基于非线性Mohr-Coulomb强度准则下锚索极限抗拔力研究

根据预应力锚索破裂面的形状参数方程、非线性Mohr-Coulomb强度准则和极限平衡原理,推导出一个能够考虑锚索破裂面形状、岩土体种类、抗拉强度以及围岩压力和灌浆压力等因素的预应力锚索极限抗拔承载力计算公式。理论计算结果和算例分析表明了该理论及其求解方法的有效性和可靠性。     

Estimation of compaction grouting pressure in strain softening soils

A new method was proposed to predict the limited compaction grouting pressure for the soft soils. Theoretical basis of the method considered the conical shear failure above the grout bulb. Using the Mohr-Coulomb yield criterion as the initial yield function, the limited compaction grouting pressure was determined, according to the softening elastic-plastic model based on the conventional triaxial compression tests to simulate the strain softening soils. The small strain in the elastic zone and large stain in the plastic zone and the rational yield function for the strain softening phase stage, the analytical solutions to the compaction grouting pressure were presented. The results indicate reasonable agreement and show a good potential of the proposed method for rationally optimizing the design of compaction grouting operations. Foundation item: Project (200550) supported by the Foundation for the Author of National Excellent Doctoral Dissertation of China; Project (09JJ1008) supported by Hunan Provincial Natural Science Foundation of China     

工程管理专业人才培养体系探讨

人才培养是一项系统工程,需要从系统的角度合理设计人才培养的各个环节和要素。文章从培养目标的科学定位、培养内容的合理设计、培养条件的设置、培养管理协调优化,以及人才培养评价机制的建立等方面全方位地构建了工程管理专业人才培养体系,从而促使工程管理专业达到培养高素质工程管理人才的目的。     

考虑水-力耦合时交通隧道非线性解析

将具有衬砌的圆形隧道各影响因素简化为轴对称问题。考虑水-力耦合、外水压力作用及Hoek-Brown强度准则,求得交通隧道弹塑性非线性解析解。利用数值方法研究各参数对考虑水-力耦合非线性解的影响,分析结果表明：考虑水-力耦合时,应力场、位移场和塑性区半径均较不考虑耦合因素时大,因此隧道开挖时应充分考虑水-力耦合作用。实例...     

基于SQP和上限法的非饱和土条形基础极限承载力计算

综合考虑有效内摩擦角、有效黏聚力、基质吸力等非饱和土强度参数以及基底以下基质吸力随埋深增加而变化的工程实际(以水土特征曲线表征),采用多刚性块上限分析法对非饱和土条形基础竖向极限承载力进行研究.假定非饱和土抗剪强度公式是Mohr-Coulomb饱和土抗剪强度公式的延伸,根据线性破坏准则和相关联流动法则,构建一个承受竖向荷载的非饱和土地基承载力二维机动破坏模式.根据外力功率与内部耗能相等原理获得非饱和土地基极限承载力的目标表达式,并把其转化成一个求含有非线性约束的极限承载力上限解最小值计算模型.对建立的计算模型采用序列二次规划法进行优化求解.研究结果表明:非饱和土抗剪强度参数取值对极限承载力量值具有非线性影响;土中基质吸力存在所引起的附加抗剪强度使非饱和土地基承载力较饱和土得到提高;土体内基质吸力分布方式和地下水位高低对条形基础极限承载力影响也较大,地下水位升高导致基质吸力降低,极限承载力减小;非饱和土过渡为饱和土时,同类方法相比本解答是较优上限解.     

基于Hoek-Brown准则下的富水透水隧洞非线性解析

将具有衬砌的圆形隧道各影响因素简化为轴对称问题。以渗透体积力的方式作用在应力场,基于Hoek-Brown强度准则,推导出塑性区应力场和塑性区半径的解析表达式。实例分析表明,随内外水头差的逐渐增大,渗流场和应力重分布对应力场的影响作用将显著增大,且对切向应力的影响程度要比径向应力的大,洞周压应力和塑性半径逐渐减小。随着m的增大,应力和塑性区半径均随之增加,塑性区半径与参数m为非线性递增关系。算例对比分析表明:考虑应力重分布和渗流时其塑性区半径较不考虑二者时大。     

考虑大变形和排水条件时柱孔扩张问题统一解析

将柱孔周围土体中的应力分布分为弹性区和塑性区,在弹性区中采用小变形理论,在塑性区中采用大变形理论和统一强度准则。根据柱孔扩张问题排水条件时的应力平衡方程、应力和应变连续的边界条件,推导出考虑土体剪胀、大变形、排水条件和中主应力等因素的柱孔扩张问题塑性区半径和极限扩孔压力的理论解答,同时也获得了弹塑性区中的应力和应变场分布规律。理论计算结果与现场实测结果较为接近,初步说明该理论具有一定的工程应用价值。对比分析表明:扩孔压力和塑性区半径受土体剪胀的影响要比b值显著。     

Energy dissipation of cavity expansion based on generalized non-linear failure criterion under high stresses

Based on the compression mechanism for analyzing the cavity expansion problem in soil under high stresses, generalized non-linear failure criterion and large strain and energy conservation in plastic region during the cavity expanding were adopted. The energy conservation equation was established and the limited pressure of cavity expansion under high stresses was given based on the energy dissipation analysis method, in which the energy generated from cavity expansion is absorbed by the volume change and shear strain caused in soil. The factors of large strain and dilatation were considered by the proposed method. The analysis shows that the limited pressure is determined by failure criterion, stress state, large deformation characteristic, dilatation and strength of soil. It is shown from the comparison that the results with the proposed method approximate to those of the in-situ method. The cavity expansion pressure first decreases and then increases nonlinearly with both of shear modulus and dilatation increasing.     

Effective depth of dynamic compaction in embankment built with soils and rocks

Effective depth of dynamic compaction was summarized, and the advantages of dynamic compaction technology of effective depth were analyzed elaborately. The formula determining the reinforcement depth was deduced by using dimensional analysis method. The influential factors of hammer weight, hammer area, dry density of filling materials and filling materials types were comprehensively investigated. The formula of effective depth was established based on the definition of the dimensions analysis. Based on exp...     

京沪高铁桩基沉降时间曲线反分析及预测

在京沪高铁项目中,针对深厚软土地层中的桩基工程,使用FLAC^3D建立的桩基模型进行计算。同时,利用桩基静载试验所得的沉降-时间曲线,在考虑土体存在蠕变效应时,结合位移反分析方法,对桩基土体参数和蠕变参数进行反演。在得到反演参数后,对桩基在长期荷载作用下的沉降进行预测。研究表明：①数值反演结果与实测结果比较相符;②使用反演参数对桩基长期荷载作用下的沉降进行预测,得出未注浆桩和注浆桩在长期荷载作用下的前期沉降量大,且基本达到最大沉降量,后期没有出现明显的蠕变效应。因此,建议可不需要通过注浆来对桩基的蠕变效应进行改善,且当在工期较为紧张时,可减少桩基静置时间。