Altered Rock Zone Deformation Modulus Research In Meng Digou Hydropower Station

In water conservancy and hydropower project construction, rock mass deformation modulusis importantmechanical parameters for dam design and dam foundation’s deformation stability analysis,primarilyrelated to lithology, size, weathering unloading, integrity and their stress environmental factors, but due to the inhomogeneity of rock mass, to make itself with uncertainty, discontinuity, not stability and other features, which lesds to value of rock mass deformation modulus is very difficult. Therefore, the value of the modulus of the rock mass deformation research is of great significance.This article is based on the Meng Digou hydropower station dam area regional geological conditions and altered rocks zone engineering geological characteristics investigation and analysis, first of all, according to the large deformation test value and the acoustic test value, for different classes of rock mass which is complex combination by soft and hard rock mass(“mutual layered”), use of traditional Vp—E0 correlation analysis, the arithmetic average method to calculate the deformation modulus of alteration rock zone. Then, using four kinds of mathematical methods: the weighted average method, AHP, unascertained mathematical method and partial least squares regression and neural network analysis correlation method, to study on deformation modulus value for dam foundation, and ultimately determine the recommend value of deformation modulus in the dam foundation alteration zones and optimal value method. The main research results are as follows:(1)Rigid bearing plate test not only Cost high, but also spends long period, it is impossible to do a lot of deformation testin the region.On the contrary, acoustic testing of the low cost and short timeconsume, can do a lot of acoustic tests in the region. In this paper, using nonlinear regression method to analysis acoustic test and deformation test data in dam foundation rock mass, establish the correlationformula of Vp-E0, then using the acoustic testdata to thrust reverser the deformation modulus where without making deformation test. Using this method saves the cost of doing bearing plate test and time costs, is an effective means to rapid quantitative analysismechanical properties of complex combinations alternating hard and soft rock mass.(2)Unascertained mathematical method is devoted to dealing with various uncertain information mathematical methods. The proposed Meng Digou hydropower station dam foundation intensive altered rock zone has the uncertainty of complicated geological conditions(altered rocks width, the percentage and different degree of alteration) and the experimental error. Therefore, this article using unascertained mathematical method to study on altered rocks znoe deformation modulus is feasible.(3)The unascertained mathematical method results show that, intensive altered rock zone ACZ01, ACZ02 deformation modulus when ranging respectively between at 4 ~ 5GPa, 17 ~ 18 GPa,with maximum reliability, guaranteed rate up to 91.56%, 83.81%. Using the traditional VP-E0 correlation analysis method to calculate ACZ01, ACZ02 deformation modulus respectively at 6.94 GPa, 18.03 GPa, the ensure rate only 64.29%, 71.59%, thus, compared to traditional methods the unascertained mathematical method is more reasonable and reliable for deformation modulus value in this kind ofrock zone which combination by soft and hard rock mass(“mutual layered”).Because clay alteration leadingto altered intensive altered rock zone ACZ01, ACZ02 rock mass deformation modulus respectively reduced by 82.70% ~ 86.16%, 37.72% ~ 41.18%, indicating that alteration has a greater impact on the rock mass deformation properties.(4)Although unascertained mathematical calculation method is much complex, but the results are stable, fine, the value of each data segment you can found the corresponding confidence level, and quickly find the maximum value of the confidence level and the assurance rate. This study for the geological conditions differences and uncertainty in intensive altered rock zone, using unascertained mathematical method which usually deal with all kinds of uncertain information to research on deformation modulus,It is an exploring in the field of engineering geology. It is worth looking forward to further application in the field of geological engineering.(5)Partial least squares regression and neural network associates model combine the superiority of the partial least squares regression dealing with multiple correlation among variables with artificial neural network processing variables nonlinear problem. Making the input of artificial neural network dimensionality reduction, short calculation time and increase stability. Examples show that the association model predicted value with fast convergence rate, error is small, and compared with the measured data of a good fit. However, the calculation process is complex, multi-frequency operation, the determining factors and various factors relationship is complexity. It is not recommended as a reasonable calculation way for altered rocks deformation modulus. But when dam area part of rock mass deformation features’ s qualitative and quantitative analysis encounter the contradictions, the method can be used as a quantitative analysis method of review.(6)when calculation the dam area of a single altered rock deformation modulus value, the best approach is VP-E0 correlation analysis method, which is based on large-scale deformation test, only the acoustic dates can rapid quantitative determination of deformation modulus of rock. For calculations the dam area on the right bank intensive altered rock zone ACZ01-ACZ05 deformation modulus, the optimal value of the method is unascertained mathematical method, the results of this method is more reasonable, safety than other methods, and can make the engineering stability with high reliability.