Cause Analysis and Research of Influence Factors of Cracks in Railway Tunnel Lining Concrete

Aiming at the cracking of railway tunnel lining concrete, the cracking reasons were analyzed, the non-load factor was determined as the main reason, and the main factors which affecting the shrinkage cracking of lining concrete were discussed in this paper. On this basis, the influences of binder content, unilateral water content, sand ratio and limestone powder content on cracking sensitivity of lining concrete were studied, by using dry-shrinkage, flexural strength and splitting tensile strength as the evaluation indexes of cracking sensitivity of concrete. The results show that the binder content has a significant effect on the dry-shrinkage of lining concrete, and the 56d dry-shrinkage value of concrete increases by about 8% with the increase of 20kg binder. The flexural strength and spitting tensile strength of lining concrete firstly increase and the decrease with the decrease of unilateral water content, and the unilateral water content should be controlled at about 140 kg/m3–145 kg/m3. The increase of sand ratio is unfavorable to the cracking sensitivity of lining concrete. The flexural strength and spitting tensile strength of lining concrete tend to decrease with the increase of limestone powder content, and the limestone powder content should be controlled within 20%.