A marine soft soil similar material for tunnel instability failure model test and a preparation method thereof

Abstract

The application belongs to the field of underground engineering and relates to a marine soft soil similar material for a tunnel instability and failure model test and a preparation method thereof.The marine soft soil similar material comprises the following components in parts by weight: 95-105 parts of soft clay, 11-30 parts of expansive soil, 8-12 parts of silicone oil and 3-6 parts of washing powder.The application uses common materials in multiple different fields and combines them organically through basic geotechnical experiments: the soft clay determines the permeability of the material, the expansive soil improves the permeability and strength of the material, and the silicone oil improves the cohesion of the material;the permeability and strength of the material are regulated through the expansive soil to meet the experimental requirements and mechanical properties;marine soft soils with different permeabilities are proportioned for model experiments, and a series of reasonable proportions are obtained through a large number of basic experiments, so that the similar material can simulate the site conditions in the tunnel construction process and meet the mechanical and deformation characteristics of the marine soft soil, and the similar material is locally sourced, which is convenient and economical.

Description

Technical Field

[0001] This invention belongs to the field of underground engineering and relates to a marine soft soil similar material for tunnel instability and failure model tests and its preparation method. Background Technology

[0002] With the rapid economic development of the region, the difficulty and requirements of engineering construction are increasing. In recent years, the rapid expansion of urban scale has exacerbated the problem of land scarcity, making the development of urban underground space a hot topic. This has led to a large number of deep foundation pit and tunnel projects being built on marine soft soil foundations. Soft soil is widely distributed in my country and has obvious regional characteristics. Combining the natural geological features and engineering characteristics of soft soil, China's soft soil can be divided into three regions: the northern region, the central region, and the southern region. Marine soft soil in all regions exhibits physical and mechanical properties such as low strength, high water content, and high compressibility, but due to differences in sedimentary history and sedimentary environment, it has obvious regional characteristics. Existing data shows that Shenzhen soft soil is "softer" than Shanghai soft soil, exhibiting a sheet-like structure with a sensitivity coefficient as high as 7-9, indicating strong structural characteristics. Therefore, with the rapid economic development of Shenzhen, a large number of projects need to be built on marine soft soil foundations, making it necessary to conduct in-depth research on the tunnel construction characteristics of soft soil in this region. Among these methods, indoor model test analysis is the most effective research technique for realistically reproducing the engineering construction site. On the one hand, the original soil in the area loses its initial mechanical state due to excavation and transportation, making it unsuitable for testing. On the other hand, civil engineering research often employs model testing methods, which are designed and fabricated according to a specific similarity ratio. Since the original soil cannot meet the similarity ratio requirements, developing similar materials for marine soft soil is crucial for model testing. Therefore, considering the characteristics of marine soft soil in the Shenzhen area, such as high natural water content, large natural void ratio, poor permeability, low strength, high compressibility, and strong structure, it is necessary to develop similar materials for marine soft soil and establish their preparation processes and methods. This will provide important experimental materials and technical support for model testing research on the construction mechanics mechanism of tunnels in marine soft soil strata. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a marine soft soil similar material and its preparation method for tunnel instability and failure model tests. This similar material has properties such as high water content, low strength, and high compressibility, making it easy to simulate the deformation and failure evolution process of marine soft soil induced by tunnel construction. At the same time, it can be sourced locally, improving resource utilization. It is suitable for underground engineering model test research in marine soft soil strata, such as tunnel construction mechanical model tests and deep foundation pit construction mechanical model tests. It can effectively simulate the basic mechanical properties of marine soft soil and provide a guarantee for the accuracy of relevant underground engineering model test results.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] A marine soft soil analog material for tunnel instability failure model tests comprises the following components by weight:

[0006] 95-105 parts soft clay, 11-30 parts expanded clay, 8-12 parts silicone oil, and 3-6 parts laundry detergent.

[0007] Preferably, the laundry detergent is a low-foaming laundry detergent; more preferably, it is Libai low-foaming laundry detergent or Super Low-Foaming Laundry Detergent.

[0008] Preferably, the standard kinematic viscosity of the silicone oil is 500 ps.

[0009] Preferably, a marine soft soil similar material for tunnel instability failure model tests comprises the following components by weight:

[0010] High-permeability marine soft soil: 96-105 parts soft clay, 11-17 parts expansive soil, 8-10 parts silicone oil, and 3-6 parts laundry detergent.

[0011] Alternatively, for medium-permeability marine soft soil: 95-104 parts soft clay, 17-25 parts expansive soil, 8-11 parts silicone oil, and 3-6 parts laundry detergent.

[0012] Alternatively, low-permeability marine soft soil: 96-105 parts soft clay, 25-30 parts expansive soil, 9-12 parts silicone oil, and 3-6 parts laundry detergent.

[0013] The permeability coefficient of the highly permeable marine soft soil is 2.7 × 10⁻⁶. -6 ≤Permeability coefficient<3.4×10 -6 The permeability coefficient of the moderately permeable marine soft soil is 1.8 × 10⁻⁶. -6 ≤Permeability coefficient<2.7×10 -6 The permeability coefficient of the low-permeability marine soft soil is 1.0 × 10⁻⁶. -6 ≤Permeability coefficient<1.8×10 -6 .

[0014] A further preferred embodiment of a marine soft soil similar material for tunnel instability and failure model tests comprises the following components by weight:

[0015] Highly permeable marine soft soil: 100 parts soft clay, 11-13 parts expansive soil, 8-9 parts silicone oil, and 3-6 parts laundry detergent;

[0016] Alternatively, for medium-permeability marine soft soil: 100 parts soft clay, 17-19 parts expansive soil, 8-10 parts silicone oil, and 3-6 parts laundry detergent.

[0017] Alternatively, low-permeability marine soft soil: 100 parts soft clay, 25-27 parts expansive soil, 9-11 parts silicone oil, and 3-6 parts laundry detergent.

[0018] A further preferred embodiment of a marine soft soil similar material for tunnel instability and failure model tests comprises the following components by weight:

[0019] Highly permeable marine soft soil: 100 parts soft clay, 12 parts expansive soil, 9 parts silicone oil, and 4 parts laundry detergent.

[0020] Alternatively, medium-permeability marine soft soil: 100 parts soft clay, 18 parts expansive soil, 10 parts silicone oil, and 5 parts laundry detergent.

[0021] Alternatively, low-permeability marine soft soil: 100 parts soft clay, 25 parts expansive soil, 11 parts silicone oil, and 6 parts laundry detergent.

[0022] The preferred embodiment is that the soft clay is taken from the Quaternary Holocene marine sedimentary layer in the Shenzhen area.

[0023] The method for preparing marine soft soil similar materials for tunnel instability and failure model tests includes the following steps:

[0024] (1) Mix soft clay and expansive soil evenly, then add silicone oil and laundry detergent, mix evenly to obtain a mixed material;

[0025] (2) Compact the mixed material described in step (1) into a mold.

[0026] The purpose of adding silicone oil and laundry detergent to the mixed material is to simulate the cohesion of actual geological rock and soil materials. The amount of silicone oil used should not be too large. If the amount of silicone oil is too large, it will significantly reduce the permeability of the material, thus leading to the failure of the experiment. If the amount of silicone oil is too small, it may lead to insufficient cohesion of similar materials, and thus premature destruction of the strata during the simulated excavation process.

[0027] Preferably, the soft clay in step (1) is sieved through a 0.5mm sieve; the expansive soil in step (1) is sieved through a 0.5mm sieve.

[0028] Preferably, the compaction degree of the compaction molding in step (2) is in the range of 90-95%.

[0029] The application of the marine soft soil similar material in tunnel construction mechanical model tests is used to simulate the marine soft soil in the Shenzhen area for tunnel construction mechanical model tests.

[0030] The beneficial effects of this invention are:

[0031] 1. In order to achieve the desired properties of similar materials, this invention uses several commonly used materials from different fields and combines them organically through basic geotechnical experiments: soft clay determines the material's permeability, expansive soil improves the material's permeability and strength, and silicone oil enhances the material's cohesion, which can provide some reference for similar application inventions.

[0032] 2. The similar materials in this invention can be adjusted and controlled by expansive soil to meet experimental requirements and mechanical properties.

[0033] 3. This invention can be used to conduct model experiments with marine soft soils of different permeability. Through a large number of basic experiments, a series of reasonable proportions have been obtained, so that similar materials can not only simulate the on-site conditions of tunnel construction, but also meet the mechanical and deformation characteristics of marine soft soils. It is convenient and economical to use local materials. Detailed Implementation

[0034] The present invention will be further described below with reference to specific embodiments, and the advantages and features of the present invention will become clearer with the description. However, the embodiments are merely exemplary and do not constitute any limitation on the scope of the present invention. Those skilled in the art should understand that modifications or substitutions can be made to the details and form of the technical solutions of the present invention without departing from the spirit and scope of the present invention, but all such modifications and substitutions fall within the protection scope of the present invention.

[0035] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0036] The standard kinematic viscosity of the silicone oil described in the specific embodiment is 500 ps. The laundry detergent used is a super-low-foaming laundry detergent.

[0037] The soft clay was taken from the Quaternary Holocene marine sedimentary layer in the Shenzhen area.

[0038] The geological conditions within the construction area of ​​the tunnel project between Hai Shang Tian Yuan East and Hai Shang Tian Yuan South sections of Shenzhen Metro Line 12, from top to bottom, are as follows: plain fill, silt, marine soft soil, pebbles, completely weathered granite, strongly weathered granite, and moderately weathered granite. The main tunnel structure is primarily located within the marine soft soil. The engineering mechanical properties of the marine soft soil in this area are: water content 64.2%, void ratio 1.816, and permeability coefficient 2.25 × 10⁻⁶. -6 Shear strength 10.2 kPa, compression modulus 5.97 MPa.

[0039] A model experiment simulating the mechanical mechanism of tunnel construction in marine soft soil strata was conducted. The similarity ratio of the model experiment was 1:50. Based on experimental requirements, multiple groups of similar materials with different permeability coefficients and strengths were selected for comparative research.

[0040] Example 1

[0041] A marine soft soil similar material for tunnel instability and failure model testing is prepared using the following steps:

[0042] (1) Select soft clay and expansive soil without obvious impurities, and determine that the permeability of the similar material required for the model test is high-permeability marine soft soil. Mix them according to the following weight ratio: 100 parts soft clay and 11 parts expansive soil. The soft clay is sieved through a 0.5 mm sieve, and the expansive soil is sieved through a 0.5 mm sieve. Add the materials and stir to make the materials evenly mixed. Add silicone oil and laundry detergent to the evenly mixed materials. The mass of silicone oil is 9% of the sum of the masses of soft clay and expansive soil, and the mass of laundry detergent is 50% of the mass of silicone oil.

[0043] (2) The compaction degree was controlled according to experimental requirements to compact the model test material into shape. Under a compaction degree of 95%, the water content of the obtained marine soft soil-like material was 68.7%, the void ratio was 1.924, and the permeability coefficient was 3.2 × 10⁻⁶. -6 The material has a strength of 0.52 kPa and a compressive modulus of 0.63 MPa. Based on the similarity ratio coefficient, determine the required similar material.

[0044] Example 2

[0045] A marine soft soil similar material for tunnel instability and failure model testing is prepared using the following steps:

[0046] (1) Select soft clay and expansive soil without obvious impurities. Determine that the permeability of the similar material required for the model test is medium-permeability marine soft soil. Mix 100 parts soft clay and 17 parts expansive soil by weight. The soft clay is sieved through a 0.5 mm sieve and the expansive soil is sieved through a 0.5 mm sieve. Add the materials and stir to make the materials evenly mixed. Add silicone oil and laundry detergent to the evenly mixed materials. The mass of silicone oil is 8% of the sum of the masses of soft clay and expansive soil, and the mass of laundry detergent is 50% of the mass of silicone oil.

[0047] (2) The compaction degree was controlled according to experimental requirements to compact the model test material into shape. Under a compaction degree of 95%, the water content of the obtained marine soft soil-like material was 62.5%, the void ratio was 1.638, and the permeability coefficient was 2.6 × 10⁻⁶. -6 cm / s, shear strength 0.84kPa, compression modulus 0.92MPa.

[0048] Example 3

[0049] A marine soft soil similar material for tunnel instability and failure model testing is prepared using the following steps:

[0050] (1) Select soft clay and expansive soil without obvious impurities. Determine that the permeability of the similar material required for the model test is low-permeability marine soft soil. Mix 100 parts of soft clay and 25 parts of expansive soil by weight. The soft clay is sieved through a 0.5 mm sieve and the expansive soil is sieved through a 0.5 mm sieve. Add the materials and stir to make the materials evenly mixed. Add silicone oil and laundry detergent to the evenly mixed materials. The mass of silicone oil is 9% of the sum of the masses of soft clay and expansive soil, and the mass of laundry detergent is 50% of the mass of silicone oil.

[0051] (2) The compaction degree was controlled according to experimental requirements to compact the model test material into shape. Under a compaction degree of 95%, the water content of the obtained marine soft soil-like material was 58.6%, the void ratio was 1.486, and the permeability coefficient was 1.7×10⁻⁶. -6 cm / s, shear strength 1.12kPa, compression modulus 1.47MPa.

[0052] Example 4

[0053] A marine soft soil similar material for tunnel instability and failure model testing is prepared using the following steps:

[0054] (1) Select soft clay and expansive soil without obvious impurities. Determine that the permeability of the similar material required for the model test is high-permeability marine soft soil. Mix 100 parts soft clay and 12 parts expansive soil by weight. The soft clay is sieved through a 0.5 mm sieve and the expansive soil is sieved through a 0.5 mm sieve. Add the materials and stir to make the materials evenly mixed. Add silicone oil and laundry detergent to the evenly mixed materials. The mass of silicone oil is 9 parts and the mass of laundry detergent is 4 parts.

[0055] (2) The compaction degree was controlled according to experimental requirements to compact the model test material into shape. Under a compaction degree of 95%, the water content of the obtained marine soft soil-like material was 67.9%, the void ratio was 1.916, and the permeability coefficient was 3.1×10⁻⁶. -6 cm / s, shear strength 0.51kPa, compression modulus 0.62MPa.

[0056] Example 5

[0057] A marine soft soil similar material for tunnel instability and failure model testing is prepared using the following steps:

[0058] (1) Select soft clay and expansive soil without obvious impurities. Determine that the permeability of the similar material required for the model test is medium-permeability marine soft soil. Mix 100 parts soft clay and 18 parts expansive soil by weight. The soft clay is sieved through a 0.5 mm sieve and the expansive soil is sieved through a 0.5 mm sieve. Add the materials and stir to make the materials evenly mixed. Add silicone oil and laundry detergent to the evenly mixed materials. The mass of silicone oil is 10 parts and the mass of laundry detergent is 5 parts.

[0059] (2) The compaction degree was controlled according to experimental requirements to compact the model test material into shape. Under a compaction degree of 95%, the water content of the obtained marine soft soil-like material was 61.8%, the void ratio was 1.586, and the permeability coefficient was 2.5 × 10⁻⁶. -6 cm / s, shear strength 0.82kPa, compression modulus 0.90MPa.

[0060] Example 6

[0061] A marine soft soil similar material for tunnel instability and failure model testing is prepared using the following steps:

[0062] (1) Select soft clay and expansive soil without obvious impurities. Determine that the permeability of the similar material required for the model test is high-permeability marine soft soil. Mix 100 parts soft clay and 25 parts expansive soil by weight. Use a 0.5 mm sieve for soft clay and a 0.5 mm sieve for expansive soil. Add the materials and stir to make the materials evenly mixed. Add silicone oil and laundry detergent to the evenly mixed materials. The mass of silicone oil is 11 parts and the mass of laundry detergent is 6 parts.

[0063] (2) The compaction degree was controlled according to experimental requirements to compact the model test material into shape. Under 95% compaction degree, the water content of the obtained marine soft soil-like material was 57.8%, the void ratio was 1.464, and the permeability coefficient was 1.6×10⁻⁶. -6 cm / s, shear strength 1.10 kPa, compression modulus 1.42 MPa.

[0064] The comparative analysis of the above examples shows that the similar material proposed in this patent, tailored to the characteristics of marine soft soil in Shenzhen, can be used in model tests simulating actual engineering projects and meets various index requirements.

[0065] Comparative Example 1

[0066] A marine soft soil similar material for tunnel instability and failure model testing is prepared using the following steps:

[0067] (1) Select soft clay and expansive soil without obvious impurities, and determine that the permeability of the similar material required for the model test is high-permeability marine soft soil. Mix them according to the following weight ratio: 100 parts soft clay and 11 parts expansive soil. The soft clay is sieved through a 0.5 mm sieve, and the expansive soil is sieved through a 0.5 mm sieve. Add the materials and stir to make the materials evenly mixed. Add silicone oil and laundry detergent to the evenly mixed materials. The mass of silicone oil is 12% of the sum of the masses of soft clay and expansive soil, and the mass of laundry detergent is 50% of the mass of silicone oil.

[0068] (2) The compaction degree was controlled according to experimental requirements to compact the model test material into shape. Under 95% compaction degree, the water content of the obtained marine soft soil-like material was 56.4%, the void ratio was 1.469, and the permeability coefficient was 1.42×10⁻⁶. -6 The material has a strength of 0.75 kPa and a compressive modulus of 0.87 MPa. Based on the similarity ratio coefficient, determine the required similar material.

[0069] As can be seen from Comparative Example 1, compared with Example 1, the excessive amount of silicone oil leads to increased viscosity of similar materials, enhanced adhesion between soil particles, and decreased permeability coefficient.

[0070] Comparative Example 2

[0071] A marine soft soil similar material for tunnel instability and failure model testing is prepared using the following steps:

[0072] (1) Select soft clay and expansive soil without obvious impurities, and determine that the permeability of the similar material required for the model test is high-permeability marine soft soil. Mix them according to the following weight ratio: 100 parts soft clay and 11 parts expansive soil. The soft clay is sieved through a 0.5 mm sieve, and the expansive soil is sieved through a 0.5 mm sieve. Add the materials and stir to make the materials evenly mixed. Add silicone oil and laundry detergent to the evenly mixed materials. The mass of silicone oil is 5% of the sum of the masses of soft clay and expansive soil, and the mass of laundry detergent is 50% of the mass of silicone oil.

[0073] (2) The compaction degree was controlled according to experimental requirements to compact the model test material into shape. Under a compaction degree of 95%, the water content of the obtained marine soft soil-like material was 70.4%, the void ratio was 1.954, and the permeability coefficient was 3.41×10⁻⁶. -6 The material has a strength of 0.43 kPa and a compressive modulus of 0.54 MPa. Based on the similarity ratio coefficient, determine the required similar material.

[0074] As can be seen from Comparative Example 2, compared with Example 1, the low amount of silicone oil resulted in a decrease in the viscosity of the similar materials, looser particles, and an increase in the permeability coefficient.

[0075] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A marine soft soil similar material for tunnel instability and failure model tests, characterized in that, It includes the following components by weight: 95-105 parts soft clay, 11-30 parts expanded clay, 8-12 parts silicone oil, and 3-6 parts laundry detergent; the standard kinematic viscosity of the silicone oil is 500 ps; the laundry detergent is a low-foaming laundry detergent.

2. The marine soft soil similar material for tunnel instability and failure model testing according to claim 1, characterized in that, Includes the following components by weight: Highly permeable marine soft soil: 100 parts soft clay, 11-13 parts expansive soil, 8-9 parts silicone oil, and 3-6 parts laundry detergent; Alternatively, for medium-permeability marine soft soil: 100 parts soft clay, 17-19 parts expansive soil, 8-10 parts silicone oil, and 3-6 parts laundry detergent; Alternatively, low-permeability marine soft soil: 100 parts soft clay, 25-27 parts expansive soil, 9-11 parts silicone oil, and 3-6 parts laundry detergent; The permeability coefficient of the highly permeable marine soft soil is 2.7 × 10⁻⁶. -6 ≤Permeability coefficient<3.4×10 -6 The permeability coefficient of the moderately permeable marine soft soil is 1.8 × 10⁻⁶. -6 ≤Permeability coefficient<2.7×10 -6 The permeability coefficient of the low-permeability marine soft soil is 1.0 × 10⁻⁶. -6 ≤Permeability coefficient<1.8×10 -6 .

3. The marine soft soil similar material for tunnel instability and failure model testing according to claim 1, characterized in that, Includes the following components by weight: Highly permeable marine soft soil: 100 parts soft clay, 12 parts expansive soil, 9 parts silicone oil, and 4 parts laundry detergent. Alternatively, medium-permeability marine soft soil: 100 parts soft clay, 18 parts expansive soil, 10 parts silicone oil, and 5 parts laundry detergent. Alternatively, low-permeability marine soft soil: 100 parts soft clay, 25 parts expansive soil, 11 parts silicone oil, and 6 parts laundry detergent.

4. A marine soft soil similar material for tunnel instability and failure model tests according to any one of claims 1-3, characterized in that, The soft clay was taken from the Quaternary Holocene marine sedimentary layer in the Shenzhen area.

5. The method for preparing marine soft soil similar materials for tunnel instability and failure model tests according to claim 4, characterized in that, Includes the following steps: (1) Mix soft clay and expansive soil evenly, then add silicone oil and laundry detergent, mix evenly to obtain a mixed material; (2) Compact the mixed material described in step (1) into shape.

6. The method for preparing marine soft soil similar materials for tunnel instability and failure model tests according to claim 5, characterized in that, The soft clay in step (1) is sieved through a 0.5mm sieve; the expansive soil in step (1) is sieved through a 0.5mm sieve; preferably, the compaction degree of the compaction molding in step (2) is in the range of 90-95%.

7. The application of the marine soft soil similar material according to claim 6 for tunnel instability and failure model tests, characterized in that, The marine soft soil similar material was used to simulate the marine soft soil in the Shenzhen area for tunnel construction mechanical model tests.