钻孔应变三维测量系统研究

The deformation of the deep crust will produce distortions, folds and other non-horizontal deformation under the action of stretching and extrusion, due to the complexity of geological structure and the diversity of force source. Even in the near earth surface, the tectonic movement can cause the crust to produce non-horizontal deformation, such as uplift and subsidence, and the deformation of the seismic belt and tectonic zone is inhomogeneous. Horizontal four component borehole strain- meter is one of the main observation equipment of crustal deformation. Only horizontal strain observation at present, it is impossible to observe the three-dimensional inhomogeneous deformation characteristics of the crustal medium.. In this project, we will develop the three-dimensional observation sensing technology of borehole strain, through the breakthrough of the technical bottleneck that the current borehole strain is confined to the horizontal observation. Through differential capacitance micro-displacement sensing technology and special mechanical measurement structure design, develop inclined and vertical line strain measurement unit, and integrate on the basis of the existing horizontal four-component borehole strain-meter technology, implement line strain measurement of horizontal 4 components, inclined 2 components and vertical component. Through build a borehole additional strain solution physical model, observe the non-uniform deformation before earthquake and co-seismic, improve the application of borehole strain strain-meter observations in earthquake prediction and earth science research.

由于地质构造的复杂性与力源作用的多样性，深部地壳在拉伸挤压作用下，会产生扭曲、褶皱等非水平向的变形，即便在近地表，构造活动也会使地壳产生隆升、沉降等非水平形变，地震带、构造带的变形表现为非均匀特征。水平四分量钻孔应变仪作为地壳形变的主要观测手段之一，目前以地表水平向观测为主，无法全面对地壳介质三维非均匀性变形特征进行观测。.本项目拟开展钻孔应变三维观测传感技术研究，突破目前钻孔应变仅限于水平观测的技术瓶颈，通过差动电容微位移测量传感技术及特殊的力学测量结构设计，在现有水平四分量钻孔应变仪基础上，研发并集成斜向和垂向线应变测量单元，实现水平4分量、斜向2分量、垂向1分量的线应变测量，实现地壳应变三维动态连续观测；构建钻孔附加应变解算物理模型，从方法上实现对地震构造带震前和同震响应非均匀形变特征进行观测，提高钻孔应变观测在地震预测和地球科学研究的应用效能。

本课题根据三维应力条件下的钻孔变形理论，结合竖井钻孔的结构，研发了垂向和斜向线应变测量单元，以现有RZB型（水平）分量式钻孔应变仪为基础，将垂向和斜向应变测量单元模块化集成，可同孔测量水平4分量（3个独立分量）、斜向2分量、垂向1分量，共计6个独立分量的线应变，实现了三维钻孔应变观测。研制的三维钻孔应变观测系统在四川珙县地震台实地安装，现已积累近2年的观测数据，由实测数据可知，水平、斜向、垂向应变测量单元均观测到清晰的固体潮汐，系统的测量灵敏度与各项指标达到课题设计要求。三维钻孔应变观测系统具有完全自主知识产权，已授权专利5项。