土木工程专业外文翻译---土方工程的地基勘察与施工-建筑结构(编辑修改稿)

土木工程专业外文翻译---土方工程的地基勘察与施工-建筑结构(编辑修改稿)内容摘要：

ptimum MC)  Remoulded undrained shear strength A number of key factors should be borne in mind when scheduling laboratory testing:  Compaction / CBR / MCV tests are carried out on 20mm size material.  Moisture content values should relate to 20mm size material to provide a valid parison.  Pore pressures are not taken into account during paction and may vary considerably between laboratory and field.  Preparation methods for soil testing must be clearly stipulated and agreed with the designated laboratory. Great care must be taken when determining moisture content of boulder clay soils. Ideally, the moisture content should be related to the particle size and have a corresponding grading analysis for direct parison, although this is not always practical. In the majority of cases, the MCV when used with paction data is considered to offer the best method of establishing (and checking) the suitability characteristics of a boulder clay soil. MCV testing during trial pitting is strongly remended as it provides a rapid assessment of the soil suitability directly after excavation. MCV calibration can then be carried out in the laboratory at various moisture content increments. Sample disturbance can occur during transportation to the laboratory and this can have a significant impact on the resultant MCV’s. IGSL has found large discrepancies when performing MCV’s in the field on low plasticity boulder clays with those carried out later in the laboratory (2 to 7 days). Many of the aforementioned low plasticity boulder clay soils exhibit time dependant behaviour with significantly different MCV’s recorded at a later date – increased values can be due to the drainage of the material following sampling, transportation and storage while dilatancy and migration of water from granular lenses can lead to deterioration and lower values. This type of information is important to both the designer and earthworks contractor as it provides an opportunity to understand the properties of the soils when tested as outlined above. It can also illustrate the advantages of predraining in some instances. With mixed soils, face excavation may be necessary to accelerate drainage works. CBR testing of boulder clay soils also needs careful consideration, mainly with the preparation method employed. Design engineers need to be aware of this, as it can have an order of magnitude difference in results. Static paction of boulder clay soils is advised as paction with the or rammer often leads to high excess pore pressures being genera。