岩溶洞穴制图研究

A Research on Cartographic Designing and Forming of Karst Cave Map-Making

对于溶洞三维空间形态,需要选取二至三种图相组合,构成一定的图型,才能较全面地予以反映。为了选择好恰当的图种,相互搭配组合,就需对各种溶洞图进行深入研究。因此,文中列举出平剖面图、多层剖面图、立面图等多种图的具体运用。编图方法不外乎是依照水平投影或竖直面投影的方法编绘。垂直比例和水平比例一般可以保持相同。为了较完善地表示地下溶洞的整体外貌及其与地表地貌的密切关系,提出此二者相组合的溶洞概貌图。在较广地面表示洞穴分布,提出以地貌类型或分层设色地势作为底层平面的图型。

The author made an on-the-spot investigation and survey of part of karst caves in the karst topographic regions in Guizhou, on the basis of which he analysed the functions of karst plane figures, longitudinal section maps and cross section maps and the map-forming methods according to map-making experience and from the point of 184 贵州地质 1990年第7卷 view of map perception theory. These map types can be divided into two: horizontal iro-jection and vertical projection. A hrizon plane or a vertical section taken as a projection plane shows respectively the elements making up karst cave forms. Generally speaking, in order to show the three-dimentional space forms of karst caves, more than two charts need to be chosen to combine so as to be shown more completely and perceptibly. In general, the vertical scale of chart-making of karst caves needn't be magnified and are kept the same as the horizontal scale. To differentiate a plane section from plane diagrams is to pick out a horizontal plane of certain height in caves, with the tangent line of both the cave wall and the plane as the section line on the plane section map (Fig.2 ) . According to the principles of drawing plane section maps, superimposed plane section maps (Fig.4, Fig.7 ) can be compiled and drawn, which are suitably for showing the forms of skylights and shafts. If there exist double passages in caves that are connected to form closed paths Fig. 3) , it's suitable to choose a vertical section projection. If the cave height, cave wall contour, karst solution and sedimentation form of a local section are to be shown, an additional vertical section map needs making. It should be noted that compiling and drawing a superimposed cross section map by using a cross section map is of a certain depth of vision field and can show a cross section contour and its changes (Fig.5) in a distance p pendicular to the map. The vertical section map and the cross section map are nothing but two special elevation drawings. The drawings which continually show cave wall forms are of depth perception and stereo effect and are an important basis for studying small forms of caves, such as the illustration (Fig.7 ) of cave wall viaducts of the forth high window and to the southern part of the fifth high window. The cave calcium carbonate makes the inner cave take on a splendid sedimentary form, which is suitably to be shown by an elevation drawing so as to give a proximal sense of sight sensation. The vertical section map is surveyed by using theodolite wires, the cross section map is surveyed by using a profile recorder and the elevation drawing is surveyed by using the method of close shot photography. Compiling and making the sketches of the drawing on the basis of the superimposed profile is the best way to keep the position accuracy of sketching contours and tricks and geometric fidelity. In order to fully and visually show the whole appearance of karst caves, vertical section lines are compiled and drawn according to the level projection position of karst caves, on the basis of which the elevation drawing of the cave back is made, and then with the underground karst cave appearance combined with the illustration map of the earthsurface, a preliminary relief map can be drawn (Fig.4, Fig.7 ) by using both level projection and vertical plane projection. The purpose for drawing the map is for readers to have a fully under- (下转147页) (上接184页) standing of the cave appearance and its relationship with the land features. In compiling and drawing the distribution map of cave entrances, a geomorphologi-cal map or a colour-layered topographic map can suitably serve as the base plane. The contour distances of every cave entrance of the map-making region, their arithmetic average value and standard difference figured out according to statistics and the boundary lines of colour layers graded by standard difference. In this way, using contour lines required by map-making can enrich the map contents, increase the readability and have a better map-reading effect.