Tunnel primary support sprayed concrete calcium ion curing anti-crystallization construction method

Abstract

The invention relates to a tunnel primary support sprayed concrete calcium ion curing anti-crystallization construction method, which comprises the following steps of: (1) looking up construction drawing geological exploration data, and pre-judging the water content condition of a tunnel site; (2) sampling surrounding rock fissure water: after the tunnel is excavated, arranging 1-2 sampling points at a water outlet part which has strand-shaped or continuous drop-shaped water outlet and is not polluted by primary support sprayed concrete on a fresh rock surface, and sampling the surrounding rock fissure water; (3) sending the surrounding rock fissure water to a professional detection mechanism for detection and issuing a detection report, and combining the detection report with a water quality test report in a design file for analysis to obtain ion concentration values of HCO3 <-> and SO4 < 2-> in the tunnel site area; (4) when the total ion concentration value is less than or equal to 150mg / L, performing according to a conventional preliminary bracing construction process; and when the total ion concentration value is greater than 150mg / L, implementing an anti-crystallization control measure. The method has the advantages of low construction cost, simplicity in construction and good anti-crystallization effect.

Description

Technical Field

[0001] The invention relates to the technical field of tunnel initial support shotcrete, and in particular to a tunnel initial support shotcrete calcium ion solidification and anti-crystallization construction method. Background Art

[0002] The problem of blockage and failure of the tunnel drainage system due to crystal deposition has become a major technical problem that plagues the tunnel engineering community. Water damage and other related problems caused by water damage during tunnel construction have caused great trouble to tunnel builders. If they are not well resolved during the construction period, they will also bring a huge workload to the subsequent operation and maintenance of the tunnel, and may even seriously endanger the driving safety of the tunnel.

[0003] At present, the relevant technologies for this problem focus on optimizing drainage structures and strengthening the cleaning of drainage systems in later stages. These methods have the problems of high construction costs and treating symptoms instead of the root causes. Therefore, in order to solve the problem of crystal deposition in tunnel drainage systems, which leads to drainage system failure and further damage to tunnel structures, a construction method that eliminates crystal deposition from the root is urgently needed to effectively solve this problem. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a tunnel initial support shotcrete calcium ion solidification anti-crystallization construction method with low cost, simple construction and good anti-crystallization effect.

[0005] In order to solve the above problems, a tunnel initial support shotcrete calcium ion solidification and anti-crystallization construction method described in the present invention comprises the following steps:

[0006] ⑴ Check the geological survey data of the construction drawings to predict the water content of the tunnel site;

[0007] ⑵Sampling of surrounding rock fissure water:

[0008] After tunnel excavation, set up 1-2 sampling points at the fresh rock surface where water is flowing out in strands or continuous drops and is not contaminated by the initial support shotcrete, and sample the surrounding rock fissure water;

[0009] (3) Send the surrounding rock fissure water to a professional testing agency for testing and issue a test report. Combined with the water quality test report in the design document, the HCO of the tunnel site area is obtained. 3 - and SO 4 2- The ion concentration value of

[0010] (4) Compare the ion concentration value measured in step (3) with Table 1:

[0011] Table 1 (HCO 3- +SO 4 2- ) Relationship between total ion concentration and tunnel crystallization grade

[0012]

[0013] When the total ion concentration value is ≤150mg / L, the conventional initial support construction process shall be followed; when the total ion concentration value is greater than 150mg / L, anti-crystallization control measures shall be implemented.

[0014] 2. A method for preventing crystallization of shotcrete calcium ion solidification in initial support of a tunnel as claimed in claim 1, characterized in that the anti-crystallization control measures in step (4) are implemented as follows:

[0015] ① Design and verify the mix ratio of anti-crystallization shotcrete:

[0016] 5% to 8% of powdered calcium ion curing agent is used as an admixture to replace twice the mass of cement in shotcrete, and the anti-crystallization shotcrete mix ratio of 5% and 8% of calcium ion curing agent is determined;

[0017] ② Mixing and transporting anti-crystallization shotcrete to the site;

[0018] ③ Anti-crystallization shotcrete construction.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] 1. The present invention clarifies the content of HCO in surrounding rock fissure water 3 - +SO 4 2- ) The relationship between the total amount of ion concentration and the crystallization grade of the tunnel is studied, and a new type of anti-crystallization shotcrete is formed by adding a new admixture - calcium ion curing agent into the initial support shotcrete, thereby curbing the crystallization reaction in the shotcrete and reducing the amount of calcium ion crystals on the initial support surface.

[0021] 2. The present invention complies with the principle of source prevention and proposes the best calcium ion curing agent blending ratio. Using 5% to 8% of powdered calcium ion curing agent as an admixture to replace twice the mass of cement in shotcrete can inhibit the formation of 60% to 80% of crystals. Figures 2-3 shown.

[0022] 3. After adding calcium ion curing agent to shotcrete, the rebound rate of shotcrete is reduced, the concrete loss is reduced, and the construction cost is low compared with the traditional solution of changing the drainage structure and increasing the number of drainage ditches. At the same time, the present invention only needs to add calcium ion additives during the concrete mixing process according to the determined relevant mix ratio, and other construction steps remain unchanged, so the construction is simple. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The specific implementation modes of the present invention are further described in detail below in conjunction with the accompanying drawings.

[0024] Figure 1 It is a flow chart of the present invention.

[0025] Figure 2 This is a diagram showing the effect of not adding a calcium ion curing agent in the present invention.

[0026] Figure 3 This is a diagram showing the effect of adding a calcium ion curing agent in the present invention. DETAILED DESCRIPTION

[0027] like Figure 1 As shown, a tunnel initial support shotcrete calcium ion solidification and anti-crystallization construction method comprises the following steps:

[0028] ⑴ Check the geological survey data of the construction drawings to predict the water content of the tunnel site.

[0029] Before construction, the "Tunnel Engineering Design Documents" and "Engineering Geological Survey Report" need to be carefully studied and analyzed in depth to clarify the design intent, especially the "Water Quality Analysis Test Report" in the water-rich tunnel, to predict the probability and severity of tunnel crystallization in advance.

[0030] ⑵Sampling of surrounding rock fissure water:

[0031] After tunnel excavation, 1 to 2 sampling points are set up on the fresh rock surface where water flows out in streams or continuous drips and is not contaminated by the initial support shotcrete, and sampling of surrounding rock fissure water is carried out.

[0032] Before collecting water samples, wash the sampling container, sample bottle and bottle stopper three times with the water sample at the sampling point, and then fill the sample bottle with water sample in batches through the sampling container. The volume of a single bottle of sampled water is 350ml, and the total volume cannot be less than 2000ml. After the sample is collected, the bottle mouth should be sealed immediately to prevent the water sample from being lost and impurities from entering the bottle, and the sampling record should be made after the sampling is completed.

[0033] (3) Send the surrounding rock fissure water to a professional testing agency for testing and issue a test report. Combined with the water quality test report in the design document, the HCO of the tunnel site area is obtained. 3 -and SO 4 2- The ion concentration value.

[0034] (4) Compare the ion concentration value measured in step (3) with Table 1:

[0035] Table 1 (HCO 3 - +SO 4 2- ) Relationship between total ion concentration and tunnel crystallization grade

[0036]

[0037] When the total ion concentration value is ≤150mg / L, the conventional initial support construction process shall be followed.

[0038] When the total ion concentration is greater than 150 mg / L, anti-crystallization control measures are implemented as follows:

[0039] ① Design and verify the mix ratio of anti-crystallization shotcrete;

[0040] 5% to 8% of powdered calcium ion curing agent is used as an admixture to replace twice the mass of cement in shotcrete, and the anti-crystallization shotcrete mix ratio of 5% and 8% calcium ion curing agent is determined. The calcium ion curing agent is the shotcrete calcium ion curing agent (CH-GH series) produced by Chengdu Yanghua Yuandong New Material Technology Co., Ltd.

[0041] According to Table 3, the mixing performance, mechanical properties, and long-term performance related indicators of anti-crystallization shotcrete were tested in the site laboratory. The concrete performance test indicators and implementation specifications should comply with Table 3 to determine the effects of calcium ion curing agent dosage of 5% and 8% on the main properties of shotcrete. After relevant tests, the shotcrete mix ratios of 5% and 8% calcium ion curing agent were determined, and the recommended mix ratios are shown in Table 2.

[0042] Table 2 Anti-crystallization shotcrete mix ratio

[0043]

[0044] Table 3 Anti-crystallization shotcrete performance index test table

[0045]

[0046] ② Mixing and transporting anti-crystallization shotcrete to the site:

[0047] Anti-crystallization shotcrete is mixed according to the construction mix ratio. The concrete is mixed by a fully automatic metering and batching forced mixer, and the mixer is regularly metered and calibrated. The order and method of feeding materials during wet spraying mixing should be correct. The mixing process is as follows: first add crushed stone, sand, cement and calcium ion curing agent and stir for 1 minute, then add appropriate amount of water (sand and stone moisture content is not more than 8%) and high-efficiency water reducing agent and stir for 1 minute. The mixed concrete has good workability and the slump meets the requirements before it can be used.

[0048] After the wet shotcrete is prepared, it should be transported to the working surface for spraying as soon as possible. During transportation, it should be stirred continuously to prevent segregation, water seepage, excessive reduction of slump, and even solidification. According to the distance from the mixing station to the tunnel working surface, a corresponding number of concrete transport tankers should be configured to ensure the continuous and uninterrupted supply of concrete during wet shotcrete operations. Shotcrete should be mixed as it is used. After the concrete is mixed, it is best to spray it within 30 minutes for better results.

[0049] ③ Anti-crystallization shotcrete construction:

[0050] The spraying of concrete should be carried out in sections, slices and layers. The spraying sequence should be from bottom to top, and the length of each section should not be greater than 6m. When spraying, first roughly level the low-lying areas, and then spray in layers and reciprocatingly from bottom to top.

[0051] The basic principle of spraying trolley operation is: rough spraying first, then leveling, spot spraying first, then spraying at the back, multi-layer spraying, cyclic spraying, large-displacement rough spraying for the bottom layer of concrete, small-displacement fine spraying for the outer layer of concrete, until the spraying surface is smooth and flat, so as to maximize the spraying of concrete mixture on the rock surface with the minimum rebound to form a compact, dense, and solidified bonding layer. During concrete spraying operations, the spraying distance, angle, spraying sequence, and nozzle movement have a great impact on the quality and rebound of the sprayed concrete, and the process details need to be strengthened. Process control.

Claims

1. A tunnel initial support shotcrete calcium ion solidification anti-crystallization construction method, comprising the following steps: ⑴ Check the geological survey data of the construction drawings to predict the water content of the tunnel site; ⑵Sampling of surrounding rock fissure water: After tunnel excavation, set up 1-2 sampling points at the fresh rock surface where water is flowing out in strands or continuous drops and is not contaminated by the initial support shotcrete, and sample the surrounding rock fissure water; ⑶ Send the surrounding rock fissure water to a professional testing agency for testing and issue a test report. Combined with the water quality test report in the design document, the HCO3 - and SO4 2- The ion concentration value of (4) Compare the ion concentration value measured in step (3) with Table 1: Table 1 (HCO3 - +SO4 2- ) Relationship between total ion concentration and tunnel crystallization grade When the total ion concentration value is ≤150mg / L, the conventional initial support construction process shall be followed; when the total ion concentration value is greater than 150mg / L, anti-crystallization control measures shall be implemented.

2. A tunnel initial support shotcrete calcium ion solidification and anti-crystallization construction method as claimed in claim 1, characterized in that: The anti-crystallization control measures in step (4) are implemented as follows: ① Design and verify the mix ratio of anti-crystallization shotcrete: 5% to 8% of powdered calcium ion curing agent is used as an admixture to replace twice the mass of cement in shotcrete, and the anti-crystallization shotcrete mix ratio of 5% and 8% of calcium ion curing agent is determined; ② Mixing and transporting anti-crystallization shotcrete to the site; ③ Anti-crystallization shotcrete construction.

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