Cold region tunnel freezing test device for simulating ventilation and seepage effects

Abstract

The utility model belongs to the technical field of cold region tunnel freezing simulation devices, and discloses a cold region tunnel freezing test device for simulating ventilation and seepage effects, which comprises a box body, a tunnel model arranged in the box body, a water inlet arranged at the bottom of the box body, a constant-temperature water tank connected with the box body and arranged on a lifting frame, and a temperature measuring probe arranged in the box body, an anemometer is arranged in the tunnel model, an annular drain pipe is arranged on the tunnel model, a bottom drain pipe is arranged at the bottom, measuring cups are arranged at two ends of the bottom drain pipe, the tunnel model corresponds to an air outlet of the fan, and an air inlet of the fan is connected with the refrigeration house. The device can simulate and reproduce the freezing process of the tunnel drainage system and the surrounding rock in the cold region under the action of ventilation and seepage, and can reveal the freezing evolution mechanism of the drainage system and the surrounding rock under the action of ventilation and underground water seepage by monitoring the change of parameters such as temperature and seepage flow at different positions of the surrounding rock along with time; and a solid theoretical basis is provided for cold region tunnel freezing damage prevention and control.

Description

Technical Field

[0001] The utility model belongs to the technical field of tunnel freezing simulation devices in cold regions, in particular to a tunnel freezing test device in cold regions which simulates ventilation and seepage effects. Background Art

[0002] As my country's transportation construction continues to move towards extreme environments, the number of tunnels in high-altitude and high-latitude areas is increasing, and the problem of tunnel frost damage is becoming increasingly prominent, seriously affecting the normal operation and driving safety of tunnels. The occurrence of frost damage is inseparable from the participation of low temperature environments and groundwater. Generally speaking, the temperature field inside tunnels in cold regions is mainly affected by the external environment and the geothermal heat of the surrounding rock. When natural wind flows blow cold air from outside the tunnel into the tunnel, it will change the distribution of the temperature field inside the tunnel. Under the condition of continuous exchange between the cold air outside the tunnel and the geothermal heat of the surrounding rock, if the temperature of the surrounding rock drops to the critical freezing point, frost damage may occur. In addition, groundwater is the source of tunnel frost damage. If there is no water in the surrounding rock, the tunnel will not suffer frost damage even if the external ambient temperature is very low. At present, most tunnels use a "waterproofing and drainage combined" waterproofing and drainage system. Groundwater in the surrounding rock continuously flows out through the drainage pipes behind the lining. This process will inevitably cause heat flow and affect the temperature field of the surrounding rock.

[0003] However, current research results on cold-region tunnels mostly focus on monitoring the ambient temperature inside and outside the tunnel, solving heat transfer equations, and temperature fields and sensitive factors under the influence of multiple factors. There is less research on the interaction mechanism between the seepage field and the temperature field. In particular, the freezing mechanism of surrounding rock in cold-region tunnels under the action of ventilation and groundwater seepage is still unclear. Some scholars have conducted research on the impact of seepage and ventilation on the surrounding rock temperature field, but they have also ignored the detailed structures of the tunnel, such as the annular and longitudinal drainage systems, and cannot achieve a true simulation of the drainage and freezing process of cold-region tunnels.

[0004] To solve the above problems, the present invention proposes a test system and test method for simulating the freezing of drainage systems and surrounding rocks in cold-region tunnels under ventilation and seepage. The system can reveal the freezing evolution mechanism of drainage systems and surrounding rocks under the action of ventilation and groundwater seepage, provide a solid theoretical basis for the prevention and control of freezing damage in cold-region tunnels, and promote the development of cold-region tunnels in a safe and reliable direction. Summary of the Invention

[0005] The purpose of the utility model is to overcome the deficiencies of the prior art and provide a cold region tunnel freezing test device which simulates ventilation and seepage effects.

[0006] The purpose of the utility model is achieved through the following technical solutions: a cold region tunnel freezing test device simulating ventilation and seepage, comprising a box body with a box cover on the top, a tunnel hole opened at the center of two opposite sides of the box body, a tunnel model arranged in the box body, and both ends of the tunnel model are sealedly connected to the tunnel hole;

[0007] The bottom of the box is provided with a water inlet connected with a heat preservation water pipe, and the other end of the heat preservation water pipe is connected with a constant temperature water tank arranged on a lifting frame.

[0008] Temperature measuring probes are arranged in the box and outside the tunnel model, and the temperature measuring probes are intermittently arranged along the circumferential direction and longitudinal direction of the tunnel model; an anemometer is fixedly arranged in the tunnel model, and the temperature measuring probes and the anemometer are connected with a data display.

[0009] The surface of the box is wrapped with heat preservation cotton; and the inner top surface and the inner bottom surface of the box are sequentially paved with water permeable plates and geotextiles.

[0010] Circumferential drainage pipes are intermittently arranged along the circumferential direction of the outer periphery of the tunnel model, a plurality of holes penetrating the inside and outside of the circumferential drainage pipes are formed in the surface of the circumferential drainage pipes, and the surface of the circumferential drainage pipes is wrapped with sandpaper; bottom drainage pipes are longitudinally arranged at the bottom of the tunnel model, both ends of the bottom drainage pipes extend to the outside of the box, and measuring cups are arranged at both ends of the bottom drainage pipes, and the bottom drainage pipes are connected with the circumferential drainage pipes.

[0011] One end of the tunnel model corresponds to the air outlet of a fan, and the air inlet of the fan is connected with a cold storage; and the temperature of the cold storage is adjustable.

[0012] Further, the box is filled with river sand with different particle sizes.

[0013] Further, the two ends of the tunnel model are connected with the tunnel hole in a glass glue sealing connection mode.

[0014] Further, a valve is arranged on the heat preservation water pipe.

[0015] Further, the temperature measuring probes are arranged in three groups along the longitudinal direction of the tunnel model, each group is arranged at the upper, lower, left and right positions in the circumferential direction of the tunnel model at non-equal intervals, and the closer to the temperature measuring probes of the tunnel model, the smaller the arrangement interval.

[0016] Further, the circumferential drainage pipes are arranged in two roots, and are alternately arranged with the temperature measuring probes in the longitudinal direction of the tunnel model.

[0017] The utility model discloses a tunnel model and a box body, which are connected with each other in a sealing mode, and the box body is filled with river sand with different particle sizes. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 It is the front view of the device of the utility model;

[0019] Figure 2 It is the section side view of the device of the utility model in the longitudinal central axis direction;

[0020] Figure 3 It is the structure schematic view of the tunnel model, the ring drainage pipe and the bottom drainage pipe of the utility model;

[0021] In the drawing: 1-lifting frame, 2-constant temperature water tank, 3-heat preservation water pipe, 4-data acquisition system, 5-temperature measuring probe, 6-box, 7-heat preservation cotton, 8-geotextile, 9-permeable board, 10-water inlet, 11-tunnel model, 12-ring drainage pipe, 13-anemometer, 14-fan, 15-cold store, 16-bottom drainage pipe, 17-measuring cup. DETAILED DESCRIPTION

[0022] The technical scheme of the utility model will be described in further detail below in combination with the drawings, but the protection scope of the utility model is not limited to the following.

[0023] Example 1

[0024] Reference Figure 1-3 A cold region tunnel freezing test device for simulating the effects of ventilation and seepage, comprising a box 6 provided with a box cover at the top, tunnel holes are formed at the centers of two opposite sides of the box 6, a tunnel model 11 is arranged in the box 6, and the two ends of the tunnel model 11 are sealingly connected with the tunnel holes respectively.

[0025] It should be pointed out that the tunnel model 11 in the utility model refers to: under the condition of meeting the similar ratio, referring to the relevant contents in the book of "Similar Theory and Model Test of Civil Engineering", a lining model meeting the prototype is made based on system test. The box 6 in the utility model is welded by 5mm thick steel plates.

[0026] A water inlet 10 is formed at the bottom of the box 6, the water inlet 10 is connected with the heat preservation water pipe 3, the other end of the heat preservation water pipe 3 is connected with the constant temperature water tank 2, and the constant temperature water tank 2 is arranged on the lifting frame 1; by adjusting the height of the lifting frame 1, the simulation of different water head heights is realized, different temperature water can be stored in the constant temperature water tank 2, the water flowing out from the constant temperature water tank 2 flows through the permeable board, the geotextile and the surrounding rock from the heat preservation water pipe 3 and the water inlet 10, and then enters the box 6. Thus, the simulation of water head height and water flow temperature is realized.

[0027] The temperature measuring probe 5 is arranged in the box 6 and outside the tunnel model 11, and is arranged intermittently along the circumferential direction and the longitudinal direction of the tunnel model 11; the anemometer 13 is fixedly arranged in the tunnel model 11, and the temperature measuring probe 5 and the anemometer 13 are connected with the data display 4; the temperature measuring probe 5 mainly monitors the temperature of surrounding rock, the temperature of air flow at a tunnel entrance, the temperature of water flow at the bottom of the model and the temperature of the external environment.

[0028] The box surface of the box 6 is wrapped with thermal insulation cotton 7 to avoid the influence of the ambient temperature on the temperature field of the surrounding rock, and preferably, double-layer thermal insulation cotton is adopted; the inner top surface and the inner bottom surface of the box are sequentially laid with a water permeable plate 9 and a geotextile 8;

[0029] The circumferential drainage pipe 12 is intermittently arranged outside the periphery of the tunnel model 11, a plurality of holes penetrating the inside and outside of the circumferential drainage pipe 12 are formed on the surface of the circumferential drainage pipe 12, and the surface of the circumferential drainage pipe 12 is wrapped with sand cloth; the bottom drainage pipe 16 is longitudinally arranged at the bottom of the tunnel model 11, both ends of the bottom drainage pipe 16 extend to the outside of the box 6, and the measuring cup 17 is arranged at both ends of the bottom drainage pipe 16, so as to monitor the seepage flow of the longitudinal drainage system at the bottom of the tunnel with time. The bottom drainage pipe 16 is connected with the circumferential drainage pipe 12; preferably, the circumferential drainage pipe 12 and the bottom drainage pipe 16 are connected through a four-way connector.

[0030] One end of the tunnel model 11 corresponds to the air outlet of the fan 14, and the air inlet of the fan 14 is connected with the cold storage 15. The fan 14 blows the cold air in the cold storage 15 into the tunnel model 11, and the fan can provide different air speeds at different gears, the air speed of the cold air at the tunnel entrance is monitored through the anemometer 13, and the simulation of different air speeds and air temperatures is realized.

[0031] Further, the box 6 is filled with river sand with different particle sizes outside the tunnel model 11. The river sand is used for simulating surrounding rock, and different particle sizes of river sand are prepared according to the actual surrounding rock situation of the project based on the permeability coefficient. The two ends of the tunnel model 11 are connected to the tunnel hole in a glass glue sealing connection mode. The heat preservation water pipe 3 is provided with a valve. The temperature measuring probe 5 is arranged in three groups along the longitudinal direction of the tunnel model 11, each group is arranged in the upper, lower, left and right directions of the tunnel model 11 in a non-equidistant manner along the circumferential direction of the tunnel model 11, and the closer to the tunnel model 11, the smaller the arrangement interval of the temperature measuring probe. The circumferential drainage pipe 12 is provided with two pipes, which are arranged alternately with the temperature measuring probe 5 in the longitudinal direction of the tunnel model 11.

[0032] Example 2

[0033] Based on the example 1, referring to Figure 1-3 The application also provides a test method matched therewith:

[0034] Using a combination of on-site and similar materials, a scaled model was constructed. Circumferential drainage pipes were installed to conduct model tests on freezing of the surrounding rock and drainage system of a cold-region tunnel under varying ventilation (wind speed and temperature) and seepage (water head height and water temperature) factors. By monitoring dynamic surrounding rock temperature and seepage volume, the evolution of the temperature field in the surrounding rock and drainage system, as well as the frost heave development mechanism under ventilation and seepage conditions, were analyzed. Drainage system parameters, such as drainage pipe spacing, size, and layout, were also varied to investigate their impact on the development of surrounding rock freezing.

[0035] Specific implementation plan of the test:

[0036] (1) Based on the test site and target project, a scaled model is constructed by combining on-site materials and similar materials to make the physical phenomena in the prototype and the model similar. Similar surrounding rock materials that meet the target working conditions are configured, and a tunnel model that meets similar requirements is cast.

[0037] (2) Before the formal test, a preliminary test is carried out to test the feasibility of the test plan. The main purpose is to test whether the preset water head height and wind speed meet the test requirements, and to preliminarily determine the time required for the surrounding rock to freeze.

[0038] (3) The variables in the test are wind speed, wind temperature, water head height, and water temperature. In order to compare the test results under different test conditions, during the test, real-time data such as temperature and seepage volume at different locations of the surrounding rock are collected. The duration of negative temperature, wind speed, wind temperature, water head height, water temperature and other parameters are integrated to simulate the development and evolution mechanism of frost heave of the surrounding rock and drainage system under ventilation and seepage conditions.

[0039] (4) After the freezing is completed in each working condition, the seepage circulation is allowed to continue for a period of time so that the surrounding rock temperature field can return to its initial state.

[0040] (5) Based on orthogonal analysis, the influence of wind temperature, wind speed, water head, water temperature, drainage pipe spacing and drainage pipe size on the drainage system and surrounding rock freezing is comprehensively considered. Combined with the above test results, the sensitivity ranking of each factor on the freezing of surrounding rock in cold-region tunnels is given.

[0041] The above description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein and should not be construed as excluding other embodiments. Instead, the present invention can be used in various other combinations, modifications, and environments and can be modified within the scope of the concept described herein through the above teachings or techniques or knowledge in the relevant fields. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention are intended to be protected by the claims appended hereto.

Claims

1. A cold region tunnel freezing test device simulating ventilation and seepage, characterized in that: It comprises a box body (6) with a box cover on the top, tunnel holes are opened at the centers of two opposite sides of the box body (6), a tunnel model (11) is arranged in the box body (6), and both ends of the tunnel model (11) are sealedly connected to the tunnel holes; The bottom of the box body (6) is provided with a water inlet (10), the water inlet (10) is connected to a heat-insulating water pipe (3), the other end of the heat-insulating water pipe (3) is connected to a constant-temperature water tank (2), and the constant-temperature water tank (2) is arranged on the lifting frame (1); A temperature measuring probe (5) is provided inside the box (6) and outside the tunnel model (11), and the temperature measuring probe is intermittently provided along the circumferential direction and the longitudinal direction of the tunnel model (11); an anemometer (13) is fixedly provided inside the tunnel model (11), and the temperature measuring probe (5) and the anemometer (13) are both connected to a data display (4); The box surface of the box body (6) is wrapped with thermal insulation cotton (7); the inner top surface and inner bottom surface of the box body are successively paved with a permeable board (9) and a geotextile (8); An annular drainage pipe (12) is intermittently provided on the outer periphery of the tunnel model (11), and a plurality of holes penetrating the inside and outside of the annular drainage pipe (12) are provided on the surface of the annular drainage pipe (12), and the surface of the annular drainage pipe (12) is wrapped with emery cloth; a bottom drainage pipe (16) is longitudinally provided at the bottom of the tunnel model (11), and both ends of the bottom drainage pipe (16) extend to the outside of the box (6), and measuring cups (17) are provided at both ends of the bottom drainage pipe (16), and the bottom drainage pipe (16) is connected to the annular drainage pipe (12); One end of the tunnel model (11) corresponds to the air outlet of the fan (14), and the air inlet of the fan (14) is connected to the cold storage (15).

2. A cold region tunnel freezing test device simulating ventilation and seepage according to claim 1, characterized in that: The inside of the box (6) and the outside of the tunnel model (11) are filled with river sand of different particle sizes.

3. The cold region tunnel freezing test device simulating ventilation and seepage according to claim 1 is characterized in that: The two ends of the tunnel model (11) are sealed with the tunnel hole using glass glue.

4. The cold region tunnel freezing test device simulating ventilation and seepage according to claim 1 is characterized in that: The heat-insulating water pipe (3) is provided with a valve.

5. The cold region tunnel freezing test device simulating ventilation and seepage according to claim 1 is characterized in that: The temperature measuring probes (5) are arranged in three groups along the longitudinal direction of the tunnel model (11), and each group is arranged at unequal intervals in the upper, lower, left, and right directions along the circumferential direction of the tunnel model (11), and the closer the temperature measuring probes are to the tunnel model (11), the smaller the arrangement interval is.

6. The cold region tunnel freezing test device simulating ventilation and seepage according to claim 5, characterized in that: Two annular drainage pipes (12) are provided, and are arranged alternately with the temperature measuring probes (5) in the longitudinal direction of the tunnel model (11).

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