排水砂槽渗流试验与Signorini型变分不等式方法验证

排水是岩土体及工程构筑物渗流控制的主要措施之一，其实质是通过在渗流域内形成潜在溢出边界或低水位边界而实现渗流控制的。在排水渗控条件下，渗流场往往具有强烈的边界非线性特征，Signorini型变分不等式方法从理论上为稳定和非稳定排水渗流问题提供了有效的分析方法，但其实际效果还需要得到试验的验证。通过开展含5个排水廊道的排水砂槽模型试验，研究了复杂排水条件下砂土渗流的基本规律，并通过试验数据与数值计算成果的对比分析，论证了Signorini型变分不等式方法的有效性和正确性。试验结果表明，在稳定渗流条件下，排水砂槽上游侧3个排水廊道对渗流控制起主导作用，而下游侧2个廊道则失去排水功能，数值计算与试验成果吻合较好；在非稳定渗流条件下，受测压管精度、砂样均匀性和毛细效应的影响，数值计算与试验成果存在一定偏差，但也较好地揭示了复杂排水条件下砂槽中的非稳定渗流特征。排水砂槽试验结果验证了Signorini型变分不等式方法的有效性和正确性，为复杂排水条件下岩土体及工程构筑物的渗控结构优化设计提供了有效的分析手段。

Seepage flow test on drain sand flume and validation of variational inequality method of Signorini condition

Draining is one of most effective seepage control measures for geomaterials and engineering structures,of which the essence is through forming the potential spillover boundary or low water level boundary in flow region to realize the seepage control.Induced by the seepage boundary of drains,the seepage flow may exhibit a strong nonlinear effect.The variational inequality formulation of Signorini condition has been theoretically proved to be an effective approach for steady and non-steady seepage problems with drains,but needs further experimental validations.For this purpose,a laboratory test is performed on the seepage behavior in a sand flume with five horizontal drainage galleries,then the effectiveness and correctness of the variational inequality method of Signorini condition is validated by experimental data.The experimental results show that: in steady seepage flow condition,the upstream three drainage galleries in the sand flume have a dominant effect on controlling the seepage flow,while the other two drainage galleries in the downstream side lose the draining effect;and the numerical results agree well with experimental observations.In non-steady seepage flow condition,the numerical results somewhat deviate from the experimental results due to low accuracy of piezometer tubes,inhomogeneity of the sand sample and negligence of capillary effect.The non-steady seepage flow process in the sand flume with complex drains,however,is still satisfactorily demonstrated.The effectiveness and correctness of the variational inequality method of Signorini condition is validated by the seepage flow test;and it provides an effective approach for optimization design of seepage control structure in geotechnical engineering under complex drains.