共查询到20条相似文献，搜索用时 15 毫秒
1.
研究目的：分析深埋隧道的塌方机制并推导塌方体形状曲线的解析表达式。创新要点：基于霍克-布朗准则,采用泛函突变理论推导得到了深埋隧道塌方体形状曲线的解析表达式,并据此分析了围岩参数变化对塌方体形状的影响规律。研究方法：通过理论分析建立深埋圆形隧道的解析模型（图1）,采用泛函突变理论推导基于霍克-布朗准则的隧道塌方体形状曲线解析表达式,并研究围岩参数变化对塌方体形状的影响规律（图3和4,表2）。通过与自然拱理论和模型试验结果的对比（图5–7）验证本文解析解的正确性。重要结论：采用泛函突变理论推导了基于霍克-布朗准则的深埋隧道塌方体形状曲线解析表达式。该解析表达式简洁直观,不仅可以预测无支护条件下隧道的塌落体尺寸,还可以估算塌落围岩作用于衬砌上的荷载。 相似文献
2.
浅埋偏压连拱隧道开裂原因及防治措施 总被引：3，自引：0，他引：3
双连拱隧道施工工序复杂，致使围岩应力发生多次重新分布．尤其在浅埋、偏压情况下，如果施工工序不合理，必然导致衬砌裂缝的出现．以铜黄高速公路汤屯段富溪隧道为背景，指出偏压荷载、地下水和不合理的施工工序是裂缝产生的主要原因．根据不同成因，分别采用设置挡土墙、地表排水、注浆加固、先施工浅埋侧等方法进行处理． 相似文献
3.
双连拱隧道施工工序复杂,致使围岩应力发生多次重新分布。尤其在浅埋、偏压情况下,如果施工工序不合理,必然导致衬砌裂缝的出现。以铜黄高速公路汤屯段富溪隧道为背景,指出偏压荷载、地下水和不合理的施工工序是裂缝产生的主要原因。根据不同成因,分别采用设置挡土墙、地表排水、注浆加固、先施工浅埋侧等方法进行处理。 相似文献
4.
The beam element in FLAC3D can be used to simulate the supporting arch in a tunnel. However, this approach has the shortcoming of its constitutive model, and the bearing capacity and surrounding rock supporting effect of the arch model will be significantly exaggerated. To simulate the supporting arch in tunnel engineering well, a new approach is proposed by improving the beam element. The yield criterion of the beam element subjected to compression-bending loads is established based on the now-available bearing capacity formulas of some typical compression-bending sections. In addition, the yield criterion is embedded in the FLAC3D main program by using the FISH language, and the modification of the beam model and the yielding failure simulation of the supporting arch are finally implemented. Compression-bending tests and roadway tunnel arch support example analysis were performed. The results are as follows: (1) the modified model showed the dependence of the bending moment and axial force on the yielding action of the beam element under compression-bending loads; (2) the implementation program is effective and sensitive; (3) the computing deviation caused by the shortcomings of the original beam element model was effectively suppressed, the mechanical behavior and surrounding rock supporting laws exhibited by the arch model were much closer to reality, and the calculation accuracy and design reliability were improved by the new simulation approach. 相似文献
5.
SU Cheng-li WANG Shu-qing 《浙江大学学报(A卷英文版)》2006,7(10):1723-1732
INTRODUCTION In recent years, research on nonlinear model predictive control has attracted significant attention because most practical processes are nonlinear. In industry process control, model predictive controllers based on linear models (LMPC) are often used to control nonlinear systems. When the operating con- ditions undergo significant changes, the performance of LMPC can deteriorate drastically. Under such conditions, predictive control based on nonlinear models (NMPC) shoul… 相似文献
6.
Unified analytical solutions are presented for the predictions of the stresses and displacements around a circular opening based on nonqinear unified failure criterion and the elastic-brittle-plastic softening model. Unified analytical solutions not only involve generally traditional solutions which are based on the Hock-Brown （H-B） failure criterion or the non-linear twin-shear failure criterion, but also involve other new results. The results of the radius of plastic zone, radial displacements and stresses are obviously different using three rock masses when different values of the unified failure criterion parameter or different material behavior models are used. For a given condition, the radius of plastic zone and radial displacements are reduced by increasing the unified failure criterion parameter. The latent potentialities of rock mass result from considering the effect of intermediate principal stress. It is shown that proper choices of the failure criterion and the material behavior model for rock mass are significant in the tunnel design. 相似文献
7.
朱占虎 《河北能源职业技术学院学报》2004,4(3):64-64,71
通过架棚巷道支护结构分析,架棚巷道破坏原因多是由于巷道的侧压力和底鼓引起,造成棚子相对下沉,使巷道变形、断面变小,采取在巷道两墙打锚杆和棚脚穿钢筋混凝土鞋后巷道围岩对侧压力减小了,支架支承能力增强,提高了巷道的稳定性。 相似文献
8.
9.
WANG Zhou-jing QIAN Edward Y. 《浙江大学学报(A卷英文版)》2007,8(4):644-650
A vague-set-based fuzzy multi-objective decision making model is developed for evaluating bidding plans in a bid- ding purchase process. A group of decision-makers (DMs) first independently assess bidding plans according to their experience and preferences, and these assessments may be expressed as linguistic terms, which are then converted to fuzzy numbers. The resulting decision matrices are then transformed to objective membership grade matrices. The lower bound of satisfaction and upper bound of dissatisfaction are used to determine each bidding plan’s supporting, opposing, and neutral objective sets, which together determine the vague value of a bidding plan. Finally, a score function is employed to rank all bidding plans. A new score function based on vague sets is introduced in the model and a novel method is presented for calculating the lower bound of sat- isfaction and upper bound of dissatisfaction. In a vague-set-based fuzzy multi-objective decision making model, different valua- tions for upper and lower bounds of satisfaction usually lead to distinct ranking results. Therefore, it is crucial to effectively contain DMs’ arbitrariness and subjectivity when these values are determined. 相似文献
10.
Tunnel face stability is important for safe tunneling and the protection of the surrounding environment. Upper bound analysis is a widely applied method to investigate tunnel face stability. In this paper, a tunnel face collapse of Guangzhou metro line 3 is presented. Accordingly, seepage is considered in the upper bound solutions for face stability in layered soils. Steady-state seepage is reached in the first 1200 s of each drilling step. In the crossed layer, the seepage flow is horizontal toward the tunnel face, whereas in the cover layer, the seepage vertically percolates into the crossed layer. By considering the seepage forces on the tunnel face and on the soil particles, the upper bound solution for the support pressure needed for face stability in layered soil with seepage is obtained. Under saturated conditions, the support pressure is influenced by the variation of the depth ratio due to the seepage effect. Moreover, the support pressure depends linearly on the groundwater level. This study provides estimations of the support pressure for face stability in tunnel design. 相似文献
11.
何朋立 《洛阳工业高等专科学校学报》2006,16(3):13-15
用有限元强度折减法计算出的安全系数作为评价隧道围岩稳定性的指标,借助于ANSYS程序,使用莫尔-库仑等面积圆屈服准则,计算嵩山隧道的安全系数,通过分析比较确定最优开挖方案;对隧道的开挖支护过程进行数值模拟,分析应力场、位移场、塑性区和支护结构内力变化规律,为隧道工程施工提供理论指导。 相似文献
12.
目前,用强度折减法分析边坡失稳的判据分析都是从边坡破坏的机理出发。本文从边坡破坏机理和有限元自身特点两方面出发,借助ABAQUS有限元软件对两个经典边坡实例进行计算,分析了三种判据的差异性和统一性。最后得出在有限元分析边坡稳定中,塑性区贯通和特征部位的位移发生突变这两种判据具有统一性;有限元计算不收敛与以上两种判据具有差异性;塑性区贯通在边坡破坏机理和有限元计算中存在差异性。 相似文献
13.
Giuseppe Carlo Marano 《浙江大学学报(A卷英文版)》2008,9(1):15-25
Based on a multiobjective approach whose objective function （OF） vector collects stochastic reliability performance and structural cost indices, a structural optimization criterion for mechanical systems subject to random vibrations is presented for supporting engineer＇s design. This criterion differs from the most commonly used conventional optimum design criterion for random vibrating structure, which is based on minimizing displacement or acceleration variance of main structure responses, without considering explicitly required performances against failure. The proposed criterion can properly take into account the design-reliability required performances, and it becomes a more efficient support for structural engineering decision making. The multiobjective optimum （MOO） design of a tuned mass damper （TMD） has been developed in a typical seismic design problem, to control structural vibration induced on a multi-storey building structure excited by nonstationary base acceleration random process A numerical example for a three-storey building is developed and a sensitivity analysis is carried out. The results are shown in a useful manner for TMD design decision support. 相似文献
14.
李文远 《淮南职业技术学院学报》2006,6(3):10-12
煤矿井工开采的深部矿井巷道矿压随延深而逐步加大,巷道破坏现象日益严重,巷道破坏的状况及其破坏程度与巷道所处的位置、巷道所采用的支护方式和支护材料关系密切;根据巷道的断面大小及形状、巷道的用途、巷道的使用年限要求等巷道属性,选择合适的位置以避开应力集中区,选择合理的支护方式及材料以提高支承能力,对深部巷道进行综合优化设计,可以减轻巷道破坏程度,保证巷道正常使用。 相似文献
15.
闻斌 《常熟理工学院学报》2007,21(4):15-19
理论研究和实践结果表明,线性回归模型中最常用的方法——最小二乘法,在一些情况下表现不理想,因此近些年来,统计学家提出了许多替代方法供选择使用。本文通过参数经验Bayes(PEB)方法构造线性回归模型中可估函数的经验Bayes(EB)估计,并分别在均方误差(MSE)准则及均方误差矩阵(MSEM)准则下讨论它相对于最小二乘(LS)估计的优良性。 相似文献
16.
陈世军 《福建工程学院学报》2019,(3):302-306
研究一类含有三次逆幂非线性矩阵方程双对称解数值计算问题。先用牛顿算法迭代计算导出线性矩阵方程双对称解,再用修正共轭梯度算法(MCG算法)求由牛顿算法导出的线性矩阵方程双对称解或最小二乘双对称解。建立牛顿MCG算法求这类矩阵方程双对称解,数值算例表明牛顿-MCG算法是有效的。 相似文献
17.
研究目的：通过三维数值模拟,研究隧道施工过程对双叠隧道的影响。创新要点：使用全三维数值模拟方法研究软土中双叠隧道施工对先挖隧道或地面的影响。研究方法：1.运用FLAC软件创建双叠隧道的三维数值模型（图1）;2.分情况模拟机械化双叠隧道的挖掘过程;3.研究不同情况下的地面沉降,水平地面位移,以及隧道衬砌的法向位移、法向力、纵向力和弯曲力矩等。重要结论：1.新隧道施工对现有的隧道有很大的影响,最大影响出现在先挖上层隧道的情况下;2.一般来说,上层隧道的挖掘会比下层隧道产生更大的地面沉降;3.下层隧道产生的法向力总是比上层隧道大;4.在多数情况下,下层隧道产生的法向位移和弯曲力矩要比上层隧道小。 相似文献
18.
研究非线性不确定奇异摄动系统的鲁棒稳定性问题.基于引入状态变换矩阵以及构造Lyapunov函数得到了非线性不确定奇异摄动系统稳定的上界ε*,并且获得了该类系统渐近稳定的充分条件,最后给出数值例子来说明如何使用所获得的结果. 相似文献
19.
水工有压隧洞的水力计算是一个很复杂的水力学问题，本文结合管流的计算公式，利用算例详细介绍了水工有压隧洞出口压强及水力计算方法。 相似文献
20.
深埋圆形富水隧道应力与位移的弹塑性解 总被引：1，自引：0，他引：1
研究目的：推导获得深埋圆形富水隧道应力场与位移场分布的弹塑性解析解。创新要点：皋于弹性力学厚壁圆筒受均布压力的拉姆解答和Mohr—Coulomb屈服条件,推导了考虑渗流作用和应力释放时含衬砌深埋隧道的弹塑性解,并采用FLAC3D有限差分程序验证了其正确性。研究方法：通过理论分析建立考虑渗流作用和应力释放的含衬砌深埋圆形隧道的解析模型（图1）,然后推导了基于Mohr-Coulomb屈服准则的隧道同岩与衬砌渗流场、位移场和应力场计算的弹塑性解析公式,并通过数值模拟程序（图2）验证了推导公式的正确性。重要结论：基于前人研究皋础,推导获得了深埋富水隧道应力与位移场分布的理论解析解,并通过数值模拟方法验证了其正确性。该解析解一方面可以用于深埋高水头隧道的预设计,如预测隧道周围的水压力、应力场和位移场分布规律,另一方面可用于校核大型复杂数值模型的正确性。 相似文献