原状泥岩膨胀变形试验及计算模型研究

高铁无砟轨道对路基上拱要求极为严格,泥岩地基遇水后将导致路基上拱,进而影响到高速铁路行车的安全性。以兰新高铁一典型路基上拱地段地基泥岩为研究对象,开展了2 cm、4 cm和6 cm共3种不同高度,10 kPa、20 kPa、30 kPa、40 kPa和50 kPa共5种上覆荷载,以及5.5%、7.5%、9.5%、11.5%和13.5%共5种含水率下的膨胀变形试验。试验结果表明:原状泥岩膨胀量随吸水率增大而增大;上覆荷载对膨胀量起抑制作用,当荷载较小时,抑制作用较弱,荷载较大时抑制作用较强;原状泥岩高度越大,膨胀量越大,且膨胀量与高度不成比例增加;建立了综合考虑泥岩上覆荷载、含水率和高度耦合作用下膨胀量计算模型,模型计算结果与实测数据吻合较好,具有一定推广性。

Study on Expansion Deformation Test and Calculation Model of Undisturbed Mudstone

The high-speed railway ballastless track has strict requirements on the upper arch of the roadbed. When the mudstone foundation meets the water, it will cause the roadbed to the arch, which in turn affects the safety of the high-speed railway. The deformation of undisturbed Mudstoneunder the second line of Lanzhou to Xinjiang Railway was studied. Overloadings of five levels such as 10 kPa,20 kPa,30 kPa,40 kPa and 50 kPa were applied to three different thickness 2 cm,4 cm and 6 cm,with the water content of 5.5%,7.5%,9.5%,11.5% and 13.5% respectively in order to measure the deformation of undisturbed expansive soil. The test results show that the expansion of the undisturbed Mudstoneincreases with the increase of water absorption. The overlying load would have a restraining effect for expansion of undisturbed expansive soil. When the load was small, the inhibitory effect was weak. When the load was large, the inhibitory effect was stronger. When the thickness of undisturbed Mudstone was bigger, the expansion was larger. And the expansion and thickness were not proportional to the increase. When the thickness was constant, the formula was obtained of water content and overburden load for expansion of undisturbed expansive soil. According to the parameters of the formula, the calculation model of Mudstone under the coupling action of water content, overlying load and thickness was established. The calculated results agreed well with the measured data, which provides some theoretical support for the project construction of the ballastless track on the high-speed railway in the future.