CN103616287A - Laboratory model testing device for tunnel excavation - Google Patents

Abstract

The invention discloses an indoor model test device for tunnel excavation, which comprises a model box, a tunnel structure model, a loading device and an excavation device. The model box is composed of a ground groove and an organic glass plate, and the organic glass plate is fixed on the One side of the opening of the trough, the model box is filled with model test filler; the tunnel structure model is poured with rosin material according to the actual tunnel section according to the similar ratio size, and is arranged in the middle of the model box; the loading device is mainly composed of Composed of reaction beams, steel plates and hydraulic jacks, it is set on the top of the model box; the excavation device is mainly composed of heating wires, wires and power switches, and the heating wires are set in the tunnel structure model. The invention facilitates the simulation of the tunnel excavation process in terms of shape and size, the excavation boundary can be well matched with the pre-designed geometric boundary, and the simulated tunnel excavation is more in line with the actual project. The invention has simple structure, convenient operation and low cost Low, easy to popularize and apply.

Description

An indoor model test device for tunnel excavation

technical field

The invention belongs to the technical field of tunnel engineering in geotechnical and underground engineering, and in particular relates to an indoor model test device for tunnel excavation.

Background technique

In recent years, with the large-scale development of my country's highways and their extension to mountainous areas, the proportion of tunnels in the route has become higher and higher, and the problems in the tunnel construction process have become more and more prominent. Using the physical model based on similar theory Test is an important means of researching and analyzing tunnel construction problems at present. At present, the tunnel construction model test is mainly carried out by two methods: one is overloading, that is, the method of "opening the hole first, then loading", and the other is loading first, and then manually excavating the soil according to the designed geometric boundary. body. Method 1 is easy to operate, but it cannot reflect the real force condition of the surrounding rock of the tunnel. Method 2 can simulate the real force condition of the tunnel, but excavating the soil with tools will easily lead to the collapse of the surrounding soil of the excavated tunnel, resulting in the excavation boundary. Does not conform to pre-designed geometric boundaries. On the other hand, due to the inconvenience of operation, the existing model tests basically ignore the role of primary support, which violates the design principles of the new Austrian method adopted in actual engineering, and the test data collected in this way lack scientificity and accuracy. Therefore, there is an urgent need for a test method and equipment that can truly and scientifically simulate tunnel excavation, so as to provide a reliable basis for tunnel construction and surrounding rock stability analysis.

Contents of the invention

In order to overcome the above-mentioned deficiencies in the prior art, the object of the present invention is to provide a tunnel excavation indoor model test device with good accuracy, simple structure, convenient operation, and reliable basis for the construction of tunnel engineering and the stability analysis of surrounding rock. .

In order to achieve the above object, the present invention adopts the following technical solutions: a tunnel excavation indoor model test device, including a model box, a tunnel structure model, a loading device and an excavation device, and the model box is composed of a trough and a plexiglass plate, One side of the trough is provided with an opening, the two ends of the opening are provided with grooves, the plexiglass plate is fixed on one side of the trough opening through the groove, and the model box is filled with a model test filler;

The tunnel structure model is poured according to the actual tunnel section according to the similar ratio size, the tunnel structure model is arranged in the middle of the model box, and the tunnel structure model is made of rosin material;

The loading device is mainly composed of a reaction beam, a steel plate and a hydraulic jack, and is installed on the top of the model box. The reaction beam is fixed on the upper part of the trough by anchor bolts, the steel plate is installed on the top of the model test packing, and the hydraulic jack is installed on the reaction box. Between the force beam and the steel plate;

The excavation device is mainly composed of heating wires, wires and power switches. The heating wires are set in the tunnel structure model, and the power switches are connected in series on the wires and set outside the model box.

The plexiglass plate is colorless transparent glass.

A hole slightly larger than the section of the tunnel is arranged in the middle of the plexiglass plate.

The model test filler is mainly composed of earth material and stone material, and different grades of tunnel surrounding rocks are simulated by adjusting the mix ratio of earth material and stone material.

The heating wires are braided into circular rings whose diameter is smaller than that of the tunnel structure model and arranged at equal intervals in the tunnel structure model.

A wire hole is arranged on the side of the ground trough, and the wire connects the heating wire with the power switch through the wire hole.

The heating wire is made of nickel-chromium material.

The reaction beam is made of I-beam.

The technical scheme adopted in the present invention has the following beneficial effects:

1. Since the tunnel structure model in the present invention is poured from rosin with a low melting point and high strength after cooling, the tunnel excavation process simulation of shape and size can be conveniently carried out by using the present invention.

2. The tunnel structure model is placed in the tunnel model box before loading, which is consistent with the actual force condition of the tunnel. The excavation of the tunnel is simulated by heating and melting with electric heating wires, which avoids the impact of excavation vibration on the surrounding filler. Make the excavation boundary fit well with the pre-designed geometric boundary.

3. During the simulated excavation process, the heating and melting of rosin will make the filler around the tunnel adhere to a thin layer of rosin, which can simulate the shotcrete support after the actual tunnel excavation, which makes the model test closer to the actual project The new Austrian method design principle.

4. The tunnel excavation simulated by the present invention is more in line with the actual project, has good accuracy, simple structure, convenient operation, low cost, and is convenient for popularization and application.

Description of drawings

Fig. 1 is the device structure schematic diagram of the present invention;

Fig. 2 is the tunnel structure model schematic diagram of the present invention;

In the figure: 1. Floor trough; 2. Plexiglass plate; 3. Model test filler; 4. Tunnel structure model; 5. Reaction beam; 6. Steel plate; 7. Hydraulic jack; 8. Heating wire; 9. Conductor; 10. Power switch; 11. Groove; 12. Hole; 13. Wire hole; 14. Anchor bolt.

Detailed ways

The technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and through specific implementation methods.

An indoor model test device for tunnel excavation, including a model box, a tunnel structure model 4, a loading device and an excavation device. The model box is composed of a trench 1 and a plexiglass plate 2, and an opening is arranged on one side of the trench 1. Both ends of the opening are provided with grooves 11, and the plexiglass plate 2 is fixed on one side of the opening of the trough 1 through the groove 11. The thickness of the plexiglass plate 2 is 10-15 mm, and it is colorless and transparent. A hole 12 slightly larger than the section of the tunnel is convenient for observing real-time changes and displacements of fillers around the tunnel structure model.

The model box is filled with a model test filler 3, the model test filler 3 is mainly composed of soil and stone, by adjusting the mix ratio of the soil and stone to simulate different grades of tunnel surrounding rock, the mixing of soil and stone The content of stone in the material is 10% to 70%.

The excavation device is mainly composed of a heating wire 8, a wire 9 and a power switch 10. The heating wire 8 is braided into a ring with a diameter smaller than the tunnel structure model 4 and arranged at equal intervals in the tunnel structure model 4. The power switch 10 is connected in series. The wire 9 is arranged on the outside of the model box; the heating wire 8 is made of nickel-chromium material.

The tunnel structure model 4 is poured with rosin material according to the actual tunnel section according to the similar ratio of 1:50 to 1:80. The model box is filled with soil and stone in layers and compacted. The design height of the model test filler 3 is 1.5 ~2m, when the construction reaches half of the design height of the model test filler 3, put the tunnel structure model 4 in the middle of the model test filler 3, and use the wire 9 to connect the heating wire 8 and the power switch 10 through the wire hole 13 on the side of the ground trough 1 , to form a closed circuit; then fill the remaining soil and stone according to the same construction method.

The loading device is mainly composed of a reaction beam 5, a steel plate 6 and a hydraulic jack 7, and is arranged on the top of the model box. The two reaction beams 5 are fixed on the upper part of the trench 1 through the anchor bolts 14, the steel plate 6 with a thickness of 12-14mm is arranged on the top of the model test packing 3, and the hydraulic jack 7 is arranged between the reaction beam 5 and the steel plate 6;

The specific test steps are as follows:

1. First, refer to the section size of the designed tunnel structure, determine the diameter of the tunnel structure model 4 and the size of the model box according to the similarity ratio of 1:50 to 1:80, then build the ground groove 1, and place the plexiglass plate 2 through the groove 11 It is fixed on the opening side of the trough 1, and the reaction beam 5 is fixed on the upper part of the trough 1 through the anchor bolt 14;

2. According to the shape and size of the excavated tunnel section, use rosin to pour out the tunnel structure model 4 at a ratio of 1:50 to 1:80. Before pouring, weave the heating wire 8 into a ring with a diameter smaller than the tunnel structure model 4 and place them on Tunnel structure model 4;

3. Fill the model test filler 3 into the model box device in layers. The model test filler 3 is composed of soil and stone, and the content of the stone mass is 10% to 70%. Each layer is filled with 15 to 20cm. Machine compaction, when the construction reaches half (0.75-1m) of the design height of the filler (1.5-2m), place the tunnel structure model 4 poured in advance in the middle of the filler, and use the wire 9 to pass through the wire hole 13 and then connect the heating wire 8 Connect with the power switch 10, then continue to fill the model test filler 3 to the design height, and bury the strain gauges, pressure cells and displacement sensors around the tunnel structure model 4;

4. Place the steel plate 6 on the top of the model test packing 3, set a hydraulic jack 7 between the steel plate 6 and the reaction frame 5, lift the hydraulic jack 7 to pressurize the model test packing 3 in the model box, when loaded to Stop pressurization when the design pressure is 50-100 kPa;

5. Connect each group of wires to the laboratory power supply, turn on the power switch 10 in turn, the heating wire 8 will heat up rapidly, and gradually melt the tunnel structure model 4 from the outside to the inside, thereby simulating the excavation process of the tunnel;

6. Through the plexiglass plate 2, observe the change of the soil-rock mixed filler in the model of the tunnel structure model 4 after melting, and describe and record it in detail, test the stress and displacement through the strain gauge, pressure cell and displacement sensor, and analyze the tunnel perimeter. The stability of the rock and the best timing of the secondary support, the test is completed.

The basic principles and main features of the present invention have been shown and described above. Those skilled in the industry should understand that the present invention is not limited by the above-mentioned embodiments. What are described in the above-mentioned embodiments and the description only illustrate the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will also have Variations and improvements are possible, which fall within the scope of the claimed invention. The protection scope of the present invention is defined by the appended claims and their equivalents.

Claims (8)

1. a tunnel excavation indoor model test device, comprise model casing, tunnel structural model (4), stress model and excavation model, it is characterized in that: described model casing is comprised of geosyncline (1) and poly (methyl methacrylate) plate (2), in geosyncline (1) one side, be provided with opening, the two ends of opening are provided with groove (11), poly (methyl methacrylate) plate (2) is fixed on the one side of geosyncline (1) opening by groove (11), be filled with model test filler (3) in described model casing;

Described tunnel structural model (4) is built and is formed according to ratio of similitude size according to actual tunnel cross section, and described tunnel structural model (4) is arranged at the middle part of model casing, and described tunnel structural model (4) adopts rosin material to make;

Described stress model is mainly comprised of reaction beam (5), steel plate (6) and hydraulic jack (7), be arranged at the top of model casing, described reaction beam (5) is fixed on geosyncline (1) top by anchor bolt (14), steel plate (6) is arranged at model test filler (3) top, and hydraulic jack (7) is arranged between reaction beam (5) and steel plate (6);

Described excavation model is mainly comprised of heating wire (8), wire (9) and power switch (10), and heating wire (8) is arranged in tunnel structural model (4), and power switch (10) is connected on wire (9) and goes up and be arranged at model casing outside.

2. tunnel excavation indoor model test device according to claim 1, is characterized in that: described poly (methyl methacrylate) plate (2) is colourless transparent glass.

3. tunnel excavation indoor model test device according to claim 1, is characterized in that: described poly (methyl methacrylate) plate (2) middle part is provided with a hole slightly larger than tunnel cross section (12).

4. tunnel excavation indoor model test device according to claim 1, is characterized in that: described model test filler (3) is mainly comprised of earth material and building stones, recently simulates the tunnel surrounding of different brackets by adjusting the cooperation of earth material and building stones.

5. tunnel excavation indoor model test device according to claim 1, is characterized in that: described heating wire (8) is woven into annulus spaced set that diameter is less than tunnel structural model (4) in tunnel structural model (4).

6. tunnel excavation indoor model test device according to claim 1, is characterized in that: described geosyncline (1) side is provided with wire guide (13), and wire (9) is connected heating wire (8) by wire guide (13) with power switch (10).

7. tunnel excavation indoor model test device according to claim 1, is characterized in that: described heating wire (8) adopts nickel chromium triangle material to make.

8. tunnel excavation indoor model test device according to claim 1, is characterized in that: described reaction beam (5) adopts joist steel to process.

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