New loading system and measurement equipment for an existing testing pit

岩土工程领域问题的多样性和复杂性日益增加，要求经济和可持续地使用地质材料（土壤和岩石）和类土材料（例如矿物材料，RC材料，工业副产品，工业和焚烧厂的废物），需要更深入地了解它们的力学行为，如实验所观察到的。尽管在过去的几十年里，科学的努力，模型的开发和验证，以模拟复杂的耦合流体力学响应的多相岩土材料仍然属于最具挑战性的研究领域，在岩土工程。为了实现研究提案的目标，必须扩大慕尼黑技术大学Zentrum Geotechnik的实验能力，全面检查循环、交替和动态载荷下土壤和类土壤材料的耦合水力力学行为。所需设备的重点主要在于研究在受控或监测边界条件下剪切载荷期间的行为。使用新设备进行的实验必须涵盖剪切应变幅度、应力路径、压力和排水条件的大范围，这些与所考虑的不同岩土问题相关。到目前为止，慕尼黑工业大学和巴伐利亚大学的测试设备还不能满足所有这些要求。因此，本申请中描述的测试设施对巴伐利亚州未来的研究具有战略重要性。这项拨款申请旨在为一个新的装载系统以及用于测试大型模型的测量设备提供部分资金，这些模型可以安装在现有的测试坑中。在8米深的测试坑内，可以在高达1.500 kN的循环和动态载荷下检查岩土边界值问题。测试设备的其他组件是共振柱装置（简称：RC装置）、循环动态三轴测试装置（简称：DTX装置）和全向简单剪切装置（简称：ODSS装置）。在ODSS装置中，通过控制剪切变形的两个运动学独立方向上的剪切应变或剪切应力来施加循环、交替和动态载荷。ODSS装置以及DTX装置允许在中等至大剪切应变振幅范围内进行研究。与ODSS装置相反，DTX装置控制主方向上的应力和应变，而样品中主方向的旋转是使用ODSS装置的特征之一。在RC装置中，可以通过使圆柱形样品进入共振来确定小剪切应变幅范围内的刚度和滞后阻尼。

The increasing diversity and complexity of problems in the field of geotechnical engineering and the claim for an economical and sustainable use of geomaterials (soil and rock) and soil-like materials (e.g. mineral materials, RC-materials, industrial by-products, waste from industry and incineration plants) require a much deeper understanding of their mechanical behaviour, as observed experimentally. Despite of the scientific effort in the last decades, the development and validation of models to simulate the complex coupled hydro-mechanical response of multiphase geomaterials still belongs to the most challenging fields of research in geotechnical engineering. In order to achieve the goals of research proposals, an extension of the experimental capabilities of the Zentrum Geotechnik of the Technical University of Munich for the comprehensive examination of the coupled hydro-mechanical behaviour of soil and soil-like materials under cyclic, alternating and dynamic loadings is imperative. The focus of the required equipment lies primarily on the investigation of the behaviour during shear loadings at either controlled or monitored boundary conditions. The experiments to be carried out with the new equipment have to cover the large range of shear strain amplitudes, stress paths, pressures and drainage conditions, which are relevant for the different geotechnical problems under consideration. So far, the testing equipment available at the Technical University of Munich and at universities in Bavaria does not satisfy all these requirements. Therefore, the testing facility described in this application is of strategic importance for the future research in Bavaria. This grant application aims for the partial funding of a new loading system as well as measurement equipment for testing large-scale models that can be set up in an existing testing pit. Within the 8 m deep testing pit geotechnical boundary value problems can be examined under cyclic and dynamic loadings up to 1.500 kN. Further components of the testing facility are a Resonant Column Device (in short: RC-device), a Cyclic Dynamic Triaxial Testing Device (in short: DTX-device) and an Omnidirectional Simple Shear Device (in short: ODSS-device). In the ODSS-device, the cyclic, alternating and dynamic loadings is be applied by controlling either the shear strain or the shear stress in two kinematically independent directions of shear deformation. The ODSS-device as well as the DTX-device allows the investigation in the range of medium to large shear strain amplitude. In contrary to the ODSS-device the DTX-device controls stress and strain in the principal directions while the rotation of the principal directions in the sample is one of the features using the ODSS-device. In the RC-device, the stiffness and hysteretic damping in the range of small shear strain amplitude can be determined by bringing a cylindrical sample into resonance.