Research On Mechanical Properties And Application Of Nano-modified Shotcrete

Shotcrete has the advantages of economy,convenience,easy access to materials,and short setting time,and is widely used in tunnels and underground engineering.This results in a waste of engineering materials and seriously endangers the life and health of workers.At present,my country’s transportation construction has entered the14 th Five-Year Plan stage,and the development of green transportation infrastructure has become a new direction.Therefore,higher requirements are placed on the performance of shotcrete.As an emerging technology developed at the end of the twentieth century,nanotechnology can improve the internal structure of concrete through its nanoscale properties,providing a direction for the development of high-performance concrete.In this paper,relying on the Wangjiawuji tunnel project of the G4216 line along the Yangtze River Expressway,the mechanical properties and engineering application of the new nano-material modified shotcrete are studied by the combination of laboratory test,numerical simulation and field measurement.The main work and achievements of the paper are as follows:(1)The cubic compressive strength and the slump and expansion of the sprayed concrete under different proportions were measured by the method of laboratory test,and the mechanical properties and mixture properties of the sprayed concrete mixed with the new nanomaterials were improved.The performance of nanomaterials was evaluated,and the modification mechanism of new nanomaterials was discussed based on the existing research;(2)The nano-modified concrete meso-random aggregate model was established through the secondary development of numerical simulation software,and the meso-scale calculation parameters were obtained according to the above test results.The influence of tensile strength and damage and failure,and based on the conclusions obtained from the above studies,the axial compression constitutive of the shotcrete mixed with the new nanomaterials was fitted.(3)Based on the nano-sprayed concrete constitutive obtained from the above(4)research,four working conditions were designed by means of numerical simulation.The initial support parameters of nano-sprayed concrete are discussed.(5)Relying on Wangjiawuji Tunnel,research on the initial support field application of nano shotcrete,the main research contents include on-site inspection of ordinary shotcrete and nano-modified concrete initial support working state,on-site rebound rate measurement,application Effect and project cost comparison.