Response of saturated soil to the intense heat of tunnel fires

建筑物对火灾影响的敏感性是众所周知的，在9/11世贸中心倒塌事件中令人震惊地证明了这一点。地下建筑发生火灾的情况并不少见，而且似乎在增加频率和严重性。在长期的隧道火灾中，邻近土壤的温度可能上升高达400摄氏度或更高。土壤中的这些高温和相关的温度梯度预计将影响整个地下结构的稳定性。这项研究的具体目标是研究饱和土壤对与严重隧道火灾相关的温度梯度的响应。这项探索性的实验研究将研究饱和土壤在公共通道铁路和公路隧道火灾的长期高温特征下的系统响应。它得到了探索性研究小额赠款计划的支持。将建立一个物理模型，代表一个简单的一维圆柱形核心，由隧道衬砌的一段及其上方的饱和土壤组成。该模型将受到隧道火灾中预期的火灾荷载。它将被测量，并测量土壤的力学性质的变化。这一简单的方法将初步了解温度分布、水的热诱导运动、孔隙流体的蒸发、固结和其他孔隙流体行为引起的土壤运动，以及响应典型的原位热、流体压力和超载条件的土壤性质的变化。从技术角度来看，这项基础研究最终将通过改进可能遭受强烈和长期火灾的地下土木工程结构的原始设计和补救设计来促进公共安全。此外，它还将在不同的工程学科之间产生科学讨论：岩土工程和消防工程。

The sensitivity of structures to the effect of fire is well established and was stunningly demonstrated in the World Trade Center collapse of 9/11. Fires in underground structures are not uncommon, and appear to be increasing in frequency and severity. In prolonged tunnel fires, the temperature of the adjacent soil can rise as much as 400C or more. These high temperatures and associated temperature gradients in the soil are expected to impact the stability of the entire underground structure. The specific objective of this research program is to examine the response of saturated soil to temperature gradients associated with severe tunnel fires.This exploratory experimental research will address the system response of saturated soil subjected to prolonged, intense temperatures characteristic of public access rail and highway tunnel fires. It is supported under the Small Grants for Exploratory Research program. A physical model will be constructed that represents a simple one-dimensional cylindrical core from a section of the tunnel lining and the saturated soil above it. This model will be subjected to the fire loads expected in tunnel fires. It will be instrumented, and changes in the mechanical properties of the soil measured. This simple approach will provide a preliminary view of the temperature distribution, the thermally induced movement of water, vaporization of pore fluid, soil movement due to consolidation and to other pore fluid behavior, and changes in soil properties in response to representative insitu heat, fluid pressure, and surcharge conditions. More sophisticated model investigations to be initiated subsequent to this study will be based on these preliminary experimental results.From a technical point of view, this basic research ultimately will contribute to public safety through improved original design and remedial design of underground civil engineering structures that may be subject to intense and prolonged fire. In addition, it will generate a scientific discussion between distinct engineering disciplines: Geotechnical Engineering and Fire Protection Engineering.