一、前言 不扰动土样通常取自钻孔底部。这一事实本身即为土样扰动的重要原因之一,因为不完善的钻探操作早已使取样土体受到了扰动,即使用最好的取土设备也无法弥补。钻孔不能取得不扰动土样的主要缺陷之一是钻孔内地下水位太低。地下水位低固然易于钻探,而且缩短了钻孔的时间,但是其缺点是在钻孔底部周围的土中产生较大的向上水 First, the preface undisturbed soil samples are usually taken from the bottom of the borehole. This fact by itself is one of the main causes of soil-type disturbances, as imperfect drilling operations have already disturbed the sampling of soils that can not be offset by the use of the best earth-borrowing equipment. One of the major pitfalls that can not be achieved without disturbing the soil sample is that the water table in the borehole is too low. The low groundwater level is easy to drill and shortens the drilling time, but has the disadvantage of generating a large upward mass of water in the soil around the bottom of the borehole