南水北调渠基三通管受力特性与强度评定研究

Mechanical Characteristics and Strength Evaluation of Tee Pipe in Canal Foundation of South-to-North Water Diversion Project

南水北调挖方渠段渠底设置的塑料三通管是连接逆止阀与渠基透水暗管的关键部件。在南水北调渠道修复工程中,为了形成干地修复条件,提出在该位置实施气囊封堵来有效阻断渠基暗管连通,形成相对封闭区,以便于渠道衬砌板维修。文章以南水北调中线某干渠三通管为原型,开展了等比尺室内封堵试验,并结合有限元软件ABAQUS进行数值模拟,研究了塑料三通管在封堵气囊的局部压力作用下的应力分布与变化规律,并进行强度评定。通过分析可知,在封堵气囊内压作用下,塑料三通管的应力集中主要发生在其肩部及腹部内壁区域;当工程中渠内水位为6 m时,即气囊内压上限为0.06 MPa,该三通管不会发生屈服与局部失效,因此,认为三通管是安全稳定的。该研究成果可为南水北调渠道修复工程中采用气囊进行封堵时三通管的安全评估提供依据。

The plastic tee pipe set at the bottom of the excavated canal section of the South-to-North Water Diversion Project is the key component of the connection between the check valve and the permeable concealed pipe at the canal foundation.In the restoration project of South-to-North Water Diversion Project’s canal,in order to form dry land restoration conditions,this paper proposes implementing gasbag plugging at this position to effectively block the connection of concealed pipes in the canal to form a relatively closed area so as to facilitate the maintenance of channel lining boards.The tee pipe of the main canal in the middle route of South-to-North Water Diversion Project is used as the prototype to carry out the equal scale indoor plugging test.Combined with the finite element software ABAQUS for numerical simulation,the stress distribution and evolution law of the plastic of plastic tee pipe under the local internal pressure formed by plugging gasbag are studied,and the strength evaluation is carried out.According to the analysis,the stress concentration of the tee pipe under the internal pressure of gasbag mainly appears on the shoulder and abdomen of the inner of the tee pipe.When the water level in the canal is 6m,that is,the upper limit of the pressure generated by the gasbag is 0.06 MPa,the tee pipe will not yield and produce local failure.So,it is considered that the tee pipe is safe and stable.The research results can provide a basis for the safety evaluation of tee pipe when gasbag is used for plugging in the channel repair project of South-to-North Water Transfer Project.