服役条件下高铁路基桩网结构土工格栅张拉试验研究  

Experimental study on tensile testing of geogrids in pile-supported reinforced embankment of high-speed railway under service conditions

作　　者：于红园 刘舜 赵闯 边学成[1] 陈云敏[1] YU Hongyuan;LIU Shun;ZHAO Chuang;BIAN Xuecheng;CHEN Yunmin(College of Civil Engineering and Architecture,Zhejiang University,Hangzhou 310058,China)

机构地区：[1]浙江大学建筑工程学院,浙江杭州310058

出　　处：《铁道科学与工程学报》2024年第8期3015-3025,共11页Journal of Railway Science and Engineering

基　　金：国家自然科学基金杰出青年基金资助项目(52125803)。

摘　　要：桩网结构路基已经在软土地区的高速铁路建设中取得了广泛的应用,服役期地基过大沉降、地下水淹没桩顶等引起桩网结构不合理受力,甚至导致格栅张拉破坏,目前仍缺乏深入的针对性观测和分析。建立一个全比尺的桩网结构路基模型试验,开展正常路基、桩间土过大沉降、路基浸水和路基水位下降4组典型工况的试验。同时采用前期研发的高速铁路路基动力效应试验装置施加车速达360 km/h、轴重为17 t和25 t的列车移动荷载,利用沉降板加位移传感器测量桩土的沉降变形量,利用光纤传感器测定了每组工况下的格栅拉力变化和空间分布规律,研究不同工况下相同的列车长期荷载对土工格栅拉力的影响。试验结果表明:在列车荷载作用下正常路基的桩网结构格栅最大拉力为5.9 kN/m,位于桩帽边缘处,为格栅抗拉强度的11.8%;桩间土发生过大沉降后格栅拉力最大值仍位于同一位置即桩帽边缘处,为11.85 kN/m,为格栅抗拉强度的23.7%。水位上升后桩网结构格栅拉力下降,但在列车荷载作用下格栅拉力又迅速增长,最大拉力为12 kN/m,水位下降后在列车荷载作用下格栅最大拉力为10.5 kN/m。桩网结构路基的规范设计中对格栅拉力的计算偏于保守,模型试验结果对实际工程中桩网结构路基的设计以及理论方法的验证有一定的指导和借鉴意义。Pile-supported reinforced embankment has been widely applied in the construction of high-speed railways in soft soil areas.However,issues such as excessive settlement of the subgrade during the service period and submergence of the pile top by groundwater can often lead to unreasonable stress on the pile-supported reinforced embankment and even cause tension damage to the geogrids.Therefore,in-depth targeted observation and analysis are still needed.A full-scale experimental model of a pile-supported reinforced embankment was established,and experiments were conducted under four typical conditions:normal subgrade,excessive settlement of soil between piles,water-soaked subgrade,and water level decrease.The test device developed previously for simulating high-speed railway subgrade dynamic effects was used to apply moving loads from trains with speeds of up to 360 km/h and axle loads of 17 t and 25 t.Settlement plates and displacement sensors were used to measure the settlement deformation of the pile and soil,and fiber optic sensors were used to determine the changes and spatial distribution of geogrid tension under each working condition.The impact of the same long-term train loads on geogrid tension under different conditions was investigated.The test results show that under the train load,the maximum tension of the geogrid in the normal subgrade is 5.9 kN/m,located at the edge of the pile cap,which is 11.8%of the tensile strength of the geogrid.After excessive settlement occurs between the piles,the maximum tension of the geogrid remains at the same location,the edge of the pile cap,reaching 11.85 kN/m,which is 23.7%of the tensile strength of the geogrid.After the water level rises,the tension of the geogrid decreases,but under the train load,the geogrid tension rapidly increases again,with a maximum tension of 12 kN/m.After the water level drops,the maximum tension of the geogrid under the train load is 10.5 kN/m.The calculation of geogrid tension in the standard design of pile-net structure subgrades tends to

关 键 词：高速铁路 桩网结构 路基 模型试验 土工格栅 

分 类 号：TU472[建筑科学—结构工程]