CN202770568U - Rock-soil three-dimensional crushing stress sensor based on optical fiber grating sensing - Google Patents

Abstract

The utility model discloses a rock-soil three-way compressive stress sensor based on optical fiber grating sensing, which comprises a cubic box body with six sides, of which the three sides with common vertices are force-bearing surfaces, and the other common vertices are stress-bearing surfaces. There is a concave disc on each of the three surfaces, which is called the concave disc surface; there are fastening screw holes of the same size and uniform distribution around the concave disc, and there is an optical fiber channel in the center of the concave disc, and the sensing film is connected to the concave disc; The small round thin plate in the middle of the sensing film is the effective pressure bearing surface, and the fiber grating is pasted on its inner surface. The surrounding of the effective pressure bearing surface is the supporting end of the sensing film, and there are screw holes of the same size and evenly distributed around the supporting end; Both the apex and the apex of the concave disc surface have box body through openings, and the optical fiber channel is connected to the two box body through openings. The geotechnical three-way compressive stress sensor is intrinsically safe, free from electromagnetic interference, good long-term stability, large measuring range, high precision, good sealing performance, pressure resistance, corrosion resistance, etc.

Description

A kind of rock three-way compressive stress sensor based on optical fiber grating sensing

Technical field

The present invention relates to Geotechnical Engineering monitoring field, more specifically relate to a kind of rock three-way compressive stress sensor based on optical fiber grating sensing, can be used for the stress test of Rock And Soil, be particularly useful for the test of soft rock and soil stress.

Background technology

The existing compressive stress sensor in civil engineering work monitoring field can only be measured the pressure of a direction mostly, China Patent No. is that three patents of ZL03212896.7, ZL200810246302.1, ZL201120082368.9 disclose several compressive stress sensors, differs from one another.But through comprehensive comparison and analysis, mainly there is following several problem in existing compressive stress sensor: 1) sensing principle of existing compressive stress sensor is based on steel chord type mostly, and such sensor test precision is not high enough, good, the easy not drift of sensor long-time stability, be subject to electromagnetic interference (EMI); Or based on the resistance-strain chip, such sensor accuracy is higher, but is subject to that electromagnetic interference (EMI), range are large not, long-time stability are also good not; 2) existing compressive stress sensor mostly can only record a side and upwards pressure, and can not record simultaneously three sides and upward pressure; 3) existing compressive stress sensor is based on electric signal or electric coherent signal mostly, is not essential safe type, can not use in the inferior rugged surroundings of richness coal mine gassy; 4) existing compressive stress sensor be difficult to accomplish to pressure carry out for a long time, Real-Time Monitoring.

At present, the method that civil engineering work rock mass stress field tests is the most frequently used mainly contains hydraulic fracturing and stress relief method.For hydraulic fracturing, its boring packer need to possess good water sealing property under high hydraulic pressure, thereby the method proposed harsh requirement to the integrality of rock mass, so the hydraulic fracturing stress test for complete hard rock body preferably.And the method can only determine that boring direction is assumed to be a principal direction of stress, is essentially the two-dimensional stress measuring method perpendicular to major principal stress and least principal stress in the boring plane.For stress relief method, for the calculated stress value, at first must determine rock mass physico-mechanical properties parameter (such as elastic modulus E and Poisson ratio μ etc.) and the mutual relationship of survey physical quantity (strain) and stress.To rock mass, particularly for containing the soft rock mass in a large amount of cracks, the stress state that the value of the physical and mechanical parameters such as its elastic modulus E and Poisson ratio μ and rock mass are suffered and rock mass test specimen size and shape are closely related, the elastic modulus E that the rock mass test specimen of different sizes draws by test under the different stress and the numerical value of Poisson ratio μ can differ several times even more than ten times, when just requiring to adopt stress relief method test terrestrial stress, this must obtain above sensor length (＞30cm) complete core, and obtain the elastic modulus of core under the stress state (being the stress state of thick cyclinder outer wall uniform-compression) in simulation stress relieving process.Obviously, these require too harsh, for example, deep, colliery soft rock mass mostly is argillaceous agglutination, stood heavily stressed effect, get and be subjected to current scour and the strong Unloading Effect of stress in the core process, in most cases company commander's degree is that the short core of 10cm also is difficult to obtain, thereby is difficult to obtain accurately Mechanics Parameters of Rock Mass by the uniaxial compression experiment.Therefore, utilize stress relief method to carry out the rock mass stress test in the engineering practice unsatisfactory.And other rock mass terrestrial stress method of testing such as acoustic-emission etc., not only can't be competent at the terrestrial stress test of soft rock, and can't record the initial stress on principle.In soil compressive stress monitoring field, the pressure cell more application, and the weak point of existing pressure cell is above being narrated.

In sum, existing Rock And Soil stress test method and the effect of device in engineering practice are unsatisfactory, need invention new Rock And Soil compressive stress proving installation and method.

Summary of the invention

The objective of the invention is to be to disclose a kind of rock three-way compressive stress sensor based on optical fiber grating sensing, this installs essential safety, is not subjected to electromagnetic interference (EMI), and long-time stability are good, and range is large, and precision is high; Can Real-Time Monitoring any three normal stress components.

A kind of rock three-way compressive stress sensor based on optical fiber grating sensing comprises the cube box body, and it is characterized in that: the cube box body has six faces, and wherein three faces on summit are stress surface altogether, and stress surface is the plane; Three faces on summit respectively have a recessed dish altogether in addition, and an optical-fibre channel is arranged in the center of recessed dish, and the fastening screw that size is identical, be evenly distributed is arranged around recessed dish; Respectively connect a sensing membrane on the recessed dish of three faces, three sensing membrane are circular, and middle roundlet thin plate is effective pressure-bearing surface, and its inside surface is pasted with fiber grating, and sensing membrane is screwed on the box body; On the summit of stress surface and the place, summit of recessed dish place face the first box body impenetrating mouth and the second box body impenetrating mouth are arranged respectively, optical-fibre channel links to each other with the second box body impenetrating mouth mutually with the first box body impenetrating mouth.Effectively the pressure-bearing surface inside surface is pasted with fiber grating, and effectively pressure-bearing surface is the sensing membrane support end all around.Sensing membrane support end outside is the screw that size is identical with fastening screw and be evenly distributed, and sensing membrane links to each other with fastening screw by screw and screw and is fixed on the cube box body, and the outer of sensing membrane is the rounding end.The optical cable of drawing of fiber grating is incorporated into cube box body the first box body impenetrating mouth or the second box body impenetrating mouth from optical-fibre channel.

After being embedded in rock three-way compressive stress sensor in rock mass or the soil, the three-dimensional compressive stress sensor begins to be subject to the three-dimensional extruding.Effective pressure-bearing surface on the sensing membrane is perception stress at first, produces the small deflection elastic bending, and produce corresponding strain.Theoretical according to strain transfer, effectively the maximum strain that produces of pressure-bearing surface center will pass to fiber grating, then fiber grating be elongated, thereby its Prague centre wavelength is drifted about.According to the optical fiber grating sensing theory, can be calculated the size of dependent variable by the centre wavelength drift value.Again according to theory of elasticity, can calculate dependent variable and the effective relation between the pressure that is subject to of pressure-bearing surface.Thereby can record three normal stress by a rock three-way compressive stress sensor.

After two rock three-way compressive stress sensors are combined by ad hoc fashion, can record six normal stress components, according to the theoretical space stress state that can calculate any that waits of stress rotating shaft.

The principle of work of rock three-way compressive stress sensor:

Roundlet in the middle of the sensing membrane is actually the fixing circular sheet of a periphery, and according to theory of elasticity, under uniform lateral load effect, circular sheet will produce the small deflection elastic bending, and the maximum strain of circular sheet center and the pass of lateral load are:

$q=\frac{16{\mathrm{Et}}^3}{3a^3(1-{\mathrm{\μ}}^2)}{\mathrm{\ϵ}}_o---\left(1\right)$

In the formula, q represents the uniform lateral load (MPa) that circular sheet is suffered, can think the normal stress on stress surface of three-dimensional compressive stress sensor; E represents the elastic modulus (MPa) of circular sheet material therefor; T represents the thickness (mm) of circular sheet; μ is the Poisson ratio of circular sheet material therefor; A represents the radius (mm) of circular sheet; ω _oThe maximum strain that represents the circular sheet center to be subjected to horizontal evenly load and produce.

Because the optical fiber with grating is being pasted in the circular sheet center, theoretical according to strain transfer, the maximum strain ε of circular sheet center _oTo all pass to bare optical fibers and bare optical gratings.

Have according to the optical fiber grating sensing theory:

△λ _B＝α _εε _o+α _TΔ _T （2）

In the formula, factor alpha _εThe expression circular sheet passes to grating Prague centre wavelength drift value (pm/ μ ε) that the unit strain of fiber grating causes, is obtained by rating test; Factor alpha _TThe unit strain that the expression temperature variation causes causes the drift value (pm/ μ ε) of grating Prague centre wavelength, is obtained by rating test; Δ λ _BExpression grating Prague centre wavelength drift value (pm); ε _oThe expression circular sheet passes to the strain of fiber grating; Δ _TThe expression temperature variation.

Hollow part is installed a fiber grating that does not stress in the middle of the three-dimensional compressive stress sensor cartridge, and its strain is all caused by temperature variation like this, that is:

Δλ _B′＝α _T′Δ _T （3）

In the formula, factor alpha _TThe unit strain that ' expression temperature variation causes causes the drift value (pm/ μ ε) of grating Prague centre wavelength, Δ λ _B' expression grating Prague centre wavelength drift value (pm), △ _TThe expression temperature variation.Because the pressure cell small volume, so can think that the temperature variation at place, four fiber grating places is consistent, can calculate the strain that circular sheet passes to fiber grating according to formula (2) and formula (3) like this and be:

${\mathrm{\ϵ}}_o=\frac{\mathrm{\Δ}{\mathrm{\λ}}_B-\mathrm{\Δ}{{\mathrm{\λ}}_B}^{\′}{\mathrm{\α}}_T/{\mathrm{\α}}_{T^{\′}}}{{\mathrm{\α}}_{\mathrm{\ϵ}}}---\left(4\right)$

Simultaneous formula (1) and formula (4) have:

$q=\frac{16{\mathrm{Et}}^3}{3a^3(1-{\mathrm{\μ}}^2)}\·\frac{\mathrm{\Δ}{\mathrm{\λ}}_B-\mathrm{\Δ}{{\mathrm{\λ}}_B}^{\′}{\mathrm{\α}}_T/{\mathrm{\α}}_{T^{\′}}}{{\mathrm{\α}}_{\mathrm{\ϵ}}}---\left(5\right)$

Formula (5) is the basic functional principle of sensing membrane.

A three-dimensional compressive stress sensor can record three normal stress components, and two three-dimensional compressive stress sensors can record six normal stress components.Altogether summit and orthogonal three ribs are set up space coordinates oxyz as each change in coordinate axis direction take sensor cartridge; Take the common summit of another sensor cartridge and orthogonal three ribs as each change in coordinate axis direction, set up space coordinates o ' x ' y ' z ' (o and o ' be at a distance of nearer, can be similar to think coincidence).The components of stress that first sensor is surveyed are made as σ _x, σ _y, σ _zThe components of stress that another sensor is surveyed are made as σ ' _x, σ ' _y, σ ' _zAnd establish l ₁, l ₂, l ₃Be respectively x ', y ', the direction cosine between z ' axle and the x axle; m ₁, m ₂, m ₃Be respectively x ', y ', the direction cosine between z ' axle and the y axle; n ₁, n ₂, n ₃Be respectively x ', y ', the direction cosine between z ' axle and the z axle.With six normal stress component substitution following formulas, can draw the stress state (σ at institute measuring point place _x, σ _y, σ _z, τ _Yz, τ _Zx, τ _Xy).

$\left\{\begin{array}{c}{\mathrm{\&sigma;}}_x^{\&prime;}={\mathrm{\&sigma;}}_{\mathrm{<figure-callout\; id="1"\; label="x\; l"\; filenames="DEST\_PATH\_HDA00002242232800011.png,DEST\_PATH\_HDA00002242232800022.png"\; state="\{\{state\}\}">x</figure-callout>}}{l}_{}^{}{}_1^2+{\mathrm{\&sigma;}}_y{\mathrm{<figure-callout\; id="1"\; label="m"\; filenames="DEST\_PATH\_HDA00002242232800011.png,DEST\_PATH\_HDA00002242232800022.png"\; state="\{\{state\}\}">m</figure-callout>}}_1^2+{\mathrm{\&sigma;}}_{\mathrm{<figure-callout\; id="1"\; label="z\; n"\; filenames="DEST\_PATH\_HDA00002242232800011.png,DEST\_PATH\_HDA00002242232800022.png"\; state="\{\{state\}\}">z</figure-callout>}}{n}_{}^{}{}_1^2+2{\mathrm{\&tau;}}_{\mathrm{xy}}{l}_1{\mathrm{<figure-callout\; id="1"\; label="m"\; filenames="DEST\_PATH\_HDA00002242232800011.png,DEST\_PATH\_HDA00002242232800022.png"\; state="\{\{state\}\}">m</figure-callout>}}_1+2{\mathrm{\&tau;}}_{\mathrm{yz}}{m}_1{\mathrm{<figure-callout\; id="1"\; label="n"\; filenames="DEST\_PATH\_HDA00002242232800011.png,DEST\_PATH\_HDA00002242232800022.png"\; state="\{\{state\}\}">n</figure-callout>}}_1+2{\mathrm{\&tau;}}_{\mathrm{zx}}{n}_1{\mathrm{<figure-callout\; id="1"\; label="l"\; filenames="DEST\_PATH\_HDA00002242232800011.png,DEST\_PATH\_HDA00002242232800022.png"\; state="\{\{state\}\}">l</figure-callout>}}_1\\ {\mathrm{\&sigma;}}_y^{\&prime;}={\mathrm{\&sigma;}}_x{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="DEST\_PATH\_HDA00002242232800031.png"\; state="\{\{state\}\}">l</figure-callout>}}_2^2+{\mathrm{\&sigma;}}_y{\mathrm{<figure-callout\; id="2"\; label="m"\; filenames="DEST\_PATH\_HDA00002242232800031.png"\; state="\{\{state\}\}">m</figure-callout>}}_2^2+{\mathrm{\&sigma;}}_{\mathrm{<figure-callout\; id="2"\; label="z\; n"\; filenames="DEST\_PATH\_HDA00002242232800031.png"\; state="\{\{state\}\}">z</figure-callout>}}{n}_{}^{}{}_2^2+2{\mathrm{\&tau;}}_{\mathrm{xy}}{l}_2{\mathrm{<figure-callout\; id="2"\; label="m"\; filenames="DEST\_PATH\_HDA00002242232800031.png"\; state="\{\{state\}\}">m</figure-callout>}}_2+2{\mathrm{\&tau;}}_{\mathrm{yz}}{m}_2{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="DEST\_PATH\_HDA00002242232800031.png"\; state="\{\{state\}\}">n</figure-callout>}}_2+2{\mathrm{\&tau;}}_{\mathrm{zx}}{n}_2{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="DEST\_PATH\_HDA00002242232800031.png"\; state="\{\{state\}\}">l</figure-callout>}}_2\\ {\mathrm{\&sigma;}}_z^{\&prime;}={\mathrm{\&sigma;}}_x{l}_3^2+{\mathrm{\&sigma;}}_y{m}_3^2+{\mathrm{\&sigma;}}_z{n}_3^2+2{\mathrm{\&tau;}}_{\mathrm{xy}}{l}_3{m}_3+2{\mathrm{\&tau;}}_{\mathrm{yz}}{m}_3{n}_3+2{\mathrm{\&tau;}}_{\mathrm{zx}}{n}_3{l}_3\\ {\mathrm{\&tau;}}_{\mathrm{yz}}^{\&prime;}={\mathrm{\&sigma;}}_x{l}_2{l}_3+{\mathrm{\&sigma;}}_y{m}_2{m}_3+{\mathrm{\&sigma;}}_z{n}_2{n}_3\\ +{\mathrm{\&tau;}}_{\mathrm{xy}}(l_2{m}_3+l_3{m}_2)+{\mathrm{\&tau;}}_{\mathrm{yz}}(m_2{n}_3+m_3{n}_2)+{\mathrm{\&tau;}}_{\mathrm{zx}}(n_2{l}_3+n_3{l}_2)\\ {\mathrm{\&tau;}}_{\mathrm{zx}}^{\&prime;}={\mathrm{\&sigma;}}_x{l}_3{\mathrm{<figure-callout\; id="1"\; label="l"\; filenames="DEST\_PATH\_HDA00002242232800011.png,DEST\_PATH\_HDA00002242232800022.png"\; state="\{\{state\}\}">l</figure-callout>}}_1+{\mathrm{\&sigma;}}_y{m}_3{\mathrm{<figure-callout\; id="1"\; label="m"\; filenames="DEST\_PATH\_HDA00002242232800011.png,DEST\_PATH\_HDA00002242232800022.png"\; state="\{\{state\}\}">m</figure-callout>}}_1+{\mathrm{\&sigma;}}_z{n}_3{\mathrm{<figure-callout\; id="1"\; label="n"\; filenames="DEST\_PATH\_HDA00002242232800011.png,DEST\_PATH\_HDA00002242232800022.png"\; state="\{\{state\}\}">n</figure-callout>}}_1\\ +{\mathrm{\&tau;}}_{\mathrm{xy}}(l_3{\mathrm{<figure-callout\; id="1"\; label="m"\; filenames="DEST\_PATH\_HDA00002242232800011.png,DEST\_PATH\_HDA00002242232800022.png"\; state="\{\{state\}\}">m</figure-callout>}}_1+l_1{m}_3)+{\mathrm{\&tau;}}_{\mathrm{yz}}(m_3{\mathrm{<figure-callout\; id="1"\; label="n"\; filenames="DEST\_PATH\_HDA00002242232800011.png,DEST\_PATH\_HDA00002242232800022.png"\; state="\{\{state\}\}">n</figure-callout>}}_1+m_1{n}_3)+{\mathrm{\&tau;}}_{\mathrm{zx}}(n_3{\mathrm{<figure-callout\; id="1"\; label="l"\; filenames="DEST\_PATH\_HDA00002242232800011.png,DEST\_PATH\_HDA00002242232800022.png"\; state="\{\{state\}\}">l</figure-callout>}}_1+n_1{l}_3)\\ {\mathrm{\&tau;}}_{\mathrm{xy}}^{\&prime;}={\mathrm{\&sigma;}}_x{l}_1{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="DEST\_PATH\_HDA00002242232800031.png"\; state="\{\{state\}\}">l</figure-callout>}}_2+{\mathrm{\&sigma;}}_y{m}_1{\mathrm{<figure-callout\; id="2"\; label="m"\; filenames="DEST\_PATH\_HDA00002242232800031.png"\; state="\{\{state\}\}">m</figure-callout>}}_2+{\mathrm{\&sigma;}}_z{n}_1{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="DEST\_PATH\_HDA00002242232800031.png"\; state="\{\{state\}\}">n</figure-callout>}}_2\\ +{\mathrm{\&tau;}}_{\mathrm{xy}}(l_1{\mathrm{<figure-callout\; id="2"\; label="m"\; filenames="DEST\_PATH\_HDA00002242232800031.png"\; state="\{\{state\}\}">m</figure-callout>}}_2+l_2{m}_1)+{\mathrm{\&tau;}}_{\mathrm{yz}}(m_1{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="DEST\_PATH\_HDA00002242232800031.png"\; state="\{\{state\}\}">n</figure-callout>}}_2+m_2{n}_1)+{\mathrm{\&tau;}}_{\mathrm{zx}}(n_1{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="DEST\_PATH\_HDA00002242232800031.png"\; state="\{\{state\}\}">l</figure-callout>}}_2+n_2{l}_1)\end{array}\right.---\left(6\right)$

In the formula, σ _x, σ _y, σ _zBe three measured normal stress components of first sensor in the test cell; τ _Xy, τ _Yz, τ _ZxFor surveying three shear stress that face is subject to of normal stress component with first sensor; σ ' _x, σ ' _y, σ ' _zThree normal stress components for second sensor gained in the test cell; τ ' _Yz, τ ' _Zx, τ ' _XyFor surveying three shear stress that face is subject to of normal stress component with second sensor; l ₁, l ₂, l ₃Be respectively x ', y ', the direction cosine between z ' axle and the x axle; m ₁, m ₂, m ₃Be respectively x ', y ', the direction cosine between z ' axle and the y axle; n ₁, n ₂, n ₃Be respectively x ', y ', the direction cosine between z ' axle and the z axle.

The present invention has the following advantages:

1. this device essential safety is not subjected to electromagnetic interference (EMI), and long-time stability are good, and range is large, and precision is high, and good seal performance is withstand voltage, and is corrosion-resistant.

2. this device is applicable to the pressure test of Rock And Soil, is particularly useful for the pressure test of soft rock and soil, and STRESS VARIATION that can the Real-Time Monitoring Rock And Soil.

3. this device can once record three the normal stress components of a bit, calculates the space stress state of any thereby two sensor combinations can record six normal stress components together.

4. when utilizing this measurement device and resolving in the Rock And Soil space stress state of a bit, do not need Rock And Soil made the hypothesis such as homogeneous, isotropy, do not need the stress direction of Rock And Soil and parameter etc. are made various hypothesis yet, overcome the drawback of existing Rock And Soil stress test.

Description of drawings

Fig. 1 is a kind of front view of the rock three-way compressive stress sensor based on optical fiber grating sensing.

Fig. 2 is a kind of oblique two side figure of the rock three-way compressive stress sensor based on optical fiber grating sensing.

Fig. 3 is a kind of vertical view of sensitive face of the rock three-way compressive stress sensor based on optical fiber grating sensing.

Fig. 4 is a kind of vertical view of the rock three-way compressive stress sensor cartridge sensitive face (sensitive face when not installing sensing membrane) based on optical fiber grating sensing.

Fig. 5 is a kind of side view of sensing membrane.

Fig. 6 is a kind of vertical view of sensing membrane.

Fig. 7 is a kind of vertical view of the rock three-way compressive stress sensor stress surface (being the box body stress surface) based on optical fiber grating sensing.

Wherein:

1-box body, 1-1-rounding summit, 1-2-box body impenetrating mouth, 1-3-fastening screw, 1-4-recessed dish (face), 1-5-optical-fibre channel;

The 2-sensing membrane, 2-1-screw, 2-2-fiber grating, 2-3-sensing membrane support end, 2-4-rounding end, the effective pressure-bearing surface of 2-5-, 2-6-screw;

The 3-stress surface, 3-1-rounding summit, 3-2-box body impenetrating mouth.

Embodiment

Describe in detail below in conjunction with drawings and Examples:

A kind of rock three-way compressive stress sensor based on optical fiber grating sensing comprises cube box body 1, and cube box body 1 has six faces, and wherein three faces on summit are stress surface 3 altogether, and stress surface 3 is the plane; Three faces on summit respectively have a recessed dish 1-4 altogether in addition, in the center of recessed dish 1-4 an optical-fibre channel 1-5 are arranged, and the fastening screw 1-3 that size is identical, be evenly distributed is arranged around recessed dish; On the recessed dish 1-4 of three faces relative with stress surface, respectively be connected with a sensing membrane 2, three sensing membrane 2 are circular configuration, middle roundlet thin plate is effective pressure-bearing surface 2-5, and its inside surface is pasted with fiber grating 2-2, and sensing membrane 2 is fixed on the cube box body 1 by screw 2-6.

Its concrete annexation is: cube box body 1 has six faces, and wherein altogether three stress surfaces 3 on summit link to each other mutually, and three faces on the common summit relative with three stress surfaces link to each other mutually in addition.Stress surface 3 is the plane, at its place, total summit the second box body impenetrating mouth 3-2 is arranged, and is used for drawing optical cable etc.Three faces relative with three stress surfaces, 3 difference are the summit altogether, and there is the first box body impenetrating mouth 1-2 at the place on the summit; A recessed dish 1-4 is respectively arranged on three faces, in the center of recessed dish 1-4 an optical-fibre channel 1-5 is arranged, the fastening screw 1-3 that size is identical, be evenly distributed is arranged around recessed dish.Optical-fibre channel 1-5, box body impenetrating mouth 1-2 are mutually to link to each other with 3-2, are mainly used in drawing optical cable etc.Roundlet in the middle of the sensing membrane 2 is effective pressure-bearing surface 2-5; Effectively pressure-bearing surface 2-5 inside surface is pasted with fiber grating 2-2, is used for stress sensing; Effectively pressure-bearing surface 2-5's is sensing membrane support end 2-3 all around, is used for inserting and is close to recessed dish 1-4 inwall to reach the better fixedly effect of sensing membrane 2; Sensing membrane support end 2-3 outside is the screw 2-1 that size is identical with fastening screw 1-3 and be evenly distributed, and is used for sensing membrane 2 is fixed on box body 1; The outer of sensing membrane 2 is rounding end 2-4, reduces as far as possible the sensing membrane 2 concentrated disturbing factor that waits of the most advanced and sophisticated stress that causes all around with this.Screw 2-1 on the sensing membrane 2 is alignd one by one with recessed dish fastening screw 1-3 all around, then screw 2-6 is screwed among screw 2-1 and the 1-3, with this sensing membrane 2 is fastened on the box body 1.The optical cable of drawing of fiber grating 2-2 is incorporated into the first box body impenetrating mouth 1-2 or the second box body impenetrating mouth 3-2 from optical-fibre channel 1-5, and then draws outside the box body 1 from the first box body impenetrating mouth 1-2 or the second box body impenetrating mouth 3-2.

After being embedded in rock three-way compressive stress sensor in rock mass or the soil, sensor begins to be subject to the three-dimensional extruding.Effective pressure-bearing surface 2-5 on the sensing membrane 2 is perception stress at first, produces the small deflection elastic bending, and produce corresponding strain.Theoretical according to strain transfer, effectively the maximum strain that produces of pressure-bearing surface 2-5 center will pass to fiber grating 2-2, then fiber grating 2-2 be elongated, thereby its Prague centre wavelength is drifted about.According to the optical fiber grating sensing theory, can be calculated the size of dependent variable by the centre wavelength drift value.Again according to theory of elasticity, can calculate dependent variable and the effective relation between the pressure that is subject to of pressure-bearing surface 2-5.Thereby can record three normal stress by a rock three-way compressive stress sensor.

After two rock three-way compressive stress sensors are combined by ad hoc fashion, can record six normal stress components, according to the theoretical space stress state that can calculate any that waits of stress rotating shaft.

Claims (4)

1. the rock three-way compressive stress sensor based on optical fiber grating sensing comprises cube box body (1), and it is characterized in that: cube box body (1) has six faces, and wherein three faces on summit are stress surface (3) altogether, and stress surface (3) is the plane; Three faces on summit respectively have a recessed dish (1-4) altogether in addition, in the center of recessed dish (1-4) optical-fibre channel (1-5) are arranged, and the fastening screw (1-3) that size is identical, be evenly distributed is arranged around recessed dish; On the recessed dish (1-4) of three faces, respectively connect a sensing membrane (2), three sensing membrane (2) are circular, middle roundlet thin plate is effective pressure-bearing surface (2-5), and its inside surface is pasted with fiber grating (2-2), and sensing membrane (2) is fixed on the box body (1) by screw (2-6); On the summit of stress surface (3) and the place, summit of recessed dish (1-4) place face the first box body impenetrating mouth (1-2) and the second box body impenetrating mouth (3-2) are arranged respectively, optical-fibre channel (1-5) links to each other with the second box body impenetrating mouth (3-2) mutually with the first box body impenetrating mouth (1-2).

2. a kind of rock three-way compressive stress sensor based on optical fiber grating sensing according to claim 1, it is characterized in that: described effective pressure-bearing surface (2-5) inside surface is pasted with fiber grating (2-2), and effectively pressure-bearing surface (2-5) is sensing membrane support end (2-3) all around.

3. a kind of rock three-way compressive stress sensor based on optical fiber grating sensing according to claim 1, it is characterized in that: described sensing membrane support end (2-3) outside is the screw (2-1) that size is identical with fastening screw (1-3) and be evenly distributed, sensing membrane (2) links to each other with fastening screw (1-3) with screw (2-1) by screw (2-6) and is fixed on the box body (1), and the outer of sensing membrane (2) is rounding end (2-4).

4. a kind of rock three-way compressive stress sensor based on optical fiber grating sensing according to claim 1, it is characterized in that: the optical cable of drawing of described fiber grating (2-2) is incorporated into cube box body the first box body impenetrating mouth (1-2) or the second box body impenetrating mouth (3-2) from optical-fibre channel (1-5).

Images