公路路基特长箱涵顶进模拟试验

为使公路路基特长箱涵顶进施工顺利实施,基于模拟试验模拟涵洞顶进的实际摩擦性状,将箱涵及周围土分别简化为混凝土模型与土模型,分析采取减阻措施前后混凝土与混凝土、混凝土与不同含水量的土之间的摩擦系数的变化规律,利用摩擦系数计算实际箱涵需求的顶进力。发现混凝土与混凝土之间的滑动摩擦系数平均为0.31,石蜡机油混合物作为混凝土与混凝土滑动减阻材料效果明显,摩擦系数平均为0.12,减阻61%,涵周土体含水量的变化对混凝土与土之间的摩擦系数影响较大,含水量越大摩擦系数越小。模拟试验结果表明:实际箱涵顶进时,须对涵洞轴线周围地质情况进行勘探,以掌握涵周土体的工程特性,进而提出合理的减阻技术。

Simulation experiment about oversize box culvert jacked into highway subgrade

In order to make oversize box culvert being jacked into highway subgrade smoothly,the actual friction status of box culvert was simulated,box culvert and surrounding soil were simplified for concrete model and soil model respectively,the mutative rules of friction coefficients between concrete and concrete,concrete and soils with different amounts of water were analyzed after and before diminishing fiction resistance,and the pushing force of box culvert was computed according to friction coefficients.It is found that the average coefficient of gliding friction between concretes is 0.31;the mixture of paraffin and engine oil can reduce the friction between concretes obviously,the average friction coefficient is 0.12,and 61% of the previous friction coefficient is reduced;the amount of water in soil body surrounding box culvert greatly influences the friction coefficient between concrete and soil,the bigger the amount of water is,the smaller the friction coefficient is.Simulation result shows that when box culvert is jacked,it is necessary to explore the geological condition surrounding box culvert in order to hold the engineering characteristic of surrounding soil body in hand and give reasonable technology to diminish fiction resistance.3 tabs,4 figs,15 refs.