Preparation method and application of modified shield soil recycled coarse aggregate

Abstract

The invention belongs to the technical field of modified shield soil recycled coarse aggregates, and particularly relates to a preparation method and application of a modified shield soil recycled coarse aggregate, and the preparation method comprises the following steps: 1) preparing a modification liquid from poly (dimethyl siloxane), bis (3-aminopropyl) terminated, linear novolac epoxy resin, a nano filler and an organic solvent; and 2) dipping the shield soil recycled coarse aggregate in the modification liquid, stirring under an ultrasonic condition, taking out, and drying to obtain the modified shield soil recycled coarse aggregate. The poly (dimethyl siloxane), the bis (3-aminopropyl) end cap, the linear novolac epoxy resin and the nano-filler fully permeate into pores and gaps of the shield soil recycled coarse aggregate, and the nano-filler physically blocks the internal pores, repairs micro-cracks and reduces the water absorption rate; the siloxane chain segment of the amino-terminated silicon oil directionally forms a hydrophobic membrane, and the amino-terminated group and the linear novolac epoxy resin are cross-linked and cured to block moisture invasion; and the linear novolac epoxy resin firmly bonds the fragile part, so that the mechanical property and durability are improved.

Description

Technical Field

[0001] This invention belongs to the technical field of modified shield tunnel soil recycled coarse aggregate, specifically relating to a method for preparing modified shield tunnel soil recycled coarse aggregate and its application. Background Technology

[0002] Due to its advantages of high precision, low environmental disturbance, and efficient construction, the shield tunneling method has become the core construction method for modern tunnel engineering (such as traffic tunnels and water conservancy tunnels). With the rapid development of my country's economy, the amount of tunnel boring machine (TBM) soil generated during TBM construction is enormous. Due to inconvenient transportation or high transportation costs, the soil is often disposed of by on-site stockpiling or backfilling. However, TBM soil contains resources such as sand, gravel, and clay that can be utilized. Direct stockpiling or backfilling not only wastes resources but also occupies land and damages surface vegetation and soil erosion.

[0003] After sorting, washing and other processes, the soil from shield tunneling machines produces soil, gravel or mixed gravel of various particle sizes. It has great resource utilization value in the fields of roadbed filling, building material aggregate, slope protection and other fields. Researchers in this field have conducted a lot of research on the resource reuse of shield tunneling soil, such as a method for the resource utilization of all particle sizes of slurry shield tunneling excavated soil disclosed in patent CN117920732B, and a process for preparing flowing backfill material based on shield tunneling waste slurry disclosed in patent CN116023080B.

[0004] The above are technologies for the resource recycling of shield tunnel soil, but they focus more on full-size sorting or the utilization of fine-grained components, and do not study the compatibility of the generated aggregate with its actual application. Although the aggregate can play a basic role in bearing load and providing structural strength, its performance may be constrained by the characteristics of the original strata, and there are still defects in some applications. In particular, the performance defects of recycled coarse aggregate from shield tunnel soil produced by strata with high clay content (such as claystone, silty mudstone, and completely weathered granite strata) are the most prominent.

[0005] During the diagenesis of strata with high clay content, the sedimentary environment and cementation processes often result in the inclusion of clay minerals such as kaolinite and illite in varying proportions. These clay minerals are embedded in the original rock framework in the form of layered fillings or cemented encapsulations, resulting in residual clay mineral components in the recycled aggregate prepared from shield tunneling soil from such strata, both on the surface and inside. Even the clay minerals that filled the pores in the original rock will still adhere to the internal pores and secondary fractures of the recycled aggregate after the rock is broken. Furthermore, under the intense cutting action of the tunnel boring machine, the original rock rich in clay minerals has a complex internal stress distribution, unlike hard rocks such as quartzite which mainly form primary fractures due to external crushing forces. This type of aggregate will continue to experience secondary fracture expansion. The aforementioned diagenetic and crushing mechanisms together lead to a significantly higher water absorption rate and crushing value in the recycled aggregate from shield tunneling soil.

[0006] Because roadbeds are not only directly exposed to the natural environment and subjected to extreme climates and dynamic loads, but also need to maintain structural stability over a long period of time to ensure traffic safety, the environmental harshness and performance requirements they face are far higher than those of ordinary backfill materials. When recycled aggregates prepared from shield soil produced by strata with high clay content are applied to roadbed materials, in freeze-thaw environments, the pore water inside these aggregates freezes and expands, generating internal stress, causing the aggregates to break and significantly reducing the strength and durability of the roadbed structure, which becomes a key obstacle restricting its large-scale application.

[0007] Therefore, it is necessary to modify this recycled coarse aggregate from shield tunneling soil so that it can be used on a large scale in roadbed materials. Summary of the Invention

[0008] To address the aforementioned technical problems, this invention provides a method for preparing and applying modified shield tunnel soil recycled coarse aggregate. A modifying solution was prepared using poly(dimethylsiloxane), bis(3-aminopropyl) end-capped material, linear phenolic epoxy resin, nanofillers, and organic solvents. This solution was then used to impregnate recycled shield tunneling soil coarse aggregate to obtain modified recycled shield tunneling soil coarse aggregate. The poly(dimethylsiloxane), bis(3-aminopropyl) end-capped material, linear phenolic epoxy resin, and nanofillers in the modifying solution fully penetrated the pores and fissures of the recycled shield tunneling soil coarse aggregate. The nanofillers physically blocked internal pores, repaired microcracks, and blocked water penetration paths to reduce water absorption. The siloxane segments of the amino-terminated silicone oil formed a hydrophobic film, and its amino-terminated segments cross-linked and cured with the linear phenolic epoxy resin, filling pores and fixing the hydrophobic structure to prevent water intrusion. During the drying process, the linear phenolic epoxy resin firmly bonded the fragile parts, thereby enhancing the overall integrity of the aggregate, improving its mechanical properties, and reducing its water absorption value, ultimately improving the mechanical properties and durability of the roadbed material.

[0009] To achieve the above objectives, the following technical solution is adopted: A method for preparing modified shield tunnel soil recycled coarse aggregate includes the following steps: 1) A modified solution was prepared using poly(dimethylsiloxane), bis(3-aminopropyl) end-capped, linear phenolic epoxy resin, nanofiller, and organic solvent; 2) The recycled coarse aggregate of the shield tunnel soil is immersed in the modification liquid, stirred under ultrasonic conditions, removed and dried to obtain modified recycled coarse aggregate of the shield tunnel soil.

[0010] In step 1), the mass ratio of poly(dimethylsiloxane), bis(3-aminopropyl)-terminated, linear phenolic epoxy resin, and nanofiller is 1-3:5-8:3-5.

[0011] In step 1), the poly(dimethylsiloxane) with bis(3-aminopropyl) end caps has a number-average molecular weight of 1000-3000 g / mol. The linear phenolic epoxy resin has an epoxy value of 0.46-0.60. The nanofiller has an average particle size of 30-100 nm. The nanofiller is selected from one or more combinations of nano-silica, nano-titanium dioxide, nano-calcium carbonate, nano-silicon nitride, and nano-alumina. The organic solvent is selected from one or more combinations of ethanol, propanol, isopropanol, tetrahydrofuran, and propyl acetate. The organic solvent makes the modified liquid-solid content 15-25 wt%.

[0012] In step 2), the mass-to-volume ratio of the recycled shield tunneling soil coarse aggregate to the modified liquid is 1 kg: 10-20 L. The impregnation temperature is 0-30℃. The ultrasonic power is 300-500 W, and the stirring is performed at a speed of 200-300 r / min for 15-30 min. The drying is carried out at 100-120℃ for 1-3 h, and the organic solvent is recovered.

[0013] In step 2), the recycled coarse aggregate of the shield tunnel soil has a particle size of 5-20mm, a water absorption rate of 10-15%, a crushing value of 30-40%, a mud content of 3-6%, and a moisture content of ≤1.6wt%.

[0014] In step 2), the recycled coarse aggregate of the shield tunnel soil is obtained by a method including the following steps: pre-crushing, ball milling, crushing, washing, dewatering, drying and screening of the shield tunnel soil to obtain the recycled coarse aggregate of the shield tunnel soil.

[0015] Furthermore, the moisture content of the shield soil is 20-60%, and the apparent density is 1400-1800 kg / m³. 3 Plastic limit 12-30%, liquid limit 25-70%, pH value 6-8, organic matter content ≤5%.

[0016] Further, the pre-crushing involves crushing the shield soil to a particle size ≤45mm using a jaw crusher. The ball milling involves grinding the pre-crushed shield soil to a particle size ≤40mm using a planetary ball mill, and then screening out shield soil with a particle size of 20-40mm. The crushing involves crushing the 20-40mm shield soil to a particle size ≤20mm using an impact crusher. The washing involves washing the sand with a spiral sand washer at a speed of 10-20 r / min for 1-5 minutes. The dewatering involves dewatering with a belt filter press to achieve a moisture content of 15-20wt% for the shield soil with a particle size ≤20mm. The drying involves drying at 60-100℃ to a moisture content ≤1.6wt%. The screening process separates recycled shield soil coarse aggregate with a particle size of 5-20mm.

[0017] A roadbed material comprising the following raw materials in parts by weight: 80-100 parts of modified shield soil recycled coarse aggregate prepared by the above-mentioned method, 15-20 parts of blast furnace slag, 10-15 parts of fly ash, 0.5-1 parts of polycarboxylate superplasticizer, 1-2 parts of alkali activator, 0.3-0.5 parts of polymer fiber, 0.1-0.5 parts of air-entraining agent, and 50-70 parts of water.

[0018] The blast furnace slag has an activity index ≥95% and a specific surface area ≥450 m² after 28 days. 2 / kg.

[0019] The fly ash is either Grade I fly ash or Grade II fly ash.

[0020] The water reduction rate of the polycarboxylate superplasticizer is 15-35%.

[0021] The alkaline activator is selected from one or more of calcium hydroxide, sodium silicate, sodium bicarbonate, sodium silicate, and potassium silicate.

[0022] The polymer fiber is selected from one or a combination of two of PVC fiber and PP fiber.

[0023] The polymer fibers are 8-12 mm long and 10-30 μm in diameter.

[0024] The air-entraining agent is an anionic surfactant selected from one or a combination of two of sodium dodecylbenzene sulfonate, sodium stearate, sodium α-olefin sulfonate, and sodium dodecyl alcohol sulfate.

[0025] The present invention also provides a method for preparing the above-mentioned roadbed material, comprising the following steps: The modified shield soil recycled coarse aggregate prepared by the modified shield soil recycled coarse aggregate preparation method, blast furnace slag, fly ash, and polymer fiber are mixed with water to obtain mixture A. Polycarboxylate superplasticizer, alkali activator, and air-entraining agent are mixed to obtain mixture B. A and B are stirred evenly to obtain shield soil subgrade material.

[0026] Compared with the prior art, the beneficial effects of the present invention are: This invention uses poly(dimethylsiloxane), bis(3-aminopropyl) end-capped polymer, linear phenolic epoxy resin, nanofillers, and organic solvents to prepare a modifying liquid. Shield tunnel soil recycled coarse aggregate is impregnated in this liquid to obtain modified shield tunnel soil recycled coarse aggregate. The poly(dimethylsiloxane), bis(3-aminopropyl) end-capped polymer, linear phenolic epoxy resin, and nanofillers in the modifying liquid fully penetrate the pores and gaps of the shield tunnel soil recycled coarse aggregate. The nanofillers physically block internal pores, repair microcracks, and block water penetration paths to reduce water absorption. The siloxane segments of the amino-terminated silicone oil directionally form a hydrophobic film, and its amino-terminated polymer cross-links and cures with the linear phenolic epoxy resin, filling pores and fixing the hydrophobic structure to prevent water intrusion. During the drying process, the linear phenolic epoxy resin firmly bonds the fragile parts, thereby enhancing the integrity of the aggregate, improving mechanical properties, and reducing water absorption, thus improving the mechanical properties and durability of the roadbed material. Detailed Implementation

[0027] The present invention will be further described below with reference to specific embodiments, but is not limited to the contents of the specification. Unless otherwise specified, all "parts" mentioned in the embodiments of the present invention are parts by weight. All reagents used are commercially available in the art.

[0028] Poly(dimethylsiloxane), bis(3-aminopropyl)-terminated D030174, number average molecular weight 1000 g / mol, from Anage.

[0029] Poly(dimethylsiloxane), bis(3-aminopropyl)-terminated D030172, with a number-average molecular weight of 3000 g / mol, is from Anage.

[0030] The linear phenolic epoxy resin EPN1179, from Shanghai Kaiyin Chemical Co., Ltd., has an epoxy value of 0.56.

[0031] The linear phenolic epoxy resin BNE200, sourced from Nanjing Kexucai Chemical Co., Ltd., has an epoxy value of 0.48.

[0032] The nano-silica DK-SiO2-30, with an average particle size of 30nm, comes from Zhongke Leiming (Beijing) Technology Co., Ltd.

[0033] The nano-silica VK-SP100F, with an average particle size of 100nm, comes from Xuancheng Jingrui New Materials Co., Ltd.

[0034] The PVC fiber is 12mm long and 30μm in diameter, and comes from Shandong Hongju Engineering Materials Co., Ltd.

[0035] Blast furnace slag 28 days old has an activity index of 95% and a specific surface area of ​​550 m². 2 / kg, from Hebei Wenfeng Industrial Group Co., Ltd.

[0036] The polycarboxylate superplasticizer TR-26C has a water reduction rate of 20% and is sourced from Luoyang Tongrun Information Technology Co., Ltd.

[0037] The soil used for the tunnel boring machine (TBM) came from the Hengqinzhou Tunnel in Zhuhai, Guangdong. The basic physical and chemical properties of the TBM soil are shown in Table 1. Table 1 Basic physical and chemical properties of soil used in shield tunneling .

[0038] Example 1 1) Mix 30 parts by weight of poly(dimethylsiloxane), bis(3-aminopropyl)-terminated D030172, 80 parts by weight of linear phenolic epoxy resin EPN1179, 50 parts by weight of nano silica DK-SiO2-30 with the organic solvent tetrahydrofuran to prepare a modified solution with a solid content of 25%. 2) The shield soil in Table 1 is first pre-crushed to a particle size of ≤45mm using a jaw crusher, then ball-milled to a particle size of ≤40mm using a planetary ball mill, and the shield soil with a particle size of 20-40mm is screened out. Then, the shield soil with a particle size of 20-40mm is crushed to a particle size of ≤20mm using an impact crusher, and then washed with a spiral sand washer at a speed of 15r / min for 3min. Then, it is dewatered using a belt filter press to make the shield soil with a particle size of ≤20mm have a moisture content of 15wt%. Finally, it is dried at 100℃ to a moisture content of 1wt%, and screened to obtain recycled coarse aggregate of shield soil with a particle size of 5-20mm, a water absorption rate of 15%, a crushing value of 40%, a mud content of 6%, and a moisture content of 1wt%. The recycled coarse aggregate of the shield tunnel soil was immersed in the modification liquid at a mass-volume ratio of 1kg:20L at 25℃. Under ultrasonic conditions of 300W power, it was stirred at a speed of 200r / min for 30min. After being taken out, it was dried at 100℃ for 3h. The organic solvent was recovered to obtain the modified recycled coarse aggregate of the shield tunnel soil. 3) Mix 100 parts by weight of modified shield tunnel soil recycled coarse aggregate, 15 parts by weight of blast furnace slag, 15 parts by weight of secondary fly ash, and 0.5 parts by weight of PVC fiber with 50 parts by weight of water to obtain mixture A. Mix 0.5 parts by weight of polycarboxylate superplasticizer TR-26C, 1 part by weight of sodium silicate, and 0.3 parts by weight of sodium dodecylbenzene sulfonate to obtain mixture B. Stir A and B evenly to obtain shield tunnel soil subgrade material.

[0039] Example 2 The rest is the same as in Example 1, except that in step 1), 10 parts by weight of poly(dimethylsiloxane), bis(3-aminopropyl)-terminated D030172, 50 parts by weight of linear phenolic epoxy resin EPN1179, 50 parts by weight of nano silica DK-SiO2-30 are mixed with the organic solvent tetrahydrofuran to prepare a modified liquid with a solid content of 25%.

[0040] Example 3 The rest is the same as in Example 1, except that in step 1), 10 parts by weight of poly(dimethylsiloxane), bis(3-aminopropyl)-terminated D030172, 80 parts by weight of linear phenolic epoxy resin EPN1179, 50 parts by weight of nano-silica DK-SiO2-30 and organic solvent tetrahydrofuran are mixed to prepare a modified liquid with a solid content of 25%.

[0041] Example 4 The rest is the same as in Example 1, except that in step 1), 30 parts by weight of poly(dimethylsiloxane), bis(3-aminopropyl)-terminated D030172, 50 parts by weight of linear phenolic epoxy resin EPN1179, 50 parts by weight of nano-silica DK-SiO2-30 and organic solvent tetrahydrofuran are mixed to prepare a modified liquid with a solid content of 25%.

[0042] Example 5 The rest is the same as in Example 1, except that in step 1), 30 parts by weight of poly(dimethylsiloxane), bis(3-aminopropyl)-terminated D030172, 80 parts by weight of linear phenolic epoxy resin EPN1179, 30 parts by weight of nano silica DK-SiO2-30 and organic solvent tetrahydrofuran are mixed to prepare a modified liquid with a solid content of 25%.

[0043] Example 6 The rest is the same as in Example 1, except that in step 1), poly(dimethylsiloxane) bis(3-aminopropyl)-terminated D030174 of equal mass is used instead of poly(dimethylsiloxane) bis(3-aminopropyl)-terminated D030172.

[0044] Example 7 The rest is the same as in Example 1, except that in step 1), linear phenolic epoxy resin EPN1179 is replaced with an equal mass of linear phenolic epoxy resin BNE200.

[0045] Example 8 The rest is the same as in Example 1, except that in step 2), the mass-to-volume ratio of the recycled coarse aggregate of the shield soil to the modified liquid is 1 kg: 10 L.

[0046] Example 9 1) Mix 30 parts by weight of poly(dimethylsiloxane), bis(3-aminopropyl)-terminated D030172, 80 parts by weight of linear phenolic epoxy resin EPN1179, 50 parts by weight of nano silica DK-SiO2-30 with the organic solvent tetrahydrofuran to prepare a modified solution with a solid content of 25%. 2) The shield soil in Table 1 is first pre-crushed to a particle size of ≤45mm using a jaw crusher, then ball-milled to a particle size of ≤40mm using a planetary ball mill, and the shield soil with a particle size of 20-40mm is screened out. Then, the shield soil with a particle size of 20-40mm is crushed to a particle size of ≤20mm using an impact crusher, then washed with a spiral sand washer at a speed of 15r / min for 3min, then dewatered using a belt filter press to make the shield soil with a particle size of ≤20mm have a moisture content of 15wt%, and finally dried at 100℃ to a moisture content of 1wt%. The resulting recycled coarse aggregate of shield soil has a particle size of 5-20mm, a water absorption rate of 15%, a crushing value of 40%, a mud content of 6%, and a moisture content of ≤1wt%. The recycled coarse aggregate of the shield tunnel soil was immersed in the modification liquid at a mass-volume ratio of 1kg:20L at 25℃. Under the condition of ultrasonic power of 300W and stirring at a speed of 300r / min for 15min, it was taken out and dried at 100℃ for 3h. At the same time, the organic solvent was recovered to obtain the modified recycled coarse aggregate of the shield tunnel soil. 3) Mix 80 parts by weight of modified shield tunnel soil recycled coarse aggregate, 20 parts by weight of blast furnace slag, 15 parts by weight of secondary fly ash, and 0.5 parts by weight of PVC fiber with 50 parts by weight of water to obtain mixture A. Mix 0.5 parts by weight of polycarboxylate superplasticizer TR-26C, 1 part by weight of sodium silicate, and 0.3 parts by weight of sodium dodecylbenzene sulfonate to obtain mixture B. Stir A and B evenly to obtain shield tunnel soil subgrade material.

[0047] Comparative Example 1 The rest is the same as in Example 1, except that in step 1), the poly(dimethylsiloxane) is replaced with an equal mass of linear phenolic epoxy resin EPN1179, and the bis(3-aminopropyl)-terminated D030172 is used.

[0048] Comparative Example 2 The rest is the same as in Example 1, except that in step 1), the linear phenolic epoxy resin EPN1179 is replaced with an equal mass of poly(dimethylsiloxane), bis(3-aminopropyl)-terminated D030172.

[0049] The materials prepared in the above embodiments and comparative examples were subjected to the following performance tests: Compressive strength: The compressive strength of subgrade materials after 28 days of standard curing was tested according to Appendix D of JTGF80 / 1-2004 Highway Engineering Quality Inspection and Evaluation Standard.

[0050] Freeze-thaw cycle: The compressive strength specimen is placed at -10℃ for 12 hours, and then at 20℃ for 8 hours. This is one cycle. The cycle is repeated 14 times. The compressive strength is then measured again, and the compressive strength decay rate is calculated.

[0051] Water absorption rate: The water absorption rate of the prepared modified shield soil recycled coarse aggregate was tested in accordance with JTG E42-2005 Highway Engineering Aggregate Test Procedure.

[0052] Table 2 Performance Test Results .

[0053] The compressive strength test results from the examples and comparative examples (Table 2) show that poly(dimethylsiloxane), bis(3-aminopropyl) end-capping, and linear phenolic epoxy resin have a synergistic effect in improving compressive strength. It is speculated that poly(dimethylsiloxane) and bis(3-aminopropyl) end-capping reduce surface energy, facilitating the entry of nanofillers into pores and cracks. The physical blocking effect of the nanofillers and the filling effect of the linear phenolic epoxy resin synergistically improve compressive strength. The examples show that the roadbed material prepared by this invention has excellent resistance to freeze-thaw cycles, with a strength loss rate of less than 5% after 14 cycles. The water absorption rate of the modified shield tunnel soil recycled coarse aggregate prepared by this invention is ≤2%.

[0054] The above detailed description is a specific description of one of the feasible embodiments of the present invention. This embodiment is not intended to limit the patent scope of the present invention. All equivalent implementations or modifications that do not depart from the present invention should be included within the scope of the technical solution of the present invention.

Claims

1. A method for producing a modified shield earth regenerative coarse aggregate, characterized by, The method comprises the following steps: 1) preparing a modifying solution with poly(dimethylsiloxane), bis(3-aminopropyl) terminated, linear phenolic epoxy resin, nano filler, and organic solvent; 2) immersing shield tunneling soil recycled coarse aggregate in the modifying solution, stirring under ultrasonic condition, taking out, and drying to obtain modified shield tunneling soil recycled coarse aggregate.

2. The method of claim 1, wherein the modified shield earthwork recycled coarse aggregate is prepared by the steps of: In step 1), the mass ratio of poly(dimethylsiloxane), bis(3-aminopropyl) terminated, linear phenolic epoxy resin, and nano filler is 1-3:5-8:3-5. ​ 3. The method of claim 1, wherein the modified shield earthwork recycled coarse aggregate is prepared by the steps of: In step 1), the number average molecular weight of poly(dimethylsiloxane), bis(3-aminopropyl) terminated, is 1000-3000 g / mol; and the epoxy value of linear phenolic epoxy resin is 0.46-0.

60. ​ 4. The method of claim 1, wherein the modified shield earthwork recycled coarse aggregate is prepared by the steps of: In step 1), the average particle size of nano filler is 30-100 nm; and the nano filler is selected from one or more than two combinations of nano silicon dioxide, nano titanium dioxide, nano calcium carbonate, nano silicon nitride, and nano aluminum oxide. ​ 5. The method of claim 1, wherein the modified shield earthwork recycled coarse aggregate is prepared by the steps of: In step 1), the organic solvent is selected from one or more than two combinations of ethanol, propanol, isopropanol, tetrahydrofuran, and propyl acetate; and the organic solvent makes the solid content of the modifying solution 15-25 wt%. ​ 6. The method of claim 1, wherein the modified shield earthwork recycled coarse aggregate is prepared by the steps of: mixing a mixture of a cement, a fine aggregate, and water; and adding the mixture to a soil to be recycled. In step 2), the mass-to-volume ratio of shield tunneling soil recycled coarse aggregate and modifying solution is 1 kg:10-20 L.

7. The method of claim 1, wherein the modified shield earthwork recycled coarse aggregate is prepared by the steps of: mixing a mixture of a cement, a fine aggregate, and water; and adding the mixture to a soil to be recycled. In step 2), the particle size of shield tunneling soil recycled coarse aggregate is 5-20 mm, the water absorption is 10-15%, the crushing value is 30-40%, the mud content is 3-6%, and the water content is ≤1.6 wt%.

8. The method of claim 1, wherein the modified tunnel soil recycling coarse aggregate is prepared by the steps of: mixing a tunnel soil with a cement, a water, and a superplasticizer to form a mixture; and curing the mixture at a temperature of 20 to 30°C for 7 days or more. In step 2), the shield tunneling soil recycled coarse aggregate is prepared by a method comprising the following steps: pre-crushing, ball milling, crushing, water washing, dewatering, drying, and screening of shield tunneling soil to obtain shield tunneling soil recycled coarse aggregate.

9. The method for preparing modified shield tunnel soil recycled coarse aggregate according to claim 8, characterized in that, The shield earth has moisture content 20-60%, apparent density 1400-1800kg / m 3 , plastic limit 12-30%, liquid limit 25-70%, pH value 6-8, organic matter content≤5%.

10. The use of the modified shield soil recycled coarse aggregate prepared by the method of any one of claims 1-9 in roadbed materials, characterized in that, The roadbed material comprises the following raw materials by mass: 80-100 parts of modified shield tunneling soil recycled coarse aggregate prepared by the method of any one of claims 1-9, 15-20 parts of blast furnace slag, 10-15 parts of fly ash, 0.5-1 part of polycarboxylic acid water reducer, 1-2 parts of alkali activator, 0.3-0.5 parts of polymer fiber, 0.1-0.5 parts of air entraining agent, and 50-70 parts of water.