Application Research On Ground Safety Inspection And Permeable Anti-scour Wall About Beijuma River Culvert Engineering

Beijuma River culvert engineering is a large river crossing structure on the Mid-route of South-to-North Water Transfer Project for passing through Beijuma River,and it is the first river crossing culvert of Beijing section.Since putting into operation in 2008,the culvert has conveyed water safely for 8 years.After the engineering is completed,the uncontrolled sand mining in river channel leads to continuous large-scale sandpits,some of which are more than 30 m deep and just 130 m from the culvert.The sandpits destroyed the river equilibrium,and the slope instability of sandpits would couse upstream retrogressive erosion under the action of hydrodynamic shear stress of flood,which impairs the structural safety of the culvert.Due to the impact of the downstream sandpits,the Beijuma River culvert engineering faced the dangerous condition of structure exposure during the “7.21” Beijing rainstorm flood in 2012.After the emergency rescue,the culvert maintained normal operation situation,however the dowmstream river bed scoured deep to 3~5m which may cause disturbance to the culvert foundation.The downstream sandpits is still seriously threatening the culvert s afety,therefore,it is necessary to inspect the safety of culvert foundation,recheck the culvert structure under current situation to determine the safety of the engineering structure,and establish protective reinforcement scheme according to the sandpit situation nearby the culvert.This paper focuses on Beijuma River culvert engineering,summarizes the results of ground safety inspection and protective analysis in the process of engineering design,and studies the method of groud safety inspection and the reinforcement scheme while river crossing structure facing the risk of retrogressive erosion.The main content of this paper includes:(1)The method of ground safety inspection and the analysis of inspection results.Comparing method of traditional in-situ inspection with geophysical exploration methods such as geological radar and considering the condition of culvert foundation,this paper chooses the reasonable method of ground safety inspection.Though analyzing the results of different inspection methods,this paper determines the safety situation of culvert foundation.(2)Study on protective reinforcement scheme of culvert.By rechecking the culvert structure under current situation and comparing protective reinforcement schemes,this paper provides the basis for engineering general scheme and engineering layout.(3)Analysis of anti-scour wall structure and study on section form.This paper determines the scouring line elevation of anti-scour wall according to the analysis of river scouring,analyzes and calculates the structure of anti-scour wall to provide a basis for determining the structure size,and chooses the reasonable section form of anti-scour wall by comparing the difficulty of construction and investment.(4)Study on the construction method of anti-scour wall.This paper discusses the construction methods and control points of anti-scour wall.At present,the river crossing structures have increased as China's infrastructure construction develops rapidly.At the same time,the uncontrolled sand mining in river channel leads to more and more sandpits which bring the structural safety a growing threat.This research about Beijuma river culvert engineering will provide reference for the ground safety inspection and protective reinforcement scheme of future river crossing structures.