Abstract:

The production of mechanicalcrushed sands faces two problems, i.e., interrupted gradation and environmental pollution. In the production of the mechanicalcrushed sands for Tianping tunnel on ChongqingGuiyang railway, FG500 spiral sand washing machines, circuitous water filter cartridges and pressured filter equipment with multiphased electrical switches and intermitted operation functions are installed, so as to recover the sands with particle size ranging from 0.075 mm to 0.15 mm, and in turn to compensate the missing grades of the sands. Furthermore, trial concrete mixing is made to verify the study results, which shows that the gradation of the mechanicalcrushed sands is one of the key factors that have influence on the performance of the mechanicalcrushed sands. Besides this, filtering equipment is 〖HQK〗installed to separate the stone fumes with particle size being less than 0.075 mm from the water, so as to prevent the environment from being polluted by water released in the production of the mechanicalcrushed sands. Conclusion is drawn that these key technologies should be well implemented in the production so as to achieve a good coordination among technology, economy and environment protection.

Key words: railway tunnel, mechanicalcrushed sand, gradation curve, fineness modulus, mechanicalcrushed sand concrete (MSC), environment and water conservation, economy