黏土抗渗强度试验研究——以桂林铁山工业园工程场地红黏土为例

Experimental Study on Testing the Anti-permeability Strength of Clay Seepage Failure: A Case from the Engineering Field of Tieshan Industrial Park in Guilin,China

土的渗透变形是很多地质灾害及岩土工程事故的主要原因之一,但目前黏土的渗透破坏临界条件研究较少。从微观角度分析了黏土在外界驱动水压作用下的渗透破坏过程,以抗渗强度作为黏土渗透破坏临界条件参数。为获取此参数,设计了模拟外界驱动水压作用下,黏土渗透破坏过程的抗渗强度试验装置及方法。选取广西桂林红黏土层底部原状样,测试了32组不同厚度试样,并得出各试样抗渗强度。依据试验结果,分析了抗渗强度受渗透方式和尺寸效应的影响,并采用Arc Gis软件统计分析试样抗渗强度的差异性。最终选择15组实际渗透厚度2.5 cm试样的试验结果平均值40.8 k Pa,为工程场地黏土抗渗强度值。通过比较抗渗强度值与钻孔实际监测渗透水压,评价工程场地内黏土渗透破坏形成土洞塌陷的可能性。评价结果表明,目前工程场地内黏土渗透驱动水压低于抗渗强度,不具备形成土洞的条件。经实地勘察,评价结果符合现场实际情况。

A lot of geological hazards and geotechnical engineering failure cases including slope, dam, construct foundation, et al, are caused by soil seepage deformation. However, it is seldom to study the critical condition of clay seepage failure. This paper represents the microprocess of clay failure caused by additional driving pres- sure, and takes the anti-permeability strength as the critical condition for judging clay seepage failure. Firstly, the equipment and method which stimulate the process of clay failure were designed to test the strength. Second- ly, 32 undisturbed samples of clay were tested with different thickness, which are from the engineering field of Tieshan industrial park in Guilin, China. With the testing values of 32 samples, it is concluded that the two factors of seepage ways and sample size influence the anti-permeability strength, and the test results are made by statistical analysis of ArcGis. The average value of 15 samples of 2.5 cm thicknesses, 40. 8 kPa, is the anti- permeability strength of the engineering field. Finally.by comparing the strength with the seepage water pres-sure in field, the probability of clay seepage failure to form there is a low susceptibility to the formation of subsidence water pressure is less than the anti-permeability strength in suh is consistent with the truth. soil-cave collapse is assessed. Results indicate that sinkholes under current conditions, as the seepage field. By the field investigation, the assessment re-suh is consistent with the truth.