High-strength and quick-hardening shotcrete and soft-rock tunnel surrounding rock closing and strengthening method

Abstract

The invention discloses high-strength and quick-hardening shotcrete and a soft-rock tunnel surrounding rock closing and strengthening method. The high-strength and quick-hardening shotcrete compriseswater, cement, fly ash, gravel and sand, wherein the weight ratio of the fly ash to the cement is 0.92:0.08, the ratio of the weight of water to the total weight of the cement and the fly ash is (0.35-0.45):1, the ratio of the weight of the gravel and the total weight of the cement and the fly ash is (1.35-1.4):1, and the ratio of the weight of the sand and the total weight of the cement and the fly ash is 2.02:1. The high-strength and quick-hardening shotcrete is high in setting speed, can achieve initial setting within 35min plus or minus 5min, has the cubic average compressive strength being higher than or equal to 20MPa at 4h, has the cubic average compressive strength being higher than or equal to 30MPa at 24h, can timely and quickly close and strengthen an excavated surface, and hashigh early strength. In tunnel construction, the high-strength and quick-hardening shotcrete is sprayed first and then ordinary shotcrete is sprayed, so that effective connection of the low-age strength and the high-age strength of the shotcrete is achieved, and optimization of the functionality and the economy of the shotcrete is achieved.

Description

technical field [0001] The invention relates to a concrete used for sealing and reinforcing surrounding rocks in soft rock tunnel construction, and belongs to the technical field of application of concrete materials such as tunnel engineering, slope engineering, and mining engineering. Background technique [0002] my country is already the country with the largest tunnel project scale, the largest number and the fastest construction speed in the world. As of the end of 2017, 14,040km / 15,181 road tunnels have been built, and 15,781km / 14,700 railway tunnels have been built by the end of 2017. By 2020, my country's high-speed railways will have a mileage of 30,000 kilometers (the existing 22,000 kilometers). Kilometers; 150,000 kilometers of highways will be built (the existing 131,000 kilometers), and 19,000 kilometers will need to be added. In addition, the transportation development in the central and western regions has obvious shortcomings and is relatively lagging behind...

AI Technical Summary

Problems solved by technology

[0005] (1) The condensation speed is slow and the hysteresis is obvious, which cannot provide bearing and reinforcement in time, and even increases the self-weight of the structure

[0006] (2) The early strength is low, which cannot meet the conditions of the tunnel construction process, and cannot exert the early strength support function, and the support effect is not ideal

[0007] (3) The flexibility is poor, and the accelerator with strong alkali is mixed, which seriously affects the later strength of the sprayed concrete, resulting in the cracking and falling of the sprayed layer.

[0008] (4) The amount of rebound is large, and the cohesion of ordinary silicate sprayed concrete is poor, the amount of rebound is large during the spraying process, and the waste of concrete materials is serious

[0009] (5) The durability is poor, and too many external admixtures are added to the concrete, such as common water reducers, retarders, accelerators, etc., which have a great impact on the durability of shotcrete

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