CN107748369A - A kind of automatic measurement system and its measuring method of soil sample breathing change - Google Patents

Abstract

An automatic measurement system and measurement method for soil sample expansion and contraction changes, the measurement system includes a test bench installed on a supporting chassis, a soil sample to be tested is placed on the test bench, and a laser displacement sensor assembly is arranged above the soil sample to be tested. The laser displacement sensor assembly includes three sets of laser heads distributed on the same height plane, and the three sets of laser heads simultaneously emit laser pulses that are reflected by the soil sample to be tested and received by the laser displacement sensor assembly. During the measurement, according to the time elapsed from sending out the three groups of laser pulses to being received back, the distances between the three groups of laser heads and the surface of the soil sample to be tested are calculated respectively, and then the vertical height between the laser head and the surface of the soil sample to be tested is calculated, combined with The vertical height between the laser head and the surface of the test bench can be calculated to obtain the thickness of the soil sample to be tested. The invention can avoid direct contact with the soil sample to be tested during use, automatically measure the strain change of the soil sample, and greatly improve the detection accuracy and work efficiency.

Description

An automatic measurement system and measurement method for soil sample expansion and contraction changes

technical field

The invention relates to the field of soil sample measurement, in particular to an automatic measurement system and a measurement method for soil sample expansion and contraction changes.

Background technique

The measurement of soil sample expansion and contraction is a common measurement content in engineering and geotechnical tests. Traditional measurement methods use vernier calipers, dilatometers or shrinkage meters to measure the axial displacement of soil to analyze the expansion and contraction of soil samples.

In these methods, the measuring tool must be in contact with the soil sample. Although the contact pressure is not large, for some soft soil samples, it is not allowed to contact the measuring tool with the soil sample, otherwise it will leave impressions or scratches on the surface of the soil sample, affecting measurement accuracy. At the same time, most of the traditional detection methods use manual methods for measurement, which are low in efficiency, time-consuming, labor-intensive and poor in repeatability of measurement points.

Contents of the invention

The object of the present invention is to provide an automatic measurement system for soil sample expansion and contraction changes in view of the above-mentioned problems in the prior art. Swelling and shrinking changes.

In order to achieve the above object, the automatic measurement system for soil sample expansion and contraction of the present invention includes a test bench installed on the support chassis, the soil sample to be tested is placed on the test bench, and a laser displacement sensor assembly is arranged above the soil sample to be tested. The sensor component includes three sets of laser heads distributed on the same height plane. The three sets of laser heads simultaneously emit laser pulses that are reflected by the soil sample to be tested and then received by the laser displacement sensor component; time, calculate the distances between the three groups of laser heads and the surface of the soil sample to be tested respectively, and then calculate the vertical height between the laser head and the surface of the soil sample to be tested, combine the vertical height between the laser head and the surface of the test platform, and then make the difference The thickness of the soil sample to be tested can be obtained.

A support frame is installed on the support chassis, and the laser displacement sensor assembly is arranged above the soil sample to be tested through the support frame.

The laser displacement sensor assembly is connected to the support frame through a height adjustment knob, and the support frame is provided with a highly movable chute that can cooperate with the height adjustment knob.

The laser displacement sensor assembly is integrally connected to the touch screen computer control system.

The touch screen computer control system has a USB interface and a touch screen control button.

The test bench is equipped with a vertical adjustment knob and a horizontal adjustment knob for adjusting its position on the supporting chassis.

The automatic measurement method of soil sample expansion and contraction change of the present invention comprises the following steps:

1) Place the prepared soil sample to be tested on the test bench;

2) Adjust the soil sample to be tested to face the three sets of laser heads, and adjust the height of the laser displacement sensor assembly;

3) Turn on the three sets of laser heads to emit laser pulses to the soil sample to be tested. After the laser pulses are reflected by the soil samples to be tested, they are received by the laser displacement sensor assembly, and the time t elapsed from sending out the laser pulses to being received back is recorded;

4) Calculate the thickness d of the soil sample to be tested according to the following formula:

d=s-h;

In the above formula, h is the vertical height from the laser head to the surface of the soil sample to be tested;

s is the height from the laser head to the surface of the test bench.

The specific calculation method of the h is as follows:

Input θ1, θ2, θ3 (the angle between the laser beam and the vertical line), and put t1, t2, t3 (the time elapsed from the emission of the three laser beams to the return) into the formula:

L1=(v*t1)/2,

L2=(v*t2)/2,

L3=(v*t3)/2, v is the speed of light;

Then bring L1, L2, L3 (the length of the laser beam) into the formula:

a1=L1*sinθ1;

a2=L2*sinθ2;

a3=L3*sinθ3;

b1=L1*cosθ1;

b2=L2*cosθ2;

b3=L3*cosθ3;

1) When b1≠b2 and b1≠b3:

u3=-(a1+b1*u2);

Finally into the formula:

When b1=b2:

u2=(a1*a2+a2*a3+a1*a3)/(a2*(b3-b1));

u3=-(u2*b1+a1);

2) When b1=b3:

u2=(a1*a2+a2*a3+a1*a3)/(a3*(b2-b1));

u3=-(u2*b1+a1);

3) When b1=b2=b3:

h=b1=b2=b3.

Compared with the existing technology, the measurement system of the present invention places the soil sample to be tested on the test platform, and uses three sets of laser heads to aim at the soil sample to be tested to emit laser pulses. After being reflected by the soil sample to be tested, the laser light scatters in all directions , part of the scattered light returns to the laser displacement sensor assembly and is received. According to the time elapsed from the sending out of the laser pulse to the return being received, the distances between the three groups of laser heads and the surface of the soil sample to be tested are calculated respectively, and then the distance between the laser head and the soil sample to be tested is calculated. The vertical height of the sample surface, combined with the vertical height of the laser head and the test platform surface, can get the thickness of the soil sample to be tested after making a difference. The measurement system of the present invention adopts a modular structure, which is safe and reliable, has a high degree of automation, and can be operated remotely. During use, it can avoid direct contact with the soil sample to be tested, and automatically measure the strain change of the soil sample, which greatly improves the detection efficiency. Accuracy and work efficiency, and it is also easy to maintain and replace parts, which provides convenience for saving the cost of use, and is easy to popularize and apply in production and teaching.

Compared with the prior art, compared with the traditional manual method, the measurement method of the present invention can completely overcome the shortcomings of manual detection, reduce the disturbance of the soil sample to be tested, and thus improve the measurement accuracy of the thickness change of the soil sample.

Description of drawings

The whole structure front view of Fig. 1 of the present invention;

The overall structure side view of Fig. 2 of the present invention;

Fig. 3 schematic diagram of working principle of the present invention;

The basic principle flowchart of Fig. 4 of the present invention;

In the drawings: 1-support chassis; 2-connecting bolts; 3-support frame; 4-test bench; 5-longitudinal adjustment knob; 6-level adjustment knob; 7-laser head; 8-laser displacement sensor assembly; 9- Touch screen computer control system; 10-height adjustment knob; 11-height movable chute; 12-USB interface; 13-touch screen control button.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings.

Referring to Figures 1-2, the present invention includes a bracket system, a laser displacement measurement system and a computer data processing system.

The bracket system is composed of a support chassis 1, a support frame 3, and a test bench 4; the laser displacement measurement system is composed of a laser head 7, a laser displacement sensor assembly 8, a height adjustment knob 10, and a height movable chute 11; the computer data processing system is a touch screen Computer control system9. Specifically, the present invention includes a test bench 4 installed on the support chassis 1, a soil sample to be tested is placed on the test bench 4, a laser displacement sensor assembly 8 is arranged above the soil sample to be tested, and the laser displacement sensor assembly 8 includes a USB interface 12 As well as three groups of laser heads 7 distributed on the same height plane, the laser displacement sensor assembly 8 is arranged above the soil sample to be measured through the support frame 3 . A vertical adjustment knob 5 and a horizontal adjustment knob 6 are installed on the test bench 4 . The laser displacement sensor assembly 8 is connected to the support frame 3 through a height adjustment knob 10 , and the support frame 3 is provided with a height movable chute 11 that can cooperate with the height adjustment knob 10 . The laser displacement sensor assembly 8 and the laser head 7 are integrally connected to the touch screen computer control system 9 . The touch screen computer control system 9 has a USB interface 12 and a touch screen control button 13 .

Referring to Figures 3-4, when the present invention is in use, the prepared soil sample to be tested is first placed on the test platform 4 before the test, and the vertical adjustment knob 5 and the horizontal adjustment knob 6 make the soil sample to be tested face the three sets of laser heads 7. Then rotate the height adjustment knob 10 to make the laser displacement sensor assembly 8 be at a suitable height, click the start test button in the touch screen computer control system 9 to obtain data, and then calculate the data such as thickness change and strain rate of the soil sample, and finally Automatic recording and storage.

Click the start button in the touch screen computer control system 9, three groups of rotatable laser heads 7 sequentially emit laser pulses, the laser light is scattered in various directions after being reflected by the target, and part of the scattered light returns to the laser displacement sensor assembly 8 to be received, recorded and processed The time t elapsed from the sending out of the laser pulse to the time when the laser pulse is received back is calculated according to the following formula to calculate the thickness d of the soil sample to be tested:

d=s-h;

In the above formula, h is the vertical height from the laser head to the surface of the soil sample to be tested;

s is the height from the laser head to the surface of the test bench.

The specific calculation method of the h is as follows:

Input θ1, θ2, θ3 (the angle between the laser beam and the vertical line), and put t1, t2, t3 (the time elapsed from the emission of the three laser beams to the return) into the formula:

L1=(v*t1)/2,

L2=(v*t2)/2,

L3=(v*t3)/2, v is the speed of light;

Then bring L1, L2, L3 (the length of the laser beam) into the formula:

a1=L1*sinθ1;

a2=L2*sinθ2;

a3=L3*sinθ3;

b1=L1*cosθ1;

b2=L2*cosθ2;

b3=L3*cosθ3;

1) When b1≠b2 and b1≠b3:

u3=-(a1+b1*u2);

Finally into the formula:

When b1=b2:

u2=(a1*a2+a2*a3+a1*a3)/(a2*(b3-b1));

u3=-(u2*b1+a1);

2) When b1=b3:

u2=(a1*a2+a2*a3+a1*a3)/(a3*(b2-b1));

u3=-(u2*b1+a1);

3) When b1=b2=b3:

h=b1=b2=b3.

Then, through the relevant formulas of the geotechnical test, the axial strain, expansion and contraction ratio and other data of the sample to be tested can be obtained, and finally the results are displayed on the computer touch screen or transmitted to the remote terminal.

Claims (8)

1. A kind of 1. automatic measurement system of soil sample breathing change, it is characterised in that：Including the test in support chassis (1) Platform (4), soil sample to be measured is placed on testboard (4), the top of soil sample to be measured is provided with laser displacement sensor component (8), laser position Displacement sensor component (8) includes three groups of laser heads (7) being distributed in sustained height plane, and three groups of laser heads (7) are launched simultaneously Laser pulse is received after soil sample to be measured reflection by laser displacement sensor component (8)；

   According to three groups of laser pulses be issued to return is received the undergone time, calculate respectively three groups of laser heads (7) and The distance on soil sample surface to be measured, then calculate the vertical height of laser head (7) and soil sample surface to be measured, with reference to laser head (7) with The vertical height on testboard (4) surface, the thickness of soil sample to be measured can be accessed after making the difference.
2. 2. the automatic measurement system of soil sample breathing change according to claim 1, it is characterised in that：Support chassis is pacified on (1) Support frame (3) is filled, laser displacement sensor component (8) is arranged on the top of soil sample to be measured by support frame (3).
3. 3. the automatic measurement system of soil sample breathing change according to claim 1, it is characterised in that：Described laser displacement passes Sensor component (8) is connected by height adjustment knob (10) with support frame (3), and being provided with described support frame (3) can be with The high activity chute (11) that height adjustment knob (10) is engaged.
4. 4. the automatic measurement system of soil sample breathing change according to claim 1, it is characterised in that：Described laser displacement passes Sensor component (8) integral type connection touch screen computer control system (9).
5. 5. the automatic measurement system of soil sample breathing change according to claim 4, it is characterised in that：Described touch screen computer There is USB interface (12) and touch screen control button (13) in control system (9).
6. 6. the automatic measurement system of soil sample breathing change according to claim 1, it is characterised in that：Described testboard (4) On be provided with for adjusting from the longitudinally adjusted knob (5) of position and horizontal adjustment knob (6) in support chassis (1).
7. A kind of 7. survey for the automatic measurement system that soil sample breathing described in any one claim changes in 1-6 based on claim Amount method, it is characterised in that comprise the following steps：

   1) soil sample to be measured made is placed on testboard (4)；

   2) soil sample to be measured is adjusted to three groups of laser heads (7) of face, and adjusts the height of laser displacement sensor component (8)；

   3) three groups of laser heads (7) are opened, are allowed to launch laser pulse to soil sample to be measured, laser pulse reflects by soil sample to be measured Afterwards, received by laser displacement sensor component (8), recording laser pulse is issued to return and is received undergone time t；

   4) soil sample thickness d to be measured is calculated according to the following formula：

   D=s-h；

   In above formula, h is vertical height of the laser head to soil sample surface to be measured；

   S is height of the laser head to testboard surface.
8. 8. measuring method according to claim 7, it is characterised in that the circular of the h is as follows：

   The angle theta 1 of input laser beam and perpendicular bisector, θ 2, θ 3, time t1, t2 that three laser beams are undergone from sending to returning, T3 brings formula into, and solution obtains length L1, L2, L3 of laser beam；

   L1=(v*t1)/2,

   L2=(v*t2)/2,

   L3=(v*t3)/2, v is the light velocity；

   Bring length L1, L2, L3 of laser beam into formula again：

   A1=L1*sin θ 1；

   A2=L2*sin θ 2；

   A3=L3*sin θ 3；

   B1=L1*cos θ 1；

   B2=L2*cos θ 2；

   B3=L3*cos θ 3；

   1) as b1 ≠ b2 and b1 ≠ b3：

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   <mrow> <mi>u</mi> <mn>2</mn> <mo>=</mo> <mfrac> <mrow> <mi>a</mi> <mn>3</mn> <mo>+</mo> <mn>2</mn> <mo>*</mo> <mi>a</mi> <mn>1</mn> <mo>+</mo> <msqrt> <mn>3</mn> </msqrt> <mo>*</mo> <mi>a</mi> <mn>3</mn> <mo>*</mo> <mi>u</mi> <mn>1</mn> </mrow> <mrow> <mn>2</mn> <mo>*</mo> <mrow> <mo>(</mo> <mi>b</mi> <mn>3</mn> <mo>-</mo> <mi>b</mi> <mn>1</mn> <mo>)</mo> </mrow> </mrow> </mfrac> <mo>;</mo> </mrow>

   U3=- (a1+b1*u2)；

   Finally bring formula into：

   <mrow> <mi>h</mi> <mo>=</mo> <mrow> <mo>|</mo> <mrow> <mi>u</mi> <mn>3</mn> </mrow> <mo>|</mo> </mrow> <mo>/</mo> <msqrt> <mrow> <mn>1</mn> <mo>+</mo> <mi>u</mi> <mn>1</mn> <mo>*</mo> <mi>u</mi> <mn>1</mn> <mo>+</mo> <mi>u</mi> <mn>2</mn> <mo>*</mo> <mi>u</mi> <mn>2</mn> </mrow> </msqrt> <mo>;</mo> </mrow>

   As b1=b2：

   <mrow> <mi>u</mi> <mn>1</mn> <mo>=</mo> <mrow> <mo>(</mo> <mi>a</mi> <mn>2</mn> <mo>+</mo> <mn>2</mn> <mo>*</mo> <mi>a</mi> <mn>1</mn> <mo>)</mo> </mrow> <mo>/</mo> <mrow> <mo>(</mo> <msqrt> <mn>3</mn> </msqrt> <mo>*</mo> <mi>a</mi> <mn>2</mn> <mo>)</mo> </mrow> <mo>;</mo> </mrow>

   U2=(a1*a2+a2*a3+a1*a3)/(a2* (b3-b1))；

   U3=- (u2*b1+a1)；

   <mrow> <mi>h</mi> <mo>=</mo> <mrow> <mo>|</mo> <mrow> <mi>u</mi> <mn>3</mn> </mrow> <mo>|</mo> </mrow> <mo>/</mo> <msqrt> <mrow> <mn>1</mn> <mo>+</mo> <mi>u</mi> <mn>1</mn> <mo>*</mo> <mi>u</mi> <mn>1</mn> <mo>+</mo> <mi>u</mi> <mn>2</mn> <mo>*</mo> <mi>u</mi> <mn>2</mn> </mrow> </msqrt> <mo>;</mo> </mrow>

   2) as b1=b3：

   <mrow> <mi>u</mi> <mn>1</mn> <mo>=</mo> <mo>-</mo> <mrow> <mo>(</mo> <mi>a</mi> <mn>3</mn> <mo>+</mo> <mn>2</mn> <mo>*</mo> <mi>a</mi> <mn>1</mn> <mo>)</mo> </mrow> <mo>/</mo> <mo>-</mo> <mrow> <mo>(</mo> <msqrt> <mn>3</mn> </msqrt> <mo>*</mo> <mi>a</mi> <mn>3</mn> <mo>)</mo> </mrow> <mo>;</mo> </mrow>

   U2=(a1*a2+a2*a3+a1*a3)/(a3* (b2-b1))；

   U3=- (u2*b1+a1)；

   <mrow> <mi>h</mi> <mo>=</mo> <mrow> <mo>|</mo> <mrow> <mi>u</mi> <mn>3</mn> </mrow> <mo>|</mo> </mrow> <mo>/</mo> <msqrt> <mrow> <mn>1</mn> <mo>+</mo> <mi>u</mi> <mn>1</mn> <mo>*</mo> <mi>u</mi> <mn>1</mn> <mo>+</mo> <mi>u</mi> <mn>2</mn> <mo>*</mo> <mi>u</mi> <mn>2</mn> </mrow> </msqrt> <mo>;</mo> </mrow>

   3) as b1=b2=b3：

   H=b1=b2=b3.