilt sensor.

[0020] Figure 4 Shown is the measurement flow chart.

[0021] The specific numbers and symbols in the figure are explained as follows:

[0022] 1. Strain sensor 2. Strain sensor 3. Strain sensor 4. Strain sensor (Note: The four strain sensors have the same specifications and range, but are numbered differently due to their different installation positions) 5. Inclination sensor 6. Trunk DETAILED DESCRIPTION

[0023] In order to make the technical solution of the present invention more clear, the present invention will be further described below with reference to specific embodiments of the drawings.

[0024] like Figures 1-3 As shown, the present invention describes a non-destructive testing method for tree anchoring force based on wind-induced deformation of tree trunks, which is characterized by: using a strain sensor 1, a strain sensor 2, a strain sensor 3, a strain sensor 4, and an inclination sensor 5 as additional measurement units; the strain sensors 1-4 are fixedly connected to the trunk 6 via two iron nails; the inclination sensor 5 is fixedly connected to the bottom of the trunk 6 via a base; and all the sensors transmit data via Bluetooth.

[0025] In this embodiment, both ends of the strain sensors 1 - 4 are provided with fixing slots, which facilitate installation at different heights of the tree trunk 6 .

[0026] In this embodiment, the tilt sensor 5 has a built-in mounting base, which is convenient for installation at the root of the tree trunk 6 .

[0027] In this embodiment, the strain sensors 1-4 and the tilt sensor 5 are all powered by batteries, and the data transmission method is Bluetooth transmission, which is convenient for field use.

[0028] In this embodiment, the detection method is as follows Figure 4 As shown, it is divided into the following steps:

[0029] Step 1: Equipment installation. Figure 1 As shown, each sensor is installed in sequence according to the local prevailing wind direction;

[0030] Step two: input basic parameters. Open the software, set the tree information, including project name, project number, tree name, tree number and tree location; input basic parameters, including tree diameter d (mm), height of inclination sensor from ground h1 (cm), height of strain sensor 1 from ground h2 (m), height of strain sensor 4 from ground h3 (m). Take the geometric center of the trunk as the origin, and the north as the y axis to establish the coordinate system, and determine the coordinates of strain sensor 1 on the installed cross section (x1, y1), the coordinates of strain sensor 2 on the installed cross section (x2, y2), the coordinates of strain sensor 3 on the installed cross section (x3, y3), and the coordinates of strain sensor 4 projected on the cross section where strain sensor 1 is installed (x4, y4).

[0031] Step three: detection process. Install the sensor under relatively windless conditions, and zero the sensor. When zeroing, click the "clear" icon, and the four sensors need to be in a force-free state for about 10s under windless conditions, then the sensor displays that it has been cleared, and detection can be performed. Then set continuous sampling, click the "start measurement" icon, and stop detection after the tree deflects obviously under the action of wind. Save the collected data after detection is completed.

[0032] Step four: data processing. The strains measured by strain sensors 1-4 are ε1-ε4, and the inclination measured by the inclination sensor is β. According to Figure 2 the inclination of the inclination sensor, the inclination of the windward side of the trunk root is calculated by the formula α = 90°-arccos(|cos(θ)sin(β)|). As shown in Figure 3 , assuming the equation of the bending neutral surface is y=kx+b, the parameters k and b are determined by the following equation set:

[0033]

[0034] The bending moment of the trunk at strain sensor 1 is The bending moment of the trunk at strain sensor 4 is The aforementioned elastic modulus E is obtained by looking up the table, and I1 and I4 are obtained according to the cross-sectional area of the trunk at the positions of strain sensors 1 and 4. According to the installation heights of strain sensors 1 and 4, the equivalent wind load M is calculated by the formula , and finally the anchoring force T of the tree is calculated by the formula

[0035]

Claims

1. 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