铁路隧道端墙式洞门墙背土压力研究

Study of earth pressure acted on end wall tunnel portal

隧道洞门处于结构和边坡结合处,洞门结构体系受力复杂。采用三维有限元数值分析方法对140km/h单线和双线铁路隧道端墙式洞门土压力进行计算,并将计算结果与乌氏公式计算结果进行对比。研究表明:洞门墙背土压力等值线呈"C"形,开口朝向隧道拱肩,最大值位于拱肩,并由拱肩向端墙最左端角点方向递减,直至为0;条带土压力合力的有限元计算结果约为乌氏公式计算结果的0.44倍;有限元计算结果认为条带合力作用点位于条带高度的中部,比乌氏公式计算结果提高约0.2倍的条带高度。提出了墙背条带土压力分布形式为曲线段和直线段组合的计算方法,该方法考虑了拱肩等高处最大土压力对端墙的最不利影响和计算过程的简便性,为铁路隧道洞门墙背土压力的分析和计算提供了一种有效的途径和方法。

This paper studies earth pressure acted on end wall tunnel portal by means of three dimensional finite element numerical simulation method,and the results are analyzed comparing with the calculation results of Wu' s formula. The results show that earth pressure contour acted on end wall tunnel portal follows a C type. The earth pressure contour increases gradually from the top left point of end wall tunnel portal to the arch shoulder,and the maximum active earth pressure occurs at the arch shoulder. Earth pressure acted on the strip of end wall tunnel portal increases with the height of the strip below the arch shoulder height,and then decreases gradually until extinction with the remaining height of the strip. The strip's resultant earth pressure of numerical calculation is 0. 44 times of the calculation results of Wu 's formula. The applied point of the resultant earth pressure of numerical calculation is located in the middle of the strip in the vertical direction. Based on Wu' s formula theories and three dimensional finite element calculation results,a new comparatively simple and convenient method is proposed to calculate active earth pressure of the strip of end wall tunnel portal. The results can provide a valid method for analysis of earth pressure acted end wall tunnel portal.