CN210917492U - Multidirectional-loading expansive soil pile foundation experimental device - Google Patents
Multidirectional-loading expansive soil pile foundation experimental device Download PDFInfo
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Abstract
The utility model discloses a can multidirectional loaded inflation soil pile foundation experimental apparatus belongs to inflation soil pile foundation experiment technical field, including water tank, water inlet connection pipe, box, gravel layer, coarse sand layer, fine sand layer, bloated soil foundation, immersion tube, model stake and foil gage. The utility model discloses test device has the loaded function of soaking water loss and multidirectional load concurrently, through model test, the research soaks in-process single pile lift with pile body internal force change law, the bearing characteristic of single pile around the contrast analysis inflation soil soaks, for the design of pile foundation in the inflation soil and subsequent theoretical analysis provide experimental foundation, arrange in order the test data of record, calculate and revise pile body strain value and obtain pile side axle power and pile side frictional resistance etc. combine pile bolck load and settlement volume to obtain model pile Q-s curve.
Description
Technical Field
The utility model relates to an inflation soil pile foundation experiment technical field especially relates to a can multidirectional loaded inflation soil pile foundation experimental apparatus.
Background
The swelling soil can take place the bulging deformation along with the increase of water content on the one hand, and its intensity of on the other hand can obviously reduce, under the two combined action, can produce certain influence to the building safety of the building (structure) that is located on the swelling soil foundation. Practice proves that the pile foundation can effectively resist damage to the superstructure caused by swelling and shrinkage of expansive soil. For the pile foundation in the expansive soil foundation, the expansive soil can generate uplifting force on the pile foundation when being soaked in water and raised, and the pile foundation is provided with downward pulling force when losing water and contracting. In addition, the pile foundation can generate horizontal expansion force in the expansion process. It can be seen that the pile-soil interaction in expansive soil foundations is more complex than that of general soil, and the load transfer mechanism is different. Therefore, the research on the interaction mechanism of the expansive soil and the pile has important engineering significance.
For can be better for providing experimental data in the actual engineering, solve present actual inflation soil foundation ground foundation pile setting in earlier stage, can reduce the atress influence of inflation soil breathing to the foundation pile, need set up an experimental apparatus.
SUMMERY OF THE UTILITY MODEL
An object of the utility model is to provide a can multidirectional loaded inflation soil pile foundation experimental apparatus solves the atress that inflation soil foundation bloated contract influences the foundation pile that expands, lowers the technical problem in the life-span of building.
An expansive soil pile foundation experimental device capable of being loaded in multiple directions comprises a water tank, a water inlet connecting pipe, a box body, a gravel layer, a coarse sand layer, a fine sand layer, an expansive soil foundation, a water soaking pipe, a model pile and a strain gauge;
the water tank is through the bottom intercommunication of connecting pipe and box of intaking, the gravel layer is placed in the bottom half, the gravel layer sets up the upper end on the gravel layer, fine sand layer sets up the upper end on coarse sand layer, bloated soil foundation sets up on fine sand layer, inside the immersion pipe inserted the box, bottom and gravel layer intercommunication, the bloated soil foundation surface of top protrusion, the model pile inserts in bloated soil foundation, and the top exposes bloated soil foundation surface, the foil gage sets up on the side of model pile, and draws forth outside strain tester through the wire and connect.
Furthermore, the side edge of the box body is provided with a bevel edge supporting frame, the bevel edge supporting frame is provided with a sliding groove, and the side edge of the sliding groove is provided with a fixing hole.
Furthermore, a reaction frame is arranged on the sliding groove, a transverse shifting plate is arranged at the top end of the reaction frame, a jack is arranged on the transverse shifting plate, one side of the reaction frame is arranged in the sliding groove at the front end of the box body, and the other side of the reaction frame is arranged in the sliding groove at the rear end.
Further, the utility model discloses still include ball pivot, force sensor and pile cap, the pile cap is detained at model pile top portion, force sensor sets up on the pile cap, the ball pivot sets up the top at force sensor, the ball pivot top is provided with spherical groove, force sensor is connected with outside strain tester, the flexible bottom and the ball pivot contact of jack are connected.
Furthermore, a loading frame is arranged on the sliding groove, one side of the loading frame is arranged in the sliding groove on the left side of the box body, the other side of the loading frame is arranged in the sliding groove on the right side of the box body, a pulley is arranged on the loading frame, a transverse force sensor and an iron frame are arranged on the loading frame, the iron frame passes through the pulley through a steel wire rope and is connected with the top of the model pile through the transverse force sensor, a weighting block is arranged on the iron frame, and the steel wire ropes on the two sides of the pulley form a right-angle.
Further, the utility model discloses still include loading mound, stake raft and soil moisture sensor, the stake raft sets up at bloated soil foundation surface, stake raft bottom is provided with the model stake of a plurality of equidistant settings, and the fixed setting of stake raft is on the model stake of a plurality of equidistant settings, the loading mound sets up on the stake raft, soil moisture sensor sets up in the soil foundation that expands of the model stake side of a plurality of equidistant settings, and soil moisture sensor passes through the wire and is connected with outside computer or host computer display screen.
Further, the utility model discloses still include vertical displacement meter and vertical load case, the vertical setting of vertical displacement meter is on the loading mound, vertical load case sets up on the loading mound, the flexible bottom and the top of vertical load case of jack are connected.
Further, the utility model discloses still include lateral displacement meter and horizontal load case, the iron stand frame passes the pulley through horizontal load case and is connected with loading mound top through wire rope, the lateral displacement meter transversely sets up on the side of loading mound.
Furthermore, the utility model also comprises a three-degree-of-freedom loader, which comprises a vertical support plate of degree of freedom, a vertical displacement meter of degree of freedom, a horizontal support plate of degree of freedom, a deviation displacement meter of degree of freedom, a stress rod of degree of freedom, a horizontal fixed plate of degree of freedom, a pressure arc frame of degree of freedom, a load box of degree of freedom and a vertical fixed plate of degree of freedom, wherein the top end of the vertical support plate of degree of freedom is fixed on a jack on a reaction frame, the vertical fixed plate of degree of freedom is fixed on the vertical support plate of degree of freedom, the vertical displacement meter of degree of freedom is vertically arranged on the vertical fixed plate of degree of freedom, the horizontal support plate of degree of freedom is transversely fixed on the vertical fixed plate of degree of freedom, the horizontal displacement meter of freedom is transversely fixed on the horizontal fixed plate of, the freedom degree pressure arc frame is arranged in the freedom degree transverse fixing plate, the freedom degree load box is arranged on the loading pier, one end of the freedom degree stress rod is arranged at the top of the freedom degree load box, and the top end of the freedom degree stress rod is in vertical contact with the freedom degree pressure arc frame and is connected with the freedom degree pressure arc frame.
Furthermore, a connecting piece is arranged between the pile raft and the model pile, the connecting piece comprises an inner sleeve bonding section, a connecting section and a thread section, the inner sleeve bonding section, the connecting section and the thread section are fixedly connected at one time, the inner sleeve bonding section is sleeved in the model pile and is bonded, a wire outlet hole is formed in the upper end of the side edge of the connecting section, a penetrating hole and a wire outlet groove are formed in the pile raft, the connecting section penetrates through the penetrating hole of the pile raft, a wire is led out from the wire outlet hole and the wire outlet groove, a screw thread is arranged in the thread section and connected, and the pile raft is screwed tightly.
The utility model adopts the above technical scheme, the utility model discloses following technological effect has:
the utility model discloses test device has the loaded function of soaking water loss and multidirectional load concurrently, through model test, the research soaks in-process single pile lift with pile body internal force change law, the bearing characteristic of single pile around the contrast analysis inflation soil soaks, for the design of pile foundation in the inflation soil and subsequent theoretical analysis provide experimental foundation, arrange in order the test data of record, calculate and revise pile body strain value and obtain pile side axle power and pile side frictional resistance etc. combine pile bolck load and settlement volume to obtain model pile Q-s curve.
Drawings
Fig. 1 is the utility model discloses a vertical experimental structure section view of single pile.
Fig. 2 is a cross-sectional view of the single-pile transverse experimental structure of the present invention.
Fig. 3 is a sectional view of the vertical experimental structure of the grouped piles of the present invention.
Fig. 4 is a cross-sectional view of the horizontal experimental structure of the pile group of the present invention.
Fig. 5 is a sectional view of the pile group freedom degree loading experiment structure of the present invention.
Fig. 6 is a schematic view of the structure of the connector of the present invention.
Fig. 7 is a top view of the surface of the case of the present invention.
Fig. 8 shows the results of the elastic modulus test of the present invention.
Numbering in the figures: 1-water tank, 1.1-water inlet connecting pipe, 2-box body, 2.1-bevel edge supporting frame, 2.2-chute, 3-gravel layer, 4-coarse sand layer, 5-fine sand layer, 6-soil swelling foundation, 7-water soaking pipe, 8-model pile, 9-strain gauge, 10-reaction frame, 11-jack, 12-ball hinge, 13-force sensor, 14-pile cap, 15-loading frame, 16-transverse force sensor, 17-pulley, 18-iron frame, 19-vertical displacement meter, 20-vertical loading box, 21-loading pier, 22-pile raft, 23-soil moisture sensor, 24-transverse displacement meter, 25-transverse loading box, 26-three-degree-of-freedom loading instrument, 26.1-degree-of-freedom vertical supporting plate, 26.2-freedom degree vertical displacement meter, 26.3-freedom degree horizontal displacement meter, 26.4-freedom degree horizontal support plate, 26.5-freedom degree deflection displacement meter, 26.6-freedom degree stress rod, 26.7-freedom degree horizontal fixing plate, 26.8-freedom degree pressure arc frame, 26.9-freedom degree load box, 26.10-freedom degree vertical fixing plate, 27-connecting piece, 27.1-inner sleeve bonding section, 27.2-connecting section, 27.3-wire outlet hole, 27.4-thread section and 27.5-screw.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail below with reference to the accompanying drawings and by referring to preferred embodiments. It should be understood, however, that the numerous specific details set forth in the specification are merely set forth to provide a thorough understanding of one or more aspects of the present invention, which may be practiced without these specific details.
Example 1:
as shown in fig. 1, according to the utility model discloses a but multidirectional loaded inflation soil pile foundation experimental apparatus, including water tank 1, the connecting pipe of intaking 1.1, box 2, gravel layer 3, coarse sand layer 4, fine sand layer 5, bloated soil foundation 6, immersion tube 7, model stake 8 and foil gage 9.
The size of a model box (box body 2) is 1000mm × 1000mm × 1000mm, the model box is formed by welding iron plates with the thickness of 4mm, as shown in figure 1, in order to prevent the model box from being extruded and damaged after expansive soil is soaked in water and expanded, three sections of section steel are respectively arranged at the top, the middle and the bottom outside the model box and are welded and fixed, two channels are respectively welded at two sides of the top of the model box, and angle steel is welded at the other two sides of the top of the model box, so that the stability of the model box is enhanced, the placing and horizontal moving of an upper loading system are realized on the other hand, two water inlet holes with the diameter of 20mm are respectively arranged at two sides of the bottom of the model box.
Example 2:
as shown in fig. 1, a bevel edge support frame 2.1 is arranged on the side edge of the box body 2, a sliding groove 2.2 is arranged on the bevel edge support frame 2.1, and a fixing hole is arranged on the side edge of the sliding groove 2.2. The chute 2.2 facilitates measurement of the model piles 8 at a plurality of different positions during the measurement process.
Example 3:
as shown in FIG. 1, a reaction frame 10 is arranged on the chute 2.2, a transverse shifting plate is arranged at the top end of the reaction frame 10, a jack 11 is arranged on the transverse shifting plate, one side of the reaction frame 10 is arranged in the chute ([ 2 ] at the front end of the box body 2, and the other side is arranged in the chute 2.2 at the rear end, and the movement of the jack 11 to different positions is realized by the transverse shifting plate and the reaction frame 10, so that the model piles 8 at different positions can be measured.
Example 4:
as shown in fig. 1, the utility model discloses still include ball pivot 12, force sensor 13 and pile cap 14 in the implementation, pile cap 14 is detained at model stake 8 top, force sensor 13 sets up on pile cap 14, ball pivot 12 sets up the top at force sensor 13, ball pivot 12 top is provided with spherical groove, force sensor 13 is connected with outside strain tester, jack 11's flexible bottom and ball pivot 12 contact are connected.
Example 5:
as shown in fig. 2, a loading frame 15 is arranged on the chute 2.2, one side of the loading frame is arranged in the chute 2.2 on the left side of the box body 2, the other side of the loading frame is arranged in the chute 2.2 on the right side, a pulley 17 is arranged on the loading frame 15, a transverse force sensor 16 and an iron frame 18 are arranged on the loading frame 15, the iron frame 18 passes through the pulley 17 through a steel wire rope and is connected with the top of the model pile 8 through the transverse force sensor 16, a weighting block is arranged on the iron frame 18, and the steel wire ropes on two sides of the pulley 17 form a right-angle structure.
Example 6:
as shown in fig. 3, the utility model discloses still include loading mound 21, stake raft 22 and soil moisture sensor 23 in the implementation, stake raft 22 sets up on bloated soil foundation 6 surfaces, stake raft 22 bottom is provided with the model stake 8 of a plurality of equidistant settings, and stake raft 22 is fixed to be set up on the model stake 8 of a plurality of equidistant settings, loading mound 21 sets up on stake raft 22, soil moisture sensor 23 sets up in the bloated soil foundation 6 of the model stake 8 side of a plurality of equidistant settings, and soil moisture sensor 23 passes through the wire and is connected with outside computer or host computer display screen.
Example 7:
as shown in fig. 3, the utility model discloses still include vertical displacement meter 19 and vertical load box 20 in the implementation, vertical setting of vertical displacement meter 19 is on loading mound 21, vertical load box 20 sets up on loading mound 21, the flexible bottom and the top of vertical load box 20 of jack 11 are connected.
Example 8:
as shown in fig. 4, the utility model discloses still include lateral displacement meter 24 and horizontal load box 25 in the implementation, iron stand frame 18 passes pulley 17 through wire rope and is connected with loading mound 21 top through horizontal load box 25, lateral displacement meter 24 transversely sets up on the side of loading mound 21.
Example 9:
as shown in fig. 6, the present invention further includes a three-degree-of-freedom loader 26, where the three-degree-of-freedom loader 26 includes a vertical support plate 26.1 for degree of freedom, a vertical displacement meter 26.2 for degree of freedom, a lateral displacement meter 26.3 for degree of freedom, a lateral support plate 26.4 for degree of freedom, a deviation displacement meter 26.5 for degree of freedom, a stress rod 26.6 for degree of freedom, a lateral fixing plate 26.7 for degree of freedom, a pressure arc frame 26.8 for degree of freedom, a load box 26.9 for degree of freedom, and a vertical fixing plate 26.10 for degree of freedom, the top end of the vertical support plate 26.1 for degree of freedom is fixed on the jack 11 of the reaction frame 10, the vertical fixing plate 26.10 for degree of freedom is fixed on the vertical support plate 26.1 for degree of freedom, the vertical displacement meter 26.2 for degree of freedom is vertically disposed on the vertical fixing plate 26.10 for degree of freedom, the lateral support plate 26.4 for degree of freedom is horizontally fixed on the vertical fixing plate 26.10 for, the degree of freedom lateral displacement meter 26.3 is transversely fixed on the degree of freedom transverse fixing plate 26.7, the degree of freedom pressure arc-shaped frame 26.8 is arranged in the degree of freedom transverse fixing plate 26.7, the degree of freedom load box 26.9 is arranged on the loading pier 21, one end of the degree of freedom stress rod 26.6 is arranged at the top of the degree of freedom load box 26.9, and the top end of the degree of freedom stress rod is vertically contacted and connected with the degree of freedom pressure arc-shaped frame 26.8. The three-degree-of-freedom loader 26 applies loads from different directions, and tests of loads at different angles can be achieved. Has better effect.
Example 10:
a connecting piece 27 is arranged between the pile raft 22 and the model pile 8, the connecting piece 27 comprises an inner sleeve bonding section 27.1, a connecting section 27.2 and a thread section 27.4, the inner sleeve bonding section 27.1, the connecting section 27.2 and the thread section 27.4 are fixedly connected at one time, the inner sleeve bonding section 27.1 is sleeved in the model pile 8 and is bonded, a wire outlet hole 27.3 is formed in the upper end of the side edge of the connecting section 27.2, a through hole and a wire outlet groove are formed in the pile raft 22, the connecting section 27.2 penetrates through the through hole of the pile raft 22, a lead is led out from the wire outlet hole 27.3 and the wire outlet groove, a screw 27.5 is arranged on the thread section 27.4 for threaded connection, and the pile raft 22 is screwed. The connecting piece 27 can better fix the pile raft 22 and the model pile 8, and meanwhile, the wires are led out, so that the problem of difficulty in wiring is solved.
The loading system is divided into vertical and horizontal loading devices (as shown in fig. 1-2), which are placed on the top of the model box during loading and mechanically fixed with the model box through a G-shaped clamp to prevent the devices from shifting during loading. The vertical loading device mainly comprises a reaction frame and a jack, the jack is used for carrying out vertical grading loading on the model pile, the model pile is formed by welding rectangular steel, I-shaped steel and channel steel, and the height of the model pile is 950 mm. The vertical rectangular steel in both sides sets up two bolt holes that are 10mm in diameter side by side every 100mm from the top to the bottom, realizes the regulation to loading height. The loading beam is I-shaped steel, an iron plate with a bolt groove is welded at the bottom of the loading beam, and the bolt groove is connected with a jack with an inverted bottom through a bolt, so that the transverse adjustment of a loading position can be realized. The horizontal loading device utilizes a heavy object to carry out horizontal grading loading on the model pile and is mainly formed by welding angle steel and an iron bar. The iron rod suspends a pulley, and the horizontal loading direction is ensured by adjusting the suspension height. The steel strand wires pass through one end of the pulley to be connected with the pile head, and the other end of the pulley is matched with the iron hanging basket for loading.
As shown in the figure 1-2, a 250mm thick sand layer is buried in the bottom of the mold box, and gravel, coarse sand and fine sand are respectively filled from the bottom to the top. Set up a plurality of vertical soaking passageways in the inflation soil foundation, be 16 mm's PVC hose by a plurality of diameters and constitute, list the water hole at hose cross arrangement 4 to at the bottom of geotechnological cloth parcel tube and lateral wall, prevent that the inflation soil from blockking up the apopore, insert the molding box bottom gravel layer 150mm with the immersion pipe bottom during the experiment. The bucket is connected with the bottom of the model box by a water pipe, water is added into the bucket by using a siphon principle, and the water level is continuously controlled to be consistent with the high layer of the soil surface to realize the full-soaking expansion effect of the expansive soil, so that the purpose of simulating the expansion characteristic of the expansive soil is achieved.
The test soil sample is taken from the vicinity of Guangxi Nanning city water buffalo research institute, is gray expansive soil, has a free expansion rate of 65.5 percent, belongs to medium expansive soil according to national standard 'expansive soil regional building technical specification' (GB50112-2013), and has the basic physical property indexes shown in Table 1. The soil is dried and crushed to prepare a soil sample with the initial water content of 20 percent. The soil sample is manually compacted to be filled in layers, the thickness of each layer after compaction is controlled to be 100mm, the total height of the filled soil is 700mm, and the dry density of the filled soil layer is 1.45g/cm 3.
TABLE 1 basic physical Properties of the expansive soil
The model test adopts an aluminum alloy hollow pipe to manufacture a model pile, the total length of the model pile is determined to be 700mm from the previous section, the outer diameter is 25mm, the wall thickness is 2mm, the depth of the model pile into the soil is 600mm, the length above the soil surface is 100mm, a round hole with the diameter of 5mm is reserved at a position 30mm below the pile top, in order to lead out an inner strain gauge lead, in order to measure the strain value of the pile body, strain gauges are pasted along the inner side of the pile body, the strain gauges of vertical loaded single piles are arranged at equal intervals, the strain gauges of horizontal loaded single piles are arranged to be dense at the top, the strain gauges adopt Zhejiang yellow rock resistance strain gauges with the base size of 0.5mm × 0.5.5 mm and the resistance value of 119.9 +/-0.1 omega to paste the strain gauges, the model pile is cut into halves before pasting the strain gauges, the position of the strain gauges are marked on the pile body, the strain gauges are polished smoothly by using 502 glue, the strain gauges are pasted to the strain gauges, the strain gauges are pasted to the mark position of the pile body, the strain gauge is cut into a wire, the epoxy resin is pasted to be stuck on the bottom of the pile, and the epoxy resin, the nylon plug is pasted to be completely dissolved, and the nylon.
After the model pile is bonded, simply supporting two ends of the model pile by using a TST3822EN static strain tester, calibrating the model pile by using a simply supported beam bending moment method, and measuring the elastic modulus of the model pile (as shown in FIG. 6). And in the loading measurement process, the direction of the bonding surface of the strain gauge of the model pile is ensured to be vertical downwards, and the strain gauge is connected through the pile body in a guiding manner. And after loading is finished, the surface direction of the strain gauge is vertically upward, and the operations are repeated to load and record data.
The bending moment at each strain gage is first calculated from material mechanics:
M＝F(L-h)/2 (1)
wherein: m is the foil gage department and calculates the moment of flexure, and F is the vertical load that simple beam central point put the department and applys, and L is simple beam total length, because the foil gage position of model stake is not hugged closely pile bolck and pile bottom, and simple length L equals 0.58M among the calibration process, and h is the distance of foil gage distance simple fulcrum.
And calculating the coefficient of the relation between the strain value and the bending moment according to a formula by using the strain obtained by the strain acquisition instrument:
for the test model pile, the distance y between the strain gauge and the neutral axis is 0.0105 m. E is the elastic modulus of the strain gauge at the section; i is a section moment of inertia; ε represents the strain of the strain gauge.
And drawing a relation curve of bending moment, section geometric parameters and strain to obtain a slope, obtaining a relation coefficient of the bending moment and the strain of the pile body at the section, and drawing a curve as shown in fig. 8, wherein the elastic modulus of the model pile is 69.5 GPa. After the calibration is finished, a layer of fine sand is adhered to the outer side of the pile body by using epoxy resin, so that the roughness of the pile body is increased, and the pile soil has certain friction force.
For a single-pile test in a model box, the boundary effect of the box wall on the constraint of the soil mass around the pile and the soil squeezing effect of adjacent piles when the pile center distance s is too small need to be considered. The hole compendium and the like (2009) research shows that when the distance between the model pile and the model box wall is more than 3 times of the pile diameter d, the boundary effect can be ignored. The Dynasty et al (2011) think that for an ultra-long pile, when the center distance s of the pile reaches more than 10 times of the diameter d of the pile, the influence of pile group effect can be ignored. The building pile technical Specification (JGJ94-2008) considers pile thinning (piles with s >6 d) to be equivalent to single piles. The shortest distance between the model pile and the box wall is 250mm, the pile spacing is 500mm, and the influence of the size effect in the test is calculated as follows:
distance between the model pile and the wall of the model box: 250/25 is 10>3, which satisfies the distance requirement between the model pile and the model box wall;
pile spacing: 500/25 ═ 20>10, satisfying the pile spacing requirement neglecting the effects of pile group effects.
Therefore, the boundary effect in the experiment can be ignored, and the model pile is considered as a single pile.
The model piles are arranged in the plane of the model box in the test. Particularly, the soaking pipe is made of a PVC hose, so that the soaking pipe is inevitably bent and deformed in the process of ramming soil in layers, so that the top of the soaking pipe deviates from a preset position, but the realization of the soaking function of the expansive soil is not influenced.
Tabl can know from the results of the previous geotechnical experiments that the strength of the expansive soil is obviously reduced after the expansive soil meets water, and the expansive soil shows obvious expansibility, so that the working properties of pile foundations are influenced. If the expansive soil swells in water, uplift force is generated on the pile, and the shrinkage caused by dehydration generates pull-down force on the pile, so that the pile-soil combined action in the expansive soil is more complicated than that in the common soil. Therefore, the section designs an expansive soil soaking test and a pile foundation static load test respectively according to the load transfer rule of a single pile in the expansive soil foundation and the characteristic of water sensitivity of expansive soil. The test scheme is divided into 2 groups, and 4 single piles are designed, namely 2 vertical load-bearing single piles and 2 horizontal load-bearing single piles. The first group tests the vertical limit bearing capacity before and after the vertical loaded single pile is soaked in water, the second group tests the horizontal limit bearing capacity before and after the horizontal loaded single pile is soaked in water, and the test groups are shown in table 2. Through model test, the law of change of uplift and pile body internal force of a single pile in the process of soaking is researched, the bearing characteristics of the single pile before and after the expansive soil is soaked are contrastively analyzed, and test basis is provided for design and subsequent theoretical analysis of a pile foundation in the expansive soil.
TABLE 2 test grouping
During the test, the water is added into the bucket, and the water level is continuously controlled to be consistent with the high layer of the soil surface, so that the full-soaking expansion effect of the expansive soil is realized, and the purpose of simulating the expansion characteristic of the expansive soil is achieved. And measuring the uplift amount of the pile top and the soil surface by a dial indicator in the process of soaking. According to the experience of previous experiments, the uplift quantity of the pile top and the soil surface at the initial stage of water immersion changes more severely, so that the reading frequency is designed to be 1 time/h. The amount of swelling gradually stabilized with time, and the frequency of readings was suitably reduced to 1/6 h. In addition, the axial force change of the pile body in the process of soaking is measured through a static strain tester. And connecting each pile wire and the temperature compensation sheet with a strain gauge, then connecting the static strain gauge to a computer, and setting the acquisition interval to be 3600s (namely 1h) once. And when the dial indicator reading and the data of the strain gauge tend to be stable and no obvious fluctuation exists within 48 hours, the soaking test is finished. This test was soaked for 14 days. Since the static load test is carried out on the piles No. 1 and No. 3 before the soaking, only the uplift amount and the internal force change of the pile tops and the ground surface of the piles No. 2 and No. 4 are measured in the soaking process.
(1) Vertical static load test
And (3) carrying out a graded loading test on the model pile before and after soaking by adopting an independently developed vertical loading system, and establishing a Q-s curve of the model pile so as to determine the vertical ultimate bearing capacity of the model pile. In the loading process, a static strain tester is used for automatically acquiring the strain of the pile body, a dial indicator is arranged on the pile cap for measuring the settlement of the pile top, and a force sensor is arranged between the pile top and the jack for recording the data of the loading stage. The test procedure is as follows:
① preparing for the loading reaction frame to be placed on the model box, installing jacks, adjusting the positions of the reaction frame and the jacks to ensure the loading direction to be consistent with the axial lead of the model pile, and then mechanically fixing the model box by the G-shaped clamp.
② installation instrument, in order to ensure the vertical load born by the model pile to be consistent with the axis, the pile cap, the force sensor and the spherical hinge are respectively arranged above the pile top, the pile cap top is provided with a dial indicator for measuring the settlement of the pile top, the bottom of the self-developed pile cap is embedded into the pile top, the top is provided with a bolt hole and is mechanically fixed with the force sensor through a bolt, the force sensor is ensured not to generate displacement in the horizontal direction, the force sensor is also fixed with the spherical hinge through a bolt, and the jack is contacted with the spherical hinge through a hemisphere welded at the top to carry out graded loading on the model pile.
③, vertical loading and data recording, namely, utilizing a jack to carry out vertical grading loading on the model pile, and recording the load size and the pile top settlement of each grade of loading, when the pile body strain value and the settlement of each grade of loading are stable, carrying out next grade of loading, and when the pile top settlement is sharply increased in certain grade of loading, stopping the loading.
④, data arrangement, namely arranging the recorded test data, calculating and correcting the pile body strain value to obtain the pile side axial force, the pile side frictional resistance and the like, and obtaining the model pile Q-s curve by combining the pile top load and the settlement.
Horizontal static load test
And (3) carrying out a graded loading test on the model pile before and after soaking by adopting an independently developed horizontal loading system, and establishing a p-y curve of the model pile so as to determine the horizontal ultimate bearing capacity of the model pile. In the loading process, a static strain tester is used for automatically acquiring the strain of the pile body, 2 dial indicators are arranged at the loading point of the pile top and the soil surface for measuring the horizontal displacement of the pile top, and a force sensor is arranged between the pile top and the iron hanging basket for recording the loading stage data. The test procedure is as follows:
① the loading reaction frame is put on the model box and the pulley is adjusted to ensure the loading direction is horizontal, the steel strand is passed through the preset round hole on the pile top and connected with the force sensor, the other end of the sensor is also bound with the steel strand and passed through the pulley and matched with the iron hanging basket for loading, after that, the reaction frame and the model box are fixed mechanically by the G-shaped clamp.
② installing instruments, 2 dial indicators are installed at the pile top loading point and the soil surface for measuring the horizontal displacement of the pile top.
③, horizontally loading and recording data, namely, horizontally loading the model pile in a grading manner by adding a heavy object into the iron hanging basket, and recording the load size and the pile top horizontal displacement of each grade of loading, when the strain value and the displacement of the pile body of each grade of loading are stable, loading the next grade, and when the displacement is sharply increased in certain grade of loading, stopping loading.
④, arranging the recorded test data, obtaining pile body bending moment through the measured pile body strain value, and obtaining pile side soil resistance and pile body horizontal displacement through formula fitting calculation, thereby obtaining a model pile p-y curve in the expansive soil foundation.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, a plurality of modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (10)
1. The utility model provides a but multidirectional loaded inflation soil pile base experimental apparatus which characterized in that: comprises a water tank (1), a water inlet connecting pipe (1.1), a box body (2), a gravel layer (3), a coarse sand layer (4), a fine sand layer (5), an expansive soil foundation (6), a water soaking pipe (7), a model pile (8) and a strain gage (9);
water tank (1) is through the bottom intercommunication of water inlet connecting pipe (1.1) and box (2), gravel layer (3) are placed in box (2) bottom, gravel layer (3) set up the upper end in gravel layer (3), fine sand layer (5) set up the upper end in coarse sand layer (4), bloated soil foundation (6) set up on fine sand layer (5), inside immersion pipe (7) inserted box (2), bottom and gravel layer (3) intercommunication, top protrusion bloated soil foundation (6) surface, in bloated soil foundation (6) was inserted in model pile (8), and the top exposed bloated soil foundation (6) surface, strain gauge (9) set up on the side of model pile (8), and draw forth outside strain tester through the wire and connect.
2. The expansive soil pile foundation experimental device capable of being loaded in multiple directions as claimed in claim 1, wherein: the side of box (2) is provided with hypotenuse support frame (2.1), is provided with spout (2.2) on hypotenuse support frame (2.1), and the side of spout (2.2) is provided with the fixed orifices.
3. The expansive soil pile foundation experimental device capable of being loaded in multiple directions as claimed in claim 2, wherein: the box is characterized in that a reaction frame (10) is arranged on the sliding groove (2.2), a transverse shifting plate is arranged at the top end of the reaction frame (10), a jack (11) is arranged on the transverse shifting plate, one side of the reaction frame (10) is arranged in the sliding groove (2.2) at the front end of the box body (2), and the other side of the reaction frame is arranged in the sliding groove (2.2) at the rear end.
4. The expansive soil pile foundation experimental device capable of being loaded in multiple directions as claimed in claim 3, wherein: still include ball pivot (12), force sensor (13) and pile cap (14), pile cap (14) are detained at model stake (8) top, force sensor (13) set up on pile cap (14), ball pivot (12) set up the top at force sensor (13), ball pivot (12) top is provided with spherical groove, force sensor (13) are connected with outside strain test appearance, the flexible bottom and the contact of ball pivot (12) of jack (11) are connected.
5. The expansive soil pile foundation experimental device capable of being loaded in multiple directions as claimed in claim 2, wherein: the loading frame is characterized in that a loading frame (15) is arranged on the sliding groove (2.2), one side of the loading frame (15) is arranged in the sliding groove (2.2) on the left side of the box body (2), the other side of the loading frame is arranged in the sliding groove (2.2) on the right side, a pulley (17) is arranged on the loading frame (15), a transverse force sensor (16) and an iron frame (18) are arranged on the loading frame (15), the iron frame (18) penetrates through the pulley (17) through a steel wire rope and is connected with the top of the model pile (8) through the transverse force sensor (16), a weighting block is placed on the iron frame (18), and the steel wire ropes on the two sides of the pulley (17) form a.
6. The expansive soil pile foundation experimental device capable of being loaded in multiple directions as claimed in claim 2, wherein: still include loading mound (21), stake raft (22) and soil moisture sensor (23), stake raft (22) set up on bloated soil foundation (6) surface, stake raft (22) bottom is provided with model stake (8) that a plurality of equidistant settings, and stake raft (22) are fixed to be set up on the model stake (8) that a plurality of equidistant settings, loading mound (21) set up on stake raft (22), soil moisture sensor (23) set up in bloated soil foundation (6) of model stake (8) side that a plurality of equidistant settings, and soil moisture sensor (23) are connected with outside computer or host computer display screen through the wire.
7. The expansive soil pile foundation experimental device capable of being loaded in multiple directions as claimed in claim 3, wherein: still include vertical displacement meter (19) and vertical load case (20), vertical displacement meter (19) is vertical to be set up on loading mound (21), vertical load case (20) set up on loading mound (21), the flexible bottom of jack (11) is connected with the top of vertical load case (20).
8. The expanded soil pile foundation experimental device capable of being loaded in multiple directions as claimed in claim 5, wherein: the device is characterized by further comprising a transverse displacement meter (24) and a transverse load box (25), wherein the iron frame (18) penetrates through the pulley (17) through a steel wire rope and is connected with the top of the loading pier (21) through the transverse load box (25), and the transverse displacement meter (24) is transversely arranged on the side edge of the loading pier (21).
9. The expansive soil pile foundation experimental device capable of being loaded in multiple directions as claimed in claim 3, wherein: the three-degree-of-freedom loading device (26) comprises a degree-of-freedom vertical supporting plate (26.1), a degree-of-freedom vertical displacement meter (26.2), a degree-of-freedom horizontal displacement meter (26.3), a degree-of-freedom horizontal supporting plate (26.4), a degree-of-freedom deviation displacement meter (26.5), a degree-of-freedom stress rod (26.6), a degree-of-freedom horizontal fixing plate (26.7), a degree-of-freedom pressure arc frame (26.8), a degree-of-freedom loading box (26.9) and a degree-of-freedom vertical fixing plate (26.10), the top end of the degree-of-freedom vertical supporting plate (26.1) is fixed on a jack (11) on a reaction frame (10), the degree-of-freedom vertical fixing plate (26.10) is fixed on the degree-of-freedom vertical supporting plate (26.1), the degree-of-freedom vertical displacement meter (26.2) is vertically arranged on the degree-of-freedom vertical fixing plate (26.10), and the degree-of-freedom horizontal supporting, the freedom degree transverse fixing plate (26.7) is fixedly arranged on the freedom degree transverse supporting plate (26.4), the freedom degree transverse displacement meter (26.3) is transversely fixed on the freedom degree transverse fixing plate (26.7), the freedom degree pressure arc-shaped frame (26.8) is arranged in the freedom degree transverse fixing plate (26.7), the freedom degree loading box (26.9) is arranged on the loading pier (21), one end of the freedom degree stress rod (26.6) is arranged at the top of the freedom degree loading box (26.9), and the top end of the freedom degree stress arc-shaped frame (26.8) is vertically in contact connection with and arranged on the freedom degree pressure arc-shaped frame.
10. The expansive soil pile foundation experimental device capable of being loaded in multiple directions as claimed in claim 6, wherein: be provided with connecting piece (27) between stake raft (22) and model pile (8), connecting piece (27) are including endotheca bonding section (27.1), linkage segment (27.2) and screw thread section (27.4), endotheca bonding section (27.1), linkage segment (27.2) and screw thread section (27.4) once fixed connection, in interior cover bonding section (27.1) embolias model pile (8), and adhesive connection, linkage segment (27.2) side upper end is provided with wire outlet raft (27.3), be provided with on stake raft (22) and pass hole and wire outlet, the hole that passes of stake raft (22) is passed in linkage segment (27.2), and the wire is drawn forth from wire outlet hole (27.3) and wire outlet, set up screw (27.5) threaded connection on screw thread section (27.4), tighten stake raft (22).
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921364477.2U CN210917492U (en) | 2019-08-21 | 2019-08-21 | Multidirectional-loading expansive soil pile foundation experimental device |
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| CN201921364477.2U CN210917492U (en) | 2019-08-21 | 2019-08-21 | Multidirectional-loading expansive soil pile foundation experimental device |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110439043A (en) * | 2019-08-21 | 2019-11-12 | 广西瑞宇建筑科技有限公司 | It is a kind of can multidirectional load swelled ground pile foundation experimental provision |
| CN117973159A (en) * | 2024-04-01 | 2024-05-03 | 中交(天津)轨道交通投资建设有限公司 | Method and system for analyzing supporting stress characteristics of foundation pit precast pile |
-
2019
- 2019-08-21 CN CN201921364477.2U patent/CN210917492U/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110439043A (en) * | 2019-08-21 | 2019-11-12 | 广西瑞宇建筑科技有限公司 | It is a kind of can multidirectional load swelled ground pile foundation experimental provision |
| CN117973159A (en) * | 2024-04-01 | 2024-05-03 | 中交(天津)轨道交通投资建设有限公司 | Method and system for analyzing supporting stress characteristics of foundation pit precast pile |
| CN117973159B (en) * | 2024-04-01 | 2024-06-11 | 中交(天津)轨道交通投资建设有限公司 | Method and system for analyzing supporting stress characteristics of foundation pit precast pile |
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