EXPERIMENTAL STUDIES ON THE WATER BALANCE AND THE ROLE OF PORE PRESSURE IN THE PROCESS OF SLOPE FAILURE

雨水以降雨的形式提供给斜坡的水渗透并储存在土层中。在这些过程中，边坡就会发生破坏。因此，从这个意义上说，边坡破坏现象可以是土层水分平衡问题之一。这是一个以“水平衡”和“孔隙压力”为关键词的实验研究。hiura博士是首席研究员，他通过模型坡度和人工降雨系统进行了研究。共同研究者kaibori博士研究了水砂混合土中孔隙压力的消散过程。所得结果总结如下：(1)识别出两种类型的破坏，一种是发生在坡面径流开始前的流水型破坏，另一种是发生在坡面径流水量恒定后的递进型破坏。(2)在降雨开始后的任意时间间隔内，供水量与降雨穿透土层的体积之比，即体积含水量指数在降雨开始时呈快速上升趋势，随后趋于稳定，与土壤条件和降雨强度无关。(3)坡面运动表现为蠕变变形特征，但与坡面体积含水量和坡面径流水量似乎没有关系。4)实测超孔隙压力为整个土层厚度的1.5倍，但未观察到孔隙压力波动预测边坡破坏的发生。(5)人工破坏时产生的超孔隙压力比自然破坏时产生的超孔隙压力消散更快。6)砂质土与水混合搅拌试验表明，孔隙压力的消散速率与比粉粒细的颗粒比有关。7)对于高浓度混合物（63%体积密度）的振动实验，在振动停止后孔隙压力很快消散。少

Water supplied to the slope in the form of rainfall penetrates and stored in the soil stratum. Slope failure occurs during these processes. So, in this meaning, slope failure phenomena can be one of the problems of water balance in the soil stratum. This is the experimental study whose key words are "water balance "and" pore pressure". Dr.HIURA who is the head investigator executed his study by the model slope and artificial rainfall system. Dr.KAIBORI who is the coinvestigator has examined the dissipation process of pore pressure generated in the mixture of water and sandy soil. Results obtained are summarized below ;1) Two types of failure were recognized : one is the flow type failure which occurs before the runoff from the slope begins and the other is the progressive type which occurs after the quantity of runoff water from the slope becomes constant.2) The index of volumetric water content, which is the ratio of amount of the supplied water to the volume of the rainfall penetrate … More d soil stratum at an arbitrary time interval from the beginning of the rain, shows the fast rise at the beginning and becomes constant afterwards independent of the soil condition and rainfall intensity.3) Surfacial movements of the slope showed the creep deformation characteristics, though the movements seem to have no relation to the volumetric water content and the amount of the runoff water from the slope.4) The measured excess pore pressure showed 1.5 times as much as the thickness of the whole soil stratum, though no fluctuation of pore pressure to predict the occurrence of the slope failure was observed.5) The excess pore pressure, which is produced in case of an artificial slope failure, dissipates faster than that produced in case of natural failure.6) The stirring experiments in use of sandy soil and water mixture have revealed that the dissipation rate of the pore pressure depends on the ratio of grains finer than silt.7) In case of the vivration experiment of highly concentrated mixture (63% of volumetric density) , pore pressure dissipates soon after the vivration has stopped. Less