Research On Key Technology Of Mud-water Balance Shield Construction In Polluted Stratum

In recent years,China's urban rail transit construction has developed rapidly,and the subway construction is in full swing.Among them,the performance of China's subway is particularly prominent.The chemical industry has always played a pivotal role in China's national economic construction.In the chemical,paper,printing,dyeing,tanning,pharmaceutical,electroplating and other industrial clusters,the accumulated pollutants for many years will form a unique contaminated stratum in the region,the soil and groundwater pollution is more serious by sampling and testing the pollution situation in the 100-chemical interval.The main pollutants are: heavy metal arsenic(exceeding 3.76 times),total petroleum hydrocarbons(C6?C9)(exceeding 1.46 times),vinyl chloride(2.6 times),1,2-dichloroethane(34.8 times),chloroform(6.5 times).These pollutants can be absorbed by the human body through contacting and breathing,which brings great harm to construction workers.In the process of subway tunnel crossing the polluted stratum,if the corresponding construction technical measures are not taken,it will bring greater harm to the construction personnel and project quality.This paper takes the Beijing Subway Line 7 line 08 Baiziwan Station-Chemical Station as the engineering background,using on-site investigation,theoretical analysis and laboratory test to carry out research on the key construction technology of mud-water balance shield under shielded stratum conditions.The main research results and research conclusions obtained are as follows:(1)Based on the comprehensive consideration of safety factors,environmental factors and economic factors,the adaptability of the earth pressure balance shield and the mud-water balance shield was compared and analyzed.The mud-water balance shield construction was carried out,and the adaptability of the adopted Mitsubishi mud-water balance shield was evaluated.(2)Combined with the engineering characteristics of the Bai-Hua section,the pollution control measures of the mud-water balance shield construction,the initial technology of the small-radius curve shield,the construction technology of the tunneling area and the mud-water separation technology of the fine-grained formation in Beijing were studied.(3)A real-time monitoring system for mud-water balance shield construction with Chinese operation interface was developed,and the pre-set parameter control range was entered into the system to realize real-time warning of construction parameters.The system was in Beijing Subway Line 7 line 08 mark hundred-chemical interval successful application.(4)Combined with the characteristics of contaminated soil in the area of Bai-Hua,the contaminated soil was treated by incineration and gas phase extraction(SVE).The results show that both incineration and gas phase extraction(SVE)techniques can treat the separated muddy water.Contaminated soil,the treated soil meets the requirements of relevant national regulations,and the environment is not re-contaminated during the treatment.