水载压力对管道超声导波信号的影响研究

为了研究水载压力对管道超声导波信号的影响,利用半解析有限元的方法分析了管道导波的频散曲线和波结构,选择L(0,2)模态导波用于实验验证。设计了一个可承受30 MPa压力的防水卡箍,对管道上的压电传感器进行封装。将安装了防水耐压卡箍的管道放入压力舱中进行打压循环测试,压力在0~30 MPa之间变化。打压过程中采集无损伤及5%损伤的管道超声导波信号,分析水载压力对导波信号的影响。实验结果表明,该防水卡箍具有良好的防水和耐压性能,水载压力对L(0,2)模态导波信号幅值没有显著影响。

水载预压下复合地基沉降及桩土受力特性分析

以广东省某高速公路T3标段为研究对象,部分路段采用预制管桩复合地基加固软土地基,采用水袋加载的方法进行等载预压,选取3个典型监测断面埋设传感器,监测分析地基土和桩身的沉降、土压力、桩身轴力的变化规律。结果表明:复合地基中桩体为主要的受荷体,设置褥垫层使其产生刺入变形,可有效调动地基土的承载力;荷载在地基中的传递存在滞后性,提升加载速率可有效改善荷载的传递速率,分级加载有助于达到更好的预压效果;过大的加载速率会导致土压力与桩身轴力出现波动,通过荷载重分配实现桩土共同承担上部荷载。采用水载预压联合预制桩复合地基处理软土路基,可降低30%的施工成本,且可有效提升地基工后的稳定性。

水载预压在沿海地区软土路基施工中的应用

我国沿海地区广泛分布着深厚的软土地基,软土具有强度低、含水量大、渗透性差、压缩性高等特点,因此软土路基的地基高效处理能够直接提升公路质量和加速工期。现阶段,软土地区路基处理常采用素土堆载预压的方式,而在堆载预压中采用更为高效且绿色环保的水载预压已成为一种新趋势。文中依托320国道桐乡凤鸣至大麻段改建工程施工主线K9+228.5~K12+300区间段,根据土层情况对水囊进行合理布置,精准预压。区间内共设84个沉降观测点,监测结果表明该区段的实测沉降量在19.45~88.13mm之间,并通过与素土堆载预压进行直接对比,认为水载预压效果更佳,不仅节约了施工成本,而且还缩短了工期,对类似工程施工具有重要的参考价值。

真空-水载联合预压法处理软土地基的应用技术

在真空-堆载联合预压处理软土地基的施工过程中,密封膜极易破坏,且修复困难。采用地下水代替土方堆载可避免相关难题,并解决土方堆载的雨季施工难题。结合实际工程,从地表沉降、土壤孔隙水压力消散、预压前后土体主要物理力学性质变化等方面,详细论述了其对临海淤泥地质有较好的处理效果。

真空加水载联合加固处理温州港七里港区堆场软基

温州港七里港区后方堆场软基采用真空加水载联合加固处理。选用水载可解决地区缺少土源问题,水载可使膜面荷载均匀、土体均匀固结,对减小建筑物地基工后差异沉降有利;工程加固区各项测试成果表明:通过3个月左右的加固处理,地基平均固结度达到87.4%,说明地基主固结已经完成;在整个加固处理深度范围内,土质指标都有了较大的改善,地基抗剪强度增长50%左右,加固效果显著。类似工程可以借鉴。

水载预压施工技术在软土路基施工中的应用研究

传统土载预压为软土路基施工常见方案,也是高速公路路基施工环节关键技术之一,该施工环节存在弃土处置、工料二次转运、生态破坏等问题。基于此,对软土路基施工中水载预压技术进行研究。从水载预压原理、工艺流程、施工技术要点等方面进行分析。最后结合工程实例对相关软土路基施工中水载预压技术应用效果及经济效益进行分析。经实践证明,该工艺在加速地基土凝固、提高预压沉降效果等方面与传统土载预压方案相差无几,但可显著提升环保效果、降低施工成本,可在同类工程推广应用。

水载预压在软土路基处理中的应用浅析

现阶段,软土地区地基处理主要采用土石方堆载预压的方法,但是受土石方短缺的影响,软土地区路堤堆载预压成本不断上升。在水资源丰富的沿海平原地区,水载预压是一种成本低、工期短、环保效应好的处理方法。基于水载预压在国内的应用现状,总结了该方法的施工要点、优缺点及发展趋势,为相关工程提供参考。

水载预压在高速公路软土路基施工中的应用

软土路基施工是高速公路路基施工质量控制的重点和难点。传统土载预压方案需大规模取土,不仅会对生态环境造成严重破坏,同时也存在后期二次转运和弃土处治等问题。从生态保护和资源节约的角度出发,本文通过水载预压在南益高速公路软土路基施工中的应用,详细阐述了水载预压沉降变形观测技术要求及效益分析等。实践证明:水载预压不仅能和传统土载预压起到同等的预压沉降、加速地基土凝固效果,且可节约工程成本达50%以上。

水载预压在公路软基处理中的应用分析

从水载预压处理的现状出发,结合佛山一环北滘至乐从公路试验段水载试验的实践,分析水载预压的优点,再从安全上、处理效果及经济方面对水载预压进行综合评价。

水载预压法研究与应用

结合广东地区特别是珠江三角洲地区水网密布,水资源分布丰富的特点,以佛山北滘—乐从公路主干线工程为例,对水载预压法进行了试验研究,详细介绍了施工工艺及注意事项,通过耐久性和应用效果分析,指出该工艺合理有效,值得推广。

高速公路软土路基水载预压施工问题探讨

在概述水载预压技术原理的基础上,以某一级干线公路兼城市快速路工程为例,进行了其软土路基水载原因施工技术要点的分析与探讨,应用结果表明,水载预压能取得与堆载预压相同的加固效果,且在节省施工成本、简化施工过程、避免环境污染、不涉及堆载预压方式下土方填筑、借方、弃土二次转运、占用土地资源等方面具有显著优势,适宜在地表水资源丰富的地区推广应用。

水载预压法进行软基处理及其试验分析

针对珠江三角洲地区土 (砂 )源较为缺乏、堆载预压成本较高的情况 ,提出了采用经济性更强的水载预压法进行软基加固 ,并通过试验验证了该方法安全、可靠、有效 ,具有广泛的推广价值。

氡变化的水(气)载衰变机理

本文根据氡在岩、水、气中分布特征和地震前后在某些活动断层上,地下水(气)的向外释放,提出了水氡、气氡的水(气)载衰变机理。指出水氡、气氡与地下水(气)的流速、岩—水中氡的不均匀分布有关,并从而使它成为映震比较灵敏的组分。在水、气两相流情况下,水氡、气氡浓度还与氡在水、气中的分配有关。同时观测水氡和气氡,可以获得更多的地壳应力应变及其伴生效应的信息。

Viscoelasto-plastic properties of deep hard rocks under water environment

Using a circular incremental step load and unload method, a set of rheological experiments were performed to study the viscoelasto-plastic properties of amphibolite in Jinchuan No.2 diggings under different environments. Based on the scientific analysis on rheological experimental data, the viscoelasto-plastic properties of amphibolite under different environments were studied. The results show that the instantaneous elastic modulus and viscoplastic properties of amphibolite are affected little, the viscoelastic properties of amphibolite are significantly affected. Based on the experimental results and characteristics of recovered rock specimen, a generalized Kelvin model was chosen to simulate rheological properties of amphibolites and key parameters were obtained. It is found that the creep deformation modulus E1 is significantly influenced by the water, while the instant elastic modulus E2 is not significantly affected. The discreteness of the viscosity coefficient η is large, the influence of water on η is not clear and needs to be further studied.

Simplified stiffness-based approach for seismic performance evaluation of moment-resisting frame

Based on the concept of stiffness degradation, a damage index of the whole frame and the storey is proposed for the frame seismic performance evaluation. The index is compatible with the non-linear static analysis （e. g. the pushover analysis）, and the structural damage is considered via plastic hinges. Simultaneously, a practical approach is developed to obtain the relationships between the proposed index and earthquake intensities based on the capacity spectrum method. The proposed index is then illustrated through two low-rise reinforced concrete frames, and it is also compared with some other indices. The results indicate that the proposed index is on the safe side and not sensitive to the lateral load pattern. The storey index is helpful to reflect the storey damage and to uncover the position of the weak storey. Finally, the relationship between performance levels and damage index values is also proposed through statistical analysis for the performance-based seismic evaluation.

Relation between Economic Development Level and Resource and Environment Carrying Capacity of Central Area of Yunnan Province Based on Decoupling Analysis

Based on the decoupiing theory and method, an indicator system was built for the relation between economic development level and resource and environment carrying capacity. And the study was carried out on decoupling degree and temporal changes of economic development level and resource and environment carrying ca- pacity in the central area of Yunnan Province. Results indicated that （i） the economic development level and resource and environment carrying capacity in the central area of Yunnan Province mainly experienced strong decoupling, weak decoupling, and ex- pansive negative coupling, and in general it was strong decoupling, and it took on re- verse ＂N＂ in temporal changes. （ii） Change rate of economic development level in the central area of Yunnan Province was greater than zero, but the amplitude of change was not large, while the change rate of resource and environment carrying capacity was negative in 2007-2008, and it was positive in the rest years; from 2007, it took on gradual expansion trend, and scissors difference gradually increased after experi- encing reverse ＂V＂ change. （iii） The strong decoupling was the main situation and it reached the peak value in T5 period and T6 pedod.

ON THE HYDRAULIC FAILURE PROBABILITY OF FLOOD CONTROL DAMS

In flood control dams it is not only the failure to prevent flood larger than their design carrying capacity, but also the uncertainties of hydraulic factors that cause disasters. In general, the hydraulic risk is not considered in most of the hydrological analysis in floodproofing plan and design. In this paper, a method of evaluating the hydraulic risk is developed by employing risk theory, and the concept can easily be extended to other types of risk analysis. As a result, it is possible not to consider the hydraulic resks when the design hydrologic risk of flood control dam is lger. Otherwise, the hydraulic risks must be noticed. The research is very helpful for the development of the flood control theory used at present.

Evaluation Model of Carrying Capacity of Water Resources Based on Standardized Indices of Radial Basis Function

[Objective] The aim was to study on RBF model about evaluation on carrying capacity of water resources based on standardized indices. [Method] The indices were transformed and the averages of standard values in different levels were taken as the standardized values of components of central vectors for basic functions of RBF hidden nodes. Hence, the basic functions are suitable for most indices, simplifying expression and calculation of basic functions. [Result] RBF models concluded through Monkey-king Genetic Algorithm with weights optimization are used in evaluation on water carrying capacity in three districts in Changwu County in Shaanxi Province, which were in consistent with that through fuzzy evaluation. [Conclusion] RBF, simple and practical, is universal and popular.

Evaluation of Environmental Carrying Capacity of Water Resources in Jiangxi Province

In order to quantitatively evaluate the sustainable development status of water resources in Jiangxi Province, the dynamic changes in ecological footprint, carrying capacity and load index of water resources in Jiangxi Province during 2009-2013 were analyzed according to the primary principle and calculation model of ecological footprint. The results showed that in Jiangxi Province during 2009- 2013, the water resources ecological footprint per capita was relatively low; the wa- ter resources utilization level was relatively low; the overall development potential of water resources was great; the water resources ecological carrying capacity per capita and ecological footprint per capita were trended to be increased overall. The changes in water resources ecological footprint are closely related to the social and economic development. Therefore, the industrial structure should be fully adjusted, and the water resources should be scheduled and utilized reasonably so as to pro- mote the protection of water resources and sustainable development of society and economic in Jiangxi Province.