Abstract Support failure and tunnel collapse often occur during construction of loess tunnels. Based on the moni?
toring and measurement data of railway loess tunnels, a statistical analysis on the deformation laws of loess tunnels with different surrounding rock grades, buried depths and moisture contents were studied, with the results showing that: (1) the values of crown settlements and peripheral convergence of the loess tunnel in surrounding rock of grade Ⅳ are almost within 50 mm and 35 mm respectively, while the values of crown settlements and peripheral convergence of the loess tunnel in surrounding rock of grade Ⅳ are almost within 60 mm and 40 mm respectively; (2) the crown settlement and convergence of double-track loess tunnels in surrounding rock of grade Ⅳ and Ⅴ have a positive relationship with moisture content, deformation rate increases at first and then decreases, and deformation increases obviously when water content exceeds 16%; (3) based on the statistics of crown settlements, it proposed that the range of reserved deformation of loess tunnels in surrounding rock of grade Ⅳ and Ⅴ should be 7-9 cm and 12-15 cm respectively; (4) the key points of construction management of loess tunnels include identification of key and difficult works, strict construction scheme review before commencement, paying attention to ground surface treatment, enhancing geological forecast, monitoring and measurement during tunnel construction, strict management of the design alteration, construction process and quality .
Abstract：
Support failure and tunnel collapse often occur during construction of loess tunnels. Based on the moni?
toring and measurement data of railway loess tunnels, a statistical analysis on the deformation laws of loess tunnels with different surrounding rock grades, buried depths and moisture contents were studied, with the results showing that: (1) the values of crown settlements and peripheral convergence of the loess tunnel in surrounding rock of grade Ⅳ are almost within 50 mm and 35 mm respectively, while the values of crown settlements and peripheral convergence of the loess tunnel in surrounding rock of grade Ⅳ are almost within 60 mm and 40 mm respectively; (2) the crown settlement and convergence of double-track loess tunnels in surrounding rock of grade Ⅳ and Ⅴ have a positive relationship with moisture content, deformation rate increases at first and then decreases, and deformation increases obviously when water content exceeds 16%; (3) based on the statistics of crown settlements, it proposed that the range of reserved deformation of loess tunnels in surrounding rock of grade Ⅳ and Ⅴ should be 7-9 cm and 12-15 cm respectively; (4) the key points of construction management of loess tunnels include identification of key and difficult works, strict construction scheme review before commencement, paying attention to ground surface treatment, enhancing geological forecast, monitoring and measurement during tunnel construction, strict management of the design alteration, construction process and quality .
KONG Qingxiang
.Study on Deformation Law and Key Points of Construction Management of
Loess Tunnels[J] MODERN TUNNELLING TECHNOLOGY, 2019,V56(2): 18-23
2019, Vol. 56 