我国城市群整合发展的基础与实践   总被引：5，自引：1，他引：4  

王发曾  刘静玉 《地理科学进展》2007,26(5):77-99

目前, 我国许多城市群还没有形成以城市集群为支撑的有整体竞争实力的地域实体, 区 域协调机制还没有从根本上建立起来。为了解决这个严重制约城市群发展的问题, 必须走整合发 展的道路, 整合发展是城市群战略的重大课题。城市群的整合发展要树立正确的科学理念, 充分 吸取国内外相关研究的宝贵启示。整合发展的理论基础分核心理论和基本理论, 前者有竞争优 势、空间相互作用、空间发展和区域协调理论等, 后者有系统、现代经济增长、可持续发展和区域 创新理论等。城市群的存在、城市群的要素和城市群地区的城镇化是整合发展的现实基础, 涉及 城市群存在状态的演进及其广域存在价值, 资源秉赋、整体实力、产业结构、交通通信和核心城 市, 城镇化的综合水平和面临的主要问题等。城市群整合发展的实践包含6 个方面的内容: 城市 竞争力整合、城市体系整合、产业整合、空间整合、城乡生态环境整合和发展的支撑平台整合。  相似文献   

Countermeasures for breakwater foundation subjected to foreshocks and main shock of earthquake loading     

Babloo Chaudhary  Hemanta Hazarika  Siavash Manafi Khajeh Pasha 《Marine Georesources & Geotechnology》2018,36(3):308-322

Coastal protective structures, such as composite breakwaters, are generally vulnerable to earthquake. It was observed that breakwaters damage mainly due to failure of their foundations. However, the seismically induced failure process of breakwater foundation has not been well understood. This study describes failure mechanism of breakwater foundation as well as a newly developed reinforcing model for breakwater foundation that can render resiliency to breakwater against earthquake-related disasters. Steel sheet piles and gabions were used as reinforcing materials for foundation. The experimental program consisted of a series of shaking table tests for conventional and reinforced foundation of breakwater. Numerical analyses were conducted using finite difference method, and it was observed that the numerical models were capable to elucidate the seismic behavior of soil–reinforcement–breakwater system. This paper presents an overview of the results of experimental and numerical studies of the seismic response of breakwater foundation. Overall, the results of these studies show the effectiveness of the reinforced foundation in mitigating the earthquake-induced damage to the breakwater. Moreover, numerical simulation was used for parametric study to determine the effect of different embedment depths of sheet piles on the performance of breakwater foundation subjected to seismic loading.  相似文献   

波浪作用下单桩基础周围海床液化机制研究   总被引：1，自引：1，他引：0  

隋倜倜  张弛  高玉峰  郑金海 《海洋工程》2018,36(4):88-96

建立波浪作用下单桩周围三维海床动力响应模型,考虑自重影响下的海床长时间固结过程。采用已有物理模型试验数据对模型进行验证,证实其具有较好的适用性。模拟波浪作用下单桩周围三维海床液化区域,通过定量分析超孔隙水压力和土体初始有效应力的变化,讨论单桩插入深度对海床液化的影响机制。研究表明,单桩插入深度发生变化时,土体初始有效应力对海床液化的影响要大于超孔隙水压力,且影响程度随着插入深度的增加而逐渐增大。  相似文献   

开孔率对明基床上开孔沉箱波浪反射系数影响的数值研究     

蔡郁  孙大鹏  赵沛泓  吴浩 《海洋工程》2018,36(5):30-37

开孔率是开孔沉箱波浪反射系数的重要影响因素,迄今为止关于开孔沉箱的物模试验研究成果(包括《防波堤设计与施工规范》)中,开孔率μ通常以线性关系反映在开孔沉箱波浪反射系数的计算关系式中,适用范围为0.2~0.4。但当μ0.2或μ0.4时,开孔率μ对波浪反射系数Kr的影响规律尚需进一步的研究探讨。现借助二维数值波浪水槽,在扩大了的开孔率取值范围内,模拟不规则波与可渗明基床上开孔沉箱的相互作用。结果表明:在0.2≤μ≤0.4的范围内,用线性关系描述开孔率μ对波浪反射系数Kr的影响是合适的;在μ0.4时,数模值和物模试验拟合的经验关系式的趋势是一致的;在μ0.2时,开孔沉箱反射系数K_r随开孔率μ的减小而增大,用物模试验拟合的经验关系式及《防波堤设计与施工规范》中计算公式的线性关系来描述开孔率μ对反射系数K_r的影响是不恰当的。研究成果对开孔沉箱消浪机理的深入认识和开孔沉箱结构的优化设计具有重要意义。  相似文献   

山西数字地震台网单台测定近震震级偏差研究   总被引：1，自引：0，他引：1  

董春丽  梁向军  陈冬焱 《地震地磁观测与研究》2007,28(2):41-46

选用2003年1月～2005年3月山西数字地震台网报告中可交的地震,选取了单台样本数接近和超出100的17个子台数据,从震级偏差频次分布、仪器、量规函数、台基诸因素,对单台震级的影响上作了定量统计和分析,得出仪器影响存在一定的震级负偏差,但不大;量规函数、台基是引起山西台网单台震级偏差的主要原因.本文给出了量规函数和台基校正值,校正之后,单台震级偏差94%(即17个台中除镇川1个)以上震级平均偏差在±0.2之内.这对于提高山西数字地震台网测定近震震级,提高台网速报质量具有极其重要的实际意义.  相似文献   

摄动理论在腐蚀管线随机地震反应分析中的应用   总被引：1，自引：1，他引：0  

刘威  李杰 《地震工程与工程振动》2007,27(2):32-38

埋地管线的腐蚀情况十分复杂,具有随机性的特点,从而导致其在地震激励下的反应必然具有随机性。本文在管线腐蚀离散状态模型和弹性地基梁原理的基础上,利用随机摄动理论推导给出了腐蚀管线在地震激励下位移和应力的解析表达式,并进行了均值和标准差的计算。实例分析中将该方法计算结果与Monte Carlo模拟方法计算结果进行了对比。结果表明,利用随机摄动方法可以快速、精确地求得腐蚀管线的随机地震反应。  相似文献   

打桩振动对周围环境的影响     

黄同林 《福建地质》2007,26(1):52-56

在城市建筑物密集区进行振动沉管施工,引起震动对周围环境的影响已成为地基处理施工中一个突出的问题,通过对某项工程水泥粉煤灰碎石柱(CFG)桩施工振动对周边建筑物影响的测试和分析,对地基处理方法的选型及如何有效减轻和控制施工振动对周围环境的影响,均具有一定意义。  相似文献   

A note on the consolidation settlement of a rigid circular foundation on a poroelastic halfspace          下载免费PDF全文

Jueun Kim  A.P.S. Selvadurai 《国际地质力学数值与分析法杂志》2016,40(14):2003-2016

This paper uses Biot's poroelasticity approach to examine the consolidation behaviour of a rigid foundation with a frictionless base in contact with a poroelastic halfspace. The mathematical development of the mixed boundary value problem involves a set of dual integral equations in the Laplace transform domain which cannot be conveniently solved by employing conventional procedures. In this paper, a numerical solution is developed using a scheme where the contact normal stress is approximated by a discretized equivalent. The influence of limiting drainage boundary conditions at the entire surface of the halfspace on the degree of consolidation of the rigid circular foundation is investigated. The results obtained in this study are compared with the corresponding results given in the literature. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Analytical solutions for Euler–Bernoulli beam on visco‐elastic foundation subjected to moving load     

Dipanjan Basu  N. S. V. Kameswara Rao 《国际地质力学数值与分析法杂志》2013,37(8):945-960

Analytical solutions for the steady‐state response of an infinite beam resting on a visco‐elastic foundation and subjected to a concentrated load moving with a constant velocity are developed in this paper. The beam responses investigated are deflection, bending moment, shear force and contact pressure. The mechanical resistance of the foundation is modeled using two parameters k_s and t_s — k_s accounts for soil resistance due to compressive strains in the soil and t_s accounts for the resistance due to shear strains. Since this model represents the ground behavior more accurately than the Winkler spring model, the developed solutions produce beam responses that are closer to reality than those obtained using the existing solutions for Winkler model. The dynamic beam responses depend on the damping present in the system and on the velocity of the moving load. Based on the study, dynamic amplification curves are developed for beam deflection. Such amplification curves for deflection, bending moment, shear force and contact pressure can be developed for any beam‐foundation system and can be used in design. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

季冻区桥梁基桩抗冻拔验算几个问题的探讨     

盛洪飞 《冰川冻土》1989,11(1):44-52

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