新型高强预应力让压锚杆巷道支护性能的数值模拟   总被引：1，自引：0，他引：1  

连传杰  徐卫亚  王亚杰  王志华 《岩土力学》2010,31(7):2329-2335

一种新型的高强高预应力让压锚杆在国内煤矿深埋巷道支护中得到了成功应用,与普通锚杆相比,高强度、高预应力和让压性能是其主要特点。基于高强预应力让压锚杆力学模型,建立了让压锚杆-围岩相互作用体系的有限元数值模型,并对巷道围岩应力分布、位移和锚杆受力性能进行了分析。结果表明,高强预应力让压锚杆系统能够减小锚杆荷载,且可防止大变形和深井巷道支护中锚杆过早地进入屈服,对杆体具有保护作用。  相似文献   

深长变径搅拌桩荷载传递规律的试验研究   总被引：2，自引：0，他引：2  

向玮  刘松玉  经绯  刘志彬 《岩土力学》2010,31(9):2765-2771

采用一种新型的地基处理方式--变径水泥土搅拌桩,处理了浙江省湖州地区深达20多米的深厚软土地基,通过对载荷试验和桩身应力实测资料的分析,研究了深长变径搅拌桩的承载特性和荷载传递机制。研究表明,受到桩身强度的限制,荷载沿桩身传递限定在一定范围内;由于桩径的变化,桩身应力在变截面处出现了应力集中现象;桩身轴力沿深度逐渐衰减,且在变径位置以上桩体衰减速率较下部快;最大侧摩阻力发生在桩顶附近,在变径处附近由于扩大头端承作用而锐减,但变径位置以下一定深度范围内的桩侧摩阻力得到提高;扩大头端承力随桩顶荷载的增加而逐渐变大,但占总荷载的比例不大,桩侧摩阻力仍提供了大部分的承载力,因此变径水泥土搅拌桩属于有支点端承力的摩擦桩。结合3种不同单桩破坏模式,提出了深长变径搅拌桩的单桩极限承载力计算公式,经过试算发现与现场试验结果相差在10%以内,计算结果可靠,可推广应用于实际工程中。  相似文献   

高填方涵洞减载机制与数值分析   总被引：4，自引：1，他引：3  

马强  郑俊杰  张军  赵冬安 《岩土力学》2010,31(Z1):424-429

高填方引起的涵顶土压力集中往往造成涵顶纵向开裂,通过涵洞-填土-地基共同工作机制的研究,分析了涵洞减载的原理。通过数值模拟分析了中松侧实、柔性填料、先填后挖法以及地基处理措施对涵顶的土压力集中系数的影响。结果表明：上述方法和措施可以有效减小涵顶土压力,先填后挖法宜采用竖直边坡,开挖沟槽的宽度宜与涵洞宽度相当;涵洞地基应采用柔性处理措施,并延伸至基底以外一定的范围。研究结果可为高填方涵洞减载措施的选取以及涵洞地基设计提供参考。  相似文献   

某住宅楼倾斜原因及相关规范问题的讨论     

刘滔  朱合华 《岩土力学》2010,31(10):3248-3253

分析了导致其倾斜的主要原因：①设计中对在高压缩湿陷性黄土地基上进行大面积填土认识不足;②忽视了周边环境的影响及工程活动对环境改变所产生的反作用;③勘察时将新近堆积黄土误判为一般风成湿陷性黄土。指出了在这一地区进行工程设计时容易忽视的问题：只盯着可能会发生的湿陷变形而忽视了必然要发生的压缩变形。对相关的两个规范问题进行了讨论：①通过理论分析和试验验证了在室内湿陷试验中采用固定浸水压力的不合理性;②对计算湿陷量公式中系数? 和?0的合理性提出了质疑,并给出了修改建议,有助于澄清对于湿陷系数和计算湿陷量的模糊认识。  相似文献   

沉管隧道基槽爆破施工对既有堤岸稳定性影响的数值仿真分析   总被引：1，自引：0，他引：1  

张玉成  杨光华  姜燕  姚捷  史永胜 《岩土力学》2010,31(Z1):349-356

结合爆破数值模拟中爆破荷载的特点,分析了各种荷载施加方法的特点及爆破震动场模拟的要求,基于圣维南荷载等效原理,提出了爆破荷载的等效施加方法,即将作用在炮孔壁上的爆破荷载等效后,施加在同排炮孔中心线或者面上来模拟爆破荷载的作用。结果表明,等效施加方法在近区存在一定差异,但在中远区吻合得较好。利用该等效荷载施加方法,采用三维实体模型计算分析了某沉管隧道基槽爆破施工对既有堤岸稳定性影响,计算了周围不同位置、不同深度位置处的振动响应,并在此基础上,分析研究了减小爆破振动对既有结构物影响的减振措施,可为类似工程提供借鉴。  相似文献   

列车荷载下轨道系统-层状横观各向同性饱和地基动力响应   总被引：4，自引：0，他引：4  

叶俊能 《岩土力学》2010,31(5):1597-1603

基于Biot波动理论,构建列车荷载-轨道系统-双层状横观各向同性饱和地基模型,将模型分为上覆路轨系统和地层系统。对上覆路轨系统和地层系统处理,并利用双重Fourier变换技术,在变换域中将横观各向同性饱和地基动力响应的求解简化为求解一个6阶控制方程的特征值问题,进而得到了列车荷载作用下双层横观各向同性饱和地基力响应的解析结果。利用离散Fourier逆变换得到数值计算结果,重点分析了上下土层的刚度和泊松比对位移和孔隙水压力和剪切应力响应的影响,结果表明,上、下土层刚度差异对地基动力响应有较大影响,土层各向异性参数中模量的影响较泊松比大。计算结果可为软土路基加固深度的确定提供理论依据。  相似文献   

Spatial redistribution of Ditrupa arietina (soft bottom Mediterranean epifauna) during a moderate swell event     

Katell Guizien  François Charles  David Hurther  Hervé Michallet 《Continental Shelf Research》2010

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Parameterization of near-bed processes under collinear wave and current flows from a two-phase sheet flow model     

Laurent O. Amoudry  Philip L.-F. Liu 《Continental Shelf Research》2010

Sediment transport models require appropriate representation of near-bed processes. We aim here to explore the parameterizations of bed shear stress, bed load transport rate and near-bed sediment erosion rate under the sheet flow regime. To that end, we employ a one-dimensional two-phase sheet flow model which is able to resolve the intrawave boundary layer and sediment dynamics at a length scale on the order of the sediment grain. We have conducted 79 numerical simulations to cover a range of collinear wave and current conditions and sediment diameters in the range 210–460 μm$\mathrm{\mu }\mathrm{m}$. The numerical results confirm that the intrawave bed shear stress leads the free stream velocity, and we assess an explicit expression relating the phase lead to the maximum velocity, wave period and bed roughness. The numerical sheet flow model is also used to provide estimates for the bed load transport rate and to inspect the near-bed sediment erosion. A common bed load transport rate formulation and two typical reference concentration approaches are assessed. A dependence of the bed load transport rate on the sediment grain diameter is observed and parameterized. Finally, the intrawave near-bed vertical sediment flux is further investigated and related to the time derivative of the bed shear stress.  相似文献   

Numerical simulation of tide-induced transport of heterogeneous sediments in the English Channel     

N. Guillou  G. Chapalain 《Continental Shelf Research》2010

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Sediment-charged flash floods on Montserrat: The influence of synchronous tephra fall and varying extent of vegetation damage     

Jan Alexander  Jenni Barclay  Janez Sušnik  Sue C. Loughlin  Richard A. Herd  Amii Darnell  Sian Crosweller 《Journal of Volcanology and Geothermal Research》2010

On 20th May 2006 the Soufrière Hills Volcano on the Caribbean island of Montserrat experienced a large dome collapse and intense rainfall generated flash floods. The floods had very high loads of volcanic debris derived both from this and previous eruptions and can thus be classified as lahars. The floods reached unusually high water levels and caused substantial geomorphic change in the Belham Valley. Detailed rainfall and geomorphological data, coupled with the precise timing of events and yewitness accounts have facilitated an assessment of the relative importance of rainfall volume and intensity, older volcanic debris, pre- and syn-flood tephra fall and the extent of pre-flood vegetation damage for the behavior of this and subsequent sediment-laden floods in this setting. The change in runoff behavior was controlled by preexisting vegetation damage and synchronous tephra fall and this was critically important in controlling the impact of these flash floods. Although rainfall intensity and volume have some control on flood occurrence they are not the critical control on flash flood impact on the geomorphology in the Belham Valley. A significant conclusion of this study is that the extreme nature of the flash floods was not caused by extreme rainfall (as is commonly believed to be the primary cause of flash floods) but rather it was the result of changed runoff behaviour caused by the widespread syn-flood tephra deposition and importantly the widespread vegetation damage by volcanic-associated acid rain in the preceding weeks.  相似文献