新疆砾石土低路堤动力特性

Dynamic characteristics of gravel soil low embankment in Xinjiang

以新疆三岔口-莎车高速公路为依托,基于标准轴载作用下单轮影响范围内的1∶1路基模型试验,分析了车辆荷载下低路堤的动力特性;考虑了绿洲区地基在服役期间不同的含水率状态,根据一般道路设计标准,将低路堤道路结构分为面层、基层、路基与地基四部分,模拟了低路堤在不同荷载作用下的动力特性,研究了动载峰值、频率与重复作用次数对低路堤动力特性的影响。研究结果表明:不同加载方式下的竖向应力均随路基深度增大而迅速减小,应力在距路基顶面0.8 m深度处均衰减了69.2%;静载和短时动载作用下各深度处的应力随荷载呈线性变化趋势,应变则呈非线性变化趋势;由于不同土层模量的差异,使得应变在路基与地基中出现了明显的分层现象;地基含水率的变化对低路堤动力特性的影响非常明显,当地基含水率从18%增大到28%时,地基顶面处的应变增大了1.8倍;短时动载频率的增大对应力和应变的影响都很小,当动载频率由1 Hz增大到5 Hz时,路基与地基顶面处的应力分别减小了7%和9%;当静载、短时动载和长时动载的峰值为50 kN时,短时动载峰值作用下路基与地基顶面处的应力和应变分别是静载作用的79%~95%和75%~95%,而长时动载引起的路基与地基顶面处的应力和应变分别是静载作用的1.0~1.1倍和1.9~3.3倍。

Based on the Sanchakou-Shache Expressway in Xinjiang,the subgrade model test with 1∶1 ratio was carried out within the influence range of one wheel for the standard axle load,and the dynamic characteristics of low embankment were studied under vehicle load.The different moisture content states of the subsoil in service in the oasis area were considered,the low embankment road structure was divided into four parts,including pavement,base,subgrade,and subsoil according to the general road design standards,the dynamic characteristics of low embankment under different loads were simulated,and the effects of peak values,frequencies and repetition times of dynamic loads on the dynamic characteristics were studied.Research result indicates that the vertical stresses under different loading cases decrease rapidly with the increase of subgrade depth,and attenuate by 69.2%at the depth of 0.8 m.The stresses at different depths vary linearly with the static and short-term dynamic load,while the strains show a nonlinear trend.Due to the modulus difference of different soil layers,the strains appear obvious stratification in the subgrade and subsoil.The change of water content of the subsoil has obvious influence on the dynamic characteristics of low embankment,and the strain at the top of the subsoil increases by 1.8 times when the water content increases from 18%to 28%.The increase of short-term dynamic load frequency has little effect on the stress and strain,and they decrease by 7%and 9%,respectively when the frequency increases from 1 Hz to 5 Hz at the tops of the subgrade and subsoil.When the peak values of static load,short-term dynamic load and long-term dynamic load are 50 kN at the tops of the subgrade and subsoil,the stress and strain under the short-term dynamic load are 79%-95%and 75%-95%of the values under the static load,respectively,while the stress and strain caused by the long-term dynamic load are 1.02-1.11 and 1.9-3.3 times of the values under the static load,respectively.2 tabs,12 figs,29 refs.