Research on Geologic Control of Slope Movements --- Analysis of Lithology and Geologic Structure of Basement Rocks

我们主要研究了近畿和四国地区白垩纪至新近纪地层的斜坡运动，例如新近纪的科比群和北丹群，以及白垩纪至古近纪的四万十带。利用航片图像分析方法，对上述特定地区的斜坡运动进行了大量的地貌、地质资料的测量和分析。特别是阐明了斜坡运动与基岩岩性和地质构造的关系。斜坡移动是指斜坡上物质的各种移动现象，包括滑坡。以下地质和地貌因素通常被认为是斜坡移动的产生因素。(1)许多大规模的斜坡运动通常发生在细碎屑沉积物中，如泥岩或细凝灰岩。这就是所谓的岩性控制。(2)岩体主要由基底岩的碎屑和土组成， ...更多信息 第二乐章。另一方面，为了修建道路，人工削坡又会产生新的边坡运动。(3)滑动面通常含有丰富的蒙脱石、伊利石、蒙脱石等粘土矿物，其形成与地下水的作用密切相关。丘陵山区地下水流条件分析是一个难点。(4)许多滑动体沿着基底岩层的顺层平原倾向一侧运动。这就是所谓的“Nagareban”构造类型，表现出典型的构造控制作用。另一方面，少量的斜坡运动，即“Ukeban”型，沿沿着顺层平原的相对侧滑动。(5)斜坡运动的发展并不总是与断层有关。然而，剧烈的构造运动却普遍导致了岩石的风化破裂。这对边坡运动的产生有很大的影响。(6)斜坡运动多发生在特定坡角的斜坡上，即新近系地层10 - 15，前白垩系地层25。这些角度与没有坡移的斜坡相比是很小的，然后指出它们的出现形成梯度斜坡。(7)坡移区由于水资源丰富，常被用作稻田或农场。少

We have mainly investigated slope movements of Cretaceous to Neogene formations in Kinki and Shikoku areas, for example the Kobe Group and the Hokutan Group of Neogene age, and the Shimanto Belt of Cretaceous to Paleogene age. By means of image analysis of aerophotos, we have measured and analyzed many geomorphological and geological data of slope movements in the specific areas mentioned above. Particularly, we made clear the relationship between slope movements and lithology and/or geologic structure of basement rocks. The term "slope movement" means all kinds of moving phenomena of materials found on slopes, including landslides.The following geologic and geomorphologic factors are commonly pointed out as the generating factors of slope movements. (1) Many large-scale slope movements usually occur in fine clastic sediments, such as mudstone or fine tuff. This is called the lithological control. (2) The masses are mainly composed of debris and soil derived from basement rocks, and sh … More ow the secondary movement. On the other hand, new slope movements occur by artificial cutting of Slopes in order to construction of roads. (3) Generally, a sliding surface includes abundant clay minerals, such as montmorillonite, illite and chlorite, and its formation is closely connected with action of groundwater. It is difficult to analyze flow conditions of groundwater in hilly and mountain areas. (4) Many sliding masses move along the dip direction side of bedding plains of basement rocks. This is called the "Nagareban' structure type, and show the typical structural control. On the other hand, a small number of slope movements, which belong-the "Ukeban type, slide along the opposite side of the bedding plains. (5) The development of slope movements is not always concerned with faults. However, remarkable tectonic movements widely brought about weathering and fracture of rocks. This gave great influence to generation of slope movements. (6) A large number of slope movements occur on slopes with specific slope angle, namely 10ﾟ-15ﾟ in the Neogene formations and 25ﾟ-30ﾟ in precretaceous formations. These angles are small compared with slopes without slope movements, and then it is pointed out that their occurrences form gradient slopes. (7) The slope movement areas are often used as rice field or farms, because of abundant water. Less