Roadway slag stone curing agent applied to TBM construction and synchronous backfilling method

Abstract

The invention provides a roadway slag stone curing agent applied to TBM construction and a synchronous backfilling method, and the curing agent comprises the following components in percentage by mass: 30-40% of superfine slag powder, 10-20% of steel slag powder, 10-20% of metakaolin, 20-30% of carbide slag, 3-8% of sodium carbonate and 3-8% of gypsum. Slag stone generated by TBM tunneling is mixed with a curing agent to generate a backfill material, and rapid curing of the slag stone within two hours is achieved; the curing agent is insensitive to the moisture content of the slag stone, and can quickly cure the slag stone to meet the vehicle passing requirement when the water gushing construction environment in a construction roadway is severe.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of TBM construction backfilling, and particularly relates to a roadway slag solidifying agent applied to TBM construction and a synchronous backfilling method. BACKGROUND

[0002] When the roadway bottom is backfilled synchronously in the existing TBM construction, prefabricated inverted arch blocks, cast-in-situ concrete, directly backfilled excavated slag or backfilled modified slag (adding mixed material) can be used. When the prefabricated inverted arch blocks are backfilled, the inverted arch blocks are poured with reinforced concrete, and need to be prefabricated and maintained in a workshop, which is complex in processing and manufacturing, and high in investment. Especially for mine roadways, the service life is relatively short, and the use of prefabricated inverted arch blocks causes waste of steel bars and cement. When the cast-in-situ concrete is backfilled, the concrete needs a long curing period, and vehicles cannot pass through during the curing period, so it is difficult to realize the synchronization of excavation and backfilling, and the investment is increased compared with the slag backfilling. When the slag is directly backfilled, the loose slag has small viscosity, and it is also difficult to be compacted and solidified after being rolled, so the backfilled road surface cannot meet the needs of safe operation of heavy-load vehicles, and is easy to cause the vehicles to overturn or slip; the commonly used added material is cement and lime, and the solidification of the material needs a long time, so the road surface strength can meet the vehicle passing requirements only after the material is solidified (at least 12 hours) when the bottom is paved. In addition, when there is gushing water in the roadway, the construction environment is poor, and the current backfilling method is difficult to quickly meet the vehicle passing requirements. SUMMARY

[0003] The present application aims to at least partly solve one of the technical problems in the related art. To this end, the present application provides a roadway slag solidifying agent applied to TBM construction and a synchronous backfilling method, which uses the slag generated by TBM excavation and a solidifying agent to generate backfilling material, so as to realize the rapid solidification of the slag within two hours; the solidifying agent is not sensitive to the water content of the slag, and the water content of 10% to 16% can meet the rapid vehicle passing requirements, and the slag can also be rapidly solidified to meet the vehicle passing requirements when the construction environment is poor due to gushing water in the construction roadway.

[0004] According to a first aspect of the present application, a roadway slag solidifying agent is provided, which comprises, in terms of mass percentage, 30% to 40% of slag powder, 10% to 20% of steel slag powder, 10% to 20% of metakaolin, 20% to 30% of carbide slag, 3% to 8% of sodium carbonate and 3% to 8% of gypsum.

[0005] In some embodiments, the specific surface area of the slag powder is not less than 400 m 2 / kg; in terms of mass percentage, the content of silicon oxide in the slag powder is 30% to 40%, the content of aluminum oxide is 10% to 20%, and the content of sulfur element is less than 4%, based on the slag powder;

[0006] And / or, the 40-mesh residue of the steel slag powder is not higher than 10%; the content of calcium oxide in the steel slag powder is 40-50% by mass, the content of magnesium oxide is 5-10%, and the content of iron oxide is 20-30% by mass, based on the steel slag powder;

[0007] And / or, the mass percentage of the particle size less than 2 μm in the metakaolin is 70-80%; the content of silicon dioxide is 50-60% and the content of aluminum oxide is 30-40% by mass, based on the metakaolin;

[0008] And / or, the 0.5-mm residue of the carbide slag is not higher than 1%; the content of calcium hydroxide in the carbide slag is greater than 90% by mass;

[0009] And / or, the 80-μm residue of the sodium carbonate is not higher than 5%, and the purity is not lower than 95%;

[0010] And / or, the 0.25-mm residue of the gypsum is not higher than 8%; the content of calcium sulfate in the gypsum is not lower than 80% by mass.

[0011] According to a second aspect of the present application, a TBM tunnel construction synchronous roadway slag stone solidification backfill method is provided, the slag stone generated in TBM tunnel construction is mixed with the solidifying agent in any of the above embodiments to generate backfill material in a mass ratio of 4-5:1, and the backfill work surface in the construction roadway is backfilled.

[0012] In some embodiments, the slag stone has a particle size less than 150 mm.

[0013] In some embodiments, the backfill method comprises the following steps:

[0014] The backfill system is arranged in the construction roadway, and the slag stone generated in TBM tunnel construction and the solidifying agent are used to generate backfill material near the backfill work surface by using the backfill system;

[0015] The backfill material is transported to the backfill work surface and compacted to the designed height after being spread in layers for 20-30 m;

[0016] After curing for 1-2 h, the compressive strength of the backfill body is not lower than 2 MPa, and the backfill work surface is backfilled.

[0017] In some embodiments, the backfill system comprises:

[0018] The transport and screening assembly is used to transport the slag stone generated in TBM tunnel construction to the vicinity of the backfill work surface and screen the slag stone;

[0019] a backfill material generating assembly configured to receive the qualified spoil stones screened by the transport screening assembly and mix the spoil stones with a solidifying agent to obtain the backfill material;

[0020] a road roller assembly configured to transport the backfill material to the backfill working face and compact the backfill material to a designed height after layering and paving;

[0021] a water intercepting assembly arranged in a floor of the backfill working face away from the TBM tunneling face, and configured to collect the gushing water in the construction tunnel and discharge the collected gushing water out of the construction tunnel.

[0022] In some embodiments, the water intercepting assembly comprises at least one water intercepting tank, the water intercepting tank comprising a box body and a grid plate arranged above the box body; the gushing water in the construction tunnel enters the box body through the grid plate and is pumped out of the construction tunnel by a pump.

[0023] In some embodiments, the box body comprises a framework and a plate fixed on both sides and the bottom of the framework.

[0024] In some embodiments, the water intercepting assembly comprises two water intercepting tanks; the two water intercepting tanks are symmetric about a center line of the construction tunnel, one of the water intercepting tanks is configured to intercept water, and the other water intercepting tank is configured to clean silt and sundries.

[0025] In some embodiments, the transport screening assembly comprises a transport member and a screening member; the screening member is arranged on the transport member and close to the backfill working face; the spoil stones generated by the TBM tunneling are transported to the screening member by the transport member for screening, and part of the spoil stones meeting the set requirements are made into the backfill material near the backfill working face; the remaining spoil stones are transported out of the construction tunnel by the transport member.

[0026] In some embodiments, the transport member comprises a first transport machine and a second transport machine; the first transport machine is close to the TBM tunneling face and configured to transport the spoil stones generated by the TBM tunneling to the second transport machine outside the TBM tunneling trailer; the second transport machine is provided with the screening member.

[0027] In some embodiments, the backfill material generating assembly comprises a batching member configured to transport the solidifying agent and mix the solidifying agent with the spoil stones in a set proportion to obtain the backfill material.

[0028] In some embodiments, the road roller assembly comprises a layering machine and a roller machine, wherein the layering machine is configured to transport the backfill material to the backfill working face for layering and paving; and the roller machine is configured to compact the layering and paving backfill material.

[0029] Additional aspects and advantages will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following and the attached drawings. BRIEF DESCRIPTION OF DRAWINGS

[0030] The above and / or additional aspects and advantages of the present application will become apparent and be readily appreciated from the following description, including the accompanying drawings.

[0031] Figure 1 is a schematic diagram of backfilling with prefabricated inverted arch blocks in the related art;

[0032] Figure 2 is a schematic diagram of backfilling with cast-in-place concrete in the related art;

[0033] Figure 3 is a schematic diagram of backfilling with slag in the related art.

[0034] Figure 4 is a schematic diagram of backfilling with modified slag in the related art.

[0035] Figure 5 is a flowchart of a method for backfilling with slag solidification in a TBM tunnel construction synchronous tunnel;

[0036] Figure 6 is a structural schematic diagram of a TBM construction tunnel synchronous slag solidification backfill system according to an embodiment of the present application;

[0037] Figure 7 is a structural schematic diagram of a water intercepting assembly according to an embodiment of the present application;

[0038] Figure 8 is Figure 7 is a B-B top view in FIG. 1.

[0039] In the drawings, 1 is a construction tunnel; 2 is a prefabricated inverted arch block; 3 is cast-in-place concrete; 4 is slag; 5 is modified slag; 6 is a TBM cutterhead; 7 is a trailer; 8 is a first conveyor; 9 is a second conveyor; 10 is a material distributing piece; 11 is distributed slag; 12 is a solidifying agent; 13 is a scraper; 14 is a small road roller; 15 is a water intercepting groove; 16 is backfilling material; 17 is a solidifying bottom; 18 is a framework; 19 is a steel plate; and 20 is a steel grating. DETAILED DESCRIPTION

[0040] The embodiments of the present application are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present application and are not to be construed as limiting the present application. On the contrary, the embodiments of the present application include all variations, modifications, and equivalents that fall within the spirit and scope of the appended claims.

[0041] This application addresses the following existing issues in the related art: The TBM (Transport Block Machine) is currently the world's most technologically advanced tunnel boring equipment, integrating rock breaking, slag removal, slag removal, and support functions, with each process operating in tandem. Compared to drilling and blasting, the TBM excavation method offers advantages such as safety, efficiency, environmental friendliness, and improved surrounding rock stability control. It is widely used in railway, highway, hydropower, and subway tunnel projects. In recent years, several mines in China have adopted TBM excavation for their tunnels. Because the TBM-excavated tunnels have a circular cross-section, personnel and material transportation are frequent during construction, and the curved ground surface is not conducive to the passage of personnel and vehicles. Furthermore, to meet the permanent functional requirements of the construction tunnel, the inactive space at the bottom of the arc must be backfilled. Considering factors such as engineering geological conditions, tunnel function, slope, construction equipment configuration, and investment, the bottom slab backfill method can be post-excavation backfill or simultaneous backfill. Available backfill materials include prefabricated invert blocks, cast-in-place concrete, slag backfill, and improved slag backfill.

[0042] Existing methods of backfilling the base plate have numerous shortcomings, as described below: Backfill after excavation refers to the method where the TBM does not backfill the base plate during tunnel construction. Instead, the base plate is laid from one end to the other after tunnel excavation is completed. When backfilling after excavation is used, rail vehicles are required to transport materials for TBM excavation during tunnel excavation. The track must extend to the end of the TBM trailer. After tunnel excavation is completed, the transport track must be removed for base plate laying, and the base plate must be laid starting from one end of tunnel 1. This process is cumbersome and the construction period is long. Because the operating slope of rail transport vehicles generally does not exceed 0.5%, rail vehicles cannot operate on construction tunnels with larger slopes (e.g., a slope of 10%), making the backfill after excavation unsuitable.

[0043] Synchronous backfilling involves simultaneous excavation of the construction tunnel 1 and floor backfilling during TBM construction. The same backfill materials can be used for both post-breakthrough backfilling and synchronous backfilling. Synchronous backfilling includes backfilling with precast invert blocks 2, backfilling with cast-in-place concrete 3, direct backfilling with slag 4, and backfilling with modified slag 5.

[0044] When backfilling with prefabricated invert block 2 Figure 1As shown, the prefabricated inverted arch block 2 is made of reinforced concrete and needs to be prefabricated and maintained in the workshop, which is high in investment, especially for some mine tunnels with short service life, and the use of prefabricated inverted arch block 2 causes waste of steel bars and cement. For example, a related technology discloses a TBM tunneling and inverted arch synchronous construction method. The main steps of the method are as follows: step A, arranging a material transport track during the TBM tunneling process, then connecting two material turnover plate cars in a head-to-tail manner at the end of the TBM trailer; step B, pre-installing corbels on the initial support arch frame during TBM tunneling construction, then building a hoisting track beam on the surface of the installed corbel, and then laying steel rails on the hoisting track beam and installing both ends of the gantry crane device on the steel rails; step C, transporting materials from outside the hole to the material unloading area by the material transport train, and then transporting the materials from the material unloading area by the gantry crane device; step D, as the TBM advances, the steel rails, corbels and hoisting track beams are repeatedly shifted forward.

[0045] When using cast-in-place concrete 3 backfilling, as shown in Figure 2 , due to the long curing period of concrete, vehicles cannot pass through during the curing period, making it difficult to achieve synchronous tunneling and backfilling; compared with using slag 4 backfilling, the investment increases.

[0046] When using slag 4 direct backfilling, as shown in Figure 3 , due to the small viscosity of loose slag 4, it is also difficult to compact and consolidate after rolling, and the backfilled road surface cannot meet the safety operation needs of heavy load vehicles, which is easy to cause vehicle overturning or skidding. Using slag 4 direct backfilling is only suitable for the case where single-track hoists and other equipment are used to transport materials during construction, and the amount of automobile transportation is small.

[0047] When using improved slag 5 backfilling, as shown in Figure 4 , the commonly used added materials are cement and lime, etc. Due to the long solidification time of such materials, the road surface strength can meet the vehicle passing requirements only after the materials are solidified (at least 24 hours) when paving the bottom, making it difficult to achieve synchronous tunneling and backfilling. When there is water gushing in the construction tunnel 1, the construction environment is poor, and this backfilling method is even more difficult to quickly meet the vehicle passing requirements.

[0048] To address the above-mentioned problems, the present application provides a tunnel slag solidifying agent and a synchronous backfilling method for TBM construction. The solidifying agent includes slag powder, steel slag powder, metakaolin, carbide slag, sodium carbonate, and gypsum. The resulting solidifying agent is insensitive to the moisture content of the slag. Even when there is water gushing in the construction tunnel and the construction environment is harsh, the slag can be quickly solidified to meet vehicle traffic requirements. Regarding the synchronous tunnel slag solidification and backfilling method for TBM tunnel construction, the slag produced by TBM tunnel construction is mixed with the solidifying agent in any of the above-mentioned embodiments at a mass ratio of 4 to 5:1 to generate a backfill material. The backfill working surface in the construction tunnel is backfilled, and the compressive strength of the backfill body is not less than 2 MPa 1-2 hours after backfilling, achieving rapid backfilling of the backfill working surface, fast solidification speed, and strength and durability of the backfill body.

[0049] According to the first aspect of the present application, a tunnel slag solidifier is proposed, which includes, in terms of mass percentage, 30% to 40% slag fine powder, 10% to 20% steel slag powder, 10% to 20% metakaolin, 20% to 30% carbide slag, 3% to 8% sodium carbonate and 3% to 8% gypsum.

[0050] The specific surface area of ​​slag powder is not less than 400m 2 / kg; the activity index is not less than 75% at 7d and not less than 90% at 28d. The main component of slag micropowder is aluminosilicate glass. Based on the slag micropowder and calculated by mass percentage, the silicon oxide content in the slag micropowder is 30% to 40%, the aluminum oxide content is 10% to 20%, and the sulfur content is less than 4%. Among them, the slag micropowder is used to stimulate the active components, and it is a material with potential water-hardening properties. During the application of the curing agent and the curing process of the curing agent and the slag stone, the sodium carbonate and carbide slag in this application provide an alkaline environment, which can activate the active aluminosilicate components in the slag micropowder. The sodium ions dissociated from sodium carbonate will destroy the silicon-oxygen (Si-O) and aluminum-oxygen (Al-O) bonds of the glass structure in the slag micropowder, thereby releasing the active SiO2 and Al2O3 therein. The active SiO2 and Al2O3 react with the calcium ions (Ca) provided by the carbide slag. 2+ ) reacts. The calcium hydroxide in the carbide slag dissolves to provide rich Ca 2+ These ions react with active aluminosilicates to form calcium silicate hydrate (CSH) gel and calcium aluminate hydrate (CAH) gel. CSH gel is a substance with good gelling properties. It forms a bonding network between particles, wrapping and bonding the slag particles together.

[0051] In some embodiments, the content of the slag powder in the roadway slag stone solidifying agent is 30% to 40% by mass percentage, for example, the content of the slag powder is 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, etc.; when the content of the slag powder in the roadway slag stone solidifying agent is too small, for example, less than 30%, the total amount of active silicate in the obtained solidifying agent is insufficient, the gelling product is reduced, and finally the strength of the solidified slag stone is reduced; when the content of the slag powder in the roadway slag stone solidifying agent is too large, for example, greater than 40%, the obtained solidifying agent is prone to increase the unactivated slag powder, reduce the reaction efficiency, and the unactivated slag powder becomes a weak point of the structure of the solidified slag stone, resulting in reduced strength.

[0052] In the present embodiment, the 40-mesh sieve residue of the steel slag powder is not higher than 10%, and the activity index thereof is not less than 70% at 7d and not less than 80% at 28d. The steel slag powder contains calcium oxide, magnesium oxide, iron oxide, etc. In terms of mass percentage, the content of calcium oxide in the steel slag powder is 40% to 50%, the content of magnesium oxide is 5% to 10%, and the content of iron oxide is 20% to 30%.

[0053] The steel slag powder is mainly used to supplement active ingredients and can play a role of crystal nucleus. The steel slag powder contains a certain amount of active ingredients such as calcium oxide, which can participate in the alkali activation reaction, supplement calcium ions, and promote the generation of gel products. The calcium oxide in the steel slag powder can react with the active ingredients in the slag powder and metakaolin, further enhancing the amount and quality of the gel. At the same time, the components such as iron oxide in the steel slag powder can play a role of crystal nucleus. In the process of gel product generation, it is beneficial to the growth and precipitation of the gel on the surface thereof. For example, in the early stage of the reaction, the gel product will preferentially form on the surface of the steel slag powder particles, and as the reaction proceeds, it will gradually fill the gaps between the slag stones, making the solidified body more compact, and also helping to improve the early strength of the solidified backfill body.

[0054] In some embodiments, the content of the steel slag powder in the roadway slag stone solidifying agent is 10% to 20% by mass percentage, for example, the content of the steel slag powder is 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, etc.; when the content of the steel slag powder in the roadway slag stone solidifying agent is too small, for example, less than 10%, the solidified slag stone obtained by the solidifying agent has low compactness, which is not conducive to the growth of early strength; when the content of the steel slag powder in the roadway slag stone solidifying agent is too large, for example, greater than 20%, the excess free CaO in the obtained solidifying agent will hydrolyze, leading to the expansion and cracking of the solidified slag stone in the later stage (poor stability), and at the same time, the dilution of the effective gelling components will result in reduced strength of the solidified slag stone.

[0055] In the present embodiment, the mass percentage of the metakaolin with a particle size less than 2 μm is 70% to 80%, and the activity index of the metakaolin is not less than 80% at 7d and not less than 90% at 28d; the main components of the metakaolin are silicon dioxide and aluminum oxide, and the content of the silicon dioxide is 50% to 60% and the content of the aluminum oxide is 30% to 40% according to the mass percentage.

[0056] The metakaolin mainly participates in the activity reaction of the solidifying agent and improves the solidification performance of the slag stone, and the metakaolin is rich in active silicon dioxide and aluminum oxide, which can react with sodium ions in sodium carbonate and calcium ions in the carbide slag under the condition of alkali excitation. The gel product generated by the reaction of the active components in the metakaolin with other components can fill in the pores of the slag stone, and improve the microstructure of the solidified body. In addition, the addition of the metakaolin can also adjust the workability of the solidifying agent, so that it has better plasticity and water retention. This helps the solidifying agent to better wrap the slag stone particles, so that the slag stone particles are more uniformly distributed in the solidification process, thereby improving the overall performance of the solidified backfill body.

[0057] In some embodiments, the content of the metakaolin in the roadway slag solidifying agent is 10% to 20% according to the mass percentage, for example, the content of the metakaolin is 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, etc.; when the content of the metakaolin in the roadway slag solidifying agent is too small, such as less than 10%, the obtained solidified early active aluminum source is insufficient, and the C-A-H gel is less, which leads to the decrease of the water stability of the solidified slag stone; when the content of the metakaolin in the roadway slag solidifying agent is too large, such as greater than 20%, the cost of the obtained solidifying agent is high, and the specific surface area increases, which leads to the increase of the water demand of the solidifying agent and affects the construction performance of the material.

[0058] In the present embodiment, the residual amount of the carbide slag on the 0.5 mm square hole screen is not higher than 1%; the content of calcium hydroxide in the carbide slag is greater than 90% according to the mass percentage; and the main role of the carbide slag is to provide an alkaline environment and calcium ions. The main component of the carbide slag is calcium hydroxide, and the alkaline environment thereof helps to excite the activity of the slag powder, the metakaolin and other materials. At the same time, a large amount of Ca 2+ These calcium ions are the key raw materials for generating calcium silicate hydrate (C-S-H) gel and calcium aluminate hydrate (C-A-H) gel, and play a crucial role in the strength development of the solidified backfill body.

[0059] In some embodiments, the content of carbide slag in the roadway slag solidification agent is 20% to 30% by mass percentage, for example, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, etc. When the content of carbide slag in the roadway slag solidification agent is too small, for example, less than 20%, the obtained solidification agent is weakly alkaline, the active components of slag are not fully released, and the strength of the solidified slag is seriously insufficient. When the content of carbide slag in the roadway slag solidification agent is too large, for example, greater than 30%, the obtained solidification agent releases excessive Ca(OH)2, resulting in loose structure and reduced interfacial adhesion, which affects the structural durability of the solidified slag.

[0060] In the present embodiment, the content of sodium carbonate in the 80 μm square mesh sieve is not more than 5%, and the purity is not less than 95%. The role of sodium carbonate in the solidification agent is alkaline activation. Sodium carbonate is a key factor in the alkaline activation process, which can destroy the glass structure of slag powder, steel slag powder, metakaolin and other materials, and release the active components therein. Sodium carbonate can initiate polymerization by providing sodium ions, and promote the reaction of active silicate and calcium ions to generate hydrated products with cementitious properties, such as C-S-H gel and N-A-S-H (alkali-activated silicate-hydrated) gel, so that the solidified material has cementitious properties and realizes the solidification of slag.

[0061] In some embodiments, the content of sodium carbonate in the roadway slag solidification agent is 3% to 8% by mass percentage, for example, 3%, 4%, 5%, 6%, 7%, 8%, etc. When the content of sodium carbonate in the roadway slag solidification agent is too small, for example, less than 3%, the obtained solidification agent is insufficiently alkaline, and the strength of the solidified slag increases slowly. When the content of sodium carbonate in the roadway slag solidification agent is too large, for example, greater than 8%, the obtained solidification agent has excessive sodium ions, resulting in the precipitation of salt crystals and reducing the durability.

[0062] In the present embodiment, the content of gypsum in the 0.25 mm square mesh sieve is not more than 8%. The content of calcium sulfate in the gypsum is not less than 80% by mass percentage. Gypsum has the effect of adjusting the setting time in the solidification process, which can prevent the solidified material from setting too quickly and ensure sufficient time for stirring, molding and other operations. For example, if there is no adjustment of gypsum, the solidified material may set in a short time, resulting in insufficient filling of the space between the slag. Secondly, gypsum also has the effect of generating filling products, and the calcium sulfate component in the gypsum can react with calcium ions, aluminum ions and other ions in the system to generate ettringite and other products. Ettringite is a needle-shaped crystal that can fill the pores, and also contributes to the strength and volume stability of the solidified backfill. At the same time, the generation of ettringite can also reduce the porosity of the solidified body, improve its impermeability, and thus enhance the durability of the solidified backfill.

[0063] In some embodiments, the gypsum in the roadway slag solidifying agent is 3% to 8% by mass percentage, for example, 3%, 4%, 5%, 6%, 7%, 8%, etc. When the content of gypsum in the roadway slag solidifying agent is too small, such as less than 3%, the setting time of the obtained solidifying agent cannot be effectively adjusted, affecting the construction performance. When the content of gypsum in the roadway slag solidifying agent is too large, such as greater than 8%, the obtained solidifying agent has excessive gypsum, leading to the generation of secondary ettringite in the later stage, causing the volume expansion and cracking of the solidified slag.

[0064] The solidifying agent 12 in the present application is green and environmentally friendly, and has a lower price than cement. It only needs to be uniformly mixed with slag, which is convenient to construct. The raw materials are widely available, and slag powder, steel slag powder, metakaolin and calcium carbide slag realize the environmental utilization of industrial waste or natural materials. The production process has low energy consumption and less pollution emission, and no volatile organic compounds are emitted during use. The solidifying agent in the present application is not sensitive to the water content of slag. In the case of poor construction environment with water gushing in the construction roadway, the slag can also be quickly solidified to meet the vehicle passing requirements.

[0065] According to the second aspect of the present application, a TBM roadway construction synchronous roadway slag solidifying backfill method is provided. The slag generated by TBM roadway construction is mixed with the solidifying agent in any of the above embodiments according to a mass ratio of 4 to 5:1 to generate backfill material, which is used for backfilling the working face in the construction roadway.

[0066] The gradation of the excavated waste slag is not strictly required, and the slag particle size is less than 150 mm. In the present application, the slag generated by TBM roadway construction is mixed with the solidifying agent in any of the above embodiments according to a mass ratio of 4 to 5:1 to generate backfill material. A reasonable ratio of slag to solidifying agent can ensure that there is enough solidifying agent to wrap and bond the slag particles. The solidifying agent fills the gaps between the slag particles, and through the generation and crystallization of the gel product, the slag is tightly bonded together to form a backfill material with a reasonable filling structure after solidification. If the slag ratio is too high, the solidifying agent is not enough to fill the gaps and bond the particles, which will lead to a decrease in the strength and durability of the solidified backfill body. Conversely, if the solidifying agent ratio is too high, it will increase the cost and may cause problems such as shrinkage of the solidified body, affecting its performance.

[0067] In some embodiments, the backfill method is as follows Figure 5 comprising the following steps;

[0068] S1: arranging a backfill system in the construction roadway, and using the backfill system to generate backfill material from the slag generated by TBM roadway construction and the solidifying agent near the backfill working face;

[0069] S2: transporting the backfill material to the backfill working face and layering and paving 20 to 30 m, and then compacting to the design height;

[0070] S3: After curing for 1-2 hours, the compressive strength of the backfill body shall not be less than 2MPa, and the backfill working surface shall be completed.

[0071] In S1, a backfill system is arranged in the construction tunnel, and the backfill system is used to convert the slag and curing agent generated by the TBM tunnel construction into backfill material near the backfill working face. The backfill system includes: a transport screening component, a backfill material generation component, a roller compaction component, and a water cutoff component. The transport screening component is used to transport the slag generated by the TBM excavation in the construction tunnel 1 to the vicinity of the backfill working face and screen it. The backfill material generation component receives the slag that meets the requirements screened by the transport screening component, and mixes the slag with the curing agent to obtain backfill material 16; the roller compaction component transports the backfill material 16 to the backfill working face and spreads it in layers and compacts it to the designed height; the water cutoff component is set in the bottom plate of the backfill working face away from the TBM excavation face, and is used to collect the gushing water in the construction tunnel 1 and discharge the collected gushing water out of the construction tunnel 1.

[0072] Among them Figure 6 As shown, the excavation direction of TBM is as follows Figure 6 As shown by the arrow in Figure 6 Taking the left and right directions indicated in the figure as an example, the TBM excavation construction direction is from right to left, and the TBM cutterhead 6 is located on the left side of the construction tunnel 1, wherein the tail of the TBM cutterhead 6 is the trailer 7. During the excavation construction of the construction tunnel 1 of the TBM, slag is generated. The slag is transported to the vicinity of the backfill working face using the transport and screening assembly of the present application, and the slag is screened. The qualified slag is used as the separation slag 11 for the subsequent production of backfill material 16.

[0073] The transport and screening assembly includes a transport part and a dividing part 10; the dividing part 10 is arranged on the transport part and near the backfill working face; the slag generated by TBM excavation is transported to the dividing part 10 for screening through the transport part, and some of the slag that meets the set requirements can be the dividing slag 11, that is, slag with high hardness and good water resistance can be selected as the dividing slag 11 according to the geological conditions of the surrounding rock, and the dividing slag 11 is made into backfill material 16 near the backfill working face; the remaining slag is transported to the outside of the construction tunnel 1 by the transport part.

[0074] The transporters include a first transporter 8 and a second transporter 9, which can be belt conveyors or can be vehicles or rail transport devices, etc. The first transporter 8 is close to the TBM tunneling face and is used to transport the muck generated by the TBM tunneling to the second transporter 9 outside the TBM tunneling trailer 7. The second transporter 9 is provided with a material distributing device 10 near the backfilling face. The material distributing device 10 can be an automatic material distributing device or a manual material distributing device. The automatic material distributing device can be a belt material distributing device, which is a common device in the art and will not be described in detail. The material distributing device 10 screens the muck on the second transporter 9. Part of the screened muck 11 that meets the set requirements is made into backfilling material 16 near the backfilling face. The remaining muck is transported to the outside of the construction tunnel 1 by the second transporter 9.

[0075] In some embodiments, the backfilling material generating assembly includes a material mixing device for transporting the solidifying agent 12 and mixing the solidifying agent 12 with the screened muck 11 in a set ratio to obtain the backfilling material 16.

[0076] The material mixing device includes a shovel mechanical device for transporting the solidifying agent 12 outside the construction tunnel 1 to the place where the screened muck 11 is placed in the construction tunnel 1. The shovel mechanical device mixes the solidifying agent 12 with the screened muck 11 in a set ratio to obtain the backfilling material 16.

[0077] Therefore, the backfilling material 16 in the present application does not need to add cement, the raw materials are widely sourced, green and environmentally friendly, and the industrial waste or natural materials such as slag powder, steel slag powder, metakaolin and calcium carbide slag realize the environmental protection utilization. The production process has low energy consumption and less pollution emission, and there is no volatile organic compound emission during use. In addition, when the ratio of the screened muck 11 to the solidifying agent 12 in the present application is 4:1-5:1, enough solidifying agent 12 can be ensured to wrap and bond the muck particles. The solidifying agent 12 fills the gaps between the screened muck 11 particles, and through the generation and crystallization of the gel product, the screened muck 11 is tightly bonded together.

[0078] In some embodiments, the water intercepting assembly includes at least one water intercepting tank 15, which includes a box body and a grid plate arranged above the box body. The gushing water in the construction tunnel 1 enters the box body through the grid plate and is pumped to the outside of the construction tunnel 1 by a pump.

[0079] The box body includes a skeleton 18 and a plate fixed on both sides and the bottom of the skeleton 18. The skeleton 18 is welded by equal angle steel (L80*80*10), and bolt holes are reserved on the skeleton 18 for on-site assembly by bolts. The 8mm thick steel plate 19 is welded on both sides and the bottom of the skeleton 18. The top of the box body is paved with a grid plate, and the grid plate is a steel grid plate 20, so that personnel and vehicles can pass normally. The gushing water in the construction tunnel 1 flows into the box body through the gap between the grid plates, and the accumulated water in the box body is discharged out of the construction tunnel 1 by a pump such as a water pump.

[0080] As shown in Figures 7-8 The water intercepting assembly is arranged in the laid bottom plate away from the TBM cutterhead side, and the water intercepting assembly includes two water intercepting grooves 15. Figure 7 The A-A sectional view in Figure 8

[0081] Figure 8 The B-B plan view in Figure 7 The two water intercepting grooves 15 are assembled water intercepting grooves, and the two water intercepting grooves 15 are symmetrical about the center line of the construction tunnel 1 and work independently. One water intercepting groove 15 is used for intercepting water, and the other water intercepting groove 15 is used for cleaning silt and sundries. When there is gushing water in the construction tunnel, the working environment is improved and the backfill quality is improved.

[0082] In some embodiments, the road roller compaction assembly includes a paving machine and a roller, wherein the paving machine transports the backfill material 16 to the backfill working surface for layering and paving, and the roller compacts the layered and paved backfill material 16. The paving machine can be a scraper mechanical device, and the scraper mechanical device can be a scraper 13. In S2, the backfill material 16 is scooped to the backfill working surface for layering and paving, and the backfill length is generally 20-30m, which can also be determined according to actual needs, such as shown in Figure 8 Then, the roller such as a small road roller 14 is used for compaction to meet the design requirements; the layered and paved backfill material is compacted to the design height. In S3, after 1-2 hours of maintenance, the backfill body forms a solid bottom 17 when the compressive strength is not less than 2MPa, and vehicles can pass normally, and then the next bottom paving work cycle is started.

[0083] ​The backfill material generated by the solidifying agent in the present application and the slag generated by the TBM roadway construction can truly realize the synchronization of TBM roadway excavation and backfilling, and the backfill material can be quickly solidified in about 2 hours to meet the vehicle passing requirements, thereby greatly improving the backfill efficiency. Meanwhile, the backfill material fully utilizes the slag generated by the excavation, realizes waste utilization, and the solidifying agent and the slag can be mixed at the tail of the TBM trailer to meet the requirements, thereby reducing the production cost, transportation and transshipment. The water interception assembly reduces the influence of the roadway gushing water on the bottom backfilling, improves the working environment and improves the backfill quality. Therefore, compared with the prefabricated inverted arch block backfilling and the cast-in-place concrete backfilling, the present application saves the cement consumption and has low investment.

[0084] In order to further illustrate the solidifying agent in the present application, the following examples will be given. In the following examples, the specific surface area of the slag powder is not less than 400 m 2 / kg; the content of silicon oxide in the slag powder is 30% to 40%, the content of aluminum oxide is 10% to 20%, and the content of sulfur element is less than 4% by mass percentage. The 40-mesh screen residue of the steel slag powder is not more than 10%; the content of calcium oxide in the steel slag powder is 40% to 50%, the content of magnesium oxide is 5% to 10%, and the content of iron oxide is 20% to 30% by mass percentage. The mass percentage of the particle size less than 2 μm in the metakaolin is 70% to 80%; the content of silicon dioxide in the metakaolin is 50% to 60%, and the content of aluminum oxide is 30% to 40% by mass percentage. The 0.5-mm screen residue of the carbide slag is not more than 1%; the content of calcium hydroxide in the carbide slag is more than 90% by mass percentage. The 80-μm screen residue of the sodium carbonate is not more than 5%, and the purity is not less than 95%. The 0.25-mm screen residue of the gypsum is not more than 8%; the content of calcium sulfate in the gypsum is not less than 80% by mass percentage.

[0085] Example 1

[0086] The present example provides a roadway slag solidifying agent, which includes, by mass percentage, 36% of slag powder, 18% of steel slag powder, 15% of metakaolin, 25% of carbide slag, 3% of sodium carbonate and 3% of gypsum.

[0087] Example 2

[0088] The present example provides a roadway slag solidifying agent, which includes, by mass percentage, 35% of slag powder, 15% of steel slag powder, 15% of metakaolin, 25% of carbide slag, 5% of sodium carbonate and 5% of gypsum.

[0089] Example 3

[0090] The embodiment provides a roadway slag stone curing agent, which comprises, in percentage by mass, slag powder 34%, steel slag powder 10%, metakaolin 10%, carbide slag 30%, sodium carbonate 8% and gypsum 8%.

[0091] Comparative Example 1

[0092] The comparative example provides a roadway slag stone curing agent, which comprises, in percentage by mass, slag powder 25%, steel slag powder 17%, metakaolin 17%, carbide slag 29%, sodium carbonate 6% and gypsum 6%.

[0093] In the comparative examples 2 to 12, the percentage by mass of the slag powder, the steel slag powder, the metakaolin, the carbide slag, the sodium carbonate and the gypsum is adjusted according to the changes in Table 1.

[0094] Table 1 Composition table of the roadway slag stone curing agent in the comparative examples 2 to 12

[0095] Mineral slag fines Steel slag fines Metakaolin Carbide slag Sodium carbonate Gypsum Comparative Example 2 45 13 13 21 4 4 Comparative Example 3 39 5 17 28 6 6 Comparative Example 4 31 25 13 22 4 4 Comparative Example 5 39 17 5 28 6 6 Comparative Example 6 31 13 25 22 4 4 Comparative Example 7 40 17 17 15 6 6 Comparative Example 8 30 13 13 35 4 4 Comparative Example 9 36 15 15 26 2 5 Comparative Example 10 31 13 13 22 15 4 Comparative Example 11 36 16 16 26 5 1 Comparative Example 12 33 14 14 24 5 10

[0096] Experimental Example 1

[0097] The roadway slag stone curing agents in the examples and the comparative examples are all stirred uniformly in a powder state, water is added, and test blocks are prepared under the condition of maximum dry density, the test blocks are cylindrical test blocks with a size of 50 mm in diameter and 50 mm in height, and then the test blocks are put into a standard curing box for curing. The strength of the obtained cylindrical test blocks is detected, and the detection results are shown in Table 2.

[0098] Table 2 Strength detection results of different cylindrical test blocks

[0099]

[0100]

[0101] The strength of the cured slag stone of the cylindrical test block 8 is reduced because the total amount of active silicate is insufficient, and the cementitious product is reduced. The cylindrical test block 9 has a crack fault. The cured slag stone of the cylindrical test block 10 has a low density, which is not conducive to the growth of early strength. The cured slag stone of the cylindrical test block 11 has a late volume expansion and cracking, and the strength of the cured slag stone is reduced. The 28D water stability of the cylindrical test block 12 is reduced. The cost of the curing agent of the cylindrical test block 13 is relatively high. The strength of the cylindrical test block 14 is seriously insufficient. The structure of the cylindrical test block 15 is loose, the interfacial bonding force is reduced, and the water stability coefficient is significantly reduced. The strength of the cured slag stone of the cylindrical test block 16 grows slowly. The water stability coefficient of the cylindrical test block 17 is significantly reduced, and the durability is seriously reduced. The setting time of the cylindrical test block 18 cannot be effectively adjusted, which affects the construction performance. The secondary ettringite of the cylindrical test block 19 is generated in the later period, which causes the volume expansion and cracking of the cured slag stone.

[0102] In summary, low or high levels of any curing agent component can lead to abnormal workability, durability risks, and uneven strength. Examples of abnormal workability include: uncontrolled setting time (too fast / too slow), increased water demand, and impacted workability. Durability risks include: excessive components introducing expansive products or impurities, leading to cracking, corrosion, and low water stability coefficients. Uneven strength includes: insufficient early / late strength, decreased adhesion, and failure to meet long-term service requirements.

[0103] Experimental Example 2

[0104] The roadway slag solidifiers from each Example 2 were uniformly mixed in powder form, then mixed with waste rock of varying mass, and water was added. Test blocks were prepared at maximum dry density. The test blocks were cylindrical, 100 mm in diameter and 100 mm in height. The blocks were then placed in a standard curing chamber for curing. The resulting cylindrical test blocks were subjected to strength testing, with the results shown in Table 3.

[0105] Table 3 Strength test results of different cylindrical test blocks

[0106]

[0107] From the results in Table 3, it can be seen that the optimal ratio of waste rock / hardener is in the range of 4 to 5:1, which can form backfill materials that meet the requirements of rapid TBM formation. If the hardener ratio is too high, the lack of waste rock aggregate filling effect will lead to a slight decrease in strength and higher cost. If the hardener ratio is too low, the backfill material will have insufficient bonding strength, resulting in looseness and many holes, which will seriously affect the strength and water stability.

[0108] It should be noted that, in the description of this application, the terms "first", "second", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance. In addition, in the description of this application, unless otherwise specified, the meaning of "plurality" is two or more.

[0109] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, segment or portion of code comprising one or more executable instructions for implementing the steps of a specific logical function or process, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may be performed out of the order shown or discussed, including performing functions in a substantially simultaneous manner or in the reverse order depending on the functions involved, which should be understood by those skilled in the art to which the embodiments of the present application belong.

[0110] In the description of the specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are contained in at least one embodiment or example of the present application. In the specification, the illustrative description of the above terms does not necessarily mean the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0111] Although the embodiments of the present application have been shown and described above, it is understood that the above-described embodiments are exemplary, and cannot be construed as limiting the present application, and those skilled in the art can make changes, modifications, replacements and variations to the above-described embodiments within the scope of the present application.

Claims

1. A roadway slag solidifying agent, characterized in that: Calculated by mass percentage, it includes 30% to 40% of slag powder, 10% to 20% of steel slag powder, 10% to 20% of metakaolin, 20% to 30% of carbide slag, 3% to 8% of sodium carbonate and 3% to 8% of gypsum.

2. The curing agent according to claim 1, characterized in that The specific surface area of ​​the slag powder is not less than 400m 2 / kg; based on the slag powder, the silicon oxide content in the slag powder is 30% to 40%, the aluminum oxide content is 10% to 20%, and the sulfur content is less than 4% according to the mass percentage; and / or, the 40-mesh sieve residue of the steel slag powder is not higher than 10%; based on the steel slag powder, the calcium oxide content of the steel slag powder is 40% to 50%, the magnesium oxide content is 5% to 10%, and the iron oxide content is 20% to 30% in terms of mass percentage; And / or, the mass percentage of particles smaller than 2 μm in the metakaolin is 70% to 80%; based on the metakaolin, the silica content in the metakaolin is 50% to 60% and the alumina content is 30% to 40% in terms of mass percentage; And / or, the 0.5mm sieve residue of the carbide slag is not higher than 1%; wherein the calcium hydroxide content in the carbide slag is greater than 90% in terms of mass percentage; and / or, the sodium carbonate has an 80 μm sieve residue of not more than 5% and a purity of not less than 95%; And / or, the 0.25 mm sieve residue of the gypsum is not higher than 8%; wherein the calcium sulfate content in the gypsum is not lower than 80% in terms of mass percentage.

3. A method for synchronous tunnel slag solidification and backfilling during TBM tunnel construction, characterized in that: The slag produced during TBM tunnel construction is mixed with the curing agent according to claim 1 or 2 in a mass ratio of 4 to 5:1 to generate backfill material, which is then used to backfill the working surface in the construction tunnel.

4. The backfilling method according to claim 3, characterized in that: The particle size of the slag is less than 150 mm.

5. The backfilling method according to claim 3, characterized in that: The method includes the following steps: Arranging a backfill system in the construction tunnel, and utilizing the backfill system to convert the slag and the curing agent into backfill material near the backfill working surface; The backfill material is transported to the backfill working surface and spread in layers of 20m to 30m and then compacted to the designed height; After curing for 1-2 hours, the compressive strength of the backfill body shall not be less than 2MPa, and the backfill working surface shall be completed.

6. The backfilling method according to claim 5, characterized in that: The backfill system includes: The transport and screening component is used to transport the slag generated by TBM excavation in the construction tunnel to the vicinity of the backfill working face and screen it; a backfill material generating assembly, which receives the slag and stone that meet the requirements screened by the transport screening assembly, and mixes the slag and stone with a curing agent to obtain backfill material; A roller compactor assembly transports the backfill material to the backfill working surface and spreads it in layers before compacting it to the designed height; and The water cut-off assembly is arranged in the bottom plate of the backfill working face away from the TBM excavation face, and is used to collect the gushing water in the construction tunnel and discharge the collected gushing water out of the construction tunnel.

7. The backfilling method according to claim 6, characterized in that: The water interception assembly includes at least one water interception trough, which includes a box body and a grid plate arranged above the box body; the gushing water in the construction tunnel enters the box body through the grid plate and is pumped out of the construction tunnel through a pump.

8. The backfilling method according to claim 7, characterized in that: The box body comprises a frame and plates fixed on both sides and the bottom of the frame.

9. The backfilling method according to claim 7 or 8, characterized in that: The water-cutting assembly includes two water-cutting grooves; the two water-cutting grooves are symmetrical about the center line of the construction tunnel, one of the water-cutting grooves is used for cutting water, and the other water-cutting groove is used for cleaning silt and debris.

10. The backfilling method according to claim 9, characterized in that: The transport and screening assembly includes a transport part and a material dividing part; the material dividing part is arranged on the transport part and near the backfill working surface; the slag generated by TBM excavation is transported to the material dividing part for screening through the transport part, and some of the slag that meets the set requirements is made into the backfill material near the backfill working surface; the remaining slag is transported to the outside of the construction tunnel through the transport part.

11. The backfilling method according to claim 10, characterized in that: The transport parts include a first transporter and a second transporter; the first transporter is close to the TBM excavation face and is used to transport the slag and rock produced by the TBM excavation to the second transporter outside the TBM excavation trailer; the second transporter is provided with the material dividing part.

12. The backfilling method according to claim 9, characterized in that: The backfill material generating assembly includes a batching component, which is used to transport the curing agent and mix the curing agent with the slag stone in a set ratio to obtain the backfill material.

13. The backfilling method according to claim 9, characterized in that: The road rolling assembly includes a paver and a roller, wherein the paver transports the backfill material to the backfill working surface for layered paving; and the roller compacts the layered paved backfill material.

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