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1.
Understanding the shear behaviour of the interface between cemented tailings backfill and retaining wall structures (barricades,
bulkheads) is important for the optimal design of barricades or bulkheads, and for mine operators to balance strength and
safety against cost. However, our understanding of the shear behaviour of the aforementioned interface is limited. This paper
is aimed at investigating the interfacial behaviour and properties of cemented tailings backfill-retaining wall structures,
including stress–strain behaviour, cohesion, friction angle and shear stiffness through direct shear tests. Two different
types of barricade or bulkhead materials (brick and concrete) are used in this study. Interface shear tests are performed
at various curing times of the cemented backfill. Valuable results are obtained with regards to the interface shear behaviour
of backfill-retaining structures. Based on these results, interfacial properties between cemented tailings backfill and barricades
or bulkheads show a significant time-dependent variation. 相似文献
2.
为研究高速公路环境与边坡填筑一体化设计关键技术,在对某高速公路段12 m高加筋边坡进行长期工作特性的现场试验研究基础上,建立考虑格栅黏弹性和土体黏弹塑性流变模型的高速公路加筋边坡数值分析模型,采用增量-初应变迭代法对各种工况进行了分析计算。通过与试验测试数据的对比,验证数值的可靠性,进而进行大量变动参数的数值分析,详细地探讨加筋边坡填筑过程中加筋结构的力学特性。在将试验数据和数值分析结果的对比分析的基础上,得到边坡加筋体内土压力、地基应力和格栅拉力分布规律及其成因,随后与类似加筋直墙和单级加筋路堤的研究结果对比,得到多级加筋陡坡的一般规律及其破坏模式。 相似文献
3.
Unsaturated hydraulic properties of cemented tailings backfill that contains sodium silicate 总被引：2，自引：0，他引：2
Recycling the mine waste (tailings) into cemented tailings backfill has economical and environmental advantages for the mining industry. One of the most recent types of cemented tailings backfill is gelfill (GF), a backfill that contains sodium silicate as chemical additive. GF is typically made of tailings, water, binder and chemical additives (sodium silicate gel). It is a promising mine tailings backfill technology. From a design point of view, the environmental performance or durability of GF structures is considered as a key factor. Due to the fact that GF structures are cementitious tailings, their durability and environmental performance depend on their ability to resist the flow of aggressive elements (water and oxygen). Thus, understanding the unsaturated hydraulic properties of GF is essential for a cost-effective, environmentally friendly and durable design of GF structures. However, there is a lack of information with regards to unsaturated hydraulic properties of GF, the factors that affect them and their evolution with time. Hence, the unsaturated hydraulic properties (water retention curve (WRC) or water characteristic curve, air entry value (AEV), residual water content, unsaturated hydraulic conductivity) of GF are investigated in this paper. GF samples of various compositions and cured in room temperature for different times (3, 7, 28, and 90 days) are considered. Saturated hydraulic conductivity and microstructural tests have been conducted; WRCs are measured by using a WP4-T dewpoint potentiameter and the saline solution method. Unsaturated hydraulic conductivity is predicted using the van Genuchten (1980) equation. The water retention curve (WRC) is determined as the relationship between volumetric water content and suction for each GF mix and curing time. The van Genuchten (1980) equation is used to simulate the WRC to best-fit the experimental data. AEV and residual water content are also computed for each mix and curing time. Furthermore, functions are developed to predict the evolution of AEVs, residual water content and fitting parameters of the van Genuchten model with degree of hydration. Important outcomes have been achieved with regards to unsaturated hydraulic properties. The unsaturated hydraulic conductivity of GF was calculated to decrease when the suction, binder content, and degree of hydration increase. The effects of binder content and degree of hydration are more obvious at low suction ranges. The obtained results would contribute to a better design and assessment of the durability and environmental performance of GF structures. 相似文献
4.
对于超固结黏土和密实砂土等软化材料或非关联塑性材料组成的地基、边坡及挡土墙墙后土体,在其破坏过程中,会产生应变局部化现象,使得控制方程的类型发生改变,从而导致出现数值解不惟一和解的网格相关性等现象。为了克服这些数值困难,基于强间断分析方法,及单元内嵌不连续面的有限元模型,对地基、土坡、墙后土体的渐进破坏过程进行了数值模拟。计算结果表明,单元内嵌不连续面模型可以有效地模拟土工结构失稳破坏过程,并且能够明显地改善采用常规有限元方法所产生的网格尺寸相关性问题。这一方法可作为传统极限平衡法进行稳定分析、承载力分析的有益补充。 相似文献
5.
Static and dynamic active earth pressure 总被引：1，自引：1，他引：0
Summary The dynamic active earth pressure on retaining structures due to seismic loading is commonly obtained by using the modified Coulomb's approach which is known as the Mononobe-Okabe method. This method has generally been used for cohesionless soils only. A general solution for the determination of total (i.e. static and dynamic) active earth force for a c- soil as backfill was developed by Prakash and Saran in 1966 based on the simplifying assumption that adhesion between the wall-soil interface is equal to the cohesion of the soil, that the surface of the backfill is horizontal, and that the effect of the vertical acceleration can be neglected. This note presents an improved method for calculating the static and dynamic active force behind a rigid retaining wall based on its geometry, inclination of the backfill, surcharge, strength parameters of the backfill, and the adhesion between the wall face and the soil. The effects of adhesion, inclination of backfill, and vertical components of seismic loading for a typical retaining wall are discussed. 相似文献
6.
Cemented paste backfill (CPB) is a mixture of dewatered tailings, hydraulic binders and water. In addition to contributing to the stability of mine workplaces, CPB greatly benefits the environment by minimizing surface tailings disposal. Hence, it has become one of the most commonly used ways in mine backfilling around the world. Temperature can significantly affect the mechanical properties of cemented backfill. A source of heat in CPB is produced by binder hydration. Hence, a FLAC based numerical model is developed to predict and analyse the heat developed by hydrating CPB structures. To validate the model, results of the developed model are compared with three case studies (mathematical, laboratory, and field investigations). The validation results show a good agreement between the developed model and these cases. The effects of stope geometry, thermal properties of both rock and CPB, filling rate, binder content and initial boundary conditions are also investigated. 相似文献
7.
There could be some discontinuities in a soil media such as layers, earth structures, cracks, and fissures so that estimation
of stresses and deformations in these types of soil masses are somewhat different from continuous masses. The discontinuities
in a soil mass could be considered as a special link between two blocks. Transmitted swelling pressures affected by the soil
properties of the backfill especially at the interface between the backfill and retaining wall. In order to estimate the transmitted
swelling pressure distribution behind a retaining wall, using with interface element, a new finite element model and a code
(SWELPRES) have been developed. To evaluate the effect of backfill characteristics and interface element from the transmitted
lateral swelling pressures, four cases of thickness of backfills with or without interface elements are investigated. 相似文献
8.
尾矿充填主要包括3种类型：尾矿砂浆充填、尾矿糊状充填（paste fill）和废矿石充填（rock fill）,其中前面两种充填属于水力充填,第3种属于干式充填。3种充填方法在加拿大的矿山都有应用。压缩强度和渗透性是水力充填材料的关键力学特性,直接影响井下充填的效果。一方面,为了使充填材料具有一定的强度,必须在尾矿砂浆（slurry backfill）材料中添加水泥,其用量非常大,水泥在充填成本中占有很大的比例。另一方面,尾矿砂浆水力充填是利用水力旋流器来分级固体颗粒,颗粒较细的部分将通过溢流派到废矿池中,颗粒较粗的部分回收利用作为井下充填的材料使用,有时充填的尾矿数量不够,需要另外购置砂子混合作为充填材料。如何减少水泥的使用量和从水力旋流器底流增加尾矿砂的细颗粒的固体部分产量,以达到节约充填成本的目的,一直是矿山企业所面临的重要课题。为此,专门研究絮凝药剂对尾矿砂浆充填材料的单轴抗压强度的影响。研究结果表明,絮凝药剂能够大幅度地提高尾矿砂浆充填材料的强度,而且絮凝药剂使用量有一个最优值,使强度达到最大。当过量使用絮凝药剂,尾矿砂浆充填材料的强度则有所降低。 相似文献
9.
Improving Short- and Long-term Stability of Underground Gypsum Mine Using Partial and Total Backfill 总被引：1，自引：0，他引：1
Mohamed Marwan Al Heib Christophe Didier Farimeh Masrouri 《Rock Mechanics and Rock Engineering》2010,43(4):447-461
The stability of underground mines represents a key issue for active and abandoned mines. Over the last few years, several collapses of underground mines in France have affected existing buildings and infrastructures. Many factors are generally identified as the cause of failures: pillar ageing, fractures, and pillars’ height to width ratio, etc. Among the treatment techniques available to prevent instability and reduce the deterioration of pillars, backfill is the most frequently used. A research programme, supported by the French Ministry of the Environment, was developed to study the operability of partial and total backfill using waste material in the Livry-Gargan gypsum mine (near Paris, France), where pillar height is 17 m. The paper focuses on: (1) the characterisation of the gypsum and fill material (laboratory and in situ tests), (2) the in situ measurements, involving 5 pillars equipped with 19 pressure cells, since 1999, (3) and numerical modelling of fractured pillars performed in order to improve understanding of the effects of backfill on the stability of room-and-pillar mines. The study clearly shows the operability and the advantages of partial and total backfill for short-term pillar stability. The induced horizontal pressure generated by backfill can reach 200 kPa. The use of numerical modelling also shows the effect of backfill on fractures and that backfill reduces indicatively the shear displacement and the opening of fractures. Numerical modelling helps in identifying the mechanisms of backfill and in a better understanding of the behaviour of backfilled mines. 相似文献
10.
Experimental and analytical investigations on bearing capacity of strip footing in reinforced sand backfills and flexible retaining wall 总被引：2，自引：1，他引：1
This study focuses on the experimental and analytical investigations of small-scale physical model tests. For this purpose, a set of tests were conducted with and without reinforcement on the top of the backfill. The specimens were different in terms of parameters like the number of geotextile layers, the vertical distance between layers and the strip footing distance from the wall. Soil failure in the bearing capacity step and the backfill shear zones was analysed using particle image velocimetry methods. Bearing capacity of the strip footings was studied using analytical procedures. The results indicate that a reinforcing top zone of the flexible retaining structures may be more appropriate than unreinforced case. The ultimate bearing capacity and wall deflection can be significantly improved by increasing the number of reinforcement layers. When the three layers of reinforcement are used, there is an optimum vertical spacing of the layers at which the bearing capacity is the greatest (h/H?=?0.12, d/H?=?0.33 and u?=?B). The study shows that the analytical solution and the results from the experimental models are in good agreement. 相似文献
11.
The paper pertains to the pseudo-static seismic stability analysis of reinforced soil structures. Using limit equilibrium
method and assuming the failure surface to be logarithmic spiral, analysis has been conducted to maintain internal stability
against both tensile and pullout failure of the reinforcements. The external stability of the reinforced earth wall is also
assessed in terms of its sliding, overturning, eccentricity and bearing modes of failure. The influence of the intensity of
the surcharge load placed on the backfill is also considered in the analysis. The obtained results are validated by comparing
the same with those reported in literature. Studies have also been made regarding the influence of backfill soil friction
angle, horizontal and vertical seismic accelerations, surcharge load, the tensile strength of reinforcement, pullout length
of the reinforcement and number of reinforcement layers on the seismic stability against various failure modes as mentioned
earlier. 相似文献
13.
The present work deals with assessment of earthquake-induced displacement of the base restrained retaining walls (RW’s). A detailed and rigorous finite element (FE) investigation has been carried out following the shaking table experiments on a scaled-down RW model. The FE simulations were performed by conducting several nonlinear time history analyses on a two-dimensional (2D) plane strain FE model of a prototype RW. The hardening and softening of backfill have been simulated by calibrating the Mohr Coulomb material model against the triaxial test results. Role of different backfill into the seismic performance of base restrained RW has also been investigated. It was observed that the cohesionless backfill has a slight influence on the earthquake induced displacement of base restrained RW’s. Amplification of horizontal acceleration in backfill has been observed with no direct correlation with the applied earthquake excitation. The understanding and findings based on shaking table experiment and FE simulations have been used for development of an analytical model for estimation of earthquake induced displacement of base restrained RW. The validity of proposed analytical model has also been examined against the shaking table experiment and FE simulation results.
相似文献14.
Jun-wen Zhang Hai-long Wang Shao-jie Chen 《Geotechnical and Geological Engineering》2018,36(1):235-245
2351 working face with paste backfill method of Daizhuang coal mine in eastern China is selected as engineering background, bearing characteristics of backfill body and supporting intensity of hydraulic support during coal pillar mining with paste backfill are researched. Researches show that: Even if the confining pressure is only 1 Mpa, the paste backfill material shows typical plasticity hardening. The overlying strata of working face with paste backfill method include fractured zone, continuous deformation zone, don’t include caved zone. The distribution of vertical stress above the backfill body is not a horizontal line nor presents saddle-shaped, but presents a wave distribution. The stress above backfill body does not appear abrupt change but tends to be increasing at first and stable at last. The mechanical model of roof stability during coal pillar mining with paste backfill is built, and the mechanics related formula of supporting intensity is also concluded. The hydraulic supports used in 2351 working face can control the roof subsidence effectively, but the efficiency of hydraulic supports is lower, which should be optimized properly. 相似文献
15.
对坦墙墙后土体第二破裂面的研究 总被引：3，自引：0，他引：3
基于土的塑性极限分析理论，从挡土墙最小抗倾覆安全系数和挡土墙背上的最大主动土压力两个角度，分别研究了坦墙后土体中第二破裂面的位置，认为在复杂的挡土结构墙背条件下，用最小抗倾覆安全系数来研究挡土墙后土体的破坏机制较为合理。 相似文献
16.
The shear stress–strain behaviour and shear strength parameters of the interface between cemented paste backfill (CPB) and rock are of practical importance in the optimal and safe design of CPB structures. An understanding of the shear behaviour and properties at this interface is also required to develop comprehensive interface models for CPB-rock analyses, interface design methods for the static and dynamic stability analysis of CPB structures, and building high performance CPB structures. In this study, direct shear tests were conducted to investigate the interface shear strength behaviour between CPB and rock. All tests were carried out in a standard direct shear test apparatus for a range of curing ages of 1 to 28 days for the CPB. The procedures of the laboratory tests will be described. Results will be presented for interface shear behaviour, including stress–strain curves, vertical deformation and shear strength parameters. The test results show that the shear strength parameters and behaviour of the CPB-rock interface are time-dependent and significantly influenced by the normal load. 相似文献
17.
地埋管地源热泵是浅层地热能利用的一种主要形式,回填材料的热物性尤其导热系数是影响热泵系统换热效率的关键。以砂和重晶石粉作为研究对象,探究不同重晶石粉掺比(体积分数)以及不同饱和度样品导热系数的变化规律;并基于体视镜、核磁共振分析等宏细观实验,揭示重晶石粉对回填材料导热系数提高的机制;最后,通过数值模拟手段研究该回填材料导热性能对换热效率的影响。研究表明:重晶石粉对回填材料导热系数的影响显著,掺比20%重晶石粉对回填材料导热系数提高的效果最好,最高可使导热系数提高52.09%;水的含量对导热系数影响也很显著,样品饱水后导热系数明显增加,相比干燥样品提高了4~5倍;重晶石粉对回填材料导热系数的提高主要由包裹效应和填隙效应引起,包裹效应为重晶石粉将砂颗粒表面包裹,而填隙效应则是重晶石粉将砂颗粒之间的孔隙填充;数值模拟结果证明重晶石粉提高回填材料导热系数进而提高地源热泵换热效率的可行性。研究成果为地源热泵回填材料的选择提供了参考。 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.
Abtin Jahanbakhshzadeh Michel Aubertin Li Li 《Geotechnical and Geological Engineering》2017,35(3):1151-1167
There are several good reasons for using backfill in underground stopes, including a reduction of mine wastes on the surface and the improvement of ground stability. Backfilling is now commonly used in underground operations worldwide, so practical methods are required to assess the stress state in stopes, on the surrounding rock mass and on support structures. The majority of existing analytical solutions for the stresses have been developed for vertical openings. In practice, stopes often have inclined walls, and this affects the stress state. Recent numerical studies have shown how the stresses distribution in inclined backfilled stopes is influenced by stope geometry and backfill strength. It has also been shown that existing analytical solutions do not capture the essential tendencies regarding these influence factors. In this paper, a new solution is proposed for the vertical and horizontal stresses in backfilled stopes with inclined walls. This solution takes into account the variation of the stresses along the opening height and width, including the difference between the hanging wall and footwall, for various inclination angles of the walls. Key results are presented and validated using recently performed numerical simulations. 相似文献
20.
《工程地质学报》2018,26(5):1351-1359
理论研究是分析力学问题基本手段,应用理论方法分析充填体整体稳定性的前提条件是存在明确的滑移面。前人许多研究成果基于考虑充填体与围岩接触面即为滑移面,但将接触面作为滑移面分析充填体稳定性缺少数据支持。本文结合前人研究成果,并根据金川二矿区地表变形特征,考虑倾斜（直线和曲线）滑移面,进而解析得到充填体内部竖向应力微分表达式;根据二矿区开采分层充填体的实际情况,考虑为简支梁模型,求得分层充填体局部稳定性的理论解析解;运用数值模拟软件分析二矿区充填体底板最大、最小主应力,判断了充填体发生破坏失稳的可能性。结果表明:充填体不会发生整体失稳垮塌,但充填体局部发生变形破坏的可能性还是存在的,对于双中段开采的上部采空区,充填体发生变形破坏的可能位置位于两侧角点,对于双中段开采的下部采空区,变形破坏位置稍有扩大,但也集中在两侧角点附近,应及时采取合理的支护措施,防止发生充填体局部失稳破坏。 相似文献