Study On The Deformation And Fracture Features And The Mechanism Of Stability Level-off About The Kouqiang Huge Deformation Body In Yalong River

A number of large-scale landslides usually undergo the process from stage of deformation and fracture to trigging the formation of landslide. The existing abundant study results have shown: most of researchers studied landslides and collapses what have happened, and less of them studied huge deformation body among which landslides may happen; most of researchers studied deformation from the view of constant speed rheology and accelerating rheology, and less of them studied from the view of decelerating rheology and gradually braking; most of researchers studied the deformation and destruction resulting under ground stress environment, and less of them studied the dynamical features of deformation body under new ground stress environment. There is a Kouqiang huge deformation body in the granite slope of right bank of Yalong River Yagen Second Power Station, the tension deformation and disassembly of rock mass is very serious, and accompanies many new fracture cracks. The depth of the horizontal distribution of tension deformation body is deep from adit, and there are too many boreholes to do water pressure test This huge deformation body has become an important engineering geological problem of power station engineering and problem of stability of high and steep slope, and it is indicated that this deformation body was ever destroyed seriously when it was formed, and it is difficult to find this kind of latent deformation body which has not develop toward landslide. The information of supervision and observation show that the situation of slowly braking and decelerating rheology appears, and the deformation body has been in the stage of stability level-off in long term in the later period of formation of the deformation body.On the basis of knowledge mentioned above, this dissertation studies from various aspects and obtains following results. (1) This dissertation studies the structure and quality features of the Kouqiang huge deformation body, and enriches the contents of geological environment of studied in system engineering geological research area by deeply investigating of the exploration data and analyzing the engineering geological conditions of studied area.(2) The Kouxiang huge deformation body of right bank near dam has the features of large scope, huge size and deep depth; it is difficult to explain with the unloading concept of rock mass. This dissertation realizes that this special geological phenomenon is the key of resolving the important engineering geological problem of right bank near dam of power station, and strives for enriching the research of slope engineering geological work and stability, especially the research contents and methods of rock slope huge deformation body in current.(3) The Kouqiang huge deformation body in right bank can be divided into tensioned and loosened rock mass, strongly tensioned rock mass and tensioned rock mass according to the different tension deformation extents from the outside to the inside. According to the domestic related criterions of hydropower engineering geology, the engineering rock mass grade of the Kouqiang huge deformation body cannot satisfy the related criterions, so this dissertation proposes the classified evaluation methods of tensioned (teared and elevated locally) rock mass, and classify the body grade of tensioned and loose body on the surface of deformation body asâ…¤2, this classified evaluation method will be a beneficial supplement of existing criterions and it can be applied easily in project construction.(4) This dissertation makes the best use of information of exploratory adits and borehole testing, studies the deformation and fracture characteristics of the Kouqiang huge deformation body, and studies the quality variation features of rock mass, determines the strength parameters of deformation body in different zones.(5) This dissertation studies the boundary features of the Kouqiang huge deformation body. It analyzes the boundary of deformation body primarily with the numbers of exploration adits, boreholes and many testing results setting in the Kouqiang huge deformation body, then judges the boundary shape of deformation body by the space distribution and the control effects to boundary forming of weak structure surface, and finally determines the true boundary. This dissertation uses the 3D map embedded quality information of the Kouqiang huge deformation body to display various interior geological information of rock mass.(6) This dissertation studies on the special geologic phenomena of Kouqiang huge deformation body developed inside the granite bank slope in terms of present and historical deformation dynamics, monitoring results, boundary conditions, bottom features, shearing conditions, stress restitution (partial restitution) and so forth. Based on the fact of stable status and the corroborative evidence of plentiful exploration data, and in virtue of stability evaluation on the huge deformation body, the concepts of "Quality Variation of Rock Mass" and "Stress Partial Restitution" are proposed in this dissertation, additionally, based on those two concepts and the process of change of stress state in the slope, this dissertation points out that" the weak surface buring under the river bed", "Stress Partial Restitution" and "Stress concentration" make the deformation slow down gradually are the important reason or mechanism of the Stability Level-off of the deformation body.(7) On this account of the mechanism of stability level-off, it is impossible for the occurrence of instability failure in a certain place of the valley bottom at the right bank of riverbed in the Kouqiang huge deformation body under the current state. Since the surface does not exist a unified bottom slipping surface in tensioned and loosened rock mass, and would not create conditions for overall rapid gliding, it may lead to local instability and may present as retreat-style slump failure. The possible failure modes may happen from a potential sliding free surface located above the river valley. The quantitative analysis of stability indicates the earthquake is a key factor to control the stability of tensioned and loosened rock mass slope.(8) On the basis of ascertaining the most possible shear failure location in slope instability and failure, this dissertation utilizes counter pressure (foreslope pressing foot) engineering processing approach, without performing excavation and deloading to itself but taking appropriate support pattern for the upper slope after pressing foot treatment to guarantee the purpose of slope stability. Materials for pressing foot treatment are principally derived from the discarded materials of dam, tunnel excavation and stock ground mining, so as to maximally avoid the environmental and geological issues due to using a slag pit to dispose the discarded materials. In view of the low-level tensioned rock mass within the mechanism of stability level-off zone under the study of this dissertation, consolidation grouting approach has been put forward in order to speed up the compaction process of the rock mass, decrease the deformation space of the rock mass and improve the general stability of the slope.(9) The study of "Mechanism of Stability Level-off " reveals the nature of stability status of the Kouqiang Huge Deformation Body. The mechanism not only provides scientific basis for decision-making for this project and project treatment measures with a high technical content, but has a high theoretical value and high economic value.