关键词: 桂林红土, 物质组成, 物理力学性质, 工程地质问题

Abstract: Depending on the field investigation, the tested results of soil samples and the previous data, the engineering geological characteristics of Guilin laterite were studied systematically. The minerals of the laterite mainly include Quartz sand and clay minerals (with a content of 40%~75%) such as kaolinite, illite and chlorite, and a few montmorillonite and vermiculite, etc. In the laterite, iron and aluminum oxides are rich with the content of Al₂O₃=15.3%~25.9% and Fe₂O₃=6.4%~11.2%, and the content of clay grain is usually more than 50%; the water content, the liquid limit, the void ratio and the saturability are high, i.e., w=26%~40%,w_L=42%~70%,e=0.8~1.1,S_r=90%~100%; the shearing strength is large(c=40~85 kPa,Φ=15°~30°);the compressibility and the permeability coefficients are small with the value of 0.3 MPa^-1 and 1.5×10^-6~5.0×10^-8 cm/s respectively. There are many engineering geological problems of Guilin laterite,such as a great quantity of earth caves in the laterite, a lot of soft soil developed in lapie of carbonate rock surface and that the thickness of soil layer varied within a little range. The collapse of land surface were often taken place by the earth caves and the soft soil. All engineering characteristics of Guilin laterite were completely depended on the forming environment of the laterite.

Key words: Guilin laterite, material compositions, engineering geological properties, engineering geological problems