饱和软土中深基坑主动土压力实测研究

Field testing study on active earth pressure of saturated soft clay in deep foundation pit

对饱和软黏土中11.0m的深基坑进行了主动土压力与深层位移监测。基坑竖向支护体采用钻孔灌注桩,水平向采用两道钢筋混凝土内支撑。实测主动土压力大于按照朗肯主动土压力公式的计算值,实测值约是计算值的1.20倍,阳角处的主动土压力实测值与计算值的比值大于正常位置的比值,约是正常处的1.13倍。实测主动土压力与墙后土体水平位移关系符合双曲线规律。达到主动土压力状态时,对应的墙后土体水平位移约为开挖深度的0.1%。

The monitoring of active earth pressures and horizontal displacement were done for the saturated soft clay deep foundation pit with the depth of 11.0m. The pit was braced by bored piles at vertical, and supported by two reinforced concrete brace at level. The active earth pressure measured is greater than the value calculated according to the formula of Rankine active earth pressure, and the measured value is about 1.20 times of the calculated value. The ratio of active earth pressure measured to active earth pressure calculated on the bulge site is greater than that at the normal position, and about 1, 13 times of the normal position. The measured active earth pressure and the measured horizontal displacement behind the braced wall in soil body are accordance with the hyperbola law. When the soil reaches the state of active earth pressure, the corresponding horizontal displacement of the soil behind the wall is about 0. 1% of the excavation depth.