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Analysis on the Construction Hazard Causes of Tunnels with Altitude Difference in the Tilted Soft-hard Interbedded Stratum
(1. State Key Laboratory of Mountain Bridge and Tunnel Engineering, Chongqing Jiaotong University, Chongqing 400074;2.School of Civil Engineering, Chongqing Jiaotong University, Chongqing 400074; 3.Xinjiang Communications Construction Group Co.,Ltd., Urumqi 830016)
Abstract To solve the construction hazards of tunnels with altitude difference under construction in Guizhou, such as large deformation of surrounding rock and lining cracks, field investigation and numerical simulation are used to research the mechanical response to tunnel construction in the tilted soft-hard interbedded stratum and its hazard causes, and the treatment methods are put forward. The results show that the main geological factors causing tunnel cracking include soft-hard interbedded stratum and topographical changes. Cracking in the crown area is more affected by tilted soft-hard interbedded strata, and the extent of damage to the invert area is more affected by the construction of subsequent driving tunnel; from the steep area at the entrance to the flat area at the exit, the stress and displacement of advanced tunnel are gradually reduced, and the maximum differences are 4.34 MPa and 38.89 mm,respectively. The lining cracking of the advanced tunnel occurs on the left side of the crown, on the left shoulder and at the backfilling of the invert, and the subsequent driving tunnel separately increases the stress on these three locations by 29.84%, 54.58% and 130.61%; the high-gradient tilted strata increase the shear slip between rock formations so that the tunnel deflects to the bottom right, and if the absolute displacement is too large, it will cause uneven deformation of various locations, resulting in asymmetric damage to the tunnel structure; attention should be paid to the following problems during the tunnel construction in a tilted soft-hard interbedded stratum: insufficient bearing capacity of the advanced tunnel base, large deformation of surrounding rock, etc., and the methods, such as full-face grouting, temporary invert and root piles made of steel tubes, can effectively prevent cracking.
Abstract：
To solve the construction hazards of tunnels with altitude difference under construction in Guizhou, such as large deformation of surrounding rock and lining cracks, field investigation and numerical simulation are used to research the mechanical response to tunnel construction in the tilted soft-hard interbedded stratum and its hazard causes, and the treatment methods are put forward. The results show that the main geological factors causing tunnel cracking include soft-hard interbedded stratum and topographical changes. Cracking in the crown area is more affected by tilted soft-hard interbedded strata, and the extent of damage to the invert area is more affected by the construction of subsequent driving tunnel; from the steep area at the entrance to the flat area at the exit, the stress and displacement of advanced tunnel are gradually reduced, and the maximum differences are 4.34 MPa and 38.89 mm,respectively. The lining cracking of the advanced tunnel occurs on the left side of the crown, on the left shoulder and at the backfilling of the invert, and the subsequent driving tunnel separately increases the stress on these three locations by 29.84%, 54.58% and 130.61%; the high-gradient tilted strata increase the shear slip between rock formations so that the tunnel deflects to the bottom right, and if the absolute displacement is too large, it will cause uneven deformation of various locations, resulting in asymmetric damage to the tunnel structure; attention should be paid to the following problems during the tunnel construction in a tilted soft-hard interbedded stratum: insufficient bearing capacity of the advanced tunnel base, large deformation of surrounding rock, etc., and the methods, such as full-face grouting, temporary invert and root piles made of steel tubes, can effectively prevent cracking.
LIU Zonghan1,
2 HAN Fenglei1,
2 ZHANG Xuefu1 etc
.Analysis on the Construction Hazard Causes of Tunnels with Altitude Difference in the Tilted Soft-hard Interbedded Stratum[J] MODERN TUNNELLING TECHNOLOGY, 2022,V59(6): 197-207
2022, Vol. 59 