Shuiwen dizhi gongcheng dizhi (Jul 2021)
The earth pressure of retaining wall with cohesive fill based on principal stress rotation
Abstract
The soil behind a wall is in a stress state with self-weight stress and horizontal stress as the main stress for the Rankine retaining wall with horizontal fill. However, there is a certain wall-soil friction and bonding force in practice. The friction and bonding force may cause the principal stress deflection in the fill near the retaining wall, and the classical Rankine earth pressure theory is not applicable for this case. In the current study, the principal stress deflection of the fill near the retaining wall is processed both by the rotation and by the analysis of the stress from the Mohr circle in the fill behind the wall. The active and passive earth pressures of the retaining wall filled with the cohesive soil is derived, considering the wall-soil friction and bonding force. The influences of the fill friction angle and the wall-soil friction angle on the earth pressures are analyzed. The examples are further used to compare the results from this study with those with the improved Coulomb method. The results show that the Rankine earth pressure is a special case of the formula presented in this study. With the increase of the wall-soil friction angle and internal friction angle, the passive earth pressures gradually increase. The active earth pressures decrease with the increase of the internal friction angle, and the decreasing rate gradually decreases. When the internal friction angle is small, the active earth pressures decrease continuously with the increase of the wall-soil friction angle, and the decreasing speed gradually decreases. When the internal friction angle is large, the active earth pressures first decrease and then increase with the increase of the wall-soil friction angle. The effect of the fill friction angle is more obvious than that of the wall-soil friction angle. Compared with the results from other methods, the active earth pressures obtained with this method are larger, but the passive earth pressure is smaller, and their differences increase with the increase in the wall-soil friction, especially when the cohesion is considered. Because the deflection of the principal stress in the soil on the back of the wall is more consistent with the actual situations, the results from this study will be more suitable to compute the earth pressure in practice.
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