CN211172116U - Experimental device for simulating influence of foundation pit excavation on bearing capacity of adjacent building foundation pile - Google Patents

Abstract

The utility model relates to an experimental device for simulating the influence of foundation pit excavation on the bearing capacity of adjacent building foundation piles, comprising a loading frame, a model specimen and a jack. The lower outrigger, the upper outrigger and the lower outrigger extend in the horizontal direction, the model specimen includes the upper wing plate, the lower wing plate and the abdomen, the model specimen is provided with a pile hole, and the pile hole is filled with a grouting body, a jack It includes a vertical jack and a horizontal jack. Both sides of the upper wing plate are supported on the loading column through symmetrically arranged upper legs, and both sides of the lower wing plate are supported on the loading column through symmetrically arranged lower legs respectively. The end of the horizontal jack is provided with an end plate, the belly body is pre-embedded with a screw rod, the screw rod is connected with the end head plate through a tension plate, and displacement gauges are installed symmetrically on both sides of the belly. The device of the utility model can evaluate the adverse effects of foundation pit excavation on the bearing capacity of adjacent building foundation piles, and provide positive reference for foundation pit support schemes and foundation pile reinforcement.

Description

An experimental device for simulating the influence of foundation pit excavation on the bearing capacity of adjacent building foundation piles

technical field

The utility model relates to the field of construction engineering, in particular to an experimental device for simulating the influence of foundation pit excavation on the vertical bearing capacity of adjacent building foundation piles, which is suitable for simulation analysis and quantitative evaluation of sidewall soil mass caused by foundation pit excavation Effects of deformation and stress release on bearing capacity of adjacent building foundation piles.

Background technique

With the development of urban construction, the density of buildings in cities is increasing. With the further development of urbanization, urban high-rise buildings, rail transit, underground projects, subway projects, etc. are still being built vigorously. Therefore, it is inevitable to excavate a large number of deep foundation pit projects. Affected by the urban building density, there are a large number of existing buildings around the foundation pit. The deep foundation pit excavation will inevitably lead to the stress release of the soil on the side wall of the foundation pit, causing the deformation of the foundation pit supporting structure to varying degrees, and finally causing the bottom of the adjacent building, especially the soil around the foundation pile, to the excavation side of the foundation pit to varying degrees. horizontal deformation. The deformation of the soil around the adjacent building piles will cause the soil around the piles to become soft, which in turn causes a decrease in the lateral frictional resistance of the contact surface between the foundation piles and the soil around the piles, which adversely affects the vertical bearing capacity and long-term stability of the building piles. Therefore, it is of great engineering significance to analyze the extent to which the bearing capacity of the adjacent building foundation piles is reduced by the excavation of the foundation pit, and then to evaluate whether the bearing capacity of the building foundation piles still meets the requirements.

However, the testing and evaluation cannot be completed on the project site, and relevant tests are not allowed. Therefore, through the model experiment, quantitative analysis of the impact of foundation pit excavation on adjacent building foundation piles has important reference value for the safety evaluation of the project.

In view of this, the present inventor has conducted in-depth research on the impact of foundation pit excavation on the bearing capacity of adjacent building foundation piles, resulting in this case.

Utility model content

The purpose of the utility model is to provide an experimental device for simulating the influence of foundation pit excavation on the vertical bearing capacity of adjacent building foundation piles, so as to evaluate the adverse effect of foundation pit excavation on the bearing capacity of adjacent building foundation piles, which is the foundation pit Support scheme and foundation pile reinforcement provide a positive reference.

In order to achieve the above purpose, the utility model adopts such technical scheme:

An experimental device for simulating the effect of foundation pit excavation on the bearing capacity of adjacent building foundation piles, including a loading frame, a model specimen and a jack. The loading frame includes a loading beam, a loading column, multiple upper legs and multiple lower legs. The legs and the lower outriggers extend in the horizontal direction. The model specimen includes an upper wing plate, a lower wing plate and a belly body arranged between the upper wing plate and the lower wing plate. There are pile holes in the model specimen, and the pile holes extend from the model The upper end face of the specimen runs through to the lower end face, and the pile hole is filled with grouting body. The jacks include vertical jacks and horizontal jacks. There are multiple horizontal jacks, and multiple horizontal jacks are symmetrically arranged on both sides of the model specimen. Both sides of the plate are supported on the loading column by symmetrically arranged upper legs respectively, both sides of the lower wing plate are supported on the loading column by symmetrically arranged lower legs respectively, and the vertical jack is set on the top of the grouting body. , The end of the horizontal jack is provided with an end plate, the belly body is pre-buried with a screw rod, the screw rod is connected with the end head plate through the tension plate, and displacement gauges are installed symmetrically on both sides of the abdomen.

As a preferred mode of the present invention, the center of the upper wing plate is provided with a circular loading groove, the loading groove extends downward from the upper end surface of the upper wing plate, and a circular loading groove is provided between the loading groove and the vertical jack Steel column, the steel column is arranged in the loading groove, the diameter of the steel column is less than or equal to the diameter of the pile hole, the center of the lower wing plate is provided with a circular bottom groove, and the bottom groove faces from the lower end of the lower wing plate The upper extension, the loading groove, the pile hole and the bottom groove are coaxially arranged.

As a preferred mode of the present invention, the tension plate and the end plate are fixedly connected by tension rods, and the screw rods are locked on the tension plate by nuts.

As a preferred mode of the present invention, there are multiple screw rods located on both sides of the abdominal body, each of the screw rods extends in the horizontal direction, and the plurality of screw rods are in the vertical direction For layout, the vertical spacing between adjacent screw rods located on the same side of the abdominal body is 100-150 mm.

As a preferred mode of the present invention, the number of the loading columns is two, and the two loading columns are respectively arranged at both ends of the loading beam, the loading columns and the loading beam form a gantry, and the loading column The column is fixed in the reaction force groove on the ground through the fixing screw rod. The lower end of the fixing screw rod is provided with a reaction force screw plate, and the reaction force screw plate is located in the reaction force floor groove. The upper end of the screw rod is locked on the fixing plate by the fixing nut, and a reinforcing plate is arranged between the fixing plate and the ground.

As a preferred mode of the present invention, the lower end of the model specimen is provided with a cushion.

As a preferred mode of the present invention, the length of the abdominal body in the horizontal direction is 4-8 times the diameter of the pile hole.

As a preferred mode of the present invention, the upper wing plate and the lower wing plate are symmetrically arranged at the upper and lower ends of the belly body, and the length of the upper wing plate along the horizontal direction is the same as the length of the lower wing plate along the horizontal direction. The length in the horizontal direction is 150-300 mm larger than the length of the abdominal body in the horizontal direction.

As a preferred mode of the present invention, the thickness of the upper wing plate and the thickness of the lower wing plate are both 150-300 mm.

As a preferred mode of the present invention, the diameter of the loading groove is 40-60 mm larger than the diameter of the pile hole.

After adopting the technical scheme of the utility model, it has the following advantages: (1) the vertical jack applies vertical pressure to the grouting body in the model specimen, and the vertical bearing capacity of the grouting body can be measured, and the vertical bearing capacity of the building foundation pile can be simulated. to bearing capacity. (2) By pulling the screw rods through the horizontal jacks on both sides, different horizontal deformations of the abdominal body can be produced on both sides, and different horizontal deformations of the abdominal body can be measured by applying different horizontal pulling forces. (3) For different model specimens, by applying different tensile forces through the horizontal jack, the relationship and variation law between the horizontal deformation of the abdominal body and the vertical bearing capacity of the grouting body can be obtained, simulating the deformation of the sidewall to different degrees caused by the excavation of the foundation pit. The influence and law on the vertical bearing capacity of building foundation piles. (4) Compared with a set of model specimens, the model specimen does not use a horizontal jack to exert tension, and the vertical bearing capacity of the grouting body is measured, which can simulate the vertical bearing capacity of the building foundation pile before the excavation of the foundation pit. (5) By comparing and analyzing the vertical bearing capacity of the grouting body when the horizontal jack does not apply tension and when different horizontal tensions are applied, the vertical bearing capacity of the building foundation piles caused by the horizontal deformation of the sidewall soil caused by the excavation of the foundation pit can be simulated and evaluated Changes and influence laws.

Description of drawings

Fig. 1 is the schematic diagram of the experimental device of the present utility model;

FIG. 2 is a schematic diagram of the cross-sectional structure at the A-A of FIG. 1 of the present utility model.

FIG. 3 is a schematic view of the cross-sectional structure at the B-B position of FIG. 1 of the present utility model.

FIG. 4 is a schematic diagram of the cross-sectional structure at the position C-C of FIG. 1 of the present invention.

FIG. 5 is a schematic diagram of the cross-sectional structure at the point D-D of FIG. 1 of the present invention.

FIG. 6 is a schematic view of the cross-sectional structure at the E-E of FIG. 1 of the present invention.

FIG. 7 is a schematic diagram of the cross-sectional structure at the position F-F of FIG. 1 of the present utility model.

FIG. 8 is a schematic diagram of the cross-sectional structure at G-G of FIG. 1 of the present invention.

FIG. 9 is a schematic diagram of the cross-sectional structure at the H-H of FIG. 1 of the present invention.

FIG. 10 is a schematic diagram of the cross-sectional structure at the J-J position of FIG. 1 of the present invention.

FIG. 11 is a schematic diagram of the cross-sectional structure of the model test piece of the utility model diagram.

FIG. 12 is a schematic diagram of the cross-sectional structure at the position K-K of FIG. 11 of the present invention.

FIG. 13 is a schematic diagram of the cross-sectional structure at L-L of FIG. 11 of the present invention.

FIG. 14 is a schematic diagram of the cross-sectional structure at M-M of FIG. 11 of the present utility model;

Fig. 15 is a schematic cross-sectional structure diagram of the excavation foundation pit and the existing buildings and their foundation piles of the present invention.

Label and Symbol Description

Load beam 11 Load column 12

Reinforcing plate 13 Fixing plate 14

Set Screw Rod 15 Set Nut 16

Reaction screw 17 Upper leg 18

lower leg 19

Vertical Jack 21 Horizontal Jack 22

Steel column 23 Tension plate 24

Tension Rod 25 End Plate 26

Tension hole 27 Connection hole 28

Model Specimen 31 Loading Slots 321

Bottom Slot 322 Upper Wing Plate 331

Lower wing 332 Abdomen 333

Pile hole 34 Grouting body 35

Screw pull rod 36 Nut 37

Displacement meter 38

Pad 4

Ground 51 Reaction Slot 52

Building 61 Pile 62

Support pile 63 Deformed support pile 64

Potential slip zone soil 65 Stable zone soil 66

Potential slip surface 67 Pit bottom 68

pit top 69

Detailed ways

In order to further explain the technical solutions of the present utility model, the following detailed descriptions are given in conjunction with the embodiments.

1 to 15, an experimental device for simulating the influence of foundation pit excavation on the vertical bearing capacity of adjacent building foundation piles includes a loading frame, a jack and a model specimen 31, and the loading frame 1 includes a loading beam 11 , the loading column 12, the upper supporting leg 18 and the lower supporting leg 19, the bottom of the loading column 12 is welded with a reinforcing plate 13 and a fixing plate 14; in the embodiment, the loading column 12 is at least two, two of the The loading columns 12 are respectively arranged at both ends of the loading beam 12 , the loading column 12 and the loading beam 13 form a gantry, and the loading column 13 is fixed in the counter-force groove 52 of the ground 51 through the fixing screw rod 15 The lower end of the fixing screw rod 15 is provided with a reaction force screw plate 17, the reaction force screw plate 17 is located in the reaction force ground groove 52, and the upper end of the fixing screw rod 15 is locked on the fixing plate 14 by the fixing nut 16. In the present invention, the loading frame is not limited to this structure, and other loading frames in the field can also be used.

In the present invention, the jacks include a vertical jack 21 and a horizontal jack 22. There are multiple horizontal jacks 22, which are symmetrically arranged on both sides of the model test piece 31. In the embodiment, the left and right sides of the model test piece 31 Three horizontal jacks 22 are respectively arranged on the sides. The horizontal jacks 22 are installed on the loading column 12 . The ends of the horizontal jacks 22 are provided with end plates 26 .

In the present invention, the model test piece 31 includes an upper wing plate 331, a lower wing plate 332 and a belly 333, and a circular pile hole 34 is provided in the center of the model test piece 31, and the pile hole 34 is filled with a grouting body 35. The center of the upper wing plate 331 is provided with a circular loading groove 321, the center of the lower wing plate 332 is provided with a circular bottom groove 322, the two sides of the abdomen body 333 are symmetrically embedded with screw rods 36, and screw rods 36 By passing through the tension plate 24 and locked on the tension plate 24 by the nut 37, the nut 37 is located between the end plate 26 and the tension plate 24, and the tension rod is passed between the tension plate 24 and the end plate 26 25 are connected together, specifically, the tension plate 24 and the end plate 26 are provided with connection holes 28, and the tension rod 25 passes through the connection hole 28 of the tension plate and the connection hole 28 of the end plate 26 and passes through the The nuts 37 at both ends of the pull rod 25 are used for positioning. A tension hole 27 is provided in the center of the tension plate 24 , and the screw rod 36 passes through the tension hole 27 and is locked by the nut 37 .

In the present invention, the upper wing plate 331 and the lower wing plate 332 are symmetrically supported on the loading column 12 through the upper support leg 18 and the lower support leg 19 respectively, that is, in FIG. The upper legs 18 are symmetrically arranged on the left and right sides of the plate 331, and the lower legs 19 are symmetrically arranged on the left and right sides of the lower wing plate 332. Both the upper legs 18 and the lower legs 19 can be adjusted up and down along the loading column 12 For example, in the art, a plurality of bolt holes are often provided on the loading column 12, and the bolt holes are arranged along the height direction of the loading column 12. By installing the upper leg 18 and the lower leg 19 in different bolt holes, That is, the position adjustment of the upper support leg 18 and the lower support leg 19 can be realized, so that the upper wing plate 331 and the lower wing plate 332 can better abut on the corresponding support legs. The vertical jack 21 is loaded by the steel column 23 placed on the top of the grouting body 35 in the center of the loading groove 321, and the horizontal jack 22 can pull the screw rod 36 through the tension plate 24; the The bottom of the model specimen 31 is provided with a pad 4 which is placed on the ground 51 ; displacement gauges 38 are installed symmetrically on both sides of the abdominal body 333 for detecting the deformation of the abdominal body 333 .

As a preferred solution, the size of the abdominal body 333 (the length of the cross section of the abdominal body 333 along the horizontal direction) is 4-8 times the diameter of the pile hole 34; the upper wing plate 331 and the lower wing plate 332 The length (the length of the cross section of the upper wing plate 331 and the lower wing plate 332 along the horizontal direction) is greater than the size of the belly 333 (the length of the cross section of the belly body 333 along the horizontal direction) by 150-300mm; the upper wing The thickness of the plate 331 and the lower wing plate 332 are both 150-300mm; the diameter of the loading slot 321 and the bottom slot 322 is 40-60mm larger than the diameter of the pile hole; the height of the loading slot 321 and the bottom slot 322 is 40-60mm; the pre-embedded direction of the screw rod 36 is the same as that of the upper wing plate 331, the screw rod 36 located in the abdomen 333 can be pre-installed with nuts 37 at a certain distance, and the screw rod 36 The vertical spacing is 100-150m.

The utility model is an experimental device for simulating the influence of foundation pit excavation on the vertical bearing capacity of adjacent building foundation piles. The construction steps are as follows:

(1) Install the fixed loading frame 1 and the pad 4 according to the design requirements, so that the pad 4 is symmetrically placed on the center line of the loading frame;

(2) Preliminarily install the vertical jack 21 and the horizontal jack 22 according to the size of the model specimen 31;

(3) Hoist the model specimen 31 on the top of the pier 4, and align it, adjust the vertical jack 21 according to the position of the pile hole 34, so that the axis of the vertical jack 21 coincides with the axis of the pile hole 34, and then fix the vertical jack 21 ; Adjust the height of the horizontal jack 22 according to the position of the screw rod 36 embedded on the abdominal body 333, so that the axis of the horizontal jack 22 coincides with the axis of the screw rod 36, and then fix the horizontal jack 22;

(4) Install the tension rod 25 and the tension plate 24 on the end plate 26 of the horizontal jack 22, and then operate the horizontal jack 22 to extend the oil cylinder, so that the tension hole 27 of the tension plate 24 extends into the screw rod 36, Screw the nut 37 from the end of the screw rod 36, and make the nut 37 lightly contact the tension plate 24;

(5) Place the steel column 23 on the top of the grouting body 35 of the loading tank 321, and extend the vertical jack 21 so that the vertical jack 21 slightly contacts the steel column 23;

(6) The displacement gauges 38 are installed symmetrically on both sides of the pre-embedded screw rods 36 in the abdominal body 333;

(7) During the test, when it is necessary to simulate the influence of the horizontal deformation of the supporting structure caused by the excavation of the foundation pit on the bearing capacity of the adjacent building foundation piles, firstly pull all the horizontal jacks 22 synchronously, and pull all the horizontal jacks 22 on the abdominal body 333 of the model specimen 31. The screw pull rod 36 makes the pulling force of the horizontal jack 22 meet the preset requirements; when it is necessary to simulate the bearing capacity of adjacent building foundation piles under normal conditions without foundation pit excavation, do not operate the horizontal jack 22 to pull the screw pull rod 36, or use the The model specimen 31 with the screw rod 36 embedded;

(8) Operate the vertical jack 21 to press the steel column 23, and push the grouting body 35 to move toward the bottom groove 322 until it is destroyed;

(9) Test the average vertical force P ₁ when the grouting body 35 of the model specimen 31 is pushed out to failure when the horizontal jack 22 is not acting; The average vertical force P ₂ when it is pushed out to failure; by comparing P ₁ and P ₂ , the influence of foundation pit excavation on the bearing capacity of adjacent building foundation piles can be evaluated.

Due to the application of the technical scheme, compared with the vertical bearing capacity experiment of traditional building foundation piles, the utility model has the following significant advantages:

(1) Pulling the screw rods 36 through the horizontal jacks 22 on both sides can cause the abdominal body 333 to produce different horizontal deformations to both sides. By applying different horizontal pulling forces, the different horizontal deformations of the abdominal body 333 can be measured, and the foundation pit can be simulated. The horizontal deformation of the supporting structure caused by the excavation causes the deformation of the soil around the adjacent building foundation piles;

(2) The vertical jack 21 exerts vertical pressure on the grouting body 35 in the model specimen 31 through the steel column 23, the vertical bearing capacity of the grouting body 35 can be measured, and the vertical bearing capacity of the building foundation pile under different conditions can be simulated. bearing capacity;

(3) The test does not use the horizontal jack 2 to apply tension to the abdominal body 333 of the model specimen 31 through the screw rod 36, and the vertical bearing capacity P ₁ of the grouting body is measured. The horizontal jack 2 is used to test the model through the screw rod 36. The abdominal body 333 of the piece 31 exerts different tensile forces, and the vertical bearing capacity P ₂ of the grouting body is measured. By comparing P ₁ and P ₂ , the influence of the excavation of the foundation pit on the vertical bearing capacity of the adjacent building piles can be evaluated. .

In order to better understand the impact of foundation pit excavation on existing buildings, Figure 15 shows the schematic cross-sectional structure of foundation pit excavation and existing buildings and their foundation piles, which shows building 61, located below the building The foundation piles 62, the supporting piles 63, the deformed supporting piles 64 (shown with dotted lines in the figure), the soil mass in the potential slip zone 65, the soil mass in the stable zone 66, the potential slippage surface 67, the pit bottom 68, the pit The specific position of the top 69 and the relative positional relationship between them.

The present utility model has been described in detail above in conjunction with the accompanying drawings, but the embodiments of the present utility model are not limited to the above-mentioned embodiments. Those skilled in the art can make various modifications to the present utility model according to the prior art, which all belong to the present utility model. scope of protection.

Claims (10)

1. the experimental device that simulates the impact of foundation pit excavation on the bearing capacity of adjacent building foundation piles, it is characterized in that: comprising a loading frame, a model specimen and a jack, the loading frame comprises a loading beam, a loading column, a plurality of upper legs and a plurality of The lower outrigger, the upper outrigger and the lower outrigger extend in the horizontal direction, the model specimen includes an upper wing plate, a lower wing plate and a belly body arranged between the upper wing plate and the lower wing plate, and the model specimen is provided with a pile The hole, the pile hole runs from the upper end face of the model specimen to the lower end face, the pile hole is filled with grouting body, the jacks include vertical jacks and horizontal jacks, there are multiple horizontal jacks, and multiple horizontal jacks are symmetrically arranged on the model specimen. The two sides of the upper wing plate are supported on the loading column by the symmetrically arranged upper legs respectively, and the two sides of the lower wing plate are respectively supported on the loading column by the symmetrically arranged lower legs, and the vertical jacks correspond to The top of the grouting body is arranged, the end of the horizontal jack is provided with an end plate, and the belly is embedded with a screw rod, which is connected to the end head plate through a tension plate, and displacement gauges are installed symmetrically on both sides of the abdomen. 2. The experimental device for simulating the influence of foundation pit excavation on the bearing capacity of adjacent building foundation piles as claimed in claim 1, characterized in that: the center of the upper wing plate is provided with a circular loading groove, and the loading groove extends from the upper The upper end of the wing plate extends downward, a steel column is arranged between the loading groove and the vertical jack, the steel column is arranged in the loading groove, the diameter of the steel column is less than or equal to the diameter of the pile hole, and the lower wing plate The center is provided with a circular bottom groove, the bottom groove extends upward from the lower end face of the lower wing plate, and the loading groove, the pile hole and the bottom groove are coaxially arranged. 3. The experimental device for simulating the influence of foundation pit excavation on the bearing capacity of adjacent building foundation piles as claimed in claim 1, wherein the tension plate and the end plate are fixedly connected by tension rods, and the screws The pull rod is locked on the tension plate by a nut. 4. the experimental device that simulates the impact of foundation pit excavation on the bearing capacity of adjacent building foundation piles as claimed in claim 1, it is characterized in that: the described screw tie rods located on both sides of described abdomen are multiple, each The screw pull rods all extend in the horizontal direction, a plurality of the screw pull rods are arranged in the vertical direction, and the vertical distance between the adjacent screw pull rods on the same side of the abdomen is 100-150 mm. 5. The experimental device for simulating the influence of foundation pit excavation on the bearing capacity of adjacent building foundation piles as claimed in claim 1, wherein the number of the loading columns is two, and the two loading columns are respectively arranged on the loading beams The two ends of the loading column and the loading beam form a gantry. The loading column is fixed in the reaction force groove on the ground by a fixing screw rod. The lower end of the fixing screw rod is provided with a reaction force screw plate, and the reaction force screw The plate is located in the reaction force ground groove, a fixing plate is arranged on the loading column, the upper end of the fixing screw rod is locked on the fixing plate by a fixing nut, and a reinforcing plate is arranged between the fixing plate and the ground. 6 . The experimental device for simulating the effect of foundation pit excavation on the bearing capacity of adjacent building foundation piles according to claim 1 , wherein the lower end of the model specimen is provided with a pier. 7 . 7. The experimental device for simulating the influence of foundation pit excavation on the bearing capacity of adjacent building foundation piles as claimed in claim 1, wherein the length of the abdominal body in the horizontal direction is 4-8 times the diameter of the hole diameter of the pile hole. times. 8. The experimental device for simulating the influence of foundation pit excavation on the bearing capacity of adjacent building foundation piles as claimed in claim 1, wherein the upper wing plate and the lower wing plate are symmetrically arranged on the upper and lower sides of the abdominal body. At both ends, the length of the upper wing plate along the horizontal direction and the length of the lower wing plate along the horizontal direction are both 150-300 mm larger than the length of the belly body along the horizontal direction. 9. The experimental device for simulating the influence of foundation pit excavation on the bearing capacity of adjacent building foundation piles as claimed in claim 1, wherein the thickness of the upper wing plate and the thickness of the lower wing plate are both 150-300mm . 10 . The experimental device for simulating the effect of foundation pit excavation on the bearing capacity of adjacent building foundation piles according to claim 2 , wherein the diameter of the loading groove is larger than the diameter of the pile hole by 40-60 mm. 11 .

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