CN115094959B - Horizontal simulation test device and method for side friction resistance of concrete pile - Google Patents
Horizontal simulation test device and method for side friction resistance of concrete pile Download PDFInfo
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- CN115094959B CN115094959B CN202210722095.2A CN202210722095A CN115094959B CN 115094959 B CN115094959 B CN 115094959B CN 202210722095 A CN202210722095 A CN 202210722095A CN 115094959 B CN115094959 B CN 115094959B
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Abstract
The application discloses a method for preparing a high-performance liquid crystal display (1: 1 or a device for testing a concrete pile model scaled in equal proportion, wherein the concrete pile side friction resistance horizontal simulation test device is carried out in a horizontal state, solves the problems and risks existing in the prior vertical structure, such as height, installation and debugging, and is developed by the device, and comprises a steel shell structure, a pile soil filling body, a pressure chamber loading mechanism, a hydraulic loading mechanism and a data acquisition system, wherein the data acquisition system is used for acquiring stress temperature, humidity, stress and displacement data, dynamically adjusting and dynamically simulating pile environments (including temperature, humidity, soil layer pressure and soil texture simulation) in the experimental process, and realizing the situation of simulating pile side friction resistance of pile surrounding soil stress states under different loading conditions and obtaining related data.
Description
Technical Field
The application relates to a device and a method for testing side friction resistance of a concrete pile in a laboratory scene, in particular to a test device which has a horizontal structure and can meet the verification of an equal-proportion test model.
Background
In the current pile foundation side friction resistance design manual, the limit side friction resistance empirical value of a single pile is given according to the compaction and hardness degree of a soil layer, the given side friction resistance value is generally a fixed value, and the fixed value is referential. A model and a simulation device for carrying out equal proportion on a single concrete pile are not advanced at present. For this reason, the length of the concrete pile is generally large, the short pile is generally not less than 5 m, and the long pile is arranged in tens of m to form an ultra-long pile of tens of m, so that the simulation device is not available in scientific research institutions.
In view of the foregoing, there is a need for a test apparatus that allows for simulation of concrete piles that can be deployed in a laboratory and scaled equally, whether based on engineering practices or based on test acquisition and improvement.
For this problem, the applicant developed an active technical background investigation with the following findings:
1. by adopting a vertical structure test, the structure is feasible for building short piles, but is not applicable for long piles, and the reason is that the height is too large, so that potential safety hazards exist. For example, CN207959298U discloses a slide-resistant pile model test device, in which a pile is placed in a model box, the model box is a rigid rectangular box with no cover and bottom, and is formed by horizontally sliding and connecting an upper box body and a lower box body, so that a vertical structure model is formed; the inner cavity of the lower box body is filled with sliding bed materials, and the upper box body is filled with sliding mass materials.
2. The soil sample can not be compacted and reinforced, and the laboratory is difficult to simulate the pressure in the actual soil layer. For example, CN113865990a discloses a device for simulating a drawing test of a concrete pile in a frozen soil layer, which comprises a test box body, a refrigerating system, a drawing system, a measuring system and an information acquisition system; the measuring system comprises a displacement sensor, a sensor limiting plate and a steel graduated scale; the test box body is installed on the ground through the outer frame, and the soil layer can not simulate actual soil layer pressure, so that the compactness of the test box body can not be ensured, and the test box body is far away from the engineering reality.
Disclosure of Invention
The object of the present application is to provide a method for the production of a metal alloy with the following characteristics 1:1 or a concrete pile model scaled in equal proportion, the horizontal simulation test device for the side friction resistance of the concrete pile is carried out in a horizontal state, solves the problems and risks existing in the height, installation and debugging of the existing vertical structure, and adopts the developed side friction resistance test method for the pile, in the experimental process, the dynamic adjustment and the dynamic simulation of the pile environment (including but not limited to temperature, humidity, soil layer pressure and soil texture simulation) can be carried out, the situation of simulating the pile side friction resistance of the surrounding soil stress state of the pile under different loading conditions is realized, and relevant data are obtained.
The technical scheme adopted by the application for achieving the purpose is as follows:
the utility model provides a horizontal analogue test device of concrete pile side friction, includes steel shell structure, stake soil packing body, pressure chamber loading mechanism and hydraulic loading mechanism, data acquisition system, wherein, data acquisition system is used for gathering stress temperature, humidity, stress, displacement data, its characterized in that:
the steel shell structure is an openable steel cylinder formed by enclosing a main shell and an auxiliary shell, rib plates are arranged on the inner surface and the outer surface of the main shell and the auxiliary shell, one end part of the main shell is hinged and movably installed on an installation foundation through a steel pin, and the other end of the main shell is in a free opened and closed state; a plurality of buckling installation points which are buckled and installed are also arranged between the installation bases of the main shell; the steel shell structure adjusts the inclination angle along the hinging point, and the power component for adjusting the inclination angle is a hydraulic jack I;
a flange cover is fixed at the bottom end of the steel cylinder, an annular flange is arranged at the top end of the steel cylinder, a hydraulic jack II is fixedly arranged at the inner side of the flange cover, a sliding column is fixedly arranged at the other end of the hydraulic jack II, the sliding column is a cylinder and is attached to the inner wall of the steel cylinder in a sliding fit manner, and under the action of the hydraulic jack II, the sliding column has a sliding action, and the maximum stroke of the sliding column is not less than 20 cm; the annular flange consists of two semi-annular rings, the outer edges of the annular flange are fastened by high-strength screws, and the inner side of the annular flange is provided with a rubber ring and is matched with the neck of the pile body through the rubber ring;
the top of the pile body is matched with a hydraulic loading mechanism, and the hydraulic loading mechanism is used for loading the pile body in a pressing and pulling manner;
filling a pile soil filling body in a space between the pile body and the steel cylinder;
the pressure chamber loading mechanism comprises fine sand, a loading plug and an embedded pressure sensor, the fine sand is in a dry state, and the fine sand is filled from a filling opening on the main shell or the auxiliary shell and is filled into a gap between the steel shell and the pile body filling body under the action of the loading plug.
The data acquisition mechanism comprises jack pressure gauges, pressure sensors, data transmission lines, a data receiving processor, a displacement meter, a temperature sensor, a humidity sensor, a strain sensor and a singlechip, wherein the jack pressure gauges are arranged on each hydraulic jack and are used for monitoring hydraulic pressure values; the displacement meter monitors and obtains top displacement data of the pile body under the action of external loading force; the strain gauges are stuck in groups from the bottom of the pile body at equal intervals upwards, three strain gauges with the same structure are stuck on each layer, data output contacts of the strain gauges are welded by copper wires and extend to a resistance strain gauge connected with the singlechip, and strain data are acquired and obtained; the temperature sensor, the humidity sensor and the pressure sensor are arranged inside the pile soil filling body, are arranged at multiple points and are connected with the singlechip through the data transmission line.
The displacement meter adopts a displacement sensor, the bottom end of the displacement sensor is fixed on a cross beam of the hydraulic loading mechanism by adopting a matched screw and a fixed bracket, and the tie rod end of the displacement sensor is inserted into and fixed on a basic marker post.
The pressure sensor is pre-buried in a fine sand layer or a pile soil layer.
The hydraulic loading mechanism comprises a cross beam, mounting brackets and hydraulic jacks III, wherein the number of the hydraulic jacks III is two, the cross beam is respectively supported from two sides in a left-right mode, the other end of the hydraulic jack III is fixed on the mounting brackets, and the middle part of the cross beam is fixedly connected with a pile head of the pile body.
The loading plug adopts a threaded plunger.
The loading plug adopts hydraulic loading.
The pressure chamber loading mechanism is a plurality of spiral sand feeders arranged on the steel shell.
And the vibrator is fixed on the outer wall of the steel cylinder.
The rib plate on the inner surface of the steel cylinder is an annular or spiral rib plate with the height within 50 mm, and is welded and fixed.
The hinged installation end of the main shell is cylindrical, the rest part is a half arc plate, the auxiliary shell is a half arc plate, and the main shell and the auxiliary shell are connected in a packaged mode through a plurality of high-strength bolts.
The horizontal simulation test method for the side friction resistance of the concrete pile comprises the following steps:
firstly, filling a sand-stone soil sample in a main shell of a cylinder, wherein the sand-stone soil sample is obtained by mining from a construction site, spraying water according to requirements in the filling process, filling water layer by layer, scraping redundant sand by using a modeling scraping plate, rolling along the axial direction by using a rolling device to form a groove for placing a pile body, in the process, embedding a temperature sensor, a humidity sensor and a pressure sensor in the sand stone, leading out a steel cylinder through a data wire, connecting the steel cylinder with a data acquisition module through a data interface, sleeving a rubber ring on the neck of the pile body in advance, fixing a half annular flange, placing the pile body in the groove and clamping the pile body at the top end of the main shell by the annular flange when in installation, and positioning, wherein the leakage length of the pile body is not less than 40 cm;
the strain gages are adhered in groups from the bottom of the pile body at equal intervals upwards, three strain gages with the same structure are adhered on each layer, sand and soil samples are covered around the pile body, preliminary tamping or rolling is carried out, and the compactness of the soil samples around the pile body is improved;
installing and positioning a pile body, namely, after the position is adjusted, closing an auxiliary shell, closing two annular flanges, closing a main shell and the auxiliary shell by using a high-strength bolt assembly, fixing the annular flanges and the auxiliary shell, and then injecting a dry sand and soil sample into a filling window on the auxiliary shell;
thirdly, jacking the steel shell cylinder body by a certain inclined included angle by utilizing a hydraulic jack I, conveying dry fine sand into the shell body, vibrating the outer wall of the cylinder body by utilizing a vibrator in the filling process, plugging a sand filling port after the cylinder body is full, wherein the fine sand is dry fine sand, and fully filling the fine sand by vibrating the vibrator;
step four, axially pressurizing by using a hydraulic jack II at the bottom to enable the sand and soil sample to be compact in the axial direction, vibrating the outer wall of the cylinder by using a vibrator when the hydraulic jack reaches the set 20Mpa, then releasing the pressure, pressurizing for a plurality of times, and maintaining the pressure and standing after meeting the requirement to enable the sand and soil sample to keep the pressure;
step five, screwing the high-strength bolt into the steel cylinder by using the high-strength bolt, and integrally rotating the steel cylinder by 90 degrees to adjust the steel cylinder from an inclined state to a horizontal state;
step six, loading test, namely slowly pressurizing a main hydraulic pump of the hydraulic loading mechanism, observing the reading of a hydraulic meter, and repeatedly adjusting until the reading simultaneously reaches the preset compressive stress and keeps stable; and (3) observing the readings of the displacement meter in real time, and reading the numbers of the jack pressure meter, the displacement meter and the pressure meter once every 0.4mm of change until the number of the displacement meter exceeds 6mm, and completing the test.
Through the design scheme, the application has the following beneficial effects:
the test device and the test method adopt a model mode of scaling in equal proportion to build a model, and various factors such as the property, depth, humidity and temperature of soil layers around the pile are adjusted and replaced, so that the pile model can be manufactured aiming at engineering practice, and the test is developed, so that obtained data are more real and effective, and the engineering practice is met.
The horizontal structure converts the adverse factors of the height of the pile body into horizontal length to form the beneficial factors, and adopts a mode of obliquely manufacturing samples and horizontally loading to carry out a loading test, so that the pile body engineering data simulation of any length and diameter can be satisfied.
The application can give accurate side friction resistance value before the design stage by modeling and verifying by adopting an equal-proportion scaling model, provides reliable design parameter basis for engineering design, has data close to engineering practice, and can be used for guiding engineering design and construction.
Drawings
The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the principles of the application:
FIG. 1 is a block diagram of a pile side frictional resistance test apparatus according to the present application.
Fig. 2 is one of the loading test charts.
Fig. 3 is one of the loading test charts.
Fig. 4 is a top view of fig. 3.
Fig. 5 is a process step one of the implementation.
Fig. 6 shows a second embodiment of the process.
Fig. 7 shows a third embodiment of the process.
Fig. 8 shows a fourth embodiment of the process.
Fig. 9 is a partial cross-sectional view of the top end of the steel cylinder.
Detailed Description
In order to more clearly illustrate the present application, the present application will be further described with reference to preferred embodiments and the accompanying drawings.
The working principle of the test device is that a horizontal type device is manufactured, the defects of a vertical type device are changed, the horizontal type state is used for simulating and verifying the actual stress state, the humidity state, the temperature state and other comprehensive environmental factors in concrete piles and surrounding soil layers of the concrete piles as research purposes, the pile body performance in specific environments in different projects is simulated through sample soil collection, filling and tamping of engineering places, the side friction resistance of the pile body is measured and obtained through internal stress loading, and the test device and the test method for simulating the pile side friction resistance of a certain soil layer at any depth are particularly suitable for pile body models with the same proportion as 1:1.
The pile side friction resistance measured through the device is more fit with engineering reality, data can be directly used without calculation and correction, the problem of reasonable value of pile foundation side friction resistance in the existing engineering practice design is solved, and an important parameter basis is provided for the pile foundation engineering design of pile side friction resistance value.
The application has the working principle that the application aims at quantitatively researching the actual stress state of the surrounding soil of the pile in the stratum, and the pile body performance under specific environment is realized through different soil, different internal stress loading data and different humiture. And (3) performing pile body side friction resistance unfolding tests on different soil samples and different internal stress data, collecting and sorting the data to form a data sample library, and providing important parameter basis for pile body side friction resistance value of pile foundation engineering design.
The following description, which is intended to be limited and discussed in connection with several specific embodiments, is presented in conjunction with fig. 1 through 9 to facilitate understanding.
Example 1 of test device
This analogue test device includes: the pile-soil filling device comprises a steel shell structure 100, a pile-soil filling body 200, a pressure chamber loading mechanism 300, a hydraulic loading mechanism 400 and a data acquisition system, wherein the data acquisition system is used for acquiring stress temperature, humidity, stress and other data and converting engineering analog data into digital data.
The main body structure adopts a steel shell, namely a steel structure. Specifically, the steel shell structure 100 is a mounting base of other mechanisms, and is also a shell for bearing the expansion force of the filler, and is preferably made of a thick steel plate with the thickness not less than 20 mm.
The steel shell is a steel cylinder formed by encircling the main shell and the auxiliary shell, rib plates are arranged on the inner surface and the outer surface, the rib plates are annular and are welded and fixed, and the existence of the rib plates can improve the circumferential annular rigidity of the steel shell. Meanwhile, the rib plate on the inner surface has the height of less than 50 mm, and plays a role and an effect of mutual engagement with the inner filler, namely, the anchoring force of the inner filler (sand, plain soil and the like) and the inner wall of the steel shell is improved.
The installation basis adopts the multiple spot reinforcing bar to mix earth to pour the body, and this installation basis sets up articulated mounting point and buckle mounting point that carries out fixed mounting to foretell steel casing. Specifically, the hinged mounting point 110 and the buckle mounting point 120 are mounted on the reinforced concrete foundation through foundation bolts, shear bolts and the like, wherein a mounting foundation is formed after the base is mounted, one end of the cylinder is hinged with the hinged mounting point, the other end of the cylinder is in a free opening and closing state, the inclination angle can be adjusted along the hinged point, namely, the cylinder can be inclined and can be horizontal, the state is switched through the lifting jack I, the lower end of the lifting jack I is hinged to be mounted in a ground groove, the number of the lifting jack I is two, and the lifting jack I acts synchronously, so that the lifting stability is kept. After the steel cylinder is leveled, the steel cylinder side buckle is matched with the clamping groove on the supporting pad seat, and the steel cylinder is locked by using the locking device. Specifically, after the snap-in port, it is locked with a jack bolt to ensure sufficient stability.
And a pair of lifting jacks I are arranged between the steel cylinder and the foundation, and the hydraulic jacks I act on the middle position. Through the structure, the conversion between the vertical filling state and the horizontal drawing experimental state of the steel cylinder is realized, wherein the steel cylinder is used for placing the concrete pile and filling and tamping the soil sample in an inclined state.
The steel cylinder consists of a main shell and an auxiliary shell, wherein the hinged installation end of the main shell is cylindrical, the rest part of the main shell is a half arc plate, the auxiliary shell is a half arc plate, and the main shell and the auxiliary shell are connected in a sealing way through a plurality of high-strength bolts. After the two shells are fixed, a complete closed space is formed, that is, the main shell and the auxiliary shell are enclosed together to form a steel cylinder. The soil sample filling and manufacturing device has the advantages of being convenient for filling and manufacturing soil samples, being convenient for installing and pasting various sensors and meeting engineering actual requirements.
The bottom of the steel cylinder is provided with a totally-enclosed flange cover 130 which is fixed at the lower end of the steel cylinder by welding around to form a closed bottom. The flange cover is drilled and a high-strength bolt is used for installing a hydraulic jack II, namely, a cylinder body of the hydraulic jack II is fixed on the flange cover. The piston of the hydraulic jack II is fixedly connected with a sliding column. The sliding column is a cylinder, is attached to the inner wall of the steel cylinder and is in sliding fit with the inner wall of the steel cylinder, namely, under the action of a hydraulic jack, the sliding column has a sliding distance and a sliding action in the axial direction, the maximum stroke of the sliding column is about 30 cm, the sliding column has the function of axially pressurizing a soil layer filled in the sliding column, and the compactness of a soil layer sample is close to the actual environment of a piling position in a construction site. The hydraulic jack has the function of compacting the soil layer filled with sand and plain soil in the last step, and meets the field simulation requirement of engineering.
The top of the steel cylinder is provided with an open annular flange 140, the annular neck of which is provided with a structure in active fit with the pile body, in particular the annular flange is composed of two semi-annular rings, i.e. the two semi-annular rings form a ring by means of assembly. The assembly structure can effectively buckle and fix the rubber ring in the annular flange. The two annular flanges are fastened with the main shell and the auxiliary shell of the steel cylinder by adopting rigid screws, so that the shearing resistance in the axial direction is formed. That is, the annular flange is fixed to the free end of the steel cylinder, which corresponds to the above-mentioned hinged end.
The top of the pile body 00 is matched with the hydraulic loading mechanism, different hydraulic loading mechanisms are adopted for the tensile test and the compression test, and the pile body is loaded by pressing and pulling through the hydraulic loading mechanism and directly acting on the pile top.
And a rubber ring is attached to the annular flange for forming dynamic seal aiming at the error of the concrete pile, so that the filling materials such as sand, plain soil and the like in the annular flange are prevented from flowing out in the pressurizing process.
Wherein the pile soil packing 200 is used to simulate natural environments in different soil layer soil properties (density, composition, etc.), different soil layer depths, such as loose sand soil layer, clay soil layer, gravel soil layer, frozen soil layer, and develop quantitative or qualitative studies.
The hydraulic loading mechanism comprises two structures, namely a tensile test of the structure, and comprises a cross beam, mounting brackets and hydraulic jacks, wherein the number of the hydraulic jacks is two, the cross beam is respectively supported from two sides in a left-right mode, the other end of each hydraulic jack is fixed on the mounting bracket, the middle part of the cross beam is fixedly connected with a pile head of a pile body, and the pile head is reliably connected with the pile head. The specific structure is shown in the specific embodiment.
For example, a connection structure of pile head and crossbeam, this connection structure includes the built-in fitting of pre-buried in the pile head, carries out quick, firm connection through high strength bolt between this built-in fitting and the aforesaid crossbeam for form complete connection between crossbeam and the pile head, expand or press or draw the loading force test to the pile body through foretell hydraulic jack.
The pressure chamber loading mechanism comprises fine sand filler, loading plugs and an embedded pressure sensor, wherein the fine sand is in a dry state, has good fluidity, is filled in a steel cylinder, and is compacted as much as possible in the filling process. The embedded pressure sensor is embedded in the sandy soil layer or the pile soil layer, for example, a sensor is stuck on the inner surface of the steel cylinder and used for collecting the internal pressure of the sandy soil or the pile soil, the pressure data reflect the pressure value of the periphery of the pile body, and the data are corrected properly.
The loading plug adopts a threaded plunger, namely, sand and soil allowance space is arranged in a mode of arranging a plurality of threaded cylinders on the steel shell in advance, and loading is carried out in a screwing mode. The threaded column casing needs to be densely arranged, and the loading mode is manual loading.
The loading plug can also adopt hydraulic loading, specifically, a piston structure is arranged on the cylinder body of the steel cylinder, a hydraulic jack is correspondingly arranged on the outer side of each piston structure, and the hydraulic jack loads sand and maintains pressure through hydraulic action, so that the loading plug is an automatic loading mode.
In a further scheme, in order to be convenient for fill fine sand to the intracavity, above-mentioned pressure chamber loading mechanism still includes setting up a plurality of spiral sand adder (optional) on the steel casing, and this spiral sand adder is fixed on the steel casing, fills sand in to the steel casing through this sand adder to keep sufficient pressure.
Through the effect of foretell pressure chamber loading mechanism, accomplish the preliminary closely knit extrusion of inside stake soil. By filling the sand, a small amount of gaps between the pile soil and the inner wall of the steel cylinder can be filled by utilizing the fluidity of the sand, and the pile soil can be effectively compacted in the radial direction.
The data acquisition mechanism comprises a jack pressure gauge, a pressure sensor, a data transmission line, a data receiving processor, a displacement meter, a temperature sensor, a humidity sensor, a strain sensor and a singlechip. Wherein, jack manometer installs at every hydraulic jack for monitor hydraulic pressure numerical value.
The displacement meter adopts a displacement sensor, the bottom end of the displacement sensor is fixed on the cross beam of the hydraulic loading mechanism by adopting a matched screw and a fixed bracket, the tie rod end of the displacement sensor is inserted into and fixed on a basic standard rod, the basic standard rod is preferably shared with the installation foundation of the hydraulic jack, and the top end displacement data of the pile body under the action of external loading force can be effectively monitored and obtained through the displacement sensor.
The strain sensor adopts a strain gauge with the model of 50A, a plurality of strain gauges with the same structure are adhered in groups from the bottom surface of the pile body to be tested at intervals of 1 meter up in layers, three strain gauges with the same structure are adhered on each layer, the distance between two adjacent strain gauges with the same structure in each layer is 120 degrees, and the strain gauges are adhered by using 502 glue preferably.
And (3) welding the data output contact of the strain gauge by copper wires and extending the data output contact to be connected with a resistance strain gauge of the singlechip, and acquiring and obtaining strain data. The data is output through the single chip microcomputer and then is output visually.
The data obtained by the singlechip is transmitted to a computer through a data line for subsequent storage and data analysis.
The temperature sensor, the humidity sensor and the pressure sensor are arranged inside the pile surrounding soil sample, the sensors are arranged in multiple points, and the sensors are connected with the singlechip for data receiving and processing through the data transmission line and are used for collecting the internal pressure around the pile body.
The jack pressure gauge is used for monitoring the oil pressure of the jack.
The simulation test method is characterized by adopting the test device to test, and comprises the following steps:
step one, filling half of a sand and soil sample 01 in a main shell of the cylinder, wherein the sand and soil sample is obtained from the exploitation of a construction site so as to be close to the actual engineering, and spraying water according to the requirement in the filling process, so that the humidity of the sand and soil sample meets the set requirement and is close to the hydrological condition of the engineering site as much as possible. The method is carried out by filling layer by layer and spraying water layer by layer so as to ensure the humidity compounding requirement, and a modeling scraping plate is utilized to scrape redundant sand and stone, the modeling scraping plate is provided with an arc-shaped bulge, a groove 02 for placing the pile body is formed by rolling along the axial direction by a rolling device, and the arc radius of the groove formed after rolling is equal to the radius of the pile body so as to complete the anastomotic groove of the pile body. In the process, a temperature sensor, a humidity sensor and a pressure sensor are pre-buried in a sand soil sample, the temperature sensor, the humidity sensor and the pressure sensor are led out of the cylinder body through data lines, the temperature sensor, the humidity sensor and the pressure sensor are connected with a data acquisition module through data interfaces, the pile body 00 is placed in the groove, a rubber ring and a half annular flange are sleeved on the neck of the pile body in advance, the annular flange is clamped in an annular groove of a main shell of the cylinder body as positioning during installation, axial positioning is carried out, high-strength screws are used for fixing, and other half annular flanges are used for fixing, and the two annular flanges are used for clamping the rubber ring. After positioning, the leakage length of the pile body is not less than 40 cm. And a group of strain gages are arranged on the surface of the pile body at intervals of 1 meter, so that the strain gages are fixed, and the strain gages are used for measuring stress data of the pile body.
Covering a certain amount of sand and soil samples around the pile body, and primarily tamping or rolling to improve the compactness of the soil samples around the pile body;
before the pile body is installed, the combination firmness between the pile body and the sand filling body can be effectively improved by spraying concrete slurry on the surface of the pile body, so that the concave-convex combination surface between the pile body and the sand filling body is more similar to engineering practice.
And secondly, mounting and positioning the pile body, wherein the coaxiality of the axis of the pile body 00 and the axis of the steel cylinder is required to be not lower than +/-1 millimeter/hundred meters, after the position is adjusted, closing the auxiliary shell, closing the main shell and the auxiliary shell by using a high-strength bolt assembly, and then injecting dry sand and soil samples into a filling window on the auxiliary shell, wherein the sand and the soil samples are preferably filled, and at the moment, the inner soil samples are partially compact and partially non-compact.
Thirdly, jacking the steel shell cylinder body by using a hydraulic jack to form a certain inclined angle, wherein the inclined angle is about 30 degrees, then conveying dry fine sand 03 into the shell body, vibrating the outer wall of the cylinder body by using a vibrator in the filling process, plugging a sand filling port 04 after the cylinder body is full, and fully filling the fine sand which is dry fine sand by vibrating the vibrator;
and fourthly, axially pressurizing by using a hydraulic jack at the bottom to enable the soil sample to be compact in the axial direction, vibrating the outer wall of the cylinder by using a vibrator when the hydraulic jack reaches the set 20Mpa, then releasing the pressure, pressurizing for a plurality of times, and maintaining the pressure and standing after meeting the requirements to enable the sand and soil sample to be kept.
Specifically, a hydraulic pressurizing device is used for pressurizing the jack, and pressure is maintained after the jack oil gauge reaches the set 20 Mpa;
step five, screwing the high-strength bolt 05 into the interior by using the high-strength bolt, filling and embedding the high-strength bolt into the sand and soil sample, extruding and occupying part of sand and soil sample gaps by using the high-strength bolt, improving the compactness, improving the bonding strength of the sand and soil sample and the steel shell, and integrally rotating for 90 degrees to modify the sand and soil sample from an inclined state to a horizontal state;
step six, loading test, namely slowly pressurizing the main hydraulic pump, observing the reading of the hydraulic meter, and repeatedly adjusting until the reading simultaneously reaches the preset compressive stress and keeps stable; and (3) observing the readings of the displacement meter in real time, and reading the numbers of the jack pressure meter, the displacement meter and the pressure meter once every 0.4mm of change until the number of the displacement meter exceeds 6mm, and completing the test.
The foregoing description is only illustrative of the present application and is not intended to limit the scope of the application, and all equivalent structures or equivalent processes or direct or indirect application in other related technical fields are included in the scope of the present application.
Claims (11)
1. The utility model provides a horizontal analogue test device of concrete pile side friction, includes steel shell structure, stake soil packing body, pressure chamber loading mechanism and hydraulic loading mechanism, data acquisition system, wherein, data acquisition system gathers stress temperature, humidity, stress and displacement data, its characterized in that:
the steel shell structure is an openable steel cylinder formed by enclosing a main shell and an auxiliary shell, rib plates are arranged on the inner surface and the outer surface of the main shell and the auxiliary shell, one end part of the main shell is hinged and movably installed on an installation foundation through a steel pin, and the other end of the main shell is in a free opened and closed state; a plurality of buckling installation points which are buckled and installed are also arranged between the installation bases of the main shell; the steel shell structure adjusts the inclination angle along the hinging point, and the power component for adjusting the angle is a hydraulic jack I;
a flange cover is fixed at the bottom end of the steel cylinder, an annular flange is arranged at the top end of the steel cylinder, a hydraulic jack II is fixedly arranged at the inner side of the flange cover, a sliding column is fixedly arranged at the other end of the hydraulic jack II, the sliding column is a cylinder and is attached to the inner wall of the steel cylinder in a sliding fit manner, and under the action of the hydraulic jack II, the sliding column has a sliding action, and the maximum stroke of the sliding column is not less than 20 cm; the annular flange consists of two semi-annular rings, the outer edges of the annular flange are fastened by high-strength screws, and the inner side of the annular flange is provided with a rubber ring and is matched with the neck of the pile body through the rubber ring;
the top of the pile body is matched with a hydraulic loading mechanism, and the hydraulic loading mechanism is used for loading the pile body in a pressing and pulling manner;
filling a pile soil filling body in a space between the pile body and the steel cylinder;
the pressure chamber loading mechanism comprises fine sand, a loading plug and an embedded pressure sensor, the fine sand is in a dry state, and the fine sand is filled from a filling opening on the main shell or the auxiliary shell and is filled into a gap between the steel shell and the pile body filling body under the action of the loading plug;
the data acquisition mechanism comprises jack pressure gauges, pressure sensors, data transmission lines, a data receiving processor, a displacement meter, a temperature sensor, a humidity sensor, strain gauges and a singlechip, wherein the jack pressure gauges are arranged on each hydraulic jack and are used for monitoring hydraulic pressure values; the displacement meter monitors and obtains top displacement data of the pile body under the action of external loading force; the strain gauges are stuck in groups from the bottom of the pile body at equal intervals upwards, three strain gauges with the same structure are stuck on each layer, data output contacts of the strain gauges are welded by copper wires and extend to a resistance strain gauge connected with the singlechip, and strain data are acquired and obtained; the temperature sensor, the humidity sensor and the pressure sensor are arranged inside the pile soil filling body, are arranged at multiple points and are connected with the singlechip through the data transmission line.
2. The horizontal simulation test device for the side friction resistance of the concrete pile according to claim 1, wherein the displacement meter adopts a displacement sensor, the bottom end of the displacement sensor is fixed on a cross beam of the hydraulic loading mechanism by adopting a matched screw and a fixed bracket, and a tie rod end of the displacement sensor is inserted into and fixed on a basic marker post.
3. The concrete pile side friction horizontal simulation test device according to claim 2, wherein the pressure sensor is pre-buried in a fine sand layer or a pile soil layer.
4. The horizontal simulation test device for the side friction resistance of the concrete pile according to claim 1, wherein the hydraulic loading mechanism comprises a cross beam, mounting brackets and hydraulic jacks III, wherein the number of the hydraulic jacks III is two, the cross beam is supported from two sides by one left hydraulic jack III and the other end of the hydraulic jack III is fixed on the mounting brackets, and the middle part of the cross beam is fixedly connected with the pile head of the pile body.
5. The concrete pile side friction horizontal simulation test device according to claim 4, wherein the loading plug is a threaded plunger.
6. The concrete pile side friction horizontal simulation test device according to claim 4, wherein the loading plug adopts hydraulic loading.
7. The concrete pile side friction horizontal simulation test device according to claim 4, wherein the pressure chamber loading mechanism is a plurality of screw sand feeders arranged on a steel shell.
8. The concrete pile side friction horizontal simulation test device according to claim 4, wherein the vibrator is fixed on the outer wall of the steel cylinder.
9. The horizontal simulation test device for the side friction resistance of the concrete pile according to claim 4, wherein the rib plate on the inner surface of the steel cylinder is an annular or spiral rib plate with the height of less than 50 mm, and the rib plate is welded and fixed.
10. The horizontal simulation test device for the side friction resistance of the concrete pile according to claim 4, wherein the hinged installation end of the main shell is cylindrical, the rest is a half arc plate, the auxiliary shell is a half arc plate, and the main shell and the auxiliary shell are connected in a sealing manner through a plurality of high-strength bolts.
11. A horizontal simulation test method for the side friction of a concrete pile, which is based on the test performed by the test device according to any one of claims 1 to 10, and comprises the following steps:
firstly, filling a sand-stone soil sample in a main shell of a cylinder, wherein the sand-stone soil sample is obtained by mining from a construction site, spraying water according to requirements in the filling process, filling water layer by layer, scraping redundant sand by using a modeling scraping plate, rolling along the axial direction by using a rolling device to form a groove for placing a pile body, in the process, embedding a temperature sensor, a humidity sensor and a pressure sensor in the sand stone, leading out a steel cylinder through a data wire, connecting the steel cylinder with a data acquisition module through a data interface, sleeving a rubber ring on the neck of the pile body in advance, fixing a half annular flange, placing the pile body in the groove and clamping the pile body at the top end of the main shell by the annular flange when in installation, and positioning, wherein the leakage length of the pile body is not less than 40 cm;
the strain gages are adhered in groups from the bottom of the pile body at equal intervals upwards, three strain gages with the same structure are adhered on each layer, sand and soil samples are covered around the pile body, preliminary tamping or rolling is carried out, and the compactness of the soil samples around the pile body is improved;
installing and positioning a pile body, namely, after the position is adjusted, closing an auxiliary shell, closing two annular flanges, closing a main shell and the auxiliary shell by using a high-strength bolt assembly, fixing the annular flanges and the auxiliary shell, and then injecting a dry sand and soil sample into a filling window on the auxiliary shell;
thirdly, jacking the steel shell cylinder body by a certain inclined included angle by utilizing a hydraulic jack I, conveying dry fine sand into the shell body, vibrating the outer wall of the cylinder body by utilizing a vibrator in the filling process, plugging a sand filling port after the cylinder body is full, wherein the fine sand is dry fine sand, and fully filling the fine sand by vibrating the vibrator;
step four, axially pressurizing by using a hydraulic jack II at the bottom to enable the sand and soil sample to be compact in the axial direction, vibrating the outer wall of the cylinder by using a vibrator when the hydraulic jack reaches the set 20Mpa, then releasing the pressure, pressurizing for a plurality of times, and maintaining the pressure and standing after meeting the requirement to enable the sand and soil sample to keep the pressure;
step five, screwing the high-strength bolt into the steel cylinder by using the high-strength bolt, and integrally rotating the steel cylinder by 90 degrees to adjust the steel cylinder from an inclined state to a horizontal state;
step six, loading test, namely slowly pressurizing a main hydraulic pump of the hydraulic loading mechanism, observing the reading of a hydraulic meter, and repeatedly adjusting until the reading simultaneously reaches the preset compressive stress and keeps stable; and (3) observing the readings of the displacement meter in real time, and reading the numbers of the jack pressure meter, the displacement meter and the pressure meter once every 0.4mm of change until the number of the displacement meter exceeds 6mm, and completing the test.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN207959298U (en) * | 2018-02-09 | 2018-10-12 | 西南交通大学 | A kind of friction pile model test apparatus |
| CN110230329A (en) * | 2019-07-12 | 2019-09-13 | 吉林大学 | The pile side friction experimental rig and method of indoor simulation soil around pile stress |
| CN113865990A (en) * | 2021-09-27 | 2021-12-31 | 吉林大学 | Device for simulating drawing test of concrete pile in frozen soil layer |
| WO2022105840A1 (en) * | 2021-11-05 | 2022-05-27 | 中铁四局集团第四工程有限公司 | Test device and method for measuring frictional resistance of thixotropic mud |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN207959298U (en) * | 2018-02-09 | 2018-10-12 | 西南交通大学 | A kind of friction pile model test apparatus |
| CN110230329A (en) * | 2019-07-12 | 2019-09-13 | 吉林大学 | The pile side friction experimental rig and method of indoor simulation soil around pile stress |
| CN113865990A (en) * | 2021-09-27 | 2021-12-31 | 吉林大学 | Device for simulating drawing test of concrete pile in frozen soil layer |
| WO2022105840A1 (en) * | 2021-11-05 | 2022-05-27 | 中铁四局集团第四工程有限公司 | Test device and method for measuring frictional resistance of thixotropic mud |
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