Earthquake resistant reliable design on agricultural hydraulic structures.

首先，利用井下波传播技术和折射波传播技术，对硅藻泥岩坝址进行了纵波和横波速度测量，估算了坝址处的现场速度分布。由井下法和折射法得到的压缩波速度随深度线性增加，而横波速度与深度的1/6-1/7次方成正比增加，这与路堤上测得的速度分布不同。其次，还进行了微震观测，以预测同一地点的特征频率。3.为了研究小应变区的变形特征，对垂直和水平方向制备的具有力学各向异性的硅藻质泥岩柱状试件进行了三轴压缩和动力试验。得到的结果如下：(1)应变水平越高的试件表现出越大的各向异性，反映在水平与垂直杨氏模数之比上。(2)动态试验结果表明，即使在应变水平为10^-6的情况下，竖直方向的杨氏模数也存在一定程度的应变相关性。最后，利用地震学极值理论得到的上述场地的年最大加速度上限分布，进行了地震危险性分析。结果表明，在100年内预计的加速度为160伽耳，与目前设计的地面加速度相当，而上限加速度约为450伽耳，这在抗震设计中是必须考虑的。

Firstly, measurements of compressive and shear wave velocities are carried out by downhole and refraction wave propagation techniques at dam site composed of Diatomaceous mudstone to estimate the distributions of in situ velocities. The compressive wave velocities obtained from both downhole and refraction methods increase linearly with depth, whereas the shear wave velocities increase in proportion to a function of the power of 1/6-1/7 of depth, which is different from the distribution of velocities measured at an embankment.Secondly, observations of micro tremor are also conducted to anticipate the eigen frequency at same site. The predominant frequency observed is 0.3Hz, so that the depth of suface deposit is estimated about 400m using above-mentioned distributions of shear wave velocities.Thirdly, to investigate the deformation characteristics in small strain region, both triaxial compression (UU) and dynamic tests are performed in cylindrical specimens of Diatomaceous mudstone prepared in vertical and horizontal directions with mechanical anisotropy. The results obtained are as follows :(1) Specimens with the higher strain level exhibit the greater anisotropy as reflected by the ratio between the horizontal to vertical Young's moduli.(2) The dynamic test results indicate that the strain dependency of Young's modulus in vertical direction exists to some degree even at 10^<-6> strain level.Finally, the seismic risk analysis is performed employing the distribution of annual maximum acceleration with an upper bound limit at above-mentioned site, obtained from a theory of extremes using seismological data. As a result, it is shown that the acceleration value expected during 100 years is 160gal, which is about the same as the present design ground acceleration, whereas the upper limit acceleration value is about 450gal ; this must be taken into account in the eartquake resistant design.