万顷良田建设工程系统分析

在分析当前经济社会发展的重点和经济社会发展与用地供需矛盾的基础上,采用系统分析法探讨万顷良田建设工程系统内涵,促进万顷良田建设工程的开展与实施.构建了万顷良田建设工程系统模型,揭示了万顷良田建设工程系统的核心、系统目标、系统功能和系统特征,提出了相应的政策措施和对策建议,对于理解工程建设内涵,顺利开展高质量的万顷良田建设工程具有一定的指导作用.     

河南省钼矿床赋存特征

通过对河南省钼矿床赋存特征的分析研究，总结出如下规律：1）河南省钼矿床属东秦岭-大别山钼成矿带的一部分；2）在地槽活动带的边缘区，构造岩浆岩带是钼矿床产出的有利场所；3）成矿母岩是主要控矿因素，同时也是最重要的找矿标志；4）区域巨大的燕山期花岗岩基是成钼小岩体的母岩，而成钼小岩体又是钼矿床的成矿母岩，三者在空间分布上具有高度的一致性。     

铜矿峪矿氧化矿石的性质特征

铜矿峪矿氧化矿石量1000多万t，主要分布在5号矿体中，属于难选矿石。从其物质成份、结构构造及铜的赋存状态(包括铜的栽体矿物、分配率、铜矿物的粒度分布特征)几个方面，详细论述了这部分氧化矿石的性质特征。     

有限元法在陷落区公路稳定性评价中的应用

来文研究了德兴铜矿185m水平中段陷落区工程地质特征,用有限元数值模拟法分析了通过陷落区公路的5个计算模型的位移变化规律及应力分布村征,最后对陷落区公路进行了稳定性评价。     

浅谈软土路基勘察设计质量对施工质量造价控制的影响

本文叙述了软土路基设计与钻探资料,处治效果和经济效益比较,供公路软基路基处理设计时进行方案选择工作中的参考.     

钨金成矿带地质特征和找矿方向分析

本文针对位于崇阳县南部,高枧乡东南约9km,行政区划隶属于崇阳县高枧乡东山村进行勘察。区内有12km简易公路经东山至高枧与崇阳至高枧三级公路相连,至崇阳县城公路里程60km,经崇阳至京广铁路赵李桥火车站105km,交通条件较好。经过详细的勘察之后,对钨金成矿带地质特征和找矿方向进行了详细分析。     

灵北——双目顶断裂带成矿地质特征及成矿预测

通过对灵北－－双目顶断裂带成矿地质的分析与研究，阐明该带上矿脉特征；矿床的等呓生；矿体的侧伏规律及侧伏与矿液流动方向的关系，从而预测新的成矿区。     

“珠江钢管”的路

“珠江钢管”的路广东省冶金工业总公司王庆华广东番禺珠江钢管有限公司高勤勤番禺──广东珠江三角洲经济区经济高速发展的新兴卫星城。原先这里的钢铁工业几乎空白。然而，近两年来在石基镇崛起的珠江钢管有限公司，却令人刮目相看。走出广州市往南，过了长长的洛溪大桥...     

大直径沉管灌注桩在高层建筑中的应用

本文通过工程实践，简要介绍在软土地基上应用大直径沉管灌注桩作高层建筑基础的情况；简述了试桩、设计、施工及桩的质量检测，对单桩承载力的影响；并对成极质量的评价等问题进行了探讨。     

福建省永安小陶锰矿矿床地质特征及其成因探讨

详细论述了福建永安小陶锰矿矿床的地质特征，包括矿体赋存状态、矿体顶底板岩性特征、矿石质量、矿石柱状与梳状构造特征；并简要介绍了矿床成因及找矿方向。     

Yield Stress of Super Soft Clays

Super soft clays can be defined as insensitive cohesive soils that have a water content higher than the liquid limit. It is difficult to define and measure the strength of these soils using conventional soil mechanics apparatus. It is proposed that the shear strength be determined using a rotary viscometer and be defined as the shear stress at zero strain (shear strain) rate in this test of viscosity. In this paper a number of potential methods to determine the shear strength or yield stress of super soft clays is considered. The yield stress of four super soft soils, each with varying water contents, have been measured using a rotary viscometer. The results of these tests together with published data are used to develop a relationship between the yield stress and the index properties of super soft clays.     

Void Ratio Estimation of Soft Soils Using Electrical Resistivity Cone Probe

Electrical properties of soils have commonly been used to estimate geotechnical properties. This paper introduces a new device, an electrical resistivity cone probe (ERCP), to determine the electrical resistivity of seashore soft soils and estimate void ratio in the field. The probe consists of inner and outer electrodes with a coaxial structure. The probe tip is conical to minimize disturbance during penetration. A four-terminal pair configuration is used to prevent electrical interference. The electrical resistance is measured during a consolidation test, penetration tests in a large-scale calibration chamber, and at two field sites. With the resistivity of soils and electrical resistivity of pore water extracted from undisturbed soils, the void ratio is estimated using Archie’s law. The void ratio estimated by the ERCP in an oedometer cell is almost the same as the volumetric void ratio of sand determined from consolidation tests. In addition, the void ratio profile obtained by the ERCP agrees well with the volume-based void ratio in a sand-clay mixture prepared in the calibration chamber. The void ratio profile estimated in the field is inversely proportional to the standard penetration testing N-value and the cone-tip resistance of the cone penetration test. This paper demonstrates that the ERCP may be an effective device for the estimation of the void ratio of seashore soft soils.     

Undrained Shear Strength of K0 Consolidated Soft Soils

On the basis of critical state soil mechanics, this study derives theoretical formulas for predicting the undrained shear strength of K0 consolidated soft soils in triaxial compression and extension. Although the modified Cam-clay model is often utilized to predict the undrained shear strength of soft clays, it is applicable mainly to isotropically consolidated soils. Because of the anisotropy under K0 consolidation, an inclined elliptical yield surface is chosen, which is different from those methods based on the original Cam-clay model. The inclined elliptical yield surface is testified to be appropriate to the K0 consolidated soft soil and results in a better prediction of undrained strength, especially for the triaxial extension test. It is concluded that the analytical solutions obtained in this paper are in good agreement with the available test results and back-analysis of slope failures. On the basis of the investigation of soil properties, a simple formula is proposed for calculating the mean undrained shear strength along the failure surface.     

Engineering Properties of Fibrous Peats

This state-of-the-art paper presents an interpretation of the permeability, compressibility, and shear strength of fibrous peats using data from laboratory tests on undisturbed block samples of two fibrous peats, as well as extensive laboratory and field data from the literature on fibrous peat deposits. Engineering properties of fibrous peats are significantly different from those of most inorganic soils. However, the same fundamental mechanisms and factors determine behavior of both inorganic soils and fibrous peats. Fibrous peat deposits possess very high initial permeability, typically 1,000 times the initial permeability of soft clay and silt deposits. Upon compression, the permeability of fibrous peats decreases dramatically, with a ratio of permeability change index to in situ void ratio equal to 0.25, as compared to 0.50 for soft clay and silt deposits. Fibrous peats display extreme compressibility to the increase in effective vertical stress, with compression index values right after preconsolidation pressure 5 to 20 times the corresponding compressibility of typical soft clay and silt deposits. Among geotechnical materials, fibrous peats display the highest ratios of secondary compression index to compression index, in the range of 0.05 to 0.07. The values of coefficient of earth pressure at rest for normally consolidated young fibrous peat deposits are in the range of 0.30 to 0.35, as compared to 0.45 to 0.65 for inorganic soils. The values of friction angle from triaxial compression tests for fibrous peats are in the range of 40 to 60°, as compared to less than 35° for soft clay and silt compositions. For fibrous peats, the ratios of undrained shear strength in compression to preconsolidation pressure are usually in the range of 0.50 to 0.75, as compared to 0.32 for soft clay and silt deposits. For surficial fibrous peat deposits the ratio of vane shear strength to preconsolidation pressure is near 1.0, as compared to 0.12 to 0.35 for inorganic soft clay and silt deposits. For fibrous peats, the ratio of undrained Young’s modulus to undrained shear strength is in the range of 20 to 80.     

Grouting in Difficult Soil and Weather Conditions

Several methods of soil grouting and conventional underpinning are used to stabilize subsoils and repair the foundations of three apartment buildings. Innovative cold weather compaction grouting techniques were used in difficult soil conditions to densify poorly compacted man‐placed fill and soft organic silts beneath building foundations. Penetration grouting using a Portland cement slurry and Pozzolan (flyash) is performed to reduce permeability of the upper subsoils and to fill ineffective and detrimental building perimeter drains. A gravel intrusion jacking method is used to further density upper soils in conjunction with conventional underpinning methods. The project is unique because: (1) Techniques were used that allowed the contractor to drill and densify loose fills and soft natural soils containing cobbles and boulders; (2) the contractor was able to perform grouting and underpinning under extremely adverse weather conditions by using special equipment; and (3) occupants were able to remain in buildings during remedial construction.     

Analysis of Soil Disturbance Associated with Mandrel-Driven Prefabricated Vertical Drains Using an Elliptical Cavity Expansion Theory

The installation of mandrel-driven prefabricated vertical drains and resulting disturbance of soft saturated clays are analyzed with a new elliptical cavity expansion theory. This formulated theory accounts for a concentric progression of elliptical cavities in an undrained condition and the large-strain effects in the plastic zone incorporating the modified Cam clay parameters. The total and effective stresses and excess pore water pressure in the soils surrounding the mandrel are predicted taking into account the mandrel installation rate, mandrel dimensions and the time factor. The theoretical variation of excess pore pressure is then compared with the results of large-scale consolidometer tests, which show that the estimated and measured pore pressures are almost the same. The plastic shear strain normalized by the rigidity index is then used to identify the zone of disturbance around the vertical drains. This formulation has been applied to a case history from the Muar clay region in Malaysia, and the results verify the usefulness of the method for determining the extent of the smear zone.     

Modeling Compression Behavior of Structured Geomaterials

The influence of the natural (or artificially induced) structure of a geomaterial on its compression behavior is investigated. An approach for modeling this influence for various structured geomaterials is proposed by using the disturbed state concept. An isotropic compression model is formulated on three basic assumptions. A special version of the proposed model is also described for situations where the compression is one-dimensional. The proposed compression model is used to simulate the behavior of a variety of structured geomaterials such as clays, sands, calcareous soils, clay-shale, soft rock, unsaturated soils, and soils artificially treated by adding chemical agents or mechanical reinforcement, and the model is evaluated on the basis of these simulations. A general discussion on the influence of the structure of geomaterials on their mechanical properties is also presented.     

Seismic Response of Liquid Storage Tanks Incorporating Soil Structure Interaction

A frequency domain method is presented to compute the impulsive seismic response of circular surface mounted steel and concrete liquid storage tanks incorporating soil-structure interaction (SSI) for layered sites. The method introduces the concept of a near field region in close proximity to the mat foundation and a far field at distance. The near field is modeled as a region of nonlinear soil response with strain compatible shear stiffness and viscous material damping. The shear strain in a representative soil element is used as the basis for strain compatibility in the near field. In the far field, radiation damping using low strain soil response is used. Frequency dependent complex dynamic impedance functions are used in a model that incorporates horizontal displacement and rotation of the foundation. The focus of the paper is on the computation of the horizontal shear force and moment on the tank foundation to enable foundation design. Significant SSI effects are shown to occur for tanks sited on soft soil, especially tanks of a tall slender nature. SSI effects take the form of period elongation and energy loss by radiation damping and foundation soil damping. The effects of SSI for tanks are shown to reverse the trend of force and moment reduction under earthquake loading as is usually assumed by designers. The reasons for this important effect in tank design are given in the paper and relate to the very short period of most tanks, hence, period lengthening may result in load increase. A comparison is made with SSI effects evaluated using the code SEI/ASCE 7-02. Period elongation is found to be similar for relatively stiff soils when assessed by the code compared with the results of the dynamic analysis. For soft soils, the agreement is not as good. Code values of system damping are found to agree reasonably well with an assessment based on the dynamic analyses for the range of periods covered by the code. Energy loss by material damping and radiation damping is discussed. It is shown that energy loss may be computed using the complex dynamic impedance function associated with the viscous dashpot in the analytical model. The proportion of energy loss in the translation mode compared to that dissipated in the rotational mode is addressed as a function of the slenderness of the tank. Energy loss increases substantially with the volume of liquid being stored.     

不同厚度连铸板坯的合理总轻压下量

板坯连铸合理总轻压下量是决定轻压下效果的重要工艺参数之一,采用数学模型手段对合理总轻压下量的定量计算进行了研究。通过建立2D铸坯凝固传热分析模型及轻压下过程2D热-力耦合模型,对比铸坯凝固末端枝晶间残余浓化钢水体积收缩与轻压下引起的糊状区压缩变形量,研究了铸坯厚度、轻压下起始位置处固相率等因素对给定钢种合理总轻压下量的影响。结果表明:铸坯厚度对合理总轻压下量有显著影响,厚度分别为150、230、300和400mm时,开始实施轻压下工艺时铸坯横截面中心节点固相率在0.7~0.3之间变化时,轻压下区间内的合理总压下量分别应为2.42~3.14、2.95~4.65、3.66~5.82和4.55~7.26mm。