CN111576502B - Device and method for testing internal force of PHC (prestressed high-strength concrete) pipe pile by using optical fiber - Google Patents

Device and method for testing internal force of PHC (prestressed high-strength concrete) pipe pile by using optical fiber Download PDF

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CN111576502B
CN111576502B CN202010468411.9A CN202010468411A CN111576502B CN 111576502 B CN111576502 B CN 111576502B CN 202010468411 A CN202010468411 A CN 202010468411A CN 111576502 B CN111576502 B CN 111576502B
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depth
pile
optical fiber
section
strain
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CN111576502A (en
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于永堂
郑建国
刘争宏
张龙
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Machinery Industry Survey Design And Research Institute Co ltd
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Machinery Industry Survey Design And Research Institute Co ltd
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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

Abstract

The invention discloses a device and a method for testing the internal force of a PHC (prestressed high-strength concrete) tubular pile by using optical fibers, wherein the device comprises an optical fiber structure and an optical fiber demodulator, the top of the PHC tubular pile is provided with a load loading mechanism, the optical fiber structure comprises an optical fiber implanted tube and optical fibers, the optical fiber implanted tube comprises a plurality of sections of PPR (polypropylene random) tubes which are sequentially connected, and two adjacent sections of PPR tubes are connected through a tube joint; the method comprises the following steps: firstly, pre-connecting an optical fiber implantation tube; secondly, laying optical fibers; thirdly, implanting and grouting optical fibers; fourthly, testing the strain value of the PHC pipe pile; fifthly, fitting the strain value of the PHC pipe pile; and sixthly, acquiring the internal force of the PHC pipe pile. The invention has reasonable design, has small influence on the construction of the PHC tubular pile and ensures that the internal force of the PHC tubular pile is accurately tested.

Description

Device and method for testing internal force of PHC (prestressed high-strength concrete) pipe pile by using optical fiber
Technical Field
The invention belongs to the technical field of internal force testing of PHC tubular piles, and particularly relates to a device and a method for testing the internal force of a PHC tubular pile by using optical fibers.
Background
The PHC tubular pile is produced industrially, professionally and standardizedly, has reliable pile body quality, convenient transportation and hoisting, quick pile splicing and high mechanized construction degree, and is widely applied to civil and industrial buildings in China. Due to the structure and the construction process of the PHC tubular pile, the internal force of the PHC tubular pile during bearing is tested with great difficulty. At present, the method for testing the internal force of the PHC tubular pile mainly comprises a steel bar metering method and a distributed optical fiber method, and the steel bar metering method has low survival rate due to the structure and the construction process of the PHC tubular pile. The distributed optical fiber method has the advantages of high sensitivity, strong anti-interference capability, small volume and strong durability, and can be used for testing the internal force of the PHC tubular pile. However, in the existing distributed optical fiber method, grooves are carved on the outer surface of the tubular pile, and the optical fiber is fixed in the grooves to test the internal force of the pile foundation, the optical fiber implantation construction is complicated, and the cross influence with the pile driving construction is serious during the construction. In order to facilitate the internal force test of the PHC tubular pile, a device and a method for testing the internal force of the PHC tubular pile by using optical fibers, which are reasonable in design, are absent at present, so that the optical fibers are convenient to implant, the influence on the construction of the PHC tubular pile is small, and the internal force test of the PHC tubular pile is ensured to be accurate.
Disclosure of Invention
The invention aims to solve the technical problem of providing a device and a method for testing the internal force of the PHC tubular pile by using the optical fiber, aiming at the defects in the prior art, and the device and the method have the advantages of reasonable design, convenience in optical fiber implantation, small influence on the construction of the PHC tubular pile and capability of ensuring the accurate internal force test of the PHC tubular pile.
In order to solve the technical problems, the invention adopts the technical scheme that: the utility model provides an utilize device of optic fibre test PHC tubular pile internal force which characterized in that: comprises an optical fiber structure extending into the PHC tubular pile and an optical fiber demodulator connected with the optical fiber structure, the top of the PHC tubular pile is provided with a load loading mechanism, the optical fiber structure comprises an optical fiber implantation tube and optical fibers arranged on the optical fiber implantation tube, the optical fiber implantation tube comprises a plurality of sections of PPR tubes which are connected in sequence, two adjacent sections of PPR tubes are connected through tube joints, each tube joint is symmetrically provided with a first groove and a second groove, the lower part of the optical fiber implantation tube is symmetrically provided with a first lower groove, a second lower groove and an arc-shaped rotary groove for communicating the first lower groove and the second lower groove, the optical fibers comprise middle optical fibers arranged in the first lower groove, the arc-shaped rotary groove and the second lower groove in a penetrating mode, a first section of optical fibers arranged through the first groove and a second section of optical fibers arranged through the second groove, and the second section of optical fibers and the first section of optical fibers are symmetrically arranged along the PPR pipe;
the load loading mechanism comprises a jack and a counter force transmission component.
The device for testing the internal force of the PHC tubular pile by using the optical fiber is characterized in that: the marking lines on the PPR pipes are located on the same vertical line, and the projection of the first section of optical fiber on the PPR pipes and the marking lines on the PPR pipes are located on the same vertical line.
The device for testing the internal force of the PHC tubular pile by using the optical fiber is characterized in that: the center of the PPR pipe and the center of the PHC pipe pile are coaxially arranged, and the distance between the bottom of the optical fiber and the end plate at the bottom of the PHC pipe pile is 20-30 cm;
the grouting layer is filled between the PHC tubular pile and the PPR pipe, waterproof adhesive tapes are arranged on the first section of optical fiber and the second section of optical fiber at intervals of 30 cm-50 cm along the depth direction of the pile body, and the waterproof adhesive tapes are additionally arranged at the positions of the first groove and the second groove.
Meanwhile, the invention also discloses a method for testing the internal force of the PHC tubular pile by using the optical fiber, which has simple steps, reasonable design and convenient implementation, and is characterized by comprising the following steps:
step one, pre-connecting an optical fiber implantation tube:
101, connecting a plurality of sections of PPR pipes to form an optical fiber implantation pipe;
102, symmetrically forming a first groove and a second groove on each pipe joint by using an angle grinder;
103, forming an arc-shaped rotary groove, a first lower groove and a second lower groove on the lower part of the optical fiber implantation tube by using an angle grinder; the first lower groove, the arc-shaped rotary groove and the second lower groove are connected in sequence, the first lower groove and the second lower groove are symmetrically arranged, and the bottom of the arc-shaped rotary groove is higher than the bottom of the optical fiber implantation tube;
step two, optical fiber layout:
step 201, installing the middle part of an optical fiber to be laid into an arc-shaped rotary groove, bonding and fixing the optical fiber by using glue, and then winding the optical fiber and the optical fiber implantation tube by using a waterproof adhesive tape;
202, laying the optical fibers extending out of the arc-shaped rotary groove along the optical fiber implantation tube; the first section of optical fiber extending out of the arc-shaped rotary groove sequentially penetrates through the first lower groove and the first groove from bottom to top, the first section of optical fiber extending out of the arc-shaped rotary groove is arranged along the marking line on the PPR pipe, the second section of optical fiber extending out of the arc-shaped rotary groove sequentially penetrates through the second lower groove and the second groove from bottom to top, and the second section of optical fiber extending out of the arc-shaped rotary groove and the first section of optical fiber extending out of the arc-shaped rotary groove are symmetrically arranged along the PPR pipe;
step three, implanting and grouting the optical fiber:
301, installing the optical fiber implantation tube into the PHC tubular pile; the PHC tubular pile comprises a plurality of PHC tubular pile sections which are sequentially arranged from bottom to top, and the top of the PHC tubular pile is positioned at a designed pile top elevation value;
step 302, connecting a light-transmitting pen with the extending end of the optical fiber through an optical fiber jumper to judge that the optical fiber is normal;
step 303, injecting slurry between the PHC tubular pile and the PPR tube from bottom to top by using a slurry injection pump through a slurry injection tube to obtain a slurry injection layer;
step four, testing the strain value of the PHC tubular pile:
step 401, operating a load loading mechanism to apply load to the PHC tubular pile, and detecting strain values corresponding to the depths of all pile bodies through an optical fiber demodulator; wherein, the extending end of the optical fiber is connected with the optical fiber demodulator;
step 402, repeating the step 401 for multiple times, and applying multiple loads to the PHC tubular pile to obtain strain values corresponding to the depths of pile bodies when the loads are applied;
step 403, in the process that no load is applied to the PHC tubular pile, sending a plurality of groups of strain initial values detected by the optical fiber demodulator to a data processor; the data processor records the depth of the pile body smaller than the design value of the breakpoint of the depth of the pile body as the depth of the upper pile body, and the depth of the ith upper pile body in the depth of the plurality of upper pile bodies
Figure GDA0002881567760000031
The corresponding strain initial value is recorded as the ith upper pile body depth
Figure GDA0002881567760000032
Corresponding first strain initial value
Figure GDA0002881567760000033
And ith upper shaft depth
Figure GDA0002881567760000034
Corresponding second strain initial value
Figure GDA0002881567760000035
Recording the depth of the pile body which is not less than the design value of the breakpoint depth of the pile body as the depth of the lower pile body by the data processor, and recording the depth of the ith' lower pile body in the depth of the lower pile bodies
Figure GDA0002881567760000041
The corresponding strain initial value is recorded as the depth of the first section of optical fiber at the ith' lower pile body
Figure GDA0002881567760000042
First initial value of strain at cross section
Figure GDA0002881567760000043
And the depth of the second section of optical fiber at the ith' lower shaft
Figure GDA0002881567760000044
Second initial value of strain at cross section
Figure GDA0002881567760000045
Wherein i and i' are positive integers; i is more than or equal to 1 and less than or equal to m, m is a positive integer not less than 6, m represents the total number of the depth strain values of the upper pile body, i 'is more than or equal to 1 and less than or equal to m', m 'is a positive integer not less than 6, and m' represents the total number of the depth strain values of the lower pile body;
404, in the process of applying the jth load to the PHC tubular pile, detecting multiple groups of strain values by using an optical fiber demodulator and sending the strain values to a data processor;
when the jth load is loaded, the depth of the pile body is smaller than the design value z of the breakpoint of the depth of the pile bodyd,sThen, any upper pile depth strain value detected by the optical fiber demodulator is recorded as the depth of the first section of optical fiber at the ith upper pile depth when the jth applied load is applied
Figure GDA0002881567760000046
First strain value measured at cross section
Figure GDA0002881567760000047
And the depth of the second section of optical fiber at the ith upper pile body under the jth applied load
Figure GDA00028815677600000419
Measured second strain value at cross section
Figure GDA0002881567760000048
J is a positive integer, j is more than or equal to 1 and less than or equal to M, M represents the total number of times of load loading, and M is a positive integer more than 1;
when the data processor is adopted, the depth of the pile body is not less than the design value z of the breakpoint depth of the pile body when the jth load is loadedd,sWhen it is, thenAny lower pile depth strain value detected by the optical fiber demodulator is recorded as the depth of the first section of optical fiber at the ith' lower pile depth when the jth applied load is taken
Figure GDA0002881567760000049
First strain value measured at cross section
Figure GDA00028815677600000410
And the depth of the second section of optical fiber at the ith' lower shaft under the jth applied load
Figure GDA00028815677600000411
Measured second strain value at cross section
Figure GDA00028815677600000412
Step five, fitting treatment of strain values of the PHC tubular pile:
step 501, adopting the data processor according to a formula
Figure GDA00028815677600000413
Obtaining the ith upper pile body depth under the jth applied load
Figure GDA00028815677600000414
Average value of measured strain at cross section
Figure GDA00028815677600000415
Using said data processor according to a formula
Figure GDA00028815677600000416
Obtaining the ith' lower pile depth under the jth applied load
Figure GDA00028815677600000417
Measured average value of strain of
Figure GDA00028815677600000418
Step 502, building with the data processorUpper depth strain value fitting polynomial
Figure GDA0002881567760000051
Wherein, akRepresenting a monomial upper coefficient when the degree of a monomial in the upper depth strain value fitting polynomial is K, wherein z represents the upper pile body depth independent variable, epsilon (z) represents the upper fitting strain, K and K are positive integers, K is more than or equal to 0 and less than or equal to K, and K represents the highest degree of the upper depth strain value fitting polynomial;
establishing a fitting polynomial of lower depth strain values using the data processor
Figure GDA0002881567760000052
Wherein, a'k′The lower coefficient of a monomial in the lower depth strain value fitting polynomial is represented when the degree of the monomial is K ', z ' represents the lower pile body depth independent variable, epsilon ' (z ') represents the lower fitting strain, K ' and K ' are positive integers, K ' is more than or equal to 0 and less than or equal to K ', and K ' represents the highest degree of the lower depth strain value fitting polynomial;
step 503, respectively taking the m upper pile body depths in the j-th load application as upper pile body depth independent variables by adopting the data processor, and establishing an independent variable upper pile body depth matrix
Figure GDA0002881567760000053
Respectively taking the depth of m' lower pile bodies in the jth applied load as the depth independent variable of the lower pile bodies, and establishing an independent variable lower pile body depth matrix
Figure GDA0002881567760000054
Step 504, the data processor is adopted to respectively take the m measured strain average values corresponding to the m upper pile body depths during the jth applied load as upper strain values, and an upper strain value matrix is established
Figure GDA0002881567760000061
Recording the upper coefficient of each monomial in the upper depth strain value fitting polynomial as an upper coefficient matrix A＝[a0 a1 a2 … ak … aK]T；
Respectively taking m 'measured strain average values corresponding to m' lower pile body depths during the jth load application as lower strain values by adopting the data processor, and establishing a lower strain value matrix
Figure GDA0002881567760000062
The lower coefficients of the respective monomial equations in the lower depth strain value fitting polynomial are recorded as a lower coefficient matrix a '═ a'0 a′1 a′2 … a′k′… a′K′]T；
Step 505, setting the length of the PHC tubular pile to be L, and setting the depth of the ith upper pile body in the jth load loading by adopting the data processor
Figure GDA0002881567760000063
At the position of
Figure GDA0002881567760000064
And is less than the design value z of the depth breakpoint of the pile bodyd,sThe depth of any one upper pile body is recorded as the depth constraint value of the upper pile body
Figure GDA0002881567760000065
And the depth constraint value of the upper pile body during the jth load loading
Figure GDA0002881567760000066
The average value of the corresponding measured strain is
Figure GDA0002881567760000067
Depth of ith' lower pile body at jth load loading
Figure GDA0002881567760000068
At the position of
Figure GDA0002881567760000069
And is not less than the depth of the pile bodyDesign value z of degree breakpointd,sRecording the depth of any lower pile body as the depth constraint value of the lower pile body
Figure GDA00028815677600000610
And the depth constraint value of the lower pile body during the jth load loading
Figure GDA00028815677600000614
The average value of the corresponding measured strain is
Figure GDA00028815677600000611
Step 506, establishing an upper strain value fitting model by using the data processor, as follows:
Figure GDA00028815677600000612
wherein epsilon (A) is an upper strain value objective function, min represents a minimum value, s.t. represents a constraint condition, | · tory2A 2-norm representing a matrix; i | · | purple wind2Which is expressed as a square of the square of,
Figure GDA00028815677600000613
representing the first derivative of the independent variable about the depth of the upper pile body;
establishing a lower strain value fitting model by using the data processor, wherein the lower strain value fitting model is as follows:
Figure GDA0002881567760000071
wherein ε '(A') is the lower strain value objective function,
Figure GDA0002881567760000072
representing the first derivative of the independent variable about the depth of the lower pile body;
establishing a design value z of a pile body depth breakpoint by adopting the data processord,sThe strain value at (a) is fitted to the model as follows:
Figure GDA0002881567760000073
wherein the content of the first and second substances,
Figure GDA0002881567760000074
representing the second derivative with respect to the upper shaft depth argument,
Figure GDA0002881567760000075
representing the second derivative, epsilon, of the argument of depth of the lower shaftdDesign value z for representing pile body depth breakpointd,sThe corresponding measured strain average value;
and 507, solving the formula (I), (II) and (III) by using the data processor by using a least square method to obtain an upper coefficient matrix A ═ a0 a1 a2 … ak … aK]TAnd a lower coefficient matrix a '═ a'0 a′1 a′2 … a′k′ … a′K′]TTo obtain a fitting polynomial of the strain value of the upper depth
Figure GDA0002881567760000076
And a polynomial fit to the lower depth strain value
Figure GDA0002881567760000077
Step 508, using the data processor to determine the ith upper shaft depth at the jth applied load
Figure GDA0002881567760000078
Fitting polynomial into upper depth strain value
Figure GDA0002881567760000079
Obtaining the ith upper pile body depth under the jth applied load
Figure GDA00028815677600000710
Strain fit value at cross section
Figure GDA00028815677600000711
Using the data processor to determine the ith lower shaft depth at the jth applied load
Figure GDA0002881567760000081
Fitting polynomial into lower depth strain value
Figure GDA0002881567760000082
Obtaining the ith' lower pile depth under the jth applied load
Figure GDA0002881567760000083
Strain fit value at cross section
Figure GDA0002881567760000084
Step six, acquiring the internal force of the PHC tubular pile:
step 601, setting a plurality of upper pile body depths
Figure GDA0002881567760000085
Strain fit value at cross section
Figure GDA0002881567760000086
And a plurality of lower shaft depths
Figure GDA0002881567760000087
Strain fit value at cross section
Figure GDA0002881567760000088
Sequencing according to the sequence of the depth of the pile body from small to large, and recording the p-th strain fitting value in the strain fitting values of the depth sections of the pile bodies as
Figure GDA0002881567760000089
Wherein p is a positive integer, and p is more than or equal to 1 and less than or equal to m + m', the pth strain fitting value
Figure GDA00028815677600000810
The depth of the corresponding pile body is recorded as the p-th pile body depthDegree zp；
Step 602, employing the data processor according to a formula
Figure GDA00028815677600000811
Obtaining the p-th pile body depth zpAxial force Q at the cross sectionp(ii) a Wherein E ispIndicating the p-th shaft depth zpModulus of elasticity, A, of pile body concrete at cross sectionpIndicating the p-th shaft depth zpThe cross section area of the pile body at the cross section;
step 603, using the data processor according to a formula
Figure GDA00028815677600000812
Obtaining the p-th pile body depth zpThe depth z of the p +1 th pile body at the sectionp+1Lateral resistance q at the cross sectionps(ii) a Wherein u represents the perimeter of the body of the PHC tubular pile, and lpIndicating the p-th shaft depth zpThe depth z of the p +1 th pile body at the sectionp+1Pile length at cross section, Qp+1Represents the p +1 th pile depth zp+1Axial force at the cross section.
The above method is characterized in that: in the step 101, two adjacent sections of PPR pipes are connected through pipe joints, and marking lines on the PPR pipes are positioned on the same vertical line;
in the step 102, a first groove and a second groove on each pipe joint are symmetrically distributed along the PPR pipe, and the projection of the first section of optical fiber on the PPR pipe and the marking line on each section of the PPR pipe are positioned on the same vertical line;
in step 103, the radius of the arc-shaped rotary groove is more than 20 times of the outer diameter of the optical fiber;
in the step 301, the center of the PPR pipe and the center of the PHC pipe pile are coaxially arranged, and the distance between the bottom of the optical fiber and the end plate at the bottom of the PHC pipe pile is 20-30 cm;
in the step 303, the slurry is formed by mixing cement, bentonite and water, and the weight ratio of each part is 1000: : 1000.
the value range of the length L of the PHC tubular pile in the step 505 is 30 m-40 m.
The above method is characterized in that: pile body depth breakpoint design value z in step 403d,sThe specific process of obtaining is as follows:
step 4031, in the process of applying a load to the PHC tubular pile for one time, a plurality of groups of strain values detected by the optical fiber demodulator are sent to the data processor, and the data processor obtains the ith pile body depth z' of the first section of optical fiberi″First strain value epsilon at cross sectioni″,1And the depth z 'of the ith' pile body of the second section of optical fiberi″Second strain value epsilon at cross sectioni″,2(ii) a Wherein i' is a positive integer;
4032, using the data processor according to a formula
Figure GDA0002881567760000091
Obtaining the ith 'depth z' of pile body in one time of applying loadi″Measured average value of strain of
Figure GDA0002881567760000092
Wherein the content of the first and second substances,
Figure GDA0002881567760000093
indicating the depth z 'of the first section of optical fiber at the ith' pile bodyi″A first initial value of strain at the cross-section,
Figure GDA0002881567760000094
indicates the depth z 'of the second segment of the optical fiber at the ith' pile bodyi″A second initial value of strain at the cross-section;
4033, using the data processor according to a formula
Figure GDA0002881567760000095
Obtaining the ith 'depth z' of pile bodyi″Axial force Q' at the cross sectioni″(ii) a Wherein, E ″)i′Indicates the ith "pile depth zi″Modulus of elasticity, A ″, of pile concrete at the cross sectioni′Indicates the ith "pile depth zi″The cross section area of the pile body at the cross section;
4034, using the data processor according to a formula
Figure GDA0002881567760000096
Obtaining the ith 'depth z' of pile bodyi″The depth z between the cross section and the i' +1 th pile bodyi″+1Inter-side drag q 'at cross section'i′s(ii) a Wherein l'i′Indicates the ith "pile depth zi″The depth z between the cross section and the i' +1 th pile bodyi″+1Pile length, Q 'at cross section'i′+1Indicates the ith' +1 pile depth zi″+1Axial force at the cross section;
4035, using the data processor to determine the ith 'depth z' of the pile body by taking the depth of the pile body as the abscissa and the lateral resistance as the ordinatei″The depth z between the cross section and the i' +1 th pile bodyi″+1Inter-side drag q 'at cross section'i′sDrawing and fitting to obtain a side resistance curve;
4036, acquiring a minimum value point and a maximum value point of the side resistance curve by using the data processor, recording a small pile depth corresponding to the minimum value point as a minimum pile depth, recording a small pile depth corresponding to the maximum value as a maximum pile depth, and averaging the minimum pile depth and the maximum pile depth to obtain a pile depth breakpoint design value zd,s。
The above method is characterized in that: the following steps are also carried out between the second step and the third step:
step 203, laying waterproof adhesive tapes along the first section of optical fiber extending out of the arc-shaped rotary groove and the second section of optical fiber extending out of the arc-shaped rotary groove at intervals of 30-50 cm along the depth direction of the pile body; waterproof adhesive tapes are additionally arranged at the first groove and the second groove;
and step 204, sleeving centralizers outside the two pipe joints to complete the arrangement of the optical fiber implantation pipes.
The above method is characterized in that: in step 401, before applying a load to the PHC tubular pile, a load loading mechanism needs to be set, which includes the following steps:
step A, arranging a pile cap above the PHC pipe pile, and penetrating an optical fiber from the pile cap;
b, PHC, arranging anchor piles at two sides of the tubular pile, and erecting a cross beam on the two anchor piles;
step C, arranging a middle beam at the bottom of the cross beam, and arranging a plurality of jacks between the pile caps and the middle beam;
d, connecting the extending end of the optical fiber with an optical fiber demodulator;
in step 401, the load loading mechanism is operated to apply a load to the PHC tubular pile, and the specific process is as follows: operating the jacks to extend, and applying load to the PHC tubular pile through the pile caps by the combined force of the jacks; wherein, the loading counter force of jack is transmitted to the anchor pile through centre sill and crossbeam.
Compared with the prior art, the invention has the following advantages:
1. simple structure, reasonable in design and simple and convenient, the input cost is lower in the installation.
2. The PPR pipe that adopts carries out laying of optic fibre to utilize the mark line on the PPR pipe, ensure to stretch out the first section optic fibre outside the arc-shaped rotary groove by supreme first recess that passes in proper order down, and stretch out the first section optic fibre edge outside the arc-shaped rotary groove the mark line on the PPR pipe is laid, and the second section optic fibre that stretches out outside the arc-shaped rotary groove passes the second recess by supreme down in proper order, and stretches out the second section optic fibre outside the arc-shaped rotary groove and stretch out the first section optic fibre of arc-shaped rotary groove and lay along PPR pipe symmetry, has improved the convenience of laying.
3. The optical fiber implanting tube is used for implanting optical fibers after the PHC tubular pile construction is completed, so that the cross influence of the PHC tubular pile construction is avoided, and the construction is convenient.
4. Slurry is filled between the adopted optical fiber implantation tube and the PHC tubular pile, and the deformation of the pile body of the PHC tubular pile can be well transferred to the optical fiber through the solidification of the slurry, so that the aim of testing the internal force of the pile body is fulfilled.
5. The optical fiber implanting pipe is used for realizing the laying and later-stage grouting of the optical fibers, all work can be completed at one time, the working efficiency is high, the high-temperature maintenance of the PHC pipe pile factory prefabrication is effectively avoided, and the quality of the optical fiber pre-implanted PHC pipe pile is influenced due to the complex manufacturing process.
6. The method for testing the internal force of the PHC tubular pile by using the optical fiber has the advantages of simple steps, convenience in implementation and simplicity and convenience in operation.
7. The method for testing the internal force of the PHC tubular pile by using the optical fibers is simple and convenient to operate and good in using effect, firstly, the optical fiber implantation pipes are pre-connected, secondly, the optical fibers are distributed, and the optical fibers are symmetrically distributed along the PPR pipe; and finally, acquiring the internal force of the PHC tubular pile, so that the test is convenient and simple, the acquisition accuracy of the internal force of the PHC tubular pile is improved, the construction of the PHC tubular pile with multiple sections is effectively adapted, and a side resistance curve is ensured to be continuous and smooth.
8. According to the invention, the constraint polynomial fitting is carried out on the test strain value data, so that the test error is reduced, and the reliability of the side resistance analysis result is improved.
In conclusion, the invention has reasonable design, is convenient for implanting optical fibers, has small influence on the construction of the PHC tubular pile and ensures the accurate internal force test of the PHC tubular pile.
The technical solution of the present invention is further described in detail by the accompanying drawings and embodiments.
Drawings
Fig. 1 is a schematic structural view of the device for testing the internal force of the PHC pile according to the present invention.
Fig. 2 is a schematic structural view of a first lower groove and a second lower groove of the device for testing the internal force of the PHC pile by using optical fibers according to the present invention.
Fig. 3 is a schematic structural view of an arc-shaped rotary groove of the device for testing the internal force of the PHC pile by using an optical fiber according to the present invention.
Fig. 4 is a flow chart of a method for testing the internal force of the PHC pile by using an optical fiber according to the present invention.
Description of reference numerals:
1-a PPR tube; 2-pipe joint; 3-a first groove;
4-a second groove; 5, an arc-shaped rotary groove; 5-1 — a first lower groove;
5-2 — a second lower groove; 6, a centralizer; 7-PHC tubular pile;
8-an optical fiber; 8-1 — a first section of optical fiber; 8-2-a second segment of optical fiber;
9-grouting layer; 10, anchoring piles; 11-pile cap;
12-fiber demodulation instrument; 13-end plate; 14-a jack;
15-a cross beam; 16-middle beam.
Detailed Description
As shown in fig. 1 to 3, the device for testing the internal force of the PHC tubular pile by using the optical fiber comprises an optical fiber structure extending into the PHC tubular pile 7 and an optical fiber demodulator 12 connected with the optical fiber structure, the top of the PHC tubular pile 7 is provided with a load loading mechanism, the optical fiber structure comprises an optical fiber implantation tube and optical fibers 8 arranged on the optical fiber implantation tube, the optical fiber implantation tube comprises a plurality of sections of sequentially connected PPR tubes 1, two adjacent sections of the PPR tubes 1 are connected by tube joints 2, each tube joint 2 is symmetrically provided with a first groove 3 and a second groove 4, the lower part of the optical fiber implantation tube is symmetrically provided with a first lower groove 5-1 and a second lower groove 5-2 and an arc-shaped rotary groove 5 for communicating the first lower groove 5-1 with the second lower groove 5-2, the optical fibers 8 comprise a plurality of optical fibers arranged in the first lower groove 5-1, The middle optical fibers in the arc-shaped rotary groove 5 and the second lower groove 5-2, the first section of optical fiber 8-1 arranged through the first groove 3 and the second section of optical fiber 8-2 arranged through the second groove 4 are symmetrically arranged along the PPR pipe 1;
the load loading mechanism includes a jack 14 and a reaction force transmitting member.
In this embodiment, the marking lines on the PPR tubes of the respective sections are located on the same vertical line, and the projection of the first section of the optical fiber 8-1 on the PPR tube 1 and the marking lines on the PPR tubes of the respective sections are located on the same vertical line.
In the embodiment, the center of the PPR pipe 1 and the center of the PHC tubular pile 7 are coaxially arranged, and the distance between the bottom of the optical fiber 8 and the end plate 13 at the bottom of the PHC tubular pile 7 is 20-30 cm;
the PHC tubular pile is characterized in that a grouting layer 9 is filled between the PHC tubular pile 7 and the PPR pipe 1, waterproof adhesive tapes are arranged at intervals of 30 cm-50 cm in the depth direction of the pile body between the first section of optical fiber 8-1 and the second section of optical fiber 8-2, and the waterproof adhesive tapes are additionally arranged at the positions of the first groove 3 and the second groove 4.
A method for testing the internal force of a PHC pile using an optical fiber, as shown in fig. 4, comprises the following steps:
step one, pre-connecting an optical fiber implantation tube:
101, connecting a plurality of sections of PPR pipes 1 to form an optical fiber implantation pipe;
102, symmetrically forming a first groove 3 and a second groove 4 on each pipe joint 2 by using an angle grinder;
103, arranging an arc-shaped rotary groove 5, a first lower groove 5-1 and a second lower groove 5-2 on the lower part of the optical fiber implantation tube by using an angle grinder; the first lower groove 5-1, the arc-shaped rotary groove 5 and the second lower groove 5-2 are sequentially connected, the first lower groove 5-1 and the second lower groove 5-2 are symmetrically arranged, and the bottom of the arc-shaped rotary groove 5 is higher than the bottom of the optical fiber implantation tube;
step two, optical fiber layout:
step 201, installing the middle part of the optical fiber to be laid into an arc-shaped rotary groove 5, bonding and fixing the optical fiber by using glue, and then winding the optical fiber and the optical fiber implantation tube by using a waterproof adhesive tape;
202, laying the optical fibers extending out of the arc-shaped rotary groove 5 along the optical fiber implantation tube; wherein, a first section of optical fiber 8-1 extending out of the arc-shaped rotary groove 5 sequentially passes through the first lower groove 5-1 and the first groove 3 from bottom to top, a first section of optical fiber 8-1 extending out of the arc-shaped rotary groove 5 is arranged along a marking line on the PPR pipe, a second section of optical fiber 8-2 extending out of the arc-shaped rotary groove 5 sequentially passes through the second lower groove 5-2 and the second groove 4 from bottom to top, and a second section of optical fiber 8-2 extending out of the arc-shaped rotary groove 5 and a first section of optical fiber 8-1 extending out of the arc-shaped rotary groove 5 are symmetrically arranged along the PPR pipe 1;
step three, implanting and grouting the optical fiber:
301, installing the optical fiber implantation tube into the PHC tubular pile 7; the PHC tubular pile 7 comprises a plurality of PHC tubular pile sections which are sequentially arranged from bottom to top, and the top of the PHC tubular pile 7 is positioned at a designed pile top elevation value;
step 302, connecting a light-transmitting pen with the extending end of the optical fiber 8 through an optical fiber jumper to judge that the optical fiber 8 is normal;
step 303, injecting slurry between the PHC tubular pile 7 and the PPR tube 1 from bottom to top by using a slurry injection pump through a slurry injection tube to obtain a slurry injection layer 9;
step four, testing the strain value of the PHC tubular pile:
step 401, operating a load loading mechanism to apply load to the PHC tubular pile 7, and detecting strain values corresponding to the depths of all pile bodies through an optical fiber demodulator 12; wherein, the extending end of the optical fiber 8 is connected with the optical fiber demodulator 12;
step 402, repeating the step 401 for multiple times, and applying multiple loads to the PHC tubular pile 7 to obtain strain values corresponding to the depths of pile bodies when the loads are applied;
step 403, in the process that no load is applied to the PHC tubular pile 7, sending the multiple groups of strain initial values detected by the optical fiber demodulator 12 to the data processor; the data processor records the depth of the pile body smaller than the design value of the breakpoint of the depth of the pile body as the depth of the upper pile body, and the depth of the ith upper pile body in the depth of the plurality of upper pile bodies
Figure GDA0002881567760000141
The corresponding strain initial value is recorded as the ith upper pile body depth
Figure GDA0002881567760000142
Corresponding first strain initial value
Figure GDA0002881567760000143
And ith upper shaft depth
Figure GDA00028815677600001414
Corresponding second strain initial value
Figure GDA0002881567760000144
Recording the depth of the pile body not less than the design value of the breakpoint depth of the pile body as the depth of the lower pile body by the data processor, and recording the depths of the lower pile bodiesDepth of ith' lower pile body
Figure GDA0002881567760000145
The corresponding strain initial value is recorded as the depth of the first section of optical fiber 8-1 at the ith' lower shaft
Figure GDA0002881567760000146
First initial value of strain at cross section
Figure GDA0002881567760000147
And the depth of the second section of optical fiber 8-2 at the ith' lower shaft
Figure GDA0002881567760000148
Second initial value of strain at cross section
Figure GDA0002881567760000149
Wherein i and i' are positive integers; i is more than or equal to 1 and less than or equal to m, m is a positive integer not less than 6, m represents the total number of the depth strain values of the upper pile body, i 'is more than or equal to 1 and less than or equal to m', m 'is a positive integer not less than 6, and m' represents the total number of the depth strain values of the lower pile body;
404, in the process of applying the jth load to the PHC tubular pile 7, detecting multiple groups of strain values by the optical fiber demodulator 12 and sending the strain values to the data processor;
when the jth load is loaded, the depth of the pile body is smaller than the design value z of the breakpoint of the depth of the pile bodyd,sThen, any upper pile depth strain value detected by the optical fiber demodulator 12 is recorded as the depth of the ith upper pile depth of the first section of optical fiber 8-1 at the jth applied load
Figure GDA00028815677600001410
First strain value measured at cross section
Figure GDA00028815677600001411
And the depth of the second section of optical fiber 8-2 at the ith upper shaft under the jth applied load
Figure GDA00028815677600001412
Measured second strain value at cross section
Figure GDA00028815677600001413
J is a positive integer, j is more than or equal to 1 and less than or equal to M, M represents the total number of times of load loading, and M is a positive integer more than 1;
when the data processor is adopted, the depth of the pile body is not less than the design value z of the breakpoint depth of the pile body when the jth load is loadedd,sThen, any lower pile depth strain value detected by the optical fiber demodulator 12 is recorded as the depth of the ith lower pile of the first section of optical fiber 8-1 at the jth applied load
Figure GDA0002881567760000151
First strain value measured at cross section
Figure GDA0002881567760000152
And the depth of the second section of optical fiber 8-2 at the ith' lower shaft under the jth applied load
Figure GDA0002881567760000153
Measured second strain value at cross section
Figure GDA0002881567760000154
Step five, fitting treatment of strain values of the PHC tubular pile:
step 501, adopting the data processor according to a formula
Figure GDA0002881567760000155
Obtaining the ith upper pile body depth under the jth applied load
Figure GDA0002881567760000156
Average value of measured strain at cross section
Figure GDA0002881567760000157
Using said data processor according to a formula
Figure GDA0002881567760000158
Obtaining the ith' lower pile depth under the jth applied load
Figure GDA0002881567760000159
Measured average value of strain of
Figure GDA00028815677600001510
Step 502, establishing an upper depth strain value fitting polynomial using the data processor
Figure GDA00028815677600001511
Wherein, akRepresenting a monomial upper coefficient when the degree of a monomial in the upper depth strain value fitting polynomial is K, wherein z represents the upper pile body depth independent variable, epsilon (z) represents the upper fitting strain, K and K are positive integers, K is more than or equal to 0 and less than or equal to K, and K represents the highest degree of the upper depth strain value fitting polynomial;
establishing a fitting polynomial of lower depth strain values using the data processor
Figure GDA00028815677600001512
Wherein, a'k′The lower coefficient of a monomial in the lower depth strain value fitting polynomial is represented when the degree of the monomial is K ', z ' represents the lower pile body depth independent variable, epsilon ' (z ') represents the lower fitting strain, K ' and K ' are positive integers, K ' is more than or equal to 0 and less than or equal to K ', and K ' represents the highest degree of the lower depth strain value fitting polynomial;
step 503, respectively taking the m upper pile body depths in the j-th load application as upper pile body depth independent variables by adopting the data processor, and establishing an independent variable upper pile body depth matrix
Figure GDA0002881567760000161
Respectively taking the depth of m' lower pile bodies in the jth applied load as the depth independent variable of the lower pile bodies, and establishing an independent variable lower pile body depth matrix
Figure GDA0002881567760000162
Step 504, the data processor is adopted to respectively take the m measured strain average values corresponding to the m upper pile body depths during the jth applied load as upper strain values, and an upper strain value matrix is established
Figure GDA0002881567760000163
The upper coefficient of each monomial in the upper depth strain value fitting polynomial is recorded as an upper coefficient matrix A ═ a0 a1 a2 … ak … aK]T；
Respectively taking m 'measured strain average values corresponding to m' lower pile body depths during the jth load application as lower strain values by adopting the data processor, and establishing a lower strain value matrix
Figure GDA0002881567760000164
The lower coefficients of the respective monomial equations in the lower depth strain value fitting polynomial are recorded as a lower coefficient matrix a '═ a'0 a′1 a′2 … a′k′ … a′K′]T；
Step 505, setting the length of the PHC tubular pile 7 to be L, and setting the depth of the ith upper pile body in the jth load loading by adopting the data processor
Figure GDA0002881567760000165
At the position of
Figure GDA0002881567760000166
And is less than the design value z of the depth breakpoint of the pile bodyd,sThe depth of any one upper pile body is recorded as the depth constraint value of the upper pile body
Figure GDA0002881567760000167
And the depth constraint value of the upper pile body during the jth load loading
Figure GDA0002881567760000171
The average value of the corresponding measured strain is
Figure GDA0002881567760000172
Depth of ith' lower pile body at jth load loading
Figure GDA0002881567760000173
At the position of
Figure GDA0002881567760000174
And is not less than the design value z of the depth breakpoint of the pile bodyd,sRecording the depth of any lower pile body as the depth constraint value of the lower pile body
Figure GDA0002881567760000175
And the depth constraint value of the lower pile body during the jth load loading
Figure GDA0002881567760000176
The average value of the corresponding measured strain is
Figure GDA0002881567760000177
Step 506, establishing an upper strain value fitting model by using the data processor, as follows:
Figure GDA0002881567760000178
wherein epsilon (A) is an upper strain value objective function, min represents a minimum value, s.t. represents a constraint condition, | · tory2A 2-norm representing a matrix; i | · | purple wind2Which is expressed as a square of the square of,
Figure GDA0002881567760000179
representing the first derivative of the independent variable about the depth of the upper pile body;
establishing a lower strain value fitting model by using the data processor, wherein the lower strain value fitting model is as follows:
Figure GDA00028815677600001710
wherein ε '(A') is the lower strain value objective function,
Figure GDA00028815677600001711
representing the first derivative of the independent variable about the depth of the lower pile body;
establishing a design value z of a pile body depth breakpoint by adopting the data processord,sThe strain value at (a) is fitted to the model as follows:
Figure GDA0002881567760000181
wherein the content of the first and second substances,
Figure GDA0002881567760000182
representing the second derivative with respect to the upper shaft depth argument,
Figure GDA0002881567760000183
representing the second derivative, epsilon, of the argument of depth of the lower shaftdDesign value z for representing pile body depth breakpointd,sThe corresponding measured strain average value;
and 507, solving the formula (I), (II) and (III) by using the data processor by using a least square method to obtain an upper coefficient matrix A ═ a0 a1 a2 … ak … aK]TAnd a lower coefficient matrix a '═ a'0 a′1 a′2 … a′k′ … a′K′]TTo obtain a fitting polynomial of the strain value of the upper depth
Figure GDA0002881567760000184
And a polynomial fit to the lower depth strain value
Figure GDA0002881567760000185
Step 508, using the data processor to determine the ith upper shaft depth at the jth applied load
Figure GDA0002881567760000186
Fitting polynomial into upper depth strain value
Figure GDA0002881567760000187
Obtaining the ith upper pile body depth under the jth applied load
Figure GDA0002881567760000188
Strain fit value at cross section
Figure GDA0002881567760000189
Using the data processor to determine the ith lower shaft depth at the jth applied load
Figure GDA00028815677600001810
Fitting polynomial into lower depth strain value
Figure GDA00028815677600001811
Obtaining the ith' lower pile depth under the jth applied load
Figure GDA00028815677600001812
Strain fit value at cross section
Figure GDA00028815677600001813
Step six, acquiring the internal force of the PHC tubular pile:
step 601, setting a plurality of upper pile body depths
Figure GDA00028815677600001814
Strain fit value at cross section
Figure GDA00028815677600001815
And a plurality of lower shaft depths
Figure GDA00028815677600001816
Strain fit value at cross section
Figure GDA00028815677600001817
Sequencing according to the sequence of the depth of the pile body from small to large, and sequencing a plurality of depth sections of the pile bodyThe p-th strain fitting value among the strain fitting values of (A) is recorded as
Figure GDA00028815677600001818
Wherein p is a positive integer, and p is more than or equal to 1 and less than or equal to m + m', the pth strain fitting value
Figure GDA00028815677600001819
The depth of the corresponding pile body is recorded as the depth z of the p-th pile bodyp；
Step 602, employing the data processor according to a formula
Figure GDA0002881567760000191
Obtaining the p-th pile body depth zpAxial force Q at the cross sectionp(ii) a Wherein E ispIndicating the p-th shaft depth zpModulus of elasticity, A, of pile body concrete at cross sectionpIndicating the p-th shaft depth zpThe cross section area of the pile body at the cross section;
step 603, using the data processor according to a formula
Figure GDA0002881567760000192
Obtaining the p-th pile body depth zpThe depth z of the p +1 th pile body at the sectionp+1Lateral resistance q at the cross sectionps(ii) a Wherein u represents the pile body perimeter of the PHC tubular pile 7, and lpIndicating the p-th shaft depth zpThe depth z of the p +1 th pile body at the sectionp+1Pile length at cross section, Qp+1Represents the p +1 th pile depth zp+1Axial force at the cross section.
In this embodiment, in step 101, two adjacent sections of the PPR pipe 1 are connected by a pipe joint 2, and the marking lines on the sections of the PPR pipe are located on the same vertical line;
in the step 102, a first groove 3 and a second groove 4 on each pipe joint 2 are symmetrically distributed along the PPR pipe 1, and the projection of the first section of optical fiber 8-1 on the PPR pipe 1 and the marking lines on each section of PPR pipe are positioned on the same vertical line;
in step 103, the radius of the arc-shaped rotary groove 5 is more than 20 times of the outer diameter of the optical fiber;
in the step 301, the center of the PPR pipe 1 and the center of the PHC tubular pile 7 are coaxially arranged, and the distance between the bottom of the optical fiber 8 and the end plate 13 at the bottom of the PHC tubular pile 7 is 20-30 cm;
in the step 303, the slurry is formed by mixing cement, bentonite and water, and the weight ratio of each part is 1000: 70-75: 1000.
the value range of the length L of the PHC tubular pile 7 in the step 505 is 30 m-40 m.
In this embodiment, in step 403, design value z of pile body depth breakpointd,sThe specific process of obtaining is as follows:
step 4031, in the process of applying a load to the PHC tubular pile 7 for one time, the multiple groups of strain values detected by the optical fiber demodulator 12 are sent to the data processor, and the data processor obtains the depth z 'of the first section of optical fiber 8-1 at the ith' individual pile bodyi″First strain value epsilon at cross sectioni″,1And the second section of optical fiber 8-2 is at the ith' pile depth zi″Second strain value epsilon at cross sectioni″,2(ii) a Wherein i' is a positive integer;
4032, using the data processor according to a formula
Figure GDA0002881567760000201
Obtaining the ith 'depth z' of pile body in one time of applying loadi″Measured average value of strain of
Figure GDA0002881567760000202
Wherein the content of the first and second substances,
Figure GDA0002881567760000203
indicating that the first segment of optical fiber 8-1 is at the ith "pile depth zi″A first initial value of strain at the cross-section,
Figure GDA0002881567760000204
indicating that the second segment of optical fiber 8-2 is at the ith "pile depth zi″A second initial value of strain at the cross-section;
4033, using the data processor according to a formula
Figure GDA0002881567760000205
Obtaining the ith 'depth z' of pile bodyi″Axial force Q 'at cross section'i′(ii) a Wherein, E'i′Indicates the ith "pile depth zi″Pile body concrete elastic modulus at section, A'i′Indicates the ith "pile depth zi″The cross section area of the pile body at the cross section;
4034, using the data processor according to a formula
Figure GDA0002881567760000206
Obtaining the ith 'depth z' of pile bodyi″The depth z between the cross section and the i' +1 th pile bodyi″+1Inter-side drag q 'at cross section'i′s(ii) a Wherein l'i′Indicates the ith "pile depth zi″The depth z between the cross section and the i' +1 th pile bodyi″+1Pile length, Q 'at cross section'i′+1Indicates the ith' +1 pile depth zi″+1Axial force at the cross section;
4035, using the data processor to determine the ith 'depth z' of the pile body by taking the depth of the pile body as the abscissa and the lateral resistance as the ordinatei″The depth z between the cross section and the i' +1 th pile bodyi″+1Inter-side drag q 'at cross section'i′sDrawing and fitting to obtain a side resistance curve;
4036, acquiring a minimum value point and a maximum value point of the side resistance curve by using the data processor, recording a small pile depth corresponding to the minimum value point as a minimum pile depth, recording a small pile depth corresponding to the maximum value as a maximum pile depth, and averaging the minimum pile depth and the maximum pile depth to obtain a pile depth breakpoint design value zd,s。
In this embodiment, the following steps are further performed between the second step and the third step:
step 203, laying waterproof adhesive tapes along the first section of optical fiber 8-1 extending out of the arc-shaped rotary groove 5 and the second section of optical fiber 8-2 extending out of the arc-shaped rotary groove 5 at intervals of 30-50 cm along the depth direction of the pile body; waterproof adhesive tapes are additionally arranged at the first groove 3 and the second groove 4;
and step 204, sleeving the centralizers 6 outside the two pipe joints 2 to complete the arrangement of the optical fiber implantation pipes.
In this embodiment, before applying a load to the PHC tubular pile 7 in step 401, a load loading mechanism needs to be provided, which includes the following steps:
step A, arranging a pile cap 11 above the PHC tubular pile 7, and penetrating the optical fiber 8 from the pile cap 11;
b, PHC, arranging anchor piles 10 on two sides of the tubular pile 7, and erecting a cross beam 15 on the two anchor piles 10;
step C, arranging a middle beam 16 at the bottom of the cross beam 15, and arranging a plurality of jacks 14 between the pile caps 11 and the middle beam 16;
step D, connecting the extending end of the optical fiber 8 with the optical fiber demodulator 12;
in step 401, the load loading mechanism is operated to apply a load to the PHC tubular pile 7, and the specific process is as follows: the jacks 14 are operated to extend, and the combined force of the jacks 14 applies load to the PHC tubular pile 7 through the pile cap 11; wherein the loading counter force of the jack 14 is transmitted to the anchor pile 10 through the intermediate beam 16 and the cross beam 15.
In this embodiment, design value z of depth breakpoint of pile bodyd,sCorresponding measured strain average value epsilondObtaining: when pile body depth breakpoint design value zd,sThe depth measuring positions of the upper pile body and the lower pile body which are adjacent are respectively marked as the depth of the first pile body
Figure GDA0002881567760000211
And a second shaft depth
Figure GDA0002881567760000212
Design value z of pile body depth breakpointd,sCorresponding measured strain average value epsilondFor the second pile body depth
Figure GDA0002881567760000213
Corresponding measured strain average values.
In this embodiment, it should be noted that the pth shaft depth z is representedpThe depth z of the p +1 th pile body at the sectionp+1Pile length l at cross sectionpAnd ith' depth of pile body zi″The depth z between the cross section and the i' +1 th pile bodyi″+1Pile length l 'at cross section'i′The value of (A) is 20 cm-50 cm.
In the embodiment, the maximum degree K of the upper depth strain value fitting polynomial ranges from 4 to 6, and the maximum degree K' of the lower depth strain value fitting polynomial ranges from 4 to 6.
In this embodiment, the data processor is a computer.
In this embodiment, it should be noted that the pile depth refers to a distance between the pile and the top of the PHC pile 7.
In this embodiment, the perimeter of the shaft of the PHC pile 7 refers to the perimeter of the cross section of the shaft of the PHC pile 7.
In this embodiment, it should be noted that T represents a transpose of a matrix.
In this embodiment, the optical fiber patch cord may be a single-mode FC-FC optical fiber patch cord.
In this embodiment, it should be noted that the fiber demodulation instrument 12 can refer to a fiber demodulation instrument of BOFDA (fTB 2505).
In this embodiment, it should be noted that the PHC tubular pile 7 is a PHC-AB500125 type tubular pile, the diameter of the PHC tubular pile 7 is 500mm, the length of the PHC tubular pile 7 is 32m, and the PHC tubular pile is formed by welding 3 PHC tubular pile sections sequentially arranged from bottom to top, and the lengths of the single PHC tubular pile sections from bottom to top are 11m, 11m and 10m, respectively.
In this embodiment, it should be noted that, in an actual use process, when L is equal to 32m, the design value of the breakpoint of the depth of the pile body is 12m, an upper strain value fitting model is established above 12m, a lower strain value fitting model is established below 12m, and the first derivatives of the upper strain value fitting model and the lower strain value fitting model at 12m and the second derivatives of the upper strain value fitting model and the lower strain value fitting model are all equal to each other, so as to ensure that the side resistance curve of the PHC tubular pile 7 is continuous and smooth.
In this embodiment, it is necessary toIt should be noted that, in the practical use process, the upper pile body depth constraint value zcs is 6m, and the depth of lower pile body is restricted
Figure GDA0002881567760000221
Is 26 m.
In this embodiment, it should be noted that, the PHC tubular pile 7 has a uniform pile diameter, and the pile body material of the PHC tubular pile 7 is uniform, so the actually measured strain of the PHC tubular pile 7 is much more regular along with the change of the depth, but in the actual process, the PHC tubular pile 7 includes a plurality of PHC tubular pile sections sequentially arranged from bottom to top, so the strain near the pile splicing position of the PHC tubular pile section is significantly large.
In conclusion, the method has the advantages of reasonable design, convenience in optical fiber implantation, small influence on the PHC tubular pile construction, reduction of test errors due to constraint polynomial fitting of test strain value data, and increase of reliability of side resistance analysis results, so that accurate internal force test of the PHC tubular pile is ensured.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and all simple modifications, changes and equivalent structural changes made to the above embodiment according to the technical spirit of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims (7)

1. A method for testing the internal force of a PHC tubular pile by using optical fibers comprises an optical fiber structure extending into the PHC tubular pile (7) and an optical fiber demodulator (12) connected with the optical fiber structure, wherein the top of the PHC tubular pile (7) is provided with a load loading mechanism, the optical fiber structure comprises an optical fiber implantation tube and optical fibers (8) arranged on the optical fiber implantation tube, the optical fiber implantation tube comprises a plurality of sections of PPR tubes (1) which are sequentially connected, two adjacent sections of the PPR tubes (1) are connected through tube joints (2), each tube joint (2) is symmetrically provided with a first groove (3) and a second groove (4), the lower part of the optical fiber implantation tube is symmetrically provided with a first lower groove (5-1) and a second lower groove (5-2) and an arc-shaped rotary groove (5) for communicating the first lower groove (5-1) with the second lower groove (5-2), the optical fiber (8) comprises a middle optical fiber which is arranged in the first lower groove (5-1), the arc-shaped rotary groove (5) and the second lower groove (5-2) in a penetrating mode, a first section of optical fiber (8-1) which is arranged to penetrate through the first groove (3) and a second section of optical fiber (8-2) which is arranged to penetrate through the second groove (4), and the second section of optical fiber (8-2) and the first section of optical fiber (8-1) are symmetrically arranged along the PPR pipe (1); the load loading mechanism comprises a jack (14) and a reaction force transmission component; the method is characterized by comprising the following steps:
step one, pre-connecting an optical fiber implantation tube:
101, connecting a plurality of sections of PPR pipes (1) to form an optical fiber implantation pipe;
102, symmetrically forming a first groove (3) and a second groove (4) on each pipe joint (2) by using an angle grinder;
103, forming an arc-shaped rotary groove (5), a first lower groove (5-1) and a second lower groove (5-2) on the lower part of the optical fiber implantation tube by using an angle grinder; the first lower groove (5-1), the arc-shaped rotary groove (5) and the second lower groove (5-2) are sequentially connected, the first lower groove (5-1) and the second lower groove (5-2) are symmetrically arranged, and the bottom of the arc-shaped rotary groove (5) is higher than the bottom of the optical fiber implantation tube;
step two, optical fiber layout:
step 201, installing the middle part of the optical fiber to be laid into an arc-shaped rotary groove (5), bonding and fixing the optical fiber by using glue, and then winding the optical fiber and the optical fiber implantation tube by using a waterproof adhesive tape;
202, laying the optical fibers extending out of the arc-shaped rotary groove (5) along the optical fiber implantation tube; wherein, a first section of optical fiber (8-1) extending out of the arc-shaped rotary groove (5) sequentially passes through the first lower groove (5-1) and the first groove (3) from bottom to top, a first section of optical fiber (8-1) extending out of the arc-shaped rotary groove (5) is arranged along a marking line on the PPR pipe, a second section of optical fiber (8-2) extending out of the arc-shaped rotary groove (5) sequentially passes through the second lower groove (5-2) and the second groove (4) from bottom to top, and a second section of optical fiber (8-2) extending out of the arc-shaped rotary groove (5) and a first section of optical fiber (8-1) extending out of the arc-shaped rotary groove (5) are symmetrically arranged along the PPR pipe (1);
step three, implanting and grouting the optical fiber:
step 301, installing the optical fiber implantation tube into a PHC tubular pile (7); the PHC tubular pile (7) comprises a plurality of PHC tubular pile sections which are sequentially arranged from bottom to top, and the top of the PHC tubular pile (7) is positioned at a designed elevation value of the pile top;
step 302, connecting a light-transmitting pen with the extending end of the optical fiber (8) through an optical fiber jumper to judge that the optical fiber (8) is normal;
step 303, injecting slurry between the PHC tubular pile (7) and the PPR tube (1) from bottom to top by using a slurry injection pump through a slurry injection tube to obtain a slurry injection layer (9);
step four, testing the strain value of the PHC tubular pile:
step 401, operating a load loading mechanism to apply load to the PHC tubular pile (7), and detecting strain values corresponding to the depths of all pile bodies through an optical fiber demodulator (12); wherein, the extending end of the optical fiber (8) is connected with the optical fiber demodulator (12);
step 402, repeating the step 401 for multiple times, applying multiple loads to the PHC tubular pile (7), and obtaining strain values corresponding to the depths of pile bodies when the loads are applied;
step 403, in the process that no load is applied to the PHC tubular pile (7), sending a plurality of groups of strain initial values detected by the optical fiber demodulator (12) to a data processor; wherein the data processor is smaller than the design value z of the depth breakpoint of the pile bodyd,sThe depth of the upper pile body is recorded as the depth of the upper pile body, and the ith depth of the upper pile body in the plurality of depths of the upper pile body
Figure FDA0002881567750000021
The corresponding strain initial value is recorded as the ith upper pile body depth
Figure FDA0002881567750000022
Corresponding first strain initial value
Figure FDA0002881567750000023
And ith upper shaft depth
Figure FDA0002881567750000024
Corresponding second strain initial value
Figure FDA0002881567750000025
The data processor will not be less than the design value z of the depth breakpoint of the pile bodyd,sThe depth of the lower pile body is recorded as the depth of the lower pile body, i' th lower pile body depth in the plurality of lower pile body depths
Figure FDA0002881567750000026
The corresponding strain initial value is recorded as the depth of the first section of optical fiber (8-1) at the ith' lower shaft
Figure FDA0002881567750000031
First initial value of strain at cross section
Figure FDA0002881567750000032
And the depth of the second section of optical fiber (8-2) at the ith' lower shaft
Figure FDA0002881567750000033
Second initial value of strain at cross section
Figure FDA0002881567750000034
Wherein i and i' are positive integers; i is more than or equal to 1 and less than or equal to m, m is a positive integer not less than 6, m represents the total number of the depth strain values of the upper pile body, i 'is more than or equal to 1 and less than or equal to m', m 'is a positive integer not less than 6, and m' represents the total number of the depth strain values of the lower pile body;
404, in the process of applying the jth load to the PHC tubular pile (7), detecting multiple groups of strain values by the optical fiber demodulator (12) and sending the strain values to the data processor;
when the jth load is loaded, the depth of the pile body is smaller than the design value z of the breakpoint of the depth of the pile bodyd,sThen, any upper pile depth strain value detected by the optical fiber demodulator (12) is recorded as the depth of the first section of optical fiber (8-1) at the ith upper pile depth when the j applied load is carried out
Figure FDA0002881567750000035
First strain value measured at cross section
Figure FDA0002881567750000036
And the second segment of optical fiber (8-2) is at the ith upper shaft depth under the jth applied load
Figure FDA0002881567750000037
Measured second strain value at cross section
Figure FDA0002881567750000038
J is a positive integer, j is more than or equal to 1 and less than or equal to M, M represents the total number of times of load loading, and M is a positive integer more than 1;
when the data processor is adopted, the depth of the pile body is not less than the design value z of the breakpoint depth of the pile body when the jth load is loadedd,sThen, any lower pile depth strain value detected by the optical fiber demodulator (12) is recorded as the depth of the ith lower pile when the j applied load is applied to the first section of optical fiber (8-1)
Figure FDA0002881567750000039
First strain value measured at cross section
Figure FDA00028815677500000310
And the depth of the second section of optical fiber (8-2) at the ith' lower shaft under the jth applied load
Figure FDA00028815677500000311
Measured second strain value at cross section
Figure FDA00028815677500000312
Step five, fitting treatment of strain values of the PHC tubular pile:
step 501, adopting the data processor according to a formula
Figure FDA00028815677500000313
Obtaining the ith upper pile body depth under the jth applied load
Figure FDA00028815677500000314
Average value of measured strain at cross section
Figure FDA00028815677500000315
Using said data processor according to a formula
Figure FDA00028815677500000316
Obtaining the ith' lower pile depth under the jth applied load
Figure FDA00028815677500000317
Measured average value of strain of
Figure FDA00028815677500000318
Step 502, establishing an upper depth strain value fitting polynomial using the data processor
Figure FDA00028815677500000319
Wherein, akRepresenting a monomial upper coefficient when the degree of a monomial in the upper depth strain value fitting polynomial is K, wherein z represents the upper pile body depth independent variable, epsilon (z) represents the upper fitting strain, K and K are positive integers, K is more than or equal to 0 and less than or equal to K, and K represents the highest degree of the upper depth strain value fitting polynomial;
establishing a fitting polynomial of lower depth strain values using the data processor
Figure FDA0002881567750000041
Wherein, a'k′The lower coefficient of a monomial in the lower depth strain value fitting polynomial is represented when the degree of the monomial is K ', z ' represents the lower pile body depth independent variable, epsilon ' (z ') represents the lower fitting strain, K ' and K ' are positive integers, K ' is more than or equal to 0 and less than or equal to K ', and K ' represents the highest degree of the lower depth strain value fitting polynomial;
step 503, using the data processor to take the depth of m upper pile bodies as the upper depth when the load is applied for the jth timeIndependent variable of partial pile body depth and establishing independent variable upper pile body depth matrix
Figure FDA0002881567750000042
Respectively taking the depth of m' lower pile bodies in the jth applied load as the depth independent variable of the lower pile bodies, and establishing an independent variable lower pile body depth matrix
Figure FDA0002881567750000043
Step 504, the data processor is adopted to respectively take the m measured strain average values corresponding to the m upper pile body depths during the jth applied load as upper strain values, and an upper strain value matrix is established
Figure FDA0002881567750000044
The upper coefficient of each monomial in the upper depth strain value fitting polynomial is recorded as an upper coefficient matrix A ═ a0 a1 a2…ak…aK]T；
Respectively taking m 'measured strain average values corresponding to m' lower pile body depths during the jth load application as lower strain values by adopting the data processor, and establishing a lower strain value matrix
Figure FDA0002881567750000051
The lower coefficients of the respective monomial equations in the lower depth strain value fitting polynomial are recorded as a lower coefficient matrix a '═ a'0 a′1 a′2…a′k′…a′K′]T；
505, setting the length of the PHC tubular pile (7) to be L, and setting the depth of the ith upper pile body in the j load loading process by adopting the data processor
Figure FDA0002881567750000052
At the position of
Figure FDA0002881567750000053
And is less than the design value z of the depth breakpoint of the pile bodyd,sThe depth of any one upper pile body is recorded as the depth constraint value of the upper pile body
Figure FDA0002881567750000054
And the depth constraint value of the upper pile body during the jth load loading
Figure FDA0002881567750000055
The average value of the corresponding measured strain is
Figure FDA0002881567750000056
Depth of ith' lower pile body at jth load loading
Figure FDA0002881567750000057
At the position of
Figure FDA0002881567750000058
And is not less than the design value z of the depth breakpoint of the pile bodyd,sRecording the depth of any lower pile body as the depth constraint value of the lower pile body
Figure FDA0002881567750000059
And the depth constraint value of the lower pile body during the jth load loading
Figure FDA00028815677500000510
The average value of the corresponding measured strain is
Figure FDA00028815677500000511
Step 506, establishing an upper strain value fitting model by using the data processor, as follows:
Figure FDA00028815677500000512
wherein ε (A) is an upper strain value objective function, min represents a minimum value, and s.t. representsConstraint condition, | · | luminance2A 2-norm representing a matrix; i | · | purple wind2Which is expressed as a square of the square of,
Figure FDA00028815677500000513
representing the first derivative of the independent variable about the depth of the upper pile body;
establishing a lower strain value fitting model by using the data processor, wherein the lower strain value fitting model is as follows:
Figure FDA0002881567750000061
wherein ε '(A') is the lower strain value objective function,
Figure FDA0002881567750000062
representing the first derivative of the independent variable about the depth of the lower pile body;
establishing a design value z of a pile body depth breakpoint by adopting the data processord,sThe strain value at (a) is fitted to the model as follows:
Figure FDA0002881567750000063
wherein the content of the first and second substances,
Figure FDA0002881567750000064
representing the second derivative with respect to the upper shaft depth argument,
Figure FDA0002881567750000065
representing the second derivative, epsilon, of the argument of depth of the lower shaftdDesign value z for representing pile body depth breakpointd,sThe corresponding measured strain average value;
and 507, solving the formula (I), (II) and (III) by using the data processor by using a least square method to obtain an upper coefficient matrix A ═ a0 a1 a2…ak…aK]TAnd a lower coefficient matrix a '═ a'0 a′1 a′2…a′k′…a′K′]TTo obtain a fitting polynomial of the strain value of the upper depth
Figure FDA0002881567750000066
And a polynomial fit to the lower depth strain value
Figure FDA0002881567750000067
Step 508, using the data processor to determine the ith upper shaft depth at the jth applied load
Figure FDA0002881567750000068
Substituting the upper depth strain value into a fitting polynomial to obtain the ith upper pile body depth in the jth applied load
Figure FDA0002881567750000069
Strain fit value at cross section
Figure FDA00028815677500000610
Using the data processor to determine the ith lower shaft depth at the jth applied load
Figure FDA00028815677500000611
Substituting the lower depth strain value into a fitting polynomial to obtain the ith lower pile body depth under the jth applied load
Figure FDA0002881567750000071
Strain fit value at cross section
Figure FDA0002881567750000072
Step six, acquiring the internal force of the PHC tubular pile:
step 601, setting a plurality of upper pile body depths
Figure FDA0002881567750000073
Strain fit value at cross section
Figure FDA0002881567750000074
And a plurality of lower shaft depths
Figure FDA0002881567750000075
Strain fit value at cross section
Figure FDA0002881567750000076
Sequencing according to the sequence of the depth of the pile body from small to large, and recording the p-th strain fitting value in the strain fitting values of the depth sections of the pile bodies as
Figure FDA0002881567750000077
Wherein p is a positive integer, and p is more than or equal to 1 and less than or equal to m + m', the pth strain fitting value
Figure FDA0002881567750000078
The depth of the corresponding pile body is recorded as the depth z of the p-th pile bodyp；
Step 602, employing the data processor according to a formula
Figure FDA0002881567750000079
Obtaining the p-th pile body depth zpAxial force Q at the cross sectionp(ii) a Wherein E ispIndicating the p-th shaft depth zpModulus of elasticity, A, of pile body concrete at cross sectionpIndicating the p-th shaft depth zpThe cross section area of the pile body at the cross section;
step 603, using the data processor according to a formula
Figure FDA00028815677500000710
Obtaining the p-th pile body depth zpThe depth z of the p +1 th pile body at the sectionp+1Lateral resistance q at the cross sectionps(ii) a Wherein u represents the perimeter of the body of the PHC tubular pile (7), and lpIndicating the p-th shaft depth zpAt the cross section with the p +1 thDepth z of pile bodyp+1Pile length at cross section, Qp+1Represents the p +1 th pile depth zp+1Axial force at the cross section.
2. The method for testing the internal force of the PHC tubular pile by using the optical fiber as claimed in claim 1, wherein: the marking lines on the PPR pipes of all sections are located on the same vertical line, and the projection of the first section of optical fiber (8-1) on the PPR pipe (1) and the marking lines on the PPR pipes of all sections are located on the same vertical line.
3. The method for testing the internal force of the PHC tubular pile by using the optical fiber as claimed in claim 1, wherein: the center of the PPR pipe (1) and the center of the PHC pipe pile (7) are coaxially arranged, and the distance between the bottom of the optical fiber (8) and an end plate (13) at the bottom of the PHC pipe pile (7) is 20-30 cm;
fill slip casting layer (9) between PHC tubular pile (7) and PPR pipe (1), waterproof sticky tape is laid along stake body depth direction interval 30cm ~ 50cm in first section optic fibre (8-1) and second section optic fibre (8-2), waterproof sticky tape is established in first recess (3) and second recess (4) department with adding.
4. The method for testing the internal force of the PHC tubular pile by using the optical fiber as claimed in claim 1, wherein: in the step 101, two adjacent sections of PPR pipes (1) are connected through pipe joints (2), and marking lines on the PPR pipes are positioned on the same vertical line;
in the step 102, a first groove (3) and a second groove (4) on each pipe joint (2) are symmetrically distributed along the PPR pipe (1), and the projection of the first section of optical fiber (8-1) on the PPR pipe (1) and the marking lines on each section of PPR pipe are positioned on the same vertical line;
in step 103, the radius of the arc-shaped rotary groove (5) is more than 20 times of the outer diameter of the optical fiber;
in the step 301, the center of the PPR pipe (1) and the center of the PHC pipe pile (7) are coaxially arranged, and the distance between the bottom of the optical fiber (8) and an end plate (13) at the bottom of the PHC pipe pile (7) is 20-30 cm;
in the step 303, the slurry is formed by mixing cement, bentonite and water, and the weight ratio of each part is 1000: (70-75): 1000, parts by weight;
the value range of the length L of the PHC tubular pile (7) in the step 505 is 30-40 m.
5. The method for testing the internal force of the PHC tubular pile by using the optical fiber as claimed in claim 1, wherein: pile body depth breakpoint design value z in step 403d,sThe specific process of obtaining is as follows:
step 4031, in the process of applying a load to the PHC tubular pile (7) for one time, a plurality of groups of strain values detected by the optical fiber demodulator (12) are sent to the data processor, and the data processor obtains the ith 'pile body depth z' of the first section of optical fiber (8-1)i″First strain value epsilon at cross sectioni″,1And the second section of optical fiber (8-2) is arranged at the ith' pile body depth zi″Second strain value epsilon at cross sectioni″,2(ii) a Wherein i' is a positive integer;
4032, using the data processor according to a formula
Figure FDA0002881567750000081
Obtaining the ith 'depth z' of pile body in one time of applying loadi″Measured average value of strain of
Figure FDA0002881567750000082
Wherein the content of the first and second substances,
Figure FDA0002881567750000083
indicates that the first section of the optical fiber (8-1) is at the ith' pile body depth zi″A first initial value of strain at the cross-section,
Figure FDA0002881567750000091
indicates that the second segment of the optical fiber (8-2) is at the ith' pile body depth zi″A second initial value of strain at the cross-section;
4033, using the data processor according to a formula
Figure FDA0002881567750000092
Obtaining the ith 'depth z' of pile bodyi″Axial force Q 'at cross section'i″(ii) a Wherein, E'i″Indicates the ith "pile depth zi″Pile body concrete elastic modulus at section, A'i″Indicates the ith "pile depth zi″The cross section area of the pile body at the cross section;
4034, using the data processor according to a formula
Figure FDA0002881567750000093
Obtaining the ith 'depth z' of pile bodyi″The depth z between the cross section and the i' +1 th pile bodyi″+1Inter-side drag q 'at cross section'i″s(ii) a Wherein l'i″Indicates the ith "pile depth zi″The depth z between the cross section and the i' +1 th pile bodyi″+1Pile length, Q 'at cross section'i″+1Indicates the ith' +1 pile depth zi″+1Axial force at the cross section;
4035, using the data processor to determine the ith 'depth z' of the pile body by taking the depth of the pile body as the abscissa and the lateral resistance as the ordinatei″The depth z between the cross section and the i' +1 th pile bodyi″+1Inter-side drag q 'at cross section'i″sDrawing and fitting to obtain a side resistance curve;
4036, acquiring a minimum value point and a maximum value point of the side resistance curve by using the data processor, recording a small pile depth corresponding to the minimum value point as a minimum pile depth, recording a small pile depth corresponding to the maximum value as a maximum pile depth, and averaging the minimum pile depth and the maximum pile depth to obtain a pile depth breakpoint design value zd,s。
6. The method for testing the internal force of the PHC tubular pile by using the optical fiber as claimed in claim 1, wherein: the following steps are also carried out between the second step and the third step:
step 203, laying waterproof adhesive tapes along a first section of optical fiber (8-1) extending out of the arc-shaped rotary groove (5) and a second section of optical fiber (8-2) extending out of the arc-shaped rotary groove (5) at intervals of 30-50 cm along the depth direction of the pile body; wherein, waterproof adhesive tapes are additionally arranged at the first groove (3) and the second groove (4);
and step 204, sleeving a centralizer (6) outside the two pipe joints (2) to complete the arrangement of the optical fiber implantation pipes.
7. The method for testing the internal force of the PHC tubular pile by using the optical fiber as claimed in claim 1, wherein: in step 401, before applying a load to the PHC pile (7), a load loading mechanism needs to be set, which includes the following steps:
a, arranging a pile cap (11) above a PHC pipe pile (7), and penetrating an optical fiber (8) from the pile cap (11);
b, PHC, arranging anchor piles (10) on two sides of the tubular pile (7), and erecting a cross beam (15) on the two anchor piles (10);
step C, arranging a middle beam (16) at the bottom of the cross beam (15), and arranging a plurality of jacks (14) between the pile cap (11) and the middle beam (16);
d, connecting the extending end of the optical fiber (8) with an optical fiber demodulator (12);
in the step 401, the load loading mechanism is operated to apply a load to the PHC tubular pile (7), and the specific process is as follows: operating the jacks (14) to extend, and applying load to the PHC tubular pile (7) through a pile cap (11) by the combined force of the jacks (14); wherein the loading counter force of the jack (14) is transmitted to the anchor pile (10) through the middle beam (16) and the cross beam (15).
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