Handheld constant-stiffness ring shear apparatus and method for using same

Patent metadata

Field	Value
Publication number	US-10168263-B2
Application number	US-201615529815-A
Country	US
Kind code	B2
Filing date	Mar 30, 2016
Priority date	Apr 29, 2015
Publication date	Jan 1, 2019
Grant date	Jan 1, 2019

Abstract

A handheld constant-stiffness ring shear apparatus has a base and an annular rigid frame arranged on the base in a sleeved mode. An upper cover is buckled to the top of the rigid frame, a pressure transmission plate is fixed to the upper portion of the upper cover, and a rotary shaft is perpendicularly arranged in the center of the base. The rotary shaft penetrates through the pressure transmission plate and is fixed to the pressure transmission plate. A spanner is fixed to the top end of the rotary shaft, and a digital display instrument is embedded in the spanner. The handheld constant-stiffness ring shear apparatus is convenient to carry, easy to operate, economical and practical, and can be used for measuring the volume chance of a soil sample at a field location under the constant-stiffness condition in the shear force resisting and shearing process.

First claim

What is claimed is:

1. A handheld constant-stiffness ring shear apparatus, comprising a base and an annular rigid frame arranged on the base in a sleeved mode, characterized in that an annular upper cover is buckled to the top of the rigid frame, a pressure transmission plate is fixed to the upper portion of the upper cover, a rotary shaft is perpendicularly arranged in the center of the base, the rotary shaft penetrates through the pressure transmission plate and is fixed to the pressure transmission plate, a spanner is fixed to the top end of the rotary shaft, and a digital display instrument is embedded in the spanner; a spring support is fixed to the side wall of the base, spring guide rods are perpendicularly fixed under the spring support, the upper ends of the spring guide rods are sleeved with limiting nuts, the portions, below the limiting nuts, of the spring guide rods are sleeved with springs, and sliding blocks are pressed to the lower ends of the springs and arranged on the pressure transmission plate; a first clamp is connected between the upper ends of the springs and the pressure transmission plate, and a first dial indicator is mounted on the first clamp; a dial indicator support is further fixed to the side wall of the base and connected with the pressure transmission plate through a second clamp, and a second dial indicator is mounted on the second clamp; the overall dimensions of the handheld constant-stiffness ring shear apparatus are 200 mm*120* mm*240 mm.

2. The handheld constant-stiffness ring shear apparatus according to claim 1 , characterized in that the rotary shaft is arranged in a bearing in a sleeved mode, and the bearing is perpendicularly fixed to the center of the base.

3. The handheld constant-stiffness ring shear apparatus according to claim 2 , characterized in that limiting piles are arranged at the bottom of the rigid frame, limiting grooves are formed on the base, and the limiting piles are located in the limiting grooves.

4. The handheld constant-stiffness ring shear apparatus according to claim 3 , characterized in that a handle is arranged on the outer side of the base.

5. The handheld constant-stiffness ring shear apparatus according to claim 4 , characterized in that round spacers are arranged on the upper portions of the sliding blocks and make contact with the lower ends of the springs.

6. A using method of the handheld constant-stiffness ring shear apparatus according to claim 5 , characterized by comprising the following steps that:
S1, the rigid frame is taken out, and a soil sample is evenly placed into the rigid frame;
after the soil sample is placed into the rigid steel, the surface of the soil sample is scraped flat, the height of the soil sample is made to meet the requirement, and the rigid frame is placed into the base of the apparatus;
S2, the apparatus is covered with the upper cover, the sliding blocks are placed on the pressure transmission plate, and the spacers are placed on the sliding blocks;
S3, the spring support, the spring guide rods, the limiting nuts and the springs are mounted, and it is ensured that the spring spacers connected with the springs are placed on the annular sliding blocks on the pressure transmission plate;
S4, the limiting nuts are adjusted to place the soil sample in a pre-pressed state;
S5, the spring support, the first dial indicator and the first clamp are mounted, and the initial reading of the first dial indicator is recorded; the dial indicator support, the second dial indicator and the second clamp are mounted, and the initial reading of the second dial indicator is recorded;
S6, the handle of the base is held with one hand, a torque is applied with the other hand through the spanner to rotate the rotary shaft, the rotary shaft drives the pressure transmission plate and the upper cover to rotate, and shear stress is generated on the upper surface of the soil sample to shear the soil sample; during the process, the reading of the first dial indicator, the reading of the second dial indicator and the reading of the digital display instrument are recorded;
S7, after the test is ended, the soil sample is removed, and the average shear stress and the average normal stress acting on the soil sample are worked out according to the reading of the first dial indicator, the reading of the second dial indicator and the reading of the digital display instrument.

7. The using method of the handheld constant-stiffness ring shear apparatus according to claim 6 , characterized in that in step S7, the inner diameter and the outer diameter of the annular soil sample are preset to be R 1 and R 2 correspondingly; suppose that the shear stress τ on the soil sample is evenly distributed, the torque M acting on the soil sample can be known according to the reading of the digital display instrument in the loading process, and according to the static balance condition, the average shear stress on the soil sample meets the following formula:

τ
=

3
⁢

⁢
M

2
⁢

⁢

π
⁡

(

R
2
3

-

R
1
3

)

in the formula, τ refers to the average shear stress, M refers to the torque acting on the soil sample, R 1 refers to the inner diameter of the annular soil sample, R 2 refers to the outer diameter of the annular soil sample, and π is 3.14.

8. The using method of the handheld constant-stiffness ring shear apparatus according to claim 6 , characterized in that in step S7, the compression amount x of the springs is obtained through calculation according to the reading of the first dial indicator, and the normal stress F acting on the soil sample meets the following formula:
F=n·k·x
in the formula, F refers to the normal stress, k refers to the stiffness coefficient of the springs, and n refers to the number of the springs;
the average normal stress σ n on the soil sample is worked out by means of the normal stress F according to the following formula:

σ
n

=

F

π
⁡

(

R
2
2

-

R
1
1

)

in the formula, σ n refers to the average normal stress, F refers to the normal stress, R 1 refers to the inner diameter of the annular so

Assignees

• Univ Shenzhen

Inventors

• Su Dong

Classifications

• G01L1/00

  Measuring force or stress, in general (measuring force due to impact G01L5/00) · CPC title

• G01N3/24 Primary

  by applying steady shearing forces (G01N3/26, G01N3/28 take precedence) · CPC title