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公路拓宽改建是适应交通运输能力增长的重要应对措施,而由于新旧路基材料性质不同导致的差异沉降和路基稳定性是该类工程建设过程中需重点关注的关键问题。针对公路拓宽改建的工程问题,采用连续-离散耦合数值分析方法,对路堤边坡断面建立二维模型,连续、离散网格区域分别采用有限差分连续元和颗粒离散元进行建模。基于模型不平衡力变化规律、细观接触力链与宏观变形特征、细观配位数与土体沉降机理等模拟结果,从宏观和细观两个角度协同分析拓宽路堤差异沉降及其对路基变形的影响,并针对采用轻质土方式进行道路拓宽的工程效果进行了模拟分析。结果表明:(1)细观颗粒的不平衡单元面积比参数可与宏观不平衡力共同判定计算模型的收敛性及计算结果的合理性;(2)路基拓宽前后,细观接触力的分布规律可表明土体宏观位移变化的发展方向;(3)模型中细观颗粒在计算过程中的配位数变化可解释土体沉降变形机理;(4)采用轻质土换填方式拓宽路基,可大幅减少路基的沉降变形及新旧路堤的差异沉降,表明该技术应用于软土区域的公路拓宽工程具有显著优势;(5)连续-离散耦合分析方法可反映公路路基变形破坏的力学机制及差异沉降产生的内在本质,可在岩土工程灾害防控措施及其机理研究方面进一步推广应用。
Widening and rebuilding of the highway is an important countermeasure to adapt to the growth of transportation capacity. However, due to the different nature of the old and new subgrade materials, the differential settlement and the stability of roadbed are the key issues that need to be paid more attention to during the construction of such projects. Aiming at engineering problems of widening and rebuilding of highway, a two-dimensional model of embankment slope section is established by using continuous-discrete coupled numerical analysis method. The continuous and discrete grid regions are modeled by finite difference continuous element and particle discrete element respectively. Based on the simulation results of variation of unbalance force, mesoscopic contact force chain and macroscopic deformation, mesomechanical coordination and soil settlement mechanism, the paper analyzes the widening of differential settlement and its influence on embankment from both macro and micro perspectives The effect of deformation on the road is analyzed and the engineering effect of widening road with lightweight soil is simulated. The results show that: (1) the imbalanced unit area ratio of mesoscopic particles can be judged with the macro unbalanced force and the convergence of calculation model and the rationality of calculation results; (2) The distribution of mesoscopic contact force before and after the embankment is broadened (3) The variation of coordination number of mesoscopic particles in the calculation process can explain the deformation mechanism of soil mass; (4) The embankment can be widened by light soil exchange, Which can significantly reduce the settlement and deformation of the subgrade and the differential settlement of the old and the new embankments. It shows that this technique has significant advantages in highway widening project in soft soil area. (5) The continuous-discrete coupled analysis method can reflect the mechanical mechanism and differential settlement of highway subgrade deformation and failure The inherent nature of the geotechnical disaster prevention and control measures and its mechanism can be further promoted and applied.