Assessing the roles of wear and roughness on dynamic fault friction

评估磨损和粗糙度对动态故障摩擦的作用

• 批准号: 2338973
• 负责人: Monica Barbery
• 金额: $ 41.48万
• 依托单位: Brown University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2024
• 资助国家: 美国
• 起止时间: 2024-06-01 至 2027-05-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2338973&HistoricalAwards=false
• 关键词: Assessing; roles; wear; roughness; dynamic

Faults that host earthquakes are naturally rough. Rough patches on fault surfaces can collide and lock, preventing any further movement on a fault. Earthquakes begin when these rough patches break, and earthquake characteristics are controlled by frictional processes at the fault surface that evolve as the earthquake occurs. This project will advance our understanding of the physics of earthquakes by exploring two mechanisms that may regulate the friction of faults during earthquakes. The first occurs when heating leads to increased pressure in fluids, which can promote continued slip in earthquakes through lubrication, and the second is hardening due to producing more space for the lubricating fluids, which can impede earthquakes. To better understand these processes, the PI will conduct experiments at earthquake like conditions using a one-of-a-kind deformation apparatus at Brown University. The PI will test the roles of natural fault roughness and wear processes on the two competing processes. The results from this work will advance our understanding of earthquake physics and will inform the development and modification of new and existing earthquake rupture models. These models play a vital role in mitigating earthquake hazard and risk worldwide by improving the understanding of earthquake processes. This project will also enable the PI’s continued participation in DEEPS CORES, a program that develops and implements STEM curriculum for local Providence public schools. DEEPS CORES aims to expand participation in STEM fields from under-represented groups and to improve science literacy of the general public.Experimental validation of physics-based constitutive equations that describe the frictional behavior of geologic materials during seismic slip is a critical step in advancing physics-based dynamic rupture models for earthquakes. This work will use the newly modified Tullis Rotary Shear Apparatus at Brown University to conduct several suites of dynamic rock friction experiments investigating two mechanisms that may regulate the frictional behavior of faults during earthquakes: thermal pore-fluid pressurization weakening (TPW) and dilatancy hardening (DH). TPW occurs as frictionally heated pore fluids thermally expand faster than the fault pores. In poorly drained conditions during seismic slip, this leads to increases in the pore pressure that decrease the shear stress acting on the fault thereby weakening the fault. DH has the opposite effect in which shearing causes the formation of new microcracks increases total pore volume, thereby reducing pore fluid pressure and strengthening faults. TPW will only be significant during earthquakes if DH is minimal. To elucidate to roles of wear and fault roughness on dynamic friction and explore the balance between TPW and DH, the PI is conducting experiments at slip rates up to 1 m/s, elevated confining pressures (45-60 MPa), and elevated pore pressures (25-40 MPa) on samples with both variable permeability and sliding surface roughness mimicking the range of fault roughness measured on faults in nature. Mechanical data will be combined with microstructural analysis and micromechanical modelling to guide the analysis and interpretation of results. These experiments will be the first with independently controlled and elevated pore pressure, confining pressure, and normal stress at slip rates of 1 m/s. It will establish conditions under which wear processes, enhanced by natural fault roughness, allow TPW to develop in samples with varying permeabilities and will also establish the extent to which DH counteracts TPW on rough surfaces at high displacements.This project is jointly funded by the Division of Earth Sciences, Geophysics Program and the Established Program to Stimulate Competitive Research (EPSCoR).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

当骨质量在地质量上发生时，当液体的压力增加时，骨会破裂，而第二个则因润滑液而硬化，并且第二次会损害地震将在布朗大学使用A型变形设备进行地震的实验。通过改善对地震过程的理解，在全球范围内的重要作用，PI继续参与Deeps Core，该计划发展并实现了STEM CURICULUM FORIRAM FORIRAL SURICULUM forrical公立学校。公众的素养。实验的utive方程式，地质物质的the词是促进地震的物理模型的关键一步。离子弱（TPW）和膨胀性硬化（DH）在吊索地震地震中的池状条件下，这会导致压力上的压力增加，从而削弱了DH的效果。微裂纹会增加涡流体积E和强度的断层。在自然分析和微机械分析中测量的fort粗糙度的可变渗透性和表面粗糙度的样品（25-40 MPA）模仿了孔的分析和解释。提出和处于1 m/s的滑动速率的正常应力，使TPW在具有不同渗透率的样品中发展，并且还确定了DH DH DH DH DH在高位移处的粗糙表面上的TPW。 E Earth Science，E建立的刺激研究计划（EPSCOR）。该奖项反映了NSF'SFFLY的使命，并使用基金会的知识分子优点和更广泛的影响评估标准通过评估来实现了值得的评估。