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为合理控制高速公路改扩建施工时开挖临空面后的路基稳定性和行车安全,通过建立有限元仿真模型,全面分析了临空面开挖高度、车辆荷载作用位置以及路基土质对开挖临空面路基工作状态的影响,对粘性土、砂性土和碎石土3种不同土质的路基、不同工况条件下的开挖临空面路基稳定系数进行了计算,在此基础上提出了高速公路改扩建路基开挖临空面安全控制标准。结果表明:临空面开挖高度和荷载作用位置对路基稳定性影响较大,临空面高度应控制在2.0m内,路侧安全距离应为1.5～2.0m;路基土质对路基稳定性影响相对较小,粘性土路基稳定性最好,依次是砂性土和碎石土;根据路基稳定系数的差异性,将路基高度分为:小于1.0m,1.0～1.5m,1.5～2.0m,2.0～3.0m和3.0～3.5m这5个等级,以稳定系数1.80为控制指标,制定了路基开挖临空面安全控制标准。
In order to rationally control the roadbed stability and driving safety after the excavation of the free surface during the reconstruction of expressway, the paper analyzes the excavation height, the position of the vehicle load and the excavation of the subgrade soil through the establishment of the finite element simulation model The influence of the working condition of the subgrade on the ground surface, the stability coefficient of the subgrade under the excavation and excavation under different working conditions have been calculated on the basis of three kinds of soil with clay, sandy soil and gravel soil, on the basis of which Freeway expansion subgrade excavation face safety control standards. The results show that the excavation height and the location of load have a great influence on the stability of the subgrade. The height of the caving surface should be controlled within 2.0m and the safety distance on the roadside should be 1.5-2.0m. The influence of subgrade soil on the stability of subgrade The stability of the subgrade is relatively small, and the sandy soil and gravel soil are the best in turn. According to the difference of subgrade stability coefficient, subgrade height is divided into: less than 1.0m, 1.0 ~ 1.5m, 1.5 ~ 2.0m, 2.0 ~ 3.0m and 3.0 ~ 3.5m. With the stability coefficient of 1.80 as the control index, a safety control standard for the safety of subgrade excavation was formulated.