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通过有限元Plaxis软件,对厦深高速铁路潮汕车站的超大面积深厚软土桩-网复合地基承载性状进行全断面数值模拟,系统地分析了其沉降变形、土压力变化、桩体受力、土工格栅拉力、超孔隙水压力变化等情况。结果表明:土层的沉降随填筑高度的变化具有一定的间歇性,沉降主要集中于加固区下面的下卧层中;土压力的发展变化呈现出明显的阶梯状,并贯穿于整个施工阶段。在竖向,管桩桩体轴力的峰值出现在淤泥质黏土层顶部,而没有出现在桩体顶部;在横向,沿路基中心向外,桩体剪力及弯矩依次逐渐增大。土工格栅的最大拉力出现在桩帽边缘处,桩间的拉力较小,在管桩顶部加设桩帽有助于均匀格栅中的拉力,避免局部应力集中;桩端土层以下超孔隙水压力随填筑加载而增长的幅度较大,桩端土层以上则较小,桩体有效地将上部荷载传递到深部较好土层,减轻了浅部软弱土层的负担,从而达到控制沉降的目的。
Through the finite element Plaxis software, the full-section numerical simulation of the bearing capacity of ultra-large area deep soft soil-soil-pile composite foundation at Chaoshan station of Xiamen-Shenzhen high-speed railway was carried out. The settlement deformation, the change of earth pressure, Grid tension, excess pore water pressure changes and so on. The results show that the settlement of the soil layer changes intermittently with the filling height, and the settlement mainly concentrates in the sub-layer below the reinforcement zone. The development and change of the earth pressure shows obvious step-shape and runs through the whole construction period . In the vertical direction, the peak value of the axial force of the pile body appears at the top of the silt clay layer but not at the top of the pile body. In the transverse direction, the shear force and bending moment of the pile body gradually increase along the outward direction of the subgrade. The maximum tensile force of geogrid appears at the edge of pile cap, and the tension between piles is small. Adding a pile cap at the top of the pile helps the tension in the uniform grid to avoid local stress concentration. Water pressure increases with the loading and filling of the larger, more than the top of the pile is smaller, the pile effectively to the upper part of the load is transmitted to the deeper soil, reducing the burden on shallow soft soil in order to achieve control The purpose of settlement.