Energy-absorbing and heat-insulating segmented cemented honeycomb material as well as preparation method and application of energy-absorbing and heat-insulating segmented cemented honeycomb material

Abstract

The invention discloses an energy-absorbing and heat-insulating segmental cemented honeycomb material as well as a preparation method and application thereof, and belongs to the technical field of mining engineering. The energy-absorbing and heat-insulating segmental cementation honeycomb material is obtained by sealing an external window of the array honeycomb structure bracket with a cementation material; wherein each honeycomb unit of the array honeycomb structure is of a hexagonal arc-shaped structure in which three concave edges and three convex edges are alternately arranged. According to the invention, by improving a conventional honeycomb unit, strain hardening of the energy-absorbing and heat-insulating segmental cemented honeycomb material can be realized, so that the energy-absorbing and heat-insulating segmental cemented honeycomb material has the characteristic of ultrahigh energy absorption. When the composite material is applied to construction of a deep roadway, efficient heat insulation can be achieved through low heat conductivity of air, heat convection between the ground temperature and the structure of the deep roadway is weakened, the problem that traditional materials are difficult to adapt to deep high stress and high-temperature coupling degradation is fundamentally solved, the stability of deep roadway surrounding rocks can be guaranteed, and the utilization rate of the section of the roadway can be further increased.

Description

Technical Field

[0001] The present invention belongs to the technical field of mining engineering, and in particular relates to an energy-absorbing and heat-insulating segmented cemented honeycomb material and a preparation method and application thereof. Background Art

[0002] Deep tunnel engineering is a key development direction in modern mining technology. With the continuous development of mineral resources, deep mines are becoming increasingly common. However, deep tunnel engineering faces complex geological environments and extreme physical conditions, such as high ground stress and high temperatures, which place higher demands on tunnel stability and safety. Support and insulation technologies are key engineering measures in the construction and maintenance of deep tunnels, directly impacting mine safety, operational efficiency, and the health and comfort of miners.

[0003] Despite the proposals for optimizing various support materials and structures to control the stability of surrounding rock in deep tunnels, numerous technical challenges remain. For example, while a high-strength anchor-cable synergistic support system significantly improves the overall strength of the surrounding rock, it cannot avoid localized crushing caused by stress concentration. While shotcrete can effectively enhance the crack resistance of surface-fragmented surrounding rock, its brittle nature makes it difficult to adapt to the large deformation requirements of the surrounding rock. Furthermore, high ground temperatures exist in deep tunnels. Under the coupled effects of high ground stress and high ground temperature, the material is prone to thermal-mechanical coupling degradation, ultimately leading to the progressive failure of the support system. Traditional tunnel support structures often struggle to simultaneously address the dual effects of high stress and high temperature, making it difficult to coordinate the insulation and support functions. For example, installing insulation boards or laying insulation layers on tunnel walls can isolate heat by utilizing the material's low thermal conductivity, but the material's insufficient strength makes it susceptible to damage under high stress. While phase-change materials can regulate tunnel temperatures by absorbing heat, their poor cyclic stability, high material cost, and insufficient bonding strength with the surrounding rock limit their practical application. Furthermore, existing insulation materials are often designed as an additional layer separate from the supporting structure, resulting in reduced tunnel cross-sectional utilization and significantly weakening overall insulation performance due to interfacial thermal bridge effects.

[0004] Therefore, there is an urgent need to develop a new support and insulation method that can not only meet the high stress bearing requirements but also effectively isolate high temperature heat damage, so as to achieve safe, stable and efficient operation of deep tunnel projects. Summary of the Invention

[0005] The purpose of the present invention is to provide an energy-absorbing and heat-insulating segmented cemented honeycomb material, and its preparation method and application. The present invention has developed an integrated tunnel support material with ultra-high energy absorption and high-efficiency heat insulation from a new perspective of structural modification. This material improves conventional honeycomb units to achieve strain hardening, giving the material ultra-high energy absorption characteristics. It also utilizes the low thermal conductivity of air to achieve high-efficiency heat insulation, weakening the heat convection between the ground temperature and the structure in deep tunnels. This fundamentally breaks through the problem that traditional materials are difficult to apply to deep high stress and high temperature coupled degradation, can ensure the stability of the surrounding rock of deep tunnels, and can further expand the utilization rate of the tunnel section.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] One of the technical solutions of the present invention is to provide an energy-absorbing and heat-insulating segmented bonded honeycomb material, which is obtained by sealing the external windows of an array honeycomb structure support with the bonding material;

[0008] The honeycomb unit of the array honeycomb structure is a hexagonal arc structure with three inner concave edges and three outer convex edges arranged alternately;

[0009] The inner concave edge and the outer protruding edge are composed of an equal number of one or more segments of equal length. The length of the connecting segment connecting adjacent honeycomb structure layers is the same as the length of the inner concave edge or the outer protruding edge single segment, and the nodes of each segment are connected.

[0010] The schematic diagram of the connection between the honeycomb units and adjacent honeycomb structure layers of the array honeycomb structure of the present invention is shown in FIG. Figure 1 .

[0011] When the segmented bonded honeycomb material of the present invention is destroyed, its structure can disperse the stress at the time of destruction layer by layer, avoiding overall buckling and crushing. Its deformation characteristics are different from those of ordinary bonding materials and honeycomb structures. There is no strain softening and post-peak crushing. It exhibits wavy strain hardening characteristics under conditions of continuous displacement loading and has ultra-high energy absorption characteristics. And because the thermal conductivity of the air in the honeycomb structure pores in the segmented bonded honeycomb material is much lower than that of the bonding wall, under the obstruction of the bonding wall between different honeycomb pores, heat convection is difficult to transfer to the outside of the pores, resulting in more heat propagating along the wall bonding medium. Therefore, it exhibits higher thermal insulation performance. And the thermal insulation performance of such special-shaped structures is quantified by defining the heat transfer limit height, where the heat transfer limit height is defined as the minimum thickness required for a sample with a special-shaped structure to completely block heat transfer under specific thermal boundary conditions (such as constant temperature difference or heat flow).

[0012] Technically, the present invention's segmented, bonded honeycomb material for energy absorption and heat insulation in deep tunnels addresses the bottlenecks of currently used support structures, which are prone to brittle failure, unable to balance long-term load-bearing and dynamic energy absorption requirements, and difficult to adapt to the high-stress conditions of deep tunnels. It also addresses the shortcomings of deep tunnel insulation materials, such as insufficient mechanical properties, poor cyclic stability, and insufficient bonding strength with the surrounding rock. It also addresses the current design of separate tunnel support structures and insulation materials, resulting in low tunnel section utilization. From a new perspective on structural modification, the invention develops an integrated energy absorption and heat insulation support structure, achieving strain hardening, ultra-high energy absorption, and highly efficient heat insulation properties, effectively resisting the long-term effects of deep, high-stress surrounding rock and its degradation coupled with high temperatures.

[0013] In engineering, the present invention's segmented, bonded honeycomb material for deep tunnel energy absorption and insulation abandons the previous design method of separating support structures from insulation materials. Instead, it develops an integrated energy absorption and insulation support structure (3D-printed honeycomb structure + material casting). This allows for rapid construction of deep tunnel support and insulation structures, improving tunnel cross-section utilization. Furthermore, compared to insulation materials like phase change materials and aerogels, the cost is significantly reduced.

[0014] Preferably, the bracket is made of resin.

[0015] Preferably, the cementitious material is a set cement slurry.

[0016] Preferably, the number of segments of the inner concave edge or the outer protruding edge is 2 to 4; and the segments and the connecting segments are cylindrical or rod-shaped.

[0017] The second technical solution of the present invention is to provide a method for preparing the above-mentioned energy-absorbing and heat-insulating segmented bonded honeycomb material, comprising the following steps:

[0018] An array honeycomb structure bracket is prepared by 3D printing, and then the adjusted flowable adhesive material is sprayed in batches and hung on the surface of the array honeycomb structure bracket. After each spraying, the material is shaped and then sprayed again until the flowable adhesive material seals the surface of the array honeycomb structure bracket. After drying, the energy-absorbing and heat-insulating segmented adhesive honeycomb material is obtained.

[0019] Preferably, when the flowable binder material is cement slurry, the drying method is curing.

[0020] The third technical solution of the present invention is to provide an application of the above-mentioned energy-absorbing and heat-insulating segmented bonded honeycomb material in the construction of deep tunnels.

[0021] The fourth technical solution of the present invention is to provide an application of the above-mentioned energy-absorbing and heat-insulating segmented bonded honeycomb material in the construction of aviation thermal protection systems, earthquake-resistant and energy-saving buildings or nuclear reactor protection structures.

[0022] The beneficial technical effects of the present invention are as follows:

[0023] By improving conventional honeycomb units, this invention achieves strain hardening of energy-absorbing and heat-insulating segmented cemented honeycomb materials, endowing them with ultra-high energy absorption properties. When applied to deep tunnel construction, this material leverages the low thermal conductivity of air for efficient insulation, reducing heat convection between the ground temperature and the structure. This fundamentally overcomes the difficulty of traditional materials in adapting to the high stress and high temperature coupled degradation at depth, ensuring the stability of the surrounding rock in deep tunnels and further increasing the utilization rate of the tunnel cross-section.

[0024] This invention provides a new approach for the design of integrated ultra-high energy absorption and thermal insulation materials. Its future adaptability is not limited to underground engineering, but also demonstrates its performance potential and application prospects in the fields of aviation thermal protection systems, earthquake-resistant energy-saving buildings, and nuclear reactor protection structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the connection between the honeycomb units of the array honeycomb structure and adjacent honeycomb structure layers in the present invention.

[0026] Figure 2 This is a flow chart for preparing the segmented bonded honeycomb scaffolds in Comparative Examples 1 to 4.

[0027] Figure 3 The absorbed energy of the test pieces prepared in Example 1 and Comparative Examples 1 to 4 is shown in FIG. 1 , wherein A is the stress-strain curve and B is the energy-strain curve.

[0028] Figure 4 Schematic diagram of the arrangement of temperature measurement points when measuring the thermal insulation coefficient of the array honeycomb structure in the present invention.

[0029] Figure 5 It is the temperature at the same measuring line of each test piece prepared in Example 1 and Comparative Examples 1 to 4 measured according to the thermal insulation coefficient measurement method of the present invention, wherein A is the measurement result of Example 1, Comparative Example 1 and Comparative Example 2, and B is the measurement result of Comparative Example 2, Comparative Example 3 and Comparative Example 4.

[0030] Figure 6 The maximum heat transfer heights of the test pieces prepared in Example 1 and Comparative Examples 1 to 4 were measured according to the thermal insulation coefficient measurement method of the present invention. DETAILED DESCRIPTION

[0031] Various exemplary embodiments of the present invention are now described in detail. This detailed description should not be considered as a limitation of the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terms used in the present invention are only for describing specific embodiments and are not intended to limit the present invention.

[0032] It should be pointed out that the matters not described in detail in the present invention are conventional operating means in this field and are not the focus of the present invention.

[0033] In addition, for numerical ranges in the present invention, it is understood that each intervening value between the upper and lower limits of the range is also specifically disclosed. Each smaller range between any stated value or stated range, and any other stated value or intervening value in the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains. Although preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present invention.

[0035] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0036] The test pieces prepared in the embodiments and comparative examples of the present invention are limited to laboratory measurements, and the material size can be enlarged in actual engineering applications.

[0037] Example 1

[0038] Preparation of pure cement bonded specimens:

[0039] CPC42.5 cement was used to prepare cement slurry at a water-cement ratio of 0.5 by stirring at 500 rpm for 5 minutes. Specimens of 90 mm × 90 mm × 60 mm were prepared using a mold and cured at 25°C and 95% relative humidity for 28 days to obtain pure cement-bonded specimens.

[0040] Comparative Example 1

[0041] Preparation of energy-absorbing and heat-insulating segmented bonded honeycomb specimens:

[0042] A segmented honeycomb structure was designed using 3D modeling software. The honeycomb units were three-segment regular hexagons, each 1.5 mm long. The connecting segments between adjacent honeycomb layers were 1.5 mm long and rod-shaped, with a side length of 0.4 mm. Each segment was connected at the nodes. A 90 mm × 90 mm × 60 mm honeycomb structure was printed using a resin material using photocurable 3D printing with a precision of 0.1 mm. A bonding slurry was prepared by stirring CPC42.5 cement at a water-cement ratio of 0.5 at 500 rpm for 5 minutes. This slurry was sprayed onto the exterior surface of the 3D-printed honeycomb structure. Multiple spraying cycles were performed, ensuring that the previous spraying cycle was completed before the next spraying cycle was completed, until the honeycomb windows were sealed. The energy-absorbing and heat-insulating segmented bonded honeycomb specimens were cured at 25°C and 95% relative humidity for 28 days.

[0043] Comparative Example 2

[0044] Preparation of energy-absorbing and heat-insulating segmented bonded honeycomb specimens:

[0045] Compared with Comparative Example 1, the cells of the honeycomb structure are hexagonal arcs, the number of segments is 3, the segment length is 1.5 mm, the length of the connecting section of adjacent honeycomb structure layers is 1.5 mm, and the rest are the same as Comparative Example 1.

[0046] Comparative Example 3

[0047] Preparation of energy-absorbing and heat-insulating segmented bonded honeycomb specimens:

[0048] Compared with Comparative Example 2, the segment length is 2.5 mm, the connecting segment length of adjacent honeycomb structure layers is 2.5 mm, and the rest is the same as Comparative Example 2.

[0049] Comparative Example 4

[0050] Preparation of energy-absorbing and heat-insulating segmented bonded honeycomb specimens:

[0051] Compared with Comparative Example 3, the number of segments is 4, and the rest is the same as Comparative Example 3.

[0052] The preparation flow chart of the segmented bonded honeycomb scaffold in Comparative Examples 1 to 4 is shown in Figure 2 .

[0053] The specimens prepared in Example 1 and Comparative Examples 1 to 4 of the present invention were loaded and the absorbed energy at the same displacement was examined. The results are shown in FIG. Figure 3 , where A is the stress-strain curve and B is the energy-strain curve.

[0054] Figure 3It is shown that the segmented honeycomb structure obtained is different from the brittle failure of the common support method after the peak, and shows a wavy strain hardening feature after the peak. This wavy strain hardening shows ultra-high energy absorption characteristics, which is due to the layer-by-layer destruction caused by the layer-by-layer distribution of the segmented honeycomb. And as the honeycomb segment length (Comparative Example 2 and Comparative Example 3) and quantity (Comparative Example 2 and Comparative Example 4) decrease, the overall structure will be densified, the strain hardening characteristics of the segmented bonded honeycomb structure will be enhanced, and the absorbed energy of the segmented bonded honeycomb structure will be increased. And the transformation of the segment shape from a straight line to an arc greatly improves the peak stress and energy of the segmented honeycomb structure (Comparative Example 1 and Comparative Example 2). Compared to Example 1, the present invention can achieve very high energy absorption under the conditions of using very little cement, can reduce the emission of carbon dioxide, and is in line with the concept of green development.

[0055] Determination of thermal insulation coefficient of the test pieces prepared in Example 1 and Comparative Examples 1 to 4 of the present invention:

[0056] Conventional transient and steady-state methods cannot accurately and efficiently measure the thermal insulation coefficient of heterogeneous, heterogeneous structures (such as, but not limited to, bonded honeycomb structures). The inventors have devised a method that can efficiently and accurately quantify the thermal insulation properties of these heterogeneous, heterogeneous structures.

[0057] In engineering, the measurement of material thermal conductivity (which is directly related to the thermal insulation coefficient) is divided into steady-state and transient methods. Although the steady-state method has higher accuracy, it requires the material to reach a state of thermal equilibrium, the measurement time is longer, and it has high requirements for the uniformity and isotropy of the material, and has the disadvantage of being time-consuming; the transient method usually has a fast measurement speed, but the data processing is complex, and it is sensitive to the accuracy of the experimental equipment and the uniformity of the material. It is easily affected by boundary conditions and the external environment, and has the disadvantages of low efficiency and complex operation. Therefore, the present invention defines a limit heat transfer height to quantify the thermal conductivity of such structures, which can accurately and efficiently quantify the thermal conductivity of special-shaped structures (for example, honeycomb structures).

[0058] Thermal insulation coefficient measurements were performed using an infrared camera and a semiconductor heating plate as the heat source. The heat transfer of the segmented, cemented honeycomb structure was monitored using an Optotherm Sentris RD microscopic infrared thermal analysis system, which records infrared data throughout the entire heat transfer process. A high-precision semiconductor heating plate with a temperature control accuracy of 0.01°C was used to simulate the heat source of the deep well surrounding rock, set to 60°C. Once the heat source reached the set temperature, the infrared camera was pre-activated, and the sample was then placed in the center of the heating plate. The experiment lasted at least 25 minutes for each sample to ensure optimal heat transfer.

[0059] The schematic diagram of the temperature measurement point arrangement is shown in Figure 4 .

[0060] The temperature at the same measuring line of each specimen is shown in Figure 5 , wherein A is the measurement results of Example 1, Comparative Example 1 and Comparative Example 2, and B is the measurement results of Comparative Example 2, Comparative Example 3 and Comparative Example 4.

[0061] The maximum heat transfer height of each specimen is shown in Figure 6 .

[0062] Depend on Figure 5 It can be seen that, as a whole, the temperature at the same measuring point increases significantly with the decrease in segment length and number. This indicates that the increase in the honeycomb cavity further improves the thermal insulation performance of the structure, while significantly weakening the thermal convection effect between the honeycomb cavities. The segmented bonded honeycomb structure exhibits good thermal insulation performance during the heat transfer process, mainly due to the low thermal conductivity of the air in the honeycomb cavity. The barrier effect of the bonding wall between the honeycomb pores effectively inhibits the transfer of heat convection to the outside of the pores, causing the heat to propagate mainly along the wall through the bonding medium. Moreover, the honeycomb structure with an arc-shaped segment exhibits higher thermal insulation than the honeycomb structure with a straight segment shape. This is particularly evident at measuring points C and E.

[0063] Figure 6 The results show that compared with the pure cement cast specimens, the heat transfer limit height of the honeycomb structure has decreased to varying degrees. In addition, the honeycomb structure with arc-shaped segments has better thermal insulation properties than the straight honeycomb structure.

[0064] The thermal insulation performance of the structure is quantified by the heat transfer limit height, and the formula is shown in formula (1):

[0065]

[0066] In formula (1), C is the thermal insulation coefficient, the unit is k / W or dimensionless; k is the thermal conductivity, the unit is W / m·K; H max The heat transfer limit height is in m or pixel.

[0067] By non-dimensionalizing formula (1), we can obtain formula (2):

[0068]

[0069] In formula (2), C is the thermal insulation coefficient, which is a dimensionless constant; k and H max The units are unified as W / m·K and m.

[0070] The heat transfer limit height H max It is defined as the minimum thickness required for a sample with a special-shaped structure to completely block heat transfer under specific thermal boundary conditions (such as constant temperature difference or heat flow). max, the heat flow approaches zero. The thermal insulation coefficient comprehensively considers the thermal conductivity of the material and the heat transfer limit height of the sample with a specific structure. The lower the thermal conductivity of the material, the better the thermal insulation performance of the sample; the smaller the heat transfer limit height of the sample with a specific structure, that is, the thinner the sample is, the better the thermal insulation performance. Here, it is necessary to clearly specify the heat transfer limit height H of different samples. max The measurement conditions are the same, that is, the temperature difference or heat flow is the same.

[0071] If we further consider the thermal feedback of the special-shaped structure under different thermal environments, we only need to introduce the convection term on the basis of formula (1), and formula (1) can be rewritten as formula (3):

[0072]

[0073] In formula (3), h is the surface convection heat transfer coefficient; T is the surface ambient temperature difference, in °C.

[0074] Without considering the thermal conductivity of the matrix material constituting the heterogeneous structure, formula (1) can be degenerated into formula (4):

[0075]

[0076] The test specimens prepared in the present invention do not consider the thermal feedback of the special-shaped structure and the thermal conductivity of the matrix material under different thermal environments. The thermal insulation coefficients of each case are obtained by formula (4) and are shown in Table 1.

[0077] Table 1 Thermal insulation coefficient of each specimen

[0078]

[0079] As shown in Table 1, when the segment shape is changed from straight to curved (Comparative Examples 1 and 2), the insulation coefficient increases from 0.00505 to 0.00526; when the segment length is increased (Comparative Examples 2 and 3), the insulation coefficient increases from 0.00526 to 0.00552; and when the number of segments is increased (Comparative Examples 3 and 4), the insulation coefficient increases from 0.00552 to 0.00559. Compared to Example 1 (insulation coefficient 0.00283), the insulation performance is improved by up to 97.5%.

[0080] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. An energy-absorbing and heat-insulating segmented bonded honeycomb material, characterized in that: Obtained by sealing the outer windows of the array honeycomb structure support with a bonding material; The honeycomb unit of the array honeycomb structure is a hexagonal arc structure with three inner concave edges and three outer convex edges arranged alternately; The inner concave edge and the outer protruding edge are composed of an equal number of one or more segments of equal length. The length of the connecting segment connecting adjacent honeycomb structure layers is the same as the length of the inner concave edge or the outer protruding edge single segment, and the nodes of each segment are connected.

2. The energy-absorbing and heat-insulating segmented bonded honeycomb material according to claim 1, characterized in that: The material of the bracket is resin.

3. The energy-absorbing and heat-insulating segmented bonded honeycomb material according to claim 1, characterized in that: The bonding material is solidified cement slurry.

4. The energy-absorbing and heat-insulating segmented bonded honeycomb material according to claim 1, characterized in that: The number of segments of the inner concave edge or the outer protruding edge is 2 to 4; the segments and the connecting segment are cylindrical or rod-shaped.

5. A method for preparing the energy-absorbing and heat-insulating segmented bonded honeycomb material according to any one of claims 1 to 4, characterized in that: The following steps are involved: An array honeycomb structure bracket is prepared by 3D printing, and then the adjusted flowable adhesive material is sprayed in batches and hung on the surface of the array honeycomb structure bracket. After each spraying, the material is shaped and then sprayed again until the flowable adhesive material seals the surface of the array honeycomb structure bracket. After drying, the energy-absorbing and heat-insulating segmented adhesive honeycomb material is obtained.

6. The method for preparing the energy-absorbing and heat-insulating segmented bonded honeycomb material according to claim 5, characterized in that: When the flowable binder material is cement slurry, the drying method is curing.

7. Use of the energy-absorbing and heat-insulating segmented cemented honeycomb material according to any one of claims 1 to 4 in the construction of deep tunnels.

8. Use of the energy-absorbing and heat-insulating segmented bonded honeycomb material according to any one of claims 1 to 4 in the construction of aviation thermal protection systems, earthquake-resistant and energy-saving buildings, or nuclear reactor protection structures.

Images