顺层路堑边坡锚杆支护稳定性的有限元模拟分析     

龚文惠  刘涛  黄燕宏 《岩土力学》2005,26(Z2):136-140

基于理想弹塑性本构模型和Drucker-Prager准则,运用ANSYS软件和有限元数值模拟技术,建立了顺层岩体边坡的有限元分析模型。结合沪蓉国道主干线宜昌至恩施公路白氏坪-榔坪段顺层路堑高边坡工程实例,对顺层岩体路堑边坡布设锚杆支护前后的应力、变形和稳定性进行了模拟分析。分析比较表明,锚杆支护结构可以减小边坡临界状态下的最大位移、增大最危险接触面的摩擦力和提高边坡的稳定性系数,从而能有效地提高边坡的稳定性以防止顺层滑坡的发生。  相似文献   

基于粘结和摩擦特性的岩石变形与破坏的研究   总被引：7，自引：0，他引：7  

尤明庆 《地质力学学报》2005,11(3):286-292,258

就微观结构而言,矿物颗粒之间或相互粘结或相互分离,Coulomb准则的粘结力和内摩擦力在局部不能同时存在.粘结力是在变形作用下丧失的,材料丧失粘结力之后通过摩擦承载.若承载能力降低,屈服破坏仅在局部断面发生,具有脆性特征;反之将发生分布的屈服破坏,具有延性特征.围压增加可以使裂隙能够承载的摩擦力超过岩石材料的粘结力,那么当轴向应力增加到粘结力时,材料发生剪切屈服产生塑性变形,而摩擦力不会增加到其最大值,裂隙也不发生滑移.利用摩擦的概念可以理解不同岩石的变形、承载和破坏随围压变化的特征.   相似文献   

Effective strength of saturated double porous media with a Drucker–Prager solid phase     

Wanqing Shen  Zheng He  Luc Dormieux  Djimédo Kondo 《国际地质力学数值与分析法杂志》2014,38(3):281-296

This study aims at determining the macroscopic strength of porous materials having a Drucker–Prager solid phase at microscale and two populations of saturated pores with different pressures at both micro and meso scales. To this end, and taking account of the available results by Maghous et al. (2009), we first derive a closed‐form expression of approximate criterion for a dry porous medium whose matrix obeys to a general elliptic criterion. The methodology to formulate this criterion is based on limit analysis of a hollow sphere subjected to a uniform strain rate boundary conditions. The obtained results are then implemented in a two‐step homogenization procedure, which interestingly delivers analytical expression of the macroscopic criterion for dry double porous media whose solid phase at microscale obeys to a Drucker–Prager criterion. After a brief discussion of the results, we propose an extension to double porous saturated media, allowing therefore to quantify the simultaneous effects of the different pore pressures applied on each voids population. The results are discussed in terms of the existence or not of effective stresses. Finally, they are assessed by comparing them to recently available results. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Behavior of sand–rubber particle mixtures: experimental observations and numerical simulations     

Changho Lee  Hosung Shin  Jong‐Sub Lee 《国际地质力学数值与分析法杂志》2014,38(16):1651-1663

A series of laboratory experiments and numerical simulations are conducted to explore the characteristics of mixtures composed of sand and rubber particles of the same median diameter. The mixtures are prepared with different volumetric sand fractions (sf = V_sand/V_total). The experiment focuses on assessing the strain level on the characteristics of the mixture with the volume fraction of each component. Numerical simulations using the discrete element method are performed to obtain insight into the microscale behavior and internal mechanism of the mixtures. The experimental results show that the behavior of the mixtures is dependent on the relative sand and rubber particles composition with variation in the strain levels. The numerical simulation reveals the effect of the soft rubber particle inclusion in the mixture on the micromechanical parameters. In low sand fraction mixtures, a high shear stress along the contact is mobilized, and the stress state is driven to a more anisotropic condition because of the relatively high particle friction angle of the rubber. The rubber particles play different roles with the strain level in the mixture, including increasing the coordination number and controlling plasticity of the mixture in a small strain, preventing buckling of the force chain in an intermediate strain, and leading to contractive behavior in a large strain. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

A relationship between tensile strength and loading stress governing the onset of mode I crack propagation obtained via numerical investigations using a bonded particle model          下载免费PDF全文

Zhenyu Han  Dion Weatherley  Ruslan Puscasu 《国际地质力学数值与分析法杂志》2017,41(18):1979-1991

Numerical models based on the discrete element method are used to study the fracturing process in brittle rock‐like materials under direct and indirect tension. The results demonstrate the capacity of the model to capture the essential characteristics of fracture including the onset of crack propagation, stable and unstable crack growth, arrest and reinitiation of fracturing, and crack branching. Simulations of Brazilian indirect tension tests serve to calibrate the numerical model, relating macroscopic tensile strength of specimens to their micromechanical breakage parameters. A second suite of simulations reveals a linear relationship between the tensile strength of specimens and the loading stress for which mode I tensile crack propagation ensues. Based on these results, a crack initiation criterion for brittle materials is proposed, prescribing the stressing conditions required to induce tensile failure. Such a criterion, if broadly applicable, provides a practical means to rapidly assess the failure potential of brittle materials under tensile loads.  相似文献   

Discussion of “Shear Strength of an Accumulation Soil from Direct Shear Test” by J. Wang,H. Zhang,H. Wen,and Y. Liang     

Di Zhao  Zhen-Feng Qiu 《Marine Georesources & Geotechnology》2016,34(2):194-197

According to the article named “Shear Strength of an Accumulation Soil from Direct Shear Test” by J. Wang, H. Zhang, H. Wen, and Y. Liang, this paper proposes a more reasonable expression to characterize shear strength in the original paper. The angle of shearing resistance is expressed by the combination of initial and incremental angles of shearing resistance, the relative compactions and water content were used to analyze the effects. The initial and incremental angles of shearing resistance are generally increasing with the increment of the relative compaction, increasing then decreases with the increment of the water content. The finial expressions which combined by the series of simulation equation was given to precisely predict the accumulation soil's angle of shearing resistance in relation to the relative compactions and water content.  相似文献   

下击暴流的雷达预警量化指标研究   总被引：1，自引：0，他引：1       下载免费PDF全文

罗辉  张杰  朱克云  郑佳锋  范艺  高细桥 《Acta Meteorologica Sinica》2015,73(5):853-867

下击暴流是一种局地灾害性天气现象,对航空飞行安全有极大危害,也会对地面物体造成严重损害。依据下击暴流发生前母体雷暴(下文简称雷暴)反射率因子核迅速下降的特征,基于雷达体扫数据,定义了判断下击暴流发生、发展的“单位面积等效势能”概念,并结合下击暴流期间雷暴速度场中层辐合的事实,设计得到了下击暴流出流强度公式。结果表明:(1)单位面积等效势能值的变化准确反映了雷暴强中心高度变化。(2)相邻体扫的单位面积等效势能差,反映了雷暴能量的释放量,下击暴流发生前1—2个体扫的单位面积等效势能差达到最大,这反映了下击暴流的爆发;可通过设置单位面积等效势能的释放量为30%,预警下击暴流的发生。(3)单位面积等效势能的释放能够提前6—12 min预警出下击暴流的发生,并通过出流强度公式量化由下击暴流产生的地面大风值。预警风速的误差由雷暴距雷达的距离决定,距离越近风速误差越小,反之亦然。(4)对6次下击暴流预警结果表明,该指标能够准确预警下击暴流的发生,而出流强度受雷暴识别参数的影响较大,远距离误差较大。  相似文献   

太湖与白马湖疏浚淤泥的触变特性研究     

王亮  曹玲珑  李磊  杨黎静  孙田磊  石萍  田海涛 《工程地质学报》2015,23(3):548-553

利用研制的微型十字板剪切仪对重塑后静置一定时间的太湖与白马湖两种疏浚淤泥进行了强度测试,对两种疏浚淤泥的触变特性进行了研究与比较。研究结果表明,两种疏浚淤泥重塑后最初始时间内触变强度的增长最快,随时间增长触变强度的增长变慢,|448d时触变强度随时间的增长趋于稳定。含水率为液限时白马湖疏浚淤泥的触变强度高于太湖疏浚淤泥。触变强度比率与触变强度的变化趋势类似。含水率越小疏浚淤泥触变性越大。含水率为液限时两种疏浚淤泥的触变强度比率与London和Detroit淤泥接近,小于Beauharnois和Shellhave淤泥,大于Horten淤泥。448d时除Beauharnois淤泥外,其他淤泥的触变强度比率均保持相对稳定。根据定义两种疏浚淤泥均为低灵敏性黏土。  相似文献   

基坑抗隆起稳定安全系数的算法对比分析          下载免费PDF全文

李金锁 《探矿工程》2015,42(3):53-55

基坑隆起变形破坏是一种常见的基坑失稳形式。基坑隆起变形量监测存在一定困难,基坑坑底抗隆起稳定性分析主要是计算安全系数。目前基坑抗隆起稳定安全系数计算方法主要有极限平衡、极限分析和强度折减等方法。结合工程算例,采用上述3种算法进行基坑抗隆起稳定安全系数计算,对比分析了各种计算方法的适用性。结果表明,极限平衡传统算法忽略的工程因素较多,计算结果过于保守,通过修正可以提高适用性。极限分析与强度折减的计算结果较为准确,但极限分析的破坏模式和强度折减中基坑稳定临界状态容许隆起量仍需进一步研究。  相似文献   

缓慢复活型滑坡滑带土的蠕变性质与特征强度试验研究   总被引：4，自引：0，他引：4  

蒋秀姿  宝萍 《岩土力学》2015,36(2):495-501

锁儿头滑坡是甘肃省舟曲县城附近、体积约72.85×106 m3的一个巨型老滑坡。20世纪70年代末滑坡开始复活,至今一直处于缓慢活动之中,显示滑坡活动具有典型的蠕动特点。滑带力学特性是控制滑坡活动机制的关键因素之一,为了弄清该滑坡滑带物质的蠕变性质以及控制滑坡活动的强度指标,通过滑带土残余状态下的直剪蠕变试验,研究了滑坡滑带土的蠕变特性,比较了滑带长期强度和残余强度的关系。研究发现,滑带土蠕变特性与应力状态相关,滑带进入加速蠕变的临界剪应力和剪切速率均与正应力线性正相关。该滑坡应力状态指示其已具备进入加速蠕变的条件。残余状态下该滑坡滑带土的长期与残余强度基本等价,前者略大于后者,且增大量值与正应力有负相关关系。  相似文献