公路边坡数值模型几何尺寸的影响分析

Influence of Geometric Dimension on Highway Slope in Numerical Analysis

公路边坡设计中,需对各种设计方案进行数值仿真以验证其合理性。为了提高计算效率,数值模型构建过程中需在解算速率及解算结果准确性之间达到平衡。为准确评估数值模型对边界尺寸的敏感性,并取得较为合理的计算结果,常采用FLAC 3D软件与强度折减法分别对二维和三维模型进行分析,并通过调整边界尺寸取值、边坡角度和三维模型的宽度,对计算结果进行统计分析,以研究模型几何参数对安全系数的影响,从而确定仿真模型的最优边界尺寸。研究结果表明:1)二维模型边界尺寸对安全系数的影响与坡角有关,且当坡角为45°时,计算结果对模型几何尺寸的取值变化最敏感;当坡体顶端与坡脚分别距数模边界的距离为坡高H时,计算所得坡体的安全系数偏小;当坡体顶端与坡脚分别距数模边界的距离不小于1.5 H时,计算结果较为可靠;2)对于三维模型,若坡角小于45°,可取模型左右侧边界及宽度不小于H,下边界不小于1.5 H;若坡角大于45°,则模型宽度应不小于1.5 H。

In the process of highway slope design,numerical simulation is required to be done for various schemes to verify the rationality.To enhance the calculation efficiency,the calculation speed and accuracy should level off when building numerical model.To accurately evaluate the influence of boundary dimension on the numerical model and obtain a more reasonable result,the 2D and 3D numerical model were analyzed respectively using FLAC 3D software and strength reduction method.Based on the changed boundary size,the slope angle,the width of 3D model and by analyzing calculated results statistically,the influence of geometric parameters on the safety factor was analyzed to determine the best boundary size of the model.The study shows that the influence of boundary size of 2D model on safety factor is associated with slope angle,the calculation results are most sensitive to the geometric dimension when slope angle is 45°.The calculated safety factor of the slope is samll when both left boundary size and right boundary size are the slope height(H).The results are reliable when both left boundary size and right boundary size are not less than 1.5 H.For 3D model,the left boundary and right boundary of model and its width should be not less than H,basis boundary not less than 1.5 H,when slope angle is less than 45°,the width of the slope should be greater than or equal H,when slope angle greater than 45°,the width of the slope should be greater than or equal to 1.5 H.