地震由斷層滑動並釋放應力所引發，斷層快速滑動時的岩石變形機制受到高溫驅動之物理或化學作用與孔隙水壓所影響。其中，由於孔隙水壓難以量測，過去對地震時孔隙水壓的估計主要有兩種方式：1.設定各種岩石物理的參數，代入耦合方程式，估計滑動時的孔隙水壓變化; 2.進行岩石力學實驗並量測孔隙水壓。本實驗室特製的斷層泥樣品容器，可以於飽和水狀態對斷層泥施加快速滑動的條件，並施加高的正向應力(高達18 MPa)。Nguyen et al. (under review)對飽和水高嶺土進行高速旋剪摩擦試驗，獲得摩擦行為、溫度變化、微觀構造與礦物相變等資訊。本研究目的為建立一熱水力化耦合模擬，提供未來實驗室旋剪實驗之孔隙水壓估計的工具。因此，本研究以阮氏貞之實驗數據，進行耦合，並以量測到的溫度做為制約，對模擬之溫度進行修正，進而獲得可能之孔隙水壓變化。最後模擬結果顯示，滑動帶的溫度不斷增加，孔隙水壓也持續地累積上升。由於孔隙水壓的增加可能降低有效應力，將此模擬結果與摩擦行為連結，暗示造成斷層泥的弱化現象，可能為高溫導致的高液壓所造成，也就是熱增壓作用。本研究的模擬結果，需基於實驗數據(包含力學與溫度)以及樣本的微觀構造分析，才可能獲得可信之熱水力化結果。;Earthquakes are triggered by fault slip and release stress. The deformation mechanism of rocks during rapid fault slip is influenced by thermally driven physical or chemical processes and the associated pore fluid pressure. Estimating pore fluid pressure during earthquakes has been challenging due to its difficulty in measurement. In the past, there have been two main approaches to estimate pore fluid pressure during seismic events: 1. Setting various physical parameters of rocks and incorporating them into coupled equations to estimate pore fluid pressure changes during sliding; 2. Conducts rock friction experiments and measures pore fluid pressure. Recently, our laboratory has developed a sample holder for fault gouge samples, which can apply rapid sliding conditions to fault gouge under water-saturated conditions and high normal stresses (up to 18 MPa). Nguyen et al. (under review) has performed high-velocity rotary shear friction tests on saturated kaolinite to obtain information on friction behavior, temperature changes, microstructures, and mineral phase transformations. The aim of this study is to establish a thermo-hydro-mechanical-chemical coupling simulation tool to estimate pore fluid pressure in future laboratory rotary shear experiments. Therefore, based on Nguyen et al. (under review) experimental data, the simulation is performed, and the simulated temperature is adjusted using the measured temperature as a constraint to obtain possible variations in pore fluid pressure. The simulation results show that the temperature within the principal slip zone keeps increasing, and the pore fluid pressure continues to accumulate. The increase in pore fluid pressure may reduce the effective stress, and when linked to the friction behavior, it implies a fault weakening mechanism in kaolinite samples possibly caused by high temperatures-induced fluid pressures, known as thermal pressurization. The simulation results of this study rely on experimental data (including mechanical data and temperature) and microstructural analysis of the samples to obtain reliable thermo-hydro-mechanical-chemical results.
