高速铁路地基膨胀泥岩变形试验及计算研究*

为研究某高铁地基膨胀泥岩在含水率和上覆荷载共同作用下的膨胀变形规律，通过室内试验和理论推导，分析地基膨胀泥岩的膨胀量随时间增长及含水率增加的变化规律。结果表明:无荷载地基膨胀泥岩的膨胀量随时间增加呈阶梯式持续增长趋势；有荷载地基膨胀泥岩的膨胀量在上覆荷载作用初期减小，然后随时间增加呈阶梯式增长趋势，膨胀变形结束时间约为45 h。含水率对该地基膨胀泥岩的膨胀变形影响较大，在无荷载试验中膨胀量随含水率的增加而增加；对于有荷载试验，膨胀量随含水率的增加多呈先减小后增大的趋势，地基膨胀泥岩对应含水率为23%~25%时膨胀变形稳定。从力学理论出发，利用弹性力学中的物理方程并引入膨胀率，推导地基膨胀泥岩在含水率和上覆荷载共同作用下及无上覆荷载时的膨胀量计算公式，发现含水率大于7%时，公式计算结果与试验结果最大相对误差为14.87%，可为实际工程提供理论支撑。

Test and calculation study on deformation of foundation expansive mudstone in high-speed railway

To study the expansion and deformation laws of foundation expansive mudstone under the combined effect of water content and overburden load in a high-speed railway,the changing laws of the expansion amount of foundation expansive mudstone with the increase of time and water content were analyzed through the laboratory tests and theoretical derivation.The results showed that the expansion amount of unloaded foundation expansive mudstone increased continuously in a multistep pattern over time,while the expansion amount of loaded foundation expansive mudstone decreased at the initial stage of overburden load action,then it increased in a multistep pattern over time,and the duration of expansion deformation was about 45 h.The water content had a greater influence on the expansion and deformation of foundation expansive mudstone.In the unloaded test,the expansion amount increased with the increase of water content,and in the loaded test,the expansion amount decreased first and then increased with the increase of water content,the expansion and deformation of foundation expansive mudstone stabilized when the water content was 23%~25%.Based on the mechanics theory,the physical equations in the elastic mechanics were applied,and the expansion rate was introduced,then the calculation formulas for the expansion amount of foundation expansive mudstone under the combined effect of water content and overburden load and that without overburden load were derived.It was found that when the water content was over 7%,the maximum relative error between the calculation results of formula and test results was 14.87%,thus the formulas can provide theoretical support for the practical engineering.