Abstract:

The application of mechanicalcrushed sands concrete has some disadvantages, i.e. poor gradation, large fluctuation of performance indices, high rebound rate and low strength, etc. The equipment selection of processing system of mechanicalcrushed sands and its application to shotcrete and secondary lining of GuiyangGuangzhou Highspeed Railway Tunnel are studied by indoor and field experiments. The study results show that: 1) The mechanicalcrushed sand concrete with 40% of fly ash and 0.37 of waterbinder ratio can meet the requirements of relevant standards and design. 2) The working performance of concrete can be improved by increasing the amount of fly ash and reducing the water volume and waterbinder ratio when using shotcrete. 3) Appropriately reducing slump value to ensure shotcrete effect and solid quality can be chosen when the shotcrete process is mature at the construction site. 4) The mechanicalcrushed sand should not be too clean; and the physical, mechanical and durability properties of concrete can reach peak when the content of stone powder is 8%-12%.

Key words: tunnel engineering, mechanicalcrushed sands, secondary lining