CN104990812A - Meadow shearing force in-situ test method and device - Google Patents

Abstract

The invention belongs to the field of grassland ecological improvement, and in particular relates to an in-situ shear force testing method and device for the grassland soil-root complex structure. According to the requirement of the measured depth, the executive shearing device is forced to penetrate vertically from the surface of the grass into the soil layer at the depth to be measured; after penetrating to the depth to be measured, the executive shearing device is driven to rotate circumferentially, so that the soil within the depth- The root complex structure undergoes shear failure on the acting surface interacting with the performing shearing device until the soil-root complex structure is destroyed, by determining the effective The torque peak value is used to calculate the relevant parameters of the shear strength and shear characteristics of the soil layer at the depth to be measured in the grassland under natural conditions. The invention has strong adaptability, can directly acquire data, is flexible in operation, and solves the problems of data deviation caused by indoor testing of undisturbed soil after traditional manual sampling and laborious sampling caused by high firmness of grassland soil.

Description

A method and device for in-situ testing of grassland shear force

technical field

The invention belongs to the field of grassland ecological improvement, and in particular relates to an in-situ test method and device for grassland shear force aimed at grassland soil-root complex structure.

Background technique

Leymus chinensis is a perennial pasture that mainly reproduces by rhizomes. After many years of growth, the grassland shows a compacted grassland soil with high soil compaction. The subsurface soil of the grassland is compact, and the underground root system interweaves with the soil to form a soil - The characteristics of the root complex structure increase the soil bulk density and firmness of the grassland, and the air and water permeability of the grassland soil decreases, which is not conducive to the growth of the grass root system. The study of the soil-root complex structure and the basic physical characteristics of the compaction layer formed by degraded grassland can provide some basic theoretical support for the design of suitable agricultural machinery for improving degraded grassland.

At present, the research on the shear characteristics of grassland soil is mainly to take soil samples in the field first, and then test the retrieved soil samples in the laboratory with a direct shear instrument or a triaxial tester to measure relevant parameters. Indoor undisturbed soil testing will cause certain data deviations, and the number of samples is relatively large, making the work more cumbersome. The method of in-situ measurement of shear properties can eliminate the work of soil sample collection and sample preparation, quickly determine the shear properties of soil, and at the same time understand the properties of grassland soil, distinguish soil layers, and measure soil shear properties of different soil layers , to reduce the data deviation caused by manual sampling brought back to the indoor determination parameters. At present, the in-situ soil shear characteristics measurement device is mainly used in civil engineering, exploration, water conservancy and hydropower projects, etc., the device specification is relatively large, and the test depth can often reach tens of meters. For the soil layer and soil-root complex structure, there is no related in-situ shear characteristic test method and device.

Contents of the invention

The purpose of the present invention is to provide a method for in-situ testing of grassland shear force, which can measure the shear characteristics of different soil layers of grassland soil-root system complex structure in situ, and directly obtain soil shear parameters in the field, which can be used for the design of grassland cultivation components. Provide some theoretical support for research and development.

Another object of the present invention is to provide an in-situ test device for grassland shear force, which is flexible in operation and can be connected with a tractor to perform field in-situ grassland soil shear test.

In order to achieve the above object, the present invention provides the following technical solutions:

The invention provides a method for in-situ testing of grassland shear stress, the method comprising:

a. Before the test, read and record the idling torque value of the shearing device;

b. According to the requirement of measuring depth, force the executive shearing device to penetrate vertically from the surface of the grass into the soil layer of the depth to be measured, and ensure that the executive shearing device does not rotate during the process of penetrating into the soil layer;

c. After the execution shearing device penetrates to the depth to be measured, the execution shearing device is driven by a mechanical drive device or an electric drive device or manually rotates circumferentially, so that the soil-root complex structure within this depth is in line with the execution shear. Shear failure occurs on the interaction surface of the device until the soil-root complex structure is destroyed, and the maximum torque value of the shearing device is recorded during the process;

d. subtract the idling torque value in step a from the maximum torque value obtained in step c, and obtain the effective torque peak value required for the soil-root complex structure to shear failure until the soil-root complex structure is destroyed;

e. According to the peak value of effective torque, use mathematical calculation methods to calculate the shear strength and parameters related to shear characteristics under the natural conditions of the soil layer at this depth.

The above method also includes:

f. Follow the original rotation direction of the executive shearing device, continue to drive the executive shearing device to rotate 5 to 10 times in the circumferential direction, the rotation time is ≤ 1min, and record the maximum torque value of the executive shearing device during the rotation;

g. Subtract the idling torque value in step a from the maximum torque value obtained in step f, and the obtained value is the effective torque peak value of the shear strength of the remolded soil in situ on the grassland.

In the step c, the shearing device is rotated circumferentially at a rotation speed of 0.05-0.21 rad/min; the time from the shearing device penetrating into the required depth soil layer to the start of the torsion measurement is ≤ 5 minutes.

The present invention provides an in-situ test device for grassland shear force, which includes a frame 1, a shear actuator 2, a torsion shaft 3, a fixed shaft 7, a hydraulic cylinder 10 and a digital display torque wrench 16, wherein,

The hydraulic cylinder 10 is fixed on the top of the frame 1; the upper end of the fixed shaft 7 is connected with the hydraulic rod of the hydraulic cylinder 10 by means of a thread pair, and the lower end of the fixed shaft 7 is connected with the upper end of the torsion shaft 3; the lower end of the torsion shaft 3 is connected with the shear actuator 2 Connected by thread pair;

The shearing actuator 2 includes a vertical shearing plate 13, a transverse shearing plate 14 and a support shaft 15;

Both sides of the middle part of the torsion shaft 3 are milled with planes of a certain width, which match with the clamping end of the digital display torque wrench 16 .

The device also includes a suspension frame 11, the suspension frame 11 is provided with a standard three-point suspension point, and is connected with the rear suspension of the tractor through a three-point suspension mode, and the suspension frame 11 is connected with the frame 1.

The vertical shear plate 13 and the transverse shear plate 14 are fixed on the bottom of the support shaft 15, the length H of the vertical shear plate 13 and the transverse shear plate 14 and the radius R of the circular section formed by the circumferential rotation of the vertical shear plate 13 and the transverse shear plate 14 The ratio ranges from 2 to 8.5; the support shaft 15 is provided with a plurality of scale lines at fixed intervals along the axial direction.

The lower end of the fixed shaft 7 has a stepped hole with a certain depth, and is connected to the upper end of the torsion shaft 3 through the thrust bearing 6, the deep groove ball bearing 5 and the spring stop ring 4.

The above-mentioned grassland shear force in situ test method of the grass shear force in situ test device, the method comprises the following steps:

a. Before the test, the in-situ test device for grass shear force is connected to the tractor through a three-point suspension, and the bottom of the frame 1 is located above the grass and at a certain distance; the torque wrench 16 is used to rotate the torsion shaft 3 in a circumferential direction, and record the number The idling torque value of the torque wrench 16 is the torque value generated by the frictional force or other forces between the internal parts of the device;

b. Operate the tractor to control the three-point suspension to lower the grassland shear force in-situ test device. When the bottom of the frame 1 is completely in contact with the grassland surface, it stops descending. After operating the tractor, the hydraulic system is output, and the hydraulic rod in the hydraulic cylinder 10 is controlled to stretch out to drive The fixed shaft 7, the torsion shaft 3, and the shearing actuator 2 move downward vertically. When the shearing actuator 2 penetrates into the grassland soil layer, it continues to move until it reaches a predetermined depth. After operating the tractor, the output hydraulic system makes the hydraulic pressure of the hydraulic cylinder 10 The rod stops moving, and it is ensured that the shear actuator 2 does not rotate during the process of penetrating into the soil layer;

c. Pull the digital display torque wrench 16 to drive the torsion shaft 3 to rotate in the circumferential direction, so that the soil-root complex structure within this depth will fail to shear on the action surface interacting with the shearing device until the soil-root system The structure of the complex is damaged, and the maximum value of the digital display torque wrench 16 is recorded during the rotation;

d. subtract the torque value of step a idling from the maximum value of the digital display torque wrench 16 obtained in step c, to obtain the effective torque peak value required for shear failure within the depth range of the soil layer where the shear actuator 2 is located;

e. According to the peak value of effective torque, use mathematical calculation methods to calculate the shear strength and parameters related to shear characteristics under the natural conditions of the soil layer at this depth.

The above method also includes:

f. Continue to drive the shearing actuator 2 to rotate 5 to 10 times in the circumferential direction along the original rotation direction of the shearing actuator, and the rotation time is ≤1min. During the rotation, record the maximum torque value of the shearing actuator 2;

g. Subtract the idling torque value in step a from the maximum torque value obtained in step f, and the obtained value is the effective torque peak value of the shear strength of the remolded soil in situ on the grassland.

Compared with prior art, the beneficial effect of the present invention is:

The invention is connected with a tractor to test the shear force of grassland soil in situ in the field. It has strong adaptability, can directly obtain data, and is flexible in operation. The problem of laborious sampling caused by high

Description of drawings

Figure 1 is the front view of the in-situ shear test device

Figure 2 is the left view of the in-situ shear test device

Figure 3 Front view of the hanger

Figure 4 isometric side view of the device after removing the suspension bracket

Figure 5 is a partial enlarged view of the connection between the torsion shaft and the fixed shaft

Figure 6 is a bottom view of the cutting actuator

Figure 7 is a front view of the cutting actuator

The reference signs therein are:

1 Rack 2 Shear actuator

3 Torsion shaft 4 Spring stop ring

5 deep groove ball bearing 6 thrust bearing

7 Fixed shaft 8 Rib plate

9 fixing bolt 10 hydraulic cylinder

11 Suspension frame 12 Connecting bolts

13 vertical shear plate 14 horizontal shear plate

15 Support shaft 16 Digital display torque wrench

H Vertical and transverse shear plate length

R the radius of the circular section formed by the circumferential rotation of the vertical and transverse shear plates along the axis

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

A kind of in-situ test method of grassland shear force of the present invention is applied to test the shear strength of grassland undisturbed soil-root complex structure, and the method comprises:

a. Before the test, read and record the idling torque value of the shearing device, which is the torque value generated by the friction force or other forces between the internal parts of the device;

b. According to the requirement of measuring depth, force the executive shearing device to penetrate vertically from the surface of the grass into the soil layer of the depth to be measured, and ensure that the executive shearing device does not rotate during the process of penetrating into the soil layer;

c. After the execution shearing device penetrates to the depth to be measured, the execution shearing device is driven by a mechanical drive device or an electric drive device or manually rotates circumferentially, so that the soil-root complex structure within this depth is in line with the execution shear. Shear failure occurs on the interaction surface of the device until the soil-root complex structure is destroyed, and the maximum torque value of the shearing device is recorded during the process;

d. subtract the idling torque value in step a from the maximum torque value obtained in step c, to obtain the effective torque peak value required for the soil-root complex structure to shear failure until the soil-root complex structure is destroyed;

e. According to the peak value of effective torque, use mathematical calculation methods to calculate the shear strength and parameters related to shear characteristics under the natural conditions of the soil layer at this depth.

The method can also be applied to test the shear strength of in-situ remolded soil for grassland, the method further includes:

f. Follow the original rotation direction of the executive shearing device, continue to drive the executive shearing device to rotate 5 to 10 times in the circumferential direction, the rotation time is ≤ 1min, and record the maximum torque value of the executive shearing device during the rotation;

g. Subtract the idling torque value in step a from the maximum torque value obtained in step f, and the obtained value is the effective torque peak value of the shear strength of the remolded soil in situ on the grassland.

Preferably, in the step c, the shearing device rotates circumferentially at a rotation speed of 0.05-0.21 rad/min; the time from the shearing device penetrating into the soil layer at a required depth to the start of the torsion measurement is ≤ 5 minutes.

As shown in Figure 1 and Figure 2, they are the front view and the left view of the in-situ test device for grass shear force, respectively. The in-situ test device for grass shear force includes a frame 1 , a suspension frame 11 , a shear actuator 2 , a torsion shaft 3 , a fixed shaft 7 , a hydraulic cylinder 10 and a digital display torque wrench 16 . Wherein, as shown in Figure 3, the suspension frame 11 is provided with standard three-point suspension points, adopts the mode of three-point suspension to be connected with the rear suspension of the tractor, and the frame 1 is connected with the suspension frame 11 by connecting bolts 12; as shown in Figure 4, The hydraulic cylinder 10 is fixed on the top of the frame 1 through the fixing bolt 9;

As shown in Figure 5, the lower end of the fixed shaft 7 is provided with a stepped hole of a certain depth; the torsion shaft 3 is located below the fixed shaft 7, and the upper end of the torsion shaft 3 is connected to the fixed shaft by a thrust bearing 6, a deep groove ball bearing 5 and a spring stop ring 4. The lower end of 7 is connected, and the lower end of the torsion shaft 3 is connected with the shearing actuator 2 through a thread pair; the shearing actuator 2 is located at the bottom of the device. Both sides of the middle part of the torsion shaft 3 are milled with planes of a certain width, which match with the clamping end of the digital display torque wrench 16 .

The frame 1 is welded by section steel, and the top is reinforced by ribs 8 .

The oil inlet and the oil outlet of the hydraulic cylinder 10 are connected with the hydraulic output end of the tractor through hydraulic pipes.

6 and 7 are a bottom view and a front view of the shearing actuator 2, respectively. Described shear execution device 2 comprises vertical shear plate 13, transverse shear plate 14 and support shaft 15; Wherein vertical shear plate 13 and transverse shear plate 14 are fixedly connected to support shaft 15 bottoms, vertical shear The ratio of the length H of the plate 13 and the transverse shear plate 14 to the radius R of the circular section formed by the circumferential rotation along the axis ranges from 2 to 8.5;

The support shaft 15 is provided with a plurality of scale lines at fixed intervals along the axial direction.

Use a kind of grassland shear force in-situ test device, be applied to test the shear strength of grassland undisturbed soil-root complex structure, the method is as follows:

a. Before the test, the in-situ test device for grass shear force is connected to the tractor through a three-point suspension, and the bottom of the frame 1 is located above the grass and at a certain distance; the torque wrench 16 is used to rotate the torsion shaft 3 in a circumferential direction, and record the number The idling torque value of the torque wrench 16 is the torque value generated by the frictional force or other forces between the internal parts of the device;

b. Operate the tractor to control the three-point suspension to lower the grassland shear force in-situ test device. When the bottom of the frame 1 is completely in contact with the grassland surface, it stops descending. After operating the tractor, the hydraulic system is output, and the hydraulic rod in the hydraulic cylinder 10 is controlled to stretch out to drive The fixed shaft 7, the torsion shaft 3, and the shearing actuator 2 move downward vertically. When the shearing actuator 2 penetrates into the grassland soil layer, it continues to move until it reaches a predetermined depth. After operating the tractor, the output hydraulic system makes the hydraulic pressure of the hydraulic cylinder 10 The rod stops moving, and it is ensured that the shear actuator 2 does not rotate during the process of penetrating into the soil layer;

c. Pull the digital display torque wrench 16 to drive the torsion shaft 3 to rotate in the circumferential direction, so that the soil-root complex structure within this depth will fail to shear on the action surface interacting with the shearing device until the soil-root system The structure of the complex is damaged, and the maximum value of the digital display torque wrench 16 is recorded during the rotation;

d. subtract the torque value of step a idling from the maximum value of the digital display torque wrench 16 obtained in step c, to obtain the effective torque peak value required for shear failure within the depth range of the soil layer where the shear actuator 2 is located;

e. According to the peak value of effective torque, use mathematical calculation methods to calculate the shear strength and parameters related to shear characteristics under the natural conditions of the soil layer at this depth.

The method can also be applied to test the shear strength of in-situ remolded soil for grassland, the method further includes:

f. Follow the original rotation direction of the shearing actuator 2, continue to drive the shearing actuator 2 to rotate 5 to 10 times in the circumferential direction, the rotation time is ≤ 1min, and record the maximum torque value of the shearing actuator 2 during the rotation;

g. Subtract the idling torque value in step a from the maximum torque value obtained in step f, and the obtained value is the effective torque peak value of the shear strength of the remolded soil in situ on the grassland.

Claims (9)

1. a meadow shearing force home position testing method, is characterized in that:

The method comprises:

A., before test, read and record the torque value performing shear idle running;

B. according to mensuration depth requirements, force vertical injection to the soil layer of the degree of depth to be measured from surface, meadow execution shear, in injection soil layer process, guarantee that performing shear does not rotate;

C. after performing shear injection to the degree of depth to be measured, by mechanical actuation device or Vidacare corp or drive manually and perform shear and rotate in a circumferential direction, make the termite live in soil structure in this degree of depth with execution shear interactional acting surface on there is shear fails, until termite live in soil structural failure, in process, record performs the maximum torque of shear;

D. step c gained maximum torque is deducted idling torque value in step a, namely obtain making termite live in soil structure generation shear fails until termite live in soil structural failure time required effective torque peak value;

E. according to effective torque peak value, mathematic calculation is used to calculate shearing strength under these degree of depth soil layer natural conditions and the relevant parameter of shear property.

2. meadow according to claim 1 shearing force home position testing method, is characterized in that:

Described method also comprises:

F. along performing the original rotation direction of shear, continuing to drive and perform shear and to rotate in a circumferential direction 5 ~ 10 circles, rotational time≤1min, in rotary course, record performs the maximum torque of shear;

G. step f gained maximum torque is deducted the idling torque value in step a, the value obtained is the effective torque peak value that meadow original position reinvents soil classifiction.

3. meadow according to claim 1 shearing force home position testing method, is characterized in that: in described step c, performs shear and rotates in a circumferential direction with the rotational speed of 0.05 ~ 0.21rad/min; From perform shear injection to desired depth soil layer to carry out reversing measure time≤5min.

4. a meadow shearing force in-situ testing device, is characterized in that:

Described device comprises frame (1), shears actuating unit (2), torsion shaft (3), stationary shaft (7), hydraulic cylinder (10) and Digital Electronic Torque Wrench (16), wherein,

Hydraulic cylinder (10) is fixed on the top of frame (1); Stationary shaft (7) upper end adopts the mode of screw thread pair to be connected with the hydraulic stem of hydraulic cylinder (10), and stationary shaft (7) lower end is connected with torsion shaft (3) upper end; Torsion shaft (3) lower end is connected by screw thread pair with shearing actuating unit (2);

Described shearing actuating unit (2) comprises vertical shearing plate (13), Transverse Shear cutting plate (14) and back shaft (15);

Both sides, described torsion shaft (3) middle part are milled with the plane of one fixed width, match with the bare terminal end of Digital Electronic Torque Wrench (16).

5. meadow according to claim 4 shearing force in-situ testing device, it is characterized in that: described device also comprises hanger bracket (11), hanger bracket (11) is provided with standard trifilar suspension point, be connected with tractor rear-mounted by the mode of trifilar suspension, hanger bracket (11) is connected with frame (1).

6. meadow according to claim 4 shearing force in-situ testing device, it is characterized in that: described vertical shearing plate (13) and Transverse Shear cutting plate (14) are fixed in the bottom of back shaft (15), the length H of vertical shearing plate (13) and Transverse Shear cutting plate (14) is 2 ~ 8.5 with it along the rotate in a circumferential direction scope of ratio of the circular section radius R formed of axis; Described back shaft (15) is provided with multiple scale line with constant spacing vertically.

7. meadow according to claim 4 shearing force in-situ testing device, is characterized in that:

Stationary shaft (7) lower end has the shoulder hole of certain depth, is connected with spring baffle ring (4) by thrust bearing (6), deep groove ball bearing (5) with torsion shaft (3) upper end.

8. utilize the meadow shearing force home position testing method of the meadow shearing force in-situ testing device as described in one of claim 4-7, it is characterized in that:

Described method comprises the steps:

A. before test, be connected by meadow shearing force in-situ testing device by trifilar suspension with tractor, frame (1) bottom to be positioned at above meadow and in a distance; Rotate torsion shaft (3) by Digital Electronic Torque Wrench (16) to rotate in a circumferential direction, record Digital Electronic Torque Wrench (16) torque value that dallies, be the torque value that friction force between the inner each parts of device or other power produce;

B. operate tractor control trifilar suspension meadow shearing force in-situ testing device is declined, frame (1) bottom completely and meadow surface contact time stop declining, output hydraulic pressure system after operation tractor, in hydraulic control cylinder (10), hydraulic stem stretches out, drive stationary shaft (7), torsion shaft (3) and shearing actuating unit (2) vertical ground move downward, when the follow-up reforwarding of shearing actuating unit (2) injection meadow soil layer is moved until output hydraulic pressure system makes the hydraulic stem stop motion of hydraulic cylinder (10) after operating tractor after reaching predetermined depth, guarantee in injection soil layer process that shearing actuating unit (2) does not rotate,

C. Digital Electronic Torque Wrench (16) is pulled, torsion shaft (3) is driven to rotate in a circumferential direction, make the termite live in soil structure in this degree of depth with execution shear interactional acting surface on there is shear fails, until termite live in soil structural failure, in rotary course, record the maximal value of Digital Electronic Torque Wrench (16);

D. the maximal value of step c gained Digital Electronic Torque Wrench (16) is deducted the torque value of step a idle running, effective torque peak value required when obtaining shearing the shear failure within the scope of the soil depth of actuating unit (2) place;

E. according to effective torque peak value, mathematic calculation is used to calculate shearing strength under these degree of depth soil layer natural conditions and the relevant parameter of shear property.

9. meadow according to claim 8 shearing force home position testing method, is characterized in that:

Described method also comprises:

F. along performing the original rotation direction of shear, continue to drive and shear actuating unit (2) and to rotate in a circumferential direction 5 ~ 10 circles, rotational time≤1min, in rotary course, the maximum torque of actuating unit (2) sheared in record;

G. step f gained maximum torque is deducted the idling torque value in step a, the value obtained is the effective torque peak value that meadow original position reinvents soil classifiction.