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1.
冻融循环作用是寒区土体力学性质改变的主要影响因素之一。为研究冻融循环作用下寒区冻结掺和土料的动力特性(包括动变形和动强度),以寒区高土石坝砾石掺和土坝料为研究对象,采用低温振动三轴材料试验机,对不同冻融循环次数(0、5、20次)下的冻结掺和土试样进行不同围压和不同动应力幅值比条件下的低温动力循环三轴试验,探讨冻融循环作用对冻结掺和土料的动应力-动应变关系,体变、滞回曲线,轴向累积应变,动回弹模量,残余应变以及动强度的影响。结果表明:随着冻融循环作用的增加,冻结掺和土料的动应力-动应变曲线和体变曲线逐渐稀疏,且试样达到破坏应变的振动次数呈线性减小。通过对不同冻融循环次数下冻结试样的滞回曲线、轴向累积应变、残余变形的研究,发现冻融循环作用使得试样抵抗变形的能力下降。随冻融循环次数的增加,试样的动回弹模量减小,动强度逐渐降低,试样更容易发生破坏。研究结果较好地解释了冻结掺和土料在冻融循环作用下动力变形的机制,可为基于动力变形控制的寒区工程基础设计提供科学参考。 相似文献
2.
超细尾砂已成为充填材料的主要来源。为了便于充填料浆配合比设计与强度预测,基于超细料浆微观结构,提出用固体填充率表征充填料浆结构密实程度。选用某矿山超细尾砂进行了63组配合比强度试验。研究结果表明：固体填充率和水灰比与充填体无侧限强度分别呈指数函数和负幂函数关系。采用Pearson理论对试验样本进行相关性分析,结果表明：固体填充率与水灰比相互独立。在此基础上,建立了超细尾砂胶结充填体双变量强度计算模型,模型计算值与试验值的误差在7%以内。进行了超细尾砂胶结体强度随养护时间增长的试验,基于试验数据拟合规律,提出了强度龄期数学模型,建立了三变量强度计算公式。模型能准确预测矿山充填体强度,且能有效指导矿山充填料浆设计。 相似文献
3.
利用测温法和核磁共振法测量了不同浓度典型盐溶液（NaCl、Na2CO3）饱和重塑粉土的冻结温度及冻结特征曲线，并与不同浓度的NaCl、Na2CO3纯溶液作对比分析，研究初始含盐量对冻结温度及未冻水含量的影响。结果表明：土样冻结温度随初始含盐量的增加而逐渐降低；相同浓度NaCl溶液饱和土样的冻结温度低于相应纯溶液的冻结温度，但相同浓度 （<0.6 mol/L）Na2CO3溶液饱和土样的冻结温度却比纯溶液的冻结温度高；同一负温下，土样中未冻水含量随NaCl初始含盐量的增加而增多，但随Na2CO3初始含盐量的变化不明显。通过机制分析，表明盐类型和含盐量对土水势具有不同的影响。基于改进的广义Clapeyron方程，将含盐分土冻结温度表达式引入未冻水含量预测模型，得到了能够考虑不同含盐量影响的土体未冻水含量的定量表达，并与实测数据进行对比，验证了该模型能够较为合理的预测不同温度下含盐土体的未冻水含量。 相似文献
4.
《岩土力学》2017,(1):101-108
采用MTS815岩石力学试验系统与自制的胶结充填体制作装置,对骨架颗粒满足Talbol级配理论的废石胶结充填体进行单轴抗压试验研究,分析了Talbol幂指数、初始孔隙度、胶结材料种类及含量对充填体强度及变形特性的影响规律。结果表明:充填体单轴抗压强度、弹性模量、变形模量均随Talbol指数n呈先增大、后减小的趋势;采用2次多项式拟合充填体单轴抗压强度与骨架颗粒Talbol指数的关系,得到了使充填体强度及变形特性达到最优的Talbol指数n=0.45。充填体单轴抗压强度基本上随其初始孔隙度的增大而减小,但当孔隙分布均匀性较差时,其试验结果具有一定差异。满足Talbol分布的充填体强度随其胶结材料胶结性能的提高而逐渐增大,其中水泥胶结充填体单轴抗压强度可以达到黏土胶结充填体的6倍以上。另外,胶结材料含量的提高同样可以增大充填体的强度,并能够相应地缩短其应力-应变曲线中的孔隙压密阶段。 相似文献
5.
为探究不同充填间隔时间(FTS)和料浆浓度对胶结充填体长期强度影响机制,配制70%、72%、75%三个浓度、充填间隔时间为12、24、36、48 h的两分层胶结充填体试件,开展单轴抗压强度(UCS)试验并探究其力学特性及其破坏形式。试验结果表明,（1）胶结充填体峰值抗压强度随充填间隔时间增大而呈递减趋势,充填间隔时间一定时胶结充填体抗压强度随料浆浓度增大而增大,且峰值抗压强度与充填间隔时间呈多项式函数规律;（2）胶结充填体试件加载过程中表现为压密阶段、线弹性阶段、裂纹扩展阶段和破坏发展4个阶段,随充填间隔时间延长,胶结充填体的破坏形式可能表现为张拉破坏–拉剪破坏过渡–拉剪混合破坏的损伤模式。研究结论能够为后期充填体强度设计和稳定性控制提供有益参考。 相似文献
6.
充填体分层现象在分段或阶段嗣后填充采空区过程中较为常见。设置65%、70%、72%和75% 4个浓度,填充次数为1、2、3和4制作不同分层胶结充填体试件,进行单轴压缩试验探究其力学强度及其破坏模式。试验结果表明：（1）相同浓度条件下,随着填充次数增多,胶结充填体的单轴抗压强度弱化效应越明显,而当浓度在65%～75%之间变化时,对应强度折减系数介于0.592～0.967;（2）充填体单轴抗压强度与填充次数之间满足二次多项式函数关系,而与料浆浓度呈对数函数分布;（3）不同分层胶结充填体的破坏模式主要表现为共轭剪切破坏和贯穿分层面的张拉破坏。低强度夹层可能是导致分层胶结充填体强度降低的原因,能够为后期填充采空区的充填体强度设计提供可靠的理论依据。 相似文献
7.
《岩土力学》2020,(10)
为了揭示金属矿尾废胶结充填体(CWRB)破裂过程中的细观力学特性及尾废胶结协同作用机制,采用单轴压缩实时CT扫描力学试验对废石含量(WBP)为0%(全尾砂胶结充填体)、30%、50%和70%的充填体损伤破裂演化过程进行了可视化和数字化表征,揭示了充填体细观损伤和破裂演化的内在力学机制。结果表明,尾废胶结充填体中的废石含量会影响应力-应变响应,随着废石含量的增加,充填体的强度也会增加。强度增加的主要原因是试样中挠曲破裂面扩展的地质力学效应。充填体开裂后裂纹的形状受废石块形状、大小和分布的影响。基质-块体交接界面为充填体中最薄弱的部分。裂纹的形成和扩展最终导致了尾废胶结充填体的应力剪胀行为。界面损伤开裂控制了试样中裂纹扩展路径及强度特性。尾废胶结充填体的强度效应取决于块石的含量,废石-废砂胶结充填体的相互作用控制着试样强度的增加,块石间的互锁作用对于提高试样的整体刚度具有重要影响。该研究成果对于金属矿固废绿色处置及矿产资源的可持续开发具有理论指导意义。 相似文献
8.
《岩土力学》2021,(3)
利用测温法和核磁共振法测量了不同浓度典型盐溶液（NaCl、Na_(2)CO_(3)）饱和重塑粉土的冻结温度及冻结特征曲线,并与不同浓度的NaCl、Na_(2)CO_(3)纯溶液作对比分析,研究初始含盐量对冻结温度及未冻水含量的影响。结果表明：土样冻结温度随初始含盐量的增加而逐渐降低;相同浓度NaCl溶液饱和土样的冻结温度低于相应纯溶液的冻结温度,但相同浓度（0.6 mol/L）Na_(2)CO_(3)溶液饱和土样的冻结温度却比纯溶液的冻结温度高;同一负温下,土样中未冻水含量随NaCl初始含盐量的增加而增多,但随Na_(2)CO_(3)初始含盐量的变化不明显。通过机理分析,表明盐类型和含盐量对土水势具有不同的影响。基于改进的广义Clapeyron方程,将含盐分土冻结温度表达式引入未冻水含量预测模型,得到了能够考虑不同含盐量影响的土体未冻水含量的定量表达,并与实测数据进行对比,验证了该模型能够较为合理地预测不同温度下含盐土体的未冻水含量。 相似文献
9.
超细全尾砂材料胶凝成岩机理试验 总被引：4，自引：0，他引：4
矿山充填是保护土地资源、生态环境,实现矿山无废开采和消除重大安全隐患的理想途径。以某矿全尾砂为试验材料,在分析该矿全尾砂材料的化学成分、粒径级配组成等基本物理、化学特性基础上,借助XRD能谱分析和电镜扫描（SEM）方法,得到不同条件下的超细全尾砂材料胶凝成岩微观规律。对比以水泥、固结剂1#和固结剂2#分别为胶结剂时充填体的强度结果表明,在灰砂配比、浓度和龄期相同的条件下3种胶结材料充填体的强度大小为：固结剂1#＞固结剂2#＞水泥;固结剂1#可替代水泥作为矿山全尾砂胶结充填的胶结剂,且价格比水泥便宜,有利于降低矿山充填成本。对不同条件下的充填体强度曲线进行拟合,得到充填体的单轴抗压强度增长规律：在养护龄期28 d之内,充填体单轴抗压强度增长规律随龄期变化基本相同,皆遵循指数函数曲线增长规律;当以固结剂1#、2#分别作为胶结材料时,强度增长规律与水泥为胶结剂时相同;强度增长曲线趋势与灰砂配比、料浆浓度以及养护龄期正相关。 相似文献
10.
含水量对冻结含盐粉土单轴抗压强度影响的试验研究 总被引：7，自引：4，他引：3
采用取自甘肃省白银市平川区黄河岸边的天然盐渍土,用蒸馏水洗去土中的盐分,配制成NaCl/Na2SO4含量为1.5%,含水量不同的试样,研究了冻结条件下含水量对冻结含盐粉土单轴抗压强度、破坏应变的影响.结果表明:当含水量较小时,随着含水量的增加,冰的胶结作用增强,并与土颗粒、盐晶体一起承受荷载,冻结含盐土的单轴抗压强度不断增大;当含水量超过某一值时,试样更多地呈现出冰的性质,而冰的强度远远小于矿物颗粒的强度,单轴抗压强度随含水量的增加而减小.随着含水量的变化,含盐土的破坏应变与单轴抗压强度有相似的变化规律. 相似文献
11.
Alireza Ghirian 《Geomechanics and Geoengineering》2016,11(4):237-251
A pressure cell apparatus has been developed in this research work to study the long-term hydro-mechanical behaviour of cemented paste backfill (CPB) cured under applied stress. The samples are cured for 7, 28, 90 and 150 days and the evolution of their mechanical, hydraulic, physical and microstructural properties is studied. Also, the suction, temperature and electrical conductivity are monitored for a period of 150 days of curing. The testing and monitoring programmes are conducted in undrained conditions, with and without pressure application. The obtained results show that the curing stress affects the hydro-mechanical behaviour of CPB for up to 28 days. Within this curing period, the CPB exhibits enhanced hydro-mechanical performance. However, application of sustained excessive curing stress onto the CPB samples induces the propagation of microcracks in the backfill structure, thus causing lower mechanical strength and higher fluid permeability at the more advanced ages. Furthermore, the mineralogical and chemical compositions of the tailings (e.g., sulfidic tailings) can significantly alter the mechanical strength properties (uniaxial compressive strength and elastic modulus) and the permeability of the CPB. The evolution of coupled factors and characteristics of the CPB at an early age control and influence its long-term behaviour and performance. 相似文献
12.
Naguleswaran Niroshan Ling Yin Nagaratnam Sivakugan Ryan Llewellyn Veenstra 《Geotechnical and Geological Engineering》2018,36(4):2171-2187
This paper is an attempt to relate the microstructure to long-term mechanical properties of the cemented paste backfill produced from a hard rock mine tailing from North Queensland in Australia bound with flyash-based geopolymer (geopolymer), flyash-blended cement (FBC), and general purpose cement (GPC). A relatively high slump (260 mm) paste backfill mix with 74 wt% solids has been used to prepare cylindrical paste backfill samples with a diameter of 50 mm and a height of 100 mm. The uniaxial compressive strength tests were conducted on all samples after curing for 112 days to obtain their strength, failure strain and Young’s modulus. Fractured samples were examined under scanning electron microscope to understand the failure mechanisms at the microstructural scale. The results show that binders significantly affected the mechanical properties of paste backfills (ANOVA, p < 0.05). The paste backfill bound with geopolymer gave the lowest strength and Young’s modulus, while the paste backfills bounded with FBC and GPC showed comparable higher strength and modulus values. This was attributed to the relatively well-packed paste backfills with less cracks and smaller pore sizes in these paste backfills bound with FBC and GPC binders. In particular, needle-shaped particles, which were originally identified in GPC, highly influenced the mechanical property of paste backfills. These results indicate that fly ash can be used to partially replace the cement as a binder for paste backfills to achieve economic and environmental benefits. 相似文献
13.
冻结盐渍砂土单轴强度特性研究 总被引：5，自引：3，他引：2
通过对兰州盐渍砂土重塑土添加不同量的盐分来模拟不同含盐量的盐渍土, 并对其进行单轴抗压试验, 分析其在不同含盐量、不同温度及不同速率的应变加载情况下, 冻结盐渍砂土的单轴抗压强度的变化规律, 重点讨论了盐分对土体力学参数的影响以及弹性模量与含盐量、温度的关系. 结果表明: 易溶盐含量的增加会导致单轴抗压强度逐渐降低, 试验温度越低抗压强度会越大; 应变加载速率的增加会增大土体的单轴抗压强度, 同时会缩短土体达到应力峰值的时间; 土体含盐量越大弹性模量越小, 温度越低弹性模量越大. 相似文献
14.
膨胀土是一种特殊的黏土,具有明显的胀缩性和多裂隙性,在寒区渠道工程中极易诱发各种冻害。单轴压缩特性是冻土物理力学特性的重要分支,为研究冻结膨胀土的单轴压缩特性,开展了不同干密度和温度下冻结膨胀土单轴压缩试验。试验结果表明:随着干密度的增加,各温度工况下试样的应力-应变关系曲线均由弱应变软化转为应变硬化形态,且试验温度越高,曲线的软化特征越显著。不同温度工况下试样的破坏模式差异明显。当试验温度为-2℃时,试样破坏时其表面出现明显的局部坍塌与剥落,而-5℃、-10℃和-15℃工况下试样的最终破坏形态均为“鼓状”破坏,试样表面无明显的裂缝和剪切面。冻结膨胀土试样的单轴抗压强度随干密度的增加而线性增大,亦随温度的降低而增大,但在不同的温度区间内增幅不同,其变化幅度主要与试样内部含冰量密切相关。此外,试样的弹性模量随着干密度的增大和温度的降低均线性增大。 相似文献
15.
冻融循环对黏质粗粒土单轴抗压性能影响的试验研究 总被引：2，自引：2，他引：0
循环冻融作用下粗粒土的力学性质对于高寒地区边坡稳定性分析意义重大。以藏区某一排土场土体作为依托,开展了不同冻融循环次数后不同级配黏质粗粒土的单轴压缩试验,研究冻融循环作用对黏质粗粒土单轴抗压性能的影响。结果表明：冻融循环作用对黏质粗粒土应力-应变关系曲线性状及破坏模式有一定的影响,可使其应变呈现由脆性破坏（软化）向塑性流动（硬化）变化的规律。当提高冻融循环次数时,该类土体的弹模和抗压强度均显著减小,其中5~9次冻融循环前减小幅度较大,之后基本保持不变。单轴抗压性能的弱化与土样循环冻融过程中伴随的细颗粒团聚、大中孔隙增多、密实度下降有关。20次冻融循环后,该土质土样抗压强度、弹模最大降低幅度各自高达43%和77%。可见随着提高细砾组的含量,土样的抗压强度和弹模均呈现下降的趋势,这与该土样内粗、细土颗粒的比例及强度发挥机理密切相关。粗粒土单轴抗压破坏应变随冻融循环次数和细砾组含量的增加有一定的增加趋势。 相似文献
16.
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. 相似文献
17.
Like any other coal, the highly heterogeneous nature of brown coal can sometimes make it difficult to interpret the results
of laboratory experiments. More homogeneous samples with properties reproducible in the laboratory would provide significant
advantage, especially in understanding the effects of various factors in the properties of coal. An attempt was made to develop
reconstituted coal (RC) samples in the laboratory through an extensive material development and laboratory testing programme.
The latter consisted of mainly uniaxial compression tests. The main objective in developing the RC material is to use it in
future research on CO2 sequestration in unmineable coal seams. A highly homogeneous coal sample would make it much easier to identify, for example,
the effect of CO2 sorption on the mechanical, flow and transport properties of coal. Uniaxial compression tests were conducted on some brown
coal samples to determine the approximate mechanical properties. The results revealed an average uniaxial compressive strength
of 1.46 MPa, an average elastic modulus of 77.43 MPa and a Poisson’s ratio of 0.16. The measured properties were used as a
reference for the development of RC samples. An extensive laboratory experimental programme was conducted to develop RC samples
with the desirable mechanical properties. Portland cement was used as the cementing agent for the RC. Different variables
such as percentage of cement, water content, compaction load and curing time were taken into account when developing RC samples.
Uniaxial compression tests were carried out to ensure that the RC samples were reasonably homogeneous and the properties were
similar to those of natural coal. Percentages of cement by weight of coal such as 4, 6 and 8% were attempted and a 4% cement
mix with 50% water was considered most suitable for the RC samples. Average compressive strength of 0.8 MPa (28-day strength)
and an average elastic modulus of 34 MPa were achieved for the RC samples. Further efforts at improvement would involve better
matching of the uniaxial compressive strength and elastic modulus of RC samples with the natural coal samples. 相似文献
18.
This paper reviews the design and application of paste backfill in underground hard rock mines used as ground support for
pillars and walls, to help prevent caving and roof falls, and to enhance pillar recovery for improved productivity. Arching
after stope filling reduces vertical stress and increases horizontal stress distribution within the fill mass. It is therefore
important to determine horizontal stress on stope sidewalls using various predictive models in the design of paste backfill.
Required uniaxial compressive strength (UCS) for paste backfill depends on the intended function, such as vertical roof support,
development opening within the backfill, pillar recovery, ground or pillar support, and working platform. UCS design models
for these functions are given. Laboratory and backfill plant scale designs for paste backfill mix design and optimization
are presented, with emphasis on initial tailings density control to prevent under-proportioning of binder content. Once prepared,
paste backfill is transported (or pumped) and placed underground by pipeline reticulation. The governing elements of paste
backfill transport are rheological factors such as shear yield stress, viscosity, and slump height (consistency). Different
models (analytical, semi-empirical, and empirical) are given to predict the rheological factors of paste backfill (shear yield
stress and viscosity). Following backfill placement underground, self-weight consolidation settlement, internal pressure build-up,
the arching effect, shrinkage, stope volume, and wall convergence against backfill affect mechanical integrity.
An erratum to this article can be found at 相似文献
19.
考虑力学参数关联的非均质煤概率模型 总被引：3，自引：0，他引：3
何考虑煤的力学参数之间的关联性是非均质煤储层模拟的关键。通过试验获得了阜新五龙矿某工作面102组煤样的弹性模量、单轴抗压和抗拉强度,定义了弹性模量无量纲因数、单轴抗压强度无量纲因数和抗拉强度无量纲因数及拉弹因数比、压弹因数比5个物理参数,并对试验数据进行统计分析,结果表明,（1）煤的弹性模量、单轴抗压强度和抗拉强度均具有统计分布特征,可以用Weibull分布描述;（2）弹性模量因数、单轴抗压强度因数和抗拉强度因数三者之间存在关联性;（3）拉弹因数比和压弹因数比都符合Weibull分布。以弹性模量为基准,建立了考虑参数关联的非均质煤随机概率模型,开发了相应的虚拟煤体生成程序。研究了2个数值算例,算例1分别按考虑力学参数关联和不考虑力学参数关联两种方法生成煤的力学参数,并与试验数据进行对比,结果表明,前者获得的结果与试验数据更接近;算例2对比了2种方法赋值的平面应变煤样单轴压缩下的宏观应力-应变曲线和煤样破坏过程,结果表明,考虑力学参数关联比不考虑力学参数关联得到的模拟结果更合理,利用文中模型能更好地模拟煤的非均质力学特性。 相似文献
20.
You-Liang Chen Jing Ni Li-Hao Jiang Ming-Liang Liu Peng Wang Rafig Azzam 《Environmental Earth Sciences》2014,71(8):3349-3354
It is important to understand the effect of freeze–thaw cycles on the mechanical properties of rocks. In this paper, the variation of the uniaxial compressive strength, peak strain, elastic modulus and stress–strain curves of granite subjected to freeze–thaw cycles with different heating temperatures were studied experimentally and the relationships were derived. As the number of freeze–thaw cycles increases, the compressive strength and elastic modulus decrease, while the peak strain decreases. In addition, an increased temperature increases the peak strain while decreasing the compressive strength and elastic modulus. An expression for the initial damage for the adopted rock material due to freeze–thaw cycling was proposed based on the Loland model. The current research has established a solid foundation for further experimental studies on the fatigue behavior of granite after freeze–thaw cycling. 相似文献