岩体结构力学岩体工程地质力学的新发展

本文从岩体工程地质力学角度, 研讨了岩体结构力学的意义, 地位与作用。作者就个人的认识, 将岩体结构力学的理论特点, 概括为五个方面, 即再变形和再破坏, 岩体结构的控制作用、岩体结构控制论、赋存环境以及关于岩体的多种力学介质和力学模型构成的力学体系。     

结构动力模型试验相似理论及其验证

通过几何比尺为2的两个有机玻璃模型的结构动力试验，验证了结构动力模型试验的弹性相似律和弹性力一重力相似律。得到了以下结论：(1)大小模型频率符合相似律，一阶频率误差为2．7％、4．1％，二阶频率误差为O、6．05％。弹性相似律比弹性力一重力相似律更适合于频率预测的试验。(2)大小模型的加速度、应变符合相似律，弹性相似律的加速度误差为-1．55％～8．75％，应变误差为O．377％～7．297％。弹性力-重力相似律的加速度误差为3．07％～4．158％，应变误差为6．849％～12．959％。(3)不同相似律大小模型的时问比尺吻合很好。加速度与应变时程曲线的波形一致，既无漏峰也无错峰。     

CHARACTERIZATION OF DEFORMATION AND X-RAY PETROFABRICS IN THE MIDDLE PART OF THE WAHONGSHAN FAULT ZONE, QINGHAI PROVINCE, NORTHWESTERN CHINA

The Wahongshan fault zone in Qinghai province is one of the most important faults in westem China. In this paper, deformation and X-ray petrofabrics have been studied in the middle segment of the fault. The results show that the formation of the fault zones can be divided into two major stages: ductile shear deformation stage and brittle deformation stage. The early stage ductile shearing leads to the formation of the NW-NNW trending mylonite zones along the fault, which is intensely cut by the late-formed brittle faults. X-ray petrofabrics of rocks near the faults indicate that the minerals in the tectonites show a great degree of orientation in the alignment. The quartz, which is a very important mineral in the tectonites, is deformed by basal face gliding or near basal face gliding, and sometimes by prismatic face sliding, which indicates that the rocks are deformed in epithermal to mesothermal or mesothermal environment, and the dynamic recrystallization also plays an important role in the formation     

GEOCHEMICAL CHARACTERISTICS OF GRANITES AND ITS STRUCTURAL GENETIC ENVIRONMENT IN THE NANDAN-HECHI METALLOGENETIC BELT, NORTHWEST GUANGXI

The Nandan-Hechi metallogenetic belt is the most important tin-polymetallic producing district in China, and is the location of the Dachang super-large tin deposit. Based on the detailed field investigation and isotopic data, the stages of magmatic activity in the Nandan-Hechi metallogenetic belt have been lined out in this paper. Through the study about the geochemical characteristics of different granites, and by using ω(Al2O3)-ω(SiO2), ω(TFeO)/[ω(TFeO) ω(MgO)]-ω(SiO2), AFM, ACF and Rb-Yb Ta, Rb-Y Nb,Ta-Yb, Nb-Y discrimination diagrams in combination with regional geological setting analysis, the authors carried out analyses about the structural environment for the formation of the granites, and discussed the structural environment and dynamic setting for the large scale mineralization in this area. Our study indicates that the majority of the granites in Nandan-Hechi metallogenetic belt belong to the POG type,while the later stage alaskite belongs to the RRG CEUG type. The granites were formed at the stage of structural transformation from postorogenic phase to intraplate setting. But the major structural environment is characterized by steady regional extension. The formation age for the granites coincides with the time for this transformation, and this translation environment is favored for large-scale metallogenesis.     

柴达木盆地新生代不同层次构造特征

应用柴达木盆地地震、非地震资料进行综合解释研究发现,新生代盆地深、浅层构造存在较大差异,盆地沉积在不同时期受到不同构造格局的控制。古近系受近东西向构造控制,新近系受北西向构造控制,显示了柴达木盆地新生代为不同时期受不同方向构造控制的大型叠合盆地。盆地地层深、浅层构造变形特征不同,深层表现为陡倾的逆冲断裂构造,以断块构造为主要特征;中浅层表现为滑脱褶皱与滑脱断裂构造;地表在背斜核部发育斜列展布的正断层构造。盆地经历了多旋回沉积和多方式的后期改造,不同的构造组合形成了不同的储油气构造模式,认识这一点对于盆地深层的油气勘探,特别是寻找隐蔽油气藏具有重要意义。     

Structural features and petroleum geology of the fold-thrust belt in the southern Tarim basin, China

The west Kunlun fold-thrust belt (WKFTB) and the Altun fold-thrust belt (AFTB) are respectively located in the southern margin of the Tarim basin, NW China. The analyses of typical structures and regional dynamics of the fold-thrust belts reveal their different structural and petroleum features and mechanisms. WKFTB differs from AFTB by abundant fault-related folds and triangles zones, and was formed by northward extrusion of the west Kunlun orogen. AFTB was affected synchronously by northward extrusion of the Altun orogen and the sinistral strike-slipping of the Altun Fault, so it is characterized by the minor scale and the monotonous structural styles. The Aqike anticline and the Aqike fault, of which the strikes are orthogonal to the strike of the fold-thrust belts, are regarded as the adjustive structures between both of the fold-thrust belts. The oil-gas pools of WKFTB develop mainly in the faulted-related anticline traps, but the oil-gas pools of AFTB develop mainly in the low fault-block and anticlines traps related with the paleo-uplifts. There are different exploration countermeasures for both of the fold-thrust belts.     

Seismic structural control using an electric servomotor active mass driver system

This study investigates an electric‐type active mass driver (AMD) system for structural vibration control. Composed primarily of an electric servomotor and a ball screw, the electrical AMD system is free from noise problems, oil leakage, and labor‐intensive maintenance that commonly are associated with hydraulic AMD systems. The desired stroke amplification of the mass and the power demand of the servomotor can be adjusted via the ball screw pitch, which in turn affects the effectiveness and efficiency of the system. Meanwhile, an instantaneous optimal direct output feedback control algorithm is adopted. Numerical simulation is performed using a five‐story steel frame as the object structure under the conditions of the 1940 El Centro earthquake. The AMD system proves to be effective and efficient within a certain range of the ball screw pitch. The reductions of the peak responses can reach as high as 70% if properly designed. Requiring only the velocity measurement of the top floor for on‐line feedback control, the proposed control algorithm is recommended for practical implementation. Copyright © 2004 John Wiley & Sons, Ltd.     

The seismic shear of ductile cantilever wall systems in multistorey structures

The distribution of seismic base shear demand among ductile flexural cantilever walls, comprising the lateral load resisting system of a multistorey building, is studied. It is shown that the base shear force demand depends on the sequence of hinge formation at the wall bases, and this in turn depends on the relative wall lengths. Hence, the routine elastic approach in which the shear forces are allocated per relative flexural rigidity or (when some consideration is given to plastic hinge formation) to moment capacity at the wall base, may appreciably underestimate the shear force demand on the walls, particularly the shorter (usually the more flexible) ones. A simple procedure yielding the results of ‘cyclic’ pushover analysis is proposed to predict the peak seismic wall forces for a given total base shear when plastification is confined to the wall base. The effects of plastic hinges developing at higher floors on (1) shear distribution among the walls and (2) the in‐plane floor forces are also considered. Two numerical examples are presented to demonstrate the main points made. Copyright © 2004 John Wiley & Sons, Ltd.     

成都市区域化探深层样品元素异常与物探重、磁异常及遥感解译构造的关系

通过深层样化探异常与物探重力、航磁和遥感解译关系的研究,认为深层样元素异常是由隐伏构造指示元素Au、Hg,与重力负异常有关的酸性岩元素Sn、Be、F、Y,与航磁正异常有关的基性岩元素Fe、Co、Ni、V、Cr和与地层有关元素Cd、C、Tl四部分组成;解释了深层样元素异常的原因,开拓出区域化探与区域物探、遥感解译相结合的新路。     

大别山南部宿松磷矿含磷地层的时代归属与变形特征及其构造评价

根据对大别山南部宿松磷矿含磷地层的区域分布、地层序列、时代归属、构造变形的系统研究,提出磷矿层属震旦系的新认识。含磷岩系经受了两次强烈的变形改造,原始层理经过了强烈改造,宿松磷矿构成总体包络面呈北西西走向、向南倾斜的褶皱化单斜。矿层的多层化、尖灭复合和加厚现象等主要受构造的控制,而非完全受古地形的控制。用褶皱的观点对原先勘探剖面中的磷矿体进行了重新圈连,籍以指导磷矿的调查、评价和开采。最后对磷矿分布的古地理特征进行了讨论,并从构造的观点对磷矿进行了评价。