连云港地区绿片岩夹层力学性质试验研究

Experimental Study on Mechanical Properties of Greenschist Interlayer in Lianyungang Area

为了探究含水率和干湿循环变化对连云港地区软岩力学性质的影响,以该区发育的绿片岩为研究对象,在室内制备含水率分别为0%、10%、15%、20%、25%,以及干湿循环次数分别为1、3、5、7、9的绿片岩重塑样各4个,通过对每组试样进行法向压力分别为100、200、300、400 kPa的室内直接剪切试验,分析试样的内摩擦角、黏聚力以及抗压强度在不同状态下的变化规律.试验结果表明:从干燥到吸水过程中,试样的黏聚力和内摩擦角大幅降低,且随着含水率的增加,黏聚力及内摩擦角均表现为逐步降低.试样吸水后抗剪强度出现陡降且随着含水率的降低而降低.此外,试样的抗剪强度随着干湿循环次数升高而降低,但循环次数到达7次后,力学性质变化出现缓和.这对阐释暴雨工况下因绿片岩夹层出现遇水软化而导致边坡整体失稳的情况具有重要意义.

In order to explore the effect of moisture content and dry-wet cycles changes on the mechanical propertiesof soft rock in Lianyungang area,four remolding samples in each group with moisture content of 0%,10%,15%,20%,25% and wet-dry cycles of 1,3,5,7 and 9 respectively were prepared in laboratory for the greenschist developed in thisarea. Through the direct shear tests of under normal pressure 100,200,300 and 400 kPa for each group of specimens,thevariation rules of internal friction angle,cohesion and compressive strength of different states were analyzed. The resultshows that the cohesion and internal friction angle of these samples greatly reduced from the drying to water absorption,and the cohesion and internal friction angles gradually reduced as the water content increasing. The shear strengthof samples after water absorption dropped sharply and decreased with decrease of water content. In addition,theshear strength of samples decreased with the increase of dry and wet cycles,but the mechanical properties changedmoderately after the cycles reaching seven times. This interpretation is of great significance for the overall instability of theslope under rainstorm conditions due to the softening of the greenschist interlayer.