某水电站厂房下卧软弱夹层基础岩体质量及灌浆效果评价

Rockmass Quality and Grouting Effect Evaluation of Underlain Soft Interlayer in Some Water Power Station

某水电站厂房基础在帷幕灌浆时出现钻孔涌水并伴有黄色泥浆、浆液大量流失现象。通过深挖厂房基础集水井初步探明,下卧1 m多厚性状较差软弱夹层,从而迫使施工停止。为了快速查明软弱夹层的分布范围、性状特征及对基础稳定性影响,在厂房区利用12个灌浆钻孔进行声波测试,并取岩芯进行单轴抗压强度和波速测试,评价了基础质量,揭示了软弱夹层的厚度及其分布。通过Ⅰ序灌浆和Ⅱ序灌浆前后的波速对比测试,评价了基础的灌浆效果,为基础质量验收提供了重要依据。

A blow with yellow slurry appeared in the borehole of some hydropower station foundation when currain grouting was conducting, and grout run out largely. According to the data of the deep collecting well in the workshop foundation, it was found that a weak interlayer with thickness of more than one meter exists in the underlain layer. So the construction was stopped. To find the effect on the foundation stability caused by distribution range and properties, twelve grouting boreholes were used to do the ultrasonic testing. Rock core was used for the single axis compression strength and ultrasonic wave velocity testing, then foundation quality was estimated and weak interlayer thickness and their distribution was revealed. The grouting effect is estimated by comparing ultrasonic wave velocity in grouting order Ⅰ with that of grouting order Ⅱ, finally, it provides important basis for foundation quality check and acceptance.