由于受到经济或技术因素影响,当基坑所在承压水层埋深范围较大时,承压水层未被地连墙完全隔离,基坑内外水流在地连墙底部流动。为研究在基坑内外承压水层未完全隔离条件下基坑内不完整井降水引起坑外地表沉降变化,以深圳某地铁车站基坑工程为例,采用模型试验及理论分析研究手段,揭示了典型承压水层绕渗引起水位变化规律,提出了承压水层不完整井降水有效影响深度确定方法、坑外水位变化曲线公式及绕渗区范围确定方法。基于上述理论研究,提出考虑绕渗影响坑外地表沉降计算方法,通过与试验对比,可较准确反映绕渗作用下坑外地表沉降变化。上述成果为类似区域基坑降水引起坑外地表沉降的研究提供了理论基础。
Due to the influence of economic or technical factors, when the buried depth of the confined water layer is large at the location of the foundation pit, and the water flow inside and outside the foundation pit flows at the bottom of the diaphragm wall. To study the change of surface settlement outside the foundation pit caused by incomplete well dewatering in the foundation pit under the condition that the foundation pit is not completely isolated, taking a foundation pit of subway station in Shenzhen as an example, the model test and theoretical analysis are used to reveal the change law of water level caused by the seepage of typical confined water layer. The method for determining the effective influence depth of dewatering of incomplete wells in confined water layer, the formula of water level change curve outside the pit and the method for determining the range of seepage area are put forward. And based on the above theoretical research, the calculation method of surface settlement outside the pit considering the influence of seepage is proposed. Compared with the test, it can accurately reflect the change of surface settlement outside the pit considering the influence of surrounding infiltration. The above results can be provided as theoretical foundation for the study of surrounding surface deformation out of foundation pit caused by dewatering in foundation pit.
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