CN111649849A - Combined pile end pressure monitoring device and assembling and testing method thereof - Google Patents

Abstract

The invention discloses a combined pile end pressure monitoring device and an assembling and testing method thereof. The invention can effectively solve the technical problems that the soil pressure box can not be stabilized on the bearing layer of the pile end when the soil pressure box is used for monitoring the pile end pressure in the existing method, the soil pressure box is easy to displace and incline when being under the action of uneven pressure, and the fixing and the protection are improper; the invention can embed a plurality of soil pressure boxes at the pile end, realizes the integral monitoring of the pile end pressure, and solves the problem that the existing pile end pressure monitoring can only embed one soil pressure box and can not accurately reflect the pressure change of the pile end bearing stratum surface.

Description

Combined pile end pressure monitoring device and assembling and testing method thereof

Technical Field

The invention belongs to the technical field of geotechnical engineering, and relates to a pile end pressure monitoring device and a method for a foundation pile, in particular to a combined device for monitoring pile end pressure by using a soil pressure cell and an assembling and testing method thereof.

Background

According to the technical specification for detecting the building pile foundation (JGJ 106-2014), when the design requires or the following conditions occur, the test pile detection is carried out before the construction, and the ultimate bearing capacity of the single pile is determined: firstly, designing a pile foundation with a grade A; a second-grade pile foundation is designed without reference of relevant pile testing data; thirdly, the foundation conditions are complex, and the construction quality reliability of foundation piles is low; fourthly, the pile foundation is formed by adopting a new pile type or a new process in the local area. The pile foundation engineering needs to carry out foundation pile test detection before and after the construction of the engineering pile, and also needs to carry out quality detection and monitoring in the construction process according to the engineering requirement. The foundation pile test is an important basis for evaluating whether the geotechnical engineering foundation is safe and verifying whether the design theory is reasonable. The pile bottom pressure is used as the important content of the foundation pile test, and is the basis for knowing the change process of the pile end resistance and determining the vertical load of the pile top through the interaction of the pile and the soil and achieving the ultimate bearing capacity state.

The pile bottom pressure test is mainly carried out by embedding the soil pressure box at the pile bottom, the vibration string type soil pressure box is most applied at the present stage, and the pile bottom pressure test has the advantages of high sensitivity, high precision, good stability, relatively low price and the like. During testing, the soil pressure box is placed to a required depth for fixed-point monitoring after pre-drilling holes are formed, fine sand is filled in the holes to fill the peripheral space of the soil pressure box, and finally a steel reinforcement cage is placed and concrete is poured. The pile end pressure is transmitted to the contact surface of the soil pressure cell through the fine sand, and the real-time change condition of the pile end pressure is obtained by collecting the vibration frequency change of the vibration string type soil pressure cell.

However, in practical engineering, we find that the existing pile end soil pressure box still has the following problems from installation to measurement: 1. the soil pressure cell is directly arranged on the surface of a bearing layer at the pile end, lacks effective fixing measures and is easy to displace or incline when being acted by uneven pressure; if in the concrete pouring stage, displacement or inclination can occur under the action of uneven pressure of concrete, so that the initial measurement state of the soil pressure cell cannot be ensured, and the pressure and the direction cannot be accurately measured. 2. The existing method only places a soil pressure cell at the center of the pile bottom for measurement, so that the point measurement is realized, and the bearing layer of the pile end is a surface, so that the whole pressure change condition of the bearing layer of the pile end cannot be accurately reflected; especially, when the pressure value test data of the soil pressure cell acted by uneven pressure at the bottom of the pile has larger error, the real and effective pressure value cannot be obtained. 3. The measuring result of the soil pressure box is distorted due to incomplete or excessive compaction of the backfilled fine sand, and when the fine sand is not completely compacted, the pile bottom pressure cannot be effectively transmitted to the soil pressure box by the loose fine sand; when the backfilled fine sand is excessively pressed, the soil pressure box can not detect the smaller pile end pressure; the existing installation method is inconvenient to control the compactness of the backfilled fine sand, and the accuracy of a detection result is influenced. 4. When the pile bottom soil pressure cell is buried by adopting a drilling method, the survival rate of the soil pressure cell buried manually in a narrow field working environment is low, the error is large, the reliability of measured data is difficult to guarantee, the mounting efficiency is low due to a manual operation mode, the soil pressure cell is easy to damage during mounting, and the judgment and evaluation of the accuracy and reliability of a measuring result are influenced.

Disclosure of Invention

Aiming at the technical problems, the invention provides a combined pile end pressure monitoring device and an assembling and testing method thereof, which can effectively solve the technical problems that the prior method has no fixed protection measures on a soil pressure cell when the soil pressure cell is used for monitoring the pile end pressure, the initial measurement state of the soil pressure cell cannot be ensured, the error of the measurement result is large, the precision is low and the like.

The invention is realized by the following technical scheme:

the utility model provides a modular pile tip pressure monitoring device, includes base, coupling assembling, pressure-bearing subassembly and soil pressure cell, its characterized in that: the base comprises a bottom plate and an enclosure cylindrical barrel, wherein a threaded connecting piece I is fixedly connected to the surface of the bottom plate, the enclosure cylindrical barrel is tightly sleeved on the periphery of the bottom plate, the barrel on the upper part of the enclosure cylindrical barrel is higher than the bottom plate and forms a groove body with the bottom plate in an enclosing mode, fine sand is filled in the groove body, and a plurality of soil pressure boxes are uniformly embedded in the fine sand; the connecting assembly comprises a connecting main body arranged above the base, the bottom surface of the connecting main body is in contact with the soil pressure cell, a central hole channel I is arranged in the middle of the connecting main body, a connecting hole channel I matched with the threaded connecting piece I is arranged on the periphery of the central hole channel I, and a threaded connecting piece II is fixedly connected to the periphery of the connecting main body; the pressure bearing assembly comprises a pressure bearing main body, a central duct II corresponding to the central duct I is arranged on the pressure bearing main body, and a connecting duct II matched with the threaded connecting piece II is arranged on the periphery of the central duct II; the threaded connecting piece I penetrates through the connecting pore channel I to fixedly connect the base with the connecting main body, the threaded connecting piece II penetrates through the connecting pore channel II to fixedly connect the connecting main body with the pressure-bearing main body, and the upper end of the pressure-bearing main body is fixedly connected with the foundation pile reinforcement cage; and the soil pressure box is connected with a signal transmission line, and the signal transmission line sequentially passes through the central pore channel I and the central pore channel II, is upwards bound along the foundation pile reinforcement cage and is connected with the ground data acquisition device.

Preferably, at least 4 soil pressure boxes are embedded and uniformly distributed on the same horizontal plane.

Preferably, the middle part of the connecting main body is of a groove type structure, and the central pore channel I and the connecting pore channel I are both arranged in the groove.

Preferably, the base, the connecting assembly and the pressure-bearing assembly are all made of concrete materials.

Preferably, a wrapping casing is arranged on the periphery of the connecting body.

Preferably, the bottom plate, the connecting main body and the pressure-bearing main body are all internally provided with reinforcing ribs, including transverse reinforcing ribs and longitudinal reinforcing ribs which are arranged in a transverse and longitudinal staggered manner.

Preferably, the outer edge of the bottom plate is provided with an anchor bar for fixing the bottom plate and the enclosure cylindrical barrel.

Preferably, the base, the connecting assembly and the pressure-bearing assembly are matched with the pile hole of the foundation pile in shape and size.

An assembling method of a combined pile end pressure monitoring device comprises the following steps,

step one, burying an earth pressure cell: firstly, uniformly embedding a plurality of soil pressure boxes in fine sand of a base, arranging a connecting assembly above the base, connecting and fixing the connecting assembly and the base through a threaded connecting piece and a nut, and horizontally contacting the bottom surface of the connecting assembly with the soil pressure boxes;

step two, calibrating an initial value of the soil pressure cell: the method comprises two steps of rough adjustment and fine adjustment, wherein the rough adjustment enables the initial readings of a plurality of soil pressure boxes to be similar by adjusting the flatness of the fine sand layer; fine adjustment is carried out to ensure that the initial values of a plurality of soil pressure boxes are equal by adjusting the tightness of the threaded connecting pieces and the nuts of the base and the connecting assembly, and initial readings are recorded;

step three, mounting an upper pressure-bearing assembly: the pressure-bearing assembly is arranged above the connecting assembly and is fixedly connected through a threaded connecting piece and a nut, and the upper end of the pressure-bearing assembly is fixedly connected with the foundation pile reinforcement cage; and a signal transmission line of the soil pressure box sequentially penetrates through central pore canals of the connecting component and the pressure-bearing component upwards, and is connected with the data acquisition device after being bound along the foundation pile reinforcement cage.

A test method of a combined pile end pressure monitoring device comprises the following steps,

firstly, pile holes are excavated: excavating a pile hole of the foundation pile according to the embedding depth of the soil pressure box, wherein the bottom of the pile hole is the placement position of the pile end pressure monitoring device;

step two, stably arranging the assembled combined type pile end pressure monitoring device at a preset position at the bottom of a pile hole, pouring concrete into the pile hole to manufacture a foundation pile, and finishing the installation of the combined type pile end pressure monitoring device;

step three, data processing: under the action of pile end pressure, the difference value of the real-time numerical value of each soil pressure box and the initial numerical value of each soil pressure box is a group of pile bottom pressure monitoring data sets, and the average value of each soil pressure box data set is the pile bottom pressure average value; correcting the data, and after eliminating the value which exceeds 25% of the average value of the pile bottom pressure in the measured real-time values, obtaining the corrected data which is the pile end pressure value and is obtained by calculating the average value of the data set again; and drawing the pressure distribution of the pile bottom according to the pressure values of the pile bottom of the soil force box at different embedding depths to obtain the maximum value and the minimum value of the pressure of the pile bottom.

The beneficial effects of the invention different from the prior art are as follows:

1. this combination formula stake end pressure monitoring devices can stabilize the soil pressure cell in the layer of holding power of stake end, has solved soil pressure cell and has easily taken place displacement, slope when receiving inhomogeneous pressure effect, can't guarantee the problem of soil pressure cell initial measuring state, is showing the monitoring precision who has improved stake end pressure.

2. The combined pile end pressure monitoring device can embed a plurality of soil pressure boxes at the pile end, realizes the integral monitoring of the pile end pressure, and solves the problems that the existing pile end pressure monitoring can only embed one soil pressure box and can not accurately reflect the integral pressure change of the pile end holding force layer; the monitoring device can measure the pressure distribution at the bottom of the pile, obtain the maximum value and the minimum value of the pressure and further improve the measurement precision of the pressure at the end of the pile.

3. The soil pressure box is embedded between the bottom plate and the connecting main body to form a whole, so that the disturbance of the pressure box in the installation process is avoided; the connecting assembly plays a role in transferring force, the pressure at the bottom of the pile is uniformly transferred to the pressure box through the pressure bearing assembly, and the groove type structure of the connecting main body reserves enough space for the top of the threaded connecting piece of the base, so that the pressure at the bottom of the pile can be prevented from being shared by the threaded connecting piece after being transferred to the pressure bearing assembly, and enough operating space is reserved for operation; and the pressure-bearing main body and the connecting main body form a box body, so that the box body has higher rigidity, and the pile bottom pressure is accurately transmitted to the pressure box.

4. The problem of low survival rate caused by the fact that the soil pressure cell has no fixed protection measures when the landfill soil pressure cell is installed manually and the signal transmission line of the soil pressure cell is broken is solved; the pile end pressure monitoring device can backfill fine sand outside the pre-drilled hole, so that the compactness of the backfilled fine sand is convenient to control, and the problem that the measurement result of the soil pressure cell is influenced by the compactness of the backfilled fine sand is effectively avoided; the device is suitable for pile holes with large depth, is directly placed in a hoisting or base pile reinforcement cage welding mode, and avoids personal safety hazards when the landfill soil pressure box is manually installed.

5. The pile end pressure monitoring device can be calibrated on the ground, and because the pressure box is fixed in the combined device, the stress working condition is not changed in the process of placing the pressure box into the pile bottom, a calibration curve can be adopted, and the problem that the existing single pressure box without a fixed measure cannot be calibrated after being placed into a pile hole is solved.

6. The whole monitoring device is made of concrete materials, is suitable for monitoring the pile bottom pressure under long-time and corrosive embedding environmental conditions, and can effectively protect the soil pressure cell.

7. The combined pile end pressure monitoring device has the advantages of being simple in structure, easy to manufacture, low in cost and convenient to use on the basis of ensuring accuracy of a measuring result.

Drawings

Fig. 1 is a schematic structural view of a combined pile tip pressure monitoring device according to the present invention;

FIG. 2 is a schematic structural diagram of a base in the combined pile tip pressure monitoring device of the present invention;

FIG. 3 is a top view of FIG. 2;

FIG. 4 is a top view of a bottom plate of the modular pile tip pressure monitoring apparatus of the present invention;

FIG. 5 is a schematic structural diagram of a connecting assembly of the combined pile tip pressure monitoring device of the present invention;

FIG. 6 is a top view of FIG. 5;

fig. 7 is a schematic structural diagram of a pressure-bearing assembly in the combined pile-end pressure monitoring device of the invention;

FIG. 8 is a top view of FIG. 7;

FIG. 9 is a graph of pressure monitoring versus time for an embodiment;

in the figure: 1-bottom plate, 2-enclosing cylindrical barrel, 3-fine sand, 4-soil pressure box, 5-threaded connector I, 6-connecting main body, 7-central pore passage I, 8-connecting pore passage I, 9-threaded connector II, 10-bearing main body, 11-central pore passage II, 12-connecting pore passage II, 13-foundation pile reinforcement cage, 14-signal transmission line, 15-wrapping protective barrel, 16-transverse reinforcing rib, 17-longitudinal reinforcing rib, 18-anchor rib and 19-lifting lug.

Detailed Description

The invention and its effects will be further explained with reference to the drawings and the embodiments.

As shown in fig. 1-8, a combined pile tip pressure monitoring device comprises a base, a connecting assembly, a pressure-bearing assembly and a soil pressure cell, wherein the base comprises a bottom plate 1 and an enclosure cylindrical barrel 2, the enclosure cylindrical barrel 2 is sleeved on the periphery of the bottom plate 1 and is tightly bonded together through a high-strength adhesive, and an anchor bar 18 is further arranged on the periphery of the outer edge of the bottom plate 1 and is used for further fixing the bottom plate 1 and the enclosure cylindrical barrel 2. The upper barrel of the enclosing cylindrical barrel 2 is higher than the bottom plate and forms a groove body with the surface of the bottom plate 1 in an enclosing mode, fine sand is filled in the groove body, a plurality of soil pressure boxes 4 are uniformly embedded in the fine sand 3, at least 4 soil pressure boxes 4 can be embedded, and the soil pressure boxes are uniformly distributed on the same horizontal plane; the surface of the bottom plate 1 is welded with a threaded connecting piece I5 connected with the connecting component. The connecting assembly comprises a connecting main body 6 arranged above the base, the bottom surface of the connecting main body is in contact with the soil pressure cell 4, a central hole channel I7 is arranged in the middle of the connecting main body, and connecting hole channels I8 matched with the threaded connecting piece I5 are uniformly arranged on the periphery of the central hole channel I7; threaded connection pieces II 9 connected with the pressure bearing assembly are welded around the connecting main body 6. The pressure-bearing assembly comprises a pressure-bearing main body 10, wherein a central duct II11 corresponding to the central duct I7 is arranged on the pressure-bearing main body, and a connecting duct II 12 matched with the threaded connecting piece II 9 is arranged on the periphery of the central duct II 11. During assembly, the threaded connecting piece I5 penetrates through the connecting pore channel I8, the base and the connecting main body 6 are fixedly connected through the nut and the gasket, the threaded connecting piece II 9 penetrates through the connecting pore channel II 12, the connecting main body 6 and the pressure-bearing main body 10 are fixedly connected through the nut and the gasket, and the upper end of the pressure-bearing main body 10 is fixedly connected with the foundation pile reinforcement cage 13; the soil pressure box 4 is connected with a signal transmission line 14, and the signal transmission line 14 sequentially penetrates through the central hole channel I7 and the central hole channel II11, is bound upwards to the top end along the foundation pile reinforcement cage 13 and then is connected with an above-ground data acquisition device. The base, the connecting assembly and the pressure-bearing assembly are matched with the pile holes of the foundation piles in shape and size and are made of concrete materials, so that the foundation pile can be suitable for monitoring the pile bottom pressure of a long-time corrosive embedded environment condition, and the soil pressure box can be effectively protected. This combination formula stake end pressure monitoring devices can stabilize the soil pressure cell in the layer of holding power of stake end, has solved soil pressure cell and has easily taken place displacement, slope when receiving inhomogeneous pressure effect, can't guarantee the problem of soil pressure cell initial measuring state, is showing the monitoring precision who has improved stake end pressure. The combined pile end pressure monitoring device can embed a plurality of soil pressure boxes at the pile end, realizes the integral monitoring of the pile end pressure, and solves the problems that the existing pile end pressure monitoring can only embed one soil pressure box and can not accurately reflect the integral pressure change of the pile end holding force layer; the monitoring device can measure the pressure distribution at the bottom of the pile, obtain the maximum value and the minimum value of the pressure and further improve the measurement precision of the pressure at the end of the pile. In addition, the pile end pressure monitoring device can be calibrated on the ground, and because the pressure box is fixed in the combined device, the stress working condition is not changed in the process of placing the pressure box into the pile bottom, a calibration curve can be adopted, and the problem that the existing single pressure box without a fixed measure cannot be calibrated after being placed into a pile hole is solved.

Furthermore, the middle part of the connecting main body 6 is of a groove type structure, and a central pore channel I7 and a connecting pore channel I8 on the connecting main body are both arranged in the groove; the groove type structure reserves enough space for the top of the threaded connecting piece of the base, on one hand, the pressure at the bottom of the pile is prevented from being shared by the threaded connecting piece after being transmitted to the pressure bearing assembly, on the other hand, enough operating space is reserved, and the operation is convenient. The connecting assembly can play a role in transferring force and uniformly transfer the pressure of the pile bottom to the pressure box through the pressure-bearing main body; the pressure-bearing main body and the connecting main body form a box body, so that the box body has higher rigidity, and the pile bottom pressure is accurately transmitted to the pressure box.

Furthermore, the periphery of the connecting main body 6 is provided with a wrapping protective tube 15, so that the connecting main body 6 can be prevented from being corroded, and the service life of the whole device is effectively prolonged. Reinforcing ribs are arranged in the bottom plate 1, the connecting main body 6 and the pressure-bearing main body 10, and comprise transverse reinforcing ribs 16 and longitudinal reinforcing ribs 17 which are arranged in a transverse and longitudinal staggered mode, and the structures of the reinforcing ribs are respectively shown in figures 2-8. In addition, lifting lugs 19 made of bent ribs are further fixedly connected to two sides of the upper end of the pressure-bearing main body 10, and lifting is facilitated.

An assembling method of a combined pile end pressure monitoring device comprises the following steps,

step one, burying an earth pressure cell: firstly, uniformly embedding a plurality of soil pressure boxes 4 in fine sand 3 of a base, arranging a connecting assembly above the base, connecting and fixing the connecting assembly and the base through a threaded connecting piece and a nut, and horizontally contacting the bottom surfaces of the connecting assembly and the soil pressure boxes 4;

step two, calibrating an initial value of the soil pressure cell: the method comprises two steps of rough adjustment and fine adjustment, wherein the rough adjustment enables the initial readings of a plurality of soil pressure boxes to be similar by adjusting the flatness of the layer of fine sand 3; fine adjustment is carried out to ensure that the initial values of a plurality of soil pressure boxes are equal by adjusting the tightness of the threaded connecting pieces and the nuts of the base and the connecting assembly, and initial readings are recorded;

step three, mounting an upper pressure-bearing assembly: the pressure-bearing assembly is arranged above the connecting assembly and is fixedly connected through a threaded connecting piece and a nut, and the upper end of the pressure-bearing assembly is fixedly connected with the foundation pile reinforcement cage 13; the signal transmission line 14 of the soil pressure cell 4 sequentially passes through the central pore canals of the connecting component and the pressure-bearing component upwards, and is connected with the data acquisition device after being bound along the foundation pile reinforcement cage 13.

A test method of a combined pile end pressure monitoring device is characterized in that: comprises the following steps of (a) carrying out,

firstly, pile holes are excavated: excavating a pile hole of the foundation pile according to the embedding depth of the soil pressure box, wherein the bottom of the pile hole is the placement position of the pile end pressure monitoring device;

step two, stably arranging the assembled combined type pile end pressure monitoring device at a preset position at the bottom of a pile hole, pouring concrete into the pile hole to manufacture a foundation pile, and finishing the installation of the combined type pile end pressure monitoring device;

step three, data processing: under the action of pile end pressure, the difference value of the real-time numerical value of each soil pressure box and the initial numerical value of each soil pressure box is a group of pile bottom pressure monitoring data sets, and the average value of each soil pressure box data set is the pile bottom pressure average value; correcting the data, and after eliminating the value which exceeds 25% of the average value of the pile bottom pressure in the measured real-time values, obtaining the corrected data which is the pile end pressure value and is obtained by calculating the average value of the data set again; and drawing the pressure distribution of the pile bottom according to the pressure values of the pile ends of the soil stress box at different embedding depths to obtain the maximum value and the minimum value of the pile bottom pressure.

Examples

This embodiment is foundation pile end pressure load test, buries 4 pressure cells underground in this combination formula pile end pressure monitoring devices for the change condition of monitoring pile end pressure under the different load effect. As can be seen from the pressure monitoring value versus time graph of fig. 9: when the time is 0-25 h, the measured value curves measured by the soil pressure boxes No. 1, No. 2, No. 3 and No. 4 are stable and relatively close, which indicates that the stress of the 4 soil pressure boxes is uniform, and the data set measured by each soil pressure box has no data which exceeds the average value of the pile bottom pressure by 25%, so that the average value of the pile bottom pressure in the time period is the average value of the 4 pressure boxes. And when the pressure is close to 30 h to 35h, the measured value curve measured by the 4 soil pressure boxes fluctuates, the stress of the 4 soil pressure boxes is uneven, and the measured data is corrected to obtain the pile tip pressure value curve, as shown by ✳ -shaped lines in the figure. The pile end pressure can be accurately monitored, the pressure change condition of the pile end holding force layer surface can be accurately reflected, and the whole monitoring of the pile end pressure is realized. The problem of prior art only can bury a soil pressure cell in the pile end, can't reflect the change situation of pile end holding force layer face pressure is solved.

The above embodiments are merely exemplary and are not intended to limit the present invention, and it should be noted that other equivalent variations and modifications made by those skilled in the art in light of the teachings of the present invention should be considered to be within the scope of the present invention.

Claims (10)

1. The utility model provides a modular pile tip pressure monitoring device, includes base, coupling assembling, pressure-bearing subassembly and soil pressure cell, its characterized in that: the base comprises a bottom plate (1) and an enclosure cylindrical barrel (2), a threaded connecting piece I (5) is fixedly connected to the surface of the bottom plate (1), the enclosure cylindrical barrel (2) is tightly sleeved on the periphery of the bottom plate (1), the barrel at the upper part of the enclosure cylindrical barrel is higher than the bottom plate (1) and forms a groove body with the bottom plate (1) in an enclosing mode, fine sand is filled in the groove body, and a plurality of soil pressure boxes (4) are uniformly embedded in the fine sand (3); the connecting assembly comprises a connecting main body (6) arranged above the base, the bottom surface of the connecting main body is in contact with the soil pressure cell (4), the middle of the connecting main body is provided with a central hole channel I (7), the periphery of the central hole channel I (7) is provided with a connecting hole channel I (8) matched with the threaded connecting piece I (5), and the periphery of the connecting main body (6) is fixedly connected with a threaded connecting piece II (9); the pressure-bearing assembly comprises a pressure-bearing main body (10), a central duct II (11) corresponding to the central duct I (7) is arranged on the pressure-bearing main body, and a connecting duct II (12) matched with the threaded connecting piece II (9) is arranged on the periphery of the central duct II (11); the threaded connector I (5) penetrates through the connecting hole channel I (8) to fixedly connect the base with the connecting main body (6), the threaded connector II (9) penetrates through the connecting hole channel II (12) to fixedly connect the connecting main body (6) with the pressure-bearing main body (10), and the upper end of the pressure-bearing main body (10) is fixedly connected with the foundation pile reinforcement cage (13); and the soil pressure box (4) is connected with a signal transmission line (14), and the signal transmission line (14) sequentially penetrates through the central hole channel I (7) and the central hole channel II (11), is upwards bound along the foundation pile reinforcement cage (13), and is connected with the ground data acquisition device.

2. The modular pile tip pressure monitoring device of claim 1, wherein: at least 4 soil pressure cells (4) are embedded and evenly distributed on the same horizontal plane.

3. The modular pile tip pressure monitoring device of claim 1, wherein: the middle part of the connecting main body (6) is of a groove type structure, and a central pore channel I (7) and a connecting pore channel I (8) on the connecting main body are both arranged in the groove.

4. The modular pile tip pressure monitoring device of any of claims 1-3, wherein: the base, the connecting assembly and the pressure-bearing assembly are all made of concrete materials.

5. The modular pile tip pressure monitoring device of any of claims 1-3, wherein: and a wrapping protective sleeve (15) is arranged on the periphery of the connecting main body (6).

6. The modular pile tip pressure monitoring device of any of claims 1-3, wherein: the bottom plate (1), the connecting body (6) and the pressure-bearing body (10) are all internally provided with reinforcing ribs which comprise transverse reinforcing ribs (16) and longitudinal reinforcing ribs (17) which are arranged in a criss-cross mode.

7. The modular pile tip pressure monitoring device of claim 1, wherein: and the outer edge of the bottom plate (1) is provided with an anchor bar (18) for fixing the bottom plate (1) and the enclosure cylindrical barrel (2).

8. The modular pile tip pressure monitoring device of claim 1, wherein: the shapes and the sizes of the base, the connecting assembly and the pressure-bearing assembly are all matched with the pile hole of the foundation pile.

9. The method of assembling a modular pile tip pressure monitoring device of the preceding claim, further comprising: comprises the following steps of (a) carrying out,

step one, burying an earth pressure cell: firstly, uniformly embedding a plurality of soil pressure boxes (4) in fine sand (3) of a base, arranging a connecting assembly above the base, connecting and fixing the connecting assembly and the base through a threaded connecting piece and a nut, and horizontally contacting the bottom surface of the connecting assembly with the soil pressure boxes (4);

step two, calibrating an initial value of the soil pressure cell: the method comprises two steps of coarse adjustment and fine adjustment, wherein the coarse adjustment enables the initial readings of a plurality of soil pressure boxes to be similar by adjusting the flatness of the layer surface of the fine sand (3); then finely adjusting the tightness of the threaded connecting piece and the nut between the base and the connecting component to enable the initial values of the plurality of soil pressure boxes to be equal, and recording the initial reading;

step three, mounting an upper pressure-bearing assembly: the pressure-bearing assembly is arranged above the connecting assembly and is fixedly connected through a threaded connecting piece and a nut, and the upper end of the pressure-bearing assembly is fixedly connected with a foundation pile reinforcement cage (13); and a signal transmission line (14) of the soil pressure box (4) sequentially penetrates through central pore canals of the connecting component and the pressure-bearing component upwards, is bound along the foundation pile reinforcement cage (13) and then is connected with the data acquisition device.

10. The method for testing a combined pile tip pressure monitoring device according to the preceding claim, wherein: comprises the following steps of (a) carrying out,

firstly, pile holes are excavated: excavating a pile hole of the foundation pile according to the embedding depth of the soil pressure box, wherein the bottom of the pile hole is the placement position of the pile end pressure monitoring device;

step two, stably arranging the assembled combined type pile end pressure monitoring device at a preset position at the bottom of a pile hole, pouring concrete into the pile hole to manufacture a foundation pile, and finishing the installation of the combined type pile end pressure monitoring device;

step three, data processing: under the action of pile end pressure, the difference value of the real-time numerical value of each soil pressure box and the initial numerical value of each soil pressure box is a group of pile bottom pressure monitoring data sets, and the average value of each soil pressure box data set is the pile bottom pressure average value; correcting the data, and after eliminating the value which exceeds 25% of the average value of the pile bottom pressure in the measured real-time values, obtaining the corrected data which is the pile end pressure value and is obtained by calculating the average value of the data set again; and drawing the pressure distribution of the pile bottom according to the pressure values of the pile bottom of the soil force box at different embedding depths to obtain the maximum value and the minimum value of the pressure of the pile bottom.

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