RESEARCH ON DEFORMATION AND STRENGTH CHARACTERISTICS OF SANDS AND SOFT ROCK GROUND UNDER HIGH PRESSURE CIRCUMSTANCE.

通过一系列的试验和分析研究，探讨了应力状态、砂粒的主要性质、砂粒的物理力学性质等影响因素对砂粒和软岩变形强度行为的影响。对于砂，制备了200种不同初级性能的砂样。研究了颗粒密度、形状和粒度分布等指标性能之间的关系，证明了最大、最小孔隙比、可破碎性等指标性能表征了砂粒的物理性质。阐明了主要性能对砂土变形强度特性的显著影响，从试验结果出发，讨论了砂土的变形强度性能与指标物理性能之间的关系；晶粒形状、级配和可破碎性对其力学性能有显著影响。为了进一步研究软岩的强度-变形特征，在水平冲力作用下岩层褶皱的坝址进行了水平方向和垂直方向的取样。在渗透率、破坏和残余三轴强度以及屈服围压的各向异性特征方面获得了有趣的信息。指出应力历史对软岩力学行为的显著影响。通过对人造软岩地基上圆形地基模型进行一系列加载试验，研究了软岩地基的变形破坏机理。考察了地基几何形状、地基尺寸、地基材料力学性能和地基相对于边坡顶部位置与破坏模式类型的关系；一般剪切模式或大变形带冲孔破坏模式。提出了改进的切片法，并将其应用于圆形边坡基础极限承载力的计算中。二维计算给出了不可接受的欠估计，而三维计算给出了地基材料、坡角、基础与边坡附近的变化的合理估计。少

A series of experimental and analytical examinations was carried out to investigate the effects of several influencing factors, such as stress state, primary properties of sand particles, physical and mechanical properties of sands, on the deformation-strength behavior of sands and soft rocks.For sands, 200 kind of sand samples with different primary properties were prepared.The relationships between the index properties, such as grain density, shape and size distribution were investigated, It was proven, that some index properties such as maximum and minimum void ratio, crushability characterize physical property of sands.The significant influence of the primary properties on the deformation-strength characteristics was also clarified, From the test results, the relationships of deformation-strength properties of sands with index physical properties are discussed ; the significant influence of grain shape, grading and crushability on the mechanical behaviors are presented.To investiga … More te the strength-deformation characteristics of soft rock, samples from horizontal and vertical directions were secured from the dam construction site, where strata were folded by horizontal thrust. Interesting information on the anisotropic characteristics of permeability, failure and residual triaxial strength, and yielding confining pressure were obtained. Significant effects of stress history on the mechanical behavior of soft rock, were pointed out.Deformation and failure mechanism of soft rock ground were investigated by several series of loading tests on model circular footing on artificial soft rock grounds. The effects of geometry of ground, footing size, mechanical properties of ground materials and relative position of footing from the top of slope were examined in connection with the type of failure mode ; general shear mode or large deformation with punching failure mode.Modified slice method was proposed and applied to the calculation of the ultimate bearing capacity of circular footing beside slope. While 2-dimentional calculation gave unacceptable under estimate, 3-dimentional calculation gave the reasonable estimate for the variation of ground material, slope angle, and the vicinity of the footing to the slope. Less