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791.
航磁梯度资料在金矿地质填图和成矿预测中的应用 总被引:3,自引:0,他引:3
通过对冀东和冀北地区大比例尺(1:25000)航磁梯度资料的分析研究发现,航磁梯度与常规的航磁总场相比,在金矿地质填图中可以更准确地划分不同地层分界、确定火成岩的分布范围以及断裂构造带的平面位置等。总结了金矿床上航磁梯度异常的变化规律。最后,利用包括航磁梯度在内的综合航空物探信息,对冀东渠子地地区进行了金矿预测研究,取得了较好的地质效果。 相似文献
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混凝土集料级配与分形 总被引:13,自引:0,他引:13
若尺度范围足够宽,分表维数D〈3时,破碎体分形与指数a〈3的筛下幂式一致;D〉3时,破碎体分形符合筛上幂型分布。统计分析表明,建筑用砂符合D〉3的分形,指数β很好地反映了砂的级配与粗细,可作为评估指标使用;碎石集料分形符合筛下幂型分布。 相似文献
794.
Nguyen Ngoc Truc Lena Mihova Toshifumi Mukunoki Duc Minh Do 《Marine Georesources & Geotechnology》2020,38(1):23-39
AbstractThis study conducted a series of laboratory experiments and established numerical models on selected undisturbed soil samples in the Red River Delta (RRD) to determine the effect of change in soils intruded by saline water. The variation in the technical parameters of soils was verified in soils fully saturated by solution of four salt concentrations, that is, 0.0, 9.9, 19.8, and 33.0?g/L. Results show that the content and composition of clay minerals in cohesive soils before and after saline intrusion are unchanged. The same finding is obtained for clay after removing absorbed water layer by using a centrifuge apparatus. The zeta potential and settlement velocity of soils in the RRD increase when salt is added to the saturated solution. Similarly, the deformation of soils increases proportionally with the salt concentrations of that solution. This result is attributed to the linear decrease in deformation modulus. The decrease in modulus versus salinities is nearly consistent for pressure stages from 100 to 400?kPa. The safety factor of bearing capacity also decreases linearly with salinities. The decrease reaches 12.5–16.3% when soils are in the maximum saline solution. All these changes are considered as the degradation of soils in saline media. 相似文献
795.
A Modified approach for calculating dynamic shear modulus of stiff specimens by resonant column tests 总被引:1,自引:0,他引:1
1 Introduction Study of the shear modulus to represent the static and dynamic properties of geotechnical materials is a basic topic in the geotechnical engineering and many researchers (Hardin and Black, 1966; Zhang and Li, 2003; Richard and Richard, 1988; Yuan et al, 2000; Soo et al, 1995) have investigated this phenomenon. The resonant column device provides a powerful tool for testing the shear modulus and damping ratio of the soil-like materials. In 1984, the ?rst resonant column device… 相似文献
796.
Analytical equations for the moment–rotation response of a rigid foundation on a Winkler soil model are presented. An equation is derived for the uplift-yield condition and is combined with equations for uplift- and yield-only conditions to enable the definition of the entire static moment–rotation response. The results obtained from the developed model show that the inverse of the factor of safety, χ, has a significant effect on the moment–rotation curve. The value of χ=0.5 not only determines whether uplift or yield occurs first but also defines the condition of the maximum moment–rotation response of the footing. A Winkler model is developed based on the derived equations and is used to analyze the TRISEE experiments. The computed moment–rotation response agrees well with the experimental results when the subgrade modulus is estimated using the unload–reload stiffness from static plate load–deformation tests. A comparison with the recommended NEHRP guidelines based on the FEMA 273/274 documents shows that the choice of value of the effective shear modulus significantly affected the comparison. 相似文献
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岩体弹性模量的尺寸效应初步研究 总被引:3,自引:0,他引:3
通过建立单轴压缩情况下含裂纹岩石试件的功能平衡方程,运用概率统计的方法,推导了岩体弹性模量尺度效应的表达式,揭示了岩体弹性模量尺度效应的内部结构本质。 相似文献