A kind of high-strength and fast-hardening shotcrete and method for sealing and strengthening surrounding rock of soft rock tunnel

Abstract

The invention discloses a high-strength rapid-hardening shotcrete and a method for sealing and reinforcing the surrounding rock of a soft rock tunnel, wherein the high-strength rapid-hardening shotcrete includes water, cement, fly ash, gravel and sand; the weight of cement and fly ash The ratio is 0.92:0.08, the ratio of the weight of water to the total weight of cement and fly ash is (0.35~0.45):1, and the ratio of the weight of gravel to the total weight of cement and fly ash is (1.35~1.4): 1. The weight ratio of sand to the total weight of cement and fly ash is 2.02:1. The concrete of the present invention has a fast setting speed, and the sprayed concrete can be initially set in 35±5 minutes. The average compressive strength of the shotcrete 4h cube is ≥20MPa, and the average compressive strength of the 24h cube is ≥30MPa, which can timely and quickly seal and reinforce the excavation surface , high early strength. In the tunnel construction, the initial spraying of high-strength and fast-hardening shotcrete and the re-spraying of ordinary shotcrete make the "young" and "old" strengths of the shotcrete effectively connected, and realize the optimization of the functionality and economy of the shotcrete.

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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