CN110847257B - Pile foundation static load experiment device and method suitable for narrow space - Google Patents
Pile foundation static load experiment device and method suitable for narrow space Download PDFInfo
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- CN110847257B CN110847257B CN201911266700.4A CN201911266700A CN110847257B CN 110847257 B CN110847257 B CN 110847257B CN 201911266700 A CN201911266700 A CN 201911266700A CN 110847257 B CN110847257 B CN 110847257B
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Abstract
The invention discloses a pile foundation static load experimental device and a method suitable for a narrow space, wherein the pile foundation static load experimental device is arranged between a test pile on a foundation and a structural beam on a structural column, and comprises a loading device and a testing device connected with the loading device; the loading device comprises a supporting piece, a load column and a jack with a pressurizing device, the jack is arranged at the upper end of the test pile, the load column is arranged between the jack and the supporting piece, and the upper end of the supporting piece is abutted against the lower end face of the structural beam; the load column is formed by detachably fixing a plurality of steel sleeves; the testing device comprises a reference beam arranged on the side edge of the loading device, a displacement sensor arranged on the reference beam and a static load testing analyzer respectively connected with the pressurizing device and the displacement sensor. The invention has simple structure, is suitable for narrow space, is convenient for assembly and disassembly in the experimental process, and can be recycled.
Description
Technical Field
The invention belongs to the technical field of building construction, and particularly relates to a pile foundation static load experimental device suitable for a narrow space.
Background
After the construction of the pile foundation is completed, a static load test is required to test whether the ultimate bearing capacity of the pile foundation can meet the design requirement. Currently, the most common static load tests are the pile loading method and the anchor pile method. The pile loading method is that an experimental platform is erected in the center of a test pile, and a sand bag or a concrete block is stacked on the platform; the anchor pile method is to pour a counter-force beam before the test is started so as to provide counter-force.
For example, chinese patent publication No. CN104532884A discloses a method for testing static load and pressing pile of foundation pile by eccentric loading method outside buttress, which comprises placing a jack on the foundation pile, selecting a proper main beam to be placed on the jack, placing the buttress in a direction parallel to the main beam, placing secondary beams on the buttress, placing all the secondary beams on a uniform plane, uniformly and symmetrically placing, hoisting the loading material on the secondary beams, supplying oil to the jack, and performing static load test or pile pressing construction.
Chinese patent publication No. CN109518734A discloses an anchor pile method static load test detection device, which includes a static load test pile and a jack disposed above the static load test pile, wherein a main beam is horizontally disposed above the jack, at least two secondary beams perpendicular to the main beam are horizontally disposed above the main beam, two anchor piles are respectively disposed under each secondary beam, and the anchor piles are symmetrically disposed at two sides of the main beam; a plurality of anchor bars are arranged in the middle of the anchor pile, a row of parallel connecting rods are respectively arranged on two sides of the anchor pile, the connecting rods are positioned on two sides of the secondary beam, an anchor disc is arranged between the anchor pile and the main beam, a supporting piece is arranged between the anchor disc and the anchor pile, and the upper ends of the anchor bars are fixedly connected with the anchor disc; the upper end of the connecting rod passes through the anchor box and is fixed above the secondary beam through the reinforcing steel bar fixing piece.
However, for some projects with space requirements, such as underground layer-increasing transformation underpinning pile bearing capacity detection projects, the stowage rule is obviously not suitable. Although the anchor pile method is suitable for similar projects, the counter-force beam needs to be poured before the experiment, and after the experiment is finished, the counter-force beam needs to be chiseled off, so that the anchor pile method cannot be recycled. Therefore, the anchor pile method has problems of being uneconomical and having a long test time.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a pile foundation static load experimental device and method suitable for a narrow space, which are simple in structure and convenient to assemble and disassemble in the experimental process.
A pile foundation static load experimental device suitable for narrow space is arranged between a test pile and a structural beam, wherein the structural beam is fixed on a structural column and comprises a loading device and a testing device connected with the loading device;
the loading device comprises a supporting piece, a load column and a jack with a pressurizing device, the jack is placed at the upper end of the test pile, the load column is arranged between the jack and the supporting piece, and the upper end of the supporting piece is abutted against the lower end face of the structural beam; the load column is formed by detachably fixing a plurality of steel sleeves;
the testing device comprises a reference beam arranged on the side edge of the loading device, a displacement sensor arranged on the reference beam and a static load testing analyzer respectively connected with the pressurizing device and the displacement sensor.
In the invention, the supporting piece is of a T-shaped structure and comprises transverse ribbed steel and a vertical steel short column, and a steel pipe inclined strut is connected between the ribbed steel and the steel short column.
The loading device further comprises at least one right-angle steel hinge fixed on the structural column in a surrounding mode, wherein a horizontal steel plate is welded to the lower end of the lower-most right-angle steel hinge, and the free end of the steel plate is arranged between the supporting piece and the load column.
In order to facilitate field installation, the outer side of each steel sleeve is symmetrically provided with a handle.
And steel base plates and steel gaskets are arranged between the supporting piece and the load column, between the load column and the jack and between the jack and the test pile. The number of the steel backing plates and the steel gaskets can be adjusted, so that the requirements of different working spaces can be met.
The displacement sensor is fixed on the reference beam through the magnetic gauge stand.
The invention also provides a method for carrying out a static load experiment by using the pile foundation static load experiment device, which comprises the following steps:
(1) installing a loading device and a testing device according to actual conditions on site;
(2) loading a load: controlling a pressurizing device to carry out graded loading on the test pile, and after each grade of load is applied, measuring and reading the pile top settlement amount according to the steps of 5min, 15min, 30min, 45min and 60min respectively, and then measuring and reading the pile top settlement amount every 30 min; when the settlement rate of the pile top reaches a relatively stable standard, applying the next stage of load until reaching a loading termination standard;
(3) load unloading: unloading in a grading manner, wherein each unloading amount is 2 times of the grading load during loading, and the unloading is carried out in a grading manner in an equivalent manner step by step; during unloading, maintaining each level of load for 1h, and unloading the next level of load after measuring and reading the pile top settlement amount according to 15min, 30min and 60min respectively; and after unloading to zero, measuring and reading the residual settlement of the pile top.
In the step (2), the concrete step that the settlement rate of the pile top reaches the relative stability standard is as follows: the settlement of the pile top in every 1h is not more than 0.1 mm.
The termination loading condition comprises the following steps:
a. under the action of a certain level of load, the settlement of the pile top is 2 times greater than that under the action of the previous level of load, and the pile top does not reach the relatively stable standard of settlement after 24 hours;
b. the maximum loading value of the design requirement is reached and the pile top settlement reaches a relatively stable standard;
c. floor, structural columns or structural beams develop cracks.
In the load loading process, when a p-s curve displayed on a static load test analyzer is in a slow deformation type, the load can be loaded until the total settlement of the pile top reaches 60-80 mm.
Compared with the prior art, the invention has the following beneficial effects:
1. the static load experiment device is composed of simple components, can be assembled on site, can be disassembled after the experiment is finished, and can be transported to the next project, and has the advantages of simple structure, convenience in transportation and the like.
2. The static load experimental device can provide three parts of counter forces, wherein the first part is the friction force between the right-angle steel hinge and the structural column, the second part is the counter force provided by the structural beam and the floor slab, and the last part is the self-weight counter force of the concrete block. The counter force is applied step by step, and the counter forces of the first part and the second part are applied firstly; when the counter force of the two parts is insufficient, the concrete blocks can be stacked at the position right above the test pile area so as to provide enough counter force.
Drawings
Fig. 1 is a schematic view of the overall structure of a pile foundation static load experimental device suitable for a narrow space.
In the figure: concrete block 1, structural beam 2, floor 3, ribbed steel 4, steel short column 5, steel pipe bracing 6, steel backing plate 7, steel washer 8, steel sleeve 9, jack 10, reference beam 11, magnetism gauge stand 12, displacement sensor 13, test pile 14, pressure device 15, static load test analyzer 16, right angle steel hinge 17, structural column 18, steel sheet 19.
Detailed Description
The invention will be described in further detail below with reference to the drawings and examples, which are intended to facilitate the understanding of the invention without limiting it in any way.
As shown in figure 1, the static load experiment device for the pile foundation suitable for the narrow space is integrally arranged between a test pile 14 on a foundation and a structural beam 2 on a structural column 18, and comprises a loading device and a testing device connected with the loading device.
The loading device comprises a support member, a load column and a jack 10 with a pressurizing device 15, wherein the jack 10 is arranged at the upper end of the test pile 14. The load column is formed by detachably fixing a plurality of steel sleeves 9, and is arranged between a jack 10 and a support piece.
Support piece is T type structure, including horizontal ribbed steel 4 and vertical shaped steel short column 5, is connected with steel pipe bracing 6 between ribbed steel 4 and the shaped steel short column 5, and the installation is accomplished the back, and ribbed steel 4 offsets with the lower terminal surface of structural beam 2.
Two right angle steel hinges 17 are fixed on the structural column 18 in an encircling manner, wherein a horizontal steel plate 19 is welded at the lower end of the lower right angle steel hinge, and the free end of the steel plate 19 is arranged between the supporting piece and the load column. During installation, the steel short column 5 can be firstly placed on the steel plate 19 to complete primary fixing, and then the load column and the jack 10 are installed below the steel plate 19.
The testing device comprises a reference beam 11 arranged on the side of the loading device, a displacement sensor 13 arranged on the reference beam 11 and a static load testing analyzer 16 respectively connected with a pressurizing device 15 and the displacement sensor 13. The displacement sensor 13 is fixed to the reference beam 11 via a magnetic gauge stand 12.
In order to facilitate field installation, a handle is symmetrically arranged on the outer side of each steel sleeve 9.
The static load experimental device can provide three parts of counter forces, wherein the first part is the friction force between the right-angle steel hinge 17 and the structural column 18; the second part is the counterforce provided by the structural beam 2 and the floor slab 3; the last part is the self-weight reaction force of the concrete block 1. The counter force of the invention is applied step by step, the counter force of the first part and the second part is applied firstly; when the reaction force of the two parts is insufficient, the concrete block 1 can be stacked at a position right above the test pile area to provide sufficient reaction force. Meanwhile, whether cracks exist or not can be observed at the periphery of the floor slab 3 stacked on the upper layer, and a judgment standard is provided for finishing the experiment.
The static load experiment device provided by the invention is composed of simple components, can be assembled on site, and can be disassembled after the experiment is finished and transported to the next project. Wherein, the field assembly process is as follows:
s1, assembling right-angle steel hinges 17 at the tops of the structural columns 18;
s2, forming a support part of a T-shaped structure consisting of ribbed steel sections 4, a steel section short column 5 and a steel pipe inclined strut 6;
s3, placing the structure formed in the step S2 on the steel plate 19 of the right-angle steel hinge 17, and ensuring that the structure is on the same vertical line with the center of the test pile 14;
s4, placing a steel washer 8 above the test pile 14, placing a steel backing plate 7 above the steel washer 8, and placing a jack 10 above the steel backing plate 7;
s5, placing a steel backing plate 7 above the jack 10; a steel gasket 8 is arranged above the steel base plate 7; a steel sleeve 9 is arranged above the steel washer 8;
s6, placing a steel gasket 8 above the steel sleeve 9; placing a steel backing plate 7 above the steel washer 8, contacting the structure formed in the step S2, and enabling the steel backing plate to be on the same vertical line with the center of the test pile 14;
s7, assembling the jack 10 and the pressurizing device 15;
s8, assembling the reference beam 11, and erecting the magnetic gauge stand 12 on the reference beam 11;
s9, the displacement sensor 13 is fixed to the magnetic gauge stand 12, and the displacement sensor 13 and the pressure device 15 are connected to the static load test analyzer 16.
When the pile foundation static load experiment device is used for carrying out experiments, the pile foundation static load experiment device comprises a loading step, a loading termination step and an unloading step.
A loading step:
1. the loading is carried out in a grading way, and the step-by-step equivalent loading is adopted; the grading load is preferably 1/10 of the maximum loading value or the estimated limit bearing capacity, wherein the 1 st grade loading capacity can be 2 times of the grading load;
2. after each level of load is applied, measuring and reading the pile top settlement amount according to the time of 5min, 15min, 30min, 45min and 60min respectively, and measuring and reading the pile top settlement amount every 30min later;
3. and (3) testing the pile settlement relatively stable standard: the settlement of the pile top within every 1h is not more than 0.1 mm;
4. when the settlement rate of the pile top reaches a relatively stable standard, the next stage of load can be applied;
terminating the loading standard:
1. under the action of a certain stage of load, the settlement of the pile top is 5 times greater than that under the action of the previous stage of load, and the total settlement of the pile top exceeds 40 mm;
2. under the action of a certain level of load, the settlement of the pile top is 2 times greater than that under the action of the previous level of load, and the pile top does not reach the settlement relatively stable standard after 24 hours (item 3 of the loading step);
3. the maximum loading value of the design requirement is reached and the pile top settlement reaches a relatively stable standard (item 3 of the loading step);
4. floor, structural columns and beams have cracks;
when the p-s curve (load-sedimentation curve) is in slow deformation, the total sedimentation of the pile top can be loaded to 60-80 mm;
unloading:
1. unloading is carried out in a grading manner, the unloading capacity of each grade is 2 times of the grading load during loading, and the unloading is carried out in a grading manner step by step in an equivalent manner;
2. during unloading, each level of load is maintained for 1h, and the next level of load can be unloaded after the settlement of the pile top is measured and read according to the 15min, 30min and 60min respectively; and after the pile is unloaded to zero, measuring and reading the residual settlement of the pile top.
The embodiments described above are intended to illustrate the technical solutions and advantages of the present invention, and it should be understood that the above-mentioned embodiments are only specific embodiments of the present invention, and are not intended to limit the present invention, and any modifications, additions and equivalents made within the scope of the principles of the present invention should be included in the scope of the present invention.
Claims (9)
1. A method for carrying on the static load experiment, utilize the pile foundation static load experimental apparatus suitable for narrow and small space, it is installed between test pile and structural beam, the said structural beam is fixed on structural column, characterized by that, the pile foundation static load experimental apparatus includes the loading device and testing arrangement in connection with loading device;
the loading device comprises a supporting piece, a load column and a jack with a pressurizing device, the jack is placed at the upper end of the test pile, the load column is arranged between the jack and the supporting piece, and the upper end of the supporting piece is abutted against the lower end face of the structural beam; the load column is formed by detachably fixing a plurality of steel sleeves;
the test device comprises a reference beam arranged on the side edge of the loading device, a displacement sensor arranged on the reference beam and a static load test analyzer respectively connected with the pressurizing device and the displacement sensor;
the static load test comprises the following steps:
(1) installing a loading device and a testing device according to actual conditions on site;
(2) loading a load: controlling a pressurizing device to carry out graded loading on the test pile, and after each grade of load is applied, measuring and reading the pile top settlement amount according to the steps of 5min, 15min, 30min, 45min and 60min respectively, and then measuring and reading the pile top settlement amount every 30 min; when the settlement rate of the pile top reaches a relatively stable standard, applying the next stage of load until reaching a loading termination standard;
(3) load unloading: unloading in a grading manner, wherein each unloading amount is 2 times of the grading load during loading, and the unloading is carried out in a grading manner in an equivalent manner step by step; during unloading, maintaining each level of load for 1h, and unloading the next level of load after measuring and reading the pile top settlement amount according to 15min, 30min and 60min respectively; and after unloading to zero, measuring and reading the residual settlement of the pile top.
2. The method of claim 1, wherein the support member is a T-shaped structure comprising a transverse ribbed steel bar and a vertical steel bar stub, and a steel tube brace is connected between the ribbed steel bar and the steel bar stub.
3. The method of claim 1, wherein the loading unit further comprises at least one right angle steel hinge fastened around the structural column, wherein a horizontal steel plate is welded to the lower end of the lowermost right angle steel hinge, and the free end of the steel plate is disposed between the support member and the load column.
4. The method for carrying out the static load test according to claim 1, wherein a pull handle is symmetrically arranged on the outer side of each steel sleeve.
5. The method of claim 1, wherein steel backing plates and steel washers are disposed between the support member and the load column, between the load column and the jack, and between the jack and the test pile.
6. The method of claim 1, wherein the displacement sensor is fixed to the reference beam by a magnetic gauge stand.
7. The method for carrying out the static load test according to claim 1, wherein in the step (2), the pile top settlement rate reaching the relative stability standard is specifically as follows: the settlement of the pile top in every 1h is not more than 0.1 mm.
8. The method for performing a static load test as claimed in claim 1, wherein in step (2), said end-loading condition comprises:
a. under the action of a certain level of load, the settlement of the pile top is 2 times greater than that under the action of the previous level of load, and the pile top does not reach the relatively stable standard of settlement after 24 hours;
b. the maximum loading value of the design requirement is reached and the pile top settlement reaches a relatively stable standard;
c. floor, structural columns or structural beams develop cracks.
9. The method of claim 8, wherein the total settling amount of the pile top is 60-80mm when the p-s curve displayed on the static load test analyzer is in a gradual change form during the loading process.
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| CN111549830B (en) * | 2020-03-24 | 2021-08-06 | 北京城建设计发展集团股份有限公司 | Vertical uplift static load test method for uplift pile single pile of subway open cut station |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH01116424A (en) * | 1987-10-30 | 1989-05-09 | Chiyoda Corp | Method and apparatus for loading test of pile |
| CN206110202U (en) * | 2016-10-25 | 2017-04-19 | 青岛海智检测科技有限公司 | Pile foundation static load detection device |
| CN110004998A (en) * | 2019-05-14 | 2019-07-12 | 中国五冶集团有限公司 | A kind of bored concrete pile test pile apparatus and its pile testing method |
| CN211596858U (en) * | 2019-12-11 | 2020-09-29 | 台州学院 | Pile foundation static load experimental device suitable for narrow space |
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2019
- 2019-12-11 CN CN201911266700.4A patent/CN110847257B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH01116424A (en) * | 1987-10-30 | 1989-05-09 | Chiyoda Corp | Method and apparatus for loading test of pile |
| CN206110202U (en) * | 2016-10-25 | 2017-04-19 | 青岛海智检测科技有限公司 | Pile foundation static load detection device |
| CN110004998A (en) * | 2019-05-14 | 2019-07-12 | 中国五冶集团有限公司 | A kind of bored concrete pile test pile apparatus and its pile testing method |
| CN211596858U (en) * | 2019-12-11 | 2020-09-29 | 台州学院 | Pile foundation static load experimental device suitable for narrow space |
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