Fundamental investigation of compensation grouting using transparent soil

这项拟议的研究将实验研究补偿灌浆，通过实时可视化的传输灌浆和水力压裂，使用透明的土壤。研究成果对补偿灌浆的设计和施工具有直接的指导意义。 补偿灌浆是一项较新的技术，它是在高压下注入低粘度浆液，以补偿由于邻近地下建筑物引起的地面损失。它已成功应用于许多城市地区，特别是在隧道施工中。然而，补偿灌浆的机理还没有得到很好的理解，因为它涉及到一组复杂的参数，由于不同的土壤条件以及灌浆变量。灌浆在土壤中的注入涉及土壤骨架、流体流动和灌浆运输之间的复杂相互作用。一般认为，补偿灌浆包括压密灌浆和劈裂灌浆两种灌浆方式。补偿灌浆的应用在很大程度上依赖于实践经验和经验性。开发高效经济的灌浆方案需要深入了解灌浆机理及其控制参数。已经进行了一些实验室研究，对灌浆有了基本的了解。然而，有有限的研究初始化和几何形状的裂缝，灌浆在土壤中的传输。在注入过程中也没有进行土壤位移测量。 这项拟议的研究将使用透明土壤来解决这些问题，并提供一个完整的了解灌浆运输和土体内的压裂。为了实现这些目标，将开发一种最先进的光学测量系统，以便能够对灌浆参数进行实时数据采集和图像捕获。光学系统由一个激光器和两个配置良好的摄像机组成，激光器用于照亮透明土壤内的目标横截面，摄像机用于同时捕获被照亮部分的图像。三维土壤变形将使用立体粒子图像速度技术计算。灌浆过程中土壤变形的信息将有助于解决补偿灌浆中有效控制沉降的灌浆效率问题。数字图像边缘检测将用于描绘灌浆体的几何形状，识别裂缝的初始化，并观察裂缝的方向和几何形状。本研究将进行一系列缩比模型试验，主要是在实验室1-g条件下进行。将检查控制参数的影响，包括土壤条件、上覆压力、灌浆成分、注入速率和注入压力。将进行一些离心模型试验，以补充1-g模型试验，从而更好地模拟现场的应力梯度条件。还将进行数值模拟，以系统地研究各种影响因素的影响。 这项拟议的研究将是第一个可视化的浆液在多孔介质中的传播和初始化的水力裂缝灌浆过程中在真实的时间。该研究计划对改变或改进民用，环境和石油工程领域的许多现有技术具有重要意义。拟议的研究也是至关重要的培训HPQ为他们的职业发展在加拿大。

This proposed research will experimentally investigate compensation grouting through the real-time visualization of the transport of grout and hydraulic fracturing by using transparent soil. The findings from this research program are expected to directly benefit design and construction of compensation grouting in practice. Compensation grouting is a relatively new technique which injects a low viscosity grout at high pressure to compensate for ground loss due to adjacent underground construction. It has been successfully applied in many urban areas, particularly during tunnelling. However, the mechanisms of compensation grouting are not well understood as it involves a set of complex parameters due to different soil conditions as well as grouting variables. The injection of grout inside soil involves complex interactions between the soil skeleton, fluid flow, and grout transport. It is generally understood that compensation grouting consists of two grouting modes: compaction grouting and fracture grouting. The application of compensation grouting heavily relies on practical experience and empiricism. The development of an efficient and economical grouting program requires a thorough understanding of the grouting mechanisms and its controlling parameters. A few laboratory studies have been conducted that have obtained a basic understanding of grouting. However, there is limited research on the initialization and geometry of fractures, and the grout transport in soils. There are also no soil displacement measurements made during injection. This proposed research will use transparent soil to address these issues and provide a full understanding of grout transport and fracturing inside a soil mass. In order to achieve these goals, a state-of-the-art optical measurement system will be developed to be able to conduct real-time data acquisition of the grouting parameters and image capture. The optical system consists of a laser to illuminate a targeted cross section inside the transparent soil and two well-configured cameras to simultaneously capture the images of the illuminated section. Three-dimensional soil deformation will be calculated by using a stereo particle image velocity technique. The information on soil deformation during grout injection will help to address the issue of grout efficiency in compensation grouting for efficient settlement control. Digital image edge detection will be used to delineate the geometry of the grout body, identify the initialization of fractures, and observe the direction and geometries of fractures. A series of scaled model tests will be carried out in this study, mainly under 1-g conditions in the laboratory. The influence of the controlling parameters will be examined, including soil conditions, overburden pressure, grout composition, injection rate, and injection pressure. A few centrifugal modeling tests will be conducted to complement the 1-g model tests to better simulate stress gradient conditions in the field. Numerical simulation will also be conducted to provide a systematic investigation of the influence of various influencing factors. This proposed research will be the first of its kind to visualize the propagation of grout in a porous medium and the initialization of hydraulic fractures during grout injection in real time. This research program has significant implications of changing or improving many existing technologies used in civil, environmental, and petroleum engineering fields. The proposed research is also vital in training HPQs for their career development in Canada.