循环动载作用下无砟轨道混凝土裂缝内动水压力研究

Research on Internal Dynamic Water Pressure in Concrete Crack of Ballastless Track under Cyclic Dynamic Load

摘要: 无砟轨道是我国高速铁路主要结构形式，根据现场病害调查，底座板与CA砂浆粘结层的裂缝较为普遍，多雨地区其伤损更为严重，出现翻浆冒泥现象。在循环动载作用下，假定裂缝形状为楔形，裂缝边缘张开闭合速度呈正弦规律变化，推导出裂缝在动力荷载作用下因水压缩产生的缝内水压计算式。通过试验验证，分析了裂缝边缘张开闭合速度(加载速度)、裂缝初始张开宽度(荷载大小)对缝内最大附加水压的影响规律。研究表明，加载频率是影响裂纹内部水压力的重要因素。当加载幅值不变时，随着加载频率的增加，裂纹内水压力增大。当加载频率不变时，荷载幅值对裂纹内部水压力有重要的影响。当加载频率不变时，裂纹内部某一点的压力，随着荷载幅值的增加而增大，二者可拟合为一个多项式关系。

Abstract: The ballastless track is the main structure of the high-speed railway in China. According to the disease survey, cracks of base plate and the CA mortar bonding layer are widespread, and its damage in pluvial region is more serious, with the mud pumping in phenomenon. Under cyclic dynamic load, with the assumption that the crack is wedge-shape and that the velocity of crack edge accords with sine rule, a calculation formula is derived to calculate the internal water pres-sure in cracks under dynamic load due to compression of seam water. The effect of crack edge’s velocity (loading velocity), and crack edge’s initial width (load size) on the additional water pressure and stress intensity factor is analyzed by test. The study shows that load frequency is an important factor to influence water pressure inside the crack. When loading at constant amplitude, with the increase of loading frequency, the internal pressure will increase. When loading at constant frequency, load amplitude has important effect on crack internal water pressure. When loading at constant frequency, crack within a point of stress will increase with the increase of load amplitude, and the two can be fitting for a polynomial.