基于落锤式弯沉仪的路基表面弯沉试验技术要点分析

Analysis on Key Points of Subgrade Surface Deflection Test Technology based on Falling Weight Deflectometer

依托广东省内某高速公路路基工程,开展落锤式弯沉仪路基表面弯沉试验技术要点研究。选定长度为300 m的填方试验区域1和长度为400 m的填挖结合试验区域2开展试验研究。根据编制的试验方案,于两个试验区域分别布置了多条FWD测线,基于获得的路基表面弯沉数据,开展了FWD设备量程要求、FWD第1锤数据取舍、FWD同一测点加载次数、FWD荷载级位、测点间隔距离、土质类型和路基类型等影响因素的分析。研究结果显示,FWD用于路基表面弯沉试验时,其对路基土质类型和路基类型有较强的敏感性;但FWD用于路基弯沉试验时,其量程需满足一定要求,同时,同一测试点第1锤数据需舍弃,以5次锤击数据的后4锤数据的平均值作为该测试点的弯沉值;测试点间隔距离对于路段的代表值影响较小,但单点弯沉数据对于评价路段压实均匀性是有利的;不同FWD荷载级位下的路基表面弯沉值存在差异,其弯沉大小并非与荷载呈现简单的正比关系。因此,FWD用于路基表面弯沉试验与用于路面弯沉试验有一定差异,需满足一定技术要求。

Based on a highway subgrade project in Guangdong Province,the key technical points for subgrade surface deflection test are studied by using the falling weight deflectometer.The filling test area No.1 with a length of 300 m and the combined test area No.2 with a length of 400 m are selected to carry out the experimental research.According to the prepared test plan,several FWD lines are arranged in the two test areas.Based on the obtained subgrade surface deflection data,an analysis is conducted on factors affecting the FWD equipment range requirements,FWD first hammer data selection,FWD loading times at the same measurement point,FWD load level,measurement point spacing distance,soil type,and roadbed type.The research results show that the results show that FWD is sensitive to the type of subgrade soil and the type of subgrade when it is used in the subgrade surface deflection test.However,when FWD is used in subgrade deflection test,its range must meet certain requirements,and the first hammer data at the same test point must be discarded,the deflection value of the test point is taken as the average value of the last 4 hammers of the 5 hammering data.The distance between test points has a small impact on the representative value of the road section,but single point deflection data is beneficial for evaluating the compaction uniformity of the road section.The surface deflection of subgrade under different FWD load levels is different,and the deflection is not directly proportional to the load.Therefore,there is a certain difference between FWD used for roadbed surface deflection test and pavement deflection test,and it must meet certain technical requirements.