排序方式： 共有15条查询结果，搜索用时 31 毫秒
1.
钙质砂抗剪强度特性的环剪试验 总被引：2，自引：0，他引：2
珊瑚礁沉积的钙质砂与石英砂的物理力学性质有较大差别。对取自南海岛礁的钙质砂进行了单次往返环剪试验以分析钙质砂的抗剪强度特性,试验中考虑了相对密实度和竖向应力对结果的影响,并与相同级配和试验条件下的石英砂进行对比分析。结果表明：钙质砂正向剪切时应力-位移曲线为软化型,具有明显的残余强度特性,而反向剪切时则表现为硬化型,正向和反向剪切强度基本一致;石英砂正向剪切和反向剪切均表现为软化型。钙质砂正向剪切和反向剪切残余强度与峰值强度的比值在0.75～0.93之间;石英砂正向剪切和反向剪切残余强度与对应峰值强度的比值在0.89～0.96之间。相同级配和试验条件下,钙质砂残余强度均大于石英砂,且强度比值基本保持在1.05～1.3之间。在100、200 kPa竖向荷载作用下,钙质砂0.5～2.0 mm的颗粒发生了破碎,破碎率分别为4%和6%。 相似文献
2.
3.
为研究土钉支护结构体系的抗震性能,设计并完成了土钉支护边坡1：12比尺的振动台试验,研究了土钉支护边坡的动力反应特征和规律。结果表明：土钉支护边坡坡面的最大变形主要发生在边坡坡腹处,坡顶与坡趾的变形相对较小;增大土钉倾角会增大边坡的侧向位移,增加土钉长度以及减小土钉间距则会减小边坡侧向位移;土钉支护最大作用带基本位于土钉支护区的中前部,呈折线形,与计算假设的圆弧形不同,而且该作用带与滑裂面的位置并不相同;边坡土体中部和下部的加速度放大系数较小而且比较接近,边坡上部土体的加速度放大系数则较大。 相似文献
4.
位于浙西北安吉港口的铅锌银(钼)多金属矿床,是新近在钦杭成矿带东北缘发现的一个产于大陆环境且具较好前景的矿床.文章通过对矿区坞山关杂岩体三套岩性单元、细粒花岗岩和方铅矿铅同位素的全面对比研究,探讨了矿床的铅物源岩浆岩.矿区中的方铅矿为含较高放射性成因铅的J-型铅,在铅同位素的V1-V2和△γ-Δβ图解中,本次研究的样品分别落入华南和岩浆作用上地壳混合地幔铅范围,显示出方铅矿与华南地球化学省壳幔混合岩浆作用的密切关系.矿区铅锌矿体的方铅矿铅同位素比值显示其具有共同的物质来源,并基本保持了细粒花岗岩206Pb/204Pb值的特征,而207Pb/204Pb值具有坞山关杂岩体和细粒花岗岩混合的特征,208Pb/204Pb和208Pb/206Pb值则仅显示出与细粒花岗岩最相近.方铅矿铅同位素比值特征和比值等值线分布形式显示,铅主要来源于细粒花岗岩,杂岩体对铅成矿贡献了少量的206Pb和207Pb,矿区地层对铅成矿贡献了一定的208Pb.安吉矿区进一步针对铅的找矿工作围绕细粒花岗岩展开,取得成果的可能性更大. 相似文献
5.
《Soil Dynamics and Earthquake Engineering》2012,32(12):1711-1723
This paper presents a coupled lumped mass model (CLM model) for the vertical dynamic coupling of railway track through the soil. The well-known Winkler model and its extensions are analysed and fitted on the result obtained numerically with a finite–infinite element model in order to validate the approach in a preliminary step. A mass–spring–damper system with frequency independent parameters is then proposed for the interaction between the foundations, representing the contact area of the track with the soil. The frequency range of track–soil coupling is typically under 100 Hz. Analytical expressions are derived for calibrating the system model with homogeneous and layered half-spaces. Numerical examples are derived, with emphasis on soil stiffness and layering. The dynamic analysis of a track on various foundation models is compared with a complete track–soil model, showing that the proposed CLM model captures the dynamic interaction of the track with the soil and is reliable to predict the vertical track deflection and the reaction forces acting on the soil surface. 相似文献
6.
粗粒土等压固结与K0固结三轴试验比较 总被引：1，自引：0，他引：1
对某堆石坝覆盖层砂卵砾石料进行了不同干密度试样中型三轴试验,试验包括常规各向等压固结的三轴排水剪试验（CID试验）和各向不等压（K0）固结的三轴排水剪试验（CK0D试验）,对试验结果进行对比分析,研究2种试验方法对试验结果的影响。结果表明,2种试验所得到的应力—应变关系曲线总体规律比较一致,大小略有差异,CK0D试验的剪胀性比CID试验明显;不同围压下,2种试验的偏应力峰值差异（相对峰值）平均幅值为3.9%;对应3种密度（2.17、2.22、2.40g/cm3）,CK0D试验各围压下的平均内摩擦角分别比CID试验的内摩擦角大0.88°、0.48°、0.43°;随着密度增大,2种试验的强度均显著增大,且强度指标随密度近似线性增大。列出并比较了2种试验的邓肯模型参数,两者没有显著的差异。 相似文献
7.
An experimental research was conducted to determine the corrosion and bearing capacity of a reinforced concrete (RC) slab at different ages in a marine environment. Results show that the development of corrosion-induced cracks on a slab in a marine environment can be divided into three stages according to crack morphology at the bottom of the slab. In the first stage, cracks appear. In the second stage, cracks develop from the edges to the middle of the slab. In the third stage, longitudinal and transverse corrosion-induced cracks coexist. The corrosion ratio of reinforcements nonlinearly increases with the age, and the relationship between the corrosion ratio of the reinforcements and the corrosion-induced crack width of the concrete is established. The flexural capacity of the corroded RC slab nonlinearly decreases with the age, and the model for the bearing capacity factor of the corroded RC slab is established. The mid-span deflection of the corroded RC slab that corresponds to the yield of the reinforcements linearly increases with the increase in corrosion ratio. Finally, the mechanisms of corrosion morphology and the degradation of the mechanical properties of an RC slab in a marine environment are discussed on the basis of the basic theories of steel corrosion in concrete and concrete structure design. 相似文献
8.
This study was aimed at evaluating the mechanical and pH-dependent leaching performance of a mixed contaminated soil treated with a mixture of Portland cement (CEMI) and pulverised fuel ash (PFA). It also sought to develop operating envelopes, which define the range(s) of operating variables that result in acceptable performance. A real site soil with low contaminant concentrations, spiked with 3000 mg/kg each of Cd, Cu, Pb, Ni and Zn, and 10,000 mg/kg of diesel, was treated with one part CEMI and four parts PFA (CEMI:PFA = 1:4) using different binder and water contents. The performance was assessed over time using unconfined compressive strength (UCS), hydraulic conductivity, acid neutralisation capacity (ANC) and pH-dependent leachability of contaminants. With binder dosages ranging from 5% to 20% and water contents ranging from 14% to 21% dry weight, the 28-day UCS was up to 500 kPa and hydraulic conductivity was around 10−8 m/s. With leachant pH extremes of 7.2 and 0.85, leachability of the contaminants was in the range: 0.02–3500 mg/kg for Cd, 0.35–1550 mg/kg for Cu, 0.03–92 mg/kg for Pb, 0.01–3300 mg/kg for Ni, 0.02–4010 mg/kg for Zn, and 7–4884 mg/kg for total petroleum hydrocarbons (TPHs), over time. Design charts were produced from the results of the study, which show the water and/or binder proportions that could be used to achieve relevant performance criteria. The charts would be useful for the scale-up and design of stabilisation/solidification (S/S) treatment of similar soil types impacted with the same types of contaminants. 相似文献
9.
一种基于数值应力场的强度各向异性边坡稳定性分析方法 总被引：1，自引：0，他引：1
提出了一种基于数值应力场下的边坡临界滑动面和临界坡高的分析方法。该分析方法首先利用有限元得到边坡内部较为精确的应力场,再通过在边坡内部模拟类似于链式反应过程中粒子产生和运动规律,在此基础上完成临界滑动面的搜索。主要结论如下：（1）提出了一种基于数值应力场的边坡临界滑动面的搜索方法,该方法可在不对边坡滑动面形状和位置进行干预的情况下完成潜在破坏路径的搜索。（2）通过对算法中区域与边界、激发源、产物扩散路径、路径权值4方面要素进行合理控制,可使算法在具有较高精度的同时又能保证较好的分析效率。（3）算法能较为方便地考虑真实应力条件下地层强度各向异性对边坡稳定性的影响,并能对临界坡高进行很好的分析。（4）通过具体算例对本文算法的计算结果进行验证,将所得结果与PSO和Monte Carlo两种方法得到结果进行对比,对本文方法的可靠性进行了验证,取得了较好的效果。 相似文献
10.
在总结前人关于海水入侵危险性评价研究的基础上,提出了基于GIS的层次分析法和模糊综合评判法,并以深圳市宝安区为例建立了海水入侵危险性评价体系.首先研究了宝安区海水入侵现状;然后选取了含水层结构、地下水氯离子质量浓度、地下水水位、地形地貌、与海岸线距离、地下水开采、土地利用类型7个评估因子;再利用层次分析法确定了各评估因子的权重,根据模糊综合评判法的原理,经过模糊运算得到危险性级别;最后运用GIS空间分析功能实现了海水入侵灾害危险性区划.结果表明:评价结果与该地区的海水入侵现状吻合较好.高危险区和较高危险区面积达107.77 km2,占研究区总面积的46.7%. 相似文献