寒区再生集料水泥稳定碎石路基的力学和温缩性能北大核心CSCD

为解决废旧沥青混合料(RAP)和铁尾矿砂(ITS)固废处理问题,将两者充当砂石料掺加到水泥稳定碎石中,通过无侧限抗压试验、弯拉试验和温缩试验对水泥稳定碎石进行路用性能研究,分析了RAP和ITS掺量对水泥稳定碎石的影响。结果表明:RAP掺量一定时(25%),ITS掺量增加有利于提高水泥稳定碎石的抗压强度和弯拉强度,但会增大材料的温缩应变和温缩系数,降低温缩性能,其中ITS45(ITS掺量为45%)有较好的温缩性能;ITS掺量一定时(60%),RAP掺量增加不利于水泥稳定碎石的抗压强度,但可以提高水泥稳定碎石的弯拉强度,降低温缩应变和温缩系数,其中RAP70(RAP掺量为70%)温缩性能达到最优;与ITS45相比,RAP70有更宽泛的施工温度区间。     

冻融作用下三类纤维加筋固化土的抗压抗拉性能

合成纤维、矿物纤维和植物纤维加筋土,增强了土的强度和抗变形性能。开展冻融作用下的无侧限抗压试验和劈裂抗拉试验,研究聚丙烯纤维、玄武岩纤维和棕榈纤维加筋石灰固化土的抗压和抗拉性能随冻融次数的变化规律。结果表明：未冻融和冻融环境下,聚丙烯纤维加筋固化土、玄武岩纤维加筋固化土和棕榈纤维加筋固化土的最优质量加筋率分别为0.2%、0.2%和0.4%。随冻融次数增加,三类纤维加筋固化土的抗压强度和抗拉强度均呈阶段性下降,纤维加筋固化土的破坏应变均大于石灰固化土。冻融作用下,聚丙烯纤维加筋固化土的抗压强度、抗拉强度和抗变形性能均优于另两类加筋固化土。纤维与土颗粒间的界面作用力和纤维对土的空间约束作用,增强了土的冻融耐久性。对比三类纤维加筋固化土的试验结果,聚丙烯纤维加筋固化土的抗冻融性能最优。     

石灰改良红层无侧限抗压强度试验研究

红层是一种特殊岩土,作为路基材料时,常会导致不均匀沉陷、翻浆冒泥等病害。为改善其力学性质,工程上通常掺入一定剂量的石灰（Ca（OH）₂）进行改良。由于降水-蒸发的周期性变化,运营期间反复干湿循环作用对路基土的工程性质造成较大影响。基于此,结合室内无侧限抗压强度试验,研究了干湿循环作用对不同掺量的石灰改良红层无侧限抗压强度的影响。结果表明：在最佳含水率下,石灰改良红层的无侧限抗压强度随石灰掺量的增加而增大;干湿循环作用对改良红层无侧限抗压强度的影响与石灰掺量有关,石灰掺量较低时,改良红层的抗压强度随干湿循环次数的增加而减小,石灰掺量较高时,改良红层的无侧限抗压强度随干湿循环次数的增加而显著增大;未改良红层塑性较大,试样均为塑性鼓胀破坏,掺入石灰后,红层强度增大,脆性增强,呈脆性剪切破坏,经历干湿循环作用后,石灰改良红层试样呈多缝锥形破坏。     

模糊数学在数字测井解释岩石强度中的应用

目前岩石相对硬度分六个等级,在实际工作中,可不考虑某一岩石的抗压强度的准确性,只需求出它隶属于某一级硬度的可靠程度即可,为此提出模糊模式识别方法解决这类问题:首先确定与岩石抗压强度相关的3个数字测井参数——强度指数、杨氏模量、密度参与计算,然后分配相应权重,构建与硬度级别相对应的6个模糊子集,最后建立判别岩石硬度分级的6个隶属函数作为模糊模式识别岩石硬度等级。判别原则:将任一深度的强度指数、杨氏模量、密度3个数据加权求和,将其值作为判别对象依次代入6个模糊模式得到6个计算值,按照最大隶属原则,确定其相对的硬度级别,该值越接近1,则其隶属于那个硬度级别的程度就越大。     

Lightly cemented sand in tension and compression

Summary Laboratory test results for the stress-strain relationships for lightly cemented sand specimens are presented. The tests were conducted with the specimens under compression and tension without any confining pressure. The cement content was varied from 4% to 8%. Based on the test results, the variations of the stress and strain ratios at failure with cement content are presented for specimens under compression and tension.     

A comparative study of ANN and Neuro-fuzzy for the prediction of dynamic constant of rockmass

Physico-mechanical properties of rocks have great significance in all operational parts in mining activities, from exploration to final dispatch of material. Compressional wave velocity (p-wave velocity) and anisotropic behaviour of rocks are two such properties which help to understand the rock response under varying stress conditions. They also influence the breakage mechanism of rock. There are different methods to determine thep-wave velocity and anisotropyin situ and in the laboratory. These methods are cumbersome and time consuming. Fuzzy set theory, Fuzzy logic and Neural Networks techniques seem very well suited for typical geotechnical problems. In conjunction with statistics and conventional mathematical methods, hybrid methods can be developed that may prove to be a step forward in modeling geotechnical problems. Here, we have developed and compared two different models, Neuro-fuzzy systems (combination of fuzzy and artificial neural network systems) and Artificial neural network systems, for the prediction of compressional wave velocity.     

1982年卢龙MemＳsub6.1地震余震序列震源机制的矩张量反演

用矩张量反演的方法，通过对1982年10月19日河北卢龙MＳ6.1地震的余震序列的震源机制求解，认为卢龙盆地的主压应力轴方位角为N74deg;E，近东西向；而盆地的北边变为N43deg;E；在盆地中心有些部位主压应力轴转为北西方向，与盆地周边的主压应力轴方位几乎垂直. 这说明在卢龙地震中构造的不同部位地壳应力方位很不一致，反映出卢龙地区构造活动的复杂性. 一方面，由于卢龙位处中国大陆东部，受到来自东部的日本海盆地在太平洋板块驱动力作用下的挤压；另一方面，卢龙又夹持在燕山地块与华北板块之间，因而受块体边界的限制也是很明显的.      

大型滑坡滑带土结构强度再生特征及其机理探讨

大型滑坡滑带土强度参数的正确选取，是作好滑坡稳定性评价和抗滑工程设计的重要环节。本文在现场调研和室内试验基础上，揭示了只要具有一定滑体厚度的滑带土，沿滑面具有强度再生现象，尤其在抗剪强度参数中显著存在一定量值的结构强度。讨论了结构强度再生的条件、变化规律及其再生机理，论证了滑带土的残余强度仅仅是一种瞬时效应，为滑坡滑面强度参数的选取与评价提供了重要的理论依据。     

Influence of width/height ratio on post-failure behaviour of coal

Conclusions The post-failure slope immediately after strength failure decreases on the negative side with the increase inw/h ratio. Atw/h equal to around 10 or 11 this slope becomes almost zero and then again the slope increases but on the positive side with further increase inw/h ratio.At loww/h ratios, the post-failure characteristic touches the abscissa ultimately. Forw/h greater than 4 or 6 after an initial fall, the broken mass starts reconsolidation on further loading due to high lateral constraints provided at the centre and the curve starts rising again. Forw/h ratios greater than 10 or 11, there is no loss in the post-failure strength.     

The petrography,structure and mechanical behaviour of coals

Summary The objective of this study is to determine the parameters which influence coal's mechanical behaviour. The two coals examined (HBL, Simon, France and Barro Banco, Brazil) structurally originated from different deposits. The differences are readily explained by the contrasting composition of vitrain, clarain, durain and fusain. Their mechanical behaviour is linked to their petrographical composition. The Lorrainain coal behavioural pattern was evaluated. It is elastobrittle or elastoplastic with progressive failure. Brazilian coal behaves according to a pattern of elastoplastic with progressive failure or perfect elastoplastic.