Experimental study on tensile testing of geogrids in pile-supported reinforced embankment of high-speed railway under service conditions
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 be conservative. The results have certain guiding and reference significance for the design of pile-supported reinforced embankment in actual projects and the verification of theoretical methods.
万方数据
维普
