冻融循环对严寒地区路堤最大填土高度的影响

Effect of Freeze-thaw Cycles on Maximum Fill Height of Sub-grade Soil in Severe Cold Areas

针对严寒地区的特殊环境,采用静三轴试验,测试了长春地区3种典型路基土在不同冻融循环次数作用下的粘聚力和内摩擦角变化规律.在考虑汽车荷载、冻融作用和实际地理因素的基础上,采用层状体系有限元模型,计算了1∶1. 5坡度工况下,3种路基土在经历不同冻融次数后路堤最大填土高度.研究表明,随冻融次数增加,路堤最大填高逐渐降低且逐步趋于稳定,最大降幅近39. 3%.在最佳含水量时,粉质粘土路堤的最大填高可达20. 3m,粉砂土路堤的最大填高仅为8. 5 m,然而,考虑到实际设计与应用情况,应取安全系数为2所对应最大填高进行设计取值.在选取路堤填土材料时,如遇粉砂土的高填方路堤,对其进行改良后方可使用.

The cohesion and internal friction angle of three typical sub-grade soils in Changchun were tested under different water content and freeze-thaw cycles based on the static tri-axial test for the special environment of severe cold area. With the finite element model of layered system,the maximum fill height before the slope instability was studied after different freeze-thaw cycles under the slope of 1:1. 5 based on considering the vehicle load,freeze-thaw cycles and the actual geographical environment factors. The results indicate that with the increase of the number of freeze-thaw cycles,the maximum fill height of sub-grade gradually decreased and stabilized,which the maximum decrease can reach 39. 3%. With the condition of the optimal water content,the maximum fill height of silty clay sub-grade could reach 20. 3 m,while the maximum fill height of silty soil sub-grade was only 8. 5 m.However,congidered the actual design and application of the situation,safety factor should be taken 2 as the corresponding maximum fill height for design values. Therefore when selected fill materials,in case of silty soil land section of high fill sub-grade,silty soil should be improved before use.