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根据南京长江大桥、三桥、四桥的地质钻孔资料,绘制南京段长江古河槽地质剖面示意图。对拟建南京长江四桥附近的四个钻孔进行了采样分析,从钻孔沉积物样品的14C年代及阶地形成时间,可以判断,南京段约-60m~-90m的深槽为末次盛冰期时的长江河槽。钻孔揭示,南京段长江古河槽狭窄陡峭,呈V型,在南京长江大桥附近形成局部深切。根据长江三桥、长江大桥附近古深槽断面形态及底部沉积物颗粒级配,选用沙莫夫公式、河海大学公式等,计算了末次盛冰期时河槽底部的泥沙起动流速及断面平均流速。根据流量—流速—过水断面之间的关系式,计算得出末次盛冰期时长江的流量约为12000~16000m3/s。
According to the geological drilling data of the Nanjing Yangtze River Bridge, the Third Bridge and the Fourth Bridge, the sketch map of the geological section of the ancient river fluvium in Nanjing section is drawn. The sampling and analysis of the four drilled holes near the proposed fourth bridge of the Nanjing Yangtze River are carried out. According to the 14C dating of the borehole sediments and the terrace formation time, it can be concluded that the deep groove of about -60m ~ -90m in Nanjing section is the last glacial When the Yangtze River channel. Drilling revealed that the Nanjing section of the ancient river fluvial narrow steep, was V-shaped, formed near the Yangtze River in Nanjing, the local deep. According to the shape of the section of Gu-Shen-Tau near the Yangtze River Bridge and the Yangtze River Bridge and the grain size distribution of the bottom sediment, Shamov formula and Hohai University formula were used to calculate the sediment-flow-starting velocity and mean velocity . According to the relationship between flow rate, flow rate and cross section, the flow of the Yangtze River at the last ice age is calculated to be about 12000-16000m3 / s.