Laos Sanakham Hydropower Stations Deep Silty Sand Layer Design And Research Of Large Caisson

As a kind of foundation pit retaining structure of open caisson,and compared with the large excavation can reduce earthwork excavation quantities,save engineering investment.Engineering land saving,and can effectively reduce the influence on surrounding buildings and the surrounding environment and destruction.In the field of hydropower engineering,the layout of large caisson can also be combined with the building layout,do it in the permanent union,can effectively reduce the engineering hub building size,thereby reducing the project cost.In addition,in the process of open caisson application due to the understanding of the characteristics of soil around the open caisson is insufficient,lead to uneven subsidence in the process of sinking of open caisson,sink,tilt and other issues,in order to solve these problems,to ensure smooth application in engineering of open caisson,and combined with the features of soil around the open caisson study of design and construction of open caisson becomes crucial.This article,which is based on Laos Sanakham open caisson design of hydropower stations,combined with Laos Sanakham hydropower station dam site river special characteristics of the deep silty sand layer,using analytic method and finite element theory of open caisson foundation done further research in the application of silty sand stratum,Main contents and conclusions summarized as follows:(1)Of open caisson in the background of the engineering application are introduced,than choose the guide wall scheme and the open caisson plan two,starting from the geological characteristics of silty sand stratum,both consider the scheme,technical feasibility and economical analysis to determine the use of open caisson as longitudinal cofferdam foundation scheme;(2)By using the proposed method of parsing the global stability of the open caisson under the most unfavorable conditions,and the wall toe stress calculation and analysis,the.calculation results show that the proposed open caisson foundation stability and the whole wall toe stress can satisfy the requirements of the current specification;(3)Subsidence calculation results show that:in the process of sinking of open caisson,the sinking of the most important,first should try to control the subsidence rate,keep it steady.In the late open caisson sinking,sinking force was sinking faster pace of increase in resistance;(4)under the condition of the most unfavorable conditions,this project is applied to two kinds of shape of open caisson,respectively,the finite element analysis,and according to the results of the stress analysis and calculation of two kinds of size of open caisson has carried on the reinforcement calculation,the first quarter or above of the open caisson reinforcement generally for the minimum reinforcement ratio of reinforcement;(5)According to the geology of silty sand stratum lithology,the open caisson in that may occur in the sinking process of tilt,the problem such as sudden sinking,combining the application of open caisson in the existing hydropower station,gives some prevention measures can be used for reference.Based on analysis and study of open caisson in silty sand layer design,to ensure the smooth construction of open caisson in silty sand stratum has important guiding significance,main body for Sanakham hydropower station project smooth implementation also plays an important role.And for such wide valley,big flow,silty sand layer of the open caisson design for reference.