Experimental material for simulating gradual damage of moraine structure, preparation method and experimental system

Abstract

The invention discloses an experimental material for simulating gradual damage of a moraine structure, a preparation method and an experimental system. The preparation method comprises the following steps: preparing gravels, coarse sand and powder particles into a dry mixture; adding low-temperature molten soda-lime glass powder, and heating to form a siliceous cementation prototype; the preparation method comprises the following steps: adding pretreated calcium type clay and ice crystals into a material in a negative temperature environment, stirring, filling a mold and preliminarily fixing, feeding a carbonate solution into a fixed framework in batches through a liquid supply system at the bottom of the mold to realize mud-salt integrated synergistic cementation, and finally, compacting and carrying out negative temperature maintenance to obtain the experimental material. The experimental system integrates a temperature control unit, a pressurization and force measurement integrated module, an in-mold directional constant-flow liquid supply module and a control unit, and the whole process from material preparation to progressive failure test is integrated and automatically controlled. Compared with the prior art, the method has the advantages that an ice, mud-salt and siliceous triple cementation structure is successfully constructed in the material, and the problem of temperature and pressure disturbance caused by sample transfer is thoroughly solved.

Description

Technical Field

[0001] This invention belongs to the field of geotechnical engineering model testing and geological disaster simulation technology, specifically relating to an experimental material, preparation method and experimental system for simulating the progressive failure of glacial till structures. Background Technology

[0002] Glacial till is a special geological body formed by the accumulation of clastic material carried and transported by glaciers. It is widely distributed in high-altitude areas such as the Qinghai-Tibet Plateau in my country. Its structure is characterized by a typical wide gradation and low roundness, and ice cores are commonly present inside. Glacial till particles typically exhibit various cementation structures, including glacial cementation, mud-salt cementation, and silica cementation. These cementation processes together constitute the complex structural system of glacial till, becoming the core factor controlling its mechanical properties.

[0003] Against the backdrop of global warming, rising temperatures cause the ice cores within glacial till to melt first, triggering a gradual structural failure process characterized by "failure of glacial cementation → weakening of mud-salt cementation → eventual destruction of the siliceous framework." Understanding and revealing the underlying mechanisms of this gradual failure process is crucial for accurate early warning and prevention of major glacial till-related disasters such as glacial lake outburst floods and glacial till landslides.

[0004] Due to the harsh natural environment in areas where glacial till is distributed, in-situ research is extremely difficult, making laboratory research an indispensable tool. However, existing laboratory techniques have significant limitations. First, regarding experimental materials, most current materials used to simulate glacial till focus only on their particle size distribution characteristics (e.g., CN116380725A), neglecting their structural features. In other areas, while some studies focus on the structural features of soil, they only consider one type of cementation characteristic; for example, patent CN116023118A only simulates the siliceous cementation characteristics in red bed soft rock. Existing materials cannot simultaneously reproduce the composite structure of ice, mud-salt integration, and siliceous triple cementation, nor can they simulate the gradual process of the sequential failure of the three types of cementation under heating conditions, leading to significant deviations between model experiments and actual physical processes. Secondly, in terms of experimental systems, existing geotechnical experimental devices are limited in function; conventional presses or temperature control chambers lack the functional modules required for precise, directional, and low-flow liquid supply under negative temperature conditions during the material preparation stage. They also lack the ability to perform programmed heating under continuous constant pressure conditions and simultaneously monitor the entire process of material progressive failure. Material preparation and material testing and analysis are disconnected.

[0005] In summary, the existing technology lacks a material preparation method and testing system capable of simulating the multi-cemented structure of glacial till and fully reproducing its gradual degradation process upon heating. The purpose of this invention is to fill this gap. Summary of the Invention

[0006] Purpose of the invention: This invention discloses an experimental material, preparation method and experimental system for simulating the progressive destruction of glacial till structures. Through a specific process of "stepwise construction and sequential activation", it accurately simulates the formation environment of different cementation processes, avoids mutual interference between processes, and thus stably constructs a multi-cemented structure inside the material.

[0007] Technical solution: This invention discloses an experimental material for simulating the progressive destruction of glacial till structures, comprising a dry mixture, 1.5% to 3.0% of low-temperature molten sodium-calcium glass powder by total mass of the dry mixture, 0.5 to 1.5 parts of calcium-type clay, and 0.5 to 1.0 parts of ice crystals and carbonate solution. The dry mixture comprises 3 to 5 parts of gravel, 3 to 5 parts of coarse sand, and 1 to 2 parts of powder.

[0008] This invention also discloses a method for preparing experimental materials that simulate the progressive destruction of glacial till structures, comprising the following steps:

[0009] Step (1) Batching and pretreatment: Mix 3-5 parts gravel, 3-5 parts coarse sand and 1-2 parts powder by mass, and dry to obtain dry mixture;

[0010] Step (2) Simulation of silica cementation: Add 1.5% to 3.0% of the total mass of the dry mixture to the dry mixture obtained in step (1), mix evenly, heat at high temperature for a certain time and cool to form a silica cementation prototype with initial stability;

[0011] Step (3) Introducing calcium-type clay, pre-embedding ice crystals and fixing the skeleton: In a negative temperature environment, add 0.5 to 1.5 parts of pretreated calcium-type clay and 0.5 to 1.0 parts of ice crystals to the material obtained after cooling in step (2), stir and disperse the mixture; put it into a mold and perform preliminary fixing under a pressure of 0.1 to 0.5 MPa to form a fixed skeleton containing ice crystals;

[0012] Step (4) Mud-salt co-bonding and final molding: Under the condition of maintaining a negative temperature environment, carbonate solution is fed into the fixed skeleton in step (3) from bottom to top in multiple times through the liquid supply system at the bottom of the mold; after the liquid feeding is completed, it is left to stand to achieve mud-salt integrated bonding; then, the final compaction molding is carried out under a pressure of 1 to 2 MPa.

[0013] Step (5) Negative temperature curing: After molding, the specimen is cured at −10℃~0℃ and relative humidity of 10%~20% for 24~48 h before demolding to obtain the experimental material.

[0014] Furthermore, the calcium-type clay is obtained by pretreatment of a mixture of illite and vermiculite in a mass ratio of 9:1. The pretreatment method is as follows: soaking in a calcium chloride solution with a mass concentration of 2% to 4% for 1 to 10 minutes and then draining until it can be formed into a ball by hand without seeping water.

[0015] Furthermore, the calcium chloride solution is a mixture of a saturated calcium hydroxide solution and calcium chloride accounting for 1% to 5% of the mass of calcium hydroxide.

[0016] Furthermore, when feeding the carbonate solution into the fixed skeleton in step (3) multiple times from bottom to top, the flow rate is 0.2 to 0.5 mL / min·kg, and the flow rate is based on the weight of the dry mixture in step (1). The solution is fed into the fixed skeleton in 2 to 3 times, with each feeding lasting 10 to 15 minutes and an interval of 30 to 60 minutes.

[0017] Further, the carbonate solution is a sodium bicarbonate solution with a mass concentration of 0.5% to 1.5% or a sodium carbonate solution with a mass concentration of 0.3% to 1.0%.

[0018] Further, the mass percentage of the low-temperature molten soda-lime glass powder is: SiO2 65-75%, Na2O 12-16%, CaO 6-12%; the median particle size D of the low-temperature molten soda-lime glass powder is... 50 =10~30 μm, low-temperature molten soda-lime glass powder is mixed evenly with dry mixture and then heated at 450~500℃ for 10~60 min.

[0019] Furthermore, in step 4, after the liquid feeding is completed, the mixture is left to stand for 2-4 hours before being compacted and molded.

[0020] Furthermore, the negative temperature environment of the steps and the steps is −5℃~0℃.

[0021] This invention also discloses an experimental system based on the above-mentioned method for preparing experimental materials simulating the progressive destruction of glacial till structures, comprising:

[0022] The sealed chamber contains an experimental room with an insulation layer.

[0023] The temperature control unit is connected to the cooling components and heating elements disposed in the experimental chamber, and is used to provide and maintain a negative temperature environment, and can program the temperature of the experimental chamber to a positive temperature environment at a preset rate R.

[0024] The integrated pressure and force measurement module includes a pressure drive unit, as well as a pressure plate and a force sensor arranged in the experimental chamber and in contact with the sample;

[0025] The data acquisition module is used to acquire axial pressure, axial displacement, and temperature signals, including displacement sensors and temperature sensors;

[0026] The in-mold directional constant flow liquid supply module is arranged at the bottom of the mold or on the inner wall of the mold. It includes a bottom perforated plate or seepage pipe, a liquid inlet, a small flow control unit and an upper overflow or return channel. It is configured to supply carbonate solution to the interior of the sample from bottom to top in a constant small flow rate in stages when the sample is molded and kept under pressure.

[0027] The control unit is connected to the temperature control unit, the integrated pressure and force measurement module, the data acquisition module, and the in-mold directional constant flow liquid supply module via signals.

[0028] Beneficial effects:

[0029] The technical problem this invention aims to solve is to overcome the shortcomings of existing technologies and provide a complete technical solution capable of simulating the multi-cemented structure of glacial till and its progressive failure process under heating conditions with high fidelity. The specific effects are as follows:

[0030] 1. This invention, through a specific, non-obvious "stepwise construction and sequential activation" process, has for the first time stably constructed a triple-cemented structure of ice, mud-salt, and silica that is highly similar to natural glacial till under laboratory conditions. This method ensures the initial formation of the silica framework and the subsequent precise construction of the integrated mud-salt cementation through a unique sequence of first forming a silica framework at high temperature and then introducing ice crystals and active calcium-type clay in a sub-zero environment. The prepared material not only statically simulates its physical and mechanical properties but also accurately reproduces the progressive failure dynamics of the "ice cementation → mud-salt cementation → silica framework" sequence under heating conditions, achieving a high-fidelity simulation of the natural process.

[0031] 2. This invention innovatively integrates an in-mold directional constant flow liquid supply module with a negative temperature environment, pressurization, programmed temperature rise, and data acquisition system, forming a closed-loop controlled experimental platform. This system achieves, for the first time, the entire process from the preparation of structural materials (negative temperature, pressurization, directional liquid supply) to the testing of their progressive failure process (constant pressure programmed temperature rise), completely eliminating temperature fluctuations and structural disturbances caused by sample transfer in traditional methods. This ensures absolute consistency of experimental conditions and extremely high reliability of results, providing an irreplaceable tool for mechanism research.

[0032] 3. This invention solves the technical bottleneck in the simulation of progressive damage of glacial till. All raw materials are readily available and inexpensive. The process flow is clear and controllable, and the system has a high degree of automation, which greatly improves the reliability, repeatability and efficiency of laboratory simulation. It is easy to promote and use in the fields of geotechnical engineering and geological disaster prevention and control research, and has strong theoretical value and engineering practice significance. Attached Figure Description

[0033] Figure 1This invention relates to a method for preparing experimental materials to simulate the progressive destruction of glacial till structures using different material ratios.

[0034] Figure 2 This is a schematic diagram of the experimental system of the present invention;

[0035] Figure 3 This is the axial strain-stress-temperature relationship curve in the verification example of the present invention.

[0036] In the diagram: 1. Sealed chamber; 11. Insulation layer; 12. Experimental chamber; 2. Temperature control unit; 3. Integrated pressurization and force measurement module; 31. Pressure drive unit; 32. Pressure plate; 33. Force sensor; 4. Data acquisition module; 41. Displacement sensor; 42. Temperature sensor; 5. In-mold directional constant flow liquid supply module; 51. Bottom perforated plate or seepage pipe; 52. Liquid inlet interface; 53. Small flow control unit; 54. Upper overflow or return liquid channel; 6. Control unit. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0038] Unless otherwise specified, all embodiments and preferred embodiments mentioned herein can be combined to form new technical solutions.

[0039] In this invention, unless otherwise specified, percentage (%) or number of parts refers to mass percentage or mass parts.

[0040] Example 1

[0041] An experimental material for simulating the progressive destruction of glacial till structures, comprising the following raw materials in parts by mass: 5 parts granite gravel, 3 parts coarse river sand, 1 part powder, 0.5 parts pretreated calcium-type clay, 1.5% low-temperature molten sodium-calcium glass powder (total mass of dry mixture), and 0.5 parts ice crystals.

[0042] The preparation method includes the following steps:

[0043] S1. Batching and Pretreatment: Take granite gravel, coarse river sand, and silt according to the above proportions, mix and dry to obtain a dry mixture. The gravel particle size is 4.75–20 mm with a uniformity coefficient of 3–5; the coarse sand particle size is 2–4.75 mm with a uniformity coefficient of 3–6; and the silt particle size is 0.002–0.075 mm. Mix illite and vermiculite at a mass ratio of 9:1, soak in a 2% calcium chloride solution for 8 minutes, and drain until it can be formed into a ball by hand without water seepage, to obtain pretreated calcium-type clay (calcium-type clay particle size is 0.1–2 μm).

[0044] S2, Simulation of Siliceous Cementation: 1.5% by mass of low-temperature molten soda-lime glass powder (softening point 450~500℃, 600 mesh) was added to the dry mixture obtained in S1. The mass percentage of the low-temperature molten soda-lime glass powder was: SiO2 65~75%, Na2O 12~16%, CaO 6~12%. The median particle size D of the low-temperature molten soda-lime glass powder... 50 =10~30 μm, after being mixed evenly, heat at 500℃ for 30 min, and then cool to form a siliceous cement prototype.

[0045] S3. Ice Crystal Embedding and Skeleton Fixation: In a negative temperature environment of −5℃, 0.5 parts of ice crystals (made from deionized water, irregularly polygonal in shape, with a particle size of 4.75~20mm) and 0.5 parts of pretreated calcium-type clay obtained in S1 are added to the material cooled in S2 and dispersed and mixed. Then, it is loaded into a mold and initially fixed under a pressure of 0.3 MPa to form a fixed skeleton containing ice crystals.

[0046] S4. Mud-Salt Synergistic Bonding and Final Molding: Maintaining a negative temperature environment of −5℃, a 1.0% sodium bicarbonate solution was fed into the fixed skeleton in two batches at a flow rate of 0.3 mL / min·kg through the liquid supply system at the bottom of the mold, each batch lasting 12 min, with an interval of 45 min. After the liquid feeding was completed, the mixture was allowed to stand for 3 h, followed by final compaction molding under a pressure of 1.5 MPa.

[0047] S5. Cure at negative temperature: After curing the molded specimen at −5℃ and 15% relative humidity for 36 h, demold it to obtain the experimental material.

[0048] Example 2

[0049] An experimental material for simulating the progressive destruction of glacial till structures, comprising the following raw materials in parts by mass: 4 parts granite gravel, 4 parts coarse river sand, 1.5 parts powder, 1.0 part pretreated calcium-type clay, 2.5% of the total dry mixture mass of low-temperature molten sodium-calcium glass powder, and 0.8 parts ice crystals.

[0050] The preparation method includes the following steps:

[0051] S1. Batching and Pretreatment: Granite gravel, coarse river sand, and silt were mixed and dried according to the specified ratio to obtain a dry mixture. The gravel had a particle size of 4.75–20 mm and a uniformity coefficient of 3–5; the coarse sand had a particle size of 2–4.75 mm and a uniformity coefficient of 3–6; and the silt had a particle size of 0.002–0.075 mm. Illite and vermiculite were mixed at a mass ratio of 9:1, soaked in a 3% calcium chloride solution for 5 min, and then drained until the mixture could be formed into a ball by hand without water seepage, to obtain pretreated calcium-type clay (the particle size of the calcium-type clay was 0.1–2 μm).

[0052] S2, Simulation of Siliceous Cementation: 2.5% by mass of low-temperature molten soda-lime glass powder (softening point 450~500℃, 600 mesh) was added to the dry mixture obtained in S1. The mass percentage of the low-temperature molten soda-lime glass powder was: SiO2 65~75%, Na2O 12~16%, CaO 6~12%. The median particle size D of the low-temperature molten soda-lime glass powder... 50 =10~30 μm, after being mixed evenly, heat at 450℃ for 45 min, and then cool to form a siliceous cement prototype.

[0053] S3. Ice Crystal Embedding and Skeleton Fixation: In a negative temperature environment of −2℃, 0.8 parts of ice crystals (made from deionized water, particle size 4.75~20mm) and 1.0 part of pretreated calcium-type clay obtained in S1 are added to the material cooled in S2 and dispersed and mixed. Then, it is loaded into a mold and initially fixed under a pressure of 0.2 MPa to form a fixed skeleton containing ice crystals.

[0054] S4. Mud-Salt Synergistic Bonding and Final Molding: Maintaining a negative temperature environment of −2℃, a 0.8% sodium carbonate solution was fed into the fixed skeleton in three portions at a flow rate of 0.4 mL / min·kg through the liquid supply system at the bottom of the mold, each lasting 10 min and spaced 60 min apart. After the liquid feeding was completed, the mixture was allowed to stand for 2.5 h, followed by final compaction molding under a pressure of 1.8 MPa.

[0055] S5. Cure at negative temperature: After curing the molded specimen at −10℃ and 10% relative humidity for 48 h, demold it to obtain the experimental material.

[0056] Example 3

[0057] An experimental material for simulating the progressive destruction of glacial till structures, comprising the following raw materials in parts by mass: 3 parts granite gravel, 5 parts coarse river sand, 2 parts powder, 1.5 parts pretreated calcium-type clay, 3.0% of the total dry mixture mass of low-temperature molten sodium-calcium glass powder, and 1.0 part ice crystals.

[0058] The preparation method includes the following steps:

[0059] S1. Batching and Pretreatment: Granite gravel, coarse river sand, and silt were mixed and dried according to the specified ratio to obtain a dry mixture. The gravel had a particle size of 4.75–20 mm and a uniformity coefficient of 3–5; the coarse sand had a particle size of 2–4.75 mm and a uniformity coefficient of 3–6; and the silt had a particle size of 0.002–0.075 mm. Illite and vermiculite were mixed at a mass ratio of 9:1, soaked in a 4% calcium chloride solution for 2 minutes, and then drained until the mixture could be formed into a ball by hand without water seepage, to obtain pretreated calcium-type clay (the particle size of the calcium-type clay was 0.1–2 μm).

[0060] S2, Simulation of Siliceous Cementation: 3.0% by mass of low-temperature molten soda-lime glass powder (softening point 450~500℃, 600 mesh) was added to the dry mixture obtained in S1. The mass percentage of the low-temperature molten soda-lime glass powder was: SiO2 65~75%, Na2O 12~16%, CaO 6~12%. The median particle size D of the low-temperature molten soda-lime glass powder... 50 =10~30 μm, after being mixed evenly, heat at 480℃ for 60 min, and then cool to form a siliceous cement prototype.

[0061] S3. Ice Crystal Embedding and Skeleton Fixation: In a negative temperature environment of 0℃, 1.0 part of ice crystals (made from deionized water, particle size 4.75~20mm) and 1.5 parts of pretreated calcium-type clay obtained in S1 are added to the material cooled in S2 and dispersed and mixed. Then, it is loaded into a mold and initially fixed under a pressure of 0.5 MPa to form a fixed skeleton containing ice crystals.

[0062] S4. Mud-Salt Synergistic Bonding and Final Molding: Maintaining a negative temperature environment of 0°C, a 1.5% sodium bicarbonate solution was fed into the fixed skeleton twice via the liquid supply system at the bottom of the mold at a flow rate of 0.2 mL / min·kg, each time for 15 min, with a 30 min interval. After the liquid feeding was completed, the mixture was allowed to stand for 4 h, and then final compaction and molding were carried out under a pressure of 2.0 MPa.

[0063] S5. Cure at negative temperature: After curing the molded specimen at −3℃ and 20% relative humidity for 24 h, demold it to obtain the experimental material.

[0064] Comparative Example 1

[0065] The raw material ratio and steps of Example 1 were followed, but in step S2, low-temperature molten sodium-calcium glass powder was not added, nor was heat treatment performed, in order to simulate glacial material without silica cementation.

[0066] Comparative Example 2

[0067] The raw material ratio and steps were carried out according to Example 1, but the clay was not pretreated for calcification in step S1 and the carbonate solution was not fed in step S4 to simulate glacial till material without mud-salt co-bonding.

[0068] Secondly, the physical and mechanical properties of the experimental materials prepared by the above method are shown in the table below.

[0069] Table 1 shows the physical properties of the simulated glacial till structure experimental materials with different material ratios.

[0070] <![CDATA[Density (g / cm 3 )]]> Total moisture content (%) Liquid limit (%) Plastic limit (%) Example 1 1.69 21.91 32.12 18.23 Example 2 1.87 22.62 36.22 19.21 Example 3 1.91 28.52 35.12 23.22 Comparative Example 1 1.40 24.54 34.33 20.21 Comparative Example 2 1.61 30.22 31.51 18.22

[0071] The liquid limit and plastic limit indices in Table 1 were determined using the combined liquid and plastic limit determination method. Three groups of samples were prepared with the same mix ratio, the sinking depth of the cone was measured, the relationship curve between sinking depth and water content was plotted, and the liquid limit and plastic limit values ​​were calculated.

[0072] Table 2 shows the shear properties of the simulated glacial till structure experimental materials with different material ratios.

[0073] Cohesion (kPa) Angle of internal friction (°) Example 1 15.32 30.55 Example 2 19.21 32.65 Example 3 22.53 40.23 Comparative Example 1 9.12 29.12 Comparative Example 2 12.77 34.23

[0074] The cohesion and internal friction angle in the shear parameters of the simulated glacial till structural experimental materials with different material ratios in Table 2 can be determined by direct shear testing. Three specimens were prepared for each embodiment ratio. The specimens were placed in a direct shear testing apparatus, and vertical loads were gradually applied at 100 kPa, 200 kPa, 300 kPa, and 400 kPa, with horizontal shear force applied under each load until shear failure occurred. Shear force and horizontal displacement data were recorded simultaneously with the application of the loads. By plotting shear stress-displacement curves under different vertical loads, the cohesion and internal friction angle were obtained through linear fitting using the Mohr-Coulomb failure criterion.

[0075] Table 3 shows the compressibility properties of the simulated glacial till structure experimental materials with different material ratios.

[0076] <![CDATA[Compressibility factor (MPa -1 ).]]> Elastic modulus (MPa) Uniaxial compressive strength (MPa) Example 1 0.15 185.2 4.51 Example 2 0.22 220.2 6.01 Example 3 0.26 285.5 8.52 Comparative Example 1 0.09 105.2 2.55 Comparative Example 2 0.20 155.9 3.83

[0077] The compressibility, elastic modulus, and uniaxial compressive strength of the simulated glacial till structural test materials with different material ratios in Table 3 can be determined through uniaxial compression and consolidation tests. First, glacial till samples with different ratios are prepared, with three specimens prepared for each ratio. Then, the specimens are subjected to consolidation and uniaxial compression tests respectively. For the consolidation test, different vertical loads are applied, the pressure is gradually increased, and the volume change of the soil sample is measured. The compressibility is calculated by the relationship between load and volume change. For the uniaxial compression test, the specimen is placed in a compression testing machine, a vertical load is applied until the specimen fails, the load and displacement data are recorded, and the elastic modulus is calculated using the stress-strain curve. The uniaxial compressive strength is obtained by applying a gradually increasing axial load until the specimen fails, recording the maximum bearing capacity. The experiment should be repeated three times for each ratio to ensure the accuracy and repeatability of the experimental results.

[0078] Results and Analysis:

[0079] A comparative analysis of the test results in Tables 1, 2, and 3 clearly demonstrates the superior physical and mechanical properties of the material prepared in this invention, as well as the synergistic effect of the multiple bonding system.

[0080] 1. The contribution of multiple bonding systems to material strength and structural integrity

[0081] As can be seen from Comparative Example 1 (without silica cement), its uniaxial compressive strength (2.55 MPa) and elastic modulus (105.2 MPa) are the lowest among all samples. This indicates that silica cement is a key factor in forming the material skeleton and providing final strength. Without silica cement, the material is generally porous, and its load-bearing capacity is significantly reduced.

[0082] As can be seen from Comparative Example 2 (without mud-salt bonding), its uniaxial compressive strength (3.83 MPa) and elastic modulus (155.9 MPa) are higher than those of Comparative Example 1, but significantly lower than those of Example 3 (8.52 MPa, 285.5 MPa) of the complete system. This indicates that mud-salt synergistic bonding, as an important secondary bonding agent, effectively enhances the initial stiffness and integrity of the material, filling the strength gap between the ice crystals and the siliceous framework.

[0083] Comprehensive analysis of Examples 1-3: With the optimized increase of the content of cementing components such as glass powder and calcium-type clay (from Example 1 to Example 3), the density, cohesion, elastic modulus, and uniaxial compressive strength of the materials all showed a systematic improvement. This proves that by controlling the process and proportions described in this invention, the mechanical properties of materials can be precisely designed and enhanced, and a high-strength, natural glacial till structure can be stably constructed.

[0084] 2. The comparison with the comparative examples and embodiments verifies the inventiveness of the invention.

[0085] The materials obtained by this invention (Examples 1-3) exhibit significantly superior key mechanical properties compared to the comparative materials lacking any of the cementing components. This result strongly demonstrates that the "ice-mud-salt-silicon" triple cemented structure formed by the "stepwise construction and sequential activation" process of this invention is an organic whole that supports and synergistically enhances its technical effects far beyond what can be achieved by a single cementation or simple mixing. This non-obvious synergistic effect is precisely the concentrated embodiment of the inventiveness of this invention.

[0086] The above test data and comprehensive analysis fully demonstrate that the experimental material preparation method provided by the present invention can stably reproduce high-fidelity samples with similar structure and mechanical properties to natural glacial till. Furthermore, the dedicated experimental system can effectively reproduce its progressive destruction process, thus fully achieving the intended purpose of the present invention.

[0087] Example 4

[0088] An experimental system for preparing experimental materials that simulate the progressive destruction of glacial till structure includes:

[0089] The sealed chamber 1 has an internal experimental chamber 12 with an insulation layer 11.

[0090] Temperature control unit 2 is connected to the refrigeration component and heating element disposed in the experimental chamber 12, and is used to provide and maintain a negative temperature environment, and can program the temperature of the experimental chamber 12 to a positive temperature environment at a preset rate R.

[0091] The integrated pressure and force measurement module 3 includes a pressure drive unit 31, a pressure plate 32 and a force sensor 33 arranged in the experimental chamber 12 and in contact with the sample.

[0092] The data acquisition module 4 is used to acquire axial pressure, axial displacement and temperature signals, including displacement sensor 41 and temperature sensor 42.

[0093] The in-mold directional constant flow liquid supply module 5 is arranged at the bottom of the mold or on the inner wall of the mold. It includes a bottom perforated plate or seepage pipe 51, a liquid inlet 52, a small flow control unit 53, and an upper overflow or return channel 54. It is configured to supply carbonate solution to the interior of the sample from bottom to top in a constant small flow rate in stages when the sample is molded and kept under pressure.

[0094] Control unit 6 is connected to the temperature control unit 2, the integrated pressurization and force measurement module 3, the data acquisition module 4, and the in-mold directional constant flow liquid supply module 5 via signal connections. It is configured as follows:

[0095] (a) The temperature control unit 2 controls the temperature of the experimental chamber 12 to drop and stabilize at the target curing temperature K1. The target curing temperature K1 satisfies −10℃≤K1≤0℃.

[0096] (b) The pressure P1 is applied and maintained by the integrated pressure and force measurement module 3, and the pressure P1 satisfies 1 MPa ≤ P1 ≤ 2 MPa.

[0097] (c) Control the in-mold directional constant flow liquid supply module 5 to perform liquid supply operation with a specified flow rate, number of times and timing.

[0098] (d) Maintain the conditions of steps (a), (b), and (c) for a first predetermined time, which is 24 to 48 hours.

[0099] (e) Then the temperature control unit 2 is controlled to start the program temperature rise from K1 at the temperature rise rate R. During this process, the pressure and force measurement integrated module 3 is controlled to keep the pressure P1 constant.

[0100] (f) Synchronously record the physical quantities from the data acquisition module 4 and the liquid supply volume and timing from the in-mold directional constant flow liquid supply module 5.

[0101] Verification example:

[0102] To verify the effectiveness of the material and dedicated experimental system of this invention in simulating the progressive destruction process of glacial till, the following experiments were conducted:

[0103] 1. Samples and equipment: Standard samples prepared using the method described in Example 3, and the dedicated experimental system of Example 4 of this invention.

[0104] 2. System Operation and Procedure: Place the sample in the experimental chamber 12 of the system, set the control program through the control unit 6, and execute it automatically:

[0105] (1) Curing stage: The temperature control unit 2 is controlled to reduce the temperature of the experimental chamber to -10℃ and stabilize it at the target curing temperature K1. At the same time, the pressure and force measurement integrated module 3 is controlled to apply and maintain a pressure of 1.8 MPa on the sample for 48 hours (first predetermined time).

[0106] (2) Experimental phase: After curing, the temperature control unit 2 was used to program the temperature of the experimental chamber from −10℃ at a rate (R) of 0.02℃ / minute. During the entire heating process, the pressure and force measurement integrated module 3 was controlled to maintain a constant pressure of 1.8 MPa, and the data acquisition module 4 was started simultaneously to continuously record axial pressure, axial displacement and temperature data at a frequency of once per second.

[0107] 3. Results and Observations: Control unit 6 collects and processes the data, and plots the results as follows: Figure 3The axial strain-stress-temperature curve is shown. Analysis of this curve indicates that the material failure exhibits a clear progressive stage characteristic:

[0108] a) Stage 1 (Ice-cement failure zone, −2 ℃~+2 ℃): The stress-strain curve shows a slight nonlinear upward movement at small strains, with increased strain and a significant decrease in stiffness. This phenomenon is attributed to the loss of ice-cement effect caused by the melting of ice crystals inside the sample. The melting of ice creates micropores and weakens the structure inside the material, causing it to continue to deform without a significant increase in resistance.

[0109] b) Stage Two (Weakening Zone of Mud-Salt Cementation): Within the temperature range of approximately +2℃ to +5℃, the curve gradually transitions from a plateau to a slow rise, which may be accompanied by minor fluctuations (plastic rearrangement / slip). This stage reflects the continued weakening and partial failure of the integrated mud-salt cementation; the overall structure is still hardening, but the upward slope is small and stable. This stage mainly corresponds to the weakening and partial failure of the integrated mud-salt cementation, and is a macroscopic manifestation of the plastic flow and reorganization of the material's internal structure after losing some of the cementation.

[0110] c) Stage Three (Silica-dominated cementation and failure zone): When the temperature exceeds 5°C, the curve steepens rapidly, the stress increases rapidly to the peak value, and then a typical brittle peak appears followed by a rapid decline (softening segment). This segment reflects the dominant load-bearing capacity of the silica skeleton and its brittle fracture.

[0111] 4. Conclusion: This verification example clearly demonstrates the fully automated workflow of the dedicated experimental system of this invention, from sample curing to data acquisition. The obtained experimental data fully proves that the combination of the materials provided by this invention and the experimental system can accurately and repeatedly reproduce and quantify the entire progressive failure process of "ice-like cementation → mud-like cementation → siliceous cementation". This system effectively solves the problems of temperature fluctuations and structural disturbances caused by traditional dispersion equipment during sample transfer, and realizes continuous and accurate observation of the progressive failure process.

[0112] In summary, this invention provides a complete set of experimental materials, their preparation methods, and experimental systems capable of simulating the progressive failure of glacial till structures with high fidelity. The proposed method successfully achieves laboratory reproduction of the multi-cemented structure of natural glacial till and its progressive failure behavior under heating conditions, providing reliable technical support for the study of the mechanisms of related geological hazards.

[0113] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An experimental material simulating progressive failure of a moraine structure, characterized in that, The dry mixture, 1.5-3.0% of low-temperature molten sodium-calcium glass powder of the total mass of the dry mixture, 0.5-1.5 parts of calcium clay, and 0.5-1.0 parts of ice crystals, carbonate solution, the dry mixture comprising 3-5 parts of gravel, 3-5 parts of coarse sand, and 1-2 parts of powder.

2. A method of preparing experimental material simulating progressive failure of a moraine structure, characterized in that, It comprises the following steps: Step (1) batching and pretreatment: 3-5 parts of gravel, 3-5 parts of coarse sand, and 1-2 parts of powder are mixed and dried according to the mass fraction to obtain a dry mixture; Step (2) siliceous cement simulation: 1.5-3.0% of low-temperature molten sodium-calcium glass powder of the total mass of the dry mixture is added to the dry mixture obtained in step (1), and after uniform mixing, it is heated at high temperature for a certain time and cooled to form a siliceous cement prototype with initial stability; Step (3) calcium clay and ice crystal pre-embedding and skeleton fixation: in a negative temperature environment, 0.5-1.5 parts of pretreated calcium clay and 0.5-1.0 parts of ice crystals are added to the material obtained after cooling in step (2), and are mixed by turning and dispersing; load into the mold and perform preliminary fixation under a pressure of 0.1-0.5 MPa to form a fixed skeleton containing ice crystals; Step (4) mud-salt cooperative cementation and final molding: under the condition of maintaining a negative temperature environment, carbonate solution is fed into the fixed skeleton in step (3) from bottom to top in multiple times through the liquid supply system at the bottom of the mold; after the feeding is completed, the mud-salt integration is achieved by standing; then, final compaction molding is performed under a pressure of 1-2 MPa; Step (5) negative temperature curing: after the molded specimen is cured at -10℃-0℃ and a relative humidity of 10%-20% for 24-48 h, it is demolded to obtain the experimental material.

3. A method of preparing experimental material simulating progressive failure of moraine structure according to claim 2, characterized in that, The calcium clay is obtained by pretreating a mixture of illite and vermiculite in a mass ratio of 9:1, and the pretreatment method is: soaking with a 2%-4% calcium chloride solution for 1-10 min and then draining until the mixture does not drip water when held in the hand.

4. The method of claim 3, wherein the method further comprises, The calcium chloride solution is a mixture of saturated calcium hydroxide solution and 1%-5% calcium chloride based on the mass of calcium hydroxide.

5. The method of claim 2, wherein the method further comprises: When feeding the carbonate solution into the fixed skeleton in step (3) from bottom to top in multiple times, the flow rate is 0.2-0.5 mL / min·kg, and the flow rate is 2-3 times based on the weight of the dry mixture in step (1), with each feeding lasting for 10-15 min and the interval being 30-60 min.

6. A method of preparing experimental material simulating progressive failure of moraine structure according to claim 5, characterized in that, The carbonate solution is a 0.5%-1.5% sodium bicarbonate solution or a 0.3%-1.0% sodium carbonate solution.

7. The method of claim 2, wherein the method further comprises: The low-temperature melting sodium-calcium glass powder has a mass ratio of SiO2 65-75 %, Na2O 12-16 %, and CaO 6-12 %; the low-temperature melting sodium-calcium glass powder has a median particle size D 50 =10-30 μm, and the low-temperature melting sodium-calcium glass powder is mixed with the dry mixture uniformly and then heated at 450-500 ℃ for 10-60 min.

8. A method for preparing an experimental material simulating the progressive destruction of glacial till structure according to claim 2 or 5, characterized in that, In step 4, after the feeding is completed, the specimen is allowed to stand for 2-4 h before compaction molding.

9. The method of claim 2, wherein the method further comprises: The negative temperature environment in steps (3) and (4) is -5℃-0℃.

10. An experimental system for preparing an experimental material based on the progressive failure of a simulated moraine structure according to the method of any one of claims 2 to 9, characterized in that, It comprises: A sealed cabin (1) with an experimental chamber (12) having a thermal insulation layer (11) inside; A temperature control unit (2) connected with a refrigeration component and a heating element arranged in the experimental chamber (12) for providing and maintaining a negative temperature environment, and can program the experimental chamber (12) to be warmed to a positive temperature environment at a preset rate R; The pressurization and force measurement integrated module (3) comprises a pressure driving part (31), a pressurization plate (32) arranged in contact with the sample in the experimental chamber (12), and a force sensor (33); The data acquisition module (4) is used for acquiring axial pressure, axial displacement and temperature signals, and comprises a displacement sensor (41) and a temperature sensor (42); The in-mold directional constant-flow liquid supply module (5) is arranged at the bottom of the mold or the inner wall of the mold, comprises a bottom porous plate or a seepage pipeline (51), a liquid inlet interface (52), a small-flow control unit (53) and an upper overflow or liquid return channel (54), and is configured to supply the carbonate solution to the inside of the sample in a constant small flow from bottom to top in batches when the sample is molded and kept in a pressurized state; The control unit (6) is in signal connection with the temperature control unit (2), the pressurization and force measurement integrated module (3), the data acquisition module (4) and the in-mold directional constant-flow liquid supply module (5).

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