Abstract：
In light of the problems that exists regarding back water stops for the construction joints of tunnel linings, the following inprovements were tested: (1) the water stop section was designed as trapezoid, which allows two wings to go deeply into the lining concrete and allows both sides of the flange to have enough space to fill the concrete; (2) the drainage holes were set at the side towards the water, with the geotextile on the top and the lower part to connect with the tunnel drainage system; (3) with the artificial crown, the back water stop to became the middle-buried one at the top; and (4) with buried pipes in the base of the lining, the two ends of the water stop were inserted into the groove and connected with a drain pipe without any middle joints.
2012, Vol. 49 