砂泥岩互层边坡膨胀性泥岩力学性能试验研究

泥岩和砂岩互层边坡中的泥岩吸水时将受到泥岩膨胀致其应力σ增加和抗剪强度参数（c，φ）降低双重作用影响。随着含水率的增加，σ增大，c，φ值减小，τ的变化情况及这一规律的含水率阈值的确定是要着重解决的问题。基于室内有侧限膨胀试验及直剪试验，研究了十八里堡水库段泥岩膨胀率与上部荷载、时间、初始含水率及自然膨胀力关系，以及黏聚力和内摩擦角与含水率的关系，据此推导出了以吸水率（含水率变化）为自变量的泥岩抗剪强度公式。研究结果表明:该处泥岩含水率阈值为13.5%，在含水率阈值以内抗剪强度随着含水率的增加而增大；当含水率继续增大，超过含水率阈值，则抗剪强度随着含水率的增加而减小。

Research on Mechanical Behavior of Expansive Mudstone of Sand Shale Interbed Slope

The water absorption of mudstone on mudstone and sandstone interbedded slope will be influenced by the increase in internal stress(σ) induced by mudstone swelling and the reduction of shear strength parameter cohesion force and internal friction angle(c,φ). With the increase of water content, σ will be increased and c and φ will be reduced, the changes and the determination of the water content threshold under this rule are the main problems to be solved. Based on the laboratorial lateral restricted swelling and direct shear tests, the relationships between swelling ratio of mudstone and upper load, time, initial water content, natural swelling force, and the relationships between cohesion, internal friction angle and water content were studied for the section of Reservoir Shibalibao. Then the shear strength formula was deduced on the basis of water absorption ratio(water content variation)as independent variable. The results show that the water content threshold of the mudstone is 13.5 %, and the shear strength increases with the increase of water content. If the water content continuously increases to exceed the threshold of water content, the shear strength decreases with the increase of water content.