基坑降水引起的地基附加应力及沉降简化计算

Simplified Calculation of Ground Settlement and Additional Stress Caused by Foundation Pit Dewatering

探讨了基坑降水导致周围地基沉降的机理,通过借鉴水库水位下降时的水面曲线计算公式,并简化和分解由降水导致的附加荷载后,推导出一套计算基坑降水引起的地基附加应力和地表沉降的理论计算方法。本方法可以综合考虑水位降深和水面曲线形状等因素的影响,计算结果能比较准确的反映水面曲线以下附加应力的衰减效应,相比传统计算方法更具合理性。笔者利用本理论计算方法对某基坑工程降水实例进行了计算,通过对比分析本方法计算结果及数值模拟和实测值后发现,本方法计算得到的地基附加应力和地表沉降分布规律与数值模拟和实测值基本吻合,误差范围均在15%以内,验证了本计算模型的有效性。

The mechanism of additional stress and settlement caused by dewatering in pit engineering was studied. Based on the phreatie surface calculation theory of reservoir, a simplified method for computing additional stress and ground settlement near pit was proposed through simplifying and decomposing the additional load caused by dewatering. In this method, groundwater drawdown and the shape of phreatic surface were considered. The attenuation effect of the additional stress under the phreatic surface was reflected in the calculated results. In comparison with traditional calculation method, this novel method is more effective and rational. Instance calculates was performed in an engineering example of foundation pit dewatering by finite element software Abaqus, and comparative analysis was carried out between numerical results and measured field data. Analysis results suggested that the additional stress and settlement distribution calculated by this method were basically within error limit of 15%, which validated the effectiveness of the calculation model.