Development of undisturbed sampling method using thick water-soluble polymer

发明了一种使用稠的水溶性聚合物的新的取样方法，以从甚至困难的地面获得原状样品。本研究的目的是了解这种方法的特点，以评估聚合物浸泡效果，使这种方法的深地面和应用这种方法的井下三轴试验。通过岩心筒旋转实验，测量了岩心表面的正应力和剪应力。结果表明，由于厚聚合物的Wisenberg效应，剪切应力最小，而法向应力为几千帕斯卡。通过室内渗透试验研究了聚合物在砂土中的渗透特性。2）对含聚合物砂土试件进行了一系列三轴压缩试验。试验结果表明，内摩擦角几乎不受影响，而粘聚力值的增加有限，不超过几千帕斯卡。3）研制了用于该聚合物深地层取样的岩心筒，并尝试从疏松砂层中获得原状样品。从10至22米深的地下获得了直径为100毫米的连续岩心，显然没有受到干扰的迹象。此外，还成功研制了直径为200 mm的大直径岩心筒，用于从大砾石或大块贝壳等不均匀地层中采集聚合物样品。4）开发了利用该聚合物取样方法制备井下三轴试验试件的技术。在砂浆地面上的试验表明，圆柱形试样可以通过这种技术在地面上精确钻孔。

A new sampling method using thick water-soluble polymer was invented to obtain undisturbed samples from even difficult ground. The objectives of this study were to understand the characteristics of this method, to evaluate the polymer immersion effect, to allow this method for deep ground and to apply this method for down-hole triaxial test. The following conclusions were drawn.1)Measurement of normal and shear stresses on the drill-core surface was made by the core barrel rotation experiments. The results revealed that, the shear stress was minimal while normal stress of several kilo Pascal's was recorded due to Wisenberg effect of the thick polymer. In addition, seepage tests were conducted to elucidate seepage characteristics of polymer into sand.2)A series triaxial compression tests were conducted on sand specimen with polymer. The test results demonstrated that, there was practically no influence on the angle of internal friction whereas increase of the cohesion value was limited as no more than several kilo Pascal's.3)A core barrel was developed for this polymer sampling from deep ground, and an attempt was made to obtain undisturbed samples from unconsolidated sand layers. Continuous drill cores of 100 millimeter diameter apparently with no sign of disturbance were obtained from 10 to 22 meters deep ground. Moreover, a larger diameter core barrel of 200 millimeter diameter was also successfully developed for the polymer sampling from non-uniform ground including large gravels or large pieces of sea shells.4)A technique to prepare the test specimens for down-hole triaxial tests was developed utilizing this polymer sampling method. Trial attempts on mortar ground demonstrated that cylindrical specimens can be accurately drilled in the ground by this technique.