CN112160349A - Full-life-cycle geotechnical centrifuge test device for driven pile and operation method thereof - Google Patents
Full-life-cycle geotechnical centrifuge test device for driven pile and operation method thereof Download PDFInfo
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- CN112160349A CN112160349A CN202010902475.5A CN202010902475A CN112160349A CN 112160349 A CN112160349 A CN 112160349A CN 202010902475 A CN202010902475 A CN 202010902475A CN 112160349 A CN112160349 A CN 112160349A
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D33/00—Testing foundations or foundation structures
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D5/00—Bulkheads, piles, or other structural elements specially adapted to foundation engineering
- E02D5/22—Piles
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D7/00—Methods or apparatus for placing sheet pile bulkheads, piles, mouldpipes, or other moulds
- E02D7/02—Placing by driving
- E02D7/06—Power-driven drivers
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D7/00—Methods or apparatus for placing sheet pile bulkheads, piles, mouldpipes, or other moulds
- E02D7/02—Placing by driving
- E02D7/06—Power-driven drivers
- E02D7/14—Components for drivers inasmuch as not specially for a specific driver construction
- E02D7/16—Scaffolds or supports for drivers
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Abstract
The invention discloses a driven pile full-life-cycle geotechnical centrifuge test device which comprises a supporting system, a driven pile full-life loading system, a pile-soil system, a centrifuge system and a measurement and acquisition system. The invention also provides an operation method of the soil engineering centrifuge test device for the whole life cycle of the driven pile. The invention can carry out the geotechnical centrifuge test of the interaction of the pile and the soil in the whole life cycle of the driven pile, provides an effective test device and method for the research of the mutual dynamic response of the pile and the soil in the whole life of the driven pile in the penetration of different installation modes and the extraction geotechnical centrifuge test of different extraction modes, can visually observe the deformation characteristics of the pile and the soil in the whole life process by a high-speed video camera or a digital camera, and can carry out related tests in stages.
Description
Technical Field
The invention relates to a full-life-cycle geotechnical centrifuge test device for a driven pile. The invention also relates to an operation method of the full-life-cycle geotechnical centrifuge test device for the driven pile.
Background
At present, research on the whole life cycle bearing performance of a pile mainly focuses on pile-soil response during operation, however, for a driven pile, physical and mechanical parameters of pile-soil around the pile, such as hole pressure, in the driving process have a significant influence on the effective stress state of the pile-soil around the pile during service operation, and for part of pile foundations, such as offshore wind power pile foundations, the service life of the pile foundations is generally 20-50 years, and the pile-soil response during service needs to be pulled out after the service life is completed, so that the influence of the pile-soil response during service life on pulling-out operation needs to be developed. Therefore, the development of the pile-soil response of the full life of the driven pile from penetration installation, service operation and retirement extraction is beneficial to analyzing the development and evolution research on the bearing performance of the pile, optimizing the size design of the pile and the like. However, currently, there is no relevant analysis means, the field test research of the full life is almost unrealistic due to extremely high cost, the numerical technology and the theoretical method have limitations and cannot realize the continuous research of the full life, and the existing indoor test cannot perform fine analysis of pile-soil interaction due to the influence of the size effect.
Disclosure of Invention
The invention aims to solve the technical problem of providing a full-life-cycle geotechnical centrifuge test device for a driven pile, which can test and research the full-life-cycle bearing performance of the pile and obtain more accurate data and more visual image data by means of improvement of equipment. The technical problem to be solved by the invention is also to provide an operation method of the soil engineering centrifuge test device for the full life cycle of the driven pile.
Therefore, the invention provides a full-life cycle geotechnical centrifuge test device for a driven pile, which is characterized in that: the pile-driving full-life loading system comprises a supporting system, a pile-driving full-life loading system, a pile-soil system, a centrifugal machine system and a measuring and collecting system;
a support system: the vertical support system mainly comprises a threaded rigid column, a vertical outer support frame, a vertical inner support frame and a bottom rigid plate, the vertical support system is used for supporting the whole test model and is connected with a corresponding device of a centrifugal machine, and meanwhile, a support platform is provided for the pile driving frame in the model, and the vertical outer support frame is movably connected with the threaded rigid column and is controlled to lift through a vertical support lifting motor;
pile driving full-life loading system: the pile driving device comprises a pile driving frame, pile driving equipment and a horizontal loading system, wherein the pile driving frame supporting system is connected with a vertical supporting system, a scale is marked on the pile driving frame, the pile driving equipment comprises a pile driving hammer guide rail, a pile driving guide rail and vertical loading equipment, a pile driving hammer pad is arranged at the lower part of the vertical loading equipment, and the horizontal loading system simulates pile soil response of the action of combined load during the service period of a pile; adjusting the loading mode of the vertical loading equipment through a servo and a computer;
pile soil system: the device comprises a model pile and a model box, wherein a pile cap is fixed on the pile top of the model pile, the pile cap protects the pile head of the model pile in the injection process, a monitoring element of physical and mechanical variables is adhered to the pile body, the model box is a semi-cylindrical box body with a closed lower part and an open upper part, the semi-circular part consists of a high-strength and high-rigidity steel plate, a drain hole is distributed on the box body, the semi-circular section of the model box consists of a high-strength resin transparent plate, a soil body is distributed in the model box, a lifting motor is fixed below a fixed support and is sleeved on a threaded rigid column, and the lifting motor drives a nut to rotate to realize lifting on the threaded rigid column and control the height of the fixed support;
a centrifuge system: the test device comprises a centrifuge, wherein a support system, a driven pile life-span loading system and a pile soil system are fixedly arranged in a test cabin of the centrifuge, the movement of the centrifuge is used for applying supergravity to a test model, the fluid-solid coupling time is accelerated in a supergravity environment, and the change process is accelerated;
the measurement system comprises: the pile body monitoring system comprises a pile body monitoring element, the pile body monitoring element tests the initial stress strain, the hole pressure state and the corresponding physical mechanical parameters in the piling process and after the pile is installed, and the pile body monitoring element collects the physical mechanical parameters such as the deformation stress of the pile body.
Preferably, the deformation characteristics of the pile-soil interaction during the piling process are photographed through the high-strength resin transparent plate by using a high-speed video camera or a high-speed digital camera.
Preferably, the pile driving frame supporting system is configured with an upper outer support of the pile driving frame, an upper inner support of the pile driving frame, a lower outer support of the pile driving frame, an upper back support of the pile driving frame, and a lower back support of the pile driving frame for supporting the pile driving frame, the upper outer support on the left side of the pile driving frame, the upper inner support on the pile driving frame, the lower inner support of the pile driving frame, and the lower outer support of the pile driving frame are all long rods, and the upper outer support on the right side, the upper inner support on the pile driving frame, the lower inner support of the pile driving frame, and the lower outer support of the pile driving frame are all short rods, so that the pile driving frame is away from the middle position.
Preferably, one end of the upper outer support of the pile driving frame is connected with the threaded rigid column, the other end of the upper outer support of the pile driving frame is connected with the upper end of the pile driving frame, one end of the lower outer support of the pile driving frame is connected with the threaded rigid column, the other end of the lower outer support of the pile driving frame is connected with the lower end of the pile driving frame, one end of the upper inner support of the pile driving frame is connected with the support system of the pile driving frame, the other end of the upper inner support of the pile driving frame is connected with the middle upper part of the pile driving frame, and one.
Preferably, the model box is provided with a fixed support, the inner side end of the fixed support is tightly pressed on the model box, the other end of the fixed support is fixed on a fixed support lifting motor, the fixed support lifting motor is provided with a nut which is sleeved with the threaded rigid column and moves up and down along the threaded rigid column through a driving nut; the vertical outer support frame is provided with a vertical support lifting motor, and a horizontal loading servo motor is fixed on the pile driving frame and transversely drives the model pile through a horizontal force transmission rigid rod.
The invention provides an operation method of the soil engineering centrifuge test device for the whole life cycle of the driven pile, which comprises the following steps:
determining the size and the arrangement position of each system according to the in-situ size and the magnitude of a geotechnical centrifuge;
secondly, determining the life-cycle loading cycle, thereby setting the loading mode of the loading equipment,
thirdly, installing a supporting system, a pile-soil system and a measuring system;
installing a driven pile life-cycle loading system, wherein the loading system is a centrifuge, the driven pile life-cycle geotechnical centrifuge test device is fixedly installed in a test cabin of the centrifuge, and all systems are debugged in place;
and fifthly, carrying out a geotechnical centrifuge test.
Preferably, the steps are specifically as follows:
firstly, determining the size and the arrangement of each system of the testing device: the test is to analyze the full-life cycle pile-soil response of a large-diameter open pile foundation in-situ saturated clay, the in-situ size of the pile is 8m in pile diameter, 80m in pile length, 9cm in wall thickness, the saturated clay is ocean saturated clay, the fluid is seawater, the installation mode adopts hammering penetration, and the extraction mode adopts static pressure; the size of the model pile is set to be 5.34cm in diameter, 53.34cm in pile length and 0.6mm in wall thickness; the pile body is uniformly and symmetrically provided with 10 grating optical fiber points on each side, the grating optical fiber soil pressure miniature boxes and osmometers in the soil body are respectively and symmetrically arranged in 3 rows, the two test elements are arranged at intervals in 12 rows, and each row is 8 along the height direction; the size of the model box is 1.5m in diameter and 1.0m in height, 10 grating fiber points are uniformly distributed on the drain holes along the height direction of the model box, 10 grating fiber points are uniformly distributed on the bottom along the diameter direction, and 15 rows of grating fiber soil pressure miniature boxes and osmometers are distributed along the arc direction; the length of the pile driving frame is 1.2m, the width of the pile driving frame is 0.25m, the pile driving hammer guide rail and the pile driving guide rail are uniformly and symmetrically vertically distributed on the pile driving frame, and the pile driving frame is symmetrically fixed in the vertical supporting system along the length direction;
determining a full-life loading cycle and setting a loading mode: adopting a penetration mode as hammering, wherein the pile bears the action of vertical static load and horizontal cyclic load on the upper part during service, the extraction mode is static load, different loading modes are selected according to different loads at different loading stages, corresponding vertical loading is selected, the horizontal loading mode and the vertical extraction mode are both servo-controlled, and the vertical loading device adopts hammering at the penetration installation stage; the pile pad is in static load in a service operation stage, and is fixed with the pile pad through automatic buckles or electromagnetic electrification magnetic force in a retired pulling-out stage so as to pull out the pile pad in the static load;
thirdly, installing a supporting system, a pile-soil system and a measuring system;
installing a driven pile life-cycle loading system, wherein the loading system is a centrifuge, the driven pile life-cycle geotechnical centrifuge test device is fixedly installed in a test cabin of the centrifuge, and all systems are debugged in place;
fifthly, carrying out a geotechnical centrifuge test: the geotechnical centrifuge has the loading gravity of 150g, a hammering penetration test is carried out after loading, monitoring data are collected through a wireless collection system, a hammering penetration process is recorded through a high-definition high-speed computer, and hammering penetration of a pile hammer is controlled through wireless servo control; secondly, after the penetration is completed, a long-term bearing performance test is carried out, a pile-soil interaction test of the pile under combined load is researched, after the duration of the test requirement, data are always kept in a collection state in the duration, servo control is converted into a pulling-out mode, a pulling-out test is carried out, relevant data are collected through a wireless collection system, the pulling-out process is recorded through a high-speed camera, and further the geotechnical centrifuge test research of the bearing characteristic of the whole service life is completed.
Preferably, the vertical loading equipment determines a loading mode according to which stage the pile is in the test process, the hammer, the vibration hammer and the static pressure hammer are selected in the penetration installation period, the hammer adopts a hydraulic hammer, the hydraulic hammer is driven in an electromagnetic impact mode, the static load mode is adopted in the service operation period, the pulling-out mode in the decommissioning pulling-out period can adopt vibration pulling-out and static load pulling-out, the pulling-out equipment adopts electromagnetic control, the magnetic force of the hammer pad can be changed and controlled through current, the pile cap, the pile pad, the hammer pad and the model pile are ensured to be fixed into a whole in the pulling-out process, and automatic clamping equipment is adopted for fixing.
The invention has the technical effects that:
1) according to the invention, the main body test device is fixedly combined with the centrifugal machine, the hypergravity environment is applied through the centrifugal machine, the fluid-solid coupling time is accelerated in the hypergravity environment, the change process is accelerated, and the physical and mechanical state of the soil body which is actually fluid-solid coupled is close to that of the soil body, so that the geotechnical centrifugal machine test of the interaction of the pile and the soil in the whole life cycle of the driven pile can be carried out;
2) observing the deformation characteristics of the pile soil in the whole life process through a high-speed video camera or a digital camera through a semicircular tangent high-strength resin transparent plate, and carrying out related tests in stages;
3) the method adopts different modes to carry out the injection and extraction geotechnical centrifuge test, and provides an effective test device and method for the research of the mutual dynamic response of the pile soil of the whole service life of the driven pile;
4) the geotechnical centrifuge test device and the use method can be used for developing the research on the mutual response rule of the pile soil of the driven pile in the whole life cycle, and the geotechnical centrifuge test is an effective research means with relatively low cost for analyzing the mutual response of the pile soil of the driven pile in the whole life.
Drawings
Fig. 1 is a schematic structural sectional view of a driven pile full-life-cycle geotechnical centrifuge test device provided by the invention.
Fig. 2 is a side view of fig. 1.
FIG. 3 is a top view of the vertical support system of FIG. 1.
Figure 4 a top view of the piling mast support system of figure 2.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples. In which like parts are designated by like reference numerals. It should be noted that the terms "front," "back," "left," "right," "upper" and "lower" used in the following description refer to directions in the drawings, and the terms "bottom" and "top," "inner" and "outer" refer to directions toward and away from, respectively, the geometric center of a particular component.
Referring to fig. 1-4, the invention provides a full life cycle geotechnical centrifuge test device for driven piles, which is characterized in that: the pile-driving full-life loading system comprises a supporting system, a pile-driving full-life loading system, a pile-soil system, a centrifugal machine system and a measuring and collecting system;
a support system: the device comprises a vertical supporting system and a pile driving frame supporting system, wherein the vertical supporting system mainly comprises a threaded rigid column 1, a vertical outer supporting frame 2, a vertical inner supporting frame 3 and a bottom rigid plate 24, the vertical supporting system is used for supporting the whole test model and is connected with a corresponding device of a centrifugal machine and simultaneously provides a supporting platform for the pile driving frame in the model, and the vertical outer supporting frame 2 is movably connected with the threaded rigid column 1 and is controlled to lift through a vertical support lifting motor 29;
pile driving full-life loading system: the pile driving device comprises a pile driving frame 8 (the pile driving frame is made of a specially-made rigid steel plate), pile driving equipment (such as a pile driving hammer, a vibration hammer and a static pressure device) and a horizontal loading system (such as a horizontal loading servo motor 30 and a horizontal force transmission rigid rod 31), wherein the pile driving frame supporting system is connected with a vertical supporting system, a scale is marked on the pile driving frame 8, the pile driving equipment comprises a pile driving hammer guide rail 9, a pile driving guide rail 10 and vertical loading equipment 11, a pile driving hammer pad 12 is arranged at the lower part of the vertical loading equipment 11, and the horizontal loading system simulates pile soil response of the effect of combined load during the service period of a pile; in order to ensure the stability of the piling process, 13-pile cushions are required to be paved on the model pile when hammering penetration is adopted, the 13-pile cushions are not required when static pressure and vibration penetration is adopted, and the model pile 14-pile cap and the pile hammer are required to be fixed when vibration penetration is adopted. The loading modes of the 11-vertical loading equipment are controlled by the servo and the computer, such as hammering, vibration and static pressure can be set in a penetration installation stage, static load can be set in a service operation stage, cyclic loading and torsion can be set in a service operation stage, and static load and vibration can be set in a retired pull-out stage. The loading modes can be combined at will, and the loading modes in the same stage can be combined with each other;
pile soil system: comprises a model pile 15 and a model box 18, wherein a pile cap 14 is fixed on the pile top of the model pile 15, the pile cap 14 protects the pile head of the model pile in the injection process, monitoring elements (such as a pile body strain stress and the like) of physical and mechanical variables are adhered on the pile body, the model box 18 is a semi-cylindrical box body with a closed lower part and an opened upper part, the semi-cylindrical part comprises a high-strength and high-rigidity steel plate, a drain hole 19 is distributed on the box body (the drain hole controls the drainage condition in the injection installation process, can perform initial reinforcement treatment on soil and analyze the pile soil response under different drainage conditions after the installation is completed), the semi-cylindrical section of the model box 18 comprises a high-strength resin transparent plate 28, the soil body 20 (the soil body 20 can be clay or sand soil) is distributed in the model box 18, a lifting motor 22 is fixed below a fixed support 21, the lifting motor 22 is sleeved on the threaded rigid column 1, the lifting motor 22 drives the nut to rotate to realize lifting on the threaded rigid column 1, the height 21 of the fixed support is controlled, and the model box 18 is supported by the fixed support 21 and the bottom rigid supporting block 23 and is fixed with the vertical supporting system through the high-strength rivet 25.
A centrifuge system: the test system comprises a centrifugal machine, wherein the supporting system, the driven pile life-span loading system and the pile soil system are fixedly arranged in a test cabin of the centrifugal machine, the movement of the centrifugal machine is used for applying supergravity to a test model, the fluid-solid coupling time is accelerated in a supergravity environment, the change process is accelerated, and the change process is close to the physical and mechanical state of the actual fluid-solid coupled soil body.
The measurement system comprises: the device comprises a soil body monitoring system and a pile body monitoring system, wherein the soil body monitoring system comprises a soil body monitoring element 17, the pile body monitoring system comprises a pile body monitoring element 16, the soil body monitoring element 17 is used for testing the initial stress strain, the hole pressure state and the corresponding physical mechanical parameters in the piling process and after the installation is finished, and the pile body monitoring element 16 can be used for acquiring the physical mechanical parameters such as the deformation stress of the pile body.
Referring to fig. 2, in order to acquire intuitive pile-soil contact characteristics in real time, in the above apparatus, a high-speed video camera or a high-speed digital camera is used to photograph deformation characteristics of pile-soil interaction during pile driving through a high-strength resin transparent plate 28.
Referring to fig. 1, 2, 3 and 4, the pile driver mast support system 2 (i.e. the transverse frame) is configured to support the pile driver mast 8 by the pile driver mast upper outer support 4, the pile driver mast upper inner and outer supports 5, the pile driver mast lower inner support 6, the pile driver mast lower outer support 7, the pile driver mast upper back support 26 and the pile driver mast lower back support 27, the upper outer support 4 on the left side of the pile driving frame 8, the upper inner support 5 and the lower outer support 5 of the pile driving frame, the lower inner support 6 of the pile driving frame and the lower outer support 7 of the pile driving frame are all long rods, and the upper outer support 4 on the right side, the upper inner support 5 and the lower outer support 5 of the pile driving frame, the lower inner support 6 of the pile driving frame and the lower outer support 7 of the pile driving frame are all short rods, so that the pile driving frame 8 is away from the middle position of the central model box 18, the pile driving hammer guide rail 9 and the pile driving guide rail 10 are positioned right above the pile body, and the pile driving frame can be ensured to be stable in the pile.
Referring to fig. 1, 2, 3 and 4, one end of the upper outer pile support 4 of the pile driving frame is connected to the threaded rigid column 1, and the other end is connected to the upper end of the pile driving frame 8, one end of the lower outer pile support 7 of the pile driving frame is connected to the threaded rigid column 1, and the other end is connected to the lower end of the pile driving frame 8, one end of the upper inner and outer pile support 5 of the pile driving frame is connected to the pile driving frame support system 2, and the other end is connected to the middle upper part of the pile driving frame 8, and one end of the lower inner pile support 6 of the pile driving frame is connected to the pile driving frame support system 2, and the other.
Referring to fig. 1 and 2, the mold box 18 is provided with a fixing bracket 21, the inner end of the fixing bracket 21 is pressed against the mold box 18, the other end of the fixing bracket 21 is fixed to a fixing bracket lifting motor 22, the fixing bracket lifting motor 22 is provided with a nut which is sleeved with the threaded rigid column 1 and moves up and down along the threaded rigid column 1 by a driving nut; the vertical outer support frame 2 is provided with a vertical support frame lifting motor 29; a horizontal loading servomotor 30 is fixed to the pile driving frame 8 and drives the model pile 15 laterally.
Referring to fig. 1-4, the present invention provides a method of operating the driven pile full life cycle geotechnical centrifuge test apparatus according to claim 1, comprising the steps of:
determining the size and the arrangement position of each system according to the in-situ size and the magnitude of a geotechnical centrifuge;
secondly, determining a full-life loading cycle (such as penetration-service or penetration-service-pull-out) so as to set a loading mode of the loading equipment,
thirdly, installing a supporting system, a pile-soil system and a measuring system;
installing a driven pile life-cycle loading system, wherein the loading system is a centrifuge, the driven pile life-cycle geotechnical centrifuge test device is fixedly installed in a test cabin of the centrifuge, and all systems are debugged in place;
and fifthly, carrying out a geotechnical centrifuge test.
Referring to fig. 1-4, the steps of the method are specifically:
firstly, determining the size and the arrangement of each system of the testing device: the test is to analyze the full-life cycle pile-soil response of a large-diameter open pile foundation in-situ saturated clay, the in-situ size of the pile is 8m in pile diameter, 80m in pile length, 9cm in wall thickness, the saturated clay is ocean saturated clay, the fluid is seawater, the installation mode adopts hammering penetration, and the extraction mode adopts static pressure; the size of the model pile 15 is set to be 5.34cm in diameter, 53.34cm in pile length and 0.6mm in wall thickness; the pile body is uniformly and symmetrically provided with 10 grating optical fiber points on each side, the grating optical fiber soil pressure miniature boxes and osmometers in the soil body are respectively and symmetrically arranged in 3 rows, the two test elements are arranged at intervals in 12 rows, and each row is 8 along the height direction; the size of the model box is 1.5m in diameter and 1.0m in height, 10 grating fiber points are uniformly distributed on the drain holes along the height direction of the model box, 10 grating fiber points are uniformly distributed on the bottom along the diameter direction, and 15 rows of grating fiber soil pressure miniature boxes and osmometers are distributed along the arc direction; the length of the pile driving frame 8 is 1.2m, the width of the pile driving frame is 0.25m, the pile driving hammer guide rail 9 and the pile driving guide rail 10 are uniformly and symmetrically distributed on the pile driving frame 8, the pile driving frame 8 is symmetrically fixed in a vertical supporting system along the length direction (the vertical supporting system and the pile driving frame supporting system are formed by anchoring high-strength I-shaped steel of 8# B-12# B through rivets, the pile driving frame supporting system and the pile driving frame are also anchored through rivets, and the height of the threaded rigid column 1 is 1.8 m and the diameter of the threaded rigid column 1 is 1.2 cm.);
determining a full-life loading cycle and setting a loading mode: adopting a penetration mode as hammering, wherein the pile bears the action of vertical static load and horizontal cyclic load on the upper part during service, the extraction mode is static load, different loading modes are selected according to different loads at different loading stages, corresponding vertical loading is selected, the horizontal loading mode and the vertical extraction mode are both servo-controlled, and the vertical loading device adopts hammering at the penetration installation stage; the pile pad is in static load in a service operation stage, and is fixed with the pile pad through automatic buckles or electromagnetic electrification magnetic force in a retired pulling-out stage so as to pull out the pile pad in the static load;
thirdly, installing a supporting system, a pile-soil system and a measuring system;
installing a driven pile life-cycle loading system, wherein the loading system is a centrifuge, the driven pile life-cycle geotechnical centrifuge test device is fixedly installed in a test cabin of the centrifuge, and all systems are debugged in place;
fifthly, carrying out a geotechnical centrifuge test: the geotechnical centrifuge has the loading gravity of 150g, a hammering penetration test is carried out after loading, monitoring data are collected through a wireless collection system, a hammering penetration process is recorded through a high-definition high-speed computer, and hammering penetration of a pile hammer is controlled through wireless servo control; secondly, after the penetration is completed, a long-term bearing performance test is carried out, a pile-soil interaction test that the pile is subjected to combined load (under the action of vertical static load and horizontal cyclic load) is researched, after the duration of the test requirement, data are always kept in a collection state in the period, servo control is converted into a pulling-out mode, a pulling-out test is carried out, relevant data are collected through a wireless collection system, and the pulling-out process is recorded by a high-speed camera. And further complete the geotechnical centrifuge test research of the bearing characteristic of the whole service life.
Referring to fig. 1 and 2, in the method: vertical loading equipment 11 confirms the loading mode according to what kind of stage the stake is in among the test process, penetrate the installation period and select the hammering hammer, vibratory hammer and static pressure hammer, the hammering hammer adopts hydraulic hammer (like diesel oil hydraulic hammer), the hydraulic hammer adopts the drive of electromagnetic impact mode, the service operation period adopts the static load mode, the mode of pulling out of retirement during the period of pulling out can adopt vibration to pull out and the static load is pulled out, it adopts solenoid electric control to pull out equipment, the magnetic force of accessible electric current change control hammer blanket, guarantee the pile cap, pile blanket and hammer blanket and model stake are fixed as an organic whole at the in-process of pulling out, can adopt automatic card to fix equipment and fix.
The above description is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments, and all technical solutions belonging to the idea of the present invention belong to the protection scope of the present invention. It should be noted that modifications and embellishments within the scope of the invention may occur to those skilled in the art without departing from the principle of the invention, and are considered to be within the scope of the invention.
Claims (8)
1. The utility model provides a driven pile full life cycle geotechnique centrifuge test device which characterized by: the pile-driving full-life loading system comprises a supporting system, a pile-driving full-life loading system, a pile-soil system, a centrifugal machine system and a measuring and collecting system;
a support system: the vertical support system mainly comprises a threaded rigid column, a vertical outer support frame, a vertical inner support frame and a bottom rigid plate, the vertical support system is used for supporting the whole test model and is connected with a corresponding device of a centrifugal machine, and meanwhile, a support platform is provided for the pile driving frame in the model, and the vertical outer support frame is movably connected with the threaded rigid column and is controlled to lift through a vertical support lifting motor;
pile driving full-life loading system: the pile driving device comprises a pile driving frame, pile driving equipment and a horizontal loading system, wherein the pile driving frame supporting system is connected with a vertical supporting system, a scale is marked on the pile driving frame, the pile driving equipment comprises a pile driving hammer guide rail, a pile driving guide rail and vertical loading equipment, a pile driving hammer pad is arranged at the lower part of the vertical loading equipment, and the horizontal loading system simulates pile soil response of the action of combined load during the service period of a pile; adjusting the loading mode of the vertical loading equipment through a servo and a computer;
pile soil system: the device comprises a model pile and a model box, wherein a pile cap is fixed on the pile top of the model pile, the pile cap protects the pile head of the model pile in the injection process, a monitoring element of physical and mechanical variables is adhered to the pile body, the model box is a semi-cylindrical box body with a closed lower part and an open upper part, the semi-circular part consists of a high-strength and high-rigidity steel plate, a drain hole is distributed on the box body, the semi-circular section of the model box consists of a high-strength resin transparent plate, a soil body is distributed in the model box, a lifting motor is fixed below a fixed support and is sleeved on a threaded rigid column, and the lifting motor drives a nut to rotate to realize lifting on the threaded rigid column and control the height of the fixed support;
a centrifuge system: the test device comprises a centrifuge, wherein a support system, a driven pile life-span loading system and a pile soil system are fixedly arranged in a test cabin of the centrifuge, the movement of the centrifuge is used for applying supergravity to a test model, the fluid-solid coupling time is accelerated in a supergravity environment, and the change process is accelerated;
the measurement system comprises: the pile body monitoring system comprises a pile body monitoring element, the pile body monitoring element tests the initial stress strain, the hole pressure state and the corresponding physical mechanical parameters in the piling process and after the pile is installed, and the pile body monitoring element collects the physical mechanical parameters such as the deformation stress of the pile body.
2. The driven pile full life cycle geotechnical centrifuge test apparatus according to claim 1, wherein: and a high-speed video camera or a high-speed digital camera is adopted to shoot deformation characteristics of pile-soil interaction in the piling process through the high-strength resin transparent plate.
3. A driven pile full life cycle geotechnical centrifuge test apparatus as claimed in claim 1 or 2, wherein: the pile driving frame supporting system is provided with an upper outer support of a pile driving frame, an upper inner support and a lower inner support of the pile driving frame, a lower outer support of the pile driving frame, an upper back support of the pile driving frame and a lower back support of the pile driving frame for supporting the pile driving frame, the upper outer support on the left side of the pile driving frame, the upper inner support and the lower outer support of the pile driving frame, the upper outer support and the lower inner support of the pile driving frame, the lower inner support of the pile driving frame and the lower outer support of the pile driving frame are all long rods, the upper outer support and the lower outer support of the pile driving frame, the lower inner.
4. A driven pile full life cycle geotechnical centrifuge test apparatus as claimed in claim 3, wherein: the upper outer support end of the pile driving frame is connected with the threaded rigid column, the other end of the upper outer support of the pile driving frame is connected with the upper end of the pile driving frame, the lower outer support end of the pile driving frame is connected with the threaded rigid column, the other end of the lower outer support of the pile driving frame is connected with the lower end of the pile driving frame, one end of the upper inner support and the lower inner support of the pile driving frame is connected with the pile driving frame supporting system, the other end of the upper inner support and the lower inner support of the pile driving frame is connected with the middle upper portion of the pile.
5. A driven pile full life cycle geotechnical centrifuge test apparatus as claimed in claim 1 or 2, wherein: the model box is provided with a fixed support, the inner side end of the fixed support is tightly pressed on the model box, the other end of the fixed support is fixed on a fixed support lifting motor, the fixed support lifting motor is provided with a nut which is sleeved with the threaded rigid column and moves up and down along the threaded rigid column through a driving nut; the vertical outer support frame is provided with a vertical support lifting motor, and a horizontal loading servo motor is fixed on the pile driving frame and transversely drives the model pile through a horizontal force transmission rigid rod.
6. A method of operating the driven pile full life cycle geotechnical centrifuge test apparatus of claim 1, wherein: the method comprises the following steps:
determining the size and the arrangement position of each system according to the in-situ size and the magnitude of a geotechnical centrifuge;
secondly, determining the life-cycle loading cycle, thereby setting the loading mode of the loading equipment,
thirdly, installing a supporting system, a pile-soil system and a measuring system;
installing a driven pile life-cycle loading system, wherein the loading system is a centrifuge, the driven pile life-cycle geotechnical centrifuge test device is fixedly installed in a test cabin of the centrifuge, and all systems are debugged in place;
and fifthly, carrying out a geotechnical centrifuge test.
7. The method of operating a driven pile full life cycle geotechnical centrifuge test apparatus as claimed in claim 6, wherein: the steps are specifically as follows:
firstly, determining the size and the arrangement of each system of the testing device: the test is to analyze the full-life cycle pile-soil response of a large-diameter open pile foundation in-situ saturated clay, the in-situ size of the pile is 8m in pile diameter, 80m in pile length, 9cm in wall thickness, the saturated clay is ocean saturated clay, the fluid is seawater, the installation mode adopts hammering penetration, and the extraction mode adopts static pressure; the size of the model pile is set to be 5.34cm in diameter, 53.34cm in pile length and 0.6mm in wall thickness; the pile body is uniformly and symmetrically provided with 10 grating optical fiber points on each side, the grating optical fiber soil pressure miniature boxes and osmometers in the soil body are respectively and symmetrically arranged in 3 rows, the two test elements are arranged at intervals in 12 rows, and each row is 8 along the height direction; the size of the model box is 1.5m in diameter and 1.0m in height, 10 grating fiber points are uniformly distributed on the drain holes along the height direction of the model box, 10 grating fiber points are uniformly distributed on the bottom along the diameter direction, and 15 rows of grating fiber soil pressure miniature boxes and osmometers are distributed along the arc direction; the length of the pile driving frame is 1.2m, the width of the pile driving frame is 0.25m, the pile driving hammer guide rail and the pile driving guide rail are uniformly and symmetrically vertically distributed on the pile driving frame, and the pile driving frame is symmetrically fixed in the vertical supporting system along the length direction;
determining a full-life loading cycle and setting a loading mode: adopting a penetration mode as hammering, wherein the pile bears the action of vertical static load and horizontal cyclic load on the upper part during service, the extraction mode is static load, different loading modes are selected according to different loads at different loading stages, corresponding vertical loading is selected, the horizontal loading mode and the vertical extraction mode are both servo-controlled, and the vertical loading device adopts hammering at the penetration installation stage; the pile pad is in static load in a service operation stage, and is fixed with the pile pad through automatic buckles or electromagnetic electrification magnetic force in a retired pulling-out stage so as to pull out the pile pad in the static load;
thirdly, installing a supporting system, a pile-soil system and a measuring system;
installing a driven pile life-cycle loading system, wherein the loading system is a centrifuge, the driven pile life-cycle geotechnical centrifuge test device is fixedly installed in a test cabin of the centrifuge, and all systems are debugged in place;
fifthly, carrying out a geotechnical centrifuge test: the geotechnical centrifuge has the loading gravity of 150g, a hammering penetration test is carried out after loading, monitoring data are collected through a wireless collection system, a hammering penetration process is recorded through a high-definition high-speed computer, and hammering penetration of a pile hammer is controlled through wireless servo control; secondly, after the penetration is completed, a long-term bearing performance test is carried out, a pile-soil interaction test of the pile under combined load is researched, after the duration of the test requirement, data are always kept in a collection state in the duration, servo control is converted into a pulling-out mode, a pulling-out test is carried out, relevant data are collected through a wireless collection system, the pulling-out process is recorded through a high-speed camera, and further the geotechnical centrifuge test research of the bearing characteristic of the whole service life is completed.
8. A method of operating a driven pile full life cycle geotechnical centrifuge test apparatus as claimed in claim 6 or claim 7, wherein: the vertical loading equipment determines a loading mode according to which stage the pile is in the test process, the hammer, the vibration hammer and the static pressure hammer are selected in the injection installation period, the hammer adopts a hydraulic hammer, the hydraulic hammer is driven in an electromagnetic impact mode, the static load mode is adopted in the service period, the pulling-out mode in the decommissioning pulling-out period can adopt vibration pulling-out and static load pulling-out, the pulling-out equipment adopts electromagnetic control, the magnetic force of the hammer pad can be changed and controlled through current, it is ensured that the pile cap, the pile pad, the hammer pad and the model pile are fixed into a whole in the pulling-out process, and automatic clamping equipment is adopted for fixing.
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| CN202010902475.5A CN112160349A (en) | 2020-09-01 | 2020-09-01 | Full-life-cycle geotechnical centrifuge test device for driven pile and operation method thereof |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112962685A (en) * | 2021-02-01 | 2021-06-15 | 浙江大学 | Pile pressing verticality control injection device for pile foundation centrifugal test |
| US20220064896A1 (en) * | 2020-09-01 | 2022-03-03 | Wenzhou University | Device for centrifuge testing of driven pile in different installation and pull-out modes and operation method therefor |
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2020
- 2020-09-01 CN CN202010902475.5A patent/CN112160349A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20220064896A1 (en) * | 2020-09-01 | 2022-03-03 | Wenzhou University | Device for centrifuge testing of driven pile in different installation and pull-out modes and operation method therefor |
| US11739494B2 (en) * | 2020-09-01 | 2023-08-29 | Wenzhou University | Device for centrifuge testing of driven pile in different installation and pull-out modes and operation method therefor |
| CN112962685A (en) * | 2021-02-01 | 2021-06-15 | 浙江大学 | Pile pressing verticality control injection device for pile foundation centrifugal test |
| CN112962685B (en) * | 2021-02-01 | 2022-04-26 | 浙江大学 | Pile pressing verticality control injection device for pile foundation centrifugal test |
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