A kind of gradient confined pressure down tube sunk pile simulation test device and method
Technical field
The present invention relates to a kind of gradient confined pressure down tube sunk pile simulation test device and method, in belonging to building engineering field
Pile foundation technical field.
Background technology
Build with room, the continuous development that traffic, harbour, oil and wind energy project are built, pile tube is increasingly being applied to
In architectural engineering and offshore engineering.In pile sinking penetration process, nearby soil particle will be moved and mutual pile body open-end pipe pile
, while pile-end soil body is poured in formed in pile tube soil plug, that is, there is soil plug effect and soil compaction effect in extruding.With the increasing of depth of penetration
Plus, the increase of soil body lateral stress, stake is outer and stake inside sliding block gradually increases, and the soil body radially extruded is more and more.Meanwhile,
Due to the increase of cladding earth pressure, the extrusion stress that deep soil is subject to is bigger than the shallow-layer soil body.Pile tube is in static pressure or pile vibrosinking
During disturbance will certainly be produced to surrounding soil, reinvent and squeezing action, stake week nearby modulus of shearing, density of the soil body etc.
Parameter inevitably changes, and makes soil around pile diametrically present inhomogeneities.Additionally, soil plug is in pile tube injection
Disturbed by very big so that the intensity of soil portion's soil body beyond the Great Wall is relatively low, also less with the collateral resistance between pile tube inwall, is being in vertically
Existing anisotropism.
At present, indoor model test is advised by the various sensors of arrangement to the development such as penetration resistance, soil pressure against piles mostly
Rule is measured, or auxiliary change to soil displacement field in visualization window is observed.However, above-mentioned conventional 1g scaled models examination
The soil stress level for testing offer is very low, it is impossible to simulate the true stress state at soil layer different depth.Because pile tube injection is received
The impact of lateral stress and soil plug effect, under low confined pressure the soil body often show it is strong cut swollen and strain softening phenomenon, cause
Factor and the physical presence larger differences such as soil disturbance scope, level of disruption and soil plug height.Before making the present invention, patent of invention
" loading of static pressure model test of pile and measurement apparatus " (CN103835323A) disclose a kind of loading of static pressure model test of pile
And measurement apparatus;Pile tube as the friction cylinder of Double lumen intubation system, with quiet microcomputer automatic data collection end resistance is visited by the invention
And collateral resistance.Patent of invention " assay device and its method of static pressure steel-pipe pile pile driving process under the conditions of simulation confined pressure "
(CN105424487A) assay device and its method of static pressure steel-pipe pile pile driving process under the conditions of a kind of simulation confined pressure are disclosed;Should
Invention by steel-pipe pile injection in the rock sample in pressure chamber, is acted on improved triaxial apparatus with the hydraulic pressure in pressure chamber
Confined pressure condition of the simulation stake in actual rock stratum, obtains Changing Pattern of the axle power with pile sinking displacement.However, foregoing invention cannot
In-situ stress level and distribution characteristicss of the simulation natural rock-filled under Gravitative Loads, and lack to soil around pile and the stake core soil soil body
The test of matter dynamic evolution.
The content of the invention
The present invention is intended to provide a kind of gradient confined pressure down tube sunk pile simulation test device and method, are the simulation of pile tube pile sinking
Real ambient stress is provided, and realizes the synchronous dynamic test of penetration resistance, soil plug effect and soil compaction effect.
The invention provides a kind of gradient confined pressure down tube sunk pile simulation test device, including counter-force bracing frame, plus carry
Put, wave velocity testing device, model pile tube, confined pressure simulated assembly;
The counter-force bracing frame includes reaction frame and counter-force crossbeam, and counter-force beam vertical is arranged on the middle part of reaction frame;
Charger includes two pairs of drive gears, sawtooth depression bar and bearing plates, and two pairs of drive gears are placed on counter-force crossbeam, drives
By motor control, sawtooth depression bar is separately positioned between two drive gears gear, and sawtooth depression bar passes through counter-force crossbeam, sawtooth
Depression bar bottom is provided with bearing plate;During loading, using motor drive drive gear rotation, by mechanical conductive drive sawtooth depression bar and
Bearing plate moves vertically;Ergometer is provided between sawtooth depression bar and bearing plate, for measuring the penetration resistance of pile tube;Bearing plate
End is provided with illuminator, and laser range finder is fixed with reaction frame medial wall, and laser range finder is corresponding in opposite directions with illuminator to be set
Put;The bearing plate is inverted T shape Circular plate structure, and center is provided with hole;
The model pile tube includes inner sleeve, trocar sheath, stake inner sleeve, plunger tip screw rod and stake terminal block block, and model pile tube is deeply native
In vivo portion, is evenly equipped with thereon wave velocity testing device;
The model pile tube inner side is stake inner sleeve, and sleeve welded top doughnut-shaped steel plate, stake inner sleeve bottom is fastened on a terminal block
In block;The bearing plate connection of stake inner sleeve, doughnut-shaped steel plate and upper end;Plunger tip screw rod is provided with inside stake inner sleeve, on plunger tip screw rod
End is fixed on counter-force crossbeam, and bearing plate and pile tube are sequentially passed through downwards, and bottom contacts with the soil body;In loading procedure, by adjusting
Section top nut control screw rod embedded depth, so as to obtain the soil plug of differing heights;
The wave velocity testing device include it is some along pile tube inner and outer surfaces differing heights it is arranged in pairs excite unit and receive unit,
The shear wave velocity of stake core soil and Pile side soil is measured respectively;Each two excites unit and receives unit's one group of test cell of composition,
And by the external test device of flexure element holding wire;Wherein, unit is excited radially to be arranged symmetrically respectively with unit is received in stake, stake side
Excite unit and receive unit and then closely arrange in pairs up and down on the outside of pile tube along same axis;
Groove is provided between the inside and outside sleeve pipe, flexure element holding wire is passed through from the groove;Stake inner sleeve and test cell bottom
Block is contacted, and is not contacted with inner sleeve;
The confined pressure simulated assembly includes confined pressure ring, guide pipe, rubber membrane, the latex film of several vertical stackings, confined pressure simulation
Component is fixed on pedestal top, is fixed by outer shroud bolt connection each other;It is provided between two neighbouring confined pressure rings
Water injection hole, the external hydraulic control device of water injection hole;The confined pressure ring connects shape by a pair of concentric drums by upper and lower annular cover plate
Integral structure, the cavity for surrounding is used as pressure chamber;
Confined pressure collar into inner space adopt latex membrane closure, latex film inner side to be provided with rubber pattern, rubber pattern parcel soil sample, together
When the upper and lower ring edge of latex film is individually fixed in into upper and lower annular cover plate outer surface by screw and grooved metal gasket, form sealing
Fluid-tight cavity structure.
In said apparatus, the stake inner sleeve is made using hollow steel pipe, is sheathed on inside pile tube, and diameter is not contacting stake
Interior flexure element is defined, and length is long with stake consistent, it is to avoid soil plug is directly contacted with flexure element in stake and causes it to extrude in pile driving process
Destruction, and aid in plunger tip screw rod control stake core soil plug height;Doughnut-shaped steel plate size and bearing plate bottom chi at the top of stake inner sleeve
It is very little consistent, along the circumferential direction reserve some bolts hole, and packing ring is set thereunder, by bolt by packing ring, doughnut-shaped steel plate and
Bearing plate is linked to be entirety, realizes to stake inner sleeve power transmission.
In said apparatus, described to excite unit and receive unit for piezoelectric ceramic bending element, flexure element logarithm and spacing can bases
Test objective and specific requirement are selected.
In said apparatus, the flexure element embedment soil body depth is 5mm, and operating frequency is 5 ~ 25kHz;Stake lateral bend unit is
Using horizontal polarization direction, every group of test cell adopts identical polarization direction in stake;Block is set below flexure element, is prevented
Soil body filling when stake inner sleeve is removed damages flexure element, while preventing an inner sleeve to be likely to occur lateral deflection unstability;
In said apparatus, excite unit in stake side and receive the pile cutoff overcoat shock absorbing ring between unit, made using super quiet fragrant deadening felt,
Avoid the soil body for exciting from vibrating to propagate along pile body and cause measurement error.
In said apparatus, 90 degree of orthogonal directions of inner sleeve tube outer surface of the model pile tube open up respectively two pairs of depth and are
5mm, width is the groove of 20mm, and from the bottom flexure element stake top is through to, and for the inside and outside flexure element of spud pile and draws
Holding wire;Stake top is fastened in the packing ring of bearing plate bottom surface, is realized to pile tube power transmission.
In said apparatus, the inside and outside sleeve pipe of the pile tube is coaxially bonded, the stake terminal block block of stake bottom adhesion 20 ~ 40mm of height, is prevented
Only in stake penetration process there is the shearing changing of the relative positions in inside and outside sleeve pipe along contact surface;Stake terminal block block external diameter is consistent with model pile tube external diameter, interior
Footpath is consistent with stake inner sleeve, and medial surface is arranged to cutting shoe, and to facilitate soil is cut, and opens up an annular slot in its top surface, for card
If stake inner sleeve.
The invention provides a kind of gradient confined pressure down tube sunk pile simulation experiment method, comprises the following steps:
A. soil sample makes.Rubber membrane is surrounded sleeve rubber bar first is fixed on the boss of pedestal, if surface ring set
Dry hollow steel cylinder is simultaneously bolted to be formed and holds film cylinder, and backing cylinder edge will be turned to outside rubber membrane top edge, makes rubber membrane
Integrally be laid in backing cylinder inwall;Then placement in layers soil sample, until predetermined altitude, and add the top of center drilling in native face
Lid, while by rubber membrane varus, with rubber bar colligation on top cover;Backing cylinder is finally dismantled, model soil sample completes.
B., confined pressure simulated assembly is installed.Several confined pressure rings made vertically are laminated, and are set in soil sample outside,
Ensure that its inner core side wall latex film is contacted with soil in ring, top surface adds guide pipe.Between adjacent confined pressure ring, bottom confined pressure ring and base
Between seat, and it is fixed with bolts between top confined pressure ring and guide pipe.
C. model pile tube makes.Groove is opened up in the inner sleeve tube outer surface of model pile tube, unit will be received and first installation is excited
In the hole position reserved to pile tube, epoxide-resin glue fixed closed is used;Wedge-shaped catch is pasted below flexure element, by each flexure element letter
Number wire routing is drawn in groove and from stake top, external test device;Finally splicing bonding inner sleeve, trocar sheath and it is super it is quiet it is fragrant every
Sound felt, while in stake end adhesion collar stop.
D. model is installed.Model pile tube is stood on into pile sinking position along guide pipe, stake end flushes with native face, and stake top is embedded in
In packing ring, and stake inner sleeve is placed in model pile tube and snap ring by stake terminal block block is fixed;Subsequently by stake inner sleeve, packing ring
And bearing plate is bolted, while plunger tip screw rod is stretched into into an inner sleeve, bottom contacts with native face.Simultaneously by laser ranging
Instrument is fixed on reaction frame inner side, and illuminator is fixed on into bearing plate end, charger is fixed on counter-force crossbeam, by dynamometry
Meter is fixed between bearing plate and sawtooth depression bar.
E. confined pressure is applied.According to each confined pressure ring hydraulic pressure that requirement of experiment sets, using the external pressurized control dress of water injection hole
The water filling into confined pressure ring is put, by latex film by pressure transmission to soil sample, soil in-situ stress state is simulated.
F. pile tube injection.First each sensor is debugged, reset;Then pass through motor-driven gear to apply pile tube
Plus load, in making the slow injection soil of model pile tube, using sensor acquisition data;After injection to set depth, dynamometry is removed
Meter, sawtooth depression bar and bearing plate are directly connected to, and motor reversely rotates gear and detaches stake inner sleeve, make core soil and a flexure element
Contact;After soil plug height adjustment is stable, flexure element is run successively, the shear wave velocity of soil around pile after soil compaction during pile driving and soil plug is entered
Row measurement.
In said method, if the film cylinder that holds vertically is laminated by dried layer hollow steel cylinder, internal diameter and confined pressure ring internal diameter
Unanimously, and by outer shroud bolt connection fix;When soil sample makes, the rubber pattern by pedestal is enclosed within advance and with rubber bar colligation is applied
Cylinder inboard wall is located at, subsequent placement in layers soil sample adds top cover when design height is filled to, and colligation rubber membrane is removed hold afterwards
Film cylinder.
Beneficial effects of the present invention:
(1)Real soil body lateral stress environment is provided for pile tube pile sinking simulation process, and polytype confined pressure can be applied
Gradient, overcoming conventional 1g model tests cannot simulate the defect of in-situ stress state;
(2)Stake core soil and soil around pile shear wave velocity in open-end pipe pile penetration process are measured using flexure element, is research pipe
Soil nature dynamic evolution provides experimental test means in stake soil plug and soil compaction effect;With horizontal displacement, hole in existing experimental technique
Pressure and earth pressure test combine, and will form the pile tube pile sinking characteristic test device of complete set;
(3)The present invention is further applied load using motor-driven gear mode to pile tube, controls piling speed by microcomputer, it is ensured that stake
Body uniformly sinks, and convenient and fast loading, precision is higher.
Description of the drawings
Fig. 1 is the structural representation of this device;
Fig. 2 is the top view of Fig. 1;
Fig. 3 is flexure element arrangement profilograph in stake;
Fig. 4 is a lateral bend unit arrangement profilograph;
Fig. 5 is the profile of pile tube A-A along Fig. 4(Amplify);
Fig. 6 is the enlarged diagram that pile tube bearing plate is connected with upper and lower part;
Fig. 7 is the structural representation of confined pressure ring;
Fig. 8 is the structural representation of backing cylinder;
In figure:1st, reaction frame, 2, sawtooth depression bar, 3, drive gear, 4, counter-force crossbeam, 5, laser range finder, 6, illuminator, 7, survey
Power meter, 8, bearing plate, 9, packing ring, 10, plunger tip screw rod, 11, stake inner sleeve, 12, excite unit, 13, receive unit, 14, wedge-shaped catch,
15th, trocar sheath, 16, inner sleeve, 17, holding wire, 18, super quiet fragrant deadening felt, 19, stake terminal block block, 20, guide pipe, 21, outer shroud spiral shell
Bolt, 22, confined pressure ring, 23, latex film, 24, grooved metal gasket, 25, screw, 26, water injection hole, 27, top cover, 28, rubber membrane, 29, soil
Sample, 30, pedestal.
Specific embodiment
The present invention is further illustrated below by embodiment, but is not limited to following examples.
Embodiment 1:
As shown in Fig. 1 ~ 7, a kind of gradient confined pressure down tube sunk pile simulation test device, including counter-force bracing frame, charger, ripple
Fast test device, model pile tube, confined pressure simulated assembly;
The counter-force bracing frame includes reaction frame 1 and counter-force crossbeam 4, and counter-force crossbeam 4 is vertically set on the middle part of reaction frame 1;
Charger includes two pairs of drive gears 3, sawtooth depression bar 2 and bearing plates 8, and two pairs of drive gears 3 are placed in counter-force crossbeam 4
On, by motor control, sawtooth depression bar 2 is separately positioned between two drive gears 3 drive gear 3, and sawtooth depression bar 2 is through instead
Power crossbeam 4, the bottom of sawtooth depression bar 2 is provided with bearing plate 8;During loading, drive gear 3 is driven to rotate using motor, by machinery biography
The dynamic sawtooth depression bar 2 of conduction band and bearing plate 8 move vertically;Ergometer 7 is provided between sawtooth depression bar 2 and bearing plate 8, for measuring
The penetration resistance of pile tube;The end of bearing plate 8 is provided with illuminator 6, and reaction frame 1 is fixed with laser range finder 5, laser on medial wall
Diastimeter 5 is correspondingly arranged in opposite directions with illuminator 6;The bearing plate 8 is inverted T shape Circular plate structure, and center is provided with hole;
The model pile tube includes inner sleeve 16, trocar sheath 15, stake inner sleeve 11, plunger tip screw rod 10 and stake terminal block block 19, model
Pile tube gos deep into inside soil body, and wave velocity testing device is evenly equipped with thereon;
The model pile tube inner side is stake inner sleeve 11, and sleeve welded top doughnut-shaped steel plate, the bottom of stake inner sleeve 11 is fastened on stake
In terminal block block 19;The bearing plate 8 of stake inner sleeve 11, doughnut-shaped steel plate and upper end connects;Plunger tip screw rod is provided with inside stake inner sleeve 11
10, the upper end of plunger tip screw rod 10 is fixed on counter-force crossbeam 4, and bearing plate 8 and pile tube are sequentially passed through downwards, and bottom contacts with the soil body;
In loading procedure, screw rod embedded depth is controlled by adjusting top nut, so as to obtain the soil plug of differing heights;
The wave velocity testing device include it is some along pile tube inner and outer surfaces differing heights it is arranged in pairs excite unit 12 and receive unit
13, the shear wave velocity of stake core soil and Pile side soil is measured respectively;Each two excites unit 12 and receives unit 13 and constitutes one group of survey
Examination unit, and by the external test device of flexure element holding wire 17;Wherein, unit 12 is excited in stake and unit 13 is received respectively radially
It is arranged symmetrically, stake side excites unit 12 and receives unit 13 and then closely arranges in pairs up and down on the outside of pile tube along same axis(See Fig. 3
With 4);
Groove is provided between the inside and outside sleeve pipe, flexure element holding wire 17 is passed through from the groove;Under stake inner sleeve and test cell
Portion's block contact, does not contact with inner sleeve;
The confined pressure simulated assembly includes confined pressure ring 22, guide pipe 20, rubber membrane 28, the latex film 23 of several vertical stackings,
Confined pressure simulated assembly is fixed on the top of pedestal 30, is connected by outer collar bolt 21 each other;Neighbouring two enclose
Water injection hole 26, the external hydraulic control device of water injection hole are provided between pressure ring;The confined pressure ring 22 by a pair of concentric drums by it is upper,
Lower annular cover plate connects to form overall structure, and the cavity for surrounding is used as pressure chamber;
Confined pressure collar into inner space closed using latex film 23, the inner side of latex film 23 is provided with rubber pattern 28, and rubber pattern 28 is wrapped
Soil sample 29 is wrapped up in, while ring edge passes through screw 25 and grooved metal gasket 24 is individually fixed in upper and lower ring cover about 23 by latex film
Plate outer surface, forms the fluid-tight cavity structure of sealing.
In said apparatus, the stake inner sleeve 11 is made using hollow steel pipe, is sheathed on inside pile tube, and diameter is not contacting
Flexure element is defined in stake, and length is long with stake consistent, it is to avoid soil plug is directly contacted with flexure element in stake and causes it to squeeze in pile driving process
Crush bad, and aid in plunger tip screw rod control stake core soil plug height;Doughnut-shaped steel plate size and bearing plate bottom at the top of stake inner sleeve
Consistent size, along the circumferential direction reserves some bolts hole, and arranges packing ring thereunder, by bolt by packing ring, doughnut-shaped steel plate
It is linked to be entirety with bearing plate, realizes to stake inner sleeve power transmission.
In said apparatus, described to excite unit 12 and receive unit 13 for piezoelectric ceramic bending element, flexure element logarithm and spacing can
Selected according to test objective and specific requirement.
In said apparatus, the flexure element embedment soil body depth is 5mm, and operating frequency is 5 ~ 25kHz;Stake lateral bend unit is
Using horizontal polarization direction, every group of test cell adopts identical polarization direction in stake;Block is set below flexure element, is prevented
Soil body filling when stake inner sleeve is removed damages flexure element, while preventing an inner sleeve to be likely to occur lateral deflection unstability;
In said apparatus, excite unit 12 in stake side and receive the pile cutoff overcoat shock absorbing ring between unit 13, using super quiet fragrant deadening felt
18 make, it is to avoid the soil body vibration for exciting is propagated along pile body and causes measurement error.
Flexure element test philosophy:Excite unit to send vibration, propagate to receive unit via soil sample, so as to measure the shearing of soil sample
Velocity of wave.In Fig. 4, excite unit to send shearing wave Jing Pile side soils and propagate to receive unit, super quiet fragrant deadening felt is to prevent shearing wave from stake
Interior propagation, so as to affect test accuracy.
In said apparatus, 90 degree of orthogonal directions of inner sleeve tube outer surface of the model pile tube open up respectively two pairs of depth and are
5mm, width is the groove of 20mm, and from the bottom flexure element stake top is through to, and for the inside and outside flexure element of spud pile and draws
Holding wire;Stake top is fastened in the packing ring of bearing plate bottom surface, is realized to pile tube power transmission.
In said apparatus, the inside and outside sleeve pipe of the pile tube is coaxially bonded, the stake terminal block block of stake bottom adhesion 20 ~ 40mm of height, is prevented
Only in stake penetration process there is the shearing changing of the relative positions in inside and outside sleeve pipe along contact surface;Stake terminal block block external diameter is consistent with model pile tube external diameter, interior
Footpath is consistent with stake inner sleeve, and medial surface is arranged to cutting shoe, and to facilitate soil is cut, and opens up an annular slot in its top surface, for card
If stake inner sleeve.
The invention provides a kind of gradient confined pressure down tube sunk pile simulation experiment method, comprises the following steps:
A. soil sample makes.Rubber membrane is surrounded sleeve rubber bar first is fixed on the boss of pedestal, if surface ring set
Dry hollow steel cylinder is simultaneously bolted to be formed and holds film cylinder, and backing cylinder edge will be turned to outside rubber membrane top edge, makes rubber membrane
Integrally be laid in backing cylinder inwall;Then placement in layers soil sample, until predetermined altitude, and add the top of center drilling in native face
Lid, while by rubber membrane varus, with rubber bar colligation on top cover;Backing cylinder is finally dismantled, model soil sample completes.
B., confined pressure simulated assembly is installed.Several confined pressure rings made vertically are laminated, and are set in soil sample outside,
Ensure that its inner core side wall latex film is contacted with soil in ring, top surface adds guide pipe.Between adjacent confined pressure ring, bottom confined pressure ring and base
Between seat, and it is fixed with bolts between top confined pressure ring and guide pipe.
C. model pile tube makes.Groove is opened up in the inner sleeve tube outer surface of model pile tube, unit will be received and first installation is excited
In the hole position reserved to pile tube, epoxide-resin glue fixed closed is used;Wedge-shaped catch is pasted below flexure element, by each flexure element letter
Number wire routing is drawn in groove and from stake top, external test device;Finally splicing bonding inner sleeve, trocar sheath and it is super it is quiet it is fragrant every
Sound felt, while in stake end adhesion collar stop.
D. model is installed.Model pile tube is stood on into pile sinking position along guide pipe, stake end flushes with native face, and stake top is embedded in
In packing ring, and stake inner sleeve is placed in model pile tube and snap ring by stake terminal block block is fixed;Subsequently by stake inner sleeve, packing ring
And bearing plate is bolted, while plunger tip screw rod is stretched into into an inner sleeve, bottom contacts with native face.Simultaneously by laser ranging
Instrument is fixed on reaction frame inner side, and illuminator is fixed on into bearing plate end, charger is fixed on counter-force crossbeam, by dynamometry
Meter is fixed between bearing plate and sawtooth depression bar.
E. confined pressure is applied.According to each confined pressure ring hydraulic pressure that requirement of experiment sets, using the external pressurized control dress of water injection hole
The water filling into confined pressure ring is put, by latex film by pressure transmission to soil sample, soil in-situ stress state is simulated.
F. pile tube injection.First each sensor is debugged, reset;Then pass through motor-driven gear to apply pile tube
Plus load, in making the slow injection soil of model pile tube, using sensor acquisition data;After injection to set depth, dynamometry is removed
Meter, sawtooth depression bar and bearing plate are directly connected to, and motor reversely rotates gear and detaches stake inner sleeve, make core soil and a flexure element
Contact;After soil plug height adjustment is stable, flexure element is run successively, the shear wave velocity of soil around pile after soil compaction during pile driving and soil plug is entered
Row measurement.
In said method, if the film cylinder that holds vertically is laminated by dried layer hollow steel cylinder, internal diameter and confined pressure ring internal diameter
Unanimously, and by outer shroud bolt connection fix;When soil sample makes, the rubber pattern by pedestal is enclosed within advance and with rubber bar colligation is applied
Cylinder inboard wall is located at, subsequent placement in layers soil sample adds top cover when design height is filled to, and colligation rubber membrane is removed hold afterwards
Film cylinder.The structure for holding film cylinder is as shown in Figure 8.