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通过模型实验,以丽水地区的软粘土为实验材料,以单桩为研究对象,研究了静压单桩入土过程中的挤土效应。比较并分析了单桩入土时的土体位移变化规律和土中的应力变化规律。实验结果表明,挤土效应的影响范围与径向距离成反比关系。静压单桩对土体的位移和应力的影响范围分别在0.7和0.45倍桩长左右。实验结果可以给丽水地区的静压桩的施工措施的制定提供参考。 相似文献
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土工合成材料作为新型的软土地基处理技术,在工程领域大量应用。但是土工合成材料的种类和规格很多,材料的性能也有所不同,所以需要建立可计算出各种土工合成材料所受载荷的方法模型。土工合成材料的单桩承载力由材料的抗拉强度和工程性质决定,考虑将土工材料和碎石桩的相互作用作为已知变量,以及碎石桩所承受的上部载荷,就可以推导出土工合成材料所受到的约束拉力与所在土体围压的桩身强度的关系。通过莫尔-库仑理论和布西内斯克理论推导得到了土工合成材料受的约束拉力沿深度的分布,为土工合成材料碎石桩的设计提供计算依据。 相似文献
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为了研究单桩和群桩产生的挤土效应的差异,设计了模型实验加以研究。实验土体采自丽水地区典型场地的粉土。通过锤击沉入3种不同桩径钢制单桩和20mm桩径的群桩,使用土压力计和位移计测量了土中的压力和土表位移。结果表明沉入单桩时,挤土效应随随桩径增加而增加且原始桩径越大,增大桩径后引起的挤土效应的增量越明显,沉入群桩时的挤土效应约为沉入单桩时的2~3倍。该实验结果可对丽水地区的预制桩工程施工提供参考。 相似文献
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A program for stress analysis of adhesive bonded joints within an elastic range was extended to consider the elastic-plastic stress state in an adhesive layer and its progressive failure. The program is based on the one dimensional finite element method. The von Mises yield criterion and the Mohr-Coulomb failure criterion are used in the program. Numerical analysis of a single lap joint subjected to four-point bending load was conducted and its result was compared with the experimental result. Good agreements were obtained between both results except for the final failure load. The present extension has some advantages. The stress singularity in the adhesive layer at the lap end or crack tip can be avoided due to the simple assumption for adhesive strains. Shorter computing time by the present method than by other general two- or three-dimensional finite element model programs should be much emphasized as one of the advantages. 相似文献
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STUDY AND IMPROVEMENT OF RIHANI-DORAISWAMY ESTIMATION METHOD FOR Cp° WITH COMPUTER PROGRAM
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Based on the group contribution method of Rihani and Doraiswamy, a program system has been set up for automatically analyzing structures and computing ideal gas heat capacities. The method was verifled by using evaluated literature data of 479 organic compounds. The assessment of its computing precision and applicability has been made and some new group parameters recommended. 相似文献
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化工管路传统计算方法的改进及其电算程序 总被引:1,自引:0,他引:1
改变和简化传统的化工工艺管理计算方法,得出简便易算的直接计算方法并编制成计算机程序,可以很方便地解决化工工艺管路计算中需要多次试差循环求解的工程计算问题,为化工管路计算带来方便,适用于一般情况下化管路有关工程的计算。 相似文献
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引 言折流式移动床反应器是郭占成等[1] 提出的一种新型反应器 ,作为一种新型干燥方式 ,还没有在实际中得到应用 .针对折流式移动床内冷态气相和固相的流动特性实验和计算机数值模拟已经完成[2 ,3] ,实验结果表明其压力损失显著低于同操作条件下的固定床 ,物料流动仅依靠物料自身重力和气流作用力 ,可以节省额外的动力和降低气固比 .采用多层床又可以提高热效率 ,强化了气固之间的传质、传热和增加了物料的停留时间 .针对单层或多层床的干燥过程进行数学模拟的研究已有很多[4~ 7] ,但其研究结果都无法适合折流式移动床干燥特性分析 .本文… 相似文献
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分级加载电压技术能够有效延长电渗处理的时间,改善地基的处理效果并能有效降低能耗。在利用分级加载电压技术开展电渗试验时,随着土体的排水固结,土体各点的电势会发生明显的变化,这与现有的电渗固结理论假设土体各点电势保持不变有所差异。利用自主设计的电渗试验仪器开展了分级加载电压下的电渗室内试验,分析了电渗过程中土体有效电势变化的规律。基于该规律并结合Esrig固结理论建立了在阳极处不排水、阴极处排水条件下考虑土体有效电势变化的电渗固结理论,得到了分级加载电压条件下考虑土体有效电势变化的超静孔隙水压力和平均固结度的解析表达式。研究表明,在电压分级加载过程中,土体有效电势变化规律表现为随时间先基本保持不变,后呈抛物线状先增后减。通过试验案例验证了考虑土体有效电势变化所求得解析解的合理性,且该数值计算结果相较于Esrig数值计算结果,前者更加接近实测值,该固结方程的建立为后续分级加载电压技术的推广应用提供了理论依据,也为实际工程提供了参考。 相似文献
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Tom B. Bechtel 《加拿大化工杂志》2004,82(6):1319-1325
A generalized parameter optimization method for computing feedback controller parameters is proposed. The method utilizes the downhill simplex method (DSM), a pattern search algorithm, to determine the optimal parameters that minimize an objective function or performance index. The system model, expressed in terms of state‐space equations is integrated with respect to time at each DSM iteration in order to determine the states. A fourth‐order Runge‐Kutta scheme is used for integrating the state equations. A penalty function approach is used for problems with inequality constraints on the state variables or controls. Though relatively inefficient in terms of the number of function evaluations, DSM requires only that the user provide the model equations, and not their derivatives. Additionally, the DSM code is very compact. Thus, a small and straightforward program allows for controller parameter determination for a variety of state‐space and classical PID feedback control design problems. 相似文献
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R.S.H. Mah 《Chemical engineering science》1974,29(7):1629-1638
It is shown how computation to determine steady-state conditions in pipeline networks can be greatly facilitated using sparse computation techniques. Three network algorithms for direction assignment, node-arc ordering and construction of a minimal length cycle set have been devised for this purpose. These algorithms are readily implemented using list processing techniques, thereby making it unnecessary for program users to supply similar, but often non-optimal, information. Using these algorithms, it is possible to obtain substantial reduction in computing time and core storage. Computational accuracy may also be enhanced through reduced number of rounding errors. The reduction of computing time is particularly dramatic and estimates based on operation counts are partially verified by actual computational experience. For a given network the benefit of a single application of these algorithms is multiplied many times with iterations and different parametric values. The development demonstrates substantial advantages of applying graph-theoretic techniques directly to enhance data processing efficiency. 相似文献