Construction Technology of Lining for Small Cross-section Tunnel

Abstract

This application relates to the field of tunnel construction in water conservancy projects, and specifically discloses a construction technology for lining small-section tunnels. The construction technology for lining small-section tunnels includes: S1, cleaning the base after invert excavation; S2, pouring reinforced concrete in the invert; S3, binding the steel bars of the arch wall and pouring concrete; S4, curing after the arch wall concrete reaches a certain strength; the arch wall concrete is composed of raw materials including the following parts by weight: 900-1200 parts of coarse aggregate, 600-800 parts of fine aggregate, 240-300 parts of cement, 60-100 parts of fly ash, 50-70 parts of mineral powder, 140-190 parts of water, 7-11 parts of water reducer, and 35-65 parts of shielding absorbent, and the shielding absorbent includes konjac mannan, zirconium hydroxide modified chitosan, and flocculation components. The construction technology for lining small-section tunnels of this application can be used for construction in the saline soil environment of arid areas, and has the advantage of extending the service life of the water conveyance tunnel.

Description

Technical Field

[0001] This application relates to the field of tunnel construction in water conservancy projects, and more specifically, to the lining construction technology for small-section tunnels. Background Art

[0002] In the operation of tunnel construction in water conservancy projects, the minimum cross-section diameter is about 3.5 m. Tunnels with such cross-section diameters are called small-section tunnels. After the tunnel excavation, in order to maintain the stability of the surrounding rocks after excavation and prevent large deformations, initial support and secondary lining construction need to be carried out on the excavation section.

[0003] Tunnel lining usually follows the principle of "inverted arch in advance, integral lining of arch and wall". After the initial support is completed, in order to effectively control its deformation, the inverted arch is constructed as closely as possible to the excavation face. The inverted arch filling uses a trestle platform to solve the problem of in-tunnel transportation, and is constructed in one full width at a time. After the inverted arch is constructed, the waterproof board is manually laid using the operation platform. After tying the steel bars, the secondary lining is carried out using a lining trolley, and the arch and wall are poured integrally at one time.

[0004] Facing the saline soil commonly found in arid and cold regions, due to the corrosion of the concrete in the tunnel by a large number of erosive salt ions such as soluble sulfates in the saline soil, defects are generated in the concrete in the tunnel, resulting in a decrease in strength and easy damage, and further leading to a reduction in the service life of the water conveyance tunnel. Summary of the Invention

[0005] In order to reduce the damage caused by the corrosion of the concrete in the tunnel by erosive salt ions and extend the service life of the water conveyance tunnel, this application provides a lining construction technology for small-section tunnels.

[0006] The lining construction technology for small-section tunnels includes the following steps:

[0007] S1. After the inverted arch is excavated, the base is cleaned.

[0008] S2. Reinforced concrete is poured in the inverted arch.

[0009] S3. The steel bars of the arch and wall are tied and concrete is poured.

[0010] S4. After the concrete of the arch and wall reaches a certain strength, curing is carried out.

[0011] The arch wall concrete is composed of raw materials including the following parts by weight: 900 - 1200 parts of coarse aggregate, 600 - 800 parts of fine aggregate, 240 - 300 parts of cement, 60 - 100 parts of fly ash, 50 - 70 parts of mineral powder, 140 - 190 parts of water, 7 - 11 parts of water reducing agent, and 26 - 50 parts of shielding absorbent. The shielding absorbent includes konjac mannan, zirconium hydroxide modified chitosan, and a flocculation component. The weight ratio of konjac mannan, zirconium hydroxide modified chitosan, and the flocculation component is (15 - 25):(2 - 4):10.

[0012] By adopting the above technical solution, konjac mannan forms a protective layer at the contact between the concrete and the inner wall of the tunnel. Zirconium hydroxide modified chitosan consumes sulfate ions, and the flocculation component causes the zirconium hydroxide modified chitosan combined with sulfate ions to accumulate. On the one hand, it enhances the strength of the protective layer, and on the other hand, as the node of the protective layer, it more attracts sulfate ions to move towards the direction close to zirconium hydroxide modified chitosan, thereby effectively reducing the sulfate ions penetrating into the concrete and reducing the damage caused by the corrosion of the concrete in the tunnel by erosive salt ions, and prolonging the service life of the water conveyance tunnel.

[0013] Preferably, the flocculation component includes polyaluminum chloride and polyacrylamide, and the weight ratio of polyaluminum chloride to polyacrylamide is 1:1.

[0014] By adopting the above technical solution, polyaluminum chloride and polyacrylamide are used in combination, thereby effectively improving the flocculation and accumulation effect of the flocculation component on zirconium hydroxide modified chitosan, and further making the node for consuming sulfate ions more prominent and more convenient for consuming sulfate ions.

[0015] Preferably, the preparation method of the zirconium hydroxide modified chitosan includes the following steps: Mix carbon tetrachloride, petroleum ether, and span 80, add a chitosan - acetic acid aqueous solution thereto, stir until the chitosan - acetic acid aqueous solution forms bead - like drops, add sodium hydroxide solution to adjust the pH = 8, then add zirconium hydroxide powder, add glutaraldehyde solution and continue to stir until gelation occurs, raise the temperature for reaction until the bead - like drops are solidified, then filter and wash with water until neutral, and perform drying to obtain zirconium hydroxide modified chitosan.

[0016] By adopting the above technical solution, after adding sodium hydroxide to neutralize acetic acid in the chitosan - acetic acid aqueous solution, zirconium hydroxide powder is added, thereby doping zirconium hydroxide on chitosan to form calcium hydroxide modified chitosan. Using chitosan as a carrier makes zirconium hydroxide easier to be aggregated by the flocculation component and concentrated, and it is easier to combine with sulfate ions after forming nodes.

[0017] Preferably, the drying method of the zirconium hydroxide modified chitosan is vacuum drying.

[0018] By adopting the above technical solution, the zirconium hydroxide modified chitosan particles obtained by vacuum drying have better performance and uniform particle size, and are easier to stir and disperse.

[0019] Preferably, it further includes 10-20 parts of waterborne polyurethane.

[0020] By adopting the above technical solution, using waterborne polyurethane as the enhancer of the protective layer enables the density of the protective layer between the concrete and the tunnel to be improved, further reducing the sulfate ions penetrating into the concrete.

[0021] Preferably, the weight ratio of the waterborne polyurethane to the zirconium hydroxide modified chitosan is 5:1.

[0022] By adopting the above technical solution, the waterborne polyurethane effectively improves the stability of the zirconium hydroxide modified chitosan. When the waterborne polyurethane improves the density of the protective layer, the sulfate ions are more likely to go to the nodes to react with the zirconium hydroxide modified chitosan, thereby further improving the sulfate ion erosion resistance of the concrete.

[0023] Preferably, the arch wall concrete is composed of the following raw materials in parts by weight: 1050 parts of coarse aggregate, 700 parts of fine aggregate, 270 parts of cement, 80 parts of fly ash, 60 parts of mineral powder, 165 parts of water, 9 parts of water reducing agent, 20 parts of konjac mannan, 3 parts of zirconium hydroxide modified chitosan, 5 parts of polyaluminum chloride, 5 parts of polyacrylamide, and 15 parts of waterborne polyurethane.

[0024] By adopting the above technical solution, the addition amounts of the raw materials are further limited, so that the ratio is more accurate and the sulfate ion erosion resistance of the concrete is further improved.

[0025] Preferably, the preparation method of the arch wall concrete includes the following steps: mixing the coarse aggregate, fine aggregate, cement, fly ash, and mineral powder, then adding water and water reducing agent and mixing, and finally adding konjac mannan, zirconium hydroxide modified chitosan, and the flocculation component as the shielding absorbent and mixing evenly.

[0026] By adopting the above technical solution, the raw materials are added in batches. After the initial mixing of the concrete, konjac mannan, zirconium hydroxide modified chitosan, and the flocculation component are added to prepare the concrete, and the operation is simple and convenient.

[0027] In summary, the present application has the following beneficial effects:

[0028] 1. Since the concrete provided by the present application is used in the lining construction process in the present application, the damage caused by the corrosion of the concrete in the tunnel by erosive salt ions is effectively reduced, and the service life of the water conveyance tunnel is extended.

[0029] 2. In this application, konjac glucomannan forms a protective layer at the contact between the concrete and the inner wall of the tunnel. Zirconium hydroxide modified chitosan consumes sulfate ions, and the flocculating component causes the zirconium hydroxide modified chitosan combined with sulfate ions to accumulate. On the one hand, it enhances the strength of the protective layer, and on the other hand, as the node of the protective layer, it attracts sulfate ions to move more towards the direction close to the zirconium hydroxide modified chitosan, thereby effectively reducing the sulfate ions penetrating into the concrete, reducing the damage caused by the corrosion of the concrete in the tunnel by erosive salt ions, and prolonging the service life of the water conveyance tunnel.

[0030] 3. In this application, waterborne polyurethane enhances the protective layer on the side of the concrete close to the tunnel, improves its density, and through the improvement of the density of the protective layer, it makes sulfate ions easier to go to the node to be combined and consumed by zirconium hydroxide modified chitosan, further reducing the sulfate ions penetrating into the concrete. Specific Embodiments

[0031] In this application, the coarse aggregate is gravel with a particle size of 5 - 50 mm; the fine aggregate is sand with a particle size of 0 - 5 mm; the cement is P.Ⅱ 42.5 Portland cement; the fineness of fly ash is 325 mesh; the mineral powder is S95 mineral powder; the water is pure water; the water reducing agent is polycarboxylate water reducing agent; the fineness of konjac glucomannan is 80 mesh; zirconium hydroxide is in powder form with a purity of 99.95%; polyaluminum chloride is solid particles with a fineness of 60 mesh; polyacrylamide is in powder form with a fineness of 600 mesh.

[0032] The following further elaborates on this application with reference to examples.

[0033] Preparation Examples

[0034] Preparation of zirconium hydroxide modified chitosan:

[0035] S1. Prepare an aqueous solution of chitosan acetate: Weigh chitosan and dissolve it in an aqueous acetic acid solution with a volume fraction of 2% to prepare an aqueous solution of chitosan acetate with a mass fraction of 2%.

[0036] S2. Take 3 L of carbon tetrachloride, 3 L of petroleum ether and 6 L of Span 80, then add 6 L of the aqueous solution of chitosan acetate in S1 above and add 300 g of zirconium hydroxide powder, and stir until the chitosan - acetic acid aqueous solution forms bead - like drops.

[0037] S3. Dropwise add sodium hydroxide solution to adjust the pH = 8, dropwise add 50 mL of glutaraldehyde solution with a volume fraction of 50% and then continue stirring until gelation occurs, heat up to 50 °C and react until the bead - like drops solidify, then filter and wash with water until neutral, and finally extract with acetone and vacuum dry to obtain zirconium hydroxide modified chitosan.

[0038] Examples

[0039] Example 1

[0040] The construction technology of the lining for small-section tunnels includes the following steps:

[0041] S1. After the invert excavation, install a temporary invert trestle to clean the base;

[0042] S2. Pour reinforced concrete in the invert;

[0043] S3. Bind the steel bars of the arch wall and pour concrete;

[0044] S4. Carry out maintenance after the arch wall concrete reaches a certain strength.

[0045] Example 2

[0046] The arch wall concrete for the construction of the lining of a small-end face tunnel is prepared by the following steps:

[0047] Mix 900 kg of coarse aggregate, 600 kg of fine aggregate, 240 kg of cement, 60 kg of fly ash and 50 kg of mineral powder evenly, then add 140 kg of water and 7 kg of water reducer and mix evenly, and finally add 15 kg of konjac mannan, 1 kg of zirconium hydroxide modified chitosan, 5 kg of polyaluminum chloride and 5 kg of polyacrylamide and mix to obtain the concrete.

[0048] Example 3

[0049] Mix 1050 kg of coarse aggregate, 700 kg of fine aggregate, 270 kg of cement, 80 kg of fly ash and 60 kg of mineral powder evenly, then add 165 kg of water and 9 kg of water reducer and mix evenly, and finally add 20 kg of konjac mannan, 1 kg of zirconium hydroxide modified chitosan, 5 kg of polyaluminum chloride and 5 kg of polyacrylamide and mix to obtain the concrete.

[0050] Example 4

[0051] The difference from Example 3 is that the addition amount of konjac mannan is 15 kg and the addition amount of zirconium hydroxide modified chitosan is 3 kg.

[0052] Example 5

[0053] The difference from Example 5 is that the addition amount of zirconium hydroxide modified chitosan is 3 kg.

[0054] Example 6

[0055] The difference from Example 3 is that the addition amount of konjac mannan is 25 kg and the addition amount of zirconium hydroxide modified chitosan is 3 kg.

[0056] Example 7

[0057] The difference from Example 3 is that the addition amount of zirconium hydroxide modified chitosan is 5 kg.

[0058] Example 8

[0059] The difference from Example 5 is that the addition amount of polyaluminum chloride is 10 kg and the addition amount of polyacrylamide is 0.

[0060] Example 9

[0061] The difference from Example 5 is that the addition amount of polyaluminum chloride is 0 and the addition amount of polyacrylamide is 10 kg.

[0062] Example 10

[0063] The difference from Example 5 is that 10 kg of waterborne polyurethane is further added.

[0064] Example 11

[0065] The difference from Example 10 is that the addition amount of waterborne polyurethane is 15 kg.

[0066] Example 12

[0067] The difference from Example 11 is that the addition amount of waterborne polyurethane is 20 kg.

[0068] Example 13

[0069] 1200 kg of coarse aggregate, 800 kg of fine aggregate, 300 kg of cement, 100 kg of fly ash and 70 kg of mineral powder are stirred and mixed evenly, then 190 kg of water and 9 kg of water reducing agent are added and stirred and mixed evenly, and finally 25 kg of konjac glucomannan, 5 kg of zirconium hydroxide modified chitosan, 5 kg of polyaluminum chloride and 5 kg of polyacrylamide are added and stirred and mixed to obtain concrete.

[0070] Comparative Example

[0071] Comparative Example 1

[0072] The difference from Example 5 is that polyaluminum chloride and polyacrylamide are not added.

[0073] Comparative Example 2

[0074] The difference from Example 5 is that zirconium hydroxide modified chitosan is not added.

[0075] Comparative Example 3

[0076] The difference from Example 5 is that konjac glucomannan is not added.

[0077] Comparative Example 4

[0078] The difference from Example 5 is that zirconium hydroxide modified chitosan, polyaluminum chloride and polyacrylamide are not added.

[0079] Comparative Example 5

[0080] The difference from Example 5 is that konjac mannan, polyaluminum chloride, and polyacrylamide were not added.

[0081] Comparative Example 6

[0082] The difference from Example 5 is that konjac mannan and zirconium hydroxide-modified chitosan were not added.

[0083] Comparative Example 7

[0084] The difference from Example 5 is that konjac mannan, zirconium hydroxide-modified chitosan, polyaluminum chloride, and polyacrylamide were not added.

[0085] Table 1 Raw material table of examples and comparative examples (kg)

[0086]

[0087]

[0088] Performance detection test

[0089] The properties of the concrete were detected according to the "Standard for Test Methods of Physical and Mechanical Properties of Concrete" GB / T 50081-2019. The detection items are as follows:

[0090] The properties of the concrete were detected according to the "Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete" GB / T 50082-2009. The detection items are as follows:

[0091] 14 Sulfate attack resistance test, 90 wet-dry cycles were set, and at the same time, a comparison specimen was set. According to the 5 compressive strength test, the cube compressive strength of the concrete was tested, and the corrosion resistance coefficient of the concrete compressive strength was calculated.

[0092] Table 2 Performance detection data table of examples and comparative examples

[0093]

[0094]

[0095] Combined with Example 5 and Comparative Examples 1-7 and Table 2, it can be seen that konjac glucomannan forms a protective layer at the contact between the concrete and the inner wall of the tunnel. Zirconium hydroxide-modified chitosan consumes sulfate ions, and the flocculation component causes the zirconium hydroxide-modified chitosan combined with sulfate ions to accumulate. On the one hand, it enhances the strength of the protective layer, and on the other hand, as the node of the protective layer, it attracts sulfate ions to move more towards the direction close to the zirconium hydroxide-modified chitosan, thereby effectively reducing the sulfate ions penetrating into the concrete, reducing the damage caused by the corrosion of the concrete in the tunnel by erosive salt ions, and prolonging the service life of the water conveyance tunnel.

[0096] Combined with Example 5, Example 10, Example 11 and Example 12 and Table 2, it can be seen that using waterborne polyurethane as the enhancer of the protective layer can improve the density of the protective layer between the concrete and the tunnel, further reducing the sulfate ions penetrating into the concrete; waterborne polyurethane effectively improves the stability of zirconium hydroxide-modified chitosan. Under the condition that waterborne polyurethane improves the density of the protective layer, sulfate ions are more likely to go to the node to react with zirconium hydroxide-modified chitosan, thereby further improving the sulfate ion erosion resistance of the concrete.

[0097] Combined with Example 5, Example 8 and Example 9 and Table 2, it can be seen that the combined use of polyaluminum chloride and polyacrylamide effectively improves the flocculation and accumulation effect of the flocculation component on zirconium hydroxide-modified chitosan, and further makes the node for consuming sulfate ions more prominent, making it more convenient to consume sulfate ions.

[0098] This specific embodiment is only an interpretation of the present application, and it is not a limitation of the present application. Those skilled in the art can make modifications without creative contributions to this embodiment according to needs after reading this specification, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. Construction technology for lining of small-section tunnel, characterized in that It includes the following steps: S1. After the invert excavation, clean the base; S2. Pour reinforced concrete into the invert; S3. Bind the steel bars of the arch wall and pour concrete; S4. Cure after the arch wall concrete reaches a certain strength; The arch wall concrete is composed of the following raw materials in parts by weight: 900 - 1200 parts of coarse aggregate, 600 - 800 parts of fine aggregate, 240 - 300 parts of cement, 60 - 100 parts of fly ash, 50 - 70 parts of mineral powder, 140 - 190 parts of water, 7 - 11 parts of water reducing agent, 26 - 50 parts of shielding absorbent. The shielding absorbent includes konjac glucomannan, zirconium hydroxide modified chitosan and flocculation component. The weight ratio of konjac glucomannan, zirconium hydroxide modified chitosan and flocculation component is (15 - 25):(2 - 4):

10. The preparation method of the zirconium hydroxide modified chitosan includes the following steps: Mix carbon tetrachloride, petroleum ether and span 80, add chitosan - acetic acid aqueous solution to it, stir until the chitosan - acetic acid aqueous solution is in the form of beads, add sodium hydroxide solution to adjust the pH = 8, then add zirconium hydroxide powder, add glutaraldehyde solution and continue to stir until gelation occurs, raise the temperature to react until the beads are solidified, then filter and wash with water until neutral, and dry to obtain zirconium hydroxide modified chitosan; The flocculation component includes polyaluminum chloride and polyacrylamide.

2. According to the small - section tunnel lining construction process described in claim 1, the weight ratio of polyaluminum chloride and polyacrylamide is 1:

1.

3. The construction technology of the lining for small-section tunnels according to claim 1 is characterized in that: The drying method of the zirconium hydroxide modified chitosan is vacuum drying.

4. The construction technology of the lining of a small-section tunnel according to claim 1, characterized in that: It also includes 10 - 20 parts of water - borne polyurethane.

5. The construction technology of the lining for small-section tunnel according to claim 4, characterized in that: The weight ratio of the water - borne polyurethane to the zirconium hydroxide modified chitosan is 5:

1.

6. The construction process of the lining of a small-section tunnel according to claim 4, characterized in that: The arch wall concrete is composed of the following raw materials in parts by weight: 1050 parts of coarse aggregate, 700 parts of fine aggregate, 270 parts of cement, 80 parts of fly ash, 60 parts of mineral powder, 165 parts of water, 9 parts of water reducing agent, 20 parts of konjac glucomannan, 3 parts of zirconium hydroxide modified chitosan, 5 parts of polyaluminum chloride, 5 parts of polyacrylamide, 15 parts of water - borne polyurethane.

7. The construction process of the lining for small-section tunnels according to claim 1, characterized in that: The preparation method of the arch wall concrete includes the following steps: Stir and mix the coarse aggregate, fine aggregate, cement, fly ash and mineral powder, then add water and water reducing agent and stir and mix, and finally add konjac glucomannan, zirconium hydroxide modified chitosan and flocculation component as the shielding absorbent and stir and mix evenly.

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