塔克拉玛干沙漠腹地风沙土的力学性质

风沙土是形成于干旱、半干旱区的一种特殊性质的土,其力学性质不同于一般土体,结构松散性为其最主要的特点。通过对塔克拉玛干沙漠腹地14个风沙土样进行压缩试验和抗剪试验,获得了风沙土的基本力学参数:风沙土压缩模量值在50.00~142.86MPa之间,是一种低压缩性土;风沙土的内摩擦角值在31°55'~36°19'之间,低于河流冲积砂的内摩擦角值;风沙土存在结构力,其力学效应相当于粘聚力,可以在剪切试验中测出,其值在0.6~9.3kPa之间。并分析了影响这些力学参数的主要因素。

Mechanical Properties ofAeolian Sandy Soil in Central Taklimakan Desert

Aeolian sandy soil is a kind of peculiar property soil, which was formed in arid or semiarid area. Very loose structure and mobility characterize this kind of soil. This paper presents the results of an extensive laboratory-testing program carried out to determine the mechanical properties of aeolian sandy soil taken from three sites in Tazhong. The tests included on compressibility and shear strength. The results are presented and discussed as a first step toward a better utilization or improvement of this kind of soil for local construction purposes. From the results of tests on 14 samples the following conclusions are reached:　　(1) The compressibility modulus (Es) of aeolian sandy soil varies between 50.00 MPa and 142.86 MPa, the compressibility coefficient varies between 0.01 MPa -1 and 0.04 MPa-1. With a very small compression coefficient of less then 0.1 MPa -1, aeolian sandy soil belongs to a kind of low compressibility soil. This means this kind of soil is highly incompressible when compacted. The disparity of compressibility modulus are very small in three different geomorphic units, the average Es of lee slope of barchan is 92.36 MPa, the average Es of stoss slope of barchan is 97.52 MPa, and the average Es of interdune is 78.085 MPa. The main influence factors to the compressibility are the grain size distribution, mineral component, shape of grain and the initial void ratio.　　(2) The angle of internal friction of aeolian sandy soil varies between 31°55′and 36°19′that lower than alluvial sand. The internal friction angle of three different geomorphic unit samples have very small difference, the average value of lee slope of barchan is 33°42′, stoss slope is 34°12′and the interdune is 32°30′. The main influence factors to the internal friction angle are the grain size distribution, density and roundness. The theoretic cohesive force of aeolian sandy soil is zero. But the shear strength tests could detect cohesive force, the value are in the range of 0.6 kPa to 9.3 kPa. We are deeming that the value C is a kind of structure force. The vale C has good correlation with sorting coefficient, the correlation equation is C=9.7955-3.5622 SOS and the correlation coefficient is -0.85. So the main influence factor of the structure force is grain size distribution.