CN101046098B - Improved test method for vertical compression-resisting dead load test of single pile - Google Patents
Improved test method for vertical compression-resisting dead load test of single pile Download PDFInfo
- Publication number
- CN101046098B CN101046098B CN200710027692A CN200710027692A CN101046098B CN 101046098 B CN101046098 B CN 101046098B CN 200710027692 A CN200710027692 A CN 200710027692A CN 200710027692 A CN200710027692 A CN 200710027692A CN 101046098 B CN101046098 B CN 101046098B
- Authority
- CN
- China
- Prior art keywords
- pile
- test
- buttress
- equal
- load
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Images
Abstract
The improved test method for vertical compression-resisting dead load test of single pile has the improvements including principle of selecting datum point, principle of controlling the influence quantity of reverse load on trial pile draw-resisting load capacity, technological parameter requirement on displacement measurement instrument; determining the distances between datum pile, support pier,anchor pile and trial pile; monitoring datum pile, and determining the bearing force reducing coefficient. The present invention has reasonable control and elimination of the influence of reverse load on trial pile compression-resisting load capacity and jointing with ASTMD1143 standard in certain test conditions, and the improved test method is operable, practical, accurate and low in test cost.
Description
Technical field
The invention belongs to the Foundation Design field of construction work, be specifically related to the pile foundation detection field.
Background technology
The single pile vertical resistance pressure static loading test is mainly measured pile top load and two parameters of stake top displacement, according to pile top load, stake top displacement measurement analyzing evaluation single pile vertical resistance pressure bearing capacity.The single pile vertical resistance pressure static loading test can be selected ballast platform counterforce device, anchoring pile crossbeam counterforce device, anchor pole crossbeam counterforce device according to field condition.The single pile vertical resistance pressure static loading test mainly detects or tests according to standards such as JGJ106-2003, GB50007-2002, JTJ041-2000, ASTMD1143-81 at present, for eliminating or control the influence of counter-force load to the test pile test result, these standards have been made following regulation to loading counterforce device, displacement measurement system, displacement measuring instrument:
(1) ballast platform counterforce device
1. buttress foundation load level
GB50007-2002 regulation buttress foundation load should not surpass its characteristic load bearing capacity, JGJ106-2003 regulation buttress foundation load should not be greater than 1.5 times of its characteristic load bearing capacity, and ASTMD1143-81 regulation buttress has enough bearing areas to prevent the unfavorable sedimentation of ballast platform.
2. the distance between buttress and the test pile
The centre distance on JGJ106-2003, GB50007-2002 regulation test pile center and ballast platform buttress limit is more than or equal to 4d and greater than 2.0m, and d is the test pile intended diameter; The distance at JTJ 041-2000 regulation test pile center to ballast platform supports edge is more than or equal to 5d or 4m; The clear distance of ASTMD1143-81 regulation buttress and test pile is more than or equal to 1.5m.
3. the distance between reference pegs and buttress, the test pile
Centre distance between JGJ106-2003, the stake of GB50007-2002 stipulated standard and the test pile is more than or equal to 3-4d and greater than 2.0m, and the distance on reference pegs and ballast platform buttress limit is more than or equal to 4d and greater than 2.0m; JTJ 041-2000 stipulated standard pile center to the test pile center, the distance of ballast platform edges is more than or equal to 4d and more than or equal to 4m or 4m; ASTMD1143
[4]The clear distance of stipulated standard stake and test pile is more than or equal to 2.5m, and the distance of reference pegs and ballast platform buttress is far away as far as possible according to reality.
(2) anchoring pile crossbeam counterforce device
1. the distance between anchoring pile and the test pile
Centre distance between JGJ106-2003, GB50007-2002 regulation test pile and the anchoring pile is more than or equal to 3-4d and greater than 2.0m; JTJ041-2000 regulation anchoring pile and test pile center to center distance are more than or equal to 5d or 4m; The clear distance of ASTMD1143-81 regulation anchoring pile and test pile is more than or equal to 5d.
2. the distance between reference pegs and test pile, the anchoring pile
Centre distance between JGJ106-2003, the stake of GB50007-2002 stipulated standard and test pile, the anchoring pile is more than or equal to 3-4d and greater than 2.0m; The centre distance of stake of JTJ041-2000 stipulated standard and test pile, anchoring pile is more than or equal to 4d or 4m; The clear distance of stake of ASTMD1143-81 stipulated standard and test pile is more than or equal to 2.5m, and the distance of reference pegs and anchoring pile is far away as far as possible according to reality.
(3) displacement measuring instrument technical data
JGJ106-2003 regulation displacement measuring instrument should adopt displacement transducer or long range dial gage, and measure error is not more than 0.1%FS, and resolving power is better than or equals 0.01mm; JTJ041-2000 predetermined bits shift measurement adopts 1/20mm optical instrument or mechanics instrument; ASTMD1143-81 predetermined bits shift measurement meter accuracy 0.25mm, resolving power 0.25mm.
(4) along with the continuous increase in Pile Foundations Design load and stake footpath, the counter-force load becomes increasingly conspicuous to the influence of test pile resistance to compression bearing capacity and reference pegs displacement.Find that by analysis the single pile vertical resistance pressure Static Load Test Method that JGJ106-2003, GB50007-2002, JTJ041-2000, ASTMD1143-81 provide has the following disadvantages and defective:
1. lack the theoretical foundation of counter-force load to the influence of test pile resistance to compression bearing capacity.
2. lack counter-force load, test pile load experimental basis to reference pegs Influence of Displacement amount.
3. the regulation of the distance at ballast platform buttress limit and test pile center is not considered the influence of ballast platform buttress width.The distance on test pile center that domestic standard provides and ballast platform buttress limit causes the large diameter pile static loading test to be difficult to carry out the present situation of standard more than or equal to 4d and greater than the regulation of 2.0m.
4. the regulation of the distance between anchoring pile and the test pile does not wait from 3d-6d, has bigger difference.
5. the regulation of the distance between reference pegs and test pile, anchoring pile, the ballast platform buttress limit is not distinguished the difference of compressive pile, uplift pile, ballast platform buttress.
The restriction of the condition that 6. ought be put to the test, counter-force load when big, not have proposition to depart from the test method of clearance to the amount of influence of test pile resistance to compression bearing capacity.
7. large-scale loading test, especially ballast platform counterforce device, because reference point is difficult to avoid counter-force load perturbing area, the incorrect property of the instrument parameter of domestic regulation and stipulation causes the monitoring to the reference pegs displacement often to be difficult to carry out.
Summary of the invention
The objective of the invention is to control and eliminate reaction support surrounding soil subsidiary stress and the influence of distortion in the single pile vertical resistance pressure static loading test to test result, and provide a kind of retrofit testing method of single pile vertical resistance pressure static loading test, thereby improve the accuracy of measurement result.
For reaching above-mentioned purpose, the retrofit testing method of single pile vertical resistance pressure static loading test provided by the invention comprises following concrete test measure:
(1) determine the selection principle of reference point: choose counter-force load, test pile load to the ground deformation effect less than the foundation deformation point of 1mm as reference point;
(2) determine the control principle of counter-force load to the test pile resistance to compression supporting capacity amount of influence: the counter-force load to the amount of influence of test pile resistance to compression supporting capacity less than 5% maximum load amount;
(3) determine the technical data of displacement measuring instrument: it is 0.4mm that the minimum division value of displacement measuring instrument is not more than 1.0% of the critical displacement 40mm of compression test stake, and the error of indication is not more than ± 1.0%FS;
(4) determine distance between ballast platform buttress and the test pile: 1. under the compressive stress that ballast puts on the buttress ground satisfies 1.5 times condition smaller or equal to the buttress characteristic value of foundation bearing capacity, the clear distance of buttress and test pile is more than or equal to 1b and greater than 2m, and wherein b is the buttress width; 2. put under the satisfied condition smaller or equal to the buttress characteristic value of foundation bearing capacity of compressive stress of buttress ground at ballast, the clear distance of buttress and test pile is more than or equal to b/2 and greater than 1.5m;
(5) determine centre distance between anchoring pile and the test pile: 1. the centre distance of anchoring pile and test pile is more than or equal to 6d and greater than 2m, and wherein d is the diameter or the hem width of anchoring pile; 2. the centre distance of choosing anchoring pile and test pile is 3d-5d and greater than 2m, the bearing capacity that obtains under this condition need multiply by bearing capacity reducing coefficient;
(6) determine centre distance between anchor pole and the test pile: 1. to anchor pole crossbeam counterforce device, the centre distance of anchor pole and test pile is more than or equal to 6d and greater than 2m, and d is a bolt diameter; 2. to group's anchor crossbeam counterforce device, the centre distance of group's anchor and test pile is more than or equal to 6d and greater than 2m, and wherein d is the diameter or the hem width of group's anchor; 3. to group's anchor crossbeam counterforce device, the centre distance of choosing group anchor and test pile is 3d-5d and greater than 2m, the bearing capacity that obtains under this condition need multiply by bearing capacity reducing coefficient;
(7) determine distance between reference pegs and buttress, anchoring pile, anchor pole, the test pile: 1. under the compressive stress that ballast puts on the buttress ground satisfied 1.5 times condition smaller or equal to the buttress characteristic value of foundation bearing capacity, the distance on reference pegs and buttress limit was more than or equal to 1.5b and greater than 3m; 2. begin the measure tested after taking the buttress foundation settlement stable again, the distance on reference pegs and buttress limit is more than or equal to 1b and greater than 2m; 3. the centre distance of reference pegs and compressive pile is got more than or equal to 6m under the condition of d more than or equal to 1.5m more than or equal to 4d and greater than 2m; 4. the centre distance of reference pegs and uplift pile is got more than or equal to 6m under the condition of d more than or equal to 1.0m more than or equal to 6d and greater than 2m; 5. the centre distance of reference pegs and anchor pole is got more than or equal to 6m under the condition of group's anchor diameter d more than or equal to 1.0m more than or equal to 6d and greater than 2m; 6. in compressive pile stake footpath greater than 1.5m, uplift pile stake footpath greater than 1.0m, and the centre distance of reference pegs and compressive pile, uplift pile gets under the condition of 6m, determines whether to take monitoring measure to the reference pegs displacement according to actual conditions;
(8) determine the monitoring measure of reference pegs: 1. the displacement at reference pegs surpasses under the condition of 1mm, adopts second level displacement measurement system that the displacement of reference pegs is monitored; 2. first order displacement measurement system is measured the sedimentation of test pile with respect to reference pegs, and second level displacement measurement system measuring basis stake is with respect to the displacement of reference point; 3. datum line beam system, the displacement measurement instrument that second level displacement measurement system adopts and the first order is same measured, or the displacement measuring instrument that adopts resolution ratio to be better than 0.4mm is measured;
(9) determine bearing capacity reducing coefficient: to anchoring pile crossbeam counterforce device, group's anchor crossbeam counterforce device, be under the condition of 5d, 4d, 3d in the centre distance of anchoring pile, group's anchor and test pile, bearing capacity reducing coefficient gets 0.95,0.90,0.85 respectively.
The present invention also proposes, examination to engineering piles detects, maximum trial load conversion coefficient is got the inverse of bearing capacity reducing coefficient, its maximum trial load is got the ultimate load of designing requirement and the product of maximum trial load conversion coefficient, get at bearing capacity reducing coefficient under 1.0,0.95,0.90,0.85 the condition, maximum trial load conversion coefficient gets 1/1.0,1/0.95,1/0.90,1/0.85 respectively.
The present invention also proposes in addition, and single-pile static loading test carries out at the scene, need to determine the control criterion of displacement measurement errors: displacement measurement errors is less than 5% the total displacement of surveying.
The retrofit testing method of single pile vertical resistance pressure static loading test provided by the invention, be be based upon the stressed character analysis of single-pile vertical orientation static loading test stake soil, the counter-force load influences component analysis, counter-force load and test pile load to test pile resistance to compression bearing capacity and reference pegs is influenced on the basis of component analysis, below the invention will be further described:
One, test basis
The result of the test of compressive pile, uplift pile, anchor pole, the distortion of buttress surrounding soil, for control rationally and elimination counter-force buttress, counter-force stake surrounding soil are out of shape the influence to result of the test, the deformation test of the deformation test of the deformation test of 17 buttress surrounding soils, 16 compressive pile surrounding soils, 7 uplift pile surrounding soils, the deformation test of 8 anchor pole surrounding soils have been carried out.
(1) buttress surrounding soil deformation test
Totally 17 of three kinds of prototype tests that the buttress width is 0.7m, 1m, 2m have been carried out in the deformation test of buttress surrounding soil, and the distortion of the buttress surrounding soil that obtains with the pass of buttress distance is:
The buttress foundation load is during less than ultimate bearing capacity of foundation soil, buttress surrounding soil deflection: apart from buttress limit 1b and greater than 2m place foundation deformation in 2mm, b is the buttress width; Apart from buttress limit 1.5b and greater than 3m place foundation deformation in 1mm; Apart from buttress limit 2b and greater than 4m place foundation deformation in 0.5mm; The buttress foundation load is during greater than ultimate bearing capacity of foundation soil, and the ground deflection is bigger around the buttress, and possible sedimentation also may be swelled.
(2) compressive pile surrounding soil deformation test
Compressive pile surrounding soil deformation test has been carried out the stake footpath and has been totally 16 of four kinds of prototype tests of 400mm, 500mm, 1000mm, 1200mm, and the pile peripheral earth deformed region that obtains, the distortion of stake surrounding soil with the pass of pile center's distance are:
The deformation effect zone of the prefabricated compressive pile of the soil compaction formula face of land soil body, the deep soil body is 4d-7d, and d is stake footpath, apart from pile center greater than 4d after the deflection of pile peripheral earth less than 1mm.
The deformation effect zone of the castinplace pile face of land soil body is more than or equal to 4d, apart from pile center greater than 4d after the deflection of pile peripheral earth less than 1mm.
(3) deformation test of uplift pile surrounding soil
Uplift pile surrounding soil deformation test has been carried out the stake footpath and has been totally 7 of two kinds of prototype tests of 400mm, 500mm, the pile peripheral earth deformed region that obtains, stake surrounding soil distortion with the pass of pile center's distance are: the deformation effect zone of the uplift pile face of land soil body is 2d-6d, greater than the deflection of pile peripheral earth behind the 6d less than 1mm.
(4) deformation test of anchor pole surrounding soil
Totally 8 of the prototype tests that the aperture is 120mm have been carried out in the deformation test of anchor pole surrounding soil, and the distortion of the resistance to plucking anchor pole surrounding soil that obtains with the pass of anchor pole distance is:
The deformation effect zone of resistance to plucking anchor pole surrounding soil is more than or equal to 6d, and during more than or equal to 6d and greater than 2.0m, the distortion of soil layer is below 1mm around the anchor pole apart from the anchor pole distance.
Two, theoretical foundation
(1) rub according to the analysis of Slip Line Theory and the soil body and examine the angle reference value and calculate that the deformation failure zone of ground is 2b-9b around the buttress, b is the buttress width.
(2) ballast platform buttress load is to the influence of test pile resistance to compression bearing capacity
Ballast platform buttress load can be divided into the influence of the densification effect of buttress ground subsidiary stress, the distortion of buttress surrounding soil, buttress surrounding soil to test pile resistance to compression bearing capacity to the test influence on pile bearing capacity.Set up its calculation expression according to buttress ground subsidiary stress to the influence of test pile resistance to compression bearing capacity, to analyze of the influence of buttress ground subsidiary stress to test pile resistance to compression bearing capacity, analyze buttress foundation deformation and densification effect influence according to the distortion measured result of buttress ground surrounding soil to test pile resistance to compression bearing capacity, on this basis, determine distance between ballast platform buttress and the test pile.The concrete analysis result is:
The buttress foundation load is to the influence of test pile resistance to compression bearing capacity, be around the buttress ground densification effect cause the positive frictional resistance of test pile and ground subsidiary stress, buttress around the buttress on every side foundation deformation cause the result of the negative friction comprehensive function of test pile, restriction buttress foundation load or raising buttress bearing capacity of foundation soil are to reduce the key of buttress load to the influence of test pile bearing capacity, should control the buttress load in its ultimate bearing capacity of foundation soil.Its technical measures comprise to be handled the buttress ground, increases the buttress bearing capacity of foundation soil; Increase the buttress lifting surface area, reduce the buttress load.The compressive stress that puts on the buttress ground when ballast satisfies 1.5 times smaller or equal to the buttress characteristic value of foundation bearing capacity, the clear distance of buttress and test pile is more than or equal under 1b and the condition greater than 2m, b is the buttress width, the buttress foundation load to test influence on pile bearing capacity amount less than 5% maximum trial load; The compressive stress that puts on the buttress ground when ballast satisfies smaller or equal to the buttress characteristic value of foundation bearing capacity, the clear distance of buttress and test pile is more than or equal under b/2 and the condition greater than 1.5m, the buttress foundation load to test influence on pile bearing capacity amount less than 5% maximum trial load.
(3) the anchoring pile load is the influence of counter-force load to test pile resistance to compression bearing capacity
The anchoring pile load is to the influence of test pile resistance to compression bearing capacity: adopt the influence of elasticity analysis anchoring pile surrounding soil stress to test pile resistance to compression bearing capacity, and, set up the half theoretical semiempirical relation of anchoring pile load to the influence of test pile resistance to compression bearing capacity in conjunction with the existing achievement in research of the pile spacing in the efficiency of pile groups to the pile bearing capacity influence.
1. anchoring pile surrounding soil stress is to the influence of test pile stake resistance to compression bearing capacity: anchoring pile is separated and can simply be expressed as according to shear displacemant: Δ τ=τ the additional shear stress that the test pile surrounding soil produces
0r
0/ r.
Δ τ: the additional shear stress that anchoring pile produces the test pile surrounding soil,
τ
0: the shear stress of the test pile stake pedosphere face soil body,
r
0: the radius of test pile,
R: the distance on anchoring pile center and test pile limit.
When the center to center distance of test pile and counter-force stake is 6d, r=11r
0, be 9% to the amount of influence of test pile resistance to compression bearing capacity;
When the center to center distance of test pile and counter-force stake is 5d, r=9r
0, be 11% to the amount of influence of test pile resistance to compression bearing capacity;
When the center to center distance of test pile and counter-force stake is 4d, r=7r
0, be 14% to the amount of influence of test pile resistance to compression bearing capacity;
When the center to center distance of test pile and counter-force stake is 3d, r=5r
0, be 20% to the amount of influence of test pile resistance to compression bearing capacity.
2. analyze the influence of pile spacing to pile bearing capacity according to efficiency of pile groups: the stake-stake in the clump of piles interacts, and its stake is stressed in the same way, may cause enhancement effect or weaken effect; And the anchoring pile load is to the influence of test pile resistance to compression bearing capacity, anchoring pile is subjected to force direction opposite with test pile, but the subsidiary stress that anchoring pile produces its test pile surrounding soil, native stress, the distortion of distortion partial offset test pile stake week, this effect can be thought test pile resistance to compression bearing capacity is played advantageous effect, can improve the bearing capacity of test pile pile peripheral earth.This advantageous effect can determine that promptly the anchoring pile load is as follows to the increase rate of test pile resistance to compression bearing capacity with reference to efficiency of pile groups:
When the centre distance of anchoring pile and test pile is 6d, smaller or equal to 5% anchoring pile total load;
When the centre distance of anchoring pile and test pile is 5d, smaller or equal to 10% anchoring pile total load;
When the centre distance of anchoring pile and test pile is 4d, smaller or equal to 15% anchoring pile total load;
When the centre distance of anchoring pile and test pile is 3d, smaller or equal to 20% anchoring pile total load.
3. the anchoring pile load is to the analysis-by-synthesis of test pile bearing capacity influence
According to 1., 2. the counter-force pile load can comprehensively be generalized into table 1 to the analysis result of test pile bearing capacity influence.
Table 1 counter-force pile load is to the amount of the influence recommended value of test pile resistance to compression bearing capacity
The detailed description of retrofit testing measure:
(1) determine the selection principle of reference point: choose counter-force load, test pile load to the ground deformation effect less than the foundation deformation point of 1mm as reference point, based on the following: the measured result according to buttress, the distortion of stake surrounding soil is known, the influence basin of buttress foundation deformation is 2b-9b, the deformation effect scope of pile peripheral earth is more than 2d-7d, select fixed point as reference point, both unrealistic also uneconomical, choose foundation deformation point less than 1mm as reference point, can satisfy the requirement of single-pile vertical orientation static loading test.
(2) determine the control principle of counter-force load to the test pile resistance to compression supporting capacity amount of influence: the counter-force load to the amount of influence of test pile resistance to compression supporting capacity less than 5% maximum load amount, based on the following: the counter-force load is to test pile resistance to compression bearing capacity existence influence in various degree, especially there is the influence of certain degree in large-tonnage pile foundation compressive static load test counter-force load to test pile resistance to compression bearing capacity, to eliminate of the influence of counter-force load fully to test pile resistance to compression bearing capacity, both unrealistic, also with excessive increase testing cost; In addition, determine the single pile vertical resistance pressure bearing capacity by classification, as divide ten grades of loadings, then the analyzing evaluation error is near 10%; Therefore, suggestion counter-force load is as follows to the control principle of the test pile resistance to compression supporting capacity amount of influence: the counter-force load should be less than 5% maximum load amount to the amount of influence of test pile resistance to compression bearing capacity.
(3) determine the technical data of displacement measuring instrument: it is 0.4mm that the minimum division value of displacement measuring instrument is not more than 1.0% of the critical displacement 40mm of compression test stake, the error of indication is not more than ± 1.0%FS, based on the following: displacement measurement carries out at the scene, and the control criterion of displacement measurement errors can be taken as displacement measurement errors less than 5% the total displacement of surveying; For the degree of accuracy that makes measuring apparatus meets the demands, the allowable error that generally should make measuring apparatus is 1/3～1/10 of a measurand allowable error; When controlling the bearing capacity of stake by displacement simultaneously, the critical displacement of compressive pile is 40mm, therefore advise that displacement measuring instrument adopts following metering performance to require: the degree of accuracy should not be lower than 1.0 grades, minimum division value should not be 0.4mm greater than 1.0% of the critical displacement 40mm of compression test stake, and the error of indication should be ± 1.0%FS.
(4) determine distance between ballast platform buttress and the test pile: 1. under the compressive stress that ballast puts on the buttress ground satisfies 1.5 times condition smaller or equal to the buttress characteristic value of foundation bearing capacity, the clear distance of buttress and test pile is more than or equal to 1b and greater than 2m, and b is the buttress width; 2. put under the satisfied condition smaller or equal to the buttress characteristic value of foundation bearing capacity of compressive stress of buttress ground at ballast, the clear distance of buttress and test pile is more than or equal to b/2 and greater than 1.5m; Based on the following:
According to the buttress foundation load to the theoretical analysis result of test pile resistance to compression bearing capacity influence and definite counter-force load control principle to the test pile resistance to compression supporting capacity amount of influence: the counter-force load to the amount of influence of test pile resistance to compression supporting capacity less than 5% maximum load amount, distance between ballast platform buttress and the test pile can be defined as: the compressive stress that puts on the buttress ground when ballast satisfies 1.5 times smaller or equal to the buttress characteristic value of foundation bearing capacity, the clear distance of buttress and test pile is more than or equal to 1b and greater than 2m, and b is the buttress width; The compressive stress that puts on the buttress ground when ballast satisfies smaller or equal to the buttress characteristic value of foundation bearing capacity, and the clear distance of buttress and test pile is more than or equal to b/2 and greater than 1.5m; Technical measures: increase the buttress bearing capacity of foundation soil or increase the buttress loaded area.
(5) determine centre distance between anchoring pile and the test pile: 1. the centre distance of anchoring pile and test pile is more than or equal to 3d-6d and greater than 2m, and d is the diameter or the hem width of anchoring pile; 2. the condition restriction that ought be put to the test, the centre distance that can choose anchoring pile and test pile according to actual conditions are 3d-5d and greater than 2m, but the bearing capacity that obtains under this condition need multiply by bearing capacity reducing coefficient; Based on the following:
According to the anchoring pile load to the theoretical analysis result of test pile resistance to compression bearing capacity influence and definite counter-force load control principle to the test pile resistance to compression supporting capacity amount of influence: the counter-force load less than 5% maximum load amount, can be defined as the centre distance of anchoring pile and test pile 6d and greater than 2m to the amount of influence of test pile resistance to compression supporting capacity.The centre distance of anchoring pile and test pile is defined as the present situation of 3-4d in view of existing domestic standard JGJ106-2003, GB50007-2002, JTJ041-2000, and the girder steel in the measurement mechanism, datum line beam are subjected to the restriction of conditions such as traffic condition, on-the-spot installation, and the restriction of engineering piles spacing etc., the centre distance of anchoring pile and test pile also can be taken as 5d, 4d, 3d and greater than 2m; The counter-force pile load is respectively 5%, 10%, 15%, 20% maximum trial load to the increase rate of test pile vertical compression bearing capacity, and the bearing capacity of Huo Deing need multiply by bearing capacity reducing coefficient with this understanding.
(6) determine centre distance between anchor pole and the test pile: 1. to anchor pole crossbeam counterforce device, the centre distance of anchor pole and test pile greater than etc. 6d and greater than 2m, d is a bolt diameter; 2. to group's anchor crossbeam counterforce device, the centre distance of group's anchor and test pile greater than etc. 6d and greater than 2m, d is the diameter or the hem width of group anchor; 3. to group's anchor crossbeam counterforce device, when the condition restriction that is put to the test, the centre distance that can choose group anchor and test pile according to actual conditions is 3d-5d and greater than 2m, but the bearing capacity that obtains under this condition need multiply by bearing capacity reducing coefficient, and it is according to (5); When anchor pole spacing during, except that analyzing, still should consider by group's anchor by single anchor pole less than 10d or less than 1.0m.
(7) determine distance between reference pegs and buttress, anchoring pile, anchor pole, the test pile: when 1. the compressive stress that puts on the buttress ground when ballast satisfied smaller or equal to the buttress characteristic value of foundation bearing capacity 1.5 times, the distance on reference pegs and buttress limit was more than or equal to 1.5b and greater than 3m; During the measure that 2. after taking the buttress foundation settlement stable, begins again to test, the desirable 1b of distance on reference pegs and buttress limit and greater than 2m; 3. the centre distance of reference pegs and compressive pile is more than or equal to 4d and greater than 2m, when d desirable more than or equal to 6m during more than or equal to 1.5m; 4. the centre distance of reference pegs and uplift pile is more than or equal to 6d and greater than 2m, when d desirable more than or equal to 6m during more than or equal to 1.0m; 5. the centre distance of reference pegs and anchor pole is more than or equal to 6d and greater than 2m, when group's anchor diameter d desirable more than or equal to 6m during more than or equal to 1.0m.6. when compressive pile stake footpath greater than 1.5m, uplift pile stake footpath greater than 1.0m, and the centre distance of reference pegs and compressive pile, uplift pile is when getting 6m, should determine whether to take monitoring measure to the reference pegs displacement according to actual conditions; Based on the following:
According to the measured result of buttress, stake, anchor pole week soil deformation amount, the anchoring pile load of foundation, compression test pile load, anchor pole load are to reference pegs Influence of Displacement quantitative relationship:
1. the buttress foundation deformation is to the influence of reference pegs distortion, and the buttress foundation load is during less than the buttress ultimate bearing capacity of foundation soil, apart from buttress limit 1.5b and greater than the reference pegs displacement of 3m place in 1mm; The resilience of buttress ground is to the influence of reference pegs distortion, apart from buttress limit 1b and greater than the reference pegs displacement of 2m place in 0.5mm.When the measure taking the buttress ground to begin again behind the settlement stability under the effect of maximum preloading amount to detect, the distance on reference pegs and buttress limit is 1b and during more than or equal to 2m, the buttress foundation deformation to the influence of reference pegs displacement in 0.5mm.
2. reference pegs is from the centre distance of compression test stake during more than or equal to 4d, the compression test stake to the influence of foundation pile displacement less than 1mm.
3. reference pegs is from the centre distance of resistance to plucking test pile during more than or equal to 6d, the resistance to plucking test pile to the influence of foundation pile displacement less than 1mm.
4. reference pegs is from the distance of anchor pole during more than or equal to 6d and greater than 1.0m, anchor pole to the influence of foundation pile distortion less than 1mm; Reference pegs is from the distance of anchor pole during more than or equal to 6d and greater than 2.0m, anchor pole to the influence of foundation pile distortion less than 0.5mm.
5. reference pegs peels off the distance of anchor during more than or equal to 6d and greater than 2.0m, group's anchored loading to the influence of foundation pile distortion less than 1mm.
According to 1.-5. the result of the test and the selection principle of reference point, can determine the distance between reference pegs and buttress, anchoring pile, anchor pole, the test pile.Consider that shaped steel is generally 12m length, and the restriction of traffic condition, datum line beam should not be longer than 12m, when compressive pile stake footpath greater than 1.5m, uplift pile stake footpath greater than 1.0m, and when the centre distance of reference pegs and compressive pile, uplift pile is got 6m, should determine whether to take monitoring measure according to actual conditions to the reference pegs displacement.
(8) determine the monitoring measure of reference pegs: 1. the distortion when reference point surpasses under the condition of 1mm, adopts second level displacement measurement system that the displacement of reference pegs is monitored; 2. first order displacement measurement system is measured the sedimentation of test pile with respect to reference pegs, and second level displacement measurement system measuring basis stake is with respect to the displacement of fixed point; 3. second level displacement measurement system both can adopt the datum line beam system same with the first order, displacement measurement instrument to measure, and also the displacement measuring instrument that can adopt resolution ratio to be better than 0.4mm is measured; Based on the following:
Be subjected to the restriction of conditions such as traffic condition, on-the-spot installation in view of the girder steel in the measurement mechanism, datum line beam, reference point often is difficult to avoid buttress and test pile perturbing area, when counter-force load, test pile load surpass under the condition of 1mm the reference pegs deformation effect, suggestion adopts the method for monitoring criteria system variant to guarantee test pile displacement measurement result's accuracy; Concrete monitoring principle is as follows: displacement measurement can adopt the two-stage measuring system, first order displacement measurement system is measured the sedimentation of test pile with respect to reference pegs, second level displacement measurement system measuring basis stake is with respect to the displacement of fixed point, second level displacement measurement system both can adopt with same datum line beam system, the displacement measuring instrument of the first order and measure, and also the measuring instrument that can adopt accuracy of instrument 0.40mm, resolving power to be better than 0.40mm is measured.
(9) determine bearing capacity reducing coefficient: to anchoring pile crossbeam counterforce device, group's anchor crossbeam counterforce device, when the centre distance of anchoring pile, group's anchor and test pile is 5d, 4d, 3d, respectively less than 10%, 15%, 20% maximum load amount, bearing capacity reducing coefficient gets 0.95,0.90,0.85 respectively to the counter-force load to the test pile bearing capacity amount of influence; Based on the following:
The centre distance of anchoring pile and test pile is defined as the present situation of 3-4d in view of existing domestic standard JGJ106-2003, GB50007-2002, JTJ041-2000, and the girder steel in the measurement mechanism, datum line beam are subjected to the restriction of conditions such as traffic condition, on-the-spot installation, and the restriction of engineering piles spacing etc., cause the counter-force load test pile resistance to compression bearing capacity amount of influence to be surpassed the control principle of 5% maximum load amount; For taking into account the restriction of existing domestic standard present situation, traffic condition and field trial condition, the following clearance test measure that departs from is proposed, to guarantee the economy of precision of test result and testing cost.
Bearing capacity reducing coefficient: when the counter-force load to the test pile resistance to compression bearing capacity amount of influence during greater than 5% maximum load amount, the test pile resistance to compression bearing capacity that obtains with this understanding be multiply by one smaller or equal to 1 bearing capacity reducing coefficient, thereby obtain the true bearing capacity of test pile, to eliminate of the influence of counter-force load to test pile resistance to compression bearing capacity.
Specific practice is: when the reaction support load is 5%, 10%, 15%, 20% maximum load amount to the test pile resistance to compression bearing capacity amount of influence, then bearing capacity reducing coefficient gets 1,0.95,0.90,0.85 respectively, to guarantee that the counter-force load is to the control principle of the test pile resistance to compression bearing capacity amount of influence less than 5% maximum load amount.
(10) determine maximum trial load conversion coefficient: the examination to engineering piles detects, maximum trial load conversion coefficient is got the inverse of bearing capacity reducing coefficient, its maximum trial load is got the ultimate load of designing requirement and the product of maximum trial load conversion coefficient, when bearing capacity reducing coefficient got 1.0,0.95,0.90,0.85, maximum trial load conversion coefficient got 1/1.0,1/0.95,1/0.90,1/0.85 respectively; Its foundation is with (9).
Compared with the prior art, the present invention has the following advantages:
(1) the counter-force load is controlled in the 5% maximum trial load the test pile resistance to compression supporting capacity amount of influence.
(2) the displacement measuring instrument metering performance requirement of Ti Chuing, the selection principle of improved reference point, the monitoring method of reference pegs make the displacement measurement method of on-the-spot single pile vertical resistance pressure static loading test have more operability and reasonability.
(3) notion of the bearing capacity reducing coefficient of Ti Chuing, the counter-force load should be less than 5% control principle to the test pile resistance to compression bearing capacity amount of influence, taken into account the restriction of present situation, traffic condition and the field trial condition of existing domestic standard, make large-tonnage single pile vertical compression static loading test have more operability, changed the part static loading test and be difficult to rationally eliminate the present situation of counter-force load the influence of test pile resistance to compression bearing capacity.
(4) can solve domestic standard is continued to use 60-70 age paxilla footpath about distance between test pile, counter-force buttress, the reference pegs incorrect regulation, under special experiment condition, integrate with ASTMD1143, when the distance between test pile and counter-force buttress, the anchoring pile does not satisfy standard test conditions, adopt the solution of bearing capacity reduction, have stronger engineering practicability.
(5) improve the accuracy that the single pile vertical resistance pressure static loading test is tested the result, reduced testing cost.
Description of drawings
Fig. 1 is that 5-70 stake ballast platform plane of the present invention is arranged schematic diagram
Fig. 2 is that 5-18 stake ballast platform plane of the present invention is arranged schematic diagram
Fig. 3 is No. 1 piled anchor bar of an examination of the present invention crossbeam counterforce device layout schematic diagram
Fig. 4 is an examination CA11 piled anchor stake crossbeam counterforce device layout schematic diagram of the present invention
The specific embodiment
The present invention will be described to enumerate a part of specific embodiment below, is necessary to be pointed out that at this following specific embodiment only is used for that the invention will be further described, does not represent limiting the scope of the invention.Some nonessential modifications that other people make according to the present invention and adjustment still belong to protection scope of the present invention.
Embodiment 1
1 project profile
Fanyu District residential district, GuangZhou, Guangdong Province city, it is the bored pile of φ 1000-1200 that the stake footpath is adopted on the basis, designing pile length is 11～23 meters, bearing capacity of single pile design load φ 1000 is 5400kN, bearing capacity of single pile design load φ 1200 is 7700kN, must carry out single pile vertical resistance pressure bearing capacity static loading test, checking and accepting for pile foundation engineering provides foundation.
General condition of engineering geology: mainly by plain fill, chiltern cohesive soil, completely decomposed gneiss, severely-weathered gneiss, compositions such as middle weathering gneiss.
Present embodiment is with the bored pile of φ 1000, and the bearing capacity of single pile design load is that the single-pile static loading test of 5400kN is an example.The test pile No. is the 5-70 stake, the long 17.6m of stake.
2 testing schemes
Requiring the bearing capacity of single pile ultimate load is 8910kN, adopts ballast platform counterforce device, as shown in Figure 1.
(1) secondary beam: 450 * 600 * 11000,11, single beam evenly distributed load bearing capacity 2500kN.Girder adopts 500 * 1500 * 11000, two, single load bearing beam power 5000kN.Buttress adopts two buttresses of long 10m, wide 2m, and 2.6m is got to the distance at test pile center in the buttress limit.
(2) buttress foundation load level
The buttress ground through rubble change fill out processing after, the buttress characteristic value of foundation bearing capacity is 180kPa, maximum preloading amount is 8910 * 1.2=10692kN, then ballast puts on the compressive stress of buttress ground and is: 10692/20/2=267kPa, less than 1.5 times of buttress characteristic value of foundation bearing capacity, i.e. 180 * 1.5=270kPa.
(3) determine the distance of buttress limit to test pile
2.6m is got to the distance at test pile center in the buttress limit, and then buttress is 2.1m to the clear distance of test pile, satisfies more than or equal to 1b and greater than the requirement of 2m.
(4) installation of one-level baseline system
Datum line beam adopts the i iron of 12m, and two, the distance between the datum line beam is got 1.6m, and datum line beam is parallel to the girder direction; Reference pegs is parallel to the spacing of datum line beam length direction and gets 12m, gets 1.6m perpendicular to the spacing of datum line beam direction.
The distance at reference pegs and test pile center is 6m, satisfies more than or equal to 4d and greater than the requirement of 2m, d is test pile stake footpath, and the present embodiment stake directly is 1.0m.Reference pegs and ballast platform buttress limit apart from 2.06m, do not satisfy more than or equal to 1.5b and greater than the requirement of 3m, b buttress width 2m must carry out deformation monitoring to reference pegs.
(5) monitoring of reference pegs displacement
Can select for use displacement measuring instrument that resolving power is better than 0.4mm to reference pegs displacement monitor, this programme adopts secondary datum line beam system and dial gage to monitor.8 meters of secondary benchmark beam lengths adopt the mode of the 4m that encorbelments to install.The distance of the reference pegs of secondary datum line beam from the buttress limit is 5.64m, satisfies more than or equal to 1.5b and greater than the requirement of 3m.
(6) bearing capacity reducing coefficient or maximum trial load conversion coefficient determines
This routine bearing capacity reducing coefficient, maximum trial load conversion coefficient all get 1.0.
(7) add the off-load program: adopt the classification maintained load test (ML-test).
3 test results
(1) single pile load-displacement test result
Single pile load-displacement test result is as shown in table 2.
Table 2 5-70 pile load displacement measurement result
| Load (kN) | 1782 | 2763 | 3564 | 4455 | 5364 | 6237 | 7128 | 8019 | 8910 |
| Stake top sedimentation (mm) | 1.10 | 1.44 | 2.25 | 2.81 | 3.57 | 4.67 | 5.44 | 6.91 | 8.64 |
(2) reference pegs displacement monitoring result
The result is as shown in table 3 for the reference pegs displacement monitoring, and the datum line beam neutral displacement is got the average of reference pegs displacement.
Table 3 5-70 stake reference pegs displacement monitoring result
| Load (kN) | 1782 | 2763 | 3564 | 4455 | 5364 | 6237 | 7128 | 8019 | 8910 |
| Reference pegs displacement (mm) | 0.60 | 0.04 | -0.65 | -0.08 | -1.41 | -1.70 | -1.90 | -2.19 | -2.38 |
(3) sedimentation is revised on 5-70 stake pile top load-stake top
The stake top is revised sedimentation and is got the poor of a top sedimentation and reference pegs displacement, and it is as shown in table 4 that pile top load-sedimentation is revised on the stake top.
The sedimentation relation is revised on table 4 pile top load-stake top
| Load (kN) | 1782 | 2763 | 3564 | 4455 | 5364 | 6237 | 7128 | 8019 | 8910 |
| Sedimentation (mm) is revised on the stake top | 0.50 | 1.40 | 2.90 | 2.89 | 4.987 | 6.37 | 7.34 | 9.10 | 11.02 |
Test result: the 5-70 pile ultimate bearing capacity is more than or equal to 8910kN.Satisfy the acceptance requirement that the bearing capacity of single pile design load is 5400kN.
Embodiment 2
1 project profile
Fanyu District residential district, GuangZhou, Guangdong Province city, it is the bored pile of φ 1000-1200 that the stake footpath is adopted on the basis, designing pile length is 11～23 meters, bearing capacity of single pile design load φ 1000 is 5400kN, bearing capacity of single pile design load φ 1200 is 7700kN, must carry out foundation pile vertical compression bearing capacity static loading test, checking and accepting for pile foundation engineering provides foundation.
General condition of engineering geology: mainly by plain fill, chiltern cohesive soil, completely decomposed gneiss, severely-weathered gneiss, compositions such as middle weathering gneiss.
Present embodiment is with the bored pile of φ 1200, and the bearing capacity of single pile design load is that the single-pile static loading test of 7700kN is an example.The test pile No. is the 5-18 stake, the long 13.4m of stake.
2 testing schemes
Requiring the bearing capacity of single pile ultimate load is 12710kN, adopts ballast platform counterforce device, as shown in Figure 2.
(1) secondary beam: 450 * 600 * 11000,11, single beam evenly distributed load bearing capacity 2500kN.Girder adopts 500 * 1860 * 13000, two, single load bearing beam power 10000kN.Buttress adopts two buttresses of long 10m, wide 3m, and 2.6m is got to the distance at test pile center in the buttress limit.
(2) buttress foundation load level
The buttress characteristic value of foundation bearing capacity is 270kPa, and maximum preloading amount is 12710*1.2=15252kN, and then ballast puts on the compressive stress of buttress ground and is: 15252/30/2=254kPa, and less than buttress characteristic value of foundation bearing capacity 270kPa.
(3) determine the distance of buttress limit to test pile
2.6m is got to the distance at test pile center in the buttress limit, and then buttress is that 2.0m satisfies more than or equal to b/2 and greater than the requirement of 1.5m to the clear distance of test pile.
(4) installation of one-level baseline system
Datum line beam adopts the i iron of 12m, and two, the distance between the datum line beam is got 1.6m, and datum line beam is parallel to the direction of girder; Reference pegs is parallel to the spacing of datum line beam length direction and gets 12m, gets 1.6m perpendicular to the spacing of datum line beam direction.
The distance at reference pegs and test pile center is 6m, satisfies more than or equal to 4d and greater than the requirement of 2m, d is test pile stake footpath, and the present embodiment stake directly is 1.2m.Reference pegs and ballast platform buttress limit apart from 2.06m, do not satisfy more than or equal to 1.5b and greater than the requirement of 3m, b buttress width 2m must carry out deformation monitoring to reference pegs.
(5) monitoring of reference pegs displacement
Can select for use displacement measuring instrument that resolving power is better than 0.4mm to reference pegs displacement monitor, present embodiment adopts the accurate automatic compensated level of DSZ2 that the displacement of reference pegs is monitored, level gauge band parallel plate micrometer, resolving power 0.1mm estimates and reads to 0.01mm.
(6) bearing capacity reducing coefficient or maximum trial load conversion coefficient determines
This routine bearing capacity reducing coefficient, maximum trial load conversion coefficient all get 1.
(7) add the off-load program: adopt the classification maintained load test (ML-test).
3 test results
(1) single pile load-displacement test result
Single pile load-displacement test result is as shown in table 5.
Table 5 5-18 pile load displacement measurement result
| Load (kN) | 2542 | 3813 | 5084 | 6355 | 7626 | 8897 | 10168 | 11439 | 12710 |
| Stake top sedimentation (mm) | 0.51 | 0.82 | 1.30 | 1.63 | 2.20 | 2.67 | 3.33 | 4.11 | 4.90 |
(2) reference pegs displacement monitoring result
The result is as shown in table 6 for the reference pegs displacement monitoring, and the datum line beam neutral displacement is got the average of reference pegs displacement.
Table 6 5-18 stake reference pegs displacement monitoring result
| Load (kN) | 2542 | 3813 | 5084 | 6355 | 7626 | 8897 | 10168 | 11439 | 12710 |
| Reference pegs displacement (mm) | -0.04 | -0.06 | -0.09 | -0.09 | -0.11 | -0.13 | -0.13 | -0.16 | -0.16 |
(3) sedimentation is revised on 5-18 stake pile top load-stake top
The stake top is revised sedimentation and is got the poor of a top sedimentation and reference pegs displacement, and it is as shown in table 7 that pile top load-sedimentation is revised on the stake top.
The sedimentation relation is revised on table 7 pile top load-stake top
| Load (kN) | 2542 | 3813 | 5084 | 6355 | 7626 | 8897 | 10168 | 11439 | 12710 |
| Sedimentation (mm) is revised on the stake top | 0.55 | 0.88 | 1.39 | 1.72 | 2.32 | 2.80 | 3.46 | 4.27 | 5.06 |
Test result: the 5-18 pile ultimate bearing capacity is more than or equal to 12710kN.Satisfy the acceptance requirement that the bearing capacity of single pile design load is 7700kN.
Embodiment 3
1 project profile
It is the bored pile of φ 1200 that foreign capitals chemical plant, Zhuhai City, Guangdong Province engineering, basis intend adopting the stake footpath, for instructing Pile Foundations Design and construction, must carry out foundation pile vertical compression bearing capacity static loading test.Requiring this test pile quantity according to the consigner is 1, and trial load is 12000kN, and the test pile No. is No. 1 stake of examination.
Engineering geological conditions: the stratum of this engineering is as follows:
1. fill stratum: pale brown and brownish red, loose, mainly form by sand, wet, 5.9 meters of bed thickness;
2. weathering intercalated shale in the fragmentation: 0.4 meter of bed thickness;
3. completely decomposed shale: weathering becomes earthy strongly, 6.3 meters of buried depths, and mark passes through 11-19 and hits, and bed thickness is greater than 4 meters;
4. severely-weathered packsand: about 12 meters of buried depths, mark passes through 55 and hits about 6 meters of bed thickness;
5. middle weathered shale: about 12 meters of buried depths, 5.9 meters of bed thickness.
2 testing schemes
(1) trial load is 12000kN.Girder adopts 2 500 * 1860 * 13000 girder steels, every girder steel bearing capacity 10000kN, and secondary beam adopts 4 500 * 1500 * 11000 girder steels, every girder steel bearing capacity 5000kN.
(2) load counterforce device
Load counterforce device and adopt steel strand anchor pole crossbeam counterforce device, anchor pole adds up to 16, and wall scroll anchor pole design uplift resistance is 900KN, anchor pole aperture 130mm, and the anchor pole material adopts the steel strand of 7 φ 5, and the sectional area of steel strand is 961.6mm
2, steel strand strength standard value f
Prk=1470MPa, the anchor pole spacing is 1m * 1.2m.Anchor pole layout and anchor pole crossbeam counterforce device are as shown in Figure 3.
(3) centre distance of anchor pole and test pile is 6.84m, satisfies more than or equal to 6d and greater than the requirement of 2m, d is bolt diameter 130mm; The centre distance of group anchor and test pile is 7.8m, satisfies more than or equal to 6d and greater than the requirement of 2m, d is crowd anchor diameter 1.20m.
(4) distance of reference pegs and test pile, anchor pole
Datum line beam adopts the i iron of 12m, and two, the distance between the datum line beam is got 1.6m, and datum line beam is perpendicular to the girder direction; Reference pegs is parallel to the spacing of datum line beam length direction and gets 12m, gets 1.2m perpendicular to the spacing of datum line beam direction.
The centre distance of reference pegs and test pile is 6m, satisfies more than or equal to 4d and greater than the requirement of 2m; The distance of reference pegs and anchor pole is 4.2m, satisfies more than or equal to 6d and greater than the requirement of 2m.Reference pegs is 5.4m with the centre distance of group's anchor, does not satisfy more than or equal to 6d and greater than the requirement of 2m, must detect the reference pegs displacement.
(5) monitoring of reference pegs displacement
The displacement measuring instrument that can select for use resolving power to be better than 0.4mm is out of shape reference pegs monitors, and this programme adopts secondary datum line beam system and dial gage to detect.8 meters of secondary benchmark beam lengths adopt the mode of the 4m that encorbelments to install.The reference pegs of secondary datum line beam is 7.5m from a centre distance of group's anchor, satisfies more than or equal to 6d and greater than the requirement of 2m.
(6) add Uninstaller: adopt classification cycle to load the program of unloading.
Test adds, unloads: adopt the CYCLIC LOADING program, divide 4 circulations to add off-load.
The maximum trial load 3000kN of first circulation is by 0,1500kN, 3000kN add off-load.
Second circulation: maximum trial load 6000kN, by 0,3000kN, 4500kN, 6000kN add off-load.
The 3rd circulation: maximum trial load 9000kN, by 0,3000kN, 6000kN, 7500kN, 9000kN add off-load.
The 4th circulation: maximum trial load 12000kN, by 0,3000kN, 6000kN, 9000kN, 10500kN, 12000kN add off-load.
(7) bearing capacity reducing coefficient determines
Present embodiment bearing capacity reducing coefficient, maximum trial load conversion coefficient all get 1.
3 test results
First circulation: trial load 1500kN, total settlement is 0.55mm, and springback capacity is 0.33mm, and the residual settlement amount is 0.22mm.
Second circulation: during trial load 6000kN, total settlement is 3.03mm, and springback capacity is 2.15mm, and the residual settlement amount is 0.88mm.
The 3rd circulation: during trial load 9000kN, total settlement is 7.91mm.
The 4th circulation: during trial load 12000kN, total settlement is 10.09mm, and springback capacity is 5.40mm, and the residual settlement amount is 4.69mm.
This pile ultimate bearing capacity of analysis-by-synthesis is more than or equal to 12000kN.
Embodiment 4
1 project profile
Three eyot residential districts, Yunfu City, Guangdong Province, it is the bored pile of φ 1000-1400 that the stake footpath is adopted on the basis, designing pile length is 5～10 meters, bearing capacity of single pile design load φ 1000 is 4600kN, bearing capacity of single pile design load φ 1200 is 6300kN, and bearing capacity of single pile design load φ 1400 is 8100kN, must carry out foundation pile vertical compression bearing capacity static loading test, checking and accepting for pile foundation engineering provides foundation.
General condition of engineering geology: mainly by breaking up rock in gravelly clay, the white clouds matter, the little decomposed rock of white clouds matter.
Present embodiment is with the bored pile of φ 1200, and the bearing capacity of single pile design load is that the single-pile static loading test of 6300kN is an example.The test pile No. is the CA11 stake, the long 6.9m of stake.
2 testing schemes
2 testing schemes
(1) be 12600kN by the designing requirement ultimate load.Girder adopts 2 500 * 1860 * 13000 girder steels, every girder steel bearing capacity 10000kN, and secondary beam adopts 4 500 * 1500 * 11000 girder steels, every girder steel bearing capacity 5000kN.
(2) load counterforce device
Load counterforce device and adopt anchoring pile crossbeam counterforce device, anchoring pile adds up to 4 roots, and single stake anti-pulling capacity is 3500KN, anchoring pile stake footpath 1200mm, and the spacing of anchoring pile and test pile is 4.8m.Anchoring pile crossbeam counterforce device as shown in Figure 4.
(3) centre distance of anchoring pile and test pile is that 4d is 4.8m, does not satisfy more than or equal to 6d and greater than the requirement of 2m, d is anchoring pile diameter 1.2m; Must carry out reduction to bearing capacity.
(4) distance between reference pegs and test pile, the anchoring pile
Datum line beam adopts the i iron of 12m, and two, the distance between the datum line beam is got 1.6m, and reference pegs is parallel to the spacing of datum line beam length direction and gets 1.2m, gets 1.6m perpendicular to the spacing of datum line beam direction.The centre distance of reference pegs and test pile is 6m, satisfies more than or equal to 4d and greater than the requirement of 2m; The distance of reference pegs and anchoring pile is 4.92m, does not satisfy more than or equal to 6d and greater than the requirement of 2m, must detect the reference pegs displacement.
(5) monitoring of reference pegs displacement
Can select for use displacement measuring instrument that resolving power is better than 0.4mm to reference pegs displacement monitor, this programme adopts secondary datum line beam system and dial gage to detect.8 meters of secondary benchmark beam lengths adopt the mode of the 4m that encorbelments to install.The reference pegs of secondary datum line beam is 8.3m from a centre distance of group's anchor, satisfies more than or equal to 6d and greater than the requirement of 2m.
(6) add Uninstaller: adopt the classification maintained load test (ML-test).
(7) bearing capacity reducing coefficient determines
The centre distance of anchoring pile and test pile is 4d, and this routine bearing capacity reducing coefficient gets 0.90, and maximum trial load conversion coefficient gets 1/0.90.Maximum trial load is got 12600*1/0.90=14000kN.
(8) test result
Test result is as shown in table 8.
Table 8 5-18 pile load displacement measurement result
| Load (kN) | 2800 | 4200 | 5600 | 7000 | 8400 | 9800 | 11200 | 12600 | 14000 |
| Stake top sedimentation (mm) | 0.67 | 1.38 | 2.18 | 3.84 | 6.21 | 8.82 | 11.61 | 14.93 | 18.74 |
This pile ultimate bearing capacity is 1400*0.90=12600kN.Satisfy the acceptance requirement that the engineering piles characteristic load bearing capacity is 6300kN.
Claims (3)
1. the retrofit testing method of a single pile vertical resistance pressure static loading test is characterized in that comprising following concrete test measure:
(1) determine the selection principle of reference point: choose counter-force load, test pile load to the ground deformation effect less than the foundation deformation point of 1mm as reference point;
(2) determine the control principle of counter-force load to the test pile resistance to compression supporting capacity amount of influence: the counter-force load to the amount of influence of test pile resistance to compression supporting capacity less than 5% maximum load amount;
(3) determine the technical data of displacement measuring instrument: it is 0.4mm that the minimum division value of displacement measuring instrument is not more than 1.0% of the critical displacement 40mm of compression test stake, and the error of indication is not more than ± 1.0%FS;
(4) determine distance between ballast platform buttress and the test pile: 1. under the compressive stress that ballast puts on the buttress ground satisfies 1.5 times condition smaller or equal to the buttress characteristic value of foundation bearing capacity, the clear distance of buttress and test pile is more than or equal to 1b and greater than 2m, and wherein b is the buttress width; 2. put under the satisfied condition smaller or equal to the buttress characteristic value of foundation bearing capacity of compressive stress of buttress ground at ballast, the clear distance of buttress and test pile is more than or equal to b/2 and greater than 1.5m;
(5) determine centre distance between anchoring pile and the test pile: 1. the centre distance of anchoring pile and test pile is more than or equal to 6d and greater than 2m, and wherein d is the diameter or the hem width of anchoring pile; 2. the centre distance of choosing anchoring pile and test pile is 3d-5d and greater than 2m, the bearing capacity that obtains under this condition need multiply by bearing capacity reducing coefficient;
(6) determine centre distance between anchor pole and the test pile: 1. to anchor pole crossbeam counterforce device, the centre distance of anchor pole and test pile is more than or equal to 6d and greater than 2m, and d is a bolt diameter; 2. to group's anchor crossbeam counterforce device, the centre distance of group's anchor and test pile is more than or equal to 6d and greater than 2m, and wherein d is the diameter or the hem width of group's anchor; 3. to group's anchor crossbeam counterforce device, the centre distance of choosing group anchor and test pile is 3d-5d and greater than 2m, the bearing capacity that obtains under this condition need multiply by bearing capacity reducing coefficient;
(7) determine distance between reference pegs and buttress, anchoring pile, anchor pole, the test pile: 1. under the compressive stress that ballast puts on the buttress ground satisfied 1.5 times condition smaller or equal to the buttress characteristic value of foundation bearing capacity, the distance on reference pegs and buttress limit was more than or equal to 1.5b and greater than 3m; 2. begin the measure tested after taking the buttress foundation settlement stable again, the distance on reference pegs and buttress limit is more than or equal to 1b and greater than 2m; 3. the centre distance of reference pegs and compressive pile is got more than or equal to 6m under the condition of d more than or equal to 1.5m more than or equal to 4d and greater than 2m; 4. the centre distance of reference pegs and uplift pile is got more than or equal to 6m under the condition of d more than or equal to 1.0m more than or equal to 6d and greater than 2m; 5. the centre distance of reference pegs and anchor pole is got more than or equal to 6m under the condition of group's anchor diameter d more than or equal to 1.0m more than or equal to 6d and greater than 2m; 6. in compressive pile stake footpath greater than 1.5m, uplift pile stake footpath greater than 1.0m, and the centre distance of reference pegs and compressive pile, uplift pile gets under the condition of 6m, determines whether to take monitoring measure to the reference pegs displacement according to actual conditions;
(8) determine the monitoring measure of reference pegs: 1. the displacement at reference pegs surpasses under the condition of 1mm, adopts second level displacement measurement system that the displacement of reference pegs is monitored; 2. first order displacement measurement system is measured the sedimentation of test pile with respect to reference pegs, and second level displacement measurement system measuring basis stake is with respect to the displacement of reference point; 3. datum line beam system, the displacement measurement instrument that second level displacement measurement system adopts and the first order is same measured, or the displacement measuring instrument that adopts resolution ratio to be better than 0.4mm is measured;
(9) determine bearing capacity reducing coefficient: to anchoring pile crossbeam counterforce device, group's anchor crossbeam counterforce device, be under the condition of 5d, 4d, 3d in the centre distance of anchoring pile, group's anchor and test pile, bearing capacity reducing coefficient gets 0.95,0.90,0.85 respectively.
2. the retrofit testing method of single pile vertical resistance pressure static loading test according to claim 1, it is characterized in that determining maximum trial load conversion coefficient: the examination to engineering piles detects, maximum trial load conversion coefficient is got the inverse of bearing capacity reducing coefficient, its maximum trial load is got the ultimate load of designing requirement and the product of maximum trial load conversion coefficient, get at bearing capacity reducing coefficient under 1.0,0.95,0.90,0.85 the condition, maximum trial load conversion coefficient gets 1/1.0,1/0.95,1/0.90,1/0.85 respectively.
3. the retrofit testing method of this single pile vertical resistance pressure static loading test according to claim 1 is characterized in that determining the control criterion of displacement measurement errors: displacement measurement errors is less than 5% the total displacement of surveying.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN200710027692A CN101046098B (en) | 2007-04-25 | 2007-04-25 | Improved test method for vertical compression-resisting dead load test of single pile |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN200710027692A CN101046098B (en) | 2007-04-25 | 2007-04-25 | Improved test method for vertical compression-resisting dead load test of single pile |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN101046098A CN101046098A (en) | 2007-10-03 |
| CN101046098B true CN101046098B (en) | 2010-05-19 |
Family
ID=38770990
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN200710027692A Expired - Fee Related CN101046098B (en) | 2007-04-25 | 2007-04-25 | Improved test method for vertical compression-resisting dead load test of single pile |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN101046098B (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103953041B (en) * | 2014-04-30 | 2016-07-06 | 王利华 | The method of the foundation pile bearing capacity of single pile that a kind of raising has been constructed |
| CN108716225A (en) * | 2018-05-02 | 2018-10-30 | 广东天信电力工程检测有限公司 | A kind of novel club-footed pile test device for multifunctional and method |
| CN110004998A (en) * | 2019-05-14 | 2019-07-12 | 中国五冶集团有限公司 | A kind of bored concrete pile test pile apparatus and its pile testing method |
| CN110185070A (en) * | 2019-05-17 | 2019-08-30 | 长安大学 | Oblique Steep Slope Bridge vertical bearing capacity correction factor and bearing capacity computation method |
| CN113982047B (en) * | 2021-11-22 | 2023-03-10 | 山东东汇工程检测鉴定有限公司 | Construction engineering detects with engineering foundation pile detects fixing device |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2323174A (en) * | 1997-03-14 | 1998-09-16 | Kvaerner Cementation Found Ltd | Automatic static load testing for piles |
| US6349590B1 (en) * | 1997-09-15 | 2002-02-26 | Yee Kong Wai | Method and apparatus for estimating load bearing capacity of piles |
| CN2635379Y (en) * | 2003-08-20 | 2004-08-25 | 李梦斐 | Book having loose leaf tag |
-
2007
- 2007-04-25 CN CN200710027692A patent/CN101046098B/en not_active Expired - Fee Related
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2323174A (en) * | 1997-03-14 | 1998-09-16 | Kvaerner Cementation Found Ltd | Automatic static load testing for piles |
| US6349590B1 (en) * | 1997-09-15 | 2002-02-26 | Yee Kong Wai | Method and apparatus for estimating load bearing capacity of piles |
| CN2635379Y (en) * | 2003-08-20 | 2004-08-25 | 李梦斐 | Book having loose leaf tag |
Non-Patent Citations (4)
| Title |
|---|
| 方卫东.基桩静载试验探讨.岩土工程界8 4.2005,8(4),36-37,41. |
| 方卫东.基桩静载试验探讨.岩土工程界8 4.2005,8(4),36-37,41. * |
| 郭超敏.桩基竖向抗压承载力试验方法探讨.广东建材 5.2006,(5),89-90. |
| 郭超敏.桩基竖向抗压承载力试验方法探讨.广东建材 5.2006,(5),89-90. * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN101046098A (en) | 2007-10-03 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN103149094B (en) | The measuring method of tensile creep of early-age concrete | |
| Yoo et al. | Performance of geogrid-encased stone columns in soft ground: full-scale load tests | |
| Jiang et al. | Field instrumentation and evaluation of modular-block MSE walls with secondary geogrid layers | |
| Jamsawang et al. | Field behaviour of stiffened deep cement mixing piles | |
| CN100560875C (en) | The retrofit testing method of single-pile vertical orientation resistance to plucking static loading test | |
| CN101046098B (en) | Improved test method for vertical compression-resisting dead load test of single pile | |
| Voottipruex et al. | Performances of SDCM and DCM walls under deep excavation in soft clay: Field tests and 3D simulations | |
| CN108716225A (en) | A kind of novel club-footed pile test device for multifunctional and method | |
| Chen et al. | Laboratory evaluation of geogrid base reinforcement and corresponding instrumentation program | |
| McAffee et al. | Performance of an induced trench installation | |
| Dudek | Pile group settlement analysis on the basis of Static Load Test | |
| Tai-shan et al. | Study on the disturbance and recompression settlement of soft soil induced by foundation pit excavation | |
| Hosseinpour et al. | Field-measured Poisson's ratio of geotextile-encased granular column | |
| LU et al. | Study on the disturbance and recompression settlement of soft soil induced by foundation pit excavation | |
| Xu et al. | Model test on vertical bearing capacity of X-section concrete pile raft foundation in silica sand | |
| McGuire et al. | Bench-scale test apparatus for modeling column-supported embankments | |
| Baguelin et al. | The Menard pressuremeter test and the behaviour of laterally loaded piles in sands | |
| Bednarski et al. | The monitoring of a substrate strengthened with concrete columns | |
| Zhu et al. | Test research on the behavior of composite foundations incorporating rigid and flexible piles | |
| Madhav et al. | Analysis and comparison of displacement granular pile anchors | |
| CN212129265U (en) | Pile end resistance testing device at variable cross section of composite pile of riser pipe | |
| Watts et al. | Large-scale laboratory assessment of geogrids to reinforce granular working platforms | |
| Yashima et al. | A new optical fibre sensor to assess the stability of geogrid-reinforced soil walls | |
| Ismael et al. | Lateral capacity of augered tower foundations in sand | |
| Wang et al. | Vertical and Lateral Bearing Capacity of FRP Composite Sheet Piles in Soft Soil |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C56 | Change in the name or address of the patentee | ||
| CP03 | Change of name, title or address |
Address after: 510500 No. 121 martyrs East Road, Guangzhou, Guangdong, Tianhe District Patentee after: Guangdong Construction Academy Group Plc Address before: 510500 martyrs East Road, Guangdong, Guangzhou No. 121 Patentee before: Guangdong Prov. Inst. of Building Science |
|
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20100519 Termination date: 20160425 |