研究生知识库

There is a lot of evidence that the internal material of the earth is widely superimposed on the effect of differential stress in addition to the isotropic rock pressure. Differential stress has an important contribution to the free energy of matter, and free energy is the decisive factor in controlling the composition, texture, structure, trait and interaction process of material system. Therefore, the difference stress is the same as the temperature and the isotropic rock pressure, which is one of the most basic thermodynamic variables that control the internal material system of the earth. At the same time, the geological processes of the compaction of the sediments, magmatic differentiation, metamorphic dehydration, atmospheric precipitation, plate subduction and seawater seepage can produce high temperature and high pressure (pore and fracture) water fluid in the crust and even the upper mantle. Thus, there is extensive material and thermodynamic state of the interaction of water-solid (minerals, rocks, ores and solid organic matter) under high temperature, high confining pressure and differential stress in the crust and even upper mantle. On the other hand, the interaction between the solid matter and the high temperature and high pressure water fluid, which is under the high temperature and high pressure, originates from the various physical-chemical processes occurring at the water-solid interface, and these colorful physical and chemical processes. The occurrence and development of the solid sample itself by the free energy constraints. It is clear that the various physical-chemical thermodynamics and kinetic processes that occur at the interface of the fluid-solid interface on the solid sample are subject to additional thermodynamic variables, and the differential stress is necessarily a significant response, on the one hand Solid surface and internal solid phase and chemical composition, texture, structure and various properties of the response to differential stress, on the other hand also reflected in the composition of water, structure and traits of the response to differential stress, thus showing a variety of forms mechanics - chemical coupling. Undoubtedly, the identification of these mechanics - chemical coupling plays a decisive role to the people aware of the earth's internal occurrence of a variety of earth thermodynamics and dynamics of the process, especially in the exploration of the Earth's various diagenetic effects of mineralization.The experimental study of water and solid interaction of shallow crust in high temperature and high pressure is the most important research field. So far, the water-solid interaction experimental platform, which can simulate the depth of the shallow crust, the isotropic rock pressure and the differential stress condition, includes the Paterson press, the Conventional triaxial stress testing machine and the experimental apparatus for differential stress of autoclave. However, all three types of platforms have the following deficiencies: (1) The operating temperature and confining pressure of conventional triaxial stress testing machine and the experimental apparatus for differential stress of autoclave is low; (2) Poor compatibility of functional limitations, such as Paterson press and conventional triaxial stress testing machines; (3) The working mode of all three types of experimental platforms is single. All of these defects have seriously hindered the understanding of the fluid-solid interaction process under the differential stress of the crust. Therefore, it is necessary to develop a more functional high temperature and high pressure test device and in situ measurement technology to reveal the law of material movement within the Earth.This paper successfully developed a water-solid interaction experiment device based on the principles of mechanical, geometrical optics, spectroscopy and automatic control, which can adapt to the high temperature, high confining pressure and differential stress condition of shallow crust.(1) The device has a strong compatibility with white light imaging system, in situ measurement system of Raman spectroscopy, in situ measurement system of three-electrode electrochemical, in situ measurement system of combined chemical sensor and other in situ observation system. This device has all of working modes of three existing types of platforms, including the confining pressure+void pressure+differential stress working model of Paterson press and conventional triaxial stress testing machine, and the working mode of the experimental apparatus for differential stress of autoclave that the water fluid interacting directly with the solid sample subjected to differential stress.(2) The maximum working temperature and confining pressure of the device can reach 650℃ and 100 MPa at the same time. It can carry out various mechanical tests at high temperature and high confining pressure, in which the measurement and control precision of differential stress is 0.1 MPa.(3) The pressure of the small volume of the pressure vessel can be precisely adjusted with the fluid pressure control system of the device, the pressure medium can be a water or gas, or it a mixture of water and gas. The pressure control accuracy of the step-up and step-down process is 0.1 MPa. The confining pressure is independent of the temperature in the case of high temperature and high pressure without changing the composition of the system.(4) The accuracy of measuring the deformation of solid sample reaches 0.5 μm and the resolution is 0.01 μm. With the aid of the high resolution white light imaging system, the in-situ measurement of the axial and radial strain can be achieved more accurately than the existing three types of platforms(5) The heating system of the device, arrangement of heating and cooling system in the wall space within the 15 mm. The outer wall temperature of the heating furnace is lower than 50℃ and the window temperature is lower than 80℃ when the temperature of the inner wall of the heating furnace is 700℃. The temperature control accuracy of the pressure vessel is ±1℃.(6) The reliability of the experimental device and the experimental method was successfully tested by using the titanium alloy (TC11), which is commonly used in the experimental geochemical study. The compression elastic modulus of the TC11 titanium alloy was tested for the first time under high pressure hydrothermal environment. 

大量证据表明，地球内部物质除受到各向同性的静岩压力作用外，在其上还广泛叠加有差异应力的作用。差异应力对物质的自由能具有重要贡献，而自由能是控制物质体系组成、结构、构造、性状及相互作用过程的决定性因素。因此，差异应力与温度和静岩压力一样，其是约束地球内部物质体系最基本的热力学变量之一。与此同时，沉积物的压实成岩过程、岩浆分异、变质脱水、大气降水、板片俯冲以及海水渗流等地质过程在地壳甚至上地幔的岩石空隙（孔隙和裂隙）中均可产生高温高压水流体。因此，在地壳甚至上地幔内部广泛存在高温、高围压和差异应力下的水流体—固体（矿物、岩石、矿石和固体有机质）相互作用的物质基础和热力学状态。而另一方面，地球内部处于高温和高静岩压力下的固体物质与高温高压水流体之间的相互作用起源于水流体—固体界面发生的各种物理—化学过程，而这些丰富多彩的物理化学过程的发生与发展受到固体试件本身自由能的约束。显然，若在固体试件上额外施加差异应力这一热力学变量，水流体—固体界面处发生的各种物理—化学热力学与动力学过程则对差异应力均必然产生显著的响应，一方面表现在固体试件表面和内部的物相和化学组成、结构构造以及各种性质对差异应力的响应，另一方面还表现在水流体的组成、结构和性状对差异应力的响应，从而表现出形式多样的力学-化学耦合作用。无疑，查清这些力学-化学耦合作用对人们认知地球内部发生的各种地球热力学和动力学过程，尤其对探索地球内部发生的各种成岩成矿效应具有举足轻重的作用。地壳浅部的水流体-固体相互作用的高温高压实验研究是地球内部水流体-固体相互作用研究领域最为重要的研究范畴。迄今为止，可模拟地壳浅部深度范围温度、静岩压力和差异应力条件的水流体-固体相互作用实验平台仅包括Paterson压机、常规的三轴应力试验机和高压釜+轴向应力实验装置。但是，该三类平台各自存在如下不足：（1）工作温度、围压较低，例如常规的三轴应力试验机和高压釜+轴向应力实验装置；（2）功能局限兼容性差，例如Paterson压机和常规的三轴应力试验机；（3）工作模式单一，包括所有三类实验平台。所有这些缺陷，严重阻碍了人们对地壳浅部差异应力作用下水流体-固体相互作用过程的认识。因此，研制功能更完善的高温高压试验装置和原位测量技术对揭示地球内部的物质运动规律是十分必要的。本文基于各种机械、力学、几何光学、光谱学和自动控制等原理，成功地研发出了一套能适应地壳浅部高温、高围压和差异应力条件的水流体—固体相互作用实验装置。（1）本装置具有与白光成像系统、拉曼光谱原位测量系统、三电极电化学原位测量系统、组合化学传感器原位测量系统等多种原位观测系统对接的强大兼容性；本装置兼具目前已有三类型平台各自具有的工作模式，包括Paterson压机和常规的三轴应力试验机具备的围压+空隙压+差异应力工作模式，以及高压釜+轴向应力实验装置具备的水流体直接与承受差异应力的固体试件发生相互作用的工作模式。（2）本装置的最高工作温度与围压可同时达到650℃和100 MPa，可以在高温高围压下进行各种力学的测试，其中差应力测量和控制精度为0.1 MPa。（3）利用本装置的流体压力控制系统，可以对小容积的压力容器的压力进行精确调节，传压介质可以是单一水流体或气体，也可以是水流体和气体的混合物；升压和降压过程的压力控制精度均为0.1 MPa；在高温高压和不改变体系物质组成的情况下，实现围压独立于温度进行调节。（4）本装置测量固体样品变形的精度达到0.5 μm，分辨率达到0.01 μm；本装置借助高分辨率的白光成像系统可实现比目前已有三类型平台更加精准的轴向和径向应变原位测量。（5）本装置的加热系统，在15 mm的壁厚空间内布置加热元件和冷却系统，做到加热炉内壁温度在700℃的情况下，加热炉外壁温度低于50℃，窗口温度低于80℃，且压力容器内部温度控制精度为± 1℃。（6）以实验地球化学研究常用的高压釜材料钛合金（TC11）为样品，成功检验了实验装置和实验方法的可靠性，并利用本装置首次在高压水热环境下对TC11钛合金的压缩弹性模量进行了测试。