CN108625410A - A kind of test method of pile side friction - Google Patents
A kind of test method of pile side friction Download PDFInfo
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- CN108625410A CN108625410A CN201810465036.5A CN201810465036A CN108625410A CN 108625410 A CN108625410 A CN 108625410A CN 201810465036 A CN201810465036 A CN 201810465036A CN 108625410 A CN108625410 A CN 108625410A
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- pile
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- load box
- side friction
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D33/00—Testing foundations or foundation structures
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Abstract
The invention discloses a kind of test method of pile side friction, method is：Step 1: the making of load box；Step 2: the placement of load box；Step 3: concrete pours；Step 4: stake top loads；Step 5: data acquire；Step 6: pile side friction calculates；Step 7: single soil layer measures；Step 8: single soil layer side friction calculates；Beneficial effects of the present invention：The present invention has more significant reasonability and superiority relative to traditional measurement method.It can really realize that the simplification of test method, the reduction of test job intensity, the expansion of detection range and the raising of detection efficiency, test result will more meet reality, more can guarantee the accurate, objective of test result.
Description
Technical field
The present invention relates to a kind of test method of frictional resistance, more particularly to a kind of test method of pile side friction.
Background technology
Currently, pile foundation is a kind of widely used base form.Stake is contacted with soil in side wall and end, due to
The interaction of variability and the stake soil of soil layer property, it is resolved that the complexity of its stress.The bearing capacity of stake includes side friction
With bottom bearing two parts, wherein side friction is an amount changed greatly.In existing related specifications, according to Pile Soil material
The principal elements such as characteristic and Pile Soil interfacial characteristics, pile constructing process propose the influence degree of pile side friction after induction and conclusion
For pile side friction in the case of soil layer and certain pile-type, there are one relatively-stationary value ranges for limiting value, can be according to assembly
It carries power and carries out indirection, but the mutual value difference of different specification is larger.And found in practice in engineering, with end
The concrete engineerings such as support conditions, stake Impact direction, the property for closing on soil layer, depth of soil layer condition is different, and side friction can also
There is very big variation.The complex random systems situation encountered during pile foundation construction is more and more, and cited soil nature classification has been in specification
It is unsatisfactory for Practical Project demand.In this regard, to ensure how construction quality, rational evaluation bearing capacity of pile foundation directly accurately determine stake
Side friction size becomes critical issue.
Determine that the direct test method of pile side friction mainly by burying reinforcing rib meter in different soil section, is read at present
Actual measurement strain data is taken, be then calculated pile body in each soil by the stress-strain relation and pile body size of various complexity
Layer cross section axle power, mutual difference are this soil layer pile side friction, and each layer side friction sum is as total
Pile side friction.Influence of this method firstly the need of consideration varying environment to reinforcing bar；Secondly, pile concrete and reinforcing bar are answered
Stress-strain relationship is extremely complex, it is difficult to accurate description.This method is caused often to use some empirical parameters when calculating in this way,
Accuracy and reliability may be reduced.Which requires in barbola work and position strain gauge very high simultaneously, and excessively
Rely on the survival rate of strain gauge, it is also necessary to be demarcated in advance to different reinforcing bars, complicated construction technique, cost is higher.
Invention content
It is provided the purpose of the present invention is to solve problems present in existing shaft resistance force test method
A kind of pile side friction test method.
The test method of pile side friction provided by the invention, method are as described below：
Step 1: the making of load box：
Two diameters are made using steel plate to be less than by the disk of pile diameter, respectively as upper bearing disc and lower bearing disc, so
Several rope meters are fixed on lower bearing disc afterwards, one of rope meter is located at lower bearing disc center, other anchor cables
Meter is evenly distributed on a concentric circles on the outside of lower bearing disc；A hanging ring is welded at upper pressure-bearing disk center, is used for
It hangs；Finally upper bearing disc is connected with lower bearing disc by six roots of sensation gear rack, each gear rack matches nut, and is held under in upper bearing disc
Lightweight protective cover is installed at platen both ends, and to ensure that rope meter is not influenced in the construction process by external condition, load box made
Cheng Zhong, it is ensured that the flatness of upper bearing disc and lower bearing disc, to ensure rope meter energy uniform stressed；
Step 2: the placement of load box：
After determining stake holes qualification, carried out with concrete at stake bottom it is levelling, with crane by lotus after the solidification of concrete leveling layer
It carries case and a bottom is put by hanging ring, check and ensure that load box is horizontal；After in load box, installation is complete, by steel reinforcement cage
It is put into pile body；The data line of rope meter and pile body reinforcing bar are bound together, drawn from stake top；
Step 3: concrete pours：
After the completion of determining above-mentioned steps one and step 2, pouring for pile concrete is carried out；
Step 4: stake top loads：
After pile concrete maintenance reaches associated specifications, stake top is carried out using maintained load test (ML-test) at a slow speed according to specification
Load, and test method and end condition are determined according to existing specification；
Step 5: data acquire：
The pressure size q that pile top load Q, displacement s and each rope meter are born is acquired in loading procedure respectivelyi, the unit of Q
For kN, qiUnit be kN, i=1-n, n be practical rope meter number；
Step 6: pile side friction calculates：Pile side friction Q is calculated by following formulasu：
Step 7: single soil layer measures：
When needing to certain single soil layer pile side friction QSu is mono-When being tested, stake can be perfused under the soil layer when interface
Stop, as the screed-coat in step 2, then repeats step 2 and step 3；When in step 3 concreting to the soil
Stop pouring when interface on layer, carries out levelling rear repetition Step 2: Step 3: step 4 and step 5；
Step 8: single soil layer side friction calculates：
The sum of load box reading and the difference of the sum of upper bound area load case reading are the soil layer in lower interface in step 7
Side friction, calculation formula are as follows：
For the sum of load box reading in lower interface；
For the sum of load box reading in lower interface.
The quantity of examined stake can be determined in the above method according to actual demand.Pile concrete described in the above method pours
Build, stake top load and data acquisition are the prior art provided in existing related specifications and method, therefore specific steps do not have
It is repeated.
Beneficial effects of the present invention：
1, the test method of pile side friction provided by the invention is to install load box by stake bottom, using in load box
Rope meter directly measure end resistance QbuWith pile body dead weight G two parts, the difference of pile top load and load box reading is then calculated,
Pile body side friction can be immediately arrived at.Without demarcating reinforcing bar, concrete etc. before test, also avoid pasting strain
The complicated characterization processes such as meter.No matter from definition, principle or measuring accuracy, reliability and operability etc., this hair
It is bright that there is more significant reasonability and superiority relative to traditional measurement method.
2, method provided by the invention is suitable for all kinds of bad grounds and soil mass property, can avoid because included in specification
The problem of can not determining pile side friction value range caused by soil mass property is not complete.The property of soil layer is closed on without consideration
Influence of the concrete engineerings condition difference such as matter, depth of soil layer to pile side friction result of calculation.It can really realize test method
Simplification, the reduction of test job intensity, the expansion of detection range and detection efficiency raising, test result will more meet reality
Border more can guarantee the accurate, objective of test result.
Description of the drawings
Fig. 1 is load box main structure diagram of the present invention.
Fig. 2 is the lower bearing disc overlooking structure diagram of load box of the present invention.
1, upper bearing disc 2, lower bearing disc 3, rope meter 4, hanging ring 5, gear rack
7, lightweight protective cover 8, concrete leveling layer 9, steel reinforcement cage 10, pile body 11, data line.
Specific implementation mode
Please refer to Fig.1 with shown in Fig. 2：
The test method of pile side friction provided by the invention, method are as described below：
Step 1: the making of load box：
Two diameters are made using steel plate to be less than by the disk of pile diameter, respectively as upper bearing disc 1 and lower bearing disc 2,
Then several rope meters 3 are fixed on lower bearing disc 2, one of rope meter 3 is located at 2 center of lower bearing disc, other
Rope meter 3 be evenly distributed on a concentric circles in the outside of lower bearing disc 2；Welding one is hung at 1 center of upper bearing disc
Ring 4, for lifting by crane；Finally upper bearing disc 1 and lower bearing disc 2 are connected by six roots of sensation gear rack 5, each gear rack 5 match nut, and
Upper bearing disc 1 and lower 2 both ends of bearing disc installation lightweight protective cover 7, to ensure rope meter 3 in the construction process not by extraneous item
Part influences, in load box manufacturing process, it is ensured that the flatness of upper bearing disc 1 and lower bearing disc 2, to ensure that rope meter 3 can be
Even stress；
Step 2: the placement of load box：
After determining stake holes qualification, carried out with concrete at stake bottom it is levelling, with crane by lotus after the solidification of concrete leveling layer 8
It carries case and a bottom is put by hanging ring 4, check and ensure that load box is horizontal；After in load box, installation is complete, by reinforcing bar
Cage 9 is put into pile body 10；Together by the binding of the reinforcing bar of the data line 11 of rope meter 3 and pile body 10, it is drawn from stake top；
Step 3: concrete pours：
After the completion of determining above-mentioned steps one and step 2, pouring for 10 concrete of pile body is carried out；
Step 4: stake top loads：
After 10 concrete curing of pile body reaches associated specifications, stake is carried out using maintained load test (ML-test) at a slow speed according to specification
Top load, and test method and end condition are determined according to existing specification；
Step 5: data acquire：
The pressure size q that pile top load Q, displacement s and each rope meter 3 are born is acquired in loading procedure respectivelyi, the unit of Q
For kN, qiUnit be kN, i=1-n, n be practical rope meter 3 number；
Step 6: pile side friction calculates：Pile side friction Q is calculated by following formulasu：
Step 7: single soil layer measures：
When needing to certain single soil layer pile side friction QSu is mono-When being tested, stake can be perfused under the soil layer when interface
Stop, as the screed-coat in step 2, then repeats step 2 and step 3；When in step 3 concreting to the soil
Stop pouring when interface on layer, carries out levelling rear repetition Step 2: Step 3: step 4 and step 5；
Step 8: single soil layer side friction calculates：
The sum of load box reading and the difference of the sum of upper bound area load case reading are the soil layer in lower interface in step 7
Side friction, calculation formula are as follows：
For the sum of load box reading in lower interface；
For the sum of load box reading in lower interface.
The quantity of examined stake can be determined in the above method according to actual demand.Pile concrete described in the above method pours
Build, stake top load and data acquisition are the prior art provided in existing related specifications and method, therefore specific steps do not have
It is repeated.
The detailed process of illustrated below evaluation method：
(1) project profile
For certain railway by stratum based on the grey matter silt of brownish red volcano, the stratum disclosed by churning driven is divided into volcano heap
Lamination and the silt, flour sand, thin dust etc. for rushing proluvial deposit.China is existing《Railway bridges and culverts ground and foundation design code》No
With the value range recommended value of volcano adobe, the pile side friction of silt.And the Railway Bridge Pile Foundation is largely used and is rubbed
Wipe stake.Test pile diameter 1000mm, long stake is respectively 30m, 45m and 50m.
(2) load box makes
Bearing disc is 25mm steel plates, diameter 900mm to load box up and down；Six rope meters 3 are shared, wherein
Center 1 is evenly distributed with 5 on the circle of concentric with bearing disc and a diameter of 600mm；Upper and lower bearing disc is same by bearing disc
Equally distributed 6 gear racks 5 connection on the circle of the heart and a diameter of 700mm；There is hanging ring 4 at 1 center of upper bearing disc, around load box
Equipped with lightweight protective cover 7.
(3) detection process
When 10 concreting of pile body is to designated position, stop casting concrete.It, will with crane after concrete initial set
Load box is called in stake, after installing load box, checks that load box is horizontal.After in load box, installation is complete, by reinforcing bar
Cage 9 is put into pile body 10.Load box data line 11 and pile body reinforcing bar are bound together, drawn from stake top.Casting concrete to stake top,
It is loaded using maintained load test (ML-test) at a slow speed after maintenance to design strength, classification load is maximum load amount or estimates ultimate bearing
The 1/20 of power, the wherein first order take 2 times of classification load.In loading procedure related data is acquired in strict accordance with code requirement.
(4) testing result
Pile side friction calculating is carried out according to detection data result after detection.Its detection data and result of calculation are as follows
Shown in table 1.
1 detection data of table and result of calculation
Claims (1)
1. a kind of test method of pile side friction, it is characterised in that：Its method is as described below：
Step 1: the making of load box：
Two diameters are made using steel plate to be less than by the disk of pile diameter, respectively as upper bearing disc and lower bearing disc, then will
Several rope meters are fixed on lower bearing disc, and one of rope meter is located at lower bearing disc center, and other rope meters are equal
On an even concentric circles being distributed on the outside of lower bearing disc；A hanging ring is welded at upper pressure-bearing disk center, for lifting by crane；Most
Upper bearing disc is connected with lower bearing disc by six roots of sensation gear rack afterwards, each gear rack matches nut, and in upper bearing disc and lower bearing disc
Lightweight protective cover is installed at both ends, to ensure that rope meter is not influenced in the construction process by external condition, in load box manufacturing process,
The flatness for ensureing upper bearing disc and lower bearing disc, to ensure rope meter energy uniform stressed；
Step 2: the placement of load box：
After determining stake holes qualification, carried out with concrete at stake bottom it is levelling, with crane by load box after the solidification of concrete leveling layer
It is put into a bottom by hanging ring, check and ensures that load box is horizontal；After in load box, installation is complete, steel reinforcement cage is put into
Pile body；The data line of rope meter and pile body reinforcing bar are bound together, drawn from stake top；
Step 3: concrete pours：
After the completion of determining above-mentioned steps one and step 2, pouring for pile concrete is carried out；
Step 4: stake top loads：
After pile concrete maintenance reaches associated specifications, stake top is carried out using maintained load test (ML-test) at a slow speed according to specification and is added
It carries, and test method and end condition is determined according to existing specification；
Step 5: data acquire：
The pressure size q that pile top load Q, displacement s and each rope meter are born is acquired in loading procedure respectivelyi, the unit of Q is kN, qi
Unit be kN, i=1-n, n be practical rope meter number；
Step 6: pile side friction calculates：Pile side friction Q is calculated by following formulasu：
Step 7: single soil layer measures：
When needing to certain single soil layer pile side friction QSu is mono-When being tested, stake can be perfused to stopping when interface under the soil layer,
As the screed-coat in step 2, step 2 and step 3 are then repeated；In step 3 in concreting to the soil layer
Stop pouring when interface, carries out levelling rear repetition Step 2: Step 3: step 4 and step 5；
Step 8: single soil layer side friction calculates：
The sum of load box reading and the difference of the sum of upper bound area load case reading are that the soil layer side is rubbed in lower interface in step 7
Resistance, calculation formula are as follows：
For the sum of load box reading in lower interface；
For the sum of load box reading in lower interface.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810465036.5A CN108625410B (en) | 2018-05-16 | 2018-05-16 | Method for testing pile side frictional resistance |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201810465036.5A CN108625410B (en) | 2018-05-16 | 2018-05-16 | Method for testing pile side frictional resistance |
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| CN108625410A true CN108625410A (en) | 2018-10-09 |
| CN108625410B CN108625410B (en) | 2020-04-10 |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109457740A (en) * | 2018-12-06 | 2019-03-12 | 宁波大学 | A Soil Interface frictional resistance, the measuring instrument of normal stress and pore water pressure and its assembling application method can be measured simultaneously |
| CN109826249A (en) * | 2019-03-07 | 2019-05-31 | 中铁大桥（南京）桥隧诊治有限公司 | A kind of measuring device and measuring method of pile foundation side friction |
| CN109932116A (en) * | 2019-02-25 | 2019-06-25 | 河海大学 | A kind of side friction and bottom bearing test macro and measurement method |
| CN110230329A (en) * | 2019-07-12 | 2019-09-13 | 吉林大学 | The pile side friction experimental rig and method of indoor simulation soil around pile stress |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102635132A (en) * | 2012-05-04 | 2012-08-15 | 上海交通大学 | Pile body friction resistance meter |
| CN202610847U (en) * | 2012-03-16 | 2012-12-19 | 东南大学 | Measuring device of pile soil negative friction |
-
2018
- 2018-05-16 CN CN201810465036.5A patent/CN108625410B/en active Active
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN202610847U (en) * | 2012-03-16 | 2012-12-19 | 东南大学 | Measuring device of pile soil negative friction |
| CN102635132A (en) * | 2012-05-04 | 2012-08-15 | 上海交通大学 | Pile body friction resistance meter |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109457740A (en) * | 2018-12-06 | 2019-03-12 | 宁波大学 | A Soil Interface frictional resistance, the measuring instrument of normal stress and pore water pressure and its assembling application method can be measured simultaneously |
| CN109457740B (en) * | 2018-12-06 | 2023-08-22 | 宁波大学 | Measuring instrument capable of simultaneously measuring pile soil interface friction force, normal stress and pore water pressure and assembling and using method thereof |
| CN109932116A (en) * | 2019-02-25 | 2019-06-25 | 河海大学 | A kind of side friction and bottom bearing test macro and measurement method |
| CN109826249A (en) * | 2019-03-07 | 2019-05-31 | 中铁大桥（南京）桥隧诊治有限公司 | A kind of measuring device and measuring method of pile foundation side friction |
| CN109826249B (en) * | 2019-03-07 | 2023-08-22 | 中铁大桥（南京）桥隧诊治有限公司 | Pile foundation side friction resistance measuring device and measuring method |
| CN110230329A (en) * | 2019-07-12 | 2019-09-13 | 吉林大学 | The pile side friction experimental rig and method of indoor simulation soil around pile stress |
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| CN108625410B (en) | 2020-04-10 |
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