岩石受压状态的损伤分析

以损伤力学的方法对岩石在受压状态下的破坏行为进行了分析，损伤力学（CDM）方法近年来在金属、混凝土及复合材料等工程材料的蠕变、断裂等问题的研究中得到大量应用。损伤演变是物质内部结构的不可逆变化过程，损伤变量是与塑性变形一样的内变量，文中据实验数据推导出某类岩石的损伤变量演化曲线，以及损伤与应力的变化关系，以期用损伤学方法研究岩石变形的局部化行为。     

Highly Localized Vernacular Regionalization in the Allentown-Bethlehem Area,PA-NJ*

Yi-Fu Tuan's cognitive theory of the construction of place suggests the need for a higher level of resolution in research on American local vernacular regions. A survey-based case study of the Allentown-Bethlehem area demonstrates that municipal data can substantially refine an existing county-based delimitation by revealing previously undocumented regions and subregions, areas with mixed regional identity, and areas lacking regional identity. The resulting delimitations of subcounty vernacular regions are sufficiently precise to disclose a striking correspondence with area school districts.     

论边缘定位：玢岩型铁硫多金属矿床定位的动力学机制

通过庐枞中生代火山岩地区成矿时空结构的研究,提出了玢岩型铁硫多金属矿床定位的动力学——边缘定位机制,总结出该区的4种边缘定位形式和引起边缘定位的两方面动力学因素,最后建立了该区构造、火山—岩浆、岩性多因素控制的边缘定位模式.     

机载高分辨率SAR图像直接对地定位原理及精度分析

依据机载SAR成像的原理,给出了一种实用的机载SAR直接对地定位公式,并结合获取的高分辨率图像进行了定位纠正,取得了较好的效果。根据机载SAR图像对地定位的原理,推导了定位误差的传播公式,并进行了一些误差模拟研究。     

Viscous Energy Dissipation and Strain Partitioning in Partially Molten Rocks

We develop a steady-state fluid-mechanical analysis describingthe effect of strain partitioning on viscous energy dissipation.As observed in experimental studies of shear deformation ofpartially molten rocks, strain partitions when melt segregatesbecause viscosity is reduced in regions of elevated melt fraction.The equations derived here are based on parameters measuredin experiments, describing the evolution of melt distributionand rheological properties. We find that the dissipation dependsstrongly on the configuration of the melt-rich network of shearzones, including the average angle, volume fraction of meltand amplification of strain rate in the melt-rich bands. Minimain energy dissipation as a function of band angle develop, correspondingto configurations of melt networks that minimize the differencein mean stress between the band and the non-band regions. Wepropose that the organization of band networks occurs by theinterplay between strain localization and viscosity variationsassociated with melt segregation. The band networks maintaina steady-state angle during shear by continuously pumping meltthrough the network. The development of strain partitioningin melt-rich networks will modify the energetics of meltingand melt transport by efficiently extracting melt and reducingeffective viscosity. KEY WORDS: melt transport; rheology; self-organization; strain localization; strain partitioning     

Rheological and kinematical responses to flow of two-phase rocks

Numerical simulations have been performed to investigate the strain-dependent behaviour of rheological and kinematical responses to flow of two-phase rocks using the commercial finite-difference program FLAC2D. It was assumed that the two phases have Maxwell rheology. Plane strain and velocity boundary condition, which produces a simple shear deformation, were also assumed. Two types of geometries were considered: strong phase supported (SPS) and weak phase supported (WPS). We calculated strain-dependent variations of effective viscosity and partitioning of strain rate, vorticity and kinematic vorticity number during deformation in both SPS and WPS structure models.The results show that the strain-dependent behaviour is largely influenced by the geometry of the composite. SPS models show both strain hardening and strain softening during the simulations, with strain hardening preceding strain softening. A critical shear strain is necessary to begin the strain softening behaviour. Strain hardening and strain softening are accompanied by a reduction and an increase of the partition of strain rate into the weak phase, respectively. On the other hand, WPS models show only weak strain hardening and strain softening, being the strain-dependent behaviour close to a steady state flow. In addition, the following results are obtained on vorticity and kinematic vorticity number; (1) in both SPS and WPS models the partition of vorticity into weak phase increases with progressive shear strain, i.e. the strong phase becomes less rotational, (2) in SPS models weak inclusions changes from sub-simple shear to super-simple shear with progressive strain, whereas the strong matrix changes from super-simple shear to sub-simple shear, (3) in WPS models the strong inclusions with high viscosity contrasts are less rotational but can be in super-simple shear condition to high strains.The observed strain-dependent behaviours have been compared with previous proposed analytical models. The degree of agreement is variable. Balshin and Ryshkewitch–Duckworth models are only applicable to SPS models. Ji-generalized mixture rule model is applicable to both models.The results suggest that polyphase rocks with SPS structure during ductile shear deformation respond as strain softening materials, after an initial strain hardening stage that may drive to the strain localization into the material.     

On the physical model of earthquake precursor fields and the mechanism of precursors＇timespace distribution（Ⅲ）──anomalies of seismicity and crustal deformation and their mechanisms when a strong earthquake is in prep

Ｏｎｔｈｅｐｈｙｓｉｃａｌｍｏｄｅｌｏｆｅａｒｔｈｑｕａｋｅｐｒｅｃｕｒｓｏｒｆｉｅｌｄｓａｎｄｔｈｅｍｅｃｈａｎｉｓｍｏｆｐｒｅｃｕｒｓｏｒｓ＇ｔｉｍｅｓｐａｃｅｄｉｓｔｒｉｂｕｔｉｏｎ（Ⅲ）──ａｎｏｍａｌｉｅｓｏｆｓｅｉｓｍｉｃｉｔｙａｎｄｃｒ...     

Estimation of hypocentral parameters of local earthquakes when crustal layers have constantP-velocities and dipping interfaces

The paper describes an algorithm for estimating the hypocentral coordinates and origin time of local earthquakes when the wave speed model to be employed is a layered one with dipping interfaces. A constrained least-squared error problem has been solved using the penalty function approach, in conjunction with the sequential unconstrained optimization technique of Fiacco and McCormick. Joint confidence intervals for the computed parameters are estimated using the approach of Bard for nonlinear problems. These results show that when a hypocentre lies outside the array of recording stations and head waves from a dipping interface are involved, then its inclination must be taken into account for dip angles exceeding 5°.     

Development of shear localization in simulated quartz gouge: Effect of cumulative slip and gouge particle size

Frictional sliding experiments were conducted on two types of simulated quartz gouge (with median particle diameters 5 m and 25 m, respectively) at confining pressures ranging from 50 MPa to 190 MPa in a conventional triaxial configuration. To investigate the operative micromechanical processes, deformation texture developed in the gouge layer was studied in samples which had accumulated different amounts of frictional slip and undergone different stability modes of sliding. The spatial patterning of shear localization was characterized by a quantitative measurement of the shear band density and orientation. Shear localization in the ultrafine quartz gouge initiated very early before the onset of frictional sliding. Various modes of shear localization were evident, but within the gouge zoneR ₁-shears were predominant. The density of shear localization increased with cumulative slip, whereas the angle subtended at the rock-gouge interface decreased. Destabilization of the sliding behavior in the ultrafine quartz gouge corresponded to the extension ofR ₁-shears and formation of boundaryY-shear segments, whereas stabilization with cumulative slip was related to the coalescence ofY-shear segments to form a throughgoing boundary shear. In the coarse quartz gouge, the sliding behavior was relatively stable, probably because shear localization was inhibited by distributed comminution. Two different models were formulated to analyze the stress field within the gouge zone, with fundamentally different predictions on the orientations of the principal stresses. If the rock-gouge interface is assumed to be bonded without any displacement discontinuity, then the maximum principal stress in the gouge zone is predicted to subtend an angle greater than 45° at the interface. If no assumption on displacement or strain continuity is made and if the gouge has yielded as a Coulomb material, then the maximum principal stress in the gouge zone is predicted to subtend an angle less than 45°. If the apparent friction coefficient increases with overall slip (i.e., slip-hardening), then the Riedel shear angle progressively decreases with increasing shear strain within the gouge layer, possibly attaining a zero value which corresponds to a boundaryY-shear. Our quantitative data on shear localization orientation are in reasonable agreement with this second model, which implies the coefficient of internal friction to be about 0.75 for the ultrafine quartz gouge and 0.8 for the coarse gouge. The wide range of orientations for Riedel shear localization observed in natural faults suggests that the orientations of principal stresses vary as much as in an experimental gouge zone.