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Study on Earth Pressure Difference Law of Load Relieving Structure of the Rectangular and Arched High-filled Loess Open Cut Tunnels
(1 College of Civil Engineering, Lanzhou Institute of Technology, Lanzhou 730050; 2 College of Civil Engineering, Lanzhou Jiaotong University, Lanzhou 730070)
Abstract The high-filled open cut tunnel causes larger force applied on the structure and endangers its safety. Considering EPS induced load reduction, section type and foundation stiffness, the change rules of earth pressure and soil displacement on the top of open cut tunnel varying with the filling height are studied by model test and numerical simulation. The results show that the change of earth pressure on top of the load relieving structure of highfilled loess open cut tunnel is of nonlinear with filling height, the open cut tunnel with arched section is better than the rectangular one and the open cut tunnel with flexible foundation is better than that with rigid foundation regarding the load relieving effect; the earth pressure increases at first and decreases later and finally tends to be stable from the center at top to the two sides of open cut tunnel with rectangular section, the peak earth pressure occurs at the boundary of both sides of open cut tunnel, the difference between the peak earth pressure and the earth pressure at the central point of tunnel crown decreases due to the EPS induced load relieving and flexible foundation; the vertical earth pressure decreases at first and tends to be stable from the center to the two sides of open cut tunnel with arched section and the peak earth pressure occurs at the central point of tunnel top. The curve pattern of soil mass settlements at the top of the open cut tunnel with rectangle section changes from the "double V" before load relieving to the "U" distribution after load relieving. A numerical simulation analysis on the test process is conducted, and the average error of the two calculation results is 11.0%, which validates the correctness of the experiment data and the rationality of the calculation parameters. Finally the differences of soil arch effects of the load relieving structures of open cut tunnels with different section types and foundation stiffnesses are discussed in terms of lateral stress of fillings.
Abstract：
The high-filled open cut tunnel causes larger force applied on the structure and endangers its safety. Considering EPS induced load reduction, section type and foundation stiffness, the change rules of earth pressure and soil displacement on the top of open cut tunnel varying with the filling height are studied by model test and numerical simulation. The results show that the change of earth pressure on top of the load relieving structure of highfilled loess open cut tunnel is of nonlinear with filling height, the open cut tunnel with arched section is better than the rectangular one and the open cut tunnel with flexible foundation is better than that with rigid foundation regarding the load relieving effect; the earth pressure increases at first and decreases later and finally tends to be stable from the center at top to the two sides of open cut tunnel with rectangular section, the peak earth pressure occurs at the boundary of both sides of open cut tunnel, the difference between the peak earth pressure and the earth pressure at the central point of tunnel crown decreases due to the EPS induced load relieving and flexible foundation; the vertical earth pressure decreases at first and tends to be stable from the center to the two sides of open cut tunnel with arched section and the peak earth pressure occurs at the central point of tunnel top. The curve pattern of soil mass settlements at the top of the open cut tunnel with rectangle section changes from the "double V" before load relieving to the "U" distribution after load relieving. A numerical simulation analysis on the test process is conducted, and the average error of the two calculation results is 11.0%, which validates the correctness of the experiment data and the rationality of the calculation parameters. Finally the differences of soil arch effects of the load relieving structures of open cut tunnels with different section types and foundation stiffnesses are discussed in terms of lateral stress of fillings.
MA Li1 LI Sheng2 WANG Qicai2 YU Bentian2 LIU Yapeng2 WANG Qingshi2
.Study on Earth Pressure Difference Law of Load Relieving Structure of the Rectangular and Arched High-filled Loess Open Cut Tunnels[J] MODERN TUNNELLING TECHNOLOGY, 2019,V56(6): 63-69
2019, Vol. 56 