塔克拉玛干沙漠腹地风沙土的物理力学性质

风沙是形成于干旱、半干旱区的一种特殊性质的土 ,其力学性质不同于一般土体 ,结构松散性为其最主要的特点。本文通过对塔克拉玛干沙漠腹地风沙土样进行的试验 ,获得了风沙土基本力学参数 :压缩模量为 5 0 0～ 14 2 86MPa ,是一种低压缩性土 ;为 31°5 5′～ 36°19′ ;风沙土存在结构力 ,其力学效应相当于粘聚力 ,数值在 0 6～ 9 3MPa之间。     

Determination of unconfined compressive strength and Young's modulus of porous materials by indentation tests

The formation of a compacted zone under the indenter seems to be the major factor controlling the indentation process in porous rocks. In the case of very porous materials, where the pore structure fails and deformation (by structural collapse) proceeds with almost no increase in the applied load and with very limited damage to the surrounding material, no chipping is observed. The extent of the compacted zone is controlled by the porosity of the material and by the strength of its porous structure. This paper presents an interpretation model developed by the authors to obtain the uniaxial compressive strength of porous materials from the results of indentation tests. It is based on the model proposed by Wilson et al. (Int. J. Mech. Sci., 17, 1975, 457) for the interpretation of indentation tests on compressible foams and on an estimation by the authors of the extent of the compacted zone under the indenter. The results of indentation tests can also be used to obtain the Young's modulus of the material with a model proposed by Gill et al. (Proceedings of the 13th Canadian Symposium on Rock Mechanics, 1980, 1103). Uniaxial compression and indentation tests have been performed on artificial porous materials showing porosities varying between 44 and 68%. The uniaxial compressive strength values obtained from both types of test show a very good agreement. For the Young's modulus, the values obtained from the two types of test are different but the variation of the moduli with porosity is the same. Finally, a parameter called permanent penetration modulus is proposed as a means of characterizing the uniaxial compressive strength of porous materials.     

The Gibbs energy formulation of the α, β, and γ forms of Mg2SiO4 using Grover, Getting and Kennedy's empirical relation between volume and bulk modulus

 The empirical linear relation between volume and logarithm of bulk modulus of a material, discovered by Grover, Getting and Kennedy is taken as the basis for our equation of state. Using the latest experimental information on the adiabatic bulk modulus, the equation of state is applied to the three polymorphs of Mg₂SiO₄ to develop a consistent dataset of their thermodynamic properties in the temperature range of 200–2273 K and a pressure range of 0.1 MPa–30 GPa. The results imply that the bulk sound velocity contrast (v ^β−v ^α)/v ^α increases with temperature along the α–β phase boundary and reaches the value 8.9% at 13.5 GPa, a pressure equivalent to 410 km depth in the Earth. The bulk sound velocity contrast (v ^γ−v ^β)/v ^β decreases with temperature along the β–γ phase boundary and becomes less than 0.7% at temperatures and pressures equivalent to those associated with the 520-km seismic discontinuity in the Earth. Received: 1 August 2000 / Accepted: 1 March 2001     

中国古代大木作结构斗栱竖向承载力的试验研究

为探讨中国古代大木作结构斗栱在竖向地震作用下隔震、减震机理以及相应的竖向极限承载能力，对三个缩尺比为l／3．52的二等材计心造两跳五铺作斗栱进行了竖向荷载作用下的试验研究，得出了相应的P-△曲线。结果表明，在竖向荷载作用下：(1)斗栱结构特性可视为变刚度线弹性变化，可用单自由度的质量-弹簧-阻尼器模型来说明；(2)斗拱的破坏始于华栱中部的塑性变形和劈裂；(3)在地震动过程中，其运动的竖向传递率大约为0．019，说明斗栱在减小结构地震响应方面发挥了重要作用；(4)在正常使用阶段，斗拱的内力与变形不超过其极限承载力的l／7左右，强度裕度很大。这保证了很多中国古代木结构能够抵御许多强烈地震作用并且矗立千年而不倒。     

弹性模量、波速与应力的关系及其应用

为充分了解不同尺度地质系统的岩石动力学特征,更好利用不同规模勘探资料有效解释地质系统的特征,在岩石物理实验对岩石弹性模量、波速与应力的关系进行研究总结的基础上,探讨野外实际地震勘探中地震波速与地应力的关系。研究表明,岩石、岩体或地质系统是多相(固液气)、多种矿物、各种构造的综合体,不论尺度如何均可以用多重介质孔隙裂隙地质模型描述,而波速是一定尺度不均匀地质体的等效波速,在一定地质条件下,各种尺度介质波速、岩石弹性模量与有效应力存在依存关系。坚硬的岩石通常很脆,如果岩石处于很大的应力之下,应力的释放将在岩石中产生微裂隙,微裂隙会降低地震速度。只要把岩石恢复到原来的应力状态就可能消除所引发的微裂隙。在岩体未达到破坏时,应力越大,波速愈高。压力释放引发的微裂隙有助于现场确定最大/最小水平应力方向,波速的椭圆长轴即为主应力方向。而上覆地层压力不变(或变化很小),净储层压力的影响正好与储层压力对地震特性的影响相反。随着净储层压力的增加,所有岩石的地震特性都增高。这种增高的量级取决于若干其它的因素(孔隙形状、孔隙度、孔隙流体、岩性等等)。不论野外地震勘探还是实验研究,地震波速与地应力的一致性为地质系统的正反演解释提供了宏观控制依据:通过测量弄清     

新疆博斯腾湖东泵站地基土的工程特性

通过对博斯腾湖东泵站地基土的各项物理力学性质指标分析,对中细砂层受外力或地震的作用下,发生振动液化的可能性以及对东泵站厂房基础稳定性进行了评价,确定合理参数,具有重大意义。     

倾斜地层地震液化和滑移的有限元分析

应用饱和多孔介质动力学分析倾斜地层的土壤动力线性反应、液化和液化滑移问题，地下水位上的地层简化为单相介质层，饱和夹砂层看作是两相介质，水是可压缩的，采用双曲线非线性本构关系，考虑了砂土的剪胀性、刚度退化、滞回特性和土水相对运动等因素。基于土力学模型，建立了适用于分析非自由场地液化的动力方程组，基于是否考虑发生渗流问题，同时建立了两种离散形式：一种是以土骨架位移和水位移为未知量的矩阵方程，另一种是以土骨架位移、水位移和孔隙水压力为未知量的矩阵方程，初步分析了适用于多孔介质波动模拟的离散模型的人工边界问题，形成的方法将有助于问题的解决。     

An equivalent linear algorithm with frequency- and pressure-dependent moduli and damping for the seismic analysis of deep sites

The seismic analysis of soil deposits is most often carried out with an iterative computational scheme, proposed by Seed and Idriss, in which inelastic effects are only approximately modeled through soil degradation curves. Laboratory experimental data indicate that for highly confined materials, the standardized reduction curves commonly used overestimate the capacity of soils to dissipate energy. This paper first presents the results obtained with a simple four-parameter constitutive soil model, which when used to simulate cyclic loading, produces results that agree well with available laboratory experiments for soils under arbitrarily large confining pressures. Thereafter, a frequency- and pressure-dependent iterative algorithm for seismic amplification is proposed, which provides time histories that match well the results obtained with a true non-linear model. Finally, the modified linear iterative analysis is successfully used for the seismic analysis of a 1 km deep model for the Mississippi embayment near Memphis, Tennessee, and a class-A prediction of the seismic amplification in Treasure Island during the Loma Prieta earthquake.     

Development of a high modulus paste fill using fine gold mill tailings

Summary In the mining industry today there is some caution about using fine tailings as a backfill material. Traditionally, hydraulic backfill has only used the coarse fraction of tailings, excluding the fines by a classification process. With the development of paste fill, the percentage of fine tailings being sent underground has increased, but still remains low due to the high percentages of sand and gravel which usually make up these fills. Sand and gravel have been added to paste fills to aid pumpability and to increase fill strength and stiffness. This leaves the remainder of fine tailings destined for surface disposal. The main focus of this paper is to evaluate what effect the addition of fine gold mill tailings in the form of agglomerated tailings pellets has on the strength and stiffness characteristics of a total tailings paste fill. The purpose is to create a high modulus fill which is made up entirely of fine tailings. A constant slump design of 20 cm (8 in) was used for each mix. Various binder dosages, curing periods and combinations of pellet to tailings ratio were studied. Raw fill slump and density, and cured fill compressive strength and modulus of elasticity were also examined. Results from the above study indicate that agglomerated tailings paste fill (ATPF) has superior strength and stiffness characteristics. Compressive strengths were enhanced while the modulus of elasticity values was tripled when compared to total tailings paste fills of the same binder content and consistency. ATPF minimizes the surface disposal of tailings and maximizes the utilization of fine tailings underground as a useful backfill material.     

人工冻土声波参数试验研究

用ＳＹＣ－２型声波探测仪，对取自淮南矿区井下冻粘土，冻砂土进行了测定。其声波纵横波速振幅衰减系数及动弹模与冻土温度、含水量、容重的关系均用于幂指数形式较好地描述。其中容波速，动弹模及振衰减的影响最大；其次为温度、含水量；冻土振幅度衰减系数对其物理参数变化的敏感性大于波速。另外还研究了冻粘土与冻砂土怕波特性差异、截载大小及加载时间对冻土怕特性影响。