冲击载荷作用下路面结构的沉降及破坏特征

随着公路在导弹的无依托随机发射中扮演更加重要的角色，研究发射期间其在发射筒冲击载荷作用下的沉降及破坏特征对提高我国武器威慑力具有重要意义。选择低等级道路结构为研究对象，基于河南省、山东省、云南省及广东省的低等级道路统计信息，建立典型低等级道路结构的1/4简化计算模型，采用一种基于有限元和离散元耦合的显式数值分析方法CDEM，并引入塑性-局部化-破裂耦合的本构模型，实现冲击载荷作用下路面沉降的三维全时程模拟，显式地展现裂纹萌生和扩展过程，实现路面结构从连续状态到非连续状态的过渡。通过与落锤弯沉仪试验的监测结果对比验证道路简化模型的正确性及CDEM的计算精度，随后各选取一个沥青混凝土和水泥混凝土道路结构进行数值模拟，并从沉降量、破裂度、破坏特征等方面分析。计算结果表明:沉降量时程曲线与冲击载荷时程曲线变化趋势一致，沉降量在冲击载荷峰值点处达到最大值；破裂面主要产生于冲击载荷急剧增大时期，约占最终全部破裂面积的97%；破裂面大体分为路面结构层内的竖向破裂面和层间的水平破裂面，破坏类型包括拉伸破坏与剪切破坏；路面结构上部易产生环状破裂面，下部易产生径向破裂面。

The settlement and damage characteristics of pavement structure under impulse load

As the road plays a more important role in the missile’s unsupported random launch, it is of great significance to study the settlement and damage characteristics under the impulse load of the launching cylinder to improve the weapon deterrent force of China. The object of study is low grade road structure. Firstly, based on the statistical information of low-grade road structures in Henan, Shandong, Yunnan and Guangdong provinces, a 1/4 simplified calculation model for typical low-grade road structures is established. An explicit numerical analysis method CDEM based on FEM and DEM is introduced, and a plastic-localized-rupture coupled constitutive model is introduced to realize three-dimension full-time simulation of pavement settlement under impulse load, explicitly reveal the process of crack initiation and expansion, and realize the transition of the pavement structure from continuous state to discontinuous state. The correctness of the road numerical model and the calculation accuracy of CDEM are verified by comparing with the results of Falling Weight Deflectometer. Then the typical asphalt concrete and cement concrete road structures are selected for numerical simulation and analyzed from the aspects of the settlement, fracture degree and damage characteristics. The results show that the settlement time-history curve is consistent with the trend of the impulse load, and the settlement reaches the maximum at the peak point of the impulse load; the fracture surface is mainly generated during the period of sharp increase of the impulse load, accounting for 97% of the final total fracture area; the fracture surface is roughly divided into the vertical surface in the layer and the horizontal fracture surface between the layers, the failure type includes tensile failure and shear failure; the upper part of the pavement structure produces an annular fracture surface, and the lower part produces a radial fracture surface.