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天山公路典型溜砂坡防治措施研究 总被引:2,自引:1,他引:1
溜砂坡是我国西部山区公路的主要地质灾害之一。由于对溜砂坡的形成发展机理认识不足,目前采用的治理措施不能很好地解决溜砂灾害,有些工程措施反而会加大灾害程度。通过对天山公路沿线溜砂坡的调查研究,以K612+750~K613+850段特大溜砂坡群为例,阐述该溜砂坡的最基本特性,分析溜砂坡的成灾机理和危害性特点,并对溜砂坡防治措施进行研究。 相似文献
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川藏公路中坝段溜砂坡形成与防治对策 总被引:13,自引:0,他引:13
溜砂坡是斜坡重力侵蚀的一种特殊类型,在特定的地形、地质和气候条件下形成和演化而成的。常对公路、铁路、渠道等线路工程构成严重危害。论文以川藏公路(318国道)西藏境内中坝段为例,从溜砂坡的基本特征、形成与分布规律研究入手,通过现场调查、测试和室内模型试验,研究溜砂坡的形成机理、运动力学特征与防治对策。建立了溜砂坡形成、发生、运动力学模型。提出了封闭砂源区、改变砂坡结构、公路内侧修建挡砂工程和坡面生态快速固砂的防治对策。 相似文献
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基于青藏高速公路某隧道出口溜砂坡的现场勘察、测试及室内试验,通过工程地质分析与相似模型试验,对该溜砂坡的发育特征、影响因素、形成机理进行了探讨,并提出了防治对策。结果表明:该溜砂坡为大型砂粒、碎屑牵引式中强活动溜砂坡;不同颗粒比重条件下溜砂坡的影响因素主要包括含水率、冻融、地震力、工程活动等方面,中砂的天然休止角小于粗砂、砾砂等粗颗粒,含水率与砂粒的天然休止角呈正相关,在含水率达到10%以后影响效果减弱,冻融作用对粗颗粒的休止角影响较大,当含水率达到一定条件后,冻融作用才开始凸显,当含水率增大到一定程度时,冻融对休止角的影响呈减弱趋势,地震力作用在低含水率条件下,作用显著,随着含水率的增加,效果减弱;将溜砂坡划分出了砂源区、溜动区、堆积区三个分区,从力学、运动学角度分析了该溜砂坡的形成、运动与复活全过程;提出了砂源区控制+固砂+排砂综合防护对策。 相似文献
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溜砂坡具有突发、不易预测,且产生危害大的特点。文章对拉萨市周边实地调研测量收集数据,采集了12组具有代表性的溜砂坡灾害点数据集合,运用贝叶斯网络与粒子群算法相结合,并利用算法更新公式弥补单一算法的不足,引入信息熵分析了降雨量、坡度、坡高和植被覆盖率在算法中的权重,以及各因素对溜砂坡稳定性的影响,并对溜砂坡的稳定性进行了等级划分,实验证明该方法有效,对溜砂坡稳定性评价具有一定参考价值。 相似文献
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天山公路溜砂坡防治工程参数试验研究 总被引:1,自引:1,他引:1
天山公路北段地处北天山褶皱冲断区,构造运动强烈,物理风化十分严重.溜砂坡广泛分布于公路沿线,严重影响天山公路的畅通和安全.本文针对溜砂坡防治工程进行了室内物理模拟试验研究,并提出了具体的工程设计参数. 相似文献
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溜砂坡防治工程安全系数实验探索 总被引:4,自引:1,他引:4
采用干燥沙石散粒体临界单面坡沙堆坍滑实验,对颗粒均匀和较大非均匀度沙石建造的临界坡面的坍滑动力学特性进行了探索.颗粒均匀的沙堆坡面出现准周期、大规模的沙石“雪崩”,坍滑重量符合统计的正态分布。而非均匀度较大沙堆的坍滑规模呈现多样化的负幂率分布。从理论上探讨了这2种动力学特性对坍滑的概率风险度以及防治工程可靠度的影响关系。结合实验结果分析认为,当坍滑灾害发生概率α减小情况下,颗粒非均匀溜砂坡的防护工程所需考虑的外荷载安全系数迅速增大,并将逐渐大于颗粒均匀的溜砂坡。尤其在α较小,即对工程可靠度要求较高的情况下,安全系数的增大更为显著。 相似文献
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《Geomechanics and Geoengineering》2013,8(1):41-49
Laboratory investigations such as resonant column, cyclic triaxial, and torsional shear tests are usually conducted on undisturbed and reconstituted sand samples in order to determine their shear modulus, which can be used to compute shear wave velocity. However, these methods are extremely cumbersome and indirect, they employ cost-intensive instrumentation, and they require trained manpower. These problems can be overcome by using bender elements, which yield the shear wave velocity of sands directly, easily, and quite rapidly. In this context, efforts made by earlier researchers in developing empirical relationships (based on bender elements and resonant column techniques) which can be employed to compute shear wave velocity in sands are worth consideration. Although these relationships take into account parameters like effective stress and void ratio, they do not directly incorporate fundamental characteristics of sands such as their state (i.e. dry or saturated) and the particle size. Thus a generalized relationship, which can be used to compute shear wave velocity in sands in either the dry or saturated state, has been developed. Experiments were conducted on samples of sand and glass beads of different sizes and the results were used to demonstrate the utility and efficiency of the relationship. Details of the methodology developed for this purpose are also presented in this paper. 相似文献
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The sedimentation rate of sand grains in the hindered settling regime has been considered to assess particle shape effects. The behaviour of various particulate systems involving sand has been compared with the widely used Richardson–Zaki expression. The general form of the expression is found to hold, in as much as remaining as a suitable means to describe the hindered settling of irregular particles. The sedimentation exponent n in the Richardson–Zaki expression is found to be significantly larger for natural sand grains than for regular particles. The hindered settling effect is therefore greater, leading to lower concentration gradients than expected. The effect becomes more pronounced with increasing particle irregularity. At concentrations around 0·4, the hindered settling velocity of fine and medium natural sands reduces to about 70% of the value predicted using existing empirical expressions for n. Using appropriate expressions for the fluidization velocity and the clear water settling velocity, a simple method is discussed to evaluate the sedimentation exponent and to determine the hindered settling effect for sands of various shapes. 相似文献
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溜砂坡滑塌特性及内在演化结构实验探索 总被引:1,自引:0,他引:1
溜砂坡滑塌特性与内在演化结构的认识,有助于对该高寒地区山地道路灾害的防治与预报。通过非连续与连续加沙两种形式的干燥沙石散粒体临界态单面坡室内模型实验,初步探索了溜砂坡的滑塌规模统计特性与演化动力学规律。发现其受颗粒级配非均匀度影响而异差异很大。非均匀沙堆呈现明显负幂率分布统计特点。对滑塌演化动力学的相空间分析进一步揭示,非均匀沙堆的演化结构复杂,动力学吸引子分维数较大;而均匀沙堆演化结构相对简单,体现准周期特点,可以自相关分析进行主周期预测。利用小波变换,分析了非均匀沙坡滑塌演化的复杂内在结构,即演化过程由不同周期、不同规模的滑塌一回复过程复合而成。尝试以选择合适预报精度进行时间尺度变化,用小波系数截线对演化活跃周期初步估计。 相似文献
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