高压压水试验在深钻孔中的应用

Application of high water-pressure test to deep borehole

常规压水试验一般按三级压力、五个阶段进行。三级压力一般分别为0.3,0.6,1MPa。但对于水库大坝、深埋地下工程等水头很高的工程而言,常规压水试验结果不能反映实际水头压力作用下岩体的渗透特性。试验在某花岗岩地区500m深孔中进行,因此选定压力阶段为2,4,6MPa。试验段长度取为6.5m,钻孔中共取21个典型区段进行高压压水试验,试验结果表明,高压压水试验能很好地反映岩体透水性的变化规律。该地区属低渗透岩体,因此在该地下工程灌浆处理裂隙岩体时最小灌浆压力值应不小于5MPa。

Generally, conventional water-pressure test is always carried out with five phases and three pressure stages, 0.3, 6 MPa and 1 MPa. But for some Engineerings with high water pressure such as the dam and deep covered underground ones, the results of the conventional water-pressure test can＇t reflect the true permeability characteristic of the rock mass. The experiment is carried out in a 500m borehole of a granite region, and the pressure stages are designed as 2, 4 MPa and 6 MPa. 21 typical segments are selected to carry out high water-pressure test and the length of each segment is 6.5 m.The seepage law of this area is obtained through high water-pressure test. The permeability is relatively low. The grouting pressure should be larger than 5MPa when treat with fracture rockrnass.