The Application And Research Of The Deep Foundation Pit’s Supporting Technology In One Thermal Power Plant’s Dumper Chamber

The process of urbanization in China has gradually accelerated in recent years,and people’s requirements for building space have become higher and higher,which has led to the continuous increase in the height and depth of buildings,and the corresponding depth of foundation pits.The requirements for the functions and types of the foundation pit support systems are also becoming more and more diversified.Yet the underground environment is relatively complicated,and it is very important to ensure the safety of the foundation pit and the surrounding environment during the construction of the building.Especially for special engineering geology,it is necessary to fully consider the engineering geological conditions and the site environment.Therefore,it has become an important direction of deep foundation pit engineering research to select reasonable supporting structure according to the characteristics of foundation pit engineering,as well as waterproof and dewatering construction monitoring and so on.The main research work of this paper is as follows.(1)、The types and calculation theory of deep foundation pit support are introduced.This paper takes the deep foundation pit support project of a thermal power plant dumper room in a coal mine as an example,and analyzes the surrounding environment and geological data of the second phase of the thermal power plant’s foundation pit in detail,It can provide the basis for calculating the supporting structure of deep foundation pit.(2)、 According to the factors such as excavation depth,service life and damage consequence,the safety grade of foundation pit support is determined.Carries out a comprehensive analysis of the requirements for safety levels,cost,construction difficulty,and engineering geology of various supporting structure forms,and preliminarily determines four foundation pit supporting schemes.Option one is concrete + cast-in-place pile + steel support,option two is underground diaphragm wall support,option three is concrete slope protection +cast-in-place pile + pre-stressed anchor support,and option four is grading + cast-in-place pile+ pre-stressed anchor rod support.(3)、Using multi-objective fuzzy decision-making theory to determine the weight set of each factor,and carry out the consistency test.Through the fuzzy comprehensive evaluation of the four schemes,to calculate the respective comprehensive evaluation values,and finally the scheme one is determined as the optimal scheme.concrete + cast-in-place pile + steel support,(4)、the specific construction plan and monitoring plan are designed according to the project site conditions,and detailed construction technical requirements and emergency measures are given.(5)、The Safety Monitoring Scheme of foundation pit is put forward and implemented.Through the analysis of the horizontal and vertical displacement rate and total amount of the top of the supporting structure monitored during the construction process,the horizontal displacement rate and total amount of the deep soil layer,and the horizontal displacement change rate and total amount of the column,it is found that,all kinds of data did not reach the early warning value,and meet the support requirements,which provided strong support for the correctness of the optimal method and results of the support plan.It can provide reference for the subsequent design and construction of similar foundation pit supporting projects.