浅覆土特长箱涵顶进结构受力特性数值分析

Numerical Analysis on Mechanical Characteristics of Jacking Device for Shallow Soil-covered and Over-long Box Culvert

为了探明顶进施工中浅覆土特长箱涵顶进结构的受力特性,结合广东地区某工程实例,通过三维有限元模拟分析了不同顶进长度、覆土厚度及摩阻系数等工况条件下浅覆土特长箱涵顶进结构的应力应变变化规律及顶进施工扰动影响范围,结果表明:相同工况条件下,随着顶进长度增加浅覆土特长箱涵顶板和底板的应力与应变呈现靠椅状变化趋势,而其腹板的应力与应变则呈现倒梯形截面变化趋势;涵顶覆土厚度及其性状对浅覆土特长箱涵顶进结构的应力与应变影响较大,涵顶覆土厚度越厚土体越密实,箱涵结构所受应力与应变越大;受顶进施工影响,涵顶上覆路面的沉降量为7.0~17.1 mm,沿顶进方向路基路面受扰动影响范围为23~30 m,与采用泥浆减阻措施相比采用石蜡+机油措施的减阻效果更为有效。

In order to find out the mechanical behavior of shallow soil-covered and over-long box culvert in the jacking construction process, combining with a project example in Guangdong area and based on 3D finite element simulation, the change law of stress and strain of the jacking device and the jacking disturbance influence area are studied under the conditions of different lengths, covering thicknesses and friction coefficients are studied. The result shows that （ 1 ） under the same working condition, with the increase of the jacking length, the stress and strain of the top and the bottom plates of the box culvert show the ＂arm-chair＂ change shape, while the stress and strain of the web show the trend of ＂trapezoidal cross-section＂ ; （2） the thickness and the character of the cover soil at the top plate of the box culvert have great influence on the stress and strain of the box culvert structure, the thicker and the more dense the covered soil, the greater the stress and strain of the box culvert structure; （3） by the affect from box culvert jacking construction, the pavement settlement at the top of the box culvert is in the range of 7.0 - 17. 1 mm, and the scope of the disturbed roadbed and road surface along the jacking direction is 23 -30 m; （4） the drag reduction effect of paraffin oil mixture is more effective than that of the slurry drag reduction.