Study Of Groundwater Features Of Jiaozhouwan Subsea Tunnel In Qingdao

Groundwater has a significant influence on blocking and drainage system of tunnels. Three main features of groundwater of subsea tunnel are water pressure of surrounding rocks'pores, water percolation capacity of surrounding rocks and chemical nature of water percolation of surrounding rocks.This paper is based on the project of the QingDao subsea tunnel. Through field test, the author studied the three questions. The knowledge of groundwater characteristics can provide theoretical basis for the design and construction of future subsea tunnels, and also provides valuable reference for the maintenance in tunnels'operation after open to traffic. The following studies are included:1. High pressure water outburst is fatal accident in subsea tunnels building. The groundwater inrush is high pressure, and the source is infinite. Drain, pumping and heighten the inner air pressure of tunnel are all inefficacious. The basic method of groundwater control is grouting. The paper gives a brief introduction to the leading grouting scheme of tunnels, and studies the water pressure of surrounding rocks'pores after grouting and excavation.2. Leakage of subsea tunnel is outstanding problems in design, construction and service of subsea tunnel. Leakage of subsea tunnel makes the road wet and slip. It can cause the traffic accidents; Leakage of subsea tunnel increases the tunnel humidity and decreases the wind engines and lights working efficiency. The submarine tunnel cannot automatically drain, of which water percolation capacity is related to the design of blocking/draining water schemes during the tunnels'construction and operation. The paper measures the water percolation capacity of the surrounding rocks and held the water percolation distribution rules of the whole tunnel. This paper analyzes the interrelationship between factors like water pressure of surrounding rocks'pores, water percolation capacity of surrounding rocks, waterhead, and grouting and water-blocking effects etc... It provides effective test data for blocking and drainage design and construction of China subsea tunnels, and gives some customized suggestions.3. Various chemicals are in a tunnel's water percolation, for its blocking and drainage systems they have particularly significant influence on reinforced concrete structures, such as Cl-, SO42- ions. The test analyzes the chemical nature of water in different period and places and gain the variation regulation of chemical nature of underground water from subsea tunnels.