岩质滑坡的时间预报与水力启动模型

摘  要  岩质滑坡发生时间的适时超前预报是一个世界性难题，之所以长期不得其解，主要是缺乏对滑坡成生机理的明晰认识和未建立正确的量化模型。本文根据我国长江三峡工程库岸和西南山区积累的大量滑坡实例调查资料并参考国外的一些研究成果，排除了地形控制论与地层控制论观点，阐明了滑坡形成的必要条件是斜坡具有易滑结构；滑坡发生的充分条件是有一定强度的诱发因素作用。故而诱发因素的动态变化对滑坡发生的时间具决定意义。
鉴于地下水诱发的岩质滑坡分布最广，为建立正确的水力启动模型，本文归纳了近代典型岩质滑坡的主要特征：（1）滑面是导水性差异最大的贯通面；（2）滑体长度大而厚度小，长厚比多在20左右；（3）滑坡前缘段先启动；（4）临滑前在前缘段有渗水、冒水或喷水现象；（5）出水宽度之和远小于前缘段总宽度。根据这些特征和水力学、水文地质学的成熟理论指出jennings（1970）等人提出的岩质斜坡稳定性模型存在下列问题：（1）未表明贯通面上岩体重力分布状况；（2）空隙水压力的分布特征与前述滑坡现象和水力学原理相悖；（3）未考虑通水率问题。然后，本文按顺向坡中的易滑超倾坡和椅状坡两个类型建立了斜坡稳定性模型和滑坡水力启动临界值（基本）计算公式。提出潜滑面的综合内摩擦角和通水率的确定方法：（1）滑坡反算；（2）对无水压滑坡滑面倾角和渗水边坡通水率进行观测统计；（3）剪切试验和简易水文地质试验；（4）物探方法。
本文还讨论了新模型的实用意义和应用范围，并对解决这类复杂地质灾害问题的研究途径发表了作者的认识，强调了积累经验的重要性。

MODEL OF HYDRODYNAMIC START-UP FOR PREDICTION OF ROCK LANDSLIDE

The paper attempts to  address a worldwide difficult problem. This problem is how to predict the time of happening landslide. There is no solution yet because of the lack of clear recognition of mechanism about landside and no correct quantitative model to be set up. Accordingly, this paper is based on the geological condition, landslide examples, and external data at the Three Gorge project's bank slopes and southwest mountains, as well as experiences aboard.  It  demonstrates the necessary and full condition of landslide happening. So, this paper eliminates the terrain control theory and stratigraphic control theory for causing landslide.  The paper elucidated that the necessary conditions of landslide is a slope that has easily slipping structure and the full conditions of landslide is the effect of inducing factors.  So the dynamic variation of inducing factors is decisive for the time of happening landslide. 
Whereas rock-landslides are the most widely distributed.  They  are induced by underground water. In order to set up a correct water-starting model,  the paper sums up  the recent theories of typical rock landslide characters as follows: (1) The sliding face is the through penetrative discontinuities with the most difference of water transmissibility; (2) The landslide body's length is bigger than its thickness. The ration of the length to the thickness is about 20;  (3) The front of  landslide is starting early; (4) There is the phenomena  of water seepage or water sprinkling in the front of slope  body before the occurrence of sliding;  (5) The sum of effluent water width on the slope is much smaller than the total width of the front of landslide body.  Further more, the paper applies the hydraulics and hydrogeology theory to pointing out the following problems  associated with a rock stability model proposed by others in 1970.  It is found that  (1) The old model didn't point out conditions of the distribution of the weight of rock over through the penetrative discontinuities; (2) The distribution characters of crack water pressure in the old model is against the  observed landslide phenomena  and hydraulics theory: (3) The old model didn't considered the percentage of going through infiltration water.  Finally, the paper sets up a new slope stability model  and critical value calculation equation of water-start landslide.  The model and the equation are formulated according to easily slip over dip slope and chair-shape slope characters.  Then, it brings   forward the method  on how to acquire parameters of the combined internal friction angle and the percentage of going through infiltration water as follows: (1) The back-calculation parameters of landslide; (2) The method of observation and statistic about the dip angle of slip penetrative discontinuities without hydraulic pressure and  the percentage of going through water; (3) The experiment of the shearing and simple hydrogeology; (4) The method of geophysical exploration.