Quality control for seepage prevention wall construction by water jet and trench - cutting method

Based on the construction practice of the vertical impervious core in the No. 1 and No. 2 bidding sections of the important Tongma dyke strengthening works of the Yangtze River, the construction technology and characteristics of the water jet method and the trench - cutting method are expounded. The construction technology of impervious cores by water jet method is simple and well suitable for various strata. After the construction equipment for this method is improved, it can penetrate cobble strata, rock blocks, etc., and construct impervious cores with their depth up to 28.5 m. The inclination control of trenches is the key and difficult point in quality control for the water jet method, because an accurate verticality of trenches is required. The construction technology of impervious cores by the trench - cutting method is relatively complicated and only suitable for a limited sort of strata, but the impervious core can be successively constructed and its quality is easy to guarantee. For the trench - cutting method, the focal point of quality control is in the body isolated by geotechnical cloth sacks and the placement of concrete in trenches. The inspection of completed impervious cores through excavating exploratory pits and core extraction shows that the quality of the impervious core body and its joints meets the design requirements.