Many clay railway embankments in the UK are well over 100 years old, and now suffer from a range of stability and serviceability problems. A common means of remediating earthworks that have either suffered, or are assessed as being at risk of, deep-seated slope failure is to install a row of discrete piles along the mid-slope. This paper presents field data from a 9 m high, pile-stabilised embankment at Mill Hill, north London. Initial pore water pressure measurements had shown that the trees present on the earthwork maintained low pore water pressures during winter; thus the trees were left in place after piling to aid stability. The piles initially bent upslope, as a result of inward shrinkage of the embankment over a period of dry weather, before then being loaded by shallower downslope movements of the clay. Later cycles of seasonal movement caused a small but gradual ratcheting upward of pile bending moments. The largest bending moments measured over 6 years of monitoring were those resulting from the initial inward shrinkage of embankment, which reached about 25% of the design capacity of the piles. At the end of the monitoring period, the measured bending moments resulting from shallower downslope ground movements were about 20% of the pile design capacity.

中文翻译：

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用于稳定树木覆盖的铁路路堤的离散桩的性能

英国的许多粘土铁路路堤已有100多年的历史，现在遭受一系列稳定性和可服务性问题的困扰。修复遭受深坡破坏或有深坡破坏风险的土方工程的一种常见方法是在中坡上安装一排离散的桩。本文介绍了伦敦北部米尔山9 m高，桩稳定路堤的现场数据。最初的孔隙水压力测量结果显示，土方树木在冬季保持了较低的孔隙水压力。因此，树木在打桩后留在原地以提高稳定性。在一段干燥的天气里，由于路堤向内收缩，这些桩起初弯曲了上坡，然后才由粘土的较浅的下坡运动加载。后来的季节性运动周期导致桩弯矩向上出现小但逐渐的棘轮运动。在监测的6年中测得的最大弯矩是路堤初始向内收缩所产生的弯矩，该弯矩达到了桩的设计承载力的25％。在监测期结束时，测得的由较浅的下坡地面运动引起的弯矩约为桩设计能力的20％。