| Soft-hard-alternated layered rock is a complex composite dike featured by its specificity and complexity in its rock mass structure, mechanical parameters of rock, etc. When such a kind of rock is used as the dam foundation rock for high concrete gravity dam, the applying of existing rock structure classification schemes, dereferencing parameters of rock mass mechanics and rock mass quality evaluation system would present a certain number of limitations on the evaluation of engineering geological characteristics of soft-hard-alternated layered rock. Therefore, it would be critical when the evaluation indicators can be obtained to accurately reflect the engineering geological characteristics of soft-hard-alternated layered rock, which can be used to accurately assess the rock mass to address the dam foundation rock for high concrete gravity dam.While I studied for my doctor degree, along with my in-depth research on soft-hard-alternated layered rock, I came to realize that soft-hard-alternated layered rock should include soft-hard-alternated deposition-stratified rock, soft-hard-alternated stratified parablastesis and a variety of soft-hard-alternated deposition-like rock mass and so on. Besides, the comprehensive deformation parameters of soft-hard-alternated layered rock could be one aspect of the mechanical parameters only, which would be far from enough for the comprehensive and accurate evaluation of integrated engineering geological characteristics of soft-hard-alternated layered rock. So, the deeper research on soft-hard-alternated layered rock is quite necessary. Applying the soft-hard-alternated layered rock of the Jinsha River Guanyinyan Hydropower Station and Ahai Hydropower Station as the prototype for the said research, the present thesis has studied the structural features of soft-hard-alternated deposition-stratified rock and soft-hard-alternated stratified parablastesis, improved the layered rock structure classification schemes and proposed that the developmental situation of the bedding level and other structural profiles should be analyzed when holding the layered rock structure classification which should be considered based on the further more developmental conditions. For the stratified parablastesis, the metamorphism reforming the original structure of layered rock should be considered, i.e., when the late metamorphism strengthens or weakens the original structure of soft-hard-alternated layered rock, the use of structural development for the classification of rock structure would be presented with limitations and those indicators that can reflect the inherent engineering properties of rock should be included, such as longitudinal velocity of rock mass, boring-core RQD value and other structure types for comprehensive classification of stratified parablastesis.Anisotropy is a prominent feature of soft-hard-alternated layered rock whose comprehensive mechanical parameters include comprehensive deformation parameters and integrated intensity parameters. In the circumstances having the researched prototype reasonably generalized, the theoretical solution of the comprehensive deformation parameters for soft-hard-alternated layered rock at any angle have been derived, the integrated intensity parameters for soft-hard-alternated layered rock under different strength of stress have been studied and the method for calculating comprehensive strength parameters of soft-hard-alternated layered rock has been improve. For the soft-hard-alternated layered rock having thicker single stratum (such as the Dam Foundation Rock of Guanyinyan Hydropower Station), the conventional rock situ testing of mechanical parameters can only provide mechanical parameters for a single stratum. In order to obtain the experimental values of the comprehensive deformation parameters for the soft-hard-alternated layered rock, the situ testing of comprehensive deformation modulus for soft-hard-alternated layered rock has been designed whose pressure plate is a rectangular plate of 200cm×50cm. The comprehensive deformation modulus for soft-hard-alternated layered rock has been obtained directly by the situ deformation testing of large size and high load in respect to multi- stratum rock. For the soft-hard-alternated layered rock having thin stratum (such as the Dam Foundation Rock of Ahai Hydropower Station), the differences and similarities between the conventional deformation experiments and the large size and high load deformation testing results have been compared. Regarding the integrated intensity parameters for soft-hard-alternated layered rock, those intensity parameters for the rock mass of each single layer has been obtained firstly and then, under the occurrence of rock mass of the dam foundation and its future load-carrying capability, the design formulas for the integrated intensity parameters of the soft-hard-alternated layered rock have been used to calculate out the related comprehensive intensity parameters.The analysis of engineering geological characteristics of soft-hard-alternated layered rock has determined that the rock structure and the comprehensive mechanical parameters of rock are two core elements for the evaluation of the merits of the related engineering geological characteristics. The situ testing is the best way for obtaining comprehensive mechanical parameters of soft-hard-alternated layered rock, but the experiment on comprehensive intensity parameters can not be carried out currently because the situ deformation testing of comprehensive mechanical parameters for soft-hard-alternated layered rock is too large a scale. Therefore, for soft-hard-alternated layered rock, the establishment of other relationships is the better way for fully obtaining mechanical parameters of rock mass of dam foundation. Finally, the present thesis has studied to some certain extent the dereferencing method for comprehensive mechanical parameters of soft-hard-alternated layered rock. Using the present research findings in relation to the rock structure of soft-hard-alternated layered rock, the comprehensive mechanical parameters and the evaluation of rock mass, the best construction base surfaces of Guanyinyan Hydropower Station have been successfully chosen and the positions of construction base surfaces of Ahai Hydropower Station riverbed dam foundation has been optimized. Therefore, the present research on the soft-hard-alternated layered rock is in line with the related engineering geological characteristics, providing not only theoretical significance but also practical value. |
PDF Full Text Request