富水深基坑降水引起的地表沉降预测

随着城市轨道交通的发展,富水地区地铁深基坑降水引发的工程问题时有发生,引起广泛关注。传统算法计算地基沉降只考虑降水前后土体自重应力的变化。在此基础上进一步考虑渗流动水压力引起的有效应力变化和止水帷幕对土体沉降的约束影响,提出一种简化的计算降水引起基坑外地表沉降的方法。并结合实际工程对该方法进行验证。结果表明:考虑地下水渗透力的影响使降水后土体有效应力较不考虑渗流时增加5%左右,地下水渗流对土体有效应力的影响不可忽略。止水帷幕对土体沉降的约束影响在距支护结构1倍降水深度范围内,计算该范围内土体沉降需将止水帷幕影响考虑在内。同时考虑降水前后自重应力变化、渗透力影响、止水帷幕约束这三者的共同作用,得出的理论计算结果与实测值误差在12%以内,验证了计算方法的有效性。

Prediction of Surface Subsidence Induced by Deep Foundation Pit Dewatering

With the development of urban rail transit, the engineering problems caused by the dewatering of deep foundation pit in the subway in the water-rich area have occurred frequently, and the problems have aroused wide attention. The traditional algorithm only considers the change of gravity stress before and after dewatering, on this basis, this paper further considers the effective stress change caused by seepage flow water pressure and the restraint effect of waterproof curtain on soil settlement, and puts forward a simplified method to calculate the ground settlement caused by dewatering. Then, the method is verified by practical engineering. The results show that considering the influence of groundwater permeability, the effective stress of soil after precipitation increases by about 5% compared with that without considering seepage, and the effect of groundwater seepage on the effective stress of soil cannot be ignored. The restraint effect of water-stopping curtain on soil settlement is within the influence depth range of 0.5 times of precipitation from the supporting structure, and the influence of water-stopping curtain should be taken into account when calculating the soil settlement in this range. At the same time, considering the joint action of gravity stress before and after precipitation, the influence of infiltration force, and the restraint of water curtain, the error between the theoretical calculation result and the measured value is within 12%, which verifies the effectiveness of the calculation method.