Abstract:

The model test and numerical simulation are adopted to study the variation rule of earth pressure of rectangular and arched opencut tunnels with filling height. The results obtained include: (1) The tunnel crosssection form has a great influence on earth pressure, and the influence varies under different foundation stiffnesses. The vertical earth pressure on the top axis of opencut tunnel with arched crosssection is greater than that of opencut tunnel with rectangular crosssection. (2) The variations of conplane vertical earth pressures of arched opencut tunnel with rigid foundation and flexible foundation present a decreasinggentle trend and a decreasingincreasinggentle trend, respectively; and that of rectangular opencut tunnel presents an increasingdecreasinggentle trend. (3) Two arches are presented as the distribution forms of the conplane horizontal earth pressures of opencut tunnel with rigid foundation, while only one arch is appeared above the top of opencut tunnel with flexible foundation. (4) The soil displacements of rectangular and arched opencut tunnels with rigid foundation present a W shape and a dualV shape from the top to 0.6 times tunnel height, respectively; they present a V shape in the range of 0.6 to 3 times tunnel height, and no relative settlement occurs above 3 times tunnel height; the soil displacements of rectangular and arched opencut tunnels with flexible foundation present a V shape in the range of 0 to 3 times tunnel height, and no relative settlement occurs above 3 times tunnel height.

Key words: highfilled opencut tunnel, tunnel crosssection form, difference law, earth pressure, displacement, foundation stiffness