N6/Q235复合板热轧工艺研究

对N6/Q235镍/钢复合板热轧复合工艺采用A、B、C、D四种试验方案进行了研究.其中方案A、C采用的是正常压下,而方案B、D采用的是大压下.试验结果表明,各种方案的加热、轧制均比较顺利,隔离剂涂层厚度选择合适,掀开复合板,复面经喷砂处理后表面质量良好.探伤贴合率达98%以上,贴合良好.各种热轧压下制度轧制的复合板的复层厚度与原设计相同,均控制在标准要求的尺寸范围内.依据对复合板的金相组织、侧断口组织、界面扩散等分析研究,证明获得了组织性能及贴合率均良好的复合板.经过对复合板力学性能各项指标的检验分析,表明所有指标均达到镍-钢复合板标准(YB/T108-97)要求.     

不同围压下灰岩力学特性及破坏力学模型研究

为了研究围压对灰岩力学特性及破坏力学模型的影响,采用MTS815对完整灰岩岩样进行三轴压缩试验。基于岩样宏观破坏形式,建立张拉剪切破坏模型,构建峰值强度与围压关系表达式;讨论张拉剪切模型与纯剪切模型对岩石剪切强度参数值（粘聚力与内摩擦角）的影响。研究结果表明：岩样弹性模量、抗压强度及残余强度均随围压升高而增大,且残余强度与围压呈非线性相关;当岩样最终破坏时,环向应变与轴向应变比值随围压升高呈负指数降低;一定围压范围内,岩石抗压强度受剪切强度参数和抗拉强度影响;张拉剪切模型确定岩石剪切强度参数值随破裂角增大而增大,与纯剪切模型相比,数值均较小。因此,低围压时,考虑岩石破坏模型具有一定的实际意义。     

双钢板-混凝土剪力墙轴心受压性能试验研究

双钢板-混凝土剪力墙是由钢板和混凝土通过抗剪连接件连接组成的新型竖向组合构件和抗侧力构件,其作为一种新型结构具有结构强度高、抗震性能好、施工方便快捷等特点。但对于这种新型结构,设计应用多以具体工程具体研究的方式进行,缺少专用的规范标准。为研究双钢板-混凝土剪力墙的轴向受力性能,完成了4片双钢板-混凝土剪力墙的轴心受压试验,分析了剪力墙在轴心荷载作用下的受力性能和破坏形态,探讨了不同距厚比和对拉螺栓数量对钢板局部屈曲、破坏形态以及承载能力的影响规律。试验结果表明,距厚比对墙体的局部屈曲、破坏形态有较大的影响,但对刚度和承载力影响并不十分显著。     

Effect of expansive fillings on fracture seepage

Based on an investigation of the damage process of fractures filled with expansion media, samples of filling media col-lected on the spot, were obtained. The physical water properties of fracture fillings were tested by a WZ-2 type Dilatometer. Given our test results of the hydrated properties of fracture fillings and the mechanical parameters of altered rock mass collected from the Daye Iron Mine and comparisons between the expansion stress of fracture fillings and mechanical parameters of altered rock mass, the effects of the mechanical response of fillings on fracture seepage are discussed. The results show that the ratio of filling swell pressure to tensile strength of altered rock specimen varied between 11.79 and 36.77 and the ratio of filling swell pressure to shear strength of these rock specimen ranged from 72.11 to 171.18. Therefore, fillings have an important effect on fracture seepage, and the effect of deformation of the fracture caused by swell pressure of the filling mechanics cannot be ignored either. The multiple hydraulic coupling effects of fillings on the impact of fracture permeability are discussed according to theoretical analyses. It is shown that the effect of expansion of fracture fillings greatly affects the deformation of altered rock masses. Both tensile effect and shear effect produced by fracture fillings greatly increase the permeability of fractures. The plastic and liquefaction effects of frac-ture fillings also improve the permeability of fractures. On the basis of this analysis, a mechanical seepage model of filled fracture is established.     

含圆孔偏轴拉伸板强度分析

本文改进了Whitney的点应力准则,在距孔边一特征长度的圆周上应用Tsai-Wu张量准则.改进后的准则可应用于非对称铺层含孔板,并且除了可以确定含孔板的破坏强度,也可以确定孔边开裂位置,应用这一方法对含圆孔的偏轴板拉伸进行了分析,并与实验作了比较,二者吻合较好.     

Effect of Quenching Parameters on Mechanical Property of Ultra High Strength Steel BR1500HS Based on Response Surface Methodology

Hot stamping of high strength steels is defined as a process in which blank is heated to the temperature of the austenite stabilization region for a definite time and then formed and quenched simultaneously in a mold with cooling channels. During this process, the processing parameters of austenite temperature and soaking time have strong effects on the mechanical properties such as quenching hardness, tensile strength and elongation. Hence, it is necessary to investigate the relationship between the mechanical properties and the two processing parameters. In this paper, the orthogonal experiment with two factors and five levels was applied, and the experimental data based on the orthogonal experiment was acquired. Based on the data, regression models were set up and the results of the analysis of variance （ANOVA） showed that it is reliable to predict the quenching hardness, tensile strength and elongation by the regression models. Besides, the optimal results of each single object were obtained based on response surface methodology （RSM）, and global optimums was gained by employing ideal point method in which the quenching hardness, and tensile strength and elongation were considered simultaneously.     

Optimizing SUS 304 wire drawing process by grey relational analysis utilizing Taguchi method

In the stainless steel 304 (SUS 304) wire drawing process,optimizing the die life and wire tensile strength,which are the larger-the-better quality characteristics (QCH) types,is of main interest.Three control factors,involving reduction ratio,lubricant temperature,and drawing speed,were investigated utilizing L9(34) orthogonal array (OA).The grey relational analysis was conducted for the normalized signal-to-noise (S/N) ratios.The ordinal value of the grey grade was then used to decide optimal factor levels.The anticipated improvements in die life and wire tensile strength were estimated 25.31 h and 22.50 kg/mm2,respectively.To decide the significant factor which had effect on each QCH and predict the average value of each QCH,analysis of variance (ANOVA) was performed for S/N ratio and QCH.Confurmation experiments were then conducted,where a good overlap was noticed between the predicted and confirmation intervals for each QCH.The Hotelling 72 and the sample generalized variance control charts were finally utilized in controlling and monitoring future production.In conclusion,the grey relational analysis utilizing Taguchi method is an effective approach for optimizing the die life and wire tensile strength for SUS wire drawing process.     

剪压区和剪跨比对混凝土板受剪承载力的影响

为探究受拉纵筋屈服的情况下,混凝土板内支座控制截面的相对剪压区高度和板的剪跨比对其受剪承载力的影响,完成了4个混凝土板试件的受剪试验.试件由板、板端伸臂构件、板下柱以及底梁构成,试验借助板端伸臂构件在板端施加力偶,在预估斜裂缝起始位置的外侧施加竖向荷载,在竖向荷载和板端力偶共同作用下使板顶纵筋在斜裂缝与其相交处接近屈服...     

模拟岩石的平行粘结模型微观参数标定

针对平行粘结模型不能同时满足岩石抗拉强度和抗压强度的问题,通过模拟岩石的单轴拉伸试验和单轴压缩试验,以已有的Lac du Bonnet花岗岩的室内试验结果为目标,标定了不同孔隙比和不同不均匀系数岩石离散元试样的微观参数。从微观破坏机制角度指出了平行粘结模型的不足之处,并提出了改进方法。研究结果表明:满足抗拉强度和抗压强度的微观胶结强度参数相差一个数量级;模型仅考虑了胶结的抗拉和抗剪特性,忽略了法向力对胶结强度的影响,导致模型不能正确反映岩石的拉压强度比值;建议采用可模拟颗粒破碎的团粒模型或者基于室内试验提出的胶接模型。     

边坡稳定数值计算中失稳判据和岩土强度屈服准则

通过理论分析和典型算例计算,对边坡稳定数值计算中边坡的失稳判据和失稳模式进行了深入的讨论,旨在使数值计算方法更好地服务于工程实际。边坡失稳破坏的力学分析表明,排除人为主观因素的影响,在严格收敛标准下数值计算不收敛、边坡塑性区贯通和特定监测点位移突变这三类常用判据内在的力学表现是一致的,算例1的分析结果进一步证实了该观点。边坡的失稳模式与岩土体的屈服准则密切相关,为使理论计算符合工程实践,应根据岩土体实际抗拉能力对以M-C为典型代表的基于剪切破坏的强度准则进行抗拉修正。以抗拉修正后的M-C强度准则为基础,进一步提出了拉剪复合破坏的强度折减计算流程,算例2的计算结果表明该计算流程是合理的且计算结果的精度要高于现行的计算方法。     

酸溶液对原状黄土抗拉强度的影响试验研究

黄土受到污染后,土体的组分以及内部结构会发生改变,从而使得土体抗拉强度也随之发生改变。通过人工配置盐酸、硫酸和硝酸的4种不同浓度的污染液,对比蒸馏水和污染后的土样进行直接拉伸破坏试验,探讨酸污染黄土的拉应力-拉应变特征及过程,进一步分析不同酸溶液种类、浓度对土体抗拉强度演化规律的影响。结果表明：随着酸污染液的侵入,黄土的抗拉强度均小于未污染状态;且随着污染液浓度的增大,盐酸和硝酸污染黄土的抗拉强度均呈减小态势,而硫酸污染英黄土的抗拉强度却逐步恢复,拟合后的污染液浓度与抗拉强度呈现出较好的幂函数关系。基于黄土的抗拉强度和抗剪强度,探讨酸污染黄土的联合抗剪强度拟合关系。     

加劲板连接双层钢板混凝土剪力墙抗剪承载能力分析

加劲板连接双层钢板混凝土剪力墙是一种新型结构形式的组合剪力墙。为了研究加劲板连接双层钢板混凝土剪力墙的抗剪性能,采用ABAQUS有限元程序对其进行有限元模拟分析。分析了加劲板间距、跨高比、两侧钢板厚度和内填混凝土板厚度等参数对这种剪力墙抗剪性能的影响。分析结果表明:加劲板连接双层钢板混凝土剪力墙承载力高;跨度和钢板厚度是影响加劲板连接双层钢板混凝土剪力墙的主要因素,随着跨高比、钢板厚度的增大,承载力明显提高;最后基于承载力叠加原理提出加劲板连接双层钢板混凝土剪力墙承载力计算公式。     

公路桥梁中陶粒混凝土梁承载力的研究

目的研究陶粒混凝土梁的正截面受弯承载力和斜截面受剪承载力.方法进行6根陶粒混凝土梁和2根普通混凝土梁的正截面受弯承载力试验,分析陶粒混凝土梁正截面受弯的破坏特征,提出了陶粒混凝土梁正截面受弯承载力的计算方法,并将试验实测值与公式计算值进行了比较.基于陶粒混凝土梁斜截面受剪承载力的试验数据,按照目标可靠指标的要求,提出了陶粒混凝土梁斜截面受剪承载力的计算公式,并对该计算公式进行了可靠度分析.结果正截面受弯承载力的试验实测值与公式计算值的比值是1.064;斜截面受剪承载力计算公式的可靠指标为4.966.结论笔者提出的计算方法和计算公式用来计算公路桥梁中陶粒混凝土梁的承载力是安全可靠的.     

陶粒叠合层叠合板的承载能力研究

不加支撑底板的受力性能及叠合面的抗剪切能力为无支撑叠合板应用的关键因素,为研究槽形底板和陶粒混凝土叠合层叠合板的受力性能及凹槽形叠合面的抗剪切能力,对3块底板和3块叠合板进行了的试验和理论分析,研究了底板和叠合板的抗弯承载力、抗裂性能、弹性恢复特性及叠合面的抗剪切能力。理论分析及试验结果表明：无支撑槽形底板和叠合板的实测抗弯承载力、抗裂性能均高于理论计算值,具有较好的弹性恢复特性;陶粒叠合层减轻了自重,凹槽形底板能够保证施工中不加支撑的要求;凹槽形叠合面比矩形叠合面具有更好的抗剪切性能和较好的抗弯刚度。最后,工程应用表明无支撑叠合板能够满足钢结构工程施工周期短的特点,具有较好的经济指标。     

混杂纤维对高性能混凝土拉压比的影响

为研究低掺量钢-聚丙烯混杂纤维对高性能混凝土拉压比的影响,采用正交试验法设计了18组混杂纤维高性能混凝土试件及1组普通高性能混凝土对比试件,通过标准试验方法进行立方体抗压强度和劈裂抗拉强度试验,试验中考虑的因素主要是钢纤维的特征参数(类型、体积率、长径比)和聚丙烯纤维体积率.分析各因素对高性能混凝土拉压比的影响,结果表明:混杂纤维高性能混凝土具有明显延性破坏特征,而普通高性能混凝土表现为脆性破坏,混杂纤维的掺入使高性能混凝土的拉压比最大提高了26.2%,平均提高了9.9%.在影响高性能混凝土拉压比的四个因素中,钢纤维类型的影响最大,其次是聚丙烯纤维的体积率,影响最小的是钢纤维长径比.高性能混凝土中掺入适量钢-聚丙烯混杂纤维后,拉压比显著提高,韧性得到明显改善.     

Effect of Fiber Volume Fraction on Longitudinal Tensile Properties of SiC_f/Ti-6Al-4V Composites

The longitudinal tensile properties of SiC_f/Ti-6Al-4V composites with different fiber volume fractions were simulated by the Monte Carlo 2-D finite element model. The random distribution of fiber strength was expressed by the two-parameter Weibull function. Meanwhile, contact elements and birth-death elements were used to describe the interfacial sliding process after debonding and fiber breakage(or matrix cracking) respectively, which was realized by subroutine complied in ANSYS-APDL(ANSYS Parametric Design Language). The experimental results show that the yield stress and ultimate tensile strength of SiC_f/Ti-6Al-4V composites increase with increasing fiber volume fraction, while the corresponding strain of them is just on the contrary. In addition, almost the same failure mode is obtained in SiC_f/Ti-6Al-4V composites with various fiber volume fractions when the interfacial shear strength is fixed. Finally, the tensile strength predicted by finite element analysis is compared with that predicted by Global load-sharing model, Local load-sharing model and conventional rule of mixtures, thus drawing the conclusion that Local load-sharing model is very perfect for the prediction of the ultimate tensile strength.     

Slope Stability Analyses of Outang Landslide Based on the Peak and Residual Shear Strength Behavior

Most of the natural and compacted fine-grained soil slopes that are in saturated or unsaturated condition undergo a large deformation prior to reaching failure conditions. Such slopes should be designed taking account of their strain-softening behavior using the residual shear strength(RSS) parameters. In this paper, the slope stability of a recently reactivated Outang landslide near the Three Gorges Dam in China is analyzed based on the RSS parameters of unsaturated soils. In addition, comparisons are provided in the FOS values of slope using both the peak shear strength(PSS) and RSS parameters. Firstly, a series of site investigations of the hydrologic and geologic conditions, ground surface displacements and cracks were described. The PSS and RSS behaviors of the sliding soils derived from a series of direct shear test results performed on saturated and unsaturated soil specimens are summarized.Secondly, a series of slope stability analysis were conducted considering the precipitation and Yangtze River water level variation within a representative period of 7 months, based on the PSS and the RSS properties. In this study, three different scenarios were considered, which include: i) considering only the precipitation with a constant water level; ii) considering only the decrease in water level without rainfall; iii) considering the combination of precipitation and decrease in water level. In each scenario, four steps were included to calculate the values of factor of safety(FOS) at different times. 1) A steady-state seepage analysis was conducted with a constant total head at 525 m on the left boundary and 175 m on the slope surface below the Yangtze River water level. The initial pore water pressures were simulated in the slope under no precipitation and variation of water level. 2) A specific boundary condition was applied on the slope surface to model the precipitation and Yangtze River water level variation. A transient seepage analysis was conducted to calculate pore water pressures at different times based on the initial pore water pressures. 3) The FOS values at different times were calculated by the Morgenstern-Price method taking account of the variation of pore water pressures at different times, using the peak shear strength(PSS) parameters. 4) The last step was repeated replacing PSS parameters with RSS parameters.The RSS parameters were lower than the peak values from laboratory's direct shear test results for the soils in the sliding zones. The reduction in shear strength from peak to residual state under unsaturated soil condition was greater than that for a saturated soil. The FOS decreased almost linearly with time for the scenario in which only the influence of rainfall infiltration was considered. However,the total reduction in the FOS was relatively small. The FOS decreased rapidly at a linear rate with respect to time with a decrease in water level for the scenario in which Yangtze River water level decrease was considered. The FOS reached to a relatively constant value after Yangtze River water level reached the lowest value. The decrease in Yangtze River water level was the dominant factor that contributed to a reduction in the FOS. The FOS was strongly dependent on the development of the phreatic line after the Yangtze River water level reached the lowest value. The FOS calculated by RSS(i.e. FOSR) is less than unity; they were approximately 16%lower in comparison to that calculated by PSS(FOSP). If PSS parameters were used, the slope would still be stable even under the combined influence of precipitation and Yangtze River water level decrease. These results are inconsistent with the field observations. For this reason, the RSS parameters should be taken into account to evaluate reliably the slope stability of the Outang landslide.     

混杂纤维HPC深梁受剪承载力计算方法

采用正交试验法设计钢聚丙烯混杂纤维高性能混凝土（简称 H PC ）深梁试件,通过静力试验研究混杂纤维H PC深梁受剪承载力计算方法。正交试验中考虑的因素主要有钢纤维特征参数（类型、体积率、长径比）、聚丙烯纤维体积率、水平及竖向分布钢筋配筋率等。结果表明：混杂纤维能改变无腹筋H PC深梁的受剪破坏形态;混杂纤维的掺入使得 H PC深梁的剪切初裂强度和抗剪极限强度明显提高,其平均提高幅度分别为45．2％和25．6％。将塑性理论应用于混杂纤维 H PC深梁受剪承载力计算得到了很好的结果,分析表明水平及竖向分布钢筋配筋率的大小对混杂纤维H PC深梁抗剪强度的影响不显著,但水平分布钢筋的作用大于竖向分布钢筋。分析了混杂纤维的增强机理,提出了基于“拉杆拱”模型和劈裂破坏计算模式的混杂纤维 H PC深梁受剪承载力计算式。     

弹塑性简支薄板在压缩和剪切作用下的极限承载能力分析

采用有限元分析方法,实现了对弹塑性薄板极限承载能力的参数化分析,对长宽比为1～4,宽厚比为40～200的四边简支薄板进行了有限元分析,通过对45组不同长宽比不同宽厚比的薄板承载能力分析,给出了薄板单独在均匀压缩和剪切荷载作用下的极限承载应力值以及相应的近似计算公式,并进一步分析了薄板在压缩和剪切荷载作用时,薄板的两种极限承载应力间的关系曲线,给出了响应拟合关系曲线.     

计算独柱墩帽梁承载力的改进撑杆-系杆模型

针对独柱式桥墩帽梁在承载能力极限状态下的设计计算问题,提出改进的撑杆-系杆模型来预测该类结构的极限承载力.以某座独柱式桥墩发生严重开裂的桥墩帽梁为背景,利用ANSYS的有限元弥散裂缝模型对开裂的桥墩进行非线性分析.计算结果说明,对于钢筋混凝土独柱墩帽梁这类剪跨比较小的构件,帽梁的弯剪复合受力十分复杂,基于经典的欧拉伯努利梁理论和铁木辛柯梁理论的设计计算方法不合适.对比数值分析的结果,提出基于节点区域双向拉压破坏的改进撑杆-系杆体系模型.该模型进一步考虑了弯起钢筋、箍筋以及混凝土抗拉强度对斜裂缝开展的限制作用,更能反映独柱墩帽梁在破坏阶段的受力特征.对比独柱墩帽梁常用的剪跨比下各理论的适用性可知,该改进模型结果与有限元模型的计算结果吻合.