对于潮汐、洪水、水库开闸降水等存在水位下降较快的地区,挡土墙稳定性设计越来越受到工程界的重视,但水位骤降条件下挡土墙墙前、墙后水位关系的研究还不够深入,稳定性影响规律也不够明了,挡土墙稳定性设计还存在许多安全隐患。以模型试验、数值模拟、理论研究相结合对某工程强透水地基箱型岸墙进行研究,结果表明:在不同降水速度、不同墙后填土渗透性下,挡土墙的稳定性先减小再增大,稳定性最差时刻发生在墙前水位处于3/5~3/4墙高,在各种条件下的最小抗倾和抗滑安全系数均比设计骤降工况计算得到的安全系数值大;影响挡土墙稳定性的关键因素是水土压力及墙体的有效重力的共同作用,并不一定是墙前、墙后水位差最大的时刻。

Many caisson walls are subjected to the sudden drawdown of water level in front of the structures due to tide, flood, and reservoir discharge, and the stability of caisson walls under such conditions has been an important issue in hydraulic and harbor engineering. However, present understanding on the relationship between stability and water level drawdown is still not clear, which causes some hidden safety issues in the design of such structures. In this study, this problem is investigated through model testing, numerical simulation and theoretical analysis. Two large-scale wall models were tested, based on which a numerical procedure was validated. The numerical procedure was then employed to analyze the pore water pressure in the backfill. The dynamic pore water pressure was finally used to analyze the stability of caisson walls on highly permeable foundations. It was found that the stability of the structure decreased and then increased with the drawdown of water level in the presence of varying discharging rate and backfill permeability, and the smallest factor of safety was found when the front water level was at 3/5-3/4 of the wall height. The minimum factors of safety against overturning and sliding in designed condition of rapid water level drawdown are larger than those under other conditions. Stability was largely under the combined effect of dynamic water pressure, earth pressure and the effective weight of the retaining wall, and the most unstable moment did not match the moment with the largest water level difference.