Abstract Using the concept of protection by shield shell and flexibility of NATM for complex geology, large-sec?
tion excavation is possible under the protection of a pre-built arch using the mechanical pre-cutting method, which has obvious advantages in low-strength sand and soil strata approaching construction. Regarding the problem of difficult spraying and pouring of concrete in the slot, such special requirements as concrete strength and other properties are discussed based on an investigation and calculation analysis. It is concluded that the compressive strength of concrete in the slot after 8 hours should reach 12 MPa for a double-track loess tunnel with a large section; the traditional concrete spraying equipment needs to be improved, and the mixing ratio of concrete should be optimized and an indoor experiment for concrete in the slot should be compared with the coring test at the site.
Abstract：
Using the concept of protection by shield shell and flexibility of NATM for complex geology, large-sec?
tion excavation is possible under the protection of a pre-built arch using the mechanical pre-cutting method, which has obvious advantages in low-strength sand and soil strata approaching construction. Regarding the problem of difficult spraying and pouring of concrete in the slot, such special requirements as concrete strength and other properties are discussed based on an investigation and calculation analysis. It is concluded that the compressive strength of concrete in the slot after 8 hours should reach 12 MPa for a double-track loess tunnel with a large section; the traditional concrete spraying equipment needs to be improved, and the mixing ratio of concrete should be optimized and an indoor experiment for concrete in the slot should be compared with the coring test at the site.
HAN Gao-Sheng- 1 Wang-Xiu-Ying- 2 Wang-Bei-Hua- 2
.On Some Issues with Concrete during Tunnelling by the Mechanical PreCutting Method[J] MODERN TUNNELLING TECHNOLOGY, 2017,V54(1): 9-16
2017, Vol. 54 