山区道路边坡碎裂砂岩不同含水状态下强度劣化机理试验研究

Experimental Study on Strength Mechanism of Fragmented Sandstone of Mountain Road Slope under Different Water Conditions

本文针对山区道路路基碎裂岩边坡稳定性问题,为研究坡体碎裂岩饱水后强度劣化特性,依托某城市道路工程K2+260~K2+360路基右侧高边坡工程,采用超声波回弹综合法进行碎裂砂岩现场选样,应用电液三轴伺服试验系统,分别开展碎裂砂岩岩样在自然状态及吸水饱和状态下的变形及力学特性试验研究。试验结果表明:岩样饱水后的单轴抗压强度和弹性模量分别下降了31.12%和28.98%,说明其属水敏性岩石;岩样应力-应变全过程曲线均出现多个峰值点及多次应力下降,曲线产生突跳,说明岩样节理裂隙发育导致结构不均匀。开挖卸荷过程中如果防护不及时,坡体内应力可能会沿某个软弱面集中形成优势面,从而导致坡体失稳。

This study on right side roadbed slope project relies on K2+260~K2+240 of a roadproject in mountain areas.Research focus on cataclastic rock slope stability of road rehabilitation and expansion project and strength degradation of saturated cataclastic rock.With siltstone sampling by ultrasonic-rebound combined method,mechanical and deformation behavior of natural samples and saturated samples were tested by the dynamic tri-axial instrument of MTS815.04.Results shows that compressive strength and elastic module of saturated samples decreased 31.12%and 28.98%separately,for which is watersensitive rock,and stress-strain curve has several peaks and stress decreases,as that joint fissures develop.If slope is not protected appropriately,weak layer will become preferred plane in the action of regional stressing,as slope collapses.