共查询到20条相似文献，搜索用时 93 毫秒
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深基坑护坡桩施工采用钻孔压灌超流态砼成桩法、大头锚杆、旋喷防渗墙、深基坑降水是解决目前深基坑施工难点的重要方法。钻孔压灌超流态砼成桩法：采用优化的结构和简便实用的施工方法，克服了原有复杂的钻孔护壁工艺，使用砼搅拌机、砼泵，压灌超流态砼钻机，连成一条龙半机械化工艺流程，可在桩孔内超流态砼中下钢筋笼，一次成桩新工艺，砼强度在Ｃ２８以上，承载力是普通灌注桩的１．３￣１．９倍，适合各种复杂地质条件下施工， 相似文献
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本文从理论分析入手结合施工实践研究特细砂的数量，单位用水量及单位水泥用量对配制高流动度砼的影响，寻求砂率值的合理范围，获得了既能保证达到设计强度要求又能满足施工需要的坝落度这样一种特细砂砼配合比，并提供了保证施工质量的工艺措施。 相似文献
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碳化是砼工程中影响砼结构耐久性的主要因素之一。对冯家山灌区郭家庄渡槽的碳化运用随机模型理论进行数值分析,发现渡槽的碳化深度与砼强度关系密切,最终运用最小二乘法对所得数据进行了线性拟合,得到了郭家庄渡槽槽身、钢筋砼排架和墩台碳化寿命预测,并对郭家庄渡槽按期进行了针对性加固,效果良好。 相似文献
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水下砼灌注施工过程的系统质量控制福建省福州福新基础工程公司鲍忠厚钻孔灌注桩水下砼灌注施工全过程是形成工程实体的阶段，也是形成最终产品质量的重要、关键阶段。所以，施工中进行严格的工序监控，才有可能保证桩身的设计强度，避免在水下边灌注的过程中发生质量事故... 相似文献
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目前国内的220kV及以下等级输电线路铁塔大部分采用阶梯式砼基础。这种基础的挖土量大，砼灌注量大，施工速度慢，同时破坏了周围原状土的强度。经与输电线路设计人员研究、比较后认为，220kV及以下等级输电线路铁塔基础应采用钻孔桩基础（这在超高压输电线路及跨江塔中已应用）。经计算，钻孔桩基础的砼灌注量只有阶梯式基础的1/3。为此我们决定进行实际施工试验。 相似文献
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井壁破裂与砼的徐变破坏 总被引：1，自引：1，他引：0
黄淮地区煤矿井壁破裂大都是由于厚松散覆盖层底部含水层失水固结,地层沉降,导致井壁外侧出现负摩阻力,从而在竖井轴向上形成附加的下拉荷载而引起。这些破裂始见于保护层砼的剥落,而后见壁中砼发育密集的竖直砂浆裂隙,砼中骨料因界面裂隙的发育而被剥离,砼向井内膨胀并呈现“假塑性”等。除这些特征外,从负摩阻力的出现及增荷过程来看,井壁破裂是在轴向高压应力长时间作用下的结果,它涉及的是井壁砼的长期强度,故井壁破裂属于砼徐变破坏。 相似文献
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Demolition of old buildings to create space for new development resulted in the near surface soil (topsoil) to be mixed with particles derived mostly from concrete wastes. This condition could affect the infiltration capacity and surface runoff, therefore, storm-water management of the area. This paper presents results of study on the effect of concrete waste particles on the hydraulic properties and infiltration capacity of the topsoil. Laboratory tests were performed to compare the hydraulic properties of the topsoil and the mixture of topsoil and concrete particles. Laboratory infiltration column test was performed on the mixture to evaluate its infiltration capacity. Results from the laboratory tests indicated that the presence of particles from concrete waste decreased the water-holding capacity and permeability, thereby the infiltration capacity of the ground surface. The results were supported by numerical analysis performed using the same material and boundary conditions as the column test. Parametric study was performed on both the topsoil and the mixture to extend the results of infiltration test to different materials under different ranges of rainfall intensity. The parametric study showed that the presence of concrete particles increased the run-off and the effect increased as the rainfall intensity increased. Therefore, the increase in runoff coefficient should be considered for the storm-water management when the near surface soil is mixed with concrete waste. 相似文献
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以北京昌平未来科技城试验基地的降雨强度为降雨条件，通过室内降雨试验平台，研究了4种典型不透水下垫面（沥青、砼面、SBS改性沥青和砼方砖）和4种典型透水下垫面（草坪砖A、草坪砖B、风积砂砖A和风积砂砖B）分别在8种恒定雨强条件下形成薄层产流后的糙率系数、沿程阻力系数和径流系数的变化过程。结果显示：平面尺寸、表面光滑度、材质对不透水下垫面的糙率和沿程阻力系数影响较为明显；而结构、材质对透水下垫面的糙率和沿程阻力系数影响较为明显；两类下垫面的糙率值和沿程阻力系数均随雨强增加呈现减小的变化趋势，但变化的幅度较小，之后逐渐趋于稳定；两类下垫面的径流系数在不同雨强下保持相对稳定。 相似文献
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以北京昌平未来科技城试验基地的降雨强度为降雨条件，通过室内降雨试验平台，研究了4种典型不透水下垫面（沥青、砼面、SBS改性沥青和砼方砖）和4种典型透水下垫面（草坪砖A、草坪砖B、风积砂砖A和风积砂砖B）分别在8种恒定雨强条件下形成薄层产流后的糙率系数、沿程阻力系数和径流系数的变化过程。结果显示:平面尺寸、表面光滑度、材质对不透水下垫面的糙率和沿程阻力系数影响较为明显；而结构、材质对透水下垫面的糙率和沿程阻力系数影响较为明显；两类下垫面的糙率值和沿程阻力系数均随雨强增加呈现减小的变化趋势，但变化的幅度较小，之后逐渐趋于稳定；两类下垫面的径流系数在不同雨强下保持相对稳定。 相似文献
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本文根据弹性波理论,采用数理统计的方法,简要介绍了弹性波法在混凝土预制桩出厂前无损检测中的应用方法,同时对桩身混凝土纵波速度与混凝土强度的关系进行了实验分析,并对桩身缺陷位置及性质的判定方法进行了简要介绍。 相似文献
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混凝土体内钢筋位置检测实例：高频地质雷达应用效果 总被引：4，自引：0，他引：4
通过高频雷达对混凝土体内钢筋位置检测的实例,展示其作为一种地下不明障碍物进行无损检测或评价地下工程质量的高新技术,具有良好的应用效果。 相似文献
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泡沫混凝土隧道减震层减震机制 总被引：2，自引：0，他引：2
基于泡沫混凝土隧道减震材料,通过室内试验研究了不同密度、围压、应变率条件下泡沫混凝土材料的力学特性。试验结果表明：随着密度的增加,试样的单轴破坏形态由骨架坍塌破坏逐渐转化为劈裂剪切破坏,峰后应变软化与材料脆性增强;随着围压的增加,材料强度增加且延性增强,峰后由应变软化逐渐转换为应变硬化。在中等应变率范围内（10?5/s ～10?3/s）,随着应变率的增加,泡沫混凝土材料的强度近似呈指数增长,同时峰后残余应力增长明显,且塑性应变越大,应变率对峰后应力的影响越大。基于上述试验结果初步建立了泡沫混凝土材料的本构模型。依托嘎隆拉隧道,采用数值方法研究了减震层剪切模量、厚度及减震层-衬砌界面特性3个因素对减震效果的影响规律,相关研究成果可为高烈度区隧道工程减震层的设计提供参考。 相似文献
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以平面有限元位移法对铁山隧道和大垭口隧道带裂纹二次支护内设钢筋混凝土衬套的补强效果进行了数值模拟。模拟结果表明：加了钢筋混凝土衬套后,可大大降低裂纹尖端的应力强度因子,显著地提高衬砌承载安全系数。 相似文献
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Empirical, theoretical or hybrid methods can be used for the vulnerability analysis of structures to evaluate the seismic
damage data and to obtain probability damage matrices. The information on observed structural damage after earthquakes has
critical importance to drive empirical vulnerability methods. The purpose of this paper is to evaluate the damage distributions
based on the data observed in Erzincan-1992, Dinar-1995 and Kocaeli-1999 earthquakes in Turkey utilizing two probability models—Modified
Binomial Distribution (MBiD) and Modified Beta Distribution (MBeD). Based on these analyses, it was possible (a) to compare
the advantages and limitations of the two probability models with respect to their capabilities in modelling the observed
damage distributions; (b) to evaluate the damage assessment for reinforced concrete and masonry buildings in Turkey based
on these models; (c) to model the damage distribution of different sub-groups such as buildings with different number of storeys
or soil conditions according to the both models. The results indicate that (a) MBeD is more suitable than the MBiD to model
the observed damage data for both reinforced concrete and masonry buildings in Turkey; (b) the sub-groups with lower number
of stories are located in the lower intensity levels, while the sub-groups with higher number of stories depending on local
site condition are concentrated in the higher intensity levels, thus site conditions should also be considered in the assessment
of the intensity levels; (c) the detailed local models decrease the uncertainties of loss estimation since the damage distribution
of sub-groups can be more accurately modelled compared to the general damage distribution models. 相似文献
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A theoretical model is proposed to describe the evolution of damage in brittle materials, such as concrete and masonry, subjected to increasing or sustained stresses of relatively high intensity. The model is based on the introduction of suitable damage variables in a rheological model. In this way, it is possible to describe the material behaviour under stresses either increasing or constant in time. The capabilities of the model in describing the mechanical response of material elements subjected to different stress histories are illustrated. Some correlations with experimental data from tests performed on masonry and concrete specimens are presented, to assess the reliability of the theoretical predictions. The results of some numerical applications to non‐proportional stress paths are also illustrated. Finally, the limitations of the proposal are discussed and possible further improvements are envisaged. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献