CN105926686A - Centrifugal model testing system and method studying common character of composite foundation and support structure - Google Patents
Centrifugal model testing system and method studying common character of composite foundation and support structure Download PDFInfo
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- CN105926686A CN105926686A CN201610285207.7A CN201610285207A CN105926686A CN 105926686 A CN105926686 A CN 105926686A CN 201610285207 A CN201610285207 A CN 201610285207A CN 105926686 A CN105926686 A CN 105926686A
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D33/00—Testing foundations or foundation structures
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Abstract
The invention discloses a centrifugal model testing system and method studying the common character of a composite foundation and a support structure. The centrifugal model testing system comprises a model box. Foundation soil is arranged in the model box. A support plate used for simulating a support pile is vertically embedded in the foundation soil. A plurality of foundation pile model piles are vertically arranged on one side of the support plate in the model box. A cushion layer is arranged on the top of the foundation soil in which the foundation pile model piles are embedded. The composite foundation is jointly formed by the foundation soil, the foundation pile model piles and the cushion layer. A digging area used for simulating digging is arranged on the other side of the support plate. Testing devices connected with a computer are distributed on the foundation pile model piles and the support plate. A load pressurizing device is arranged at the upper portion of the composite foundation. The whole testing system can be provided with a test system according to the requirements, and the test system is used for testing deformation displacement data and the like of the foundation soil in the composite foundation when a foundation pit is dug. When digging is conducted in the digging area, changes of force or displacement of the composite foundation or the support structure are studied, and practices can be better guided accordingly.
Description
Technical field
The present invention relates to the centrifugal model examination of the test of foundation model, particularly research composite foundation and the common character of supporting construction
Check system and test method.
Background technology
Tradition Geotechnical Engineering laboratory test is carried out under normal gravity condition, owing to or cannot be difficult to reproduce on-the-spot actual size
Condition, is the most often scaled model, and according to soil body weight stress, what scaled model brought is times contracting of soil body degree of depth h, enters
And change soil body self-weight stress field, to the structure with deadweight as primary load, it is impossible to and reflection prototype stress state, cause model
Test cannot simulate the phenomenon that prototype is occurred.
Geotechnical centrifugal model test can the existence of true simulated gravity field, reproduce engineering actual stress state, by numerous scholars
Being generally recognised as carrying out test method most advanced in Geotechnical Engineering research, maximally effective at present, geotechnical centrifugal model test is relative
In prototype measurement, indoor often gravitational field testing machine Numerical Simulations method, there is irreplaceable and unique advantage.
The most ripe with theory of composite foundation, a large amount of multi-rise buildings have employed CFG pile composite foundation.At present, lack both at home and abroad
Weary under lateral excavation condition to the research that existing composite foundation Mechanical Characters of Composite Ground and foundation pit supporting construction thereof are theoretical, make engineering circles
Lacking theory and the method correctly carrying out this type of Design of Excavation Project, designer typically ignores existing composite foundation reinforcement,
Ignore an existing clump of piles and can reduce the advantageous effect of supporting construction displacement, and composite foundation is regarded as undisturbed soil, conservative carrying out
Design of Excavation Project, causes the substantial amounts of wasting of resources, and meanwhile, such to arrange measured data accuracy relatively low, it is impossible to
Reflect Practical Project problem more practically；Additionally, load resisting systems is more complicated in existing test system, excavating device and
The soil layer in excavation simulation district is the most complex, it is impossible to effectively and rapidly realize lateral excavation.
Measurement apparatus is the premise that test is successful, its duty and the accuracy of performance direct relation result of the test
And reliability, even determining the success or failure of single test, the development of measuring instrument, in addition to the enhancing showing as function, also shows
For volume and the minimizing of quality, these development greatly reduce himself impact on result of the test.
In sum, along with maximization, the complication of underground engineering, rely on the way of engineering experience in the past and can not meet and set
Meter, construction requirement, carry out base pit engineering centrifugal model test and can effectively study base pit engineering problem, promotes base pit engineering reason
Opinion is perfect with numerical simulation.
Summary of the invention
Research composite foundation and the centrifugal model test system of the common character of supporting construction and test are it is an object of the invention to provide
Method, by arranging model equipment and test system, is used for the research closing on composite foundation excavation of foundation pit mechanical property,
To setting up to ensure the composite foundation Foundation Pit Support Design theory safely as target and method, there is urgent construction value and length
Remote theory significance.
In order to reach above-mentioned purpose, the present invention adopts the following technical scheme that
Research composite foundation and the centrifugal model test system of the common character of supporting construction, including model casing, set in model casing
Having foundation soil, be vertically embedded with the retaining-plate for simulating support pile in foundation soil, in model casing, the side of retaining-plate vertically sets
Having multiple foundation pile Model Pile, the foundation soil top being embedded with foundation pile Model Pile arranges bed course, foundation soil, foundation pile Model Pile and bed course
Being collectively forming composite foundation, thus composite foundation and retaining-plate jointly exist and more conform to practice of construction environment, at retaining-plate
Opposite side is provided for the excavation area of excavation simulation, is connected with computer with being laid with respectively on retaining-plate in foundation pile Model Pile
Test device, arranges load pressue device on the top of composite foundation；Whole pilot system can be provided for test according to demand
When excavation of foundation pit, the test system of foundation soil deformation displacement data etc. in composite foundation；So when excavation area is excavated,
The change that research composite foundation and the power of supporting construction or displacement produce, thus preferably Guiding Practice.
Further, described test device is included in foundation pile Model Pile the base during assisting acquisition load to apply arranged
The axle stress-strain sheet and being used for of stake Model Pile axle power distribution and foundation soil loading sharing assist acquisition foundation pile Model Pile Bending moment distribution and
The moment of flexure foil gauge of Changing Pattern, is additionally included in the moment of flexure foil gauge that positive and negative both sides, ground, retaining-plate centre position are arranged；Pass through cloth
Put the axle stress-strain sheet in foundation pile Model Pile, it is thus achieved that load applies the distribution of pile axle power and stake soil loading sharing, foundation ditch
The composite foundation foundation pile Model Pile axle power change that excavation causes, Bearing Capacity of Composite Foundation is affected by research excavation；By being arranged in
Moment of flexure foil gauge in foundation pile Model Pile, it is thus achieved that foundation pile Model Pile Bending moment distribution that excavation of foundation pit causes and Changing Pattern, and then
Analyze the foundation pile Model Pile deformation rule with excavation；By the foil gauge being arranged on retaining-plate, it is thus achieved that excavation of foundation pit causes
Soil pressure distribution regular after barricade internal force and Supporting Structure deformation, and retaining-plate of can deriving.
Additionally, axle stress-strain sheet is arranged in foundation pile Model Pile lateral symmetry, moment of flexure foil gauge is arranged in foundation pile Model Pile pile body two
Side.
Further, described test device is additionally included in described foundation soil the multiple for measuring foundation soil force value of setting
Soil pressure sensor；Described soil pressure sensor is T-shaped soil pressure sensor, basis during foundation soil layering is watered and put
Test objective and needs are vertically disposed to each row at composite foundation middle position and close retaining-plate with a determining deviation, according to
Test objective and it needs to be determined that T-shaped soil pressure sensor towards to record test to need the soil pressure force value in direction.
Further, for the ease of observing, model casing is that transparent material is made, and model casing thickness is 3～5mm, described foundation pile
The bottom of Model Pile is coniform, and for coordinating CFG stake, bed course is mattress layer.
Further, the outside at model casing arranges multiple PIV labelling point for providing location reference, it is simple to analyze photograph
The physical location of soil particle pixel in sheet, also includes being installed on multiple video cameras of excavation area in centrifuge crossbeam and model casing,
The misalignment of the soil body can be drawn according to camera head gained photograph pixel analysis.
Further, described mattress layer is coarse sands layer.
Further, the surface-coated in foundation pile Model Pile has the epoxy coating increasing coefficient of friction, with sand in epoxy coating
Son, in order to increase the coefficient of friction on foundation pile Model Pile surface, needs to be coated with a layer thickness at 0.5mm left and right thickness on its surface
Epoxy coating, spills sand, the friction surface that rear formation to be solidified is certain before epoxy coating is done and coagulated, increases coefficient of friction,
Its spacing determine according to acceleration proportionality coefficient according to actual pitch or according to experiment it needs to be determined that, acceleration proportionality coefficient is exactly
Centrifuge accekeration, the centrifuge accekeration determined after considering before test, determine model examination after this accekeration
Each unit in testing need according to the rules with this scale smaller, such as acceleration magnitude for 40, model length dimensional units is just
It should be 1/40 size of prototype.
Further, being the internal earth bag equipped with soil for the excavation area of excavation simulation, earth bag outer surface is provided with and facilitates removal of soil
The suspension ring of bag, such setting greatly facilitates the excavating device excavation to soil layer.
Further, described retaining-plate is aluminium sheet, makes according to bending rigidity equivalence principle, is used for simulating support pile.
Further, described foundation pile Model Pile is CFG stake, is made up according to compressional stiffness equivalence of aluminium-alloy pipe.
Further, the bottom of described foundation pile Model Pile is coniform, it is simple to insert in foundation soil, upper end closure, its length
Determine according to centrifuge acceleration scale.
Described load compression system includes loading air bag, and the air-filled pore of loading air bag exposes and is connected with aerating device, aerating device
Baroceptor is installed and realizes controlling the size of uniform load by controlling air pressure size.
The test method of described centrifugal model test system, specifically comprises the following steps that
1) prepare the centrifugal model test device of composite foundation and the common character of supporting construction, while preparation, lay measurement apparatus；
2) installation test loading system and excavation of foundation pit device；
3) to step 1) in centrifugal model test device, step 2) in excavation of foundation pit device weigh；
4) by step 1) in the lifting of centrifugal model test device to centrifugal basket, video camera and step 1 are installed) in measure
Device connects；
5) start centrifuge, by test system, gather data；
6) classification is further applied load, and successively carries out excavating and gather each test data；
7), after load is stable, excavation of foundation pit device starts excavation, the most repeatedly excavates and gathers each test data；
8), after having tested, the dismounting one by one of plate test loading system, excavation of foundation pit device is carried out.
Further, described step 1) in the preparation side of centrifugal model test device of composite foundation and the common character of supporting construction
Method is as follows:
1-1) use sand rain method that the foundation soil setting thickness is set in model casing；
1-2) in foundation soil, it is vertically arranged retaining-plate, continues in the side of retaining-plate to arrange foundation soil to the thickness set；
Many foundation stake Model Pile 1-3) is set in foundation soil and continues to use sand rain method to foundation soil height and foundation pile Model Pile
Top flushes；
1-4) in step 1) to step 3) carry out while, according to the bucket earthwork make earth bag；
1-5) earth bag is positioned over the opposite side of retaining-plate as excavation area；
1-6) in step 3) complete after or in step 5) complete after, be embedded with foundation pile Model Pile foundation soil top use sand rain
Method arranges coarse sand as mattress layer.
Further, described step 2) in the specifically comprising the following steps that of installation method of loading system
The top that loading air bag 2-1) is placed in mattress layer foundation pile Model Pile is applied evenly load；
2-2) reaction plate is fixed on above loading air bag and loading air bag is retrained, reaction plate support fixed above, and
Frame is fixed with centrifuge；
2-3) load air bag to fix with aerating device.
Further, described step 7) in the specific works step of excavation of foundation pit device be:
3-1) excavating device i.e. loop wheel machine, loop wheel machine primary-secondary beam rotate, drive primary-secondary beam top nut advance or retreat, nut and then
Band movable slider moves back and forth, and moves above earth bag with the electric block that slide block is connected；
3-2) opening electric block switch, earth bag is removed model casing by the suspension ring on earth bag by the suspension hook of electric block；
3-3) closing the motor of primary-secondary beam, open electric block switch, the suspension hook of electric block moves downward, the suspension ring of earth bag
Depart from suspension hook；
3-4) open electric block switch, again rise electric block；
3-5) repeat step 3-1) to step 3-4), until excavation of foundation pit completes.
The invention has the beneficial effects as follows:
1) the assay device principle in the present invention is simple, and structure structure is clear, it is simple to installs and manufactures, cheap.
2) it is collectively forming the composite foundation construction environment as actual condition by foundation soil, foundation pile Model Pile and mattress layer, with
Practice of construction operating mode is consistent, meets the change of foundation soil actual stress, by the research of whole assay device, it is thus achieved that data tool
There is practical study meaning.
3) assay device made according to practice of construction environment, utilizes foundation pile model dress to replace the foundation pile in reality, earth bag to replace
Soil layer, retaining-plate to be excavated simulate support pile, though simple in construction, practicality is high, the beneficially research of actual condition.
4) pilot system that the present invention proposes, it is possible to well and be used for simulating and review composite foundation vertical load transport mechanism
Centrifugal model test match, test device in PIV labelling point, foil gauge position is set, can relatively accurately measure
During excavation of foundation pit, the axle power at foundation pile Model Pile and retaining-plate and moment of flexure equal distribution rule, preferably Guiding Practice work.
5) present invention propose test method, reasonable and simple and convenient, the result of measurement contribute to follow-up to composite foundation with
The research of protection structure common shape.
Accompanying drawing explanation
Fig. 1 is the top view of the present invention；
Fig. 2 is the 1-1 profile of Fig. 1 of the present invention；
Fig. 3 is the 2-2 profile of Fig. 2 of the present invention；
Fig. 4 is the axis stress-strain sheet of the present invention layout drawing in foundation pile Model Pile；
Fig. 5 be in the present invention moment of flexure foil gauge at the layout drawing of foundation pile Model Pile；
Fig. 6 be in the present invention moment of flexure foil gauge at the layout drawing of retaining-plate；
Fig. 7 be in the present invention foil gauge at the layout top view of foundation pile Model Pile；
Fig. 8 be in the present invention foil gauge at the layout side view of foundation pile Model Pile；
Fig. 9 is the arrangement figure of foil gauge in the present invention；
In figure: 1, model casing；2, foundation soil；3, foundation pile Model Pile；4, mattress layer；5, air bag is loaded；6, counter-force
Plate；7, support；8, retaining-plate；9, earth bag；10, L-type changing of the relative positions plate；11, air-filled pore；12, opening；13, connect
Pipe；14, baroceptor；15, charge valve；16, axle stress-strain sheet, 17, moment of flexure foil gauge；
R1, R2, R3, R4 are foil gauge.
Detailed description of the invention
Below in conjunction with the accompanying drawing in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is carried out clear, complete
Describe.
As Figure 1-Figure 2, composite foundation and the centrifugal model test system of the common character of supporting construction, including model casing 1,
For the ease of observing, model casing 1 is made for transparent material, and model casing 1 thickness is 3～5mm, described foundation pile Model Pile 3
Bottom is in coniform.In model casing 1, it is provided with foundation soil 2, in foundation soil 2, is vertically embedded with the supporting for simulating support pile 3
Plate 8, in model casing 1, the side of retaining-plate 8 is vertically provided with multiple foundation pile Model Pile 3, is embedded with the ground of foundation pile Model Pile 3
Soil top arranges mattress layer 4, and foundation soil 2, foundation pile Model Pile 3 and mattress layer 4 are collectively forming composite foundation, thus compoundly
Base and retaining-plate 8 jointly exist and more conform to practice of construction environment, and the opposite side at retaining-plate 8 is provided for excavation simulation
Excavation area, is laterally excavated by excavation of foundation pit unit simulation composite foundation foundation ditch, divides in foundation pile Model Pile 3 with retaining-plate 8
It is not laid with the test device being connected with computer；Whole pilot system can be provided for testing when excavation of foundation pit according to demand,
Expand extruding to composite foundation imposed load by loading air bag 5, draw in composite foundation the data such as foundation soil 2 deformation displacement；
So when excavation area is excavated, the change that research composite foundation and the power of supporting construction or displacement produce, thus more preferably
Guiding Practice.
Mattress layer can also be rigidity, and the concrete of rigid mat usually C7.5-C10 is pounded, and it is applicable to Bao Er great 's
Monolithic floor surface and block surface layer；Flexible cushion (mattress layer) is usually with various scattered materials, such as sand, slag, rubble, ash
Soil etc. is compacted form, and it is applicable to thicker block surface layer.
As shown in Fig. 4～Fig. 8, test device be included in foundation pile Model Pile 3 arrange for assist acquisition load apply process
Middle foundation pile Model Pile 3 axle power is distributed the axle stress-strain sheet 10 with foundation soil loading sharing and is used for assisting acquisition foundation pile Model Pile 3
The moment of flexure foil gauge 11 of Bending moment distribution and Changing Pattern, is additionally included in the moment of flexure that positive and negative both sides, ground, retaining-plate 8 centre position are arranged
Foil gauge 11；By the axle stress-strain sheet 10 being arranged in foundation pile Model Pile 3, it is thus achieved that load applies the distribution of pile axle power
With stake soil loading sharing, the composite foundation foundation pile Model Pile 3 axle power change that excavation of foundation pit causes, research excavation is to composite foundation
Bearing capacity affects；By the moment of flexure foil gauge 11 being arranged in foundation pile Model Pile 3, it is thus achieved that the foundation pile model that excavation of foundation pit causes
Stake 3 Bending moment distributions and Changing Pattern, and then analyze the foundation pile Model Pile 3 deformation rule with excavation；By being arranged in retaining-plate 8
On foil gauge, it is thus achieved that soil pressure after barricade internal force that excavation of foundation pit causes and Supporting Structure deformation, and retaining-plate 8 of can deriving
The regularity of distribution.
Additionally, axle stress-strain sheet 10 is arranged in foundation pile Model Pile 3 lateral symmetry, as it is shown in figure 1, foil gauge is loaded on multiple base
On a few pile in centre of stake Model Pile 3, as Fig. 1 is disposed with the CFG stake 13 of axle stress-strain sheet, moment of flexure foil gauge 11 cloth
Putting in foundation pile Model Pile 3 pile body both sides, all foil gauges are all arranged in full-bridge mode, as it is shown in figure 9, additionally, combine examination
Test purpose and it needs to be determined that moment of flexure foil gauge is towards to record the moment of flexure strain value needing direction.
Test device is additionally included in described foundation soil the multiple soil pressure sensings for measuring foundation soil force value arranged
Device；Described soil pressure sensor 8 is T-shaped soil pressure sensor, according to test objective during foundation soil 2 layering is watered and put
It is vertically disposed to each row at composite foundation middle position and close retaining-plate 8 with a determining deviation, according to test mesh with needs
And it needs to be determined that T-shaped soil pressure sensor towards to record test to need the soil pressure force value in direction.
Arrange multiple PIV labelling point in the outside of model casing 1, PIV labelling point is used for recording in digging process with at least one
The camera head of foundation soil 2 displacement connects, and multiple video cameras are separately mounted on centrifuge crossbeam and excavation area in model casing 1.
Have in foundation pile Model Pile 3 surface-coated and increase the epoxy coating 12 of coefficient of friction, with sand in epoxy coating 12；For
Increase the coefficient of friction on foundation pile Model Pile 3 surface, need to be coated with on its surface a layer thickness epoxy at 0.5mm left and right thickness
Coating 12, epoxy coating 12 dry solidifying before spill sand, to be solidified after form certain friction surface, increase coefficient of friction,
Its spacing determine according to acceleration proportionality coefficient according to actual pitch or according to experiment it needs to be determined that.
It is multiple inside being stacked earth bag 9 equipped with soil for the excavation area of excavation simulation, simulates opening of every layer soil body
Digging, earth bag 9 outer surface is provided with the suspension ring facilitating removal of earth bag 9, and such setting greatly facilitates excavating device to soil layer
Excavation.
For meeting practice of construction environment, described foundation pile Model Pile 3 is CFG stake, by aluminium-alloy pipe according to compressional stiffness equivalence system
Becoming, the bottom of described foundation pile Model Pile 3 is coniform, it is simple to insert in foundation soil 2, upper end closure, its length according to from
Scheming centrifugal acceleration scale determines, centrifugal acceleration before the test according to test it needs to be determined that, typically consider field
Ground area, support pile and CFG stake stake are long, formation condition, indoor model test than the factor such as chi, centrifuge parameters, selected
Centrifugal model test than chi is, i.e. centrifuge setting speed, the every unit determined after centrifuge acceleration in test need by
Regulation carries out reduction conversion, and long measure here is scaled: the length dimension in model=physical length size/centrifugal acceleration.
The test method of described centrifugal model test system, specifically comprises the following steps that
1) prepare the centrifugal model test device of composite foundation and the common character of supporting construction, while preparation, lay measurement apparatus；
2) installation test loading system and excavation of foundation pit device；
3) to step 1) in centrifugal model test device, step 2) in excavation of foundation pit device weigh；And to measuring dress
Put and other equipment check whether normal work；
4) by step 1) in the lifting of centrifugal model test device to centrifugal basket, video camera and step 1 are installed) in measure
Device connects；
5) set accekeration, start centrifuge, by stress section and soil pressure sensor, gather data；Treat CENTRIFUGAL ACCELERATING
After angle value reaches to set g value, stable operation 30min tends towards stability to settlement of foundation, the most every collection data stabilization, and observes
Foundation soil deformation in test；
6) classification is further applied load, and loads at different levels are about 5min stabilization time, carries out after being loaded into default load every time and stablizing
Load loads next time, and gathers test data at analog value；When load reaches to set load, steady load, start foundation ditch
Digging process, carries out ground floor soil excavation；
7), after load is stable, excavation of foundation pit device starts excavation, successively carries out excavating and gather each test data；Excavation
Before and observe sensor acquisition data mode during excavating each soil layer, and carry out preliminary analysis；Soil layer all excavated,
Or when foundation soil deformation is relatively big or barricade deformation is bigger, excavation of foundation pit is no longer carried out, and the most whole excavation of foundation pit has been tested
Become
8) after having tested, air pressure discharges, and shuts down, and after centrifuge stops completely, after number adopts stopping, carrying out device dismounting.
Wherein, described step 1) in composite foundation and the common character of supporting construction centrifugal model test device preparation method such as
Under:
1-1) use sand rain method that the foundation soil setting thickness is set in model casing；
1-2) in foundation soil, it is vertically arranged retaining-plate, continues in the side of retaining-plate to arrange foundation soil to the thickness set；
Many foundation stake Model Pile 1-3) is set in foundation soil and continues to use sand rain method to foundation soil height and foundation pile Model Pile
Top flushes；Foundation pile Model Pile 3 is CFG stake, according to acceleration proportionality coefficient, precalculated CFG stake height h2,
Take foundation soil height h1+ CFG stake height h2About the twice for CFG height, i.e. take h1=h2, and corresponding at model tank wall
Position h1、h2Place's reference mark, inserts in model casing 1 by foundation soil 2 well prepared in advance sand rain method, high at foundation soil
Degree h1Stop sand rain method behind slightly higher place and put sand, utilize thin horizontal line to make uniform CFG stake upper end, arrange that each CFG stake is in ground
In soil 2, thin horizontal line flushes precalculated position h3Lower end, waters sand in model casing 1 again with sand rain method in composite foundation district
In to height h3Lower end；While installing CFG stake, foundation pile Model Pile lateral symmetry arranges axle stress-strain sheet 10,
Moment of flexure foil gauge 11 is arranged in foundation pile Model Pile 3 pile body both sides, and arranges soil pressure sensor 8 in foundation soil 2；
1-4) in step 1) to step 3) carry out while, according to the bucket earthwork conversion make earth bag 9, pass through excavation of foundation pit
Device removal earth bag 9, it is achieved excavation models is excavated.Earth bag 9 uses high intensity cloth to make, and needs to carry out size according to excavation
Design and sew up, retain top cover and do not sew up；
1-5) earth bag 9 is positioned over the opposite side of retaining-plate 8 as excavation area；
1-6) in step 3) complete after or in step 5) complete after, adopt at foundation soil 2 top being embedded with foundation pile Model Pile 3
By sand rain method, coarse sand is set as mattress layer 4, fallen away from, clearance hole size by control and go out Fructus Amomi total flow to reach target phase
To degree of compaction, mattress layer thickness determines according to centrifugal acceleration proportionality coefficient.
Described step 2) in the specifically comprising the following steps that of installation method of loading system
The top that loading air bag 5 2-1) is placed in mattress layer foundation pile Model Pile is applied evenly load；
2-2) reaction plate is fixed on above loading air bag (inflated rubber capsule) 5 and loading air bag 5 is retrained, reaction plate 6
Support fixed above, and support 7 fixes with centrifuge, reaction plate 6, in inverted L shape, is made up of rigid metal plate, is loading
Air bag 5 and reaction plate 6 connect installation L-type changing of the relative positions plate 10 at angle, and reaction plate 6, support 7 and L-type changing of the relative positions plate 10 three are common
Composition reaction rack equipment；Reaction plate is fixed on model casing 1 by otic placode, and the air-filled pore loading air bag 5 from reaction plate and props up
Frame exposes and external aerating device；
Wherein, support 7 is made by rigid metal, generally iron and steel or aluminium alloy, and bottom is fixed with reaction plate 6, top
Fixing with centrifuge, described L-type changing of the relative positions plate 10 is made by rigid metal, and generally iron and steel or aluminium alloy prevents from adding carrier gas
Capsule 5 is extruded after expanding.
2-3) loading air bag 5 to fix with aerating device, aerating device is the aeration tank with baroceptor 14, by adding
The evenly load applying composite foundation is simulated in carrier gas capsule 5 inflation, and in controlled loading air bag 5, the size of air pressure regulates all
The size of cloth load, baroceptor 14 is connected with computer, for display to loading the force value that air bag 5 applies.
Wherein, aeration tank has opening 12 and is connected with the air-filled pore 11 loaded on air bag 5 by connecting tube 13, and
Aeration tank is provided with charge valve 15.
Described step 7) in the specific works step of excavation of foundation pit device be:
3-1) excavating device i.e. loop wheel machine, loop wheel machine primary-secondary beam rotate, drive primary-secondary beam top nut advance or retreat, nut and then
Band movable slider moves back and forth, and moves above earth bag with the electric block that slide block is connected；
3-2) opening electric block switch, earth bag is removed model casing by the suspension ring on earth bag by the suspension hook of electric block；
3-3) closing the motor of primary-secondary beam, open electric block switch, the suspension hook of electric block moves downward, the suspension ring of earth bag
Depart from suspension hook；
3-4) open electric block switch, again rise electric block；
3-5) repeat step 3-1) to step 3-4), until excavation of foundation pit completes.
The manufacture method of centrifugal model test device, specifically comprises the following steps that
1) use sand rain method that the foundation soil 2 setting thickness is set in model casing 1；
2) in foundation soil 2, it is vertically arranged retaining-plate 8, continues in the side of retaining-plate 8 to arrange foundation soil 2 to the thickness set
Degree；
3) arranging many foundation stake Model Pile 3 in foundation soil 2, foundation pile Model Pile 3 is CFG stake, according to acceleration ratio system
Number, precalculated CFG stake height h2, take foundation soil height h1+ CFG stake height h2About the twice for CFG height,
I.e. take h1=h2, and at model tank wall correspondence position h1、h2Place's reference mark, by foundation soil 2 sand rain method well prepared in advance
Insert in model casing 1, at foundation soil height h1Stop sand rain method behind slightly higher place and put sand, utilize thin horizontal line to make uniform in CFG stake
End, arrange each CFG stake in foundation soil 2, thin horizontal line flushes precalculated position h3Lower end, exists again with sand rain method
Sand waters in model casing 1 to height h in composite foundation district3Lower end；While CFG stake is installed, foundation pile Model Pile 3 both sides
It is symmetrical arranged axle stress-strain sheet 10, arranges moment of flexure foil gauge 11 in foundation pile Model Pile 3 pile body both sides, and set in foundation soil 2
Put soil pressure sensor 8；
Wherein, centrifugal acceleration before the test according to test it needs to be determined that, typically consider site area, support pile and CFG
Stake is long in stake, formation condition, indoor model test than the factor such as chi, centrifuge parameters, selected centrifugal model test than chi is,
I.e. centrifuge setting speed, after determining centrifuge acceleration, the every unit in test needs to be carried out in accordance with regulations reduction conversion, this
In long measure be scaled: the length dimension in model=physical length size/centrifugal acceleration.
4) in step 1) to step 3) carry out while, according to the bucket earthwork conversion make earth bag 9, filled by excavation of foundation pit
Put removal earth bag 9, it is achieved excavation models is excavated.Earth bag 9 uses high intensity cloth to make, and needs to carry out size according to excavation and sets
Count and sew up, retain top cover and do not sew up；
5) earth bag 9 is positioned over the opposite side of retaining-plate 8 as excavation area；
6) in step 3) complete after or in step 5) complete after, adopt at foundation soil 2 top being embedded with foundation pile Model Pile 3
By sand rain method, coarse sand is set as mattress layer 4, fallen away from, clearance hole size by control and go out Fructus Amomi total flow to reach target phase
To degree of compaction, mattress layer thickness determines according to centrifugal acceleration proportionality coefficient.
The above is only the preferred embodiment of the present invention, it is noted that come for those skilled in the art
Saying, under the premise without departing from the principles of the invention, it is also possible to make some improvements and modifications, these improvements and modifications also should regard
For protection scope of the present invention.
Claims (10)
1. research composite foundation and the centrifugal model test system of the common character of supporting construction, it is characterised in that include model casing,
In model casing, it is provided with foundation soil, in foundation soil, is vertically embedded with the retaining-plate for simulating support pile, retaining-plate in model casing
Side be vertically provided with multiple foundation pile Model Pile, the foundation soil top being embedded with foundation pile Model Pile arranges bed course, foundation soil, foundation pile
Model Pile and bed course are collectively forming composite foundation, and the opposite side at retaining-plate is provided for the excavation area of excavation simulation, at foundation pile
Model Pile be laid with the test device being connected with computer on retaining-plate respectively, also include the lotus being located at the top of composite foundation
Carry compression system.
2. centrifugal model test device as claimed in claim 1, it is characterised in that described test device is included in foundation pile mould
The distribution of foundation pile Model Pile axle power and the axle power of foundation soil loading sharing during assisting acquisition load to apply arranged in type stake
Foil gauge and for assisting acquisition foundation pile Model Pile Bending moment distribution and the moment of flexure foil gauge of Changing Pattern, is additionally included in retaining-plate
Between the moment of flexure foil gauge that arranges of positive and negative both sides, ground, position.
3. centrifugal model test device as claimed in claim 1 or 2, it is characterised in that described test device is additionally included in
The multiple soil pressure sensors for measuring foundation soil force value arranged in described foundation soil, described bed course is mattress layer.
4. centrifugal model test device as claimed in claim 1, it is characterised in that multiple use is set in the outside of model casing
In providing the PIV labelling point of location reference, also include being installed on multiple video cameras of excavation area in centrifuge crossbeam and model casing.
5. centrifugal model test device as claimed in claim 1 or 2, it is characterised in that for the excavation area of excavation simulation
For inside equipped with native earth bag, earth bag outer surface is provided with the suspension ring facilitating removal of earth bag.
6. centrifugal model test device as claimed in claim 1 or 2, it is characterised in that described load compression system includes
Loading air bag, the air-filled pore of loading air bag exposes and is connected with aerating device, and aerating device is provided with baroceptor for controlling
The size of uniform load.
7. the test method of the centrifugal model test system as according to any one of claim 1-6, it is characterised in that concrete
Step is as follows:
1) prepare the centrifugal model test device of composite foundation and the common character of supporting construction, while preparation, lay measurement apparatus；
2) installation test loading system and excavation of foundation pit device；
3) to step 1) in centrifugal model test device, step 2) in excavation of foundation pit device weigh；
4) by step 1) in the lifting of centrifugal model test device to centrifugal basket, video camera and step 1 are installed) in measure
Device connects；
5) start centrifuge, by test system, gather data；
6) classification is further applied load, and successively carries out excavating and gather each test data；
7), after load is stable, excavation of foundation pit device starts excavation, the most repeatedly excavates and gathers each test data；
8), after having tested, the dismounting one by one of plate test loading system, excavation of foundation pit device is carried out.
8. centrifugal model test method as claimed in claim 7, it is characterised in that described step 1) in composite foundation with
The preparation method of the centrifugal model test device of the common character of supporting construction is as follows:
1-1) use sand rain method that the foundation soil setting thickness is set in model casing；
1-2) in foundation soil, it is vertically arranged retaining-plate, continues in the side of retaining-plate to arrange foundation soil to the thickness set；
Many foundation stake Model Pile 1-3) is set in foundation soil and continues to use sand rain method to foundation soil height and foundation pile Model Pile
Top flushes；
1-4) in step 1) to step 3) carry out while, according to the bucket earthwork make earth bag；
1-5) earth bag is positioned over the opposite side of retaining-plate as excavation area；
1-6) in step 3) complete after or in step 5) complete after, be embedded with foundation pile Model Pile foundation soil top use sand rain
Method arranges coarse sand as mattress layer.
9. centrifugal model test method as claimed in claim 7, it is characterised in that described step 2) in loading system
Specifically comprising the following steps that of installation method
The top that loading air bag 2-1) is placed in mattress layer foundation pile Model Pile is applied evenly load；
2-2) reaction plate is fixed on above loading air bag and loading air bag is retrained, reaction plate support fixed above, and
Frame is fixed with centrifuge；
2-3) load air bag to fix with aerating device.
10. centrifugal model test method as claimed in claim 7, it is characterised in that described step 7) in excavation of foundation pit dress
The specific works step put is:
3-1) excavating device i.e. loop wheel machine, loop wheel machine primary-secondary beam rotate, drive primary-secondary beam top nut advance or retreat, nut and then
Band movable slider moves back and forth, and moves above earth bag with the electric block that slide block is connected；
3-2) opening electric block switch, earth bag is removed model casing by the suspension ring on earth bag by the suspension hook of electric block；
3-3) closing the motor of primary-secondary beam, open electric block switch, the suspension hook of electric block moves downward, the suspension ring of earth bag
Depart from suspension hook；
3-4) open electric block switch, again rise electric block；
3-5) repeat step 3-1) to step 3-4), until excavation of foundation pit completes.
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