土坝劈裂灌浆技术在甘肃省靖远电厂灰场坝的应用

Fracturing grouting to strengthen a coal ash storing dam of Jingyuan thermal power plant

贮灰坝的坝体土料为湿陷性黄土,70％～80％均为粉土,由于施工质量较差,干容重的合格率仅为41.4％,为此需用劈裂灌浆加固。灌浆孔呈梅花形布置,坝顶布11排孔,排孔距5×3m,用粘粒含量15％～25％的土料制浆,其容重1.3～1.5t/m^3。灌浆孔口压力一般为0.4Mpa,间歇复灌不少于6次,相邻孔或几排孔同时灌注,单孔最大吃浆量为62m^3。灌后的坝体稳定安全系数为1.8,渗透系数较灌前降低了10倍,满足了设计要求。目前水库已蓄灰10～15m(坝高20m),坝后无渗水洇湿现象。

The dam is built of the loess soft with 70%～80% of silt. The construction quality was poor, only 41.4% of the dam body compacted up the design standard. So a fracturing grouting was adopted to strengthen the clam. Along the dam crest drills were Located in distance of 5m×3m in 11 rows. A slush slurry with clay content of 15%～25% and unit weight of 1.3～1.5t/m^3 was injected under a pressure of 0.4 MPa simultaneously into a number of drills closely located. The grouting repeated at least 6 times with intervals. The maximum slury consumption was 62m^3. Due to the grouting, the safety coefficient of dam stability has increased up to 1.8 and the seepage loss has reduced by 10 times, all up the design standards. Now the ash has stored as thick as 10～15m (the dam's height is 20m) and no seepage observed on dry darn slope.