摘要
野外勘察和大量物理力学性质试验结果表明,古尔班通古特沙漠砂的厚度一般小于200m。粒径较均匀,控制粒径(d60)变化范围在0.12～0.25之间,由北至南,从上到下砂粒直径略有减小。在天然状态下,沙漠砂含水量1%～2%,干密度1.55～1.62g·cm-3,中密状态,低压缩性,渗透系数2.0×10-2～4.0×10-3cm·s-1,临界破坏比降0.9～1.7,破坏形式为流土。抗剪强度指标c=5.0～14.0kPa,φ=29°～34°。承载力特征值100kPa。天然状态的沙漠砂按冻胀率划分为不冻胀性砂,当含水量小于18%时,为不冻胀或弱冻胀性砂。当砂在饱和状态时为冻胀性砂。沙漠砂力学性质的变化主要受干密度和含水量的影响。干密度越大,含水量越小,其力学性质越好。对于沙漠工程,提高沙漠砂的干密度,做好构筑物的防渗排水,避免地基含水量增高,是保证工程设施安全、正常运行的关键。
The field survey and a great deal of experimental studies for physical and mechanical characters indicate that the sand thickness of Gurbantonggut desert generally is less than 200 m,sand grains are uniform and their dominant diameter(d_(60))vary between 0.12 and 0.25,the grain size is decreased toward the south and from surface to deep. In natural environment, the moisture of dune sands is 1%～2%, the drysand density is 1.55～1.62 g·cm^(-3),it belongs to middle density and low compressibility. The infiltration coefficient is 2.0×10^(-2)～4.0×10^(-3 )cm·s^(-1),the critical breakage ratio is 0.9～1.7 in earth flow form. The shearing strength is indexed as c =5.0～14.0 kPa and φ=29°～34°. The characterized bearing capacity is 100 kPa. Based on the degree of frost heaving, dune sands can be classified as no-frost heaving sands in natural environment, no or weak frost heaving sands in less than 18% of moisture, and frost heaving sands in water saturated condition. The mechanics of dune sands is affected by dry density and moisture. The higher the dry density is, the less the moisture is, and the better its mechanics is. For engineering in desert, the key measures for ensuring the safety and operation of engineering facilities are to increase dry density and enhance seepage so as to avoid the high moisture content.
出处
《中国沙漠》
CSCD
北大核心
2005年第4期563-569,共7页
Journal of Desert Research
