CN203396682U - Plugging test device of pervious concrete pile under earthquake action - Google Patents

Abstract

The utility model relates to a plugging test device of a pervious concrete pile under earthquake action. The whole plugging process of the pervious concrete pile is simulated by testing a permeability coefficient of a pervious concrete sample in liquefiable soil and a change of electrical resistivity of a saturated sample under earthquake action, and a foundation is established for the plugging mechanism of the pervious concrete pile in the liquefiable soil under earthquake action. The plugging test device comprises a vibrating table for simulating the earthquake action; a sleeve is placed on the vibrating table; a liquefiable soil sample is filled into the sleeve; a pervious concrete sample is filled at the lower part of the liquefiable soil sample; preformed holes of pressure meters are respectively arranged on the sleeve walls at the upper and lower sides of the pervious concrete sample; the pressure meters are arranged for measuring a pressure difference of the upper and lower sides of the pervious concrete sample; meanwhile, resistivity detectors are also arranged at the upper end and the lower end of the pervious concrete sample; a drain pipe for controlling drainage is arranged at the lower part of the sleeve; a flow detector is arranged on the drain pipe; a water inlet and an overfall gap are also formed at the upper part of the sleeve.

Description

Permeable concrete stake clogging testing device under geological process

Technical field:

The utility model relates to permeable concrete stake clogging testing device under a kind of geological process, belongs to field of civil engineering.

Background technology:

The loose powder, fine sand soil that sand liquefaction refers to full water Sudden failure and present liquid phenomenon under effect of vibration.If dispose liquefying soil ground with permeable concrete stake, when geological process occurs, sand grains can enter in permeable concrete stake and then stop up permeable concrete stake, affects its usability.Therefore study the blocking mechanism of permeable concrete stake under geological process in liquefying soil and be necessary, but lack at present under geological process permeable concrete stake blocking test analogue means and method in liquefying soil.

Utility model content:

The purpose of this utility model is exactly for addressing the above problem, permeable concrete stake clogging testing device under a kind of geological process is provided, by under test geological process in liquefying soil the variation of permeable concrete test specimen infiltration coefficient and full water test specimen resistivity permeable concrete stake stopped up to overall process simulate, for the blocking mechanism of permeable concrete stake in liquefying soil under Study of Seismic effect lays the foundation.

To achieve these goals, the utility model adopts following technical scheme:

Under a permeable concrete stake clogging testing device, it comprises the shaking table of a failure under earthquake action, places sleeve on shaking table, loads liquefying soil test specimen in sleeve, permeable concrete test specimen is loaded in liquefying soil test specimen bottom; Sleeve wall in permeable concrete test specimen upper and lower sides position is respectively equipped with tensimeter preformed hole, and on it, setting pressure table is used for measuring permeable concrete test specimen upper and lower sides pressure differential; At permeable concrete test specimen upper and lower side, be also provided with resistivity detecting device simultaneously; In lower cartridge, be provided with for controlling the drainpipe of draining, drainpipe is provided with flow detector, and upper cartridge is also provided with water inlet and gap.

Described resistivity detecting device comprises the entanglement that is arranged on permeable concrete test specimen top and bottom, and two entanglement are connected with power supply with multimeter.

Described permeable concrete test specimen outer wrap rubber sleeve, rubber sleeve is as in inner sleeve, and inner sleeve is placed in sleeve.

Described drainage pipe end is provided with height-adjustable plastic tube, for measuring the stopping state of cocoa liquefying soil to permeable concrete under different drain heights.

Described shaking table adopts the electromagnetic wave exciting that Signal Generator of Ultra-low Frequency is sent to drive table top, and generator adopts input square wave, triangular wave, sine wave or real seismic event; It is 1-100Hz that frequency is inputted out in vibration, and it is 8-20mm that table top allows maximum displacement, and level is 0.5g-2g to maximum exciting acceleration.

Described permeable concrete height of specimen is the wall thickness of the permeable concrete stake that simulated, and permeable concrete stake adopts the stake of open circles wall.

Described liquefying soil height h _sfor:

$h_s=\frac{d_e-\mathrm{<figure-callout\; id="2"\; label="d"\; filenames="HDA0000375149150000011.png"\; state="\{\{state\}\}">d</figure-callout>}}{2}$

In formula: the permeable concrete Zhuan Zhuan footpath of d-simulated, d _e-single pile Equivalence effects circular diameter;

Wherein, in liquefying soil is inserted in the stake of simulation permeable concrete and while pressing arranged in squares, d _e=1.13s, s is pile spacing;

In liquefying soil is inserted in the stake of simulation permeable concrete and while pressing triangular arrangement, d _e=1.05s, s is pile spacing.

Detailed process is:

(1) make permeable concrete stake test specimen and liquefying soil test specimen;

(2) by volumetric method, measure the porosity of permeable concrete test specimen;

(3) measure the infiltration coefficient of permeable concrete test specimen;

(4) liquefying soil blocking test

4-1) after osmotic coefficient investigating, keep flow of inlet water constant, the liquefying soil test specimen sidewall of making is superscribed after flexible rubber electricity layer, in embedding device, static a period of time;

4-2) open shaking table, the ripple that input is set, starts vibrations process;

4-3) observe the flow Q of the discharge water pipe of online record ₁, utilize Darcy's law, ask the osmotic coefficient k of pervious concrete test specimen in seismic process ₁;

(5) Experiment of Resistivity Variation in test specimen obstruction process

When test (4) starts, calculate corresponding resistivity λ;

Only change some in test parameters below, the impact of research relevant parameter on the anti-blockage capability of pervious concrete test specimen.These parameters comprise: permeable concrete test specimen porosity, the grating of liquefying soil, the waveform of seismic event;

By above-mentioned experiment, obtain permeable concrete test specimen and stopped up in overall process the variation of infiltration coefficient, these 2 indexs of the variation of resistivity, by analyzing the variation of these 2 indexs, make clear of the laws for plugging of water-based concrete road surface by liquefying soil.

Described step (2) mesoporosity rate mensuration process is:

The diameter and the height that with vernier caliper, measure test specimen, calculate porosity according to formula (1):

$n_e=(1-\frac{m_2-{\mathrm{<figure-callout\; id="1"\; label="m"\; filenames="HDA0000375149150000011.png"\; state="\{\{state\}\}">m</figure-callout>}}_1}{{\mathrm{v\&rho;}}_w})\&times;100---\left(1\right)$

In formula: n _e---test specimen porosity, %;

M ₁---the quality that test specimen immersion recorded after 24 hours in water, g;

M ₂---after test specimen takes out from water 60 ℃ of baking ovens in dry the quality after 24 hours, g;

The test specimen volume that v---volumetric method is measured, cm ³;

ρ _w---the density of water, g/cm ³;

In described step (3), osmotic coefficient investigating process is:

3-1) according to permeable concrete test specimen diameter, calculate permeable concrete test specimen cross-sectional area A;

3-2) permeable concrete test specimen is put into NaCl solution and soak certain hour, guarantee that the hole of all connections can soak into;

3-3) permeable concrete test specimen is taken out, dry surperficial Bing side coating butter, then apply with flexible rubber bed course, be arranged in sleeve;

3-4) in sleeve, start slow water filling, current are filled whole test specimen sleeve from top to bottom, and sleeve beginning overflow suitable for reading; Open outlet valve, make water seepage flow a period of time, after waterflow stabilization and bubble emptying, start test;

The seepage flow that 3-5) reads online record is discharged the flow on water pipe, gets the Q value of curve when steady; According to the difference of the pressure on the upper and lower surface of test specimen of online record, determine hydraulic gradient J,

$J=\frac{h_w}{l}=\frac{h_1-h_2}{l}$

In formula: h ₁and h ₂-permeable concrete test specimen upper and lower surface pressure;

H _w-the loss of flood peak of flowing through after test specimen;

L-height of specimen;

3-6) utilize Darcy's law to ask osmotic coefficient k

$k=\frac{Q}{\mathrm{AJ}}$

In formula: A-permeable concrete test specimen cross-sectional area.

Described determination of resistivity process is: press U to permeable concrete test specimen upper and lower surface indirect current, and measure by the electric current I of test specimen upper and lower surface by the multimeter of online record, utilize R=U/I, obtain test specimen resistance R, utilize resistivity to calculate the resistivity λ that formula (5) is tried to achieve test specimen

λ=RA/I （5）。

The utility model device is divided into three parts, sleeve part, drainpipe and shaking table.Sleeve part is used for laying permeable concrete test specimen, liquefying soil soil test specimen.In upper and lower both sides, permeable concrete test specimen position, be drilled with tensimeter preformed hole, for connecting plus-pressure table, measure the upper and lower pressure at both sides of test specimen poor.Drainpipe is used for controlling draining, electromagnetic flowmeter is installed on drainpipe and is carried out measuring flow.Drainage pipe end adds height-adjustable plastic tube, for measuring the stopping state of cocoa liquefying soil to permeable concrete under different drain heights.Shaking table is for failure under earthquake action.

Its principle of work is as follows:

Liquefying soil has the trend that becomes more closely knit under geological process, and pore water pressure rises, and former cause soil particle indirect contact point transmission of pressure is reduced.After pressure completely loses, the soil body becomes as the liquid.If dispose liquefying soil ground with permeable concrete stake, when geological process occurs, sand grains can enter in permeable concrete stake and then stop up permeable concrete stake, affects its usability.In order to simulate whole obstruction process, utility model experimental provision as shown in Figure 1.During test, in sleeve, upside is placed liquefying soil test specimen, and downside is placed permeable concrete test specimen.When geological process occurs, sand grains can be jammed in the permeable concrete test specimen being placed on below liquefying soil test specimen under the drive of wandering water, by the infiltration coefficient of observation permeable concrete test specimen and the variation of resistivity, can determine the stopping state of permeable concrete test specimen.

The beneficial effects of the utility model are: the blocking mechanism that the utility model is permeable concrete stake in liquefying soil under Study of Seismic effect provides a kind of research method and relevant device of science.Realized the simulation that under geological process, in liquefying soil, overall process is stopped up in permeable concrete stake, by measuring the stopping state of liquefying soil to permeable concrete under different drain heights and vibration acceleration, can obtain the variation that permeable concrete stops up infiltration coefficient and resistivity in overall process.Experimental facilities is simple in structure, and measurement result accurate and effective is laid a good foundation for making clear of the blocking mechanism of water-based concrete-pile.

Accompanying drawing explanation:

Fig. 1 is structural representation of the present utility model;

The schematic diagram that Fig. 2 lays out pile for square;

Fig. 2 a is single pile Equivalence effects area schematic diagram;

Fig. 3 is the schematic diagram that triangle lays out pile;

Fig. 3 a is single pile Equivalence effects area schematic diagram;

Fig. 4 is sand sample grading curve;

Fig. 5 is A, two groups of test specimen change in resistance figure of B.

Wherein, 1. sleeve, 2. tensimeter preformed hole I, 3. inner sleeve, 4. power supply and multimeter, 5. tensimeter preformed hole II, 6. shaking table, 7. entanglement, 8. joint flange, 9. pervious concrete test specimen, 10. rubber sleeve, 11. liquefying soil test specimens, 12. gaps, 13. drainpipes, 14. valves, 15. electromagnetic flowmeters, 16. plastic tubes, 17. permeable concrete stakes, 18. liquefying soils.

Embodiment:

Below in conjunction with accompanying drawing and embodiment, the utility model is described further.

In Fig. 1, the utility model device comprises a sleeve 1, and it is divided into two parts and is formed by connecting by joint flange 8.In sleeve 1, be also provided with an inner sleeve 3(and can adopt organic glass or other transparent material), in inner sleeve 3, be filled with the outside permeable concrete test specimen 9 being wrapped up by rubber sleeve 10, upper sleeve 1 at permeable concrete test specimen 9 is filled liquefying soil test specimen 11, and sleeve 1 top is provided with water inlet (not drawing in figure) and gap 12.

The upper and lower side of permeable concrete test specimen 9 is entanglement 7, and entanglement 7 is connected with multimeter 4 with power supply; In the upper and lower of permeable concrete test specimen 9, be also provided with tensimeter, tensimeter is arranged on sleeve 1 by tensimeter preformed hole I2 and the tensimeter preformed hole II5 of sleeve 1 simultaneously.

Sleeve 1 bottom is connected with drainpipe 13, drainpipe 13 is provided with valve 14, on drainpipe 13, be also connected with electromagnetic flowmeter 15, drainpipe is connected with height-adjustable plastics 16, for measuring the stopping state of cocoa liquefying soil to permeable concrete under different drain heights.

Whole sleeve 1 is placed on shaking table 6, and shaking table is for failure under earthquake action.Experiment adopts the electromagnetic wave exciting that Signal Generator of Ultra-low Frequency is sent to drive table top, and generator can be inputted the waveforms such as square wave, triangular wave, sine wave, also can input real seismic event.It is 1-100Hz that frequency is inputted out in vibration, and it is 8-20mm that table top allows maximum displacement, and level is 0.5g-2g to maximum exciting acceleration.

Experiment process is:

(1) make permeable concrete test specimen 9 and liquefying soil test specimen 11.

Permeable concrete stake 17 adopts the stake of open circles wall, and the height of permeable concrete test specimen 9 is the wall thickness of permeable concrete stake.

Permeable concrete stake 17 is inserted in liquefying soil 18, if arranged in squares is pressed in permeable concrete stake 17, it is arranged as shown in Fig. 2, Fig. 2 a.According to standard, pile spacing should be got 3-5 Bei Zhuan footpath d.The equivalent diameter of the ground processing area that permeable concrete stake 17 is shared calculates by formula (6).

d _e＝1.13s (6)

In formula: d _e-single pile Equivalence effects circular diameter;

S-pile spacing.

From above formula, during experiment, the height h of liquefying soil 18 _sby formula (7), determine.

$h_s=\frac{d_e-d}{2}---\left(7\right)$

In formula: d —Zhuan footpath.

If permeable concrete stake 17 is by triangular arrangement, it is arranged as shown in Fig. 3, Fig. 3 a.The equivalent diameter of the ground processing area that permeable concrete stake 17 is shared calculates by formula (8).

d _e＝1.05s (8)

In formula: d _e-single pile Equivalence effects circular diameter;

S-pile spacing.

From above formula, during experiment, the height h of liquefying soil _sby formula (9), determine.

$h_s=\frac{d_e-d}{2}---\left(9\right)$

In formula: d —Zhuan footpath.

(2) measure the porosity of permeable concrete test specimen 9: permeable concrete test specimen 9 two ends are cut respectively to a part, to eliminate the impact of inhomogeneous generation of vibrating of permeable concrete test specimen 9 upper and lower surfaces, and record permeable concrete test specimen 9 height after cutting.Employing amount volumetric method is measured permeable concrete test specimen 9 porositys, measures diameter and the height of permeable concrete test specimen 9 with vernier caliper, according to formula (1), calculates porosity:

$n_e=(1-\frac{m_2-{\mathrm{<figure-callout\; id="1"\; label="m"\; filenames="HDA0000375149150000011.png"\; state="\{\{state\}\}">m</figure-callout>}}_1}{{\mathrm{v\&rho;}}_w})\&times;100---\left(1\right)$

In formula: n _e---permeable concrete test specimen porosity, %;

M ₁---the quality that the immersion of permeable concrete test specimen recorded after 24 hours in water, g;

M ₂---after permeable concrete test specimen takes out from water 60 ℃ of baking ovens in dry the quality after 24 hours, g;

The permeable concrete test specimen volume that v---volumetric method is measured, cm ³;

ρ _w---the density of water, g/cm ³.

(3) measure the infiltration coefficient of permeable concrete test specimen 9:

3-1) according to permeable concrete test specimen 9 diameters, calculate permeable concrete test specimen 9 cross-sectional area A.

3-2) permeable concrete test specimen 9 is put into NaCl solution and soak certain hour, guarantee that the hole of all connections can soak into.

3-3) permeable concrete test specimen 9 is taken out, dry surperficial Bing side coating butter, then apply with flexible rubber bed course, be arranged on inner sleeve 3 places of organic glass.Two sections sleeve 1 use joint flange 8 is connected, and joint flange 8 places add rubber blanket.

3-4), to the interior slow water filling of sleeve 1, current are filled whole test specimen sleeve 1 from top to bottom, and sleeve 1 gap 12 starts overflow; The valve 14 of opening drainpipe 13, makes water seepage flow a period of time, starts test after waterflow stabilization and bubble emptying.

While 3-5) occurring due to geological process, seepage effect is less on the liquefaction process impact of liquefying soil, so the gap designing on experimental provision and freeing port height differ less, and head difference is less.The seepage flow that reads online record goes out the flow of the electromagnetic flowmeter 15 on drainpipe 13, gets the Q value of curve when steady.According to the difference of the pressure on the permeable concrete test specimen 9 upper and lower surfaces of online record, determine hydraulic gradient J.

$J=\frac{h_w}{l}=\frac{h_1-h_2}{l}---\left(2\right)$

In formula: h ₁and h ₂-permeable concrete test specimen 9 upper and lower surface pressure;

H _w-the loss of flood peak of flowing through after permeable concrete test specimen 9;

9 height of l-permeable concrete test specimen.

3-6) utilize Darcy's law to ask osmotic coefficient k.

$k=\frac{Q}{\mathrm{AJ}}---\left(3\right)$

In formula: A-test specimen cross-sectional area.

(4) liquefying soil blocking test

4-1) after osmotic coefficient investigating, keep flow of inlet water constant, by the liquefying soil test specimen of making, in embedding device, static a period of time.

4-2) open shaking table 6, input seismic event, starts vibrations process.

4-2) observe the flow Q of the drainpipe 13 of online record ₁, utilize Darcy's law, ask the osmotic coefficient k of pervious concrete test specimen 9 in seismic process ₁.

(5) Experiment of Resistivity Variation in test specimen obstruction process

By observing full water permeable concrete test specimen 9 connect the change in resistance process in space, can judge the stopping state of permeable concrete test specimen 9, the perforation space that resistivity is higher shows test specimen less so that the soil particle that is jammed in permeable concrete test specimen 9 of explanation more.In order to record change in resistance process, during experiment, add conductive NaCl solution, and Shang Xia 9, two ends respectively add an entanglement 7 at permeable concrete test specimen, connect power supply and multimeter 4 measurement useful power and applied power, in experimentation, when test (4) starts, give permeable concrete test specimen both sides indirect current pressure U 9 Shang Xia,, utilize this multimeter can record by the electric current I of permeable concrete test specimen 9.Finally utilize formula (4) can try to achieve permeable concrete test specimen 9 resistance R.

R=U/I （4）

After trying to achieve resistance R, can utilize resistivity to calculate the resistivity λ that formula (5) is tried to achieve permeable concrete test specimen 9.

λ=RA/l （5）

In experimentation, because sand constantly stops up permeable concrete test specimen 9, in obstruction process, the porosity of permeable concrete test specimen 9 reduces gradually, causes the resistivity recording constantly to increase.

Only change some in test parameters below, the impact of research relevant parameter on the anti-blockage capability of pervious concrete test specimen 9.These parameters comprise: permeable concrete test specimen porosity, the grating of liquefying soil, the waveform of seismic event etc.

By above-mentioned experiment, can obtain permeable concrete test specimen 9 and by liquefying soil, be stopped up the variation of infiltration coefficient in overall process, 2 indexs of variation of resistivity.By analyzing the variation of these 2 indexs, can make clear of the laws for plugging of water-based concrete road surface.

Example

The liquefiable soil sample of this test has selected two kinds of sand samples to combine: fine sand and flour sand, and its parameter is in Table 1, and grading curve is shown in Fig. 4.

Table 1 sand sample parameter list

During test, make A, two groups of test specimens of B, the ratio of the consumption of A group test specimen fine sand and flour sand is 2:1.The amount ratio of B group test specimen fine sand and flour sand is classified 1:2 as.Two groups of test specimens are identical in quality, and load weighted sand sample is mixed to rear making test specimen.

Permeable concrete test specimen 9 adopts Jinan to produce 42.5 Portland cement of scenery with hills and waters boards, poly-amino high efficiency water reducing agent, and the particle diameter of usining is made as mixing water by general clean tap water as coarse aggregate as the rubble of 10-20mm, 5-10mm, 2.5-5mm etc.Employing experience-volumetric method is determined the match ratio of material, and rule of thumb water cement ratio gets 0.3, and goal porosity 20%, by testing the optimum mix of determining that intensity and water permeability all can meet the demands.Produce condition the same, one group of test specimen that void ratio is identical, height of specimen is 100mm, diameter is 100mm.During experiment, permeable concrete test specimen 9 two ends are cut respectively to 5mm, to eliminate the vibrate impact of inhomogeneous generation of test specimen upper and lower surface, so the final height of permeable concrete test specimen 9 is 90mm.

Getting pilespacing is 4 Bei Zhuan footpaths, during experiment, by square, lays out pile, and the diameter of liquefying soil test specimen 11 is 100mm, is highly 1.76 times of permeable concrete test specimen 9, is 158.4mm.

Complete the variation of the resistivity of two groups of permeable concrete test specimens 9 of the rear observation of experiment, its result as shown in Figure 5.

As shown in Figure 5, the resistivity of A, two groups of permeable concrete test specimens 9 of B is all along with the growth of time is risen gradually, explanation is in experimentation, constantly have sand grains be jammed in permeable concrete test specimen 9 in, the resistivity of A group test specimen is greater than B group, and reason is that A group permeable concrete test specimen 9 large particle diameter sand content are more, is easily jammed in permeable concrete test specimen 9, and B group test specimen small particle diameter content is more, can be deposited in bottom of device by permeable concrete test specimen 9.

Claims (7)

1. permeable concrete stake clogging testing device under a geological process, it is characterized in that, it comprises the shaking table of a failure under earthquake action, places sleeve on shaking table, in sleeve, load liquefying soil test specimen, permeable concrete test specimen is loaded in liquefying soil test specimen bottom; Sleeve wall in permeable concrete test specimen upper and lower sides position is respectively equipped with tensimeter preformed hole, and on it, setting pressure table is used for measuring permeable concrete test specimen upper and lower sides pressure differential; At permeable concrete test specimen upper and lower side, be also provided with resistivity detecting device simultaneously; In lower cartridge, be provided with for controlling the drainpipe of draining, drainpipe is provided with flow detector, and upper cartridge is also provided with water inlet and gap.

2. permeable concrete stake clogging testing device under geological process as claimed in claim 1, is characterized in that, described resistivity detecting device comprises the entanglement that is arranged on permeable concrete test specimen top and bottom, and two entanglement are connected with power supply with multimeter.

3. permeable concrete stake clogging testing device under geological process as claimed in claim 1, is characterized in that, described permeable concrete test specimen outer wrap rubber sleeve, and rubber sleeve is as in inner sleeve, and inner sleeve is placed in sleeve.

4. permeable concrete stake clogging testing device under geological process as claimed in claim 1, it is characterized in that, described drainage pipe end is provided with height-adjustable plastic tube, for measuring the stopping state of cocoa liquefying soil to permeable concrete under different drain heights.

5. permeable concrete stake clogging testing device under geological process as claimed in claim 1, it is characterized in that, described shaking table adopts the electromagnetic wave exciting that Signal Generator of Ultra-low Frequency is sent to drive table top, and generator adopts input square wave, triangular wave, sine wave or real seismic event; It is 1-100Hz that frequency is inputted out in vibration, and it is 8-20mm that table top allows maximum displacement, and level is 0.5g-2g to maximum exciting acceleration.

6. permeable concrete stake clogging testing device under geological process as claimed in claim 1, is characterized in that, described permeable concrete height of specimen is the wall thickness of the permeable concrete stake that simulated, and permeable concrete stake adopts the stake of open circles wall.

7. permeable concrete stake clogging testing device under geological process as claimed in claim 1, is characterized in that, described liquefying soil height h _sfor:

$h_s=\frac{d_e-d}{2}$

In formula: the permeable concrete Zhuan Zhuan footpath of d-simulated, d _e-single pile Equivalence effects circular diameter;

Wherein, in liquefying soil is inserted in the stake of simulation permeable concrete and while pressing arranged in squares, d _e=1.13s, s is pile spacing;

In liquefying soil is inserted in the stake of simulation permeable concrete and while pressing triangular arrangement, d _e=1.05s, s is pile spacing.

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