Engineering Research Equipment Grant: Development of a Plane Strain Apparatus for Soft Rock and Concrete

这项工作的目的是开发一种平面应变仪，用于“软”(无侧限抗压强度低于35兆帕)岩石和混凝土，基于刚性框架设计。该装置的独特之处在于，不会对形成故障面施加运动学约束。通过将上压板放置在直线轴承上，试件可以自由地形成由两个被局部变形区隔开的刚体组成的失效机构。应力在整个加载历史过程中是静态确定的，即使在大位移时也是如此。失效过程通过声发射的位置进行映射。解决了摩擦约束问题，提出了一种测量方案。采用平面应变仪的研究项目包括分叉现象的验证和本构模型材料参数的确定。

The objective of this work is to develop a plane strain apparatus for "soft" (unconfined compressive strengths below 35 MPa) rock and concrete, based upon a stiff-frame design. The unique feature of the device is that no kinematical constraints are imposed on the formation of a failure plane. By placing the upper platen on a linear bearing, the specimen has the freedom to form a failure mechanism consisting of two rigid bodies separated by a localized zone of deformation. The stresses are statically determinate throughout the load history, even at large displacements. The failure process is mapped by the locations of acoustic emissions. The problem of frictional constraint is addressed and an instrumentation plan is suggested. The research projects for which the plane strain apparatus will be used, involve the verification of bifurcation phenomena and the determination of material parameters for constitutive models.