土石混合料剪切面分形特征试验研究   总被引：2，自引：0，他引：2  

董云  柴贺军 《岩土力学》2007,28(5):1015-1020

土石混合料因具有良好的工程特性而被广泛应用于道路、堤坝等工程，填筑体受力后往往沿薄弱面发生剪切破￡混合料的抗剪强度成为稳定和变形分析的重要力学指标。由于土石混合料物质组成的复杂性、结构分布的不规律性及采柠困难性，且受检测仪器的限制，确定其强度指标较为困难。应用改进的直剪试验仪进行了不同类别、不同最大粒径土石福料的室内大型直剪试验，在获得强度指标同时，再现剪切面的实际情况，量测剪切面的起伏特征。根据分形几何学原理，切面具有良好的分形特征，应用三角形棱柱表面积覆盖法编程计算了剪切面的分形维数。初步建立了剪切面分形维数与福料杭萌强度之间的关系，用来快速预测土石混合料的强度指标。  相似文献   

修正的莫尔-库仑理论的解析和验证     

石寒 《岩土力学》2007,28(7):1491-1494

根据主应力可分解为静水应力和偏应力,以及它们在应力莫尔圆和变形方面的相关性,推导出修正的莫尔-库仑理论的数学表达式。从理论上解决了库仑理论和莫尔理论存在的许多缺陷,特别是中间主应力对材料抗剪强度的影响。它的四参数准则的计算结果与一些混凝土的试验数据相当吻合。  相似文献   

三峡引水工程秦巴段输水隧洞稳定性分析     

李东林吴树仁  韩金良刘景儒 《地质通报》2007,26(3):321-326

三峡引水工程秦巴段隧洞总长占线路总长的80%。为了分析隧洞施工及运营中可能发生的工程地质问题,在地质调查、地应力测量和岩石力学参数测试的基础上,利用Ansys有限元软件对引水工程北部不同深度、不同截面形态的隧洞围岩的应力重分布情况进行了模拟计算,得到了圆形隧洞、城门形隧洞和马蹄形隧洞围岩的应力分布结果。利用Hoek-Brown强度准则,得到了隧洞围岩的强度/应力比值,进而对不同深度、不同截面形态的隧洞围岩的稳定性进行了分析。初步认为:隧洞埋深小于1000m时,应优先考虑圆形隧洞和马蹄形隧洞;埋深大于1000m时,应优先考虑城门形隧洞。这项研究成果为引水工程深埋隧洞的设计提供了参考依据。  相似文献   

云母石英片岩的三轴蠕变试验研究   总被引：1，自引：0，他引：1  

陈文玲  赵法锁 《工程地质学报》2007,15(4):545-548

在三轴蠕变试验的基础上,通过对径向蠕变和轴向蠕变的比较研究,得出云母石英片岩的蠕变变形和长期强度特点:径向蠕变变形比轴向蠕变变形敏感,以径向蠕变长期强度作为长期强度更合理;围压越大,对径向变形的约束能力越强,径向蠕变长期强度和轴向蠕变长期强度均增加,径向蠕变长期强度与轴向蠕变长期强度的比值减小。同时指出进行径向蠕变研究的意义。  相似文献   

含盐量对水泥土强度影响的室内试验研究   总被引：1，自引：0，他引：1  

储诚富  刘松玉  邓永锋  邵俐 《工程地质学报》2007,15(1):139-143

通过含盐量对非有机质土加固强度影响的试验研究,得到了含盐量对水泥土强度的提高或减小的阈值为3.5%。当盐渍土的含盐量低于这个阈值时,盐渍土的加固强度会因可溶性盐的结晶膨胀作用,提高水泥土的强度;相反当盐渍土的含盐量高于该阈值时,盐渍土的强度会因可溶性盐的过多的结晶膨胀作用,使水泥土的结构遭到破坏,从而使水泥土的强度大大降低。同时分析了可溶性硫酸盐、镁盐和氯盐对水泥土的浸蚀性作用,并从盐类对水泥土强度的影响从机理上进行了阐释,提出了高含盐量对水泥土破坏作用的对策。  相似文献   

A sub-pixel location method for interest points by means of the Harris interest strength     

Qing  Zhu  Bo  Wu  Neng  Wan 《The Photogrammetric Record》2007,22(120):321-335

  相似文献   

A simplified approach for studying the influence of vertical accelerations on seismic response of slopes     

Sam Frydman 《Geomechanics and Geoengineering》2020,15(1):54-63

ABSTRACT

A simplified approach is presented for estimating permanent displacements in slopes as a result of both vertical and horizontal seismic accelerations. A study of 52 earthquake records showed that the time difference between maximum horizontal and vertical accelerations varied between 0 and 10.3 s. The approach is illustrated for an earth dam embankment by analysing the effects of five of the above earthquake records. The approach combines a pseudo-static slope stability analysis for estimation of the critical (or yield) horizontal-vertical acceleration combinations, and a Newmark type displacement analysis. Guidelines are presented for conservative choice of soil strength parameters of saturated clays for use in the stability analysis. While permanent displacements of up to 40 cm were predicted without considering the vertical acceleration component, no additional displacement above 3.5 cm resulted when this component was included. The predicted additional displacement was consistently less than 10%, and in 50% of the analyses, vertical acceleration led to smaller predicted displacements. The simple approach may be applied in analysis for any slope using real earthquake records. Using existing, empirical expressions for permanent displacement, based only on horizontal accelerations, the effect of the vertical accelerations may be conservatively estimated by increasing the displacement by 10%.  相似文献   

Silica fume stabilization of an expansive clay subgrade and the effect of silica fume-stabilised soil cushion on its CBR     

B. R. Phanikumar  Jagapathi Raju m  Ramanjaneya Raju e 《Geomechanics and Geoengineering》2020,15(1):64-77

ABSTRACT

Expansive soil subgrades, which are subjected to dual swell-shrink problem consequent upon absorption and evaporation of water, need to be improved by chemical stabilization or compacted cushion or geosynthetic reinforcement in order that pavements constructed over them are even, stable and safe. This paper presents extensive experimental data on plasticity, free swell index (FSI) and compaction characteristics of a highly swelling expansive clay stabilized with varying silica fume contents. In another series of tests on a laterite soil to be used as a cushion over the expansive clay subgrade, plasticity properties, compaction characteristics and strength characteristics were determined at varied silica fume contents. Further, CBR of the expansive clay subgrade was determined in the laboratory stabilizing it with varied silica fume contents and providing a cushion of 50 mm thickness of silica fume-stabilized lateritic soil. Liquid limit (LL), plasticity index (PI) and free swell index (FSI) of the expansive clay decreased with increasing silica fume contents. The compaction and strength characteristics of both the soils improved with silica fume stabilization. The CBR of the expansive clay provided with silica fume-stabilized cushion improved significantly.  相似文献   

Investigations of the effects of manganese addition to Dry Creek Saltfield brines     

Peri S.J. Coleman 《International Journal of Salt Lake Research》1998,7(1):25-40

Trials conducted at Dry Creek, a solar saltfield north of Adelaide, Australia, indicate that manganese, as manganous sulphate, can increase both the purity and strength of salt crystals grown at an ambient or neutral-slightly acid pH range resulting in a salt suitable for high purity uses. The improved load bearing strength of the crystals indicates that manganous sulphate could also be useful in salt floor maintenance. However, the impact of an apparently slight rise in pH to 8.5 was significant. Crystals produced at the higher pH from the manganese enriched brine were opaque with many tiny, almost colloidal crystals. The salt did not drain well, had low load bearing strength and was notably impure.  相似文献   

冻结粉土动强度的荷载效应及长期极限动强度   总被引：4，自引：1，他引：3  

沈忠言 《冰川冻土》1998,20(1):42-45

荷载效应包括速率效应和疲劳效应两部分．速率效应使冻土的动强度和退荷回弹动弹模随应变速率加快而提高;疲劳效应使冻土的动强度随振频增加而下降,但在低应变速率下却使动强度略有提高．在高应变速率下动强度大于静强度,在低应变速度下动强度小于静强度,其间存在一个临界应变速率．通过动强度－破坏振次关系,可确定长期极限动强度．  相似文献