河水位升降下饱和-非饱和驳岸岸坡稳定性分析

Analyses on Stability of Saturated-Unsaturated Bank Slope with Revetment During Rise and Fall of River Level

岸坡失稳常常与河水升降密切相关。为了分析水位升降对福州晋安河驳岸岸坡稳定性的影响,根据某段岸坡的工程地质条件,建立驳岸岸坡饱和-非饱和渗流计算模型,结合引水冲污工程,研究河水位不同升降型式对稳定性的影响。结果表明,坡脚淤泥的堆积阻碍了坡内孔隙水的变化,表现为在其影响范围内,河水上涨时水流难以流入,水位下降时则孔隙水不易排出;水位上升越快,驳岸越稳定,较大的水位下降速度则对其稳定性不利;水位频繁升降,由于岸坡排水条件不佳,孔隙水进一步赋存,稳定性降低;在引水冲污工程中应做好水位下降速度的控制和坡内孔隙水的疏排;在对岸坡进行加固时,可采取置换坡脚淤泥为良好透水材料的措施。

The bank slope failure is closely related to the rise and fall of river level generally.In order to analysis the influence of the rise and fall of river level on Jin'an River bank slope stability in Fuzhou,the saturated-unsaturated seepage of bank slope with revetment was modelled based on the engineering geological condition of some bank of Jin'an River,and the effect of rise and fall of river induced by the DRWWOS(Drawing River Water to Wash Out Sewage)project on bank slope stability was studied.The results show the silt lying on the slope toe impedes pore water change,manifesting as in its sphere of influence river water is hard to flow into the bank when river rises,and the pore water pressure can not dissipate in time when drawdown. The faster the river rises,the more stable the bank slope becomes.On the contrary,the larger river level falling rate is more likely to leads to bank slope failure.Due to the poor bank drainage performance,the frequent rise and fall of river level results in pore water pressure increasing further,then impairing the bank slope stability.During DRWWOS project,the river level falling rate control and pore water pressure dissipation must be paid enough attention to.Also,replacing silt lying on the slope toe by good permeable material is a good choice to reinforce the bank slope.