Coulomb模型下考虑墙体侧向位移的土压力计算

Relationship between earth pressure and wall displacement based on Coulomb earth pressure model

墙体侧向位移对土压力有显著影响。基于墙体位移–土压力关系是墙后土体应力应变特征的宏观体现这一基本认识,通过构建Coulomb土压力模型下的几何与平衡方程,将直剪试验中微观的土体单位长度剪切位移ε同剪应力τ关系转化成宏观上的墙体位移与土压力曲线,推导了极限位移可求、涵盖主动至被动状态全过程的墙体位移–土压力计算模型。分析表明：滑移区范围、初始应力状态及土体的ε–τ关系是影响墙体位移–土压力曲线的核心要素;相对于主动区,被动区范围对墙土摩擦作用更加敏感,导致静止与被动状态之间的位移–土压力关系受墙土摩擦影响更加显著;墙后土体初始应力状态对墙体位移的影响主要体现为静止土压力系数K_0,随着K_0的增大主动与被动状态下的墙体位移相应增加和减小;极限状态下墙体位移与工程经验吻合,理论模型能基本反映土压力随位移的变化规律。

The magnitude of earth pressure is greatly influenced by wall displacement. Based on the viewpoint that the relationship between wall displacement and lateral earth pressure is the macroscopic embodiment of soil stress-strain behavior, the relationship between soil shear displacement and shear stress is transformed into the wall displacement-earth pressure curve by using the geometric and equilibrium equation. The analysis indicates that the wall displacement-lateral earth pressure curve is primarily governed by the active or passive zones, initial stress state of retaining soil mass and soil stress-strain behavior. The passive zone is more easily changed with the interface friction angle compared with the active one, making that the wall displacement-lateral curve from the initial state to the passive state is affected by the interface friction angle more significantly. The influence of initial earth pressure state lies in the lateral pressure coefficient K0 at rest, and the required wall displacement reaching the active state tends to grow with the increase of K0, while the required displacement reaching the passive state tends to decline. Reasonable agreement between the results of model tests and the predicted values using the proposed method shows that the solution can provide accurate relationship between lateral earth pressures and wall displacement.