西宁北山山前崩塌形成机理及防治

北山山前崩塌群是西宁市最典型的地质灾害之一,近年来,发灾数量明显上升,为研究其影响因素及形成机理,提出切实可行的防治措施,积极应对崩塌地质灾害。本文在收集前人资料及研究成果的基础上,通过Google影像和实际调查对研究区地质构造、地形地貌、地层岩性等做了详细研究,深入剖析了崩塌成因、形成机理及变形破坏模式。认为崩塌的形成是多方面作用的结果,古近纪沉积的泥岩石膏岩及砂岩互层岩组是崩塌发育的物质基础,构造运动为崩塌的形成提供了地质条件,风化作用加剧了崩塌的形成;此外,研究区崩塌属高位岩质崩塌,防治难度大,且出露的泥岩石膏岩与砂岩互层岩组属丹霞地貌景观,防治时应在尽量保护的前提下,采用主动和被动防护相结合的方式进行防治。本研究成果对类似碎屑岩崩塌防灾减灾具有指导和借鉴意义。     

基于时间序列模型的青藏铁路路基变形预测

为分析青藏铁路路基高程不规则变形,通过建立高程—时间响应模型,基于Box-Jenkins建模方法,确定时间序列模型阶数,根据AIC准则,选取适合的时间序列模型,最后给出批量预测全部路基测点高程的算法步骤。研究了青藏铁路路基高程随时间变形规律问题。结果表明：以2010年—2018年每月青藏铁路K1425+050处左侧路基高程数据为例,建立了ARMA(2,1,1)模型,并以2019年数据作为验证集,模型通过了模型适应性检验,证明了模型的有效性和准确性;总结了青藏铁路沿线各测点至2023年12月预测值中可能出现重大变形以及测点左右两侧路基高程差值出现较大差值的10个危险点;在测点K1476+600附近,路基两侧出现明显长距离的差异。可见本模型能准确预测青藏铁路路基高程的变化,对于工程养护维修具有一定借鉴意义。     

主应力法及其在圆锥筒挤压变形力计算上的应用

主应力法广泛应用于工程计算中,本文应用主应力法推导了圆锥筒挤压时所需挤压变形力的计算公式,供模具设计和加工设备选用时参考。     

变形监测基准网的稳定分析

变形监测网的点位差异是由于观测误差引起的,还是由位移引起的,必须对其进行区分。本文简要介绍了整体稳定性检验的平均间隙法、单点位移稳定性的间隙分块法、限差法和t检验法,并结合具体的实例进行分析,得出了有益的结论。     

藏式毛石砌体抗压强度对其弹性模量和峰值应变预测

抗压强度、弹模和峰值应变是藏式毛石砌体力学性能的3个重要参数,由于砌块不规则性和砌筑工艺随机性的影响导致该类砌体抗压强度、弹模、峰值应变都较难直接获得。通过毛石砌块和泥浆黏材强度获得毛石砌体抗压强度,以抗压强度预测弹性模量和峰值应变是为了研究此类砌体变形特征和力学特性。采用西藏传统砌筑工艺砌筑8个毛石棱柱体试件,对棱柱体试件进行单轴压缩力学测试,获得毛石砌体抗压强度、弹模、峰值应变、位移-荷载曲线、破坏形态等。结合已有研究成果对该类砌体抗压强度表达式中砌块与泥浆相关影响系数进一步优化,以抗压强度预测其弹性模量、峰值应变。试验结果表明,该类砌体抗压强度、弹模、峰值应变较低且变形呈阶段性变形特征,位移-荷载曲线与其他类型砌体对比存在差异。以区间估计法和线性回归进行弹性模量和峰值应变预测并与其他类别毛石砌体对比发现吻合度较好。该结论可供该类砌体结构修复、加固和毛石砌体单轴压缩性能研究参考。     

Microstructure/texture evolution maps to optimize hot deformation process of near-α titanium alloy

The microstructure/texture evolution(MTE,for short) map and processing map of a new near a titanium alloy Ti65 were constructed in order to investigate the workability and microstructure evolution of hot deformation.The processing map illustrated four domains,two summit domains and two instability domains.The morphologies of the a phase changed from the spheroidization(α+β region) to the deformed and elongated β grains(near the βtransus temperature T_β),and then to the obvious dynamic recrystallization(DRX)(β region) with the temperature rising from 930 ℃ to 1140℃.Deformation in the α+β field mainly generated the texture component with [0001]or [0223] parallel to radial directions(RDs).While deformation in the β phase field formed two types of texture component with [0001] parallel to RDs and [2110] parallel to compression direction.An optimized processing map was summarized by overlaying the macro-instability map on the original processing map,and the instability domain of Ti65 alloy was confirmed in the area with the strain rate higher than 0.01 s~(-1).     

边坡变形预测研究现状与发展趋势

我国自然边坡地质灾害造成的损失仅次于地震;一批国家重点工程项目的开工建设又形成了很多人工高边坡,这些边坡的变形与稳定影响工程安全,因此,开展边坡安全监测具有十分重要的意义。本文从变形破坏机理、变形监测数据处理、变形预测模型等方面就边坡变形预测的现状进行了深入分析,并就边坡变形预测的发展方向进行了探讨。     

Ge,Si的形变势及其应变层异质结的带阶

采用从头赝势能带计算方法研究了（００１）界面应变对Ｇｅ、Ｓｉ能带结构、平均键能和带阶参数的影响．计算了相应的形变势,并利用形变势的研究结果,采用平均键能方法计算了Ｇｅ／Ｓｉ应变层异质结在不同生长厚度ｈ（或平行晶格常数ａ∥）情况下的价带带阶和导带带阶．     

基础设计中减少地基沉降的几种方法

对地基变形造成的危害进行了分析,阐述了地基基础设计中控制地基沉降的重要性及预防措施.在开展工程项目设计工作过程中,设计人员必须要充分重视地基沉降量和地基沉降差问题,正确地识别这两者之间的关系.对于出现超过规定标准值的情况,需要进一步分析产生的原因,保证建筑物在设计上和使用中的安全稳定.尤其是因为基础的不均匀沉降容易引发建筑物倾斜、倒塌等安全问题需要给予高度重视.该文通过对沉降计算的若干问题进行分析,进一步提出了一些减少不均匀沉降及其危害的措施.     

Deformation mechanism of fine structure and its quantitative relationship with quasi-static mechanical properties in near β-type Ti-4.5Mo-5.1Al-1.8Zr-1.1Sn-2.5Cr −2.9Zn alloy

The deformation mechanism of the fine structure composed of primary α phase (α_p) and acicular secondary α phase (α_s) on quasi-static mechanical properties is still not very clear. The main controversy is focused on the role of α_p in the mechanical behavior. In this paper, the microstructure of the heat-treated near β-type Ti-4.5Mo-5.1Al-1.8Zr-1.1Sn-2.5Cr-2.9Zn alloy after tensile tests was observed by transmission electron microscopy (TEM). And the results showed that in the slight deformation region the dislocations were accumulated at the intersection of α_p and β matrix separated by α_s, while only a few dislocations nucleated in β matrix. In the severe deformation region, a large quantity of dislocations in both α_p and β matrix were observed. It can be inferred that α_p deformed firstly and then activated the deformation of β matrix, that is, the thickness of α_p and the inter-particle spacing of α_s played a dominant role in the deformation process. The quantitative relationship between the yield strength and the microstructure parameters is consistent with this inference. By adjusting the solution treatment parameters and the subsequent aging treatment, three fine structures were obtained, and the corresponding mechanical properties were determined. Furthermore, the yield strength can be described by the mathematical model σ_y ​= ​756.4 ​+ ​135.6/h_p^1/2 +32.2/d_s^1/2, where h_p and d_s are the thickness of α_p and the inter-particle spacing of α_s, respectively.