CN111710226A - Multi-working-condition simulation combination device for low-strain detection of foundation pile - Google Patents
Multi-working-condition simulation combination device for low-strain detection of foundation pile Download PDFInfo
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Abstract
The invention relates to a multi-working-condition simulation combination device for low-strain detection of foundation piles, which comprises a cylindrical simulation pile, wherein a shading bag is sleeved outside the simulation pile, the simulation pile comprises at least one first pile body, a first threaded column is arranged at the head end of the first pile body, and a first screw hole matched with the first threaded column is arranged at the tail end of the first pile body; the simulation pile further comprises a male end socket and a female end socket, the male end socket comprises a cylindrical first column body, and a second threaded column matched with the first screw hole is arranged at the head end of the first column body; the tail end of the second column body is provided with a second screw hole matched with the first threaded column. The multi-working-condition simulation combination device for the low-strain detection of the foundation pile has the advantages of small occupied area, simplicity and convenience in installation and disassembly, low cost and small limitation of a site; after random combination, the simulated defect samples have large quantity and good implementation effect.
Description
Technical Field
The invention relates to a multi-working-condition simulation combination device for low-strain detection of foundation piles, and belongs to the technical field of low-strain detection.
Background
The foundation engineering is an important component of construction engineering, the quality of the foundation engineering is directly related to the structural safety of the whole building, so the acceptance of the pile quality of the foundation pile is very important, and according to the requirements of the national standard of the people's republic of China (building foundation design Specification) GB50007-2011 and the industry standard of the people's republic of China (building foundation pile detection technical Specification) JGJ/T106-.
The low strain reflection wave method is characterized in that a foundation pile is assumed to be a one-dimensional rod piece with one end elastically connected, the material is uniform and continuous, signals are not attenuated in the process of propagating along a pile body, and the propagation of the stress wave of the pile body is not influenced by soil around the pile. The method is characterized in that vertical excitation is carried out on the pile top, elastic waves are transmitted downwards along the pile body, when the waves are transmitted along the pile body and meet the change of impedance (such as the pile bottom or the defects of the pile body), stress waves are reflected, a high-sensitivity sensor arranged on the pile top receives response signals, and after amplification, filtering and data processing, reflection information from different parts of the pile body can be identified, so that the integrity of the pile body is judged according to the reflection information, and the defect type and the position of the defect type in the pile body are deduced. When detecting pile end reflection information or deep defects of a long pile, selecting a sensor with good low-frequency performance; when detecting a short pile or a shallow part defect of a pile, an acceleration sensor or a broadband speed sensor is selected.
According to a low-strain detection theory and the actual situation of field detection, when the integrity of the pile body is detected under low strain, firstly, a high-quality reflection waveform containing the impedance change information of the pile body is acquired, then, comprehensive judgment is carried out according to the acquired low-strain reflection waveform in combination with geological and pile-forming data collected on the field, and otherwise, misjudgment can be caused.
Therefore, in the low-strain detection process of the foundation pile, the judgment of an inspector on the ideal reflected wave waveform obtained by field detection and the judgment of the integrity of the pile body by collecting the reflected waveform indoors in a combined manner are the most important 2 links, namely the inspector of the foundation pile is required to be familiar with and master the reflection characteristics of the stress wave and the reflected wave characteristics of various defects of the stress wave in the pile.
Therefore, it is not easy to cultivate an experienced foundation pile low-strain inspector, which not only requires the inspector to be familiar with the low-strain inspection theory, but also needs to cultivate the inspector to be capable of accurately judging the defects in the pile by combining the collected foundation pile reflected wave waveform.
At present, an effective method for cultivating comprehensive analysis level of inspectors is to acquire analysis experience in the actual foundation pile low-strain detection process through examination of a concrete simulation pile, and the concrete simulation pile is also widely used for practical operation examination of training institutions or construction administration departments on the foundation pile low-strain inspectors of various detection institutions.
Through the practical operation and examination of the concrete simulation pile close to the actual situation, although the concrete simulation pile is an effective way for training or examining a foundation pile low-strain detector, the following problems also exist:
1. the general detection mechanism or the training mechanism office place are all in urban areas, are influenced by factors such as the limitation of sites and construction processes, high manufacturing cost and the like, the number of concrete simulation piles arranged in general units is limited, and the types and positions of defects in the concrete simulation piles which can be arranged are limited.
2. A plurality of defect conditions which can appear in the actual detection process are difficult to simulate by the limited concrete simulation piles, and the comprehensive analysis level of various defect conditions which can be responded by an inspector is difficult to cultivate by only the limited concrete simulation piles.
3. Due to the reasons 1 and 2, typical defect samples which can be simulated in pile foundation construction of a common concrete simulation pile base are limited, the set defects cannot be changed, large-scale examination or subsequent students can easily pass the examination according to defect waveforms brought by the examination of the previous students, and the theoretical analysis level of the examined students on actual measurement defects cannot be achieved.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides a multi-working-condition simulation combination device for low strain detection of a foundation pile, and the specific technical scheme is as follows:
a multi-working-condition simulation combination device for foundation pile low-strain detection comprises a cylindrical simulation pile, wherein a shading bag or a shading pipe is sleeved outside the simulation pile, the simulation pile comprises at least one first pile body, a first threaded column is arranged at the head end of the first pile body, and a first screw hole matched with the first threaded column is arranged at the tail end of the first pile body; the simulation pile further comprises a male end socket and a female end socket, the male end socket comprises a cylindrical first column body, and a second threaded column matched with the first screw hole is arranged at the head end of the first column body; the cylindrical second column body of female head, the tail end of second column body is provided with the second screw with first screw post assorted.
As an improvement of the technical scheme, the annular groove is arranged on the periphery of the simulation rod and used for simulating the defect of impedance reduction.
As the improvement of the technical scheme, a round pipe is sleeved outside the simulation pile and used for simulating the defect of impedance enlargement, namely diameter expansion, and a first opening seam is arranged on the side wall of the round pipe along the axial direction of the round pipe and used for releasing tension so as to facilitate mounting of the lantern ring.
As an improvement of the above technical solution, the side wall of the first pile body is provided with a through hole simulating pile defect.
As an improvement of the technical scheme, a round table-shaped sleeve is sleeved outside the simulation pile and used for simulating gradual change of impedance, a through hole matched with the first pile body is formed in the center of the sleeve, and a second opening seam is formed in the side wall of the sleeve along the axial direction of the sleeve.
As an improvement of the above technical scheme, the simulation pile further comprises a cylindrical second pile body and a cylindrical elastic rod, wherein the outer diameter of the second pile body is equal to the diameter of the first pile body, a third threaded column matched with the second screw hole is arranged at the head end of the second pile body, a blind hole matched with the elastic rod is arranged at the tail end of the second pile body, and the blind hole is of a circular hole-shaped structure; the tail end of the elastic rod is provided with a fourth screw hole matched with the first threaded column, and the improvement is used for simulating the change of the internal impedance of the pile.
As an improvement of the technical scheme, the elastic rod is arranged in the blind hole, and a cavity is arranged between the head end of the elastic rod and the bottom of the blind hole.
As an improvement of the technical scheme, the elastic rod is arranged in the blind hole, and the head end of the elastic rod abuts against the bottom of the blind hole.
As an improvement of the technical scheme, the first pile body, the male end socket, the female end socket, the circular tube, the sleeve and the second pile body are all made of polytetrafluoroethylene, and the elastic rod is made of polyethylene.
As an improvement of the technical scheme, grease is filled in the mounting gap on the surface of the simulation pile to form a grease coating.
The invention has the beneficial effects that:
the multi-working-condition simulation combination device for the low-strain detection of the foundation pile has the advantages of small occupied area, simplicity and convenience in installation and disassembly, low cost and small limitation of a site; after random combination is carried out, the simulated defect samples are large in quantity, the simulated defect types are large in quantity, and the set defect problem teachers or interview teachers can change randomly, so that the true level of examinees can be effectively reflected, and the implementation effect is good.
Drawings
FIG. 1 is a schematic structural diagram of a multi-condition simulation combination device for low strain detection of a foundation pile according to the present invention;
FIG. 2 is a schematic structural view of a dummy pile according to example 2;
fig. 3 is a schematic structural view of a first pile body in embodiment 2;
fig. 4 is a schematic structural view of the male end socket of the present invention;
FIG. 5 is a schematic structural view of the female end socket of the present invention;
FIG. 6 is a schematic structural view of a simulation pile in example 3;
FIG. 7 is a schematic structural view of a simulation pile according to embodiments 4 and 5;
FIG. 8 is a schematic structural view of the round tube of the present invention;
FIG. 9 is a schematic structural view of a simulation pile according to embodiments 6 and 7;
fig. 10 is a schematic structural view of a second pile body according to the present invention;
FIG. 11 is a schematic view of the structure of the elastic bar according to the present invention;
FIG. 12 is an internal schematic view of a kit according to the present invention;
FIG. 13 is a schematic structural view (side view) of the kit according to the present invention;
FIG. 14 is a schematic structural view of a dummy pile according to example 8;
FIG. 15 is a schematic structural view of a dummy pile according to example 9;
FIG. 16 is a schematic view of a ZZ-type cylindrical pile in example 11;
FIG. 17 is a schematic view of a MNGJ-ZZ simulation column in example 11;
FIG. 18 is a schematic view of a MN-ZZJY type dummy pile according to example 11;
FIG. 19 is a schematic representation of ZZ-XBCSJ # cylindrical studs of example 12;
FIG. 20 is a schematic view of a simulation pile No. MN-XBSJ in example 12;
FIG. 21 is a schematic view of a simulation pile of MN-XBSJJY type according to embodiment 12;
FIG. 22 is a waveform showing the test conducted on ZZ-type cylindrical pile in example 11;
FIG. 23 is a waveform of the test of the MNGJ-ZZ simulation column in example 11;
FIG. 24 is a waveform of the test of the MN-ZZJY type dummy post of example 11;
FIG. 25 is a waveform of a test conducted on ZZ-XBCSJ # cylindrical piles in example 12;
FIG. 26 is a waveform showing the test of the simulation pile No. MN-XBSJ in example 12;
FIG. 27 is a waveform of the test of the simulation post of MN-XBSJJY of example 12.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Example 1
As shown in fig. 1, the multi-condition simulation combination device for foundation pile low-strain detection includes a cylindrical simulation pile 10, a light shielding bag 20 is sleeved outside the simulation pile 10, the light shielding bag 20 is preferably a black cloth bag, and the light shielding bag 20 is used for shielding the simulation pile 10 to avoid the defect that the design around the simulation pile 10 is directly observed by a subject. In this case, instead of the light-shielding bag 20, a light-shielding tube can also be used, which is sheathed outside the dummy pile 10.
The sensor 30 is installed on the top of the simulation pile 10, the top of the shading bag 20 is provided with an installation hole for the simulation pile 10 to pass through, and the shading bag 20 and the simulation pile 10 are bound and fixed. The bottom of the dummy pile 10 is installed on the ground. The sensor 30 is a low-frequency sensor, an acceleration sensor, or a wide-band velocity sensor, which are commonly used in the conventional low-strain reflected wave method and have good low-frequency performance.
Example 2
The simulation pile 10 of the present embodiment simulating a complete structure, as shown in fig. 2 to 5, the simulation pile 10 includes at least one first pile body 11, an outer periphery of the first pile body 11 is a cylindrical structure, a first threaded column 111 protruding outward is disposed at a head end of the first pile body 11, a maximum diameter of the first threaded column 111 is smaller than a diameter of the first pile body 11, and a first screw hole 112 matching with the first threaded column 111 is disposed at a tail end of the first pile body 11; the simulation pile 10 further comprises a male end socket 12 and a female end socket 13, wherein the male end socket 12 comprises a cylindrical first column 121, the diameter of the first column 121 is equal to that of the first pile body 11, and a second threaded column 122 matched with the first screw hole 112 is arranged at the head end of the first column 121; the cylindrical second column 131 of female head 13, the diameter of second column 131 equals the diameter of first pile 11, the tail end of second column 131 is provided with the second screw hole 132 with first screw post 111 assorted.
The length of the first pile body 11 can be set to 440 and 480mm, and the diameter is 60 mm; the hole depth of the first screw hole 112 is 20mm, the length of the first threaded column 111 is 20mm, and the first threaded column 111 can fill the first screw hole 112; the second threaded hole 132 has a hole depth of 20mm, and the first threaded post 111 can fill the second threaded hole 132.
The two first pile bodies 11 are connected up and down, a first threaded column 111 of the first pile body 11 is in threaded connection with a first threaded hole 112 of the first pile body 11, a second threaded hole 132 of the first pile body 11 is in threaded connection with a second threaded column 122 of the male end socket 12, a first column 121 of the male end socket 12 is fixedly connected with the ground, for example, the first column is fixed by glue, and a second threaded hole 132 of the female end socket 13 is in threaded connection with the first threaded column 111 of the second pile body 11; in this way, the male end socket 12, the female end socket 13 and the two first pile bodies 11 are connected to form a cylindrical simulation pile 10, as shown in fig. 2. Wherein, the sensor 30 can be fixedly arranged at the female end socket 13.
In order to eliminate the influence of the bulges or hole structures at two ends of the two first pile bodies 11 after being assembled into a whole on a test signal, the testing device is provided with a male seal head 12 and a female seal head 13. Meanwhile, the male seal head 12 is fixed on the ground and is connected by threads, so that the first pile body 11 can be conveniently replaced at any time in the follow-up process.
Example 3
As shown in fig. 6, the outer periphery of first pile 11 is provided with an annular groove 113 having a circular ring structure along the outer periphery of first pile 11. The annular groove 113 is used to simulate the presence of a "necking" defect at the first pile 11.
In this embodiment, two first piles 11 with "necking" defects, i.e. two first piles 11 provided with annular grooves 113, are connected to form a simulated pile 10 with two "necking" defects, as shown in fig. 6.
Example 4
As shown in fig. 7 and 8, the outer sleeve of the dummy pile 10 is provided with a round tube 14, and the side wall of the round tube 14 is provided with a first open seam 141 along the axial direction of the round tube 14. The first open seam 141 is communicated with the inner cavity of the round tube 14. The existence of the round tube 14 is used for simulating the existence of the diameter expansion defect of the simulation pile 10, the round tube 14 is made of polytetrafluoroethylene, and the elasticity of the round tube 14 can enable the round tube 14 to be clamped outside the simulation pile 10; further, transparent adhesive tape may be used for reinforcement so that the circular tube 14 is fixed. The presence of the first open seam 141 facilitates movement of the tubular tube 14 to a different position outside the mock pile 10.
Example 5
As shown in fig. 7, a through hole 114 is provided in a side wall of the first pile body 11. The through hole 114 is circular, and the existence of the through hole 114 is used for simulating the existence of a 'hollow' defect in the simulation pile 10.
Example 6
As shown in fig. 9, 12 and 13, a circular truncated cone-shaped sleeve 15 is sleeved outside the dummy pile 10, a through hole 151 matched with the first pile body 11 is formed in the center of the sleeve 15, and a second opening slit 152 is formed in the side wall of the sleeve 15 along the axial direction of the sleeve 15. The second open seam 152 communicates with the through hole 151.
The sleeve 15 is used for simulating the existence of the ' tapered diameter ' defect of the simulation pile 10, the sleeve 15 is made of polytetrafluoroethylene, and the elasticity of the sleeve 15 can enable the sleeve 15 to be clamped ' outside the simulation pile 10; further, a transparent adhesive tape may be wound for reinforcement so that the set 15 is fixed. The presence of the second open seam 152 facilitates movement of the sleeve 15 to enable it to be located at different positions outside the mock pile 10.
Example 7
As shown in fig. 9, 10 and 11, the simulation pile 10 further includes a cylindrical second pile 16 and a cylindrical elastic rod 17, an outer diameter of the second pile 16 is equal to a diameter of the first pile 11, a third threaded post 161 matching with the second threaded hole 132 is disposed at a head end of the second pile 16, a blind hole 162 matching with the elastic rod 17 is disposed at a tail end of the second pile 16, and the blind hole 162 is a circular hole-shaped structure; the tail end of the elastic rod 17 is provided with a fourth screw hole 171 matched with the first threaded column 111.
The density of the elastic rod 17 is lower than that of the second pile 16, and the elastic rod can be made of PA66 (nylon) material. In this embodiment, the elastic rod 17 is disposed inside the blind hole 162, and the head end of the elastic rod 17 abuts against the bottom of the blind hole 162. The elastic bars 17 are located in areas intended to simulate the presence of "low intensity zones" defects. The simulated pile 10 of fig. 9 has a "taper" defect, a "neck" defect, and a "low strength zone" defect.
Example 8
As shown in fig. 14, the elastic rod 17 is disposed inside the blind hole 162, and a cavity 163 is disposed between a head end of the elastic rod 17 and a bottom of the blind hole 162. The existence of the cavity 163 is used for simulating the existence of a 'pile core cavity' defect at the position of the simulation pile 10.
In fig. 14, a simulated pile 10 has a diameter expansion defect, a low-strength area defect and a pile core cavity defect.
Example 9
As shown in fig. 15, the simulated pile 10 in fig. 15 has a "reduced diameter" defect, a "necking" defect, a "low strength zone" defect, a "pile core cavity" defect, and a "diameter expansion" defect.
Example 10
And filling butter into the mounting gap on the surface of the simulation pile 10 to form a butter coating, wherein the surface of the butter coating is arranged on the same plane as the surface of the simulation pile 10. The installation gaps on the surface of the simulation pile 10 are as follows: for example, a mounting gap between two first piles 11, a mounting gap between the first pile 11 and the second pile 16, a mounting gap between the first pile 11 and the male end enclosure 12 or the female end enclosure 13, and a mounting gap between the second pile 16 and the male end enclosure 12 or the female end enclosure 13.
The first pile body 11, the male end socket 12, the female end socket 13, the circular tube 14, the sleeve 15 and the second pile body 16 are all made of polytetrafluoroethylene, and the elastic rod 17 is made of polyethylene. The density of the polytetrafluoroethylene material is greater than that of nylon, and the polytetrafluoroethylene material is suitable for thread processing.
Example 11
Simulated contrast test for defect free
FIG. 16 is a complete defect-free cylindrical pile of PTFE construction with no gaps in the surface for simulating a concrete simulation pile in a prior art test; the number of the cylindrical pile is ZZ, so that for convenience of subsequent description, the cylindrical pile in FIG. 16 is abbreviated as ZZ-numbered cylindrical pile, and the subsequent naming rules are analogized in the same way; the height of ZZ cylindrical pile is 1000mm, and the diameter is 60 mm. The waveform of the ZZ-type cylindrical pile measured by the low-strain reflection method is shown in FIG. 22.
Fig. 17 shows a simulation pile 10 according to the present invention, the simulation pile 10 is assembled by two first pile bodies 11, male end sockets 12 and female end sockets 13, the surface of the first pile body 11 is free of defects, the simulation pile 10 is numbered again for convenience of explanation, and is abbreviated as MNGJ-ZZ simulation pile, the mounting gap on the surface of the MNGJ-ZZ simulation pile is not filled with grease, and the diameter of the MNGJ-ZZ simulation pile is 60 mm. Fig. 23 shows waveforms of the MNGJ-ZZ type simulation piles measured by the low strain reflection method.
Fig. 18 shows a simulation pile 10 according to the present invention, the simulation pile 10 is assembled by two first pile bodies 11, male end sockets 12 and female end sockets 13, the surface of the first pile body 11 is free of defects, the simulation pile 10 is numbered again for convenience of description, and is referred to as MN-ZZJY simulation pile for short, grease is filled in a mounting gap on the surface of the MN-ZZJY simulation pile, and the diameter of the MN-ZZJY simulation pile is 60 mm. The oscillogram of the MN-ZZJY simulation pile tested by the low-strain reflection method is shown in FIG. 24.
The ZZ-type cylindrical pile is different from the MNGJ-ZZ-type simulation pile in that: the MNGJ-ZZ simulation pile is assembled, a mounting gap exists on the surface of the MNGJ-ZZ simulation pile, and a mounting gap does not exist on the surface of the ZZ cylindrical pile. The difference between the MNGJ-ZZ simulation pile and the MN-ZZJY simulation pile is as follows: and filling grease into the mounting gap on the surface of the MNGJ-ZZ simulation pile to obtain the MN-ZZJY simulation pile. By comparison, it can be seen that:
firstly, the simulation pile assembled by the invention can test the waveform characteristics of a complete cylindrical pile (used for simulating the cylindrical concrete simulation pile in the existing test) by testing the waveform, the signal reflection at the bottom of the pile is obvious, and the wave velocity value is normal.
Secondly, shallow part reverse reflection signal superposition is carried out on the upper part of the curve of the assembled simulation pile (the installation gap is not filled with butter), so that the front section of the test waveform moves upwards, and the situation that a small amount of reflection signals are superposed at the threaded connection position is shown.
Thirdly, the test curve MN-ZZJY after the assembled simulation pile (the mounting gap is filled with butter) is highly matched with the complete ZZ-type cylindrical pile in the curve, the waveform characteristics are consistent, and the reflection signals of the pile top and the pile bottom are consistent.
Fourthly, from reflected stress waves calculated by the test waveforms of the complete cylindrical pile and the assembled simulation pile, the wave velocity of the complete cylindrical pile is 900 m/s; the wave speed of the assembled simulation pile is 880m/s, the wave speed of the assembled simulation pile is close to that of the assembled simulation pile, and the slightly low wave speed of the assembled simulation pile is caused by slight change of wave impedance at a joint.
Fifthly, the feature height of the test waveform of the assembled simulation pile (the installation gap is filled with grease) is consistent with that of the test waveform of the complete simulation rod, which indicates that the assembled simulation pile needs to be connected with grease under the accurate simulation condition; if the simulation pile has local defects, the test result is not greatly influenced by not filling the grease.
Example 12
Defect simulation contrast test
FIG. 19 is a cylindrical pile with a "necking" defect, made of PTFE and having no mounting gap on its surface, used to simulate a concrete dummy pile with a "necking" defect in the prior art test; the number of the cylindrical pile is ZZ-XBCSJ, and for convenience of subsequent description, the cylindrical pile in FIG. 19 is abbreviated as ZZ-XBCSJ cylindrical pile, and the subsequent naming rules are analogized in the same way; the ZZ-XBCSJ number cylindrical pile has the height of 1000mm and the diameter of 60 mm. The waveform of the ZZ-XBCSJ cylindrical pile tested by the low strain reflection method is shown in FIG. 25.
Fig. 20 shows a simulation pile 10 according to the present invention, the simulation pile 10 is assembled by two first pile bodies 11, male end sockets 12 and female end sockets 13, one of the first pile bodies 11 has no defect on the surface, and the other first pile body 11 has an annular groove 113 (simulating "necking" defect), the simulation pile 10 is numbered again for convenience of description, and is referred to as MN-XBSJ simulation pile for short, no grease is filled in the mounting gap on the surface of the MN-XBSJ simulation pile, and the diameter of the MN-XBSJ simulation pile is 60 mm. Fig. 26 shows a waveform diagram of the MN-XBSJ simulation pile tested by the low-strain reflection method.
Fig. 21 shows a simulation pile 10 according to the present invention, the simulation pile 10 is assembled by two first pile bodies 11, a male end socket 12 and a female end socket 13, wherein one first pile body 11 has no defect on the surface, and the other first pile body 11 has an annular groove 113 (simulating "necking" defect), the simulation pile 10 is numbered again for convenience of description, and is referred to as MN-XBSJJY simulation pile for short, the mounting gap on the surface of the MN-xbsjy simulation pile is filled with grease, and the diameter of the MN-XBSJJY simulation pile is 60 mm. The oscillogram of the MN-XBSJJY simulation pile tested by adopting the low-strain reflection wave method is shown in FIG. 27.
The difference between the ZZ-XBCSJ number cylindrical pile and the MN-XBSJ number simulation pile is as follows: the MN-XBSJ simulation pile is assembled, a mounting gap exists on the surface of the MN-XBSJ simulation pile, and a mounting gap does not exist on the surface of the ZZ-XBCSJ cylindrical pile. The difference between the MN-XBSJ simulation pile and the MN-XBSJJY simulation pile is as follows: and filling grease into the mounting gap on the surface of the MN-XBSJ simulation pile to obtain the MN-XBSJJY simulation pile. By comparison, it can be seen that:
firstly, the test waveform of the assembled defective simulation pile under the same working condition is consistent with the waveform characteristics measured by the defective cylindrical pile under the same working condition, and the gravitational wave signal reflection of the pile bottom and the defective part is consistent.
Secondly, the test waveform of the assembled defective simulation pile (the installation gap is not filled with butter) under the same working condition and the waveform measured by the defective cylindrical pile under the same working condition are superposed by shallow reverse reflection signals on the upper part of the curve, so that the front section of the test waveform moves upwards, and the condition that a small amount of reflection signals are superposed at the threaded connection position is indicated.
And thirdly, the test waveform height of the MN-XBSJ simulation piles (the installation gaps are not filled with butter) is consistent with that of the MN-XBSJJY simulation piles (the installation gaps are filled with butter), and the characteristics of pile tops, defects and pile bottom reflection signals are consistent.
Fourthly, the wave velocity of the assembled simulation pile is slightly low due to the fine change of the wave impedance at the joint.
In the embodiments, the invention only exemplifies several classic defects and defect combinations, and the specific application scenario of the multi-condition simulation combination device for detecting low strain of foundation piles is not limited to the embodiments. The simulation pile 10 can adopt 1 non-defective first pile body 11 to match with other first pile bodies 11 with at least one defect, or two first pile bodies 11 with at least one defect are combined, or the first pile body 11 and the second pile body 16 are combined. The necking defect is a necking defect which is common in the detection of a simulated foundation pile and exists in a pile body, the pile core cavity defect of the simulated pile 10 is an internal cavity defect which is common in the detection of the simulated foundation pile, and the low-strength area defect of the simulated pile 10 is a waveform reflection condition of a low-strength concrete area which is common in the detection of the simulated foundation pile and exists in the pile body; the outer sleeve of simulation stake 10 is equipped with pipe 14 for the working condition that the section that the pile body existed enlarges in the simulation foundation pile detection. The round table-shaped sleeve 15 is sleeved outside the simulation pile 10 and used for simulating the working condition that the section of the pile body changes gradually in the pile body detection.
By way of comparison of examples 11 and 12, the following conclusions can be drawn:
firstly, the low strain defect reflected wave is assembled and simulated by utilizing the multi-working condition simulation combination device, which is feasible and effective.
Secondly, the defect that obvious wave impedance reflection exists in the pile can be measured even if the assembled simulation pile is connected without adding butter. The reason is that: because the threaded connection is adopted, and the butt joint surface is made of elastic materials such as polytetrafluoroethylene and nylon, the downward transmission of stress waves is not influenced after the connection, so that the influence on the defect detection of the defect part is small.
And thirdly, for more accurately testing the shallow defect, the testing precision can be improved by filling grease in the mounting gap of the simulation pile, and the measured reflection waveform of the stress wave is basically consistent with the height of the joint-free complete cylindrical pile.
2 first pile bodies 11 or one first pile body 11 are combined to be matched with a second pile body 16, finally a male seal head 12 and a female seal head 13 are connected through threads, parts such as a circular tube 14, a kit 15 and an elastic rod 17 are additionally arranged according to the actual conditions, theoretically, simulation working condition conditions of N (hundreds of or even hundreds of) foundation pile defects can be combined, reflection wave simulation of the defects such as shrinkage, cavity, segregation, diameter expansion, gradual change of the pile body, local low-strength concrete area of the pile body, excessive thickness of the formed slag at the pile end and the like in common pile body detection can be effectively simulated at low cost, and after the reflection wave simulation is used, the reflection wave simulation can be easily disassembled and boxed so as to be reused next time; the multi-working-condition simulation combination device for the foundation pile low-strain detection is an auxiliary device for simulating the foundation pile low-strain detection defect test waveform, which is practical, economical, reasonable in design and efficient to assemble. Compared with the defects of a pile core cavity, an internal low-strength concrete area and the like actually manufactured in a limited field at present, the concrete pile with the defects of the pile core cavity, the internal low-strength concrete area and the like is troublesome to manufacture and has high construction requirements; the invention adopts an assembly method, the operation is simple, the first pile body 11, the male end socket 12, the female end socket 13, the circular tube 14, the sleeve member 15, the second pile body 16, the elastic rod 17 and other accessories are simple to manufacture, the installation and the operation are convenient, and the implementation effect is good.
The multi-working-condition simulation combination device for the low-strain detection of the foundation pile has the advantages of small floor area, simple and convenient installation, low cost and small limitation of a field, and can be installed in a detection mechanism or a training mechanism office place; after random combination is carried out, the simulated defect samples are large in quantity, the simulated defect types and the simulated defect positions are large in quantity, and the set defect question giving teachers or interview teachers can change randomly, so that the follow-up examinees can be effectively prevented from cheating through examinations by the answers of the prior examinees, the knowledge levels of the examinees can be truly and effectively reflected, and the implementation effect is good. In addition, the first pile body 11, the male end socket 12, the female end socket 13, the circular tube 14, the sleeve 15, the second pile body 16, the elastic rod 17 and other accessories can be reused, and the cost is further reduced; when not taking an examination, can dismantle and put into the containing box and case, effectively reduce area.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (10)
1. The utility model provides a foundation pile low strain detects uses multiplex condition simulation composite set, includes cylindric simulation stake (10), its characterized in that: the light shielding bag (20) is sleeved outside the simulation pile (10), the simulation pile (10) comprises at least one first pile body (11), a first threaded column (111) is arranged at the head end of the first pile body (11), and a first screw hole (112) matched with the first threaded column (111) is arranged at the tail end of the first pile body (11); the simulation pile (10) further comprises a male seal head (12) and a female seal head (13), the male seal head (12) comprises a cylindrical first column body (121), and a second threaded column (122) matched with the first screw hole (112) is arranged at the head end of the first column body (121); female head (13) cylindric second cylinder (131), the tail end of second cylinder (131) is provided with second screw hole (132) with first screw post (111) assorted.
2. The multi-working-condition simulation combination device for foundation pile low-strain detection according to claim 1, characterized in that: an annular groove (113) is formed in the periphery of the first pile body (11).
3. The multi-working-condition simulation combination device for foundation pile low-strain detection according to claim 1, characterized in that: the outside cover of simulation stake (10) is equipped with pipe (14), the lateral wall of pipe (14) is provided with first opening seam (141) along pipe (14) axial.
4. The multi-working-condition simulation combination device for foundation pile low-strain detection according to claim 1, characterized in that: the side wall of the first pile body (11) is provided with a through hole (114).
5. The multi-working-condition simulation combination device for foundation pile low-strain detection according to claim 1, characterized in that: the outside cover of simulation stake (10) is equipped with round platform form external member (15), the central authorities of external member (15) are provided with first pile body (11) assorted through-hole (151), the lateral wall of external member (15) is provided with second opening seam (152) along external member (15) axial.
6. The multi-working-condition simulation combination device for foundation pile low-strain detection according to claim 1, characterized in that: the simulation pile (10) further comprises a cylindrical second pile body (16) and a cylindrical elastic rod (17), the outer diameter of the second pile body (16) is equal to the diameter of the first pile body (11), a third threaded column (161) matched with the second screw hole (132) is arranged at the head end of the second pile body (16), a blind hole (162) matched with the elastic rod (17) is arranged at the tail end of the second pile body (16), and the blind hole (162) is of a round hole structure; and the tail end of the elastic rod (17) is provided with a fourth screw hole (171) matched with the first threaded column (111).
7. The multi-working-condition simulation combination device for foundation pile low-strain detection according to claim 6, wherein: elastic rod (17) set up in the inside of blind hole (162), be provided with cavity (163) between the bottom of the head end of elastic rod (17) and blind hole (162).
8. The multi-working-condition simulation combination device for foundation pile low-strain detection according to claim 6, wherein: the elastic rod (17) is arranged inside the blind hole (162), and the head end of the elastic rod (17) abuts against the bottom of the blind hole (162).
9. The multi-working-condition simulation combination device for foundation pile low-strain detection according to claim 6, wherein: the first pile body (11), the male end socket (12), the female end socket (13), the round pipe (14), the sleeve piece (15) and the second pile body (16) are all made of polytetrafluoroethylene, and the elastic rod (17) is made of polyethylene.
10. The multi-working-condition simulation combination device for detecting the low strain of the foundation pile according to any one of claims 1 to 9, wherein: and filling butter into the mounting gap on the surface of the simulation pile (10) to form a butter coating.
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| CN111710226B (en) | 2024-08-27 |
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