In Situ tests to Determine the Ground Pressure Existing in a Soft Rock Mass by Use of Hydraulic Borehole Cells.

本文采用美国矿务局lu博士研制的水力钻孔机测量软岩体地压系统进行了现场试验。该系统由一套液压井眼压力单元、液压压力表、液压泵组成。井眼压力元件由一个圆柱形压力元件（CPC）和两个扁平压力元件（BPC）组成。这个项目延期了两年。第一年，测量了这些压力电池的物理和机械性能，并根据这些测量结果重新排列了这些性能。第二年，在两个岩体场地进行了地压的原位测量，一个是在地下矿坑的岩柱上（火山凝灰岩，覆岩= 120m），另一个是在煤矿的地下进路工作面（壳层，覆岩= 600m）。这些场地的实测地压与理论计算值基本相等。但是，由于岩体中存在或大或小的裂缝，导致钻孔内壁不光滑，给钻孔插入压力元件的工作带来了麻烦。

In situ tests are conducted for adopting the measuring system of ground pressure existing in a soft rock mass by use of hydraulic borehole cells, which had been developed by Dr.P.H.Lu in U.S.Bureau of Mines.This system is consisted from a set of hydraulic borehole pressure cells and hydraulic pressure gauge, hydraulic pressure pomp. And the borehole pressure cells are consisted from a cylindrical pressure cell (CPC) and two flat type pressure cells (BPC).This projects were held by two years. At the first year, physical and mechanical properties of these pressure cells were measured and the properties were re-arranged by these measurements. And at the second year, in situ measurement of ground pressure were conducted by two rock mass sites, the one was on an rock pillar in underground pit (volcanic tuff, covered rock = 120m), and the other was underground drift face of a coal mine (shell, covered rock = 600m).The measured ground pressures of these sites were nearly equal to calculated value of theoretically. But, there were some troubles on a working of inserting the pressure cells in the drilled borehole, when inner wall of the boreholes were not smooth by the large or small cracks in the rock mass.