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大多数基坑底面低于地下水位面,在开挖前需要进行降水工程为施工提供干燥、安全的环境。由于降水历程中孔隙水压力消散和有效应力的增加,周围土体会产生固结压密,同时在基坑周围形成地下水的降落漏斗,最终导致地层的不均匀沉降,对坑周道路、建筑物及地下管线造成危害。在忽略土体的侧向变形及群井效应的前提下,引入非饱和土的有效应力原理,根据裘布依假定求出基坑降水后地下水位的降落曲线方程。采用分层总和法分别计算水位降落曲线上下非饱和土与饱和土的地面沉降量,叠加后得到最终坑周地面沉降量。结合数值模拟计算及工程实例监测数据对比分析,表明该方法具有较高的工程实用价值。
Most of the foundation pit bottom below the groundwater level, in the excavation before the need for precipitation engineering for the construction to provide a dry and safe environment. Due to the dissipation of pore water pressure and the increase of effective stress in the course of precipitation, the surrounding soil will produce consolidation compaction, meanwhile, the groundwater descending funnel will be formed around the foundation pit, which eventually leads to uneven settlement of the formation. Underground pipeline damage. Under the premise of neglecting lateral deformation and well grouping effect of soil, the effective stress principle of unsaturated soil is introduced, and the equation of the landing curve of underground water level after foundation pit dewatering is obtained according to the assumption of drainage. The stratified sum method was used to calculate the ground subsidence of unsaturated soil and saturated soil above and below the water level drop curve respectively. Combined with numerical simulation and engineering example monitoring data comparative analysis shows that the method has a high engineering value.