It is large-scale simple with the vertical seepage deformation tester of coarse-grained soil and test methodTechnical field
The invention belongs to Construction for Hydroelectric Project device and method technical fields, and in particular to match to a kind of large size is simpleThe vertical seepage deformation tester of coarse-grained soil and test method.
Background technique
Building earth and rockfill dam mainly plays water blocking in hydraulic and hydroelectric engineering, in earth and rockfill dam design, first has to combineThe actual requirement of engineering carries out dam body Analysis of The Seepage, can substantially reduce earth and rockfill dam and seepage failure phenomenon occur.Exist to study waterPercolation law and characteristic in dam embankment material soil structures, need to carry out the seepage deformation test of coarse-grained soil, mention for designParameter required for being calculated for dam body Stability analysis on seepage and the reasonable antiseepage type of arrangement of selection.Dam embankment material is common to be hadExplosion rock ballast material, sand gravel material etc., these materials have grain diameter size is big, particle size range is wide, density is big, voidage is big andThe features such as irregular, Penetration Signature rule are different from general homogeneous soil granular materials.The infiltration coefficient concentrated expression soil bodyPenetration Signature, infiltration gradient reflect soil body overall structure impermeability, the two technical indicators need to be measured by laboratory test,Permeability apparatus sample cylinder diameter used in indoor measurement coarse-grained soil permeability test is determined according to sample maximum particle diameter at present, testing regulationsRegulation instrument internal diameter should be greater than sample partial size d855 times, when the instrument internal diameter of routine test cannot be met the requirements, design processingThe seepage deformation instrument of major diameter, or according to sample situation, particle more than maximum allowable partial size can be taken equivalent scalping method, etc.It measures method of substitution, method of similar grading or mixing method and reduced scale processing is carried out to sample, at present laboratory test instrument dimensions masterIf designing for coarse-grained soil (particle less than 60mm), material (usual Dmax≤800mm) infiltration examination is filled to the main enrockment of damThe discussion of proved recipe method is indefinite, takes reduced scale method to seepage deformation test applicability still up for test oversize sized particlesVerifying, scalping method and mixing method will change fine particle content significantly in permeability test reduced scale, and fine fraction is precisely to influence to seepSaturating coefficient determination result key factor, therefore both processing method significant discomforts are preferably used for permeability test；Method of similar grading is mostPipe keeps gradation nonuniformity coefficient constant, but in this way the gradation particle composition after reduced scale and former grading curve difference compared withGreatly, particle obviously attenuates, and fine fraction content matches content much larger than simple, is obviously reduced with its measured infiltration coefficient, differsAn order of magnitude, therefore this method is also unreasonable；Equivalent substitution method, although taking equivalent substitution fine fraction content measure guarantorCard sample fine particle content is constant, but the equivalent replacement of fine fraction varying particle size will influence whether the change of rest part contentChange, measurement infiltration coefficient result will certainly also be had an impact in this way, therefore this method is reasonable instead of grain in the presence of how to determineDiameter and it is maximum allow replace amount technical problem.In conclusion scale effect is to coarse-grained soil or even coarse-grained soil permeability test knotFruit Accurate Determining adversely affects, and therefore, coarse grain class soil permeability test should match Specimen Determination using simple, but present triesIt tests in regulation and does not suggest that coarse-grained soil permeability test specific method, also the vertical seepage deformation instrument of unformed coarse-grained soil.
Summary of the invention
Technical problem to be solved by the present invention lies in above-mentioned the deficiencies in the prior art are overcome, provide it is a kind of design rationally,The large size that structure is simple, the functions such as automatic pressure supply, constant pressure, pressurization can be achieved, substantially increase experimental accuracy is simple with thickThe vertical seepage deformation tester of grain soil and test method.
Solve above-mentioned technical problem the technical solution adopted is that: be provided with pedestal on bracket, be provided with transition on pedestalCylinder, transitional cylinder top are provided with the first porous disc, test cylinder are provided on the first porous disc, and survey pressure is provided on test cylinder side wallUnit and exhaust pipe are provided with exhaust valve on exhaust pipe, and pressure measuring unit is connected with test cylinder, are provided with and catchment at the top of test cylinderCylinder, Water collecting tube top are provided with top plate, the drainpipe of installation drain valve are provided on Water collecting tube side wall, and drainpipe is connected with graduated cylinderLogical, pedestal lower part is connected with water inlet pipe one end, and inlet valve is equipped on water inlet pipe, and the water inlet pipe other end is connected with pressurized tankLogical, pressurized tank is connected with variable frequency adjustment pump group, is provided with ductwork pressure on the pipeline between pressurized tank and variable frequency adjustment pump groupSensor, variable frequency adjustment pump group are connected with water tank, and ductwork pressure sensor, variable frequency adjustment pump group are electrically connected with PID regulator.
Pedestal of the invention are as follows: base body lower end is conically convergent, and convergence end is provided with the water inlet being connected with water inlet pipeConnecting tube, base body top are provided with the second porous disc, and at least 30 circle permeable holes, two adjacent rings are machined on the second porous discPermeable hole Heterogeneous Permutation.
Test cylinder of the present invention is connected and composed by least 3 sections of cylinders.
Pressure measuring unit of the invention are as follows: the one end for surveying pressure connecting tube is connected with test cylinder, and the other end passes through first all the wayValve and third valve are connected with pressure-measuring pipe, another way passes through third valve and the second valve and test barrel pressure pickup phaseConnection.
At least 30 circle permeable holes, two adjacent rings permeable hole Heterogeneous Permutation are machined on the first porous disc of the invention.
Bracket of the invention are as follows: cross section is that the rack body lower part of rectangle is provided at least 6 perpendicular supports, under rack bodyPortion and perpendicular support junction are correspondingly arranged on diagonal brace, are provided with annular brace, the diameter and pedestal of annular brace in the middle part of rack bodyDiameter be adapted.
The simple test method with the vertical seepage deformation tester of coarse-grained soil of the invention large-scale, it is characterised in that including withLower step:
S1, equipment debugging: being completed infiltration testing apparatus, opens simultaneously inlet valve, drain valve, from water inlet pipe to test cylinderWater-filling closes drain valve and exhaust valve, then the high pressure water inspection that simulation test requires until water is overflowed out of drainpipe and gas ventIt is whether intact under test pressure to look into sealing system；
S2, sample preparation are with dress sample: calculating sample dry density ρ as requesteddAnd porosity n, according to preparing volume of sampleSample quantities needed for calculating, hierarchical classification ingredient, dress sample, vibration tamping plate manual zoning rammer densification is real, the layering of permeability test equipmentIt is tightly connected, after the height for reaching requirement, clears up specimen surface, top plate is installed, water flowing is tested, and test method is using infiltrationWater flow applies pressure water from bottom to top；To guarantee sample uniformity and reducing the separation of large or fine granule, every layer of filling sample particleGradation should be consistent, and can also be drunk the moisture for adding about sample mass 3%, be charged, adopt in test chamber again after uniform mixingIt is successively compacted with large scale surface vibrator, sample filling dry density is made to meet design dry density requirement；
Sample dry density ρdIt is as follows with porosity n calculation formula:
Wherein: ρdDry density, g/cm3；mdSample dry mass g, A- Area of Sample, cm2；H- sample actual height, cm；N- porosity, %；ρωThe density of water, g/cm3；Gs- specific gravity of soil partical；
S3, sample saturation: after sample installs, measuring the actual (real) thickness of sample, is then carried out using exhaust head saturationSaturation, makes water pressure water level be slightly above sample basal surface position, then slowly promote water pressure, as pressure of supply water rises, allows waterIt is penetrated into upwards by instrument bottom, is saturated sample slowly, to exclude the air in sample completely, while as water level rises, connectLead to corresponding pressure measuring unit, due to the gas bubble blockage sample hole that test water is isolated, to influence to try during reduction testAccuracy is tested, the temperature of test water is not less than room temperature；
S4, permeability test measurement:
A, according to the fine particle content in sample, tentatively judge the failure mode of sample seepage deformation, select initial infiltration gradientAnd infiltration gradient increment value, infiltration initial gradient are 0.3~0.5, increment value should be controlled according to soil sample property in 0.5~0.8 modelIn enclosing；
B, head is increased step by step by step a regulation, after increasing head every time, record Seepage flow time t, voltage stabling control is no less than30min starts to survey note pressure pipe reading and the reading of graduated cylinder determines seepage flow water Q, surveys and read 3 times under every grade of head, survey read every timeWhen interval be no less than 30min, while survey read water temperature, temperature, calculate the infiltration gradient i and seepage velocity v under heads at different levels
Wherein: i- permeates gradient, and the saturating flow velocity of v-, cm/s, △ H- two piezometric head to be measured are poor, and cm, L- to be measured two surveys pressureManage corresponding seepage paths length, the seepage flow water of cm, Q- within the t time, cm3, t- Seepage flow time, s；
Calculation permeability coefficient kT
Wherein: kTInfiltration coefficient when water temperature is T DEG C, cm/s, k20Infiltration coefficient when water temperature is 20 DEG C, cm/s；
C, draw infiltration gradient i and percolation flow velocity v relation curve to permeate gradient i as ordinate is with percolation flow velocity vAbscissa is plotted on log-log coordinate, while drawing percolation flow velocity v and time relationship t curve, according to infiltration gradient i and is seepedThe slope of flow velocity degree v relation curve starts to change, and observes that fine grained starts to beat or when being taken out of by water flow, it is believed that the sampleReach critical gradient, critical gradient be calculated as follows:
In formula: ikCritical gradient；i2Start to occur gradient when piping；i1Start the gradient for piping previous stage occur；
According to infiltration gradient i and percolation flow velocity v relation curve, as head gradually increases, particulate is constantly flushed away, infiltrationFlow Q becomes larger, and loses anti-permeability strength when head increases to sample, which is known as the destruction gradient of sample, is calculated as follows brokenlyBad gradient:
In formula: iFDestroy gradient；i2The infiltration gradient of '-when destroying；i1'-destroys the infiltration gradient of previous stage；
When soil destruction occurs, when the infiltration gradient of slope bad when is not easy to measure, the infiltration gradient conduct for destroying previous stage is takenThe seepage failure gradient of coarse-grained soil；
S5, inlet valve being closed after the test, extracting remaining water in sample, observation sample variation measures examination as neededHeight after sample test answers timely off-load if any the sample that loading carries and observes bounce situations, unloads top cover, draws remaining on sampleWater, the first porous disc of removal drain water more than instrument, remove sample, take out sample after the test, carry out grading analysis to sampleAnd density test.
Pass through since test method of the invention measures coarse-grained soil according to Darcy's law permeability test principle in water seepage flowWhen sample destruction when integrally floating of infiltration coefficient and the infiltration gradient (piping) that is gradually lost with seepage flow of fine grained and the soil bodyGradient (stream soil), sample partial size is by support engineering project dam body shell material technical requirements maximum particle diameter Dmax≤600mm control, testCylinder segment design and height is adjustable, is provided with porous disc, water flow is entered by pedestal, is buffered in transitional cylinder, by the in cylinderOne porous disc enters test cylinder, and water flow applies pressure from bottom to top, can simulate well and vertically permeate operating condition in Practical Project, rootAccording to test cylinder size be arranged multiple groups pressure measuring unit, measure pressure when different heads, obtain under heads at different levels permeate gradient i,Seepage velocity v, osmotic coefficient kT, the supply of constant head pressure is realized by automatic water supply device system, it can be achieved that automatic supplyThe functions such as pressure, constant pressure, pressurization, substantially increase experimental accuracy, so that large-scale permeability test difficulty becomes greatly easy to operate easyRow is suitable for measuring the vertical seepage deformation test of coarse-grained soil (shot material and sand gravel material of partial size > 600mm).
Detailed description of the invention
Fig. 1 is the structural schematic diagram of one embodiment of the invention.
Fig. 2 is the stepwise schematic views of test cylinder 7 in Fig. 1.
Fig. 3 is the scheme of installation of pressure measuring unit 8 in Fig. 1.
Fig. 4 is the structural schematic diagram of bracket 16 in Fig. 1.
Fig. 5 is the top view of Fig. 4.
Fig. 6 is the A-A cross-sectional view of Fig. 1.
Fig. 7 is the structural schematic diagram of pedestal 15 in Fig. 1.
In figure: 1, water tank；2, variable frequency adjustment pump group；3, pressurized tank；4, ductwork pressure sensor；5, inlet valve；6, it intakesPipe；7, test cylinder；8, pressure measuring unit；9, Water collecting tube；10, top plate；11, drain valve；12, drainpipe；13, graduated cylinder；14, first thoroughlyWater plate；15, pedestal；16, bracket；17, transitional cylinder；18, PID regulator；8-1, pressure-measuring pipe；8-2, the first valve；8-3, secondValve；8-4, test barrel pressure pickup；8-5, third valve；8-6, pressure connecting tube is surveyed；15-1, base body；15-2, secondPorous disc；16-1, diagonal brace；16-2, rack body；16-3, perpendicular support；16-4, annular brace.
Specific embodiment
The present invention is described in further details with reference to the accompanying drawings and examples, but the present invention is not restricted to these implementExample.
Embodiment 1
In Fig. 1~7, a kind of large size of the present invention is simple to match the vertical seepage deformation tester of coarse-grained soil, on bracket 16It is fixedly connected with screw threads for fastening connector and pedestal 15 is installed, further, the bracket 16 of the present embodiment is by diagonal brace 16-1, bracketOntology 16-2, perpendicular support 16-3, annular brace 16-4 are connected and composed, and rack body 16-2 is welded into cross section by square steel or channel steelFor the structure of rectangle, rack body 16-2 lower weld is fixed at least 6 perpendicular support 16-3, the lower part 16-2 and perpendicular under rack bodyThe support junction 16-3 is corresponding to be welded with diagonal brace 16-1, is welded with annular brace 16-4, ring in the middle part of rack body 16-2Shape supports the diameter of 16-4 and the diameter of pedestal 15 to be adapted, and pedestal 15 is by base body 15-1, the second porous disc 15-2 connectionIt constitutes, base body 15-1 is the conical convergent hollow structure in lower end, and convergence end is linked together design and has to be connected with water inlet pipe 6Water inlet connecting tube, be fixedly connected with screw threads for fastening connector at the top of base body 15-1 and the second porous disc 15-2 be installed, theThe permeable hole that at least 30 loop diameters are 5mm, two adjacent rings permeable hole Heterogeneous Permutation and apart are machined on two porous disc 15-210mm is fixedly connected on pedestal 15 with screw threads for fastening connector and is equipped with transitional cylinder 17, is tested water by water inlet connecting tube and is entered bottomSeat 15, collects in 15 cavity of pedestal, until reaching the second porous disc 15-2, enters transitional cylinder by the second porous disc 15-217, and be gradually filled with transitional cylinder 17, make to test the stable rising of water pressure and keep pressure constant state.
17 top of transitional cylinder is fixedly connected with screw threads for fastening connector is equipped with the first porous disc 14, on the first porous disc 14It is machined at least 30 circle permeable holes, two adjacent rings permeable hole Heterogeneous Permutation and at a distance of 10mm is tight with screw thread on the first porous disc 14Connected fitting, which is fixedly connected, is equipped with test cylinder 7, and 7 side wall of test cylinder, two opposite face is symmetrically equidistantly equipped at least 6 groups of survey pressuresUnit 8, the installation number of pressure measuring unit 8 and clipping room away from according to test it needs to be determined that, pressure measuring unit 8 is connected with test cylinder 7,Exhaust pipe is installed on 7 side wall of test cylinder, exhaust valve is installed, the pressure measuring unit 8 of the present embodiment is by pressure-measuring pipe 8- on exhaust pipe1, the first valve 8-2, the second valve 8-3, test barrel pressure pickup 8-4, third valve 8-5, survey pressure connecting tube 8-6 connection structureAt the one end for surveying pressure connecting tube 8-6 is connected with test cylinder 7, and the other end passes through the first valve 8-2 and third valve 8-5 all the wayIt is connected with pressure-measuring pipe 8-1, another way is connected by third valve 8-5 and the second valve 8-3 with test barrel pressure pickup 8-4It is logical, when test, when needing to measure some seepage flow section part head or pressure according to test, open the first valve of corresponding position8-2, the second valve 8-3, third valve 8-5 read the reading of test barrel pressure pickup 8-4 or the reading of pressure-measuring pipe 8-1,Head difference is that two section side-walls pressure-measuring pipes show that level value or test cylinder pressure pass on any two seepage flow section in test cylinderSensor measures the difference that pressure value is scaled head value, and the vertical range between this two section is corresponding seepage paths under the head difference.Test cylinder 7 is threadedly connected part by least three sections of cylinders and is formed by fixedly connecting according to the height of sample in test, cylinderSeam crossing is arranged rubber packing material and carries out sealing, and 7 top of test cylinder is fixedly connected to be equipped with screw threads for fastening connector catchmentsCylinder 9,9 top of Water collecting tube is fixedly connected with screw threads for fastening connector is equipped with top plate 10, is equipped with drainpipe on 9 side wall of Water collecting tube12, drain valve 11 is installed on drainpipe 12, drainpipe 12 is connected with graduated cylinder 13, and when test, graduated cylinder is used after seepage stabilityThe seepage discharge Q that water in certain Seepage flow time section is the period is picked up, cylinder seam crossing setting rubber packing material is stoppedWater.
15 lower part of pedestal is fixedly connected by connecting flange is equipped with water inlet pipe 6, and inlet valve 5 is equipped on water inlet pipe 6, into6 other end of water pipe is connected with pressurized tank 3, and pressurized tank 3 is connected with variable frequency adjustment pump group 2, and 3 pairs of test water flows of pressurized tank rise steadyPressure acts on, and is equipped with ductwork pressure sensor 4, variable frequency adjustment pump group 2 on the pipeline between pressurized tank 3 and variable frequency adjustment pump group 2Be connected with water tank 4, water tank 1 provides water source for this test, pressure sensor 4 by pressure transmitter with PID regulator 18Electrical connection, variable frequency adjustment pump group 2 are connect with PID regulator 18, are perceived ductwork pressure using ductwork pressure sensor 4 and are changed, lead toSignal is fed back to PID regulator 18 by over-voltage power transmitter, and 18 comparison system of PID regulator sets controlling test pressure and carries out phaseThen comparison operation provides corresponding frequency conversion instruction, change the running speed of centrifugal pump, so that the hydraulic pressure of pipe network and control pressureIt is consistent.
The simple test method with the vertical seepage deformation tester of coarse-grained soil of large size of the present invention, including following stepIt is rapid:
S1, equipment debugging: being completed infiltration testing apparatus, opens simultaneously inlet valve, drain valve, exhaust valve, from water inlet pipeIt sees whether to leak to test cylinder water-filling until water is overflowed from drainpipe and exhaust pipe, closes drain valve and exhaust valve, inspectionLook into test barrel and add sealing ring and be under test pressure whether seep dry density leakage, after meeting the requirements, according to testing program andStep is tested, the water pressure that continuous water supply process guarantee test requires, with the accuracy of guarantee test result.
S2, sample preparation and dress sample: dry density is provided according to design and prepares examination needed for volume of sample calculates tentative calculation testSample quantity, hierarchical classification carry out ingredient, dress sample, and vibration tamping plate manually rams densification reality, and the connection of permeability test equipment layered seal reachesTo after the height of requirement, clear up specimen surface, top plate be installed, water flowing tested, test method using infiltration water flow from it is lower toUpper application pressure water；To guarantee sample uniformity and reducing the separation of large or fine granule, every layer of filling sample grain composition should be keptUnanimously, the moisture for adding about sample mass 3% can be also drunk, is charged in test chamber again after uniform mixing, using large scale tableSurface vibration device is successively compacted, and sample filling dry density is made to meet design dry density requirement；
Sample dry density ρdIt is as follows with porosity n calculation formula:
Wherein: ρdDry density, g/cm3；mdSample dry mass g, A- Area of Sample, cm2；H- sample actual height, cm；N- porosity, %；ρωThe density of water, g/cm3；Gs- specific gravity of soil partical；
Sample dry mass mdCalculation formula is as follows:
md=ρd*Ah
Wherein: ρdDry density, g/cm3；mdSample dry mass g, A- Area of Sample, cm2；H- sample actual height, cm；
S3, sample saturation: after sample installs, measuring the actual (real) thickness of sample, is then carried out using exhaust head saturationSaturation, makes water pressure water level be slightly above sample basal surface position, then slowly promote water pressure, as pressure of supply water rises, allows waterIt is penetrated into upwards by instrument bottom, is saturated sample slowly, to exclude the air in sample completely, while as water level rises, connectLead to corresponding pressure measuring unit, due to the gas bubble blockage sample hole that test water is isolated, to influence to try during reduction testAccuracy is tested, the temperature of test water is not less than room temperature；
S4, permeability test measurement:
A, according to the fine particle content in sample, tentatively judge the failure mode of sample seepage deformation, select initial infiltration gradientAnd infiltration gradient increment value, infiltration initial gradient are 0.3~0.5, increment value should be controlled according to soil sample property in 0.5~0.8 modelIn enclosing；When close to critical gradient, infiltration gradient increment value should consider reduction, and when for soil destruction form, numerical value can be appropriateIncrease.
B, head is increased step by step by step a regulation, after increasing head every time, record Seepage flow time t, voltage stabling control is no less than30min starts to survey note pressure pipe reading and the reading of graduated cylinder determines seepage flow water Q, surveys and read 3 times under every grade of head, survey read every timeWhen interval be no less than 30min, while survey read water temperature, temperature, calculate the infiltration gradient i and seepage velocity v under heads at different levels
Wherein: i- permeates gradient, and the saturating flow velocity of v-, cm/s, △ H- two piezometric head to be measured are poor, and cm, L- to be measured two surveys pressureManage corresponding seepage paths length, the seepage flow water of cm, Q- within the t time, cm3, t- Seepage flow time, s；
Calculation permeability coefficient kT
Wherein: kTInfiltration coefficient when water temperature is T DEG C, cm/s, k20Infiltration coefficient when water temperature is 20 DEG C, cm/s；
The water percolating capacity read is surveyed when adjacent 3 times to stablize, and can be increased pressure to next stage head and be continued to measure, repeat above-mentioned stepBy until off-test, reads several 3 close infiltration coefficient average values as test value；
C, draw infiltration gradient i and percolation flow velocity v relation curve to permeate gradient i as ordinate is with percolation flow velocity vAbscissa is plotted on log-log coordinate, while drawing percolation flow velocity v and time relationship t curve, according to curvilinear motion, in timeAdjust every grade of head duration and head it is differential.Started according to infiltration gradient i and the slope of percolation flow velocity v relation curveWhen changing, and observing that fine grained starts to beat or taken out of by water flow, it is believed that the sample has reached critical gradient, is calculated as followsCritical gradient:
In formula: ikCritical gradient；i2Start to occur gradient when piping；i1Start the gradient for piping previous stage occur；
According to infiltration gradient i and percolation flow velocity v relation curve, as head gradually increases, particulate is constantly flushed away, infiltrationFlow Q becomes larger, and loses anti-permeability strength when head increases to sample, which is known as the destruction gradient of sample, is calculated as follows brokenlyBad gradient:
In formula: iFDestroy gradient；i2The infiltration gradient of '-when destroying；i1'-destroys the infiltration gradient of previous stage；
When soil destruction occurs, when the infiltration gradient of slope bad when is not easy to measure, the infiltration gradient conduct for destroying previous stage is takenThe seepage failure gradient of coarse-grained soil；
S5, inlet valve being closed after the test, extracting remaining water in sample, observation sample variation measures examination as neededHeight after sample test answers timely off-load if any the sample that loading carries and observes bounce situations, unloads top cover, draws remaining on sampleWater, the first porous disc of removal drain water more than instrument, remove sample, take out sample after the test, carry out grading analysis to sampleAnd density test.
In experimentation, the various phenomenons of appearance should be observed, such as the muddy degree of water outlet, bubble are emerged, fine grained bounce,Movement is taken out of by water flow, and the soil body suspends, the variation of seepage discharge and piezometric level, and is described in detail, critical when occurringWhen gradient and destruction gradient omen, gradient increment value should be adjusted in time.It can not be further continued for increasing when destruction or head occur for sampleWhen, it can terminate to test.
When measuring infiltration coefficient, the changing value of water level is promoted every time, it should be according to the big of the infiltration coefficient discreet value of testing materialIt is small and different, test can be completed ordinary test change of water level 5 times.