CN116539434A - Ground traffic load simulation test method above prefabricated box culvert - Google Patents

Abstract

The invention discloses a ground traffic load simulation test method above a prefabricated box culvert, comprising: placing a model box on the base of a reaction force steel frame; Calculate and adjust the amount of expansion and contraction; carry out vertical loading; push the model sleeve on the model slide rail to enter the inside of the model box from the round hole on the steel plate in front of the model box, excavate the soil pouring into the tunnel, and close the model Put the steel plate on the box; extend the monitoring device into the square tunnel model; install the horizontal jack for axial loading; fill the box with water through the water pipe at the bottom of the model box to the required water injection volume, and continue to adjust the loading of the above jacks to the required level; through the preset sensor Collect corresponding data, measure the deformation and convergence deformation of the square tunnel model under random external loads, and the pressure of the surrounding soil on the square tunnel model; this invention solves the problem that the existing test devices and methods cannot meet the needs of actual working conditions question.

Description

A simulation test method for ground traffic loads above prefabricated box culverts

technical field

The invention belongs to the field of subway engineering, and in particular relates to a ground traffic load simulation test method above a prefabricated box culvert.

Background technique

In recent years, the underground transportation system in large and medium-sized cities has been continuously improved and the number of tunnels has continued to increase. After the tunnels are put into operation, due to the effect of traffic loads, the long-term stress and strain effects on ground settlement, surrounding buildings, and underground pipelines cannot be ignored. In order to avoid the long-term driving load on the surface causing deformation and excessive stress on the operating tunnel below, which endangers the safety of the tunnel operation, the upper span foundation pit is often excavated in partitions and blocks, and it is combined with soil or counterweight back pressure. In order to simulate and analyze the impact of the long-term driving load on the upper part of the box culvert tunnel on the existing operating shield tunnel below, several sets of model test devices were designed and developed to carry out model test analysis on this working condition. And in the case of excessive force, for the direction of the compressive load test in different areas, the model test devices currently developed have some defects that the rock and soil materials in the device cannot be loaded in different areas, and cannot be unloaded in stages; in addition, each device must Putting the tunnel first, and then applying load to consolidate the soil is inconsistent with the actual construction sequence; the deformation convergence monitoring of the square tunnel model is not perfect.

Contents of the invention

The object of the present invention is to propose a ground traffic load simulation test method above a prefabricated box culvert in order to solve the problem that the existing test devices and methods cannot meet the requirements of actual working conditions.

In order to achieve the above object, the present invention adopts the following technical solutions:

A ground traffic load simulation test method above a prefabricated box culvert, comprising:

S1: Place the model box on the base of the reaction force steel frame, and then fix the openable steel plate on the front of the model box to the model box with bolts;

S2: Place the water injection pipe at the bottom of the model box, then flatten the coarse sand until the water injection pipe is completely buried, cover the upper part of the coarse sand with permeable stone, add soil to the predetermined height in the model box according to the test plan, and then lower the lifting device to lowest position;

S3: Calculating and adjusting the telescopic amount of the telescopic rod of the deformable pressure-bearing device;

S4: Perform vertical loading: use the reaction frame, cross-shaped slide rail, small vertical jack, and deformable pressure-bearing device to accurately apply pressure to the soil in the model box and reach the expected level, and the soil in the model box is compressed;

S5. Push the model sleeve on the model slide rail to enter the model box from the round hole on the steel plate in front of the model box, and manually excavate the soil pouring into the tunnel, put the square tunnel model completely, and then close the model box Upper steel plate;

S6. Extend the monitoring device into the inside of the square tunnel model;

S7. Install a horizontal jack and carry out axial loading through the horizontal jack;

S8. Fill the tank with water through the water pipe at the bottom of the model tank to the required water injection volume, and continue to adjust the loading of the above-mentioned jacks to the required level;

S9. After the model is compressed, internal forces and deformations are generated, and the corresponding data is collected through preset sensors to measure the deformation and convergence deformation of the square tunnel model under random external loads, as well as the pressure of the surrounding soil on the square tunnel model.

As a further description of the above technical solution:

The method for calculating the expansion and contraction of the telescopic rod of the deformable pressure bearing device in S3 includes:

s1: Add the soil completely into the model box and make it reach the predetermined compaction degree;

s2: measure the relationship between soil height H, soil density ρ, soil particle specific gravity d _s , soil water content ω, soil void ratio e and vertical compressive stress p under confinement conditions in the model box;

s3: Calculate the weight γ of each group of soil according to the formula γ=ρg, and draw the relationship curve between the void ratio e and the vertical compressive stress p of each group of soil in the confined compression test, according to the formula Calculate the compression coefficient a of each group of soil;

s4: Mesh the soil at the horizontal plane where the axis of the square tunnel model is located during the test, and pre-set the total soil stress σ _j at the intersection of each vertical and horizontal line, and the value of σ _j is equal to that in the actual working condition;

s5 calculates the soil in the model box, calculates the self-weight stress σ _zj of the soil at this place, calculates the additional stress p _j of the soil at this place, and finally calculates the settlement value s _j of the soil at this place;

s6: The settlement value s _j of each soil mass obtained based on s5, that is, the deformation value of the corresponding rotating steel plate above the soil; measure the pitch P of the telescopic rod around the deformable pressure-bearing device, and calculate the rotation circle of the telescopic rod at this position according to the formula number

s7: Based on the number of rotations of each telescopic rod obtained in s6 Adjust all telescopic rods, and then test according to the test requirements.

As a further description of the above technical solution:

The opening of the model box is placed in the reaction steel frame, and the reaction steel frame is composed of a base and vertically fixed rods at the four corners of the base; there is a square tunnel model placed front and back in the model box , the square tunnel model is equipped with a monitoring device inside; the bottom of the box is equipped with a water injection pipe; the front of the box is equipped with a model slide rail, and there is a model sleeve along the front and rear direction on the model slide rail; The lifting device is equipped with an integral loading device vertically. There are multiple split loading devices distributed in a rectangular array under the integral loading device. The split loading devices are placed above the soil layer; the lifting device drives the integral loading device to move up and down. , increase and decrease the load on multiple split loading devices, simulate the partitioned loading and stage unloading of the soil layer, and monitor the pressure changes generated by the square tunnel model in the soil layer through the monitoring device.

As a further description of the above technical solution:

The front side of the model box is composed of plexiglass plates on the left and right sides and a middle steel plate, the upper and lower ends of the middle steel plate are fixed on the model box, and there is a round hole in the middle of the middle steel plate, through which the square tunnel model Placed in the model box; the front side of the middle steel plate is hinged with a door panel, and the four corners of the door panel are bolted to the model box to close the round hole.

As a further description of the above technical solution:

The square tunnel model is a cylinder composed of a plurality of arc-shaped tunnel segments, a horizontal steel plate is fixed at the upper and lower ends of the rear side of the box, a vertical steel plate is fixed between the two horizontal steel plates, and the front of the vertical steel plate is A horizontal jack 8 is fixed in the middle of the side, and the front end of the horizontal jack is fixed on the square tunnel model.

As a further description of the above technical solution:

The front side of the model box is provided with an L-shaped bracket, a cross bar is arranged between the L-shaped bracket and the vertical steel plate, the cross bar is placed in the square tunnel model and is coaxial with the square tunnel model; the upper circumference of the cross bar There are multiple laser rangefinders evenly distributed in the front and rear arrays, and the L-shaped bracket, crossbar, and laser rangefinders together form a monitoring device.

As a further description of the above technical solution:

The model sleeve is composed of a plurality of curved plates evenly distributed around the circumference, and the adjacent curved plates are engaged by groove-and-groove seams. The length of the model sleeve is 1.1 times that of the square tunnel model, and the internal diameter of the model sleeve is the same as that of the square tunnel model. The outer diameters are the same; the model slide rail is a steel frame shaped like an inverted fish abdomen, and the model sleeve is placed in the model slide rail.

As a further description of the above technical solution:

The lifting device is composed of a hollow lifting sleeve set on the frame rod and a horizontal beam slide rail connecting each hollow lifting sleeve; the position above the height of the model box on the frame rod is provided with sawtooth, and the upper end surface of each sawtooth is flat. The lower end surface is an upwardly inclined slope; there are multiple bolt holes distributed vertically and equidistantly on the sawtooth frame rod; a rotating rod is hinged on the side of the sawtooth inside the hollow lifting sleeve, and the rotating rod can see all the sawtooth. One end is hinged with a pressing rod, the lower end of the pressing rod is placed between the saw teeth, and a spring is connected between the upper end of the pressing rod and the rotating rod.

As a further description of the above technical solution:

The overall loading device includes a cross-shaped slide rail, a large vertical jack and a loading plate; There is a loading plate under the vertical jack, and the loading plate is composed of two upper and lower backing plates and a plurality of I-beams between the two backing plates; the cross-shaped slide rail is composed of a hollowed out round table and two mutual It is composed of vertical T-shaped bars, and a C-shaped member is fixed at both ends of the T-shaped bar. The C-shaped member is fixed and connected to the horizontal beam slide rail on the corresponding side by bolts; the upper end of the large vertical jack is fixed under the hollowed-out round platform.

As a further description of the above technical solution:

The split loading device includes a small vertical jack, a deformable pressure-bearing device and a partition plate; a plurality of small vertical jacks are distributed in a rectangular array on the lower end of the loading plate, and there is a deformable vertical jack under each small vertical jack. Pressure-bearing device; each deformable pressure-bearing device has a box-shaped partition plate, the partition plate wraps the corresponding small vertical jack, and the adjacent partition plates are connected by bolts The deformable pressure-bearing device includes an upper rectangular steel plate, and there is a lower rectangular steel plate directly below the upper rectangular steel plate. A triangular rotating steel plate is hinged on the four sides of each rotating steel plate. When the rotating steel plate is rotated to a horizontal position, the lower rectangular steel plate and the four rotating steel plates together form a steel plate as large as the upper rectangular steel plate; A telescopic rod is connected through a ball hinge, and the upper ends of the telescopic rod are all fixed on the upper rectangular steel plate, and the upper steel plate, the telescopic rod, the lower steel plate and the rotating steel plate together form a deformable pressure bearing device. The outer edge surface of the telescopic rod of the deformable pressure bearing device and the inner edge surface of one end of the ball hinge are screw threaded.

In summary, owing to adopting above-mentioned technical scheme, the beneficial effect of the present invention is:

(1) The deformable pressure-bearing device in the present invention can be coupled and linked with the upper jack to accurately apply continuously changing pressure to the lower soil, which can realize the continuous loading process of the lower soil and more truly reflect the stress state of the actual engineering on site.

(2) The present invention can express the stress constraint form that cannot be directly observed in the test process as the displacement constraint form that can be directly observed, so that the soil in the model box can be more intuitively and conveniently analyzed at the initial stage of loading impose constraints.

(3) The deformable pressure-bearing backing plate in the present invention can be coupled and linked with the upper small vertical jack to accurately apply continuously changing pressure to the lower soil, which can realize the continuous loading process of the lower soil and more truly reflect the actual engineering on site State of stress.

(4) The device of the present invention can not only simulate the working conditions of synchronous excavation or backpressure in any area or multiple areas above the square tunnel model, and the loading and unloading of each area can be adjusted arbitrarily, and it can also fill the box with soil first, and then add After unloading, the square tunnel model is pushed horizontally into the soil, which not only accurately simulates the initial stress field of the formation, but also makes the confining pressure effect of the surrounding soil on the square tunnel model closer to reality. Compared with the existing simulation, it can more accurately simulate and analyze the impact of the additional loading and unloading effects of various forms of foundation pit excavation on the top of the shield tunnel in operation or the impact of loading and unloading on the deformation and internal force of the existing operating tunnel. Rich.

Description of drawings

Fig. 1 is the three-dimensional structure schematic diagram of the present invention;

Fig. 2 is the internal three-dimensional structure schematic diagram after removing model box 3 and dividing plate 19 of the present invention;

Fig. 3 is a three-dimensional structural schematic diagram of an integral loading device and a split loading device;

FIG. 4 is a three-dimensional structural schematic diagram of the deformable pressure-bearing device 18;

Fig. 5 is a three-dimensional structural schematic diagram of the reaction force steel frame and the lifting device 11;

Fig. 6 is a schematic cutaway view of the interior of the lifting device 11;

FIG. 7 is a schematic perspective view of the three-dimensional structure of the model slide rail 9 .

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

Please refer to Fig. 1-7, the present invention provides a kind of ground traffic load simulation test method above the prefabricated box culvert:

A ground traffic load simulation test method above a prefabricated box culvert, comprising:

S1: Place the model box 3 on the base of the reaction steel frame 1, and then fix the openable steel plate on the front of the model box 3 to the model box 3 by bolts;

S2: Place the water injection pipe 5 at the bottom of the model box 3, then spread coarse sand until the water injection pipe 5 is completely buried, cover the upper part of the coarse sand with permeable stones, add soil to the model box 3 to a predetermined height according to the test plan, and then place the Lifting device 11 is lowered to the lowest position;

S3: Calculating and adjusting the telescopic amount of the telescopic rod 23 of the deformable pressure-bearing device 18;

S4: Perform vertical loading: use the reaction frame, cross-shaped slide rail, small vertical jack 17, and deformable pressure-bearing device 18 to accurately apply pressure to the soil in the model box 3 and reach the expected level. The soil in the model box 3 compressed;

S5. Push the model sleeve 10 on the model slide rail 9 to enter the inside of the model box 3 from the round hole on the steel plate in front of the model box 3, manually excavate the soil pouring into the tunnel, and put the square tunnel model 4 completely Close the model box 3 upper steel plate afterward;

S6. Extend the monitoring device into the inside of the square tunnel model 4;

S7. install horizontal jack 8, and carry out axial loading by horizontal jack 8;

S8. Fill the tank with water through the water pipe at the bottom of the model tank to the required water injection volume, and continue to adjust the loading of the above-mentioned jacks to the required level;

S9. After the model is compressed, the internal force and deformation are generated, and the corresponding data is collected through the preset sensor to measure the deformation and convergence deformation of the square tunnel model 4 under random external loads, as well as the pressure of the surrounding soil on the square tunnel model 4 .

The method for calculating the expansion and contraction of the telescopic rod 23 of the deformable pressure bearing device 18 in the described S3 includes:

s1: Completely add the soil body into the model box 3, and make it reach the predetermined compaction degree;

s2: Measure the relationship between soil height H, soil density ρ, soil particle specific gravity d _s , soil water content ω, soil void ratio e and vertical compressive stress p under confinement conditions in the model box 3;

s3: Calculate the weight γ of each group of soil according to the formula γ=ρg, and draw the relationship curve between the void ratio e and the vertical compressive stress p of each group of soil in the confined compression test, according to the formula Calculate the compression coefficient a of each group of soil;

s4: Mesh the soil on the horizontal plane where the 4-axis of the square tunnel model is located during the test, and pre-set the total stress σ _j of the soil at the intersection of each vertical and horizontal line. The value of σ _j is equal to that in the actual working condition ;

s5 calculates the soil in the model box 3, calculates the self-weight stress σ _zj of the soil at this place, calculates the additional stress p _j of the soil at this place, and finally calculates the settlement value s _j of the soil at this place;

s6: the settlement value s _j of each soil mass obtained based on s5, that is, the deformation value of the corresponding rotating steel plate 22 above the soil mass; measure the pitch P of the telescopic rod 23 around the deformable pressure-bearing device 18, and calculate the expansion and contraction of the position according to the formula Number of turns of rod 23

s7: based on the number of rotations of each telescopic rod 23 obtained in s6 All telescopic rods 23 are adjusted, and then tested according to the test requirements.

The opening of the model box 3 is placed upwards in the reaction force steel frame, and the reaction force steel frame is composed of the base 1 and the frame rods 2 vertically fixed at the four corners of the base 1 respectively; Placed square tunnel model 4, the inside of the square tunnel model 4 is equipped with a monitoring device; the bottom of the box is provided with a water injection pipe 5; the front side of the box is provided with a model slide rail 9, and there is a model sleeve along the front and rear Tube 10; the frame bar 2 is provided with a lifting device 11 that can move up and down, and an integral loading device is vertically provided on the lifting device 11, and a plurality of split loading devices are distributed in a rectangular array below the integral loading device. above the soil layer; the lifting device 11 drives the overall loading device to move up and down, and increases or decreases the load on multiple split loading devices, simulating the partitioned loading and staged unloading of the soil layer, and the monitoring device monitors the square tunnel in the soil layer. The pressure changes produced by Model 4 were monitored.

The front side of described model case 3 is made up of the plexiglass plate 24 of left and right sides and middle steel plate 25, and the upper and lower ends of middle steel plate 25 are all fixed on the model case 3, and there is a round hole in the middle of middle steel plate 25, through The square tunnel model 4 is placed in the model box 3 in the round hole; a door panel 26 is hinged on the front side of the middle steel plate 25, and the four corners of the door panel 26 are all fastened by bolts to make the door panel 26 close to the model box 3. The hole is closed.

The square tunnel model 4 is a cylinder composed of a plurality of arc-shaped tunnel segments, a horizontal steel plate 6 is fixed at the upper and lower ends of the rear side of the box, and a vertical steel plate 7 is fixed between the two horizontal steel plates 6, A horizontal jack 8 is fixed in the middle of the front side of the vertical steel plate 7, and the front end of the horizontal jack 8 is fixed on the square tunnel model 4.

The front side of described model case 3 is provided with an L-shaped support 27, and a cross bar 28 is arranged between the L-shaped support 27 and the vertical steel plate 7, and cross bar 28 is placed in the square tunnel model 4 and is connected with the square tunnel model 4. Concentric; the upper circumference of the cross bar 28 is evenly distributed and a plurality of laser range finders 29 are distributed in front and rear arrays. The L-shaped bracket 27, the cross bar 28 and the laser range finder 29 together form a monitoring device.

The model sleeve 10 is composed of a plurality of curved plates 30 evenly distributed on the circumference, and the adjacent curved plates 30 are engaged by a tongue-and-groove seam. The length of the model sleeve 10 is 1.1 times that of the square tunnel model 4. The model sleeve 10 The inner diameter is the same as the outer diameter of the square tunnel model 4; the model slide rail 9 is a steel frame shaped like an upside-down fish belly, and the model sleeve 10 is placed in the model slide rail 9.

The lifting device 11 is composed of a hollow lifting sleeve 36 set on the pole 2 and a horizontal beam slide rail 37 connecting each hollow lifting sleeve 36; the position above the height of the model box 3 on the pole 2 is provided with sawtooth 38 , the upper end face of each sawtooth 38 is flush, and the lower end face is an upwardly inclined slope; there are a plurality of bolt holes 39 that are vertically equidistantly distributed on the frame bar 2 with sawtooth 38; One side is hinged with a rotating rod 40, and one end of the rotating rod 40 seeing the sawtooth 38 is hinged with a depression rod 41, the lower end of the depression rod 41 is placed between the saw teeth 38, and a spring is connected between the depression rod 41 upper end and the rotation rod 40 42.

The overall loading device comprises a cross-shaped slide rail, a large vertical jack 14 and a loading plate; 14. There is a loading plate under the large vertical jack 14. The loading plate is composed of two upper and lower backing plates 15 and a plurality of I-beams 16 between the two backing plates 15; It is composed of two mutually perpendicular T-shaped bars 44 inserted thereon, and a C-shaped member 45 is fixed at both ends of the T-shaped bar 44, and the C-shaped member 45 is fixedly connected to the horizontal beam slide rail 37 on the corresponding side by bolts; The upper end of the large vertical jack 14 is fixed below the hollowed-out round platform 43 .

The split loading device includes a small vertical jack 17, a deformable pressure bearing device 18 and a partition plate 19; a plurality of small vertical jacks 17 are distributed in a rectangular array on the lower end of the loading plate, and each small vertical jack 17 below There is a deformable pressure-bearing device 18; each deformable pressure-bearing device 18 has a square-shaped partition plate 19, and the partition plate 19 wraps the corresponding small vertical jack 17, and the adjacent The partition plates 19 are fastened and connected by bolts; the deformable pressure bearing device 18 includes an upper rectangular steel plate 20, and there is a lower rectangular steel plate 21 directly below the upper rectangular steel plate 20. In the vertical direction, the lower rectangular steel plate 21 The apexes of the upper rectangular steel plate 20 are respectively placed in the middle of the side lengths of the upper rectangular steel plate 21, and a triangular rotating steel plate 22 is hinged on the four sides of the lower rectangular steel plate 21. When the rotating steel plate 22 rotates to a horizontal position, the lower rectangular steel plate 21 and the four rotating steel plates 22 together form a steel plate as large as the upper rectangular steel plate 20; the upper end surface of each rotating steel plate 22 is connected with a telescopic rod 23 by a ball hinge, and the upper end of the telescopic rod 23 is fixed on the upper rectangular steel plate 20, and the upper steel plate , telescopic rod 23, lower steel plate and rotating steel plate 22 form deformable pressure-bearing device 18 together. The outer edge surface of the telescopic rod 23 of the deformable pressure bearing device 18 is threadedly fitted with the inner edge surface of one end of the ball hinge.

working principle:

In this device, the lifting device 11 can be freely lifted and lowered along the sawtooth 38, thereby changing the height of the lifting device 11, and the bolt holes 39 can be used to fix the lifting device 11. The vertical partition plates 19 are distributed in vertical and horizontal arrays, and are connected with each other by bolts, which are used to partition the soil in the box and prevent the deformable pressure-bearing device 18 from tilting. During the test, the monitoring device is inserted into the square tunnel model 4 to measure the compression and tensile deformation of the square tunnel model 4, that is, the convergence deformation. The miniature earth pressure sensor is installed at the bottom of the deformable pressure-bearing device 18, and can monitor the pressure of the deformable pressure-bearing device 18.

The entire square tunnel model 4 is based on similarity theory calculations, using plexiglass, and splicing through custom-made pure aluminum welding wire bolts. During the test, the miniature earth pressure sensor was pasted on the outer arc surface of the square tunnel model 4 to measure the earth pressure acting on the square tunnel model 4. During the test, the strain gauge is pasted on the inner arc surface of the square tunnel model 4, so that the deformation of the square tunnel model 4 can be monitored.

After adding rock and soil materials to the model box 3 and applying a load, the model sleeve 10 can be inserted into the rock and soil body at the position of the reserved round hole in the model box 3, and then the soil in the model sleeve 10 is excavated and put into a square tunnel Model 4, and then the model sleeve 10 is taken out in pieces, which plays the role of assisting the square tunnel model 4 to be put into the model box 3.

When in use, the model box 3 is first placed on the counter force steel frame base 1, and then the openable steel plate on the front of the model box 3 is fixed on the model box 3 by bolts.

Place the water injection pipe 5 at the bottom of the model box 3, then flatten the coarse sand to completely bury the water injection pipe 5, cover the upper part of the coarse sand with permeable stone, add soil to the predetermined height in the model box 3 according to the test plan, and then move the lifting device 11 Lower to lowest position.

Calculating and adjusting the expansion and contraction of the telescopic rod 23 of the deformable pressure bearing device 18, including:

s1: Completely add the soil body into the model box 3, and make it reach the predetermined compaction degree;

s2: Measure the height H of the soil in the model box 3. For the area where the soil in the box is vertically layered, measure the height H _i of each layer of soil; at this time, according to the distribution of soil types in the model box 3, select several groups appropriately Conduct soil density test, soil particle specific gravity test, soil water content test, and indoor confining compression test on the undisturbed soil in different areas; after taking soil, add soil of the same state to the original soil taking place; record the geotechnical test mentioned in S1 The results: the relationship between soil density ρ, soil particle specific gravity d _s , soil water content ω, soil void ratio e and vertical compressive stress p under confinement conditions;

s3: Calculate the weight γ of each group of soil according to the formula γ=ρg, and draw the relationship curve between the void ratio e and the vertical compressive stress p of each group of soil in the confined compression test, according to the formula Calculate the compression coefficient a of each group of soil in S1;

s4: Mesh the soil on the horizontal plane where the 4-axis of the square tunnel model is located during the test, and pre-set the total stress σ _j of the soil at the intersection of each vertical and horizontal line. The value of σ _j is equal to that in the actual working condition ,details as follows:

Use the pseudo-static method to simplify the vehicle load to static load: F＝k ₁ k ₂ P ₀ ;

Dynamic stress of subgrade surface

Calculate the self-weight stress of the soil in the actual working condition

Calculate the total soil stress σ _j = σ _a + σ _za ;

Among them, k ₁ is the stacking coefficient, k ₂ is the dispersion coefficient, P ₀ is the wheel static load, A is the area per unit length of the subgrade surface, γ _a represents the weight of each layer of soil, and H _a represents the corresponding soil height;

s5 calculates the soil in the model box, calculates the self-weight stress σ _zj of the soil at this place, calculates the additional stress p _j of the soil at this place, and finally calculates the settlement value s _j of the soil at this place, as follows:

Calculation formula of self-weight stress σ _zj of soil:

The formula for calculating the additional stress p _j of the soil: p _j = σ-σ _z ;

Calculation formula of soil settlement value s _j :

Among them, γ _i represents the weight of each layer of soil, and H _i represents the corresponding soil height;

s6: the settlement value s _j of each soil mass obtained based on s5, that is, the deformation value of the corresponding rotating steel plate 22 above the soil mass; measure the pitch P of the telescopic rod 23 around the deformable pressure-bearing device 18, and calculate the expansion and contraction of the position according to the formula Number of turns of rod 23

s7: based on the number of rotations of each telescopic rod 23 obtained in s6 All telescopic rods 23 are adjusted.

A vertical partition 19 is installed on the top of the soil body in the model box 3 , and the deformable pressure-bearing device 18 is placed inside the vertical partition 19 . Place a small vertical jack 17 on the top of the deformable pressure bearing device 18, and then place a backing plate 15 above the jack. A plurality of I-beams 16 are placed on the backing plate 15, and a backing plate 15 is placed above the I-beam 16 to form a loading plate. Then the hollowed-out round table 43 is assembled with the cross-shaped slide rail, and four specific buckles are clamped on the four sides of the lifting device 11, and each end of the cross-shaped slide rail is connected with the buckle by bolts. Hang the large vertical jack 14 under the hollowed-out round table 43, adjust the height of the lifting device 11, slide the cross-shaped slide rail to adjust the large vertical jack 14 to an appropriate position, carry out vertical loading, and then adjust the deformation degree of the deformable pressure-bearing device 18 , and then use small vertical jacks 17 to load.

After the above steps are completed and the applied pressure reaches the expected level, unscrew the front bolt of the model box 3 to open the window, and remove the circular steel plate outside the window, and place the model slide rail 9 vertically on the model box 3 Front side, and make the center of the model slide rail 9 coincide with the center of the model box 3 window. Apply active carbon to the outer surface of the model sleeve 10, and then completely wrap the sleeve with a polyethylene film, then put the model sleeve 10 into pieces and put them into the model slide rail 9 from one end in stages, insert the model sleeve 10 into the soil, Until it is against the other side of the model box 3. The soil in the model sleeve 10 is manually excavated, and then the assembled square tunnel model 4 is put into the model sleeve 10 . The model sleeve 10 is extracted by the piece, and then the front window of the model box 3 is tightly closed by bolts, and the small window obtained by removing the circular steel plate is stretched into the monitoring device. Connect the reaction frame to the back plate of the model box 3 through bolts on the back of the model box 3, install the horizontal jack 8, and use the horizontal jack 8 to load the axial force, and fill the box with water to the required amount through the water pipe at the bottom of the model box 3 . Continue to adjust the loading of the above-mentioned jacks to the required level.

In the present invention, by calculating the amount of expansion and contraction of the telescopic rod 23 of the deformable pressure-bearing device 18, the expected stress constraint is converted into a displacement constraint. With the different displacement constraints imposed by the deformable pressure-bearing devices 18 above the fill, the model box 3 The inner soil is compressed, and then generates pressure on the square tunnel model 4, and the model generates internal force and deformation after being compressed. By collecting corresponding data through preset sensors, the deformation and convergent deformation of the square tunnel model 4 under random external loads, and the pressure of the surrounding soil on the square tunnel model 4 can be measured. The degree of deformation of the square tunnel model 4 is collected by the foil strain gauge attached to the inside of the square tunnel model 4 and the displacement sensor extending into the inside of the square tunnel model 4 .

The shield tunnel in the present invention is subject to non-uniform distribution force integrated loading model test device can complete the following test: under the action of vertical jack loading, the square tunnel model 4 is subjected to three-dimensional loading pressure, resulting in deformation, can analyze the tunnel in non-uniform distribution Deformation law under load; first use the vertical jack to load to the required level to cause a certain deformation of the tunnel, and then reduce the pressure of the jack to unload the soil around the tunnel to simulate the excavation of the foundation pit in the actual project. To study the influence of foundation pit excavation on the force and deformation of the underlying tunnel.

The above is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art within the technical scope disclosed in the present invention, according to the technical solutions of the present invention and its Any equivalent replacement or change of the inventive concept shall fall within the protection scope of the present invention.

Claims (10)

1. A ground traffic load simulation test method above a prefabricated box culvert, characterized in that, S1: Place the model box (3) on the reaction force steel frame base (1), and then fix the openable steel plate on the front of the model box (3) to the model box (3) by bolts; S2: Place the water injection pipe (5) at the bottom of the model box (3), then spread coarse sand until the water injection pipe (5) is completely buried, cover the upper part of the coarse sand with permeable stone, and add water to the model box (3) according to the test plan After the soil reaches a predetermined height, the lifting device (11) is lowered to the lowest position; S3: Calculating and adjusting the telescopic amount of the telescopic rod (23) of the deformable pressure-bearing device (18); S4: Perform vertical loading: use the reaction frame, cross-shaped slide rail, small vertical jack (17), and deformable pressure-bearing device (18) to accurately apply pressure to the soil in the model box (3) and reach the expected level, The soil in the model box (3) is compressed; S5: Push the model sleeve (10) on the model slide rail (9) to enter the inside of the model box (3) from the round hole on the steel plate in front of the model box (3), and manually excavate the soil poured into the tunnel, Put the square tunnel model (4) into the back and tightly close the upper steel plate of the model box (3); S6: extending the monitoring device into the inside of the square tunnel model (4); S7: installing a horizontal jack (8), and carrying out axial loading through the horizontal jack (8); S8: Inject water into the box through the water pipe at the bottom of the model box to the required water injection volume, and continue to adjust the loading of the above-mentioned jacks to the required level; S9: After the model is compressed, internal forces and deformations are generated, and the corresponding data are collected through preset sensors, and the deformation and convergence deformation of the square tunnel model (4) under random external loads, as well as the surrounding soil to the square tunnel model (4) Pressure is measured. 2. a kind of prefabricated box culvert top ground traffic load simulation test method according to claim 1 is characterized in that, the calculation of the expansion and contraction amount of the telescoping rod (23) of the deformable pressure bearing device (18) described in S3 Methods include: s1: fully add the soil body into the model box (3), and make it reach a predetermined degree of compaction; s2: Measure the relationship between soil height H, soil density ρ, soil particle specific gravity d _s , soil water content ω, soil void ratio e and vertical compressive stress p under confinement conditions in the model box (3); s3: Calculate the weight γ of each group of soil according to the formula γ=ρg, and draw the relationship curve between the void ratio e and the vertical compressive stress p of each group of soil in the confined compression test, according to the formula Calculate the compression coefficient a of each group of soil; s4: Mesh the soil on the horizontal plane where the axis of the square tunnel model (4) is located during the test, and pre-set the total stress σ _j of the soil at the intersection of each vertical and horizontal line. The value of σ _j is the same as that in the actual working condition equal in size; s5: Calculate the soil in the model box (3), calculate the self-weight stress σ _zj of the soil at this place, calculate the additional stress p _j of the soil at this place, and finally calculate the settlement value s _j of the soil at this place; s6: the settlement value s _j of each soil mass obtained based on s5, that is, the deformation value of the corresponding rotating steel plate (22) above the soil mass; measure the pitch P of the telescopic rod (23) around the deformable pressure-bearing device (18), Calculate the number of rotations of the telescopic rod (23) at this place according to the formula s7: Based on the number of rotations of each telescopic rod (23) obtained in s6 All telescopic rods (23) are adjusted, and then tested according to the test requirements. 3. the ground traffic load simulation test method above a kind of prefabricated box culvert according to claim 1, is characterized in that, described model box (3) opening is placed in the reaction force steel frame upwards, and described reaction force The steel frame is composed of a base (1) and frame rods (2) vertically fixed at the four corners of the base (1) respectively; a square tunnel model (4) placed front and back is arranged in the model box (3), and the square tunnel model (4 ) is equipped with a monitoring device inside; the bottom of the box is provided with a water injection pipe (5); the front side of the box is provided with a model slide rail (9), and there is a model sleeve (10) along the front and rear direction on the model slide rail (9) The frame bar (2) is provided with a lifting device (11) that can move up and down, and an integral loading device is vertically provided on the lifting device (11), and a plurality of split loading devices are distributed in a rectangular array below the integral loading device. The body loading device is placed above the soil layer; the lifting device (11) drives the overall loading device to move up and down, and loads are increased and decreased on multiple split loading devices, and the soil layer is simulated to be loaded and unloaded in stages. The pressure changes produced by the square tunnel model (4) in the soil layer were monitored. 4. the ground traffic load simulation test method above a kind of prefabricated box culvert according to claim 3 is characterized in that, the front side of described model box (3) is made of the plexiglass plate (24) of left and right sides and middle The upper and lower ends of the middle steel plate (25) are fixed on the model box (3). There is a round hole in the middle of the middle steel plate (25), and the square tunnel model (4) is placed in the model box through the round hole. Inside the box (3); the front side of the middle steel plate (25) is hinged with a door panel (26), and the four corners of the door panel (26) are all fastened by bolts to make the door panel (26) close to the model box (3), Close the round hole. 5. the ground traffic load simulation test method above a kind of prefabricated box culvert according to claim 3, is characterized in that, described square tunnel model (4) is the cylinder that is made up of a plurality of arc-shaped tunnel segments, box A horizontal steel plate (6) is fixed at the upper and lower ends of the rear side of the body, a vertical steel plate (7) is fixed between the two horizontal steel plates (6), and a horizontal jack (8) is fixed in the middle of the front side of the vertical steel plate (7). ), the front end of the horizontal jack (8) is fixed on the square tunnel model (4). 6. the ground traffic load simulation test method above a kind of prefabricated box culvert according to claim 3 is characterized in that, the front side of described model box (3) is provided with an L-shaped bracket (27), the L-shaped bracket There is a cross bar (28) between (27) and vertical steel plate (7), and cross bar (28) is placed in the square tunnel model (4) and is concentric with square tunnel model (4); Cross bar (28) ) is evenly distributed on the upper circumference and has a plurality of laser range finders (29) distributed in front and rear arrays, and the L-shaped support (27), cross bar (28), and laser range finders (29) jointly form a monitoring device. 7. the ground traffic load simulation test method above a kind of prefabricated box culvert according to claim 3, is characterized in that, described model sleeve (10) is made up of a plurality of curved plates (30) that are evenly distributed around the circumference, corresponding to The adjacent curved plates (30) are occluded by tongue and groove seams, the length of the model sleeve (10) is 1.1 times that of the square tunnel model (4), and the inner diameter of the model sleeve (10) is the same as the outer diameter of the square tunnel model (4) The model slide rail (9) is a steel frame shaped like an upside-down fish belly, and the model sleeve (10) is placed in the model slide rail (9). 8. The ground traffic load simulation test method above a prefabricated box culvert according to claim 3, characterized in that, the lifting device (11) consists of a hollow lifting sleeve (36) sleeved on the pole (2). ) and the horizontal beam slide rail (37) that connects each hollow lifting sleeve (36); The upper end face is flush, and the lower end face is an upwardly inclined slope; a plurality of vertically equidistant bolt holes (39) are arranged on the frame bar (2) with sawtooth (38); the hollow lifting sleeve (36) is inside One side of the sawtooth (38) is hinged with a turning bar (40), and one end of the turning bar (40) seeing the sawtooth (38) is hinged with a depression bar (41), and the lower end of the depression bar (41) is placed between the sawtooth (38) Between, a spring (42) is connected between the upper end of the depression bar (41) and the turning bar (40). 9. a kind of ground traffic load simulation test method above the prefabricated box culvert according to claim 3, is characterized in that, described overall loading device comprises cross-shaped slide rail, large-scale vertical jack (14) and loading plate; Lifting device (11) is provided with cross-shaped slide rail, and cross-shaped slide rail is provided with a large-scale vertical jack (14) that can move forward and backward, left and right, and there is a loading plate below the large-scale vertical jack (14), and the loading plate consists of The upper and lower backing plates (15) and a plurality of I-beams (16) between the two backing plates (15); The vertical T-shaped bar (44) is composed of a C-shaped member (45) fixed at both ends of the T-shaped bar (44), and the C-shaped member (45) is fixedly connected to the horizontal beam slide rail (37) on the corresponding side by bolts On; the upper end of the large vertical jack (14) is fixed below the hollowed-out round platform (43). 10. The ground traffic load simulation test method above a prefabricated box culvert according to claim 9, wherein the split loading device comprises a small vertical jack (17), a deformable pressure bearing device (18) and a partition plate (19); a plurality of small vertical jacks (17) are distributed in a rectangular array on the lower end of the loading plate, and a deformable pressure-bearing device (18) is arranged below each small vertical jack (17); each A box-shaped dividing plate (19) is arranged on the deformable pressure bearing device (18), and the dividing plate (19) wraps the corresponding small vertical jack (17), and the adjacent dividing plate ( 19) are fastened and connected by bolts; the deformable pressure bearing device (18) includes an upper rectangular steel plate (20), and there is a lower rectangular steel plate (21) directly below the upper rectangular steel plate (20). The apex of the upper and lower rectangular steel plates (21) is respectively placed in the middle of the upper rectangular steel plate (20) side length, and a triangular rotating steel plate (22) is hinged on the four sides of the lower rectangular steel plate (21), and the rotating steel plate (22 ) to the horizontal position, the lower rectangular steel plate (21) and four rotating steel plates (22) together form a steel plate as large as the upper rectangular steel plate (20); A telescopic rod (23) is connected to the hinge, and the upper ends of the telescopic rod (23) are all fixed on the upper rectangular steel plate (20). pressure device (18). The outer edge surface of the telescoping rod (23) of the deformable pressure bearing device (18) and the inner edge surface of one end of the ball hinge are thread fit.