土木工程專業(yè)外文翻譯---土方工程的地基勘察與施工-建筑結(jié)構(gòu)(存儲(chǔ)版)
【正文】 estigations and earthworks. 1. INTRODUCTION The investigation and reuse evaluation of many Irish boulder clay soils presents difficulties for both the geotechnical engineer and the road design engineer. These glacial till or boulder clay soils are mainly of low plasticity and have particle sizes ranging from clay to boulders. Most of our boulder clay soils contain varying proportions of sand, gravel, cobbles and boulders in a clay or silt matrix. The amount of fines governs their behaviour and the silt content makes it very weather susceptible. Moisture contents can be highly variable ranging from as low as 7% for the hard grey black Dublin boulder clay up to 2025% for Midland, SouthWest and NorthWest light grey boulder clay deposits. The ability of boulder clay soils to takein free water is well established and poor planning of earthworks often amplifies this. The fine soil constituents are generally sensitive to small increases in moisture content which often lead to loss in strength and render the soils unsuitable for reuse as engineering fill. Many of our boulder clay soils (especially those with intermediate type silts and fine sand matrix) have been rejected at the selection stage, but good planning shows that they can in fact fulfil specification requirements in terms of paction and strength. The selection process should aim to maximise the use of locally available soils and with careful evaluation it is possible to use or incorporate ‘poor or marginal soils’ within fill areas and embankments. Fill material needs to be placed at a moisture content such that it is neither too wet to be stable and trafficable or too dry to be properly pacted. High moisture content / low strength boulder clay soils can be suitable for use as fill in low height embankments (. 2 to ) but not suitable for trafficking by earthwork plant without using a geotextile separator and granular fill capping layer. Hence, it is vital that the earthworks contractor fully understands the handling properties of the soils, as for many projects this is effectively governed by the trafficability of earthmoving equipment. 2. TRADITIONAL GROUND INVESTIGATION METHODS For road projects, a principal aim of the ground investigation is to classify the suitability of the soils in accordance with Table from Series 600 of the NRA Specification for Road Works (SRW), March 2020. The majority of current ground investigations for road works includes a bination of the following to give the required geotechnical data: ? Trial pits ? Cable percussi
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