CN103898930B - Prestressed concrete pipe pile horizontal bearing attribute testing model and modeling method - Google Patents

Abstract

The invention discloses a kind of prestressed concrete pipe pile horizontal bearing attribute testing model and modeling method, model includes a model groove, is provided with the cushion cap for carrying Model Pile in described model groove, and the upper end of Model Pile is embedded in cushion cap；Described model groove be arranged over one that be connected with reaction frame and to cushion cap implement vertical force vertical loading system, it is provided with connected and to cushion cap carrying out horizontal power horizontal addload system inside model groove, and is provided with monitoring device in described cushion cap, Model Pile and loading system.The present invention provides a kind of loading condition requirement that can preferably control load on pile foundation test, simulates the practical working situation of pile foundation more realistically, probes into pile tube single pile and the clump of piles assay device of bearer properties under horizontal loads.

Description

Prestressed concrete pipe pile horizontal bearing attribute testing model and modeling method

Technical field

The present invention relates to a kind of civil engineering test model and method, a kind of building structure prestressed concrete pipe pile Bearer properties test model and method.

Background technology

The horizontal bearing characteristic research of prestressed concrete pipe pile mainly include pile tube single pile horizontal bearing characteristic research, The horizontal bearing characteristic research of a pile tube clump of piles and a pile tube clump of piles bear the horizontal bearing characteristic research under vertical uniform load q.By Belonging to underground engineering in pile foundation, uncertain factor is more, and the completion time of project by engineering, environmental factors, anthropic factor are tested in scene Impact, it is difficult to the comprehensively bearer properties of the analysis and research pile foundation of multi-state.Therefore present stage is for the research master of pile foundation The methods such as numerical computations to be depended on, theory analysis.But the methods such as numerical computations are affected by physical parameter and constitutive model Relatively big, therefore verity and the accuracy of result of calculation is difficult to judge, result differs greatly with engineering is actual sometimes.

Summary of the invention

It is an object of the invention to overcome above-mentioned the deficiencies in the prior art, it is provided that one can preferably control load on pile foundation The loading condition requirement of test, simulates the practical working situation of pile foundation more realistically, probes into pile tube single pile and a clump of piles horizontal lotus The assay device of bearer properties under load effect.

The technical solution used in the present invention is as follows:

Prestressed concrete pipe pile horizontal bearing attribute testing model, including a model groove, cushion cap and Model Pile, in institute The model groove stated be arranged over connected and that cushion cap is implemented vertical force vertical loading system, inner side be provided with and its even That connect and to cushion cap carrying out horizontal power horizontal addload system, the upper end of described Model Pile is embedded in cushion cap, and described Cushion cap and Model Pile be provided with monitoring device.

Described monitoring device is the amesdial being arranged on cushion cap and the foil gauge being arranged in Model Pile.

Described vertical loading system includes carrying hydraulic jack I, being arranged at the pressure transducer of jack I end and erect To reaction frame, described vertical reaction frame is movably arranged on the top of connected model groove, and carries the perpendicular of hydraulic jack I To the top being arranged on vertical reaction frame.

Described horizontal addload system includes carrying hydraulic jack II and being arranged at the pressure transducer II of jack end, Described load hydraulic jack II is horizontally arranged at the upper of connected model groove.

Described model groove includes multiple Plate Welding frame unit being bolted together, at described soldering frame Frame unit is embedded with safety glass, and described safety glass middle part is provided with the draining of a diameter of 40mm communicated with the external world Hole；

Described Model Pile is lucite pile tube, is pasted with resistance strain gage outside it.

The modeling method of prestressed concrete pipe pile horizontal bearing attribute testing model is as follows:

Step 1 uses the dimension relation that similar second theorem (Buckingham theorem) determines between prototype and test model；

Step 2, according to shape, load type, load and the displacement of object of study, uses equational analysis exporting prototype Similarity criterion with test model；

Step 3 determines the similarity coefficient of model；

The similarity coefficient that step 4 obtains according to step 3, design experiment model.

Model test similar Design detailed process described in step 1 is as follows:

If if a physical phenomenon is containing n physical quantity, (its dimension is the most solely for fundamental physical quantity wherein m Stand), then this n physical quantity is expressed as being (n-m) individual similarity criterion π₁、π₂、...、π_n-mBetween functional relationship；Fixed by this Reason, that is:

f₁=(π₁,π₂,…,π_n-m)=0 (formula 1)

In formula: π_nN-th physical quantity.

Formula (1) is similarity criterion relational expression or π relational expression, and in formula, π item is similarity criterion.

The effect of Buckingham theorem: for the most similar phenomenon, engrave similarity criterion when corresponding point and correspondence and all keep same Value, so its π relational expression should also be as being identical；Represent prototype and model respectively with subscript " p " and " m ", then π relational expression is divided It is not:

f₁=(π_1p,π_2p,…,π_(n-m)p)=0 (formula 2)

f₂=(π_1m,π_2m,…,π_(n-m)m)=0 (formula 3)

Wherein: π_1m=π_1p；π_2m=π_2p；；π_{(n-m) m}=π_{(n-m) p}(formula 4)

In formula: π_1mFirst physical quantity in model；

π_1pFirst physical quantity in prototype.

From formula (4), if the result of the test of certain phenomenon being arranged the nondimensional π relational expression shown in an accepted way of doing sth (1), then This relational expression just extends to all other phenomenons similar to it up；And during promoting, from formula (4), and Need not list relation equation (no matter whether the equation finds) real between each π item.

The derivation process of the similarity criterion of step 2 is as follows:

Institute of the present invention object of study is elastic long stake, and load type is horizontal static load, therefore sets according to static(al) likeness in form model Meter；And load and displacement the least, select beam on elastic foundation curve differential equation be basis, use equational analysis lead Go out similarity criterion, as follows:

$\mathrm{EI}\frac{d^{4}y}{{\mathrm{dZ}}^4}+b_p{p}_z=\mathrm{EI}\frac{d^{4}y}{{\mathrm{dZ}}^4}+b_p{\mathrm{mZy}}_z=0$ (formula 5)

In formula: E Young's module of pile (kN/m²)；

I pile body cross sectional moment of inertia (m⁴)；

b_pCalculating width (m) of stake；

M proportionality coefficient；

The Z pile body degree of depth (m)；

y_zPile body displacement (m)；

p_zThe intensity of pressure in-unit are.

Consider that physics and boundary condition are similar, and according to dimension principle of homogeneity, obtain affinity constant as follows: wherein the first phenomenon (i.e. the actual index of engineering) use " ' " represent；Second phenomenon (i.e. model test index) uses " " " represent:

$C_E=\frac{E^{\′}}{E^{\′\′}},C_I=\frac{I^{\′}}{I^{\′\′}}={C_L}^4,C_{b_p}=C_Z=C_L=\frac{L^{\′}}{L^{\′\′}},C_{y_z}=\frac{{y_z}^{\′}}{{y_z}^{\′\′}},C_m=\frac{m^{\′}}{m^{\′\′}}=1$ (formula 6)

In formula: C_EElastic modelling quantity affinity constant；

C_ICross sectional moment of inertia affinity constant；

Calculate width affinity constant；

C_ZPile body degree of depth affinity constant；

Pile body displacement affinity constant；

C_mProportionality coefficient affinity constant；

C_LGeometric similarity constant；

L geometric constant.

The differential equation is write out by different phenomenons:

$E^{\′}{I}^{\′}\frac{d^4{y}^{\′}}{{\mathrm{dZ}}^{\′4}}+{b_p}^{\′}{m}^{\′}{Z}^{\′}{y_z}^{\′}=0$ (formula 7)

$E^{\′\′}{I}^{\′\′}\frac{d^4{y}^{\′\′}}{{\mathrm{dZ}}^{\′\′4}}+{b_p}^{\′\′}{m}^{\′\′}{Z}^{\′\′}{y_z}^{\′\′}=0$ (formula 8)

Carry out similarly transformation, by " " " parameter use " ' " parameter replacement, formula (8) is substituted into by the relation of formula (2), wherein C_Z= C_L:

$C_E{C}_I\frac{C_L}{{C_L}^4}{E}^{\′}{I}^{\′}\frac{d^4{y}^{\′}}{{\mathrm{dZ}}^{\′4}}+{C_L}^2{C}_m{C}_{y_z}{b_p}^{\′}{m}^{\′}{Z}^{\′}{y_z}^{\′}=0$ (formula 9)

When making similarity transformation, in order to ensure the concordance of fundamental differential, each term coefficient must be equal to each other, it may be assumed that

$C_E{C}_I\frac{C_L}{{C_L}^4}={C_L}^2{C}_m{C}_{y_z}\⇒\frac{C_E}{C_L{C}_{y_z}}=1$ (formula 10)

Therefore similarity criterion formula (1) can be obtained:

(formula 11)

Many its evolutions of physical phenomenon are directly affected by initial state, and therefore the present invention sets model test is similar Timing, it is contemplated that the initial condition of test is similar, as described below:

For horizontal loading F₀And moment M₀Coefficient complete embedding stake:

${\left[\mathrm{EI}\frac{d^2{y}_z}{{\mathrm{dZ}}^2}\right]}_{Z=0}=M_0,{\left[\mathrm{EI}\frac{d^3{y}_z}{{\mathrm{dZ}}^3}\right]}_{Z=0}=F_0$ (formula 12)

Consider that initial condition is similar, in like manner can obtain:

$E^{\′}{I}^{\′}\frac{d^2{y_z}^{\′}}{{\mathrm{dZ}}^{\′2}}=M^{\′}$ (formula 13)

$C_E{C}_I{E}^{\′}{I}^{\′}\frac{C_{y_z}{d}^2{y_z}^{\′}}{{C_L}^2{\mathrm{dZ}}^{\′2}}=C_M{M}^{\′}$ (formula 14)

In like manner carry out obtaining as similarity transformation:

In formula: C_MBending affinity constant.

Therefore similarity criterion formula (2) can be obtained:

(formula 15)

$E^{\′}{I}^{\′}\frac{d^3{y_z}^{\′}}{{\mathrm{dZ}}^{\′3}}=F^{\′}$ (formula 16)

$C_E{C}_I{E}^{\′}{I}^{\′}\frac{C_{y_z}{d}^2{y_z}^{\′}}{{C_L}^3{\mathrm{dZ}}^{\′2}}=C_F{F}^{\′}$ (formula 17)

In like manner carry out obtaining as similarity transformation:

In formula: C_FLoad affinity constant.

Therefore similarity criterion formula (3) can be obtained:

(formula 18)

Model similarity coefficient described in step 3 determines that process is as follows:

According to experimental condition and content requirement, this model test similarity coefficient design load includes data below:

Geometric similarity constant: C_L=C_{L model}/C_{L is actual}=0.1；

Filling material affinity constant: C_E1=1

Model Pile elastic modelling quantity affinity constant is: C_E2=C_{E model}/C_{E is actual}=0.1；

Displacement affinity constant: C can be obtained by similarity criterion formula (1)_yz=1；

Moment of flexure affinity constant: C can be obtained by similarity criterion formula (2)_M=0.001；

Load affinity constant: C can be obtained by similarity criterion formula (3)_F=0.01。

Test model specific design described in step 4 is as follows:

Step 4-1 testing equipment, mainly includes loading system, model groove and monitoring system；

(1) mould Blanking cavity design

The shape of model groove, size is with the test requirements document of satisfied single, each operating mode of clump of piles model test as criterion；

According to geometric similarity constant: C_L=C_{L model}/C_{L is actual}=0.1 determines Model Pile size.

According to load affinity constant C_F=0.01 determines horizontal loading and vertical load in loading procedure.

According to moment of flexure affinity constant C_M=0.001 determines moment in reckoning prototype.

(2) loading system

Loading system includes vertical loading system and horizontal addload system, and wherein vertical loading system offer 50kN's is vertical Load, horizontal addload system provides the horizontal loading of 300kN.

(3) monitoring system

The range of amesdial is 50mm；

The range of resistance-type soil pressure cell is 0.6MPa；

Resistance strain plate uses BX120-5AA series foil gauge.

Step 4-2 model test material specifically includes that Model Pile, model filler and cushion cap material；

(1) Model Pile material and size determine

Model Pile material is fixed then really:

A, can simulate stake soil soft or hard difference；B, the roughness of stake Soil Interface can be simulated；

C, can process and testing element is set；D, selected materials price are low, draw materials conveniently；

E, the size energy test simulation piles with different footpath of selected materials, the control analysis of wall thickness；

The size of Model Pile determines criterion:

Model Pile size is determined according to geometric similarity ratio (1:10)；

(2) filling material Criterion of Selecting

A: the stress deformation rule of clump of piles structure can be reacted；

B: filling material affinity constant: C_E1=1；

(3) cushion cap material selection criterion

The compatible deformation characteristic of soil-pile-raft can be simulated.

Beneficial effects of the present invention is as follows:

This model can not only logarithm value calculate result accuracy verify, and easy and simple to handle, Modulatory character is high, Avoid the limitation of on-the-spot test.Test model of the present invention and method can not only carry out pile foundation list, clump of piles horizontal bearing spy The model test of property, and a working property when clump of piles bears vertical load and horizontal loading simultaneously can be studied.And this Bright model can Dismountable, reusable, also can simulate the various indoor such as seepage stability, grouting mechanism, stability of slope Model test.

In this model, similar Design parameter is derived by similar second theorem, with a high credibility, and derivation is rigorous, by several What normal known quantity such as similarity number and Model Pile elastic modelling quantity affinity constant derives other unknown affinity constants, it is possible to more real Determine the design load of its mechanics parameter such as load, moment of flexure of model test.The design of this model test is on the premise of numerical computations Complete, the size of model groove meet in process of the test on before stake soil affect distance, during test method design, each ginseng Number has the proportionate relationship corresponding with prototype, of a tightly knit structure.

Accompanying drawing explanation

Fig. 1 model groove axonometric chart

Fig. 2 is model test loading system profile.

Fig. 3 is model test monitoring system and Model Pile profile.

In figure: 1 model groove, 2 vertical reaction frames, 3 horizontal addload systems, 4 vertical loading systems, 5 pressure transducers, 6 hold Platform, 7 Model Pile, 8 sands, 9 amesdials, 10 soil pressure cells, 11 foil gauges.

Detailed description of the invention

The present invention is described in detail below in conjunction with the accompanying drawings:

As shown in Figure 1-Figure 3, prestressed concrete pipe pile horizontal bearing attribute testing model, including a model groove 1, institute It is provided with the cushion cap 6 for carrying Model Pile in the model groove 1 stated, and the upper end of Model Pile 7 is embedded in cushion cap 6；Model Pile 7 Lower end is embedded in sand 8；Described model groove 1 be arranged over one that be connected with vertical reaction frame 2 and real to cushion cap Execute the vertical loading system 4 of vertical force, inside model groove 1, be provided with connected and to cushion cap carrying out horizontal power horizontal addload System 3, and it is provided with monitoring device in described cushion cap 6, Model Pile 7 and loading system.

Monitoring device be arranged on cushion cap amesdial 9, the foil gauge 11 being arranged in Model Pile, be arranged at Model Pile Soil pressure cell 10 around.

Vertical loading system 4 includes that carrying hydraulic jack I, described load hydraulic jack I is mounted vertically on reaction frame, Described reaction frame is arranged on the top of cushion cap；And it is provided with pressure transducer 5I in jack I end；

Horizontal addload system 3 includes that carrying hydraulic jack II, described load hydraulic jack II is horizontally arranged at it even On the inwall of the model groove connect, and it is provided with pressure transducer 5II in jack II end.

Model groove 1 includes multiple steel plate framework unit linked together, and is embedded with tempering glass at described frame unit Glass；Described safety glass middle part is provided with the osculum communicated with the external world；Described Model Pile is lucite pile tube, Resistance strain gage 11 it is pasted with outside it.

According to similarity mechanics principle and prototype condition design, modeling with carry out model test.The present invention be based on Similar second theorem carries out the simulation of pile tube bearer properties model test.

One, model test similar Design:

1, similar second theorem (Buckingham theorem)

The present invention uses similar second theorem (Buckingham theorem) to determine the dimension relation between the test model of prototype.Similar Second theorem can be expressed as: if setting a physical phenomenon to contain n physical quantity, wherein has m for fundamental physical quantity (its dimension It is separate), then this n physical quantity can be expressed as being (n-m) individual similarity criterion π₁、π₂、...、π_n-mBetween function Relation.By this theorem, that is:

f₁=(π₁,π₂,…,π_n-m)=0 (formula 1)

In formula: π₁1st physical quantity, π₂2nd physical quantity, π_n-mN-th-m physical quantity, n, m are natural number.

Formula (1) is similarity criterion relational expression or π relational expression, and in formula, π item is similarity criterion.

The effect of Buckingham theorem: for the most similar phenomenon, engrave similarity criterion when corresponding point and correspondence and all keep same Value, so its π relational expression should also be as being identical.General subscript " p " and " m " represent prototype and model, then π relation respectively Formula is respectively as follows:

f₁=(π_1p,π_2p,…,π_(n-m)p)=0 (formula 2)

f₂=(π_1m,π_2m,…,π_(n-m)m)=0 (formula 3)

Wherein: π_1m=π_1p；π_2m=π_2p；π_{(n-m) m}=π_{(n-m) p}(formula 4)

In formula: π_1mFirst physical quantity in model；π_2mSecond physical quantity in model；π_{(n-m) m}In model n-th- M physical quantity；

π_1pFirst physical quantity in prototype；π_2pSecond physical quantity in prototype；π_{(n-m) p}N-th-m thing in prototype Reason amount；

f₁Functional relation 1；f₂Functional relation 2.

From formula (4), if the result of the test of certain phenomenon being arranged the nondimensional π relational expression shown in an accepted way of doing sth (1), then This relational expression just extends to all other phenomenons similar to it up.And during promoting, from formula (4), and Need not list relation equation (no matter whether the equation finds) real between each π item.

2, the derivation of similarity criterion

Institute of the present invention object of study is elastic long stake, and load type is horizontal static load, can be similar to modelling according to static(al)； And load and displacement the least, can be selected for beam on elastic foundation curve differential equation is basis, use equational analysis lead Going out similarity criterion, this method has the advantage that

The most vertebration, the most essential in energy reflecting phenomena physical law, therefore conclusion is reliable；

2. process procedures is analyzed clear and definite, the most error-prone；

The level that affects of the most each factor is clear and definite, is beneficial to infer, compare and check.

$\mathrm{EI}\frac{d^{4}y}{{\mathrm{dZ}}^4}+b_p{p}_z=\mathrm{EI}\frac{d^{4}y}{{\mathrm{dZ}}^4}+b_p{\mathrm{mZy}}_z=0$ (formula 5)

In formula: E Young's module of pile (kN/m²)；

I pile body cross sectional moment of inertia (m⁴)；

b_pCalculating width (m) of pile body；

M proportionality coefficient；

The Z pile body degree of depth (m)；

y_zPile body displacement (m)；

p_zThe intensity of pressure in unit are.

Consider that physics and boundary condition are similar, and according to dimension principle of homogeneity, affinity constant can be obtained as follows: wherein first is existing Use as (i.e. the actual index of engineering) " ' " represent；Second phenomenon (i.e. model test index) uses " " " represent:

$C_E=\frac{E^{\′}}{E^{\′\′}},C_I=\frac{I^{\′}}{I^{\′\′}}={C_L}^4,C_{b_p}=C_Z=C_L=\frac{L^{\′}}{L^{\′\′}},C_{y_z}=\frac{{y_z}^{\′}}{{y_z}^{\′\′}},C_m=\frac{m^{\′}}{m^{\′\′}}=1$ (formula 6)

In formula: C_EElastic modelling quantity affinity constant；E ' engineering actual elastic modulus；E ' ' model elastic modelling quantity；

C_ICross sectional moment of inertia affinity constant；I ' engineering actual cross-section the moment of inertia；I ' ' model cross sectional moment of inertia；

Calculate width affinity constant；The actual geometric constant of L ' engineering；L ' ' model geometric constant；

C_ZPile body degree of depth affinity constant；y_z' displacement of engineering actual pile body；y_z' ' displacement of model pile body；

Pile body displacement affinity constant；M ' engineering actual ratio coefficient；M ' ' model scale coefficient；

C_mProportionality coefficient affinity constant；

C_LGeometric similarity constant；

L geometric constant.

The differential equation is write out by different phenomenons:

$E^{\′}{I}^{\′}\frac{d^4{y}^{\′}}{{\mathrm{dZ}}^{\′4}}+{b_p}^{\′}{m}^{\′}{Z}^{\′}{y_z}^{\′}=0$ (formula 7)

$E^{\′\′}{I}^{\′\′}\frac{d^4{y}^{\′\′}}{{\mathrm{dZ}}^{\′\′4}}+{b_p}^{\′\′}{m}^{\′\′}{Z}^{\′\′}{y_z}^{\′\′}=0$ (formula 8)

b_p' the engineering developed width of pile body；b_p' ' model width of pile body；

The engineering actual grade of Z ' stake；The model depth of Z ' ' pile body；

Carry out similarly transformation, by " " " parameter use " ' " parameter replacement, formula (8) is substituted into by the relation of formula (2), wherein C_Z= C_L:

$C_E{C}_I\frac{C_L}{{C_L}^4}{E}^{\′}{I}^{\′}\frac{d^4{y}^{\′}}{{\mathrm{dZ}}^{\′4}}+{C_L}^2{C}_m{C}_{y_z}{b_p}^{\′}{m}^{\′}{Z}^{\′}{y_z}^{\′}=0$ (formula 9)

When making similarity transformation, in order to ensure the concordance of fundamental differential, each term coefficient must be equal to each other, it may be assumed that

$C_E{C}_I\frac{C_L}{{C_L}^4}={C_L}^2{C}_m{C}_{y_z}\⇒\frac{C_E}{C_L{C}_{y_z}}=1$ (formula 10)

Therefore similarity criterion formula (1) can be obtained:

(formula 11)

Many its evolutions of physical phenomenon are directly affected by initial state, and therefore the present invention sets model test is similar Timing, it is contemplated that the initial condition of test is similar, as described below:

For horizontal loading F₀And moment M₀Coefficient complete embedding stake:

${\left[\mathrm{EI}\frac{d^2{y}_z}{{\mathrm{dZ}}^2}\right]}_{Z=0}=M_0,{\left[\mathrm{EI}\frac{d^3{y}_z}{{\mathrm{dZ}}^3}\right]}_{Z=0}=F_0$ (formula 12)

Consider that initial condition is similar, in like manner can obtain:

$E^{\′}{I}^{\′}\frac{d^2{y_z}^{\′}}{{\mathrm{dZ}}^{\′2}}=M^{\′}$ (formula 13)

$C_E{C}_I{E}^{\′}{I}^{\′}\frac{C_{y_z}{d}^2{y_z}^{\′}}{{C_L}^2{\mathrm{dZ}}^{\′2}}=C_M{M}^{\′}$ (formula 14)

In like manner carry out obtaining as similarity transformation:

In formula: C_MBending affinity constant；

Therefore similarity criterion formula (2) can be obtained:

(formula 15)

$E^{\′}{I}^{\′}\frac{d^3{y_z}^{\′}}{{\mathrm{dZ}}^{\′3}}=F^{\′}$ (formula 16)

$C_E{C}_I{E}^{\′}{I}^{\′}\frac{C_{y_z}{d}^2{y_z}^{\′}}{{C_L}^3{\mathrm{dZ}}^{\′2}}=C_F{F}^{\′}$ (formula 17)

In like manner carry out obtaining as similarity transformation:

In formula: C_FLoad affinity constant；

M pile body theory moment of flexure；The actual moment of flexure of M ' pile body engineering；M ' ' pile body model moment of flexure；

F theory load；F ' engineering actual loading；F ' ' model test load；

Therefore similarity criterion formula (3) can be obtained:

(formula 18)

3, model similarity coefficient determines

According to experimental condition and content requirement, model test main similarity coefficient design load is as follows:

Geometric similarity constant: C_L=C_{L model}/C_{L is actual}=0.1；

Filling material affinity constant: C_E1=1

Model Pile elastic modelling quantity affinity constant is: C_E2=C_{E model}/C_{E is actual}=0.1；

Displacement affinity constant: C can be obtained by similarity criterion formula (1)_yz=1；

Moment of flexure affinity constant: C can be obtained by similarity criterion formula (2)_M=0.001；

Load affinity constant: C can be obtained by similarity criterion formula (3)_F=0.01。

Two, model test content design:

1, testing equipment

Testing equipment is mainly made up of loading system, model groove and monitoring system.

Loading system includes loading equipemtn and Loading Control System, and the system of monitoring includes monitoring element and data acquisition system System.

(1) mould Blanking cavity design

According to bulk testing requirement, model groove should meet list, the test requirements document of each operating mode of clump of piles model test.Consider The functional requirement of model groove and numerical computations determine single, clump of piles stress and stress distribution scope under horizontal loads is preliminary Determine version and the size of model groove；Numerical computations display single pile (taking D=100mm operating mode) is made at Limiting Level load Maximum effect scope under with is: load direction 16.25m, load vertical direction 5.6m, and a clump of piles (takes 2 × 3, pile spacing 3D, D= 60mm operating mode) maximum effect scope under Limiting Level load action is: load direction 22.4m, load vertical direction 13.6m。

Consider above-mentioned result of calculation, the test factor such as feasibility, test period, be designed with pin-connected panel mould be can be combined Type groove, is i.e. designed to two kinds of forms of size according to test dimensional requirement by model groove.According to geometric similarity ratio (1:10) chosen Can determine that model groove size, use (1.2m × 2.0m) model groove that a clump of piles for single pile He (1 × 2) form is tested；Use A clump of piles for (1 × 3), (2 × 2) and (2 × 3) form is tested by (2.0m × 2.4m) model groove.

Consider the many factors such as content of the test, operation, function, use for reference existing model test experience and choose irony frame Frame+tempering lucite formula model groove, model groove top be furnished with lifting and counterforce device, the design of reaction frame undertakes load and is 500kN, utilizes model groove sidewall to provide horizontal reacting force.This model groove is adapted to different size needs, loading form, filling property And the model test such as Contents for Monitoring, can fully meet model test demand.

Model groove a size of length of the present invention is 2m × 2.4m × 2m, and model groove is by counter force wall, sidewall, lucite Observation window surrounds, and model groove top is furnished with reaction frame, driving, and the design load that reaction frame can undertake is 500kN, the side of model groove Wall can be as counter force wall, it is provided that horizontal reacting force.Wherein lucite is accompanied with preformed hole, under the conditions of simulating different water cut Scale (model) test.This test model groove have can assembled, be readily transported, be easy to regulate the advantages such as physical dimension.

(2) loading system

Pressurized equipment includes oil pump, jack.Horizontal thrust is applied by hydraulic jack, jack range 20cm, the peak load that can be provided by is 300kN, coordinates pressure transducer to carry out the size of control load.

(3) monitoring system

The monitoring system used in test includes amesdial (range 50mm), resistance-type soil pressure cell 10(range 0.6MPa), resistance strain plate, pressure transducer.Sound state strain acquirement instrument is used to gather soil pressure and pile strain data, Pressure transducer is used to monitor in real time being further applied load and proofread.

2, test material is chosen

Model test material specifically includes that Model Pile, model filler and cushion cap material.

(1) Model Pile material and size determine

1) determination of Model Pile material

Sum up lot of domestic and foreign pile foundation model test and in some basic principles selecting material of body of a pile:

A, can preferably simulate stake soil soft or hard difference；B, can suitably simulate the roughness of a Soil Interface；

C, be prone to processing and testing element is set；D, selected materials affordable, draw materials conveniently；

E, selected materials dimensions alternative strong, the beneficially control of the factor such as test simulation piles with different footpath, wall thickness Analyze.

Sum up tested experience and found that: lucite tube can reflect the stress deformation of soil-pile-raft very well Characteristic, and material homogeneity is good, be prone to "one off" production, is a kind of ideal Model Pile substitution material, and lucite bullet Property modulus and pile tube actual elastic modular ratio be about 1:10, i.e. elastic modelling quantity affinity constant C_E=0.1, beneficially model test design And data analysis.Therefore model test selects lucite tube as Model Pile substitution material.

2) determination of Model Pile physical dimension

Model Pile size is determined according to geometric similarity ratio (1:10).Wherein, according to Theoretical Calculation and numerical computations, stake Effective working depth be about 15m(25D) in, consider the factor such as test requirements document and experimental condition, Model Pile underground length Can reduced scale be 1.5m.

(2) filling material is chosen

Implementing for ease of test and the stress deformation rule of quality control, preferably reaction clump of piles structure, model test is sieved , as model filling material, it is consistent with real material to take medium sand (mean diameter is 0.5～0.25mm), i.e. similarity coefficient is 1.

(3) cushion cap material selection

Limited by working place in dimension of platform and template, be difficult to when cushion cap pours vibrate.But Model Pile and concrete Materials variances is relatively big, and two kinds of persons are difficult to be closely connected in the case of the most fully vibrating, and can have a strong impact on clump of piles horizontal bearing capacity Compatible deformation with soil-pile-raft.Therefore, for preferably simulating the compatible deformation characteristic of soil-pile-raft, model test is selected Pour cushion cap with C50 self-compacting concrete, and 7 days intensity reaches C40 strength criterion.

3, operating condition of test design

According to research needs, it was divided into for three stages implemented this model test, it may be assumed that

1. the Adjustment Tests stage: test is flowed by this stage by D=60mm single pile and two kinds of operating modes of (1 × 2) form clump of piles The test key content such as journey, safeguard, loading scheme, monitoring system carries out debugging, optimizing, to instruct follow-up test；

2. horizontal addload experimental stage: pile tube list, a clump of piles are carried out multi-state horizontal addload test, operating condition of test such as table 1 Shown in；

3. horizontal addload and the complementary testing stage: the pile foundation level bearing power increase measure proposed is entered by model test Row feasibility checking (operation, method, material, form etc.) and effect analysis.

Table 1 model test operating condition design

D represents a diameter, S_aRepresent pile spacing.

4, load and Contents for Monitoring designs

(1) loading scheme design

This model test uses the continuous Loading Method of single cycle to carry out test and loads, and specifies according to " pile foundation engineering handbook ": every Level load is to estimate ultimate bearing capacity or the 1/12～1/10 of maximum finder charge, and every grade of discharging quantity is 2 times of loading capacity；Load Every grade maintains 20min, unloads every grade and maintains 10min, is all that interval 5min surveys reading once.It is discharged to during zero load maintain 30min, Survey every 10min and read once.According to theoretical calculation method, determine that loading classification is as shown in table 2.

Table 2 horizontal loading loads grade

Termination loading environment:

1. pile body fractures；

2. horizontal displacement is more than 30～40mm；

3. horizontal displacement reaches the horizontal displacement permissible value that design requires；

4. horizontal loading reaches design and wants maximizing.

The loading system of the present invention includes horizontal addload system and vertical loading system, and load is by pressure transducer control System.

(2) monitoring plan design

1) pile strain monitoring

According to the bending regularity of distribution, the laying mode of pile strain piece collection upper tightly lower sparse, every pile glues 20, note Resistance strain plate.

2) pile body displacement and soil around pile pressure monitoring

Use amesdial (range 50mm) monitoring displacement at pile top；Use stake week under soil pressure cell 10 level monitoring load action The distribution situation of soil body soil pressure.

3) horizontal loading controls and monitoring

Controlling horizontal addload value for strict, it is measured, controls by the measuring instrument using precision to be 2N, and by tight The coaxial transmission of the mechanical position assurance load of lattice.

Three tests prepare

1, the viscous note of pile strain sheet

(1) chip select: first, whether mildew, rust spot the most parallel with lens examination wire grid, measures each with digimer Foil gauge resistance value, selects resistance value difference foil gauge in ± 0.5 Ω for pasting.

(2) cleaning on measuring point surface processes: lucite tube-surface is the most smooth, can dip in acetone scouring by direct cotton ball Surface；Mark the coordinate line of strain gauge again in survey sheet position with marking pen.

(3) paster: foil gauge and binding post are made complete, after foil gauge is pasted to Model Pile according to measurement direction On coordinate line；Then use 502 glue it to be bondd with Model Pile, at upper cover layer of polyethylene plastic foil as interlayer, use hands Refer to that the length direction in strain gauge rolls, extrudate piece bubble and unnecessary glue, until strain gauge and Model Pile close adhesion Till.

(4) wiring: twin cable is welded with binding post, and number.

(5) damp-proof treatment: after foil gauge carefully connects the wire and insulation resistance reaches requirement, uses AB glue to strain gauge immediately Carry out damp-proof treatment.

(6) measuring point protection: pasting adhesive waterproof tape after using foamed glue to cover.

(7) wiring: for reducing the testing element impact on test data, all first horizontal laying of foil gauge survey line becomes to stake soil Concentrating after shape coverage is outer again and go between earthward, in lateral extent, serpentine wire mode taked by survey line.

2, Model Pile is buried underground

Model Pile performs in strict accordance with EXPERIMENTAL DESIGN scheme during burying underground.

(1) committed step that Model Pile is buried underground is exactly the horizontal range of Controlling model stake and ensures the vertical of pile body.Therefore, Test model strictly controls the locus of pile body by the way of being mechanically fixed, and uses horizon rule and line pendant accurately to adjust Whole.

(2) (every layer of 20cm), compacting are successively filled according to quality control requirement, it is ensured that each layer soil body compactness is close, makes Carry out large area sand 8 with homemade big hammer ram to tamp, then carry out the compacting of stake week with homemade little hammer ram, should prevent during compacting Stop loss wound model stake and survey line；Every two-layer is chosen measuring point at 3 (piles with different away from, based on loaded segment face) and is used core cutter method after banketing Carry out the mensuration of compactness, to control filled soils.

(3) soil pressure cell 10 uses the mode of anti-excavation to bury underground, and strictly controls the installation position (distance of soil pressure cell 10 Stake outward flange 5cm), it is ensured that soil pressure cell 10 stress surface is perpendicular to loading direction.After pressure cell has been buried underground, sand should be backfilled 8 and carry out the compacting of same way, to ensure that compactness is with the most identical.

3, the pouring of cushion cap (only clump of piles test needs)

After Model Pile has been buried underground, start pouring of cushion cap.Connection height according to test requirements document, Model Pile and cushion cap For 5cm, for the accuracy tested, flatten pile peripheral earth first with horizon rule, then set up template, in the middle of this process, The position of strict Control architecture and direction, it is ensured that pile body heart position wherein.The present invention uses C50 self-compacting concrete to pour and holds Platform, therefore the mix-design of concrete and stirring means are referred to as the committed step of this process.Concrete after stirring is wanted Carry out slump consistancy test, test base slab after waiting to meet the requirements, can be poured.

4, monitoring system is installed and connects

Model installs horizontal addload and displacement monitor according to design requirement after having filled.Strict control equipment is installed Position, it is ensured that the coaxial transmission of horizontal loading and effective reading of horizontal displacement.

After test model and monitoring device have been installed, pile strain and Monitoring on Earth Pressure element are connected with Acquisition Instrument, And install signal compensation apparatus and carry out system debug；After system debug success, i.e. it is ready for test and loads.

Four, test loads and data monitoring

(1) initial reading of record amesdial, and detect the service behaviour of monitoring system, monitoring element is balanced behaviour Make.

(2) apply two-stage horizontal loading and carry out prestrain, unload after holding load 10min, record load reading instrument and thousand points The initial reading of table.

(3) load requirement according to design carry out test loading and record test data；Slow loading is answered during loading, and conscientiously Observe pile body shifting situation.

Five, Data Processing Method and foundation

1, horizontal displacement at stake ground

In test model of the present invention, on test pile (cushion cap) ground, two amesdials installed above carry out Horizontal Displacement Measure, according to the rotational angle theta on stake top under formula (19) calculated level load action₀, then at ground, horizontal displacement can be by formula (20) in stake Or formula (21) calculates.

(formula 19)

X₀=X_On-L_On×sinθ₀(formula 20)

Or X₀=X_Under-L_Under×sinθ₀(formula 21)

In formula: θ₀The corner on stake top；

X₀Horizontal displacement at stake ground；

X_OnUpper amesdial is to the horizontal range of pile center's line；

X_UnderLower amesdial is to the horizontal range of pile center's line；

L_OnUpper amesdial is to the vertical distance at ground；

L_UnderLower amesdial is to the vertical distance at ground.

2, bending

Theoretical about deflection of beam deformation and stress analysis according to the mechanics of materials, curved suffered by the arbitrary cross-section of pile body Square can be calculated by formula (22).

$M=\frac{\mathrm{EI}\·({\mathrm{\ϵ}}_{+}-{\mathrm{\ϵ}}_{-})}{b_0}$ (formula 22)

In formula: b₀The spacing of tension and compression strain measuring point；

The moment of inertia of I stake cross section centering axle；

The flexural modulus of elasticity of E pile body, all uses each diameter Model Pile stake flexural modulus when carrying out moment of flexure data analysis Measured value；

ε₊,ε_-Respectively draw at two measuring points in each cross section, compressive strain value, i.e. foil gauge are surveyed and are read data.

3, soil pressure against piles

Obtain according to the calculating formula (23) that Dandong City three reaches single mode soil pressure cell 10 that test instrunment factory produced supporting Soil pressure against piles value.

P=a (X+b) (formula 23)

In formula: P soil pressure force value (kPa)；

The strain value of X earth pressure gauge；

A, b are respectively the design factor of earth pressure gauge.

Claims (4)

1. the modeling method of prestressed concrete pipe pile horizontal bearing attribute testing model, it is characterised in that described test model Including a model groove, in described model groove, it is provided with the cushion cap for carrying Model Pile, and the upper end of Model Pile is embedded into and holds In platform；Described model groove be arranged over one that be connected with reaction frame and to cushion cap implement vertical force vertically load system System, is provided with connected and to cushion cap carrying out horizontal power horizontal addload system inside model groove, and at described cushion cap, mould Type stake and loading system are provided with monitoring device；Described monitoring device be arranged on cushion cap amesdial, be arranged at model Foil gauge in stake, the soil pressure cell being arranged at around Model Pile；

Described modeling method comprises the steps:

Step 1 uses similar second theorem to the dimension relation determining between prototype and test model；

Dimension relation between described prototype and test model is as follows:

Represent prototype and model respectively with subscript " p " and " m ", then corresponding dimension is as follows:

f₁=(π_1p,π_2p,…,π_(n-m)p)=0 (formula 1)

f₂=(π_1m,π_2m,…,π_(n-m)m)=0 (formula 2)

Wherein: π_1m=π_1p；π_2m=π_2p；π_(n-m)m=π_(n-m)p(formula 3)

In formula: π_1mFirst physical quantity in model；π_2mSecond physical quantity in model；π_(n-m)mN-th-m thing in model Reason amount；

π_1pFirst physical quantity in prototype；π_2pSecond physical quantity in prototype；π_(n-m)pN-th-m physical quantity in prototype；

f₁Functional relation 1；f₂Functional relation 2；

Step 2, according to shape, load type, load and the displacement of Model Pile, uses equational analysis exporting prototype and test The similarity criterion of model；

Described Model Pile be shaped as elastic long stake, described load type is horizontal static load；Horizontal displacement is less than or equal to 40mm；Maximum load is less than or equal to 8000N；Selecting beam on elastic foundation curve differential equation is basis, uses equation analysis Method exporting prototype and the similarity criterion of test model are as follows:

Similarity criterion formula (1)

In formula, E Young's module of pile；E ' engineering actual elastic modulus； E " model elastic modelling quantity；L geometric constant；The actual geometric constant of L ' engineering；L " model geometric constant；y_zPile body becomes Position；y_zThe actual pile body of ' engineering conjugates；y_z" model pile body conjugates；

Similarity criterion formula (2)

In formula, C_MBending affinity constant；C_EElastic modelling quantity affinity constant；C_LGeometric similarity constant；

Similarity criterion formula (3):

In formula, F theory load；F ' engineering actual loading；F " model test lotus Carry；E Young's module of pile；E ' engineering actual elastic modulus；E " model elastic modelling quantity；L geometric constant；L′— The actual geometric constant of engineering；L " model geometric constant；

Step 3 determines the affinity constant of model；

The affinity constant of described model is as follows:

Geometric similarity constant: C_L=C_{L model}/C_{L is actual}=0.1；

Filling material affinity constant: C_E1=1

Model Pile elastic modelling quantity affinity constant is: C_E=C_{E model}/C_{E is actual}=0.1；

Displacement affinity constant: C is obtained by similarity criterion formula (1)_yz=1；

Moment of flexure affinity constant: C is obtained by similarity criterion formula (2)_M=0.001；

Load affinity constant: C is obtained by similarity criterion formula (3)_F=0.01；

The affinity constant that step 4 obtains according to step 3, sets up test model；

The foundation of described test model includes testing equipment and test material:

Step 4-1 testing equipment, mainly includes loading system, model groove and monitoring device；

(1) mould Blanking cavity design

According to geometric similarity constant: C_L=C_{L model}/C_{L is actual}=0.1 determines Model Pile size；

According to load affinity constant C_F=0.01 determines horizontal loading and vertical load in loading procedure；

According to moment of flexure affinity constant C_M=0.001 determines moment in model；

(2) loading system

Loading system includes vertical loading system and horizontal addload system, and wherein vertical loading system provides the vertical lotus of 50kN Carrying, horizontal addload system provides the horizontal loading of 300kN；

(3) monitoring device

The range of amesdial is 50mm；

The range of resistance-type soil pressure cell is 0.6MPa；

Resistance strain plate uses BX120-5AA series foil gauge；

Step 4-2 model test material specifically includes that Model Pile, filling material and cushion cap material；

(1) Model Pile material and size determine

Model Pile material is fixed then really:

A, can simulate stake soil soft or hard difference；B, the roughness of stake Soil Interface can be simulated；

C, can process and testing element is set；D, selected materials price are low, draw materials conveniently；

E, the size energy test simulation piles with different footpath of selected materials, the control analysis of wall thickness；

The size of Model Pile determines criterion:

Model Pile size is determined than 1:10 according to geometric similarity；

(2) filling material Criterion of Selecting

A: the stress deformation rule of clump of piles structure can be reacted；

B: filling material affinity constant: C_E1=1；

(3) cushion cap material selection criterion

The compatible deformation characteristic of soil-pile-raft can be simulated.

2. the modeling method of prestressed concrete pipe pile horizontal bearing attribute testing model as claimed in claim 1, its feature It is: described vertical loading system includes that carrying hydraulic jack I, described load hydraulic jack I is mounted vertically in reaction frame On, described reaction frame is arranged on the top of cushion cap；And it is provided with pressure transducer I in jack I end.

3. the modeling method of prestressed concrete pipe pile horizontal bearing attribute testing model as claimed in claim 1, its feature It is: described horizontal addload system includes that carrying hydraulic jack II, described load hydraulic jack II is horizontally arranged at and it On the inwall of the model groove connected, and it is provided with pressure transducer II in jack II end.

4. the modeling method of prestressed concrete pipe pile horizontal bearing attribute testing model as claimed in claim 1, its feature It is: described model groove includes multiple steel plate framework unit linked together, and is embedded with tempering glass at described frame unit Glass；Described safety glass middle part is provided with the osculum communicated with the external world；Described Model Pile is lucite pile tube, Resistance strain gage it is pasted with outside it.