Characterization of a Sedimentary Soft Rock by a Small In-Situ Triaxial Test
Characterization of a Sedimentary Soft Rock by a Small In-Situ Triaxial Test
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DOI：
10.1007/s10706-008-9245-9
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发表时间：
2010-05
影响因子：
1.7
通讯作者：
A. Taheri;K. Tani
中科院分区：
文献类型：
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作者：
A. Taheri;K. Tani
为了测量沉积软岩的抗剪强度和变形能力，提出了一种小型井下原位三轴试验方法。该装置包括一个三轴单元和一个轴向加载装置，可以在任何深度进行测试。在该方法中，可以在钻孔底部剪切直径为90 mm，高度为285 mm的柱状试样。在一个50米深的实验洞穴中进行了一系列的试验。试验巷道位于泥岩中，有层间薄砂层。试验采用多级加载法，在井眼的三个不同深度进行。新的测试方法成功地测量了岩体的应力-应变关系。试验结果表明，在泥岩地层中，如果选择合适的载荷反转准则，通过加载过程中的应力-应变关系识别破坏瞬间，多级加载方法是可以接受的。此外，含砂层泥岩岩体的力学性质也有不同的结果。同样的加载方法在试件中部存在砂层的情况下也不适用，因为在加载初期会造成较大的损伤。
To measure the shear strength and deformability of a sedimentary soft rock, a small down-hole in-situ triaxial testing method is developed. The apparatus consists of a triaxial cell and an axial loading device which enables testing at any depth. In this method, a columnar specimen of diameter 90 mm and 285 mm height can be sheared at the bottom of a drill hole. A series of tests were conducted at a 50 m deep experimental cavern. The test gallery is contained in mudstone with some inter-bedded thin sand layers. The tests were done in three different depths in a borehole by a multiple-step loading method. The new testing method was successful to measure stress–strain relation of rock mass. The test results demonstrated that the multiple-step loading method is acceptable in mudstone formation, if an appropriate criterion for load reversal is selected to recognize the instant of failure by stress–strain relation during loading. In addition, different results for mechanical properties of mudstone rock mass were observed in the specimens contained sand layers. It is also concluded that, the same loading method is not successful if a sand layer is located in the middle of the specimen due to large damage induced in early stages of loading.