【作者】 金昌宁；

【导师】 李吉均；

【作者基本信息】 兰州大学 ， 自然地理学， 2006， 博士

【摘要】 自然条件极为恶劣的塔克拉玛干沙漠是流动性沙漠的典型代表。从其中部南北向贯通的塔克拉玛干沙漠公路则几乎穿越了所有的风沙地貌类型。 在国内外尚无先例的情况下,通过经验总结、技术引进、室内外试验及试验工程修筑等,在风积沙路基振动干压实、风积沙路基回弹模量、路基路面结构组合、土工布加固风积沙路基稳定性分析、沙漠公路施工工艺、沙漠公路沙害机械防治体系等方面取得重大突破的基础上,形成的成套的沙漠公路修筑技术,经实践证明具有技术可靠、经济合理、施工简捷等特点,由此建成的塔克拉玛干沙漠公路是世界上第一条长距离穿越流动性大沙漠的等级公路。 虽然上述研究成果已能为流动性沙漠地区修筑等级公路提供必要的技术支持,却仍还有不少问题没能很好地解决或值得进一步探讨与改进。这些问题虽有其局部性,却很有研究意义。这些问题的解决,不仅有利于更加全面地掌握风积沙的路用性能特征及其风沙运动规律,同时也有利于更为有效地降低沙漠公路造价及其养护成本。后一点则在沙漠地区显得尤为重要。因为沙漠地区经济发展滞后,公路交通量不大,一般情况下难以承受较高的公路建设与养护费用。 通过进一步研究,获得的认识主要有: <1>在防沙工程体系维护较为粗放的情况下,常会出现路基类型由低路堤转变为低路堑现象,后者的风沙危害频繁且又难以防治。因此,有必要适当地提高路基高度,提高45～80cm,平均60cm左右。 <2>在路线穿越高大的复合型沙垄时,垄体的上部与顶部一般会出现较长较深的挖方路段。在适当增加积沙平台宽度的条件下,该路段的路基边坡宜为落沙坡。 <3>在全国主要沙漠中,风积沙普遍具有较高强度,其路基回弹模量设计值多在90MPa以上,一般都大于现行有关规范中的砂性土或土质砂之指标。 <4>风积沙的压实度达90%以上时,浸水所造成的密度改变很小。则在适当增加试验次数等条件下,浸水+环刀法的试验结果是可以满足公路工程需要的。 <5>在一定条件下,栅栏拦截在足部的积沙量与风沙活动强度之间存在着较为明显的对应关系。据此,量测栅栏足部的积沙量,计算出在塔克拉玛干沙漠腹地的不同地貌类型及部位,风沙活动强度有所不同,输沙总量在3.25～更多还原

【Abstract】 The Taklamakan Desert is a represent of huge desert with migrating dunes, where the environmental conditions are extremely harsh. Through the center of the desert, the Taklamakan Desert Highway crosses various aeolian dune types from the north edge to the south.Because there is no precedent to build a desert highway all over the world, so we proposed series new techniques by generalizing the experiences, introducing the new technologies and testing the construction methods both in laboratory and field. In particular, considerable progress has been made on the dry compaction of aeolian sand by vibration, the resilience modulus of roadbed, the combination of different roadbeds and road surfaces, stability analysis of the geotextiles-strengthened roadbed, construction technologies of desert highway and the design of sand-controlling systems. The achievements of this research were successfully applied for the first time in the Taklamakan Desert. The results suggest that the construction of this highway was economical and that the simple construction methods produced a reliable highway. The resulting highway is believed to be the world’s first long-distance graded highway running through a huge desert with migrating dunes.The achievements provided some necessary supports on constructing the desert highway, however, some problems are still not well solved and need a further research. These problems are restricted in desert regions, but it’s very significant to solve these. To solve these problems, not only benefit to recognize the construction characteristics of aeolian sand and the law of sand drift, but also benefit to decrease the cost of constructing and maintaining the desert highway. In desert regions, the latter is especially important because that the poor-developed economy and the light road traffic make this region cannot bear the expensive cost.According to our research, some new progresses list below:<1> Under the rough maintenances of the engineering sand-controlling system, the roadbed type changed usually from low embankment to low cutting. The road cuttings are easily damaged by aeolian sand and very difficult to protect. So it’s very necessary to increase the height of the embankments about 45-80cm, with an average about 60cm.<2> There is a long and deep cut section where the highway across a high compound sand ridge. On these conditions, the slope of the roadbed should be the steepest slip face.<3> In most of the Chinese deserts, the strength of aeolian sands is very higher. The design values of resilience modulus of roadbed are above 90MPa and usually more than current standards of sand soil and soil sand.<4> The density changes very little after soaking when the compactness of aeolian sand is above 90%. By increasing the times of sampling, the density measured by soaking and ring sampler is properly to use in highway roadbed design.<5> Under given conditions, sand accumulate amount around windbreaks are obviously related to the activities of blown sand. According to this, the blown sand activities estimated by the sand deposits on different dunes and positions in the central Taklamakan Desert are distinguishing, and the sand transport amount ranged from 3.25 m3 ? m’1 ? a’1 to 17.04m3 ? m’1 ? a"1. At some interdune depressions, the lower longitude ridges may be the sand transport corridors.<6> On the compound longitude ridges, both the sand transport and the types of roadbed impact the sand hazards along the highway. The most serious disaster happens on the mid of stoss slope, and relieved in turn on the crest, upper stoss slope, upper lee slope and interdune depressions;the most light happens at the lower lee slope. The engineering methods to control blown sand can be improved based on our findings.<7> There are many reasons induce the overestimation of sand hazards in sand-controlling design, which include the disagreement of disaster intensity with sand transport rates, different efficiencies of shielding and conducting sands around windbreaks, disequilibrium of sand deposits within the sand-fixed belts, different sand transport abilities along highways and various standards in estimating sand hazards. To avoid these confusions, a clearly standard to estimate sand hazards should be established firstly. Secondly, we should mention that the blown sand activities in diflferent dune positions are various. In addition, the engineering measures have a huge sand capacity more than our estimated usually. Only thus, we could control the sand hazard and minimize the cost.更多还原