西霞院电站厂房基础混凝土灌注桩施工

西霞院电站厂房基础局部承载力不足,设置了后压浆混凝土灌注桩加固地基。施工中遇到了塌孔、串浆、冒浆、地基抬动等难题,采取了黏土、水泥、碎石回填,管井、减压井、挖深坑降水,变化浆液浓度和压力进行间歇灌浆,设置抬动观测点等措施,解决了难题,并通过高密度电法,频谱激发极化法,地震波测试,低应变、高应变和静载试验等方法,对扰动区充填加固效果及桩基质量进行了检测。结果表明,地层充填加固效果良好,桩基施工质量满足设计要求。

Cast-in-place concrete pile construction in powerhouse foundation treatment of Xixiayuan Project

In consideration of the insufficient local bearing capacity of powerhouse founaaUon ot Xixiayuan Project, me postgrouted concrete pile was adopted for reinforcement of the foundation. Some measures, such as backfilling with clay, cement, and crushed stones, water-level reduction by pipe wells, rehef wells, and digging deep pits, intermittent grouting by change of the density and pressure of grout, and setting of the measurement points for lifting observation, were adopted to overcome the difficulties occurring in the construction period, including hole collapse, grout leakage and overflow, foundation lifting, and so on. Moreover the high-density electricity method, the frequency-spectrum excitation and polarization method, the earthquake wave test method, and the high-strain, low-strain, and static load tests were adopted for checking the grouting consolidation effect in disturbed zone and quality of pile foundation. The result shows that the stratum backfill and consolidation effect is satisfactory, and the construction quality of pile foandation meets the requirement of the design.