浅谈堤防公路设计与施工

堤防公路一般在现有堤防项进行修筑，其设计和施工与一般公路既有相同点又存在较大差别。中对堤防公路的设计与施工作一个简单介绍。     

生态环境视角下的江堤变迁：以明清时期皖江江堤为例

明清时期,由于人口增多,安徽沿江地带出现围湖垦殖、与水争地的高峰,沿江圩口基本联成一线。皖江圩田地处沿江洼地,为长江冲积平原,每到夏秋之际,江水暴涨,惟靠一线江堤抵御江水。安徽沿江江堤成为这一地区工农业的重要保障。随着人类不断对沿江洼地的垦殖,在抵御洪灾的过程中,皖江退建堤增多,江堤不断变迁。在江堤变迁的过程中,其对沿江的生物多样性、江面面积和水灾频率次数都带来一定的冲击。     

Field experiment on train-induced embankment vibration responses in seasonally-frozen regions of Daqing, China

The seasonal-frozen layer may have an influence on embankment motion from train-induced vibrations. Based on the field monitoring in a seasonally-frozen region of northeastern China, the effects of the frozen layer on the embankment responses to train-induced vibration were investigated in winter and summer via acceleration time histories and acceleration frequency spectrums. The results show that： （1） Compared to unfrozen soil conditions, the amplitudes of longitudinal and vertical vibrations at the points near the rail were increased, different influences of freight versus high-speed trains are the most evident. （2） With greater distance from the rail, the dominant frequency ranges of embankment with both frozen and unfrozen layers narrowed and shifted to low frequency bands. （3） The predominant frequency of embankment vibration with frozen soil layers shifted to higher frequencies with the increased train speed, although there was little change with unfrozen condition. Layer condition （frozen versus unfrozen） and distance to rail both play important roles in investigating the embankment vibration characteristics and rail transit field monitoring to improve the criterion of the rail construction in seasonally-frozen regions.     

路堤荷载下混凝土芯水泥土搅拌桩工作特性研究

研究目的：研究混凝土芯水泥土搅拌桩在路堤荷载下的荷载传递规律和变形控制机理。创新要点：评价路堤荷载下混凝土芯水泥土搅拌桩的地基处理效果,测量混凝土芯的竖向应力变化规律和复合地基桩士荷载分担特点,并分析填土过程中混凝土芯水泥土搅拌桩复合地基的固结规律。研究方法：通过埋设沉降板、分层沉降管、测斜管、土压力盒、孔隙水压力计以及钢筋应力计,在路堤填筑过程中对混凝土芯水泥土搅拌桩复合地基进行了长期现场试验。重要结论：1．混凝土芯水泥土搅拌桩复合地基的总沉降、工后沉降以及深层水平位移控制效果均较好,优于普通水泥土搅拌桩复合地基：2．混凝土芯水泥土搅拌桩复合地基的桩土应力比以及荷载分担比均大于普通水泥土搅拌桩复合地基,能有效减小土体表面的荷载量,对于控制沉降有一定的效果。3．在路堤这种柔性荷载作用下,混凝土芯水泥土搅拌桩上部会出现一定的负摩擦阻力,存在一个“中性点”。4．混凝土芯水泥土搅拌桩复合地基的固结速率较快,能有效控制由于丰崮结引起的长期沉降。     

A modified creep index and its application to viscoplastic modelling of soft clays

Conventional consolidation tests on reconstituted specimens of numerous natural soft clays show a decreasing of creep index Cae with increasing soil density. Based on all selected and conducted experimental results, a modified creep index Cae＊ defined in double logarithmic plane lge-lgt, was plotted for various clays, from which Cae＊ can be assumed as a constant for different soil densities. Then, the modified creep index was applied to a newly developed elastic viscoplastic model. In this way, the modified creep index Ca＊ can naturally take into account the nonlinear Cae revealing the influence of soil density in the soil assemblies without additional parameters. Finally, the enhanced model was incorporated into the finite element code ABAQUS and used to simulate a consolidation test and a test embankment. The improvement of simulations by the modified creep index was highlighted by comparing simulations using the conventional creep index Cae.