砂砾软岩的极限承载力分析

利用Hoek-Brown强度准则建立砂砾软岩极限承载力分析方法,提出岩基剪切破坏模型,推求潜在破坏面上正应力计算公式。结合某工程现场载荷试验探讨砂砾软岩的极限承载能力及自重应力对极限承载能力的影响。研究结果表明:极限承载力的计算结果大于预估设计荷载,砂砾软岩在强度方面尚有很大潜力可挖;同时,极限承载力的计算结果弥补了现场载荷试验中由于试验条件所限造成的荷载–变形曲线上峰值荷载不能给出的缺陷,为建立完整的变形曲线模型奠定了理论基础。研究成果为研究砂砾岩一类软岩的承载力提供了新的途径。

STUDY ON ULTIMATE BEARING CAPACITY OF SOFT SANDY GRAVEL ROCK FOUNDATION

The method to calculate the ultimate bearing capacity of soft sandy gravel rock foundation is established based on Hoek-Brown strength criterion. In order to study its ultimate bearing capacity,the shear failure model is suggested;and the formulas for calculation normal stress levels on potential failure surface are ascertained. Combined with in-situ loading test of a certain hydraulic project,the bearing capacity of soft sandy gravel rock foundation and the effect of dead load stress on the bearing capacity are discussed. The calculation results show:(1) the method covers shortage which is difficult to obtain peak value of load at load-settlement curve due to the field test condition;(2) the calculation ultimate bearing capacity is greater than design intending load,which indicate that the strength of soft sandy gravel rock can satisfy the demand of the project;(3) the rational design footing load has a minor effect on ultimate bearing capacity,which is very important for obtaining normal stress on potential failure surface;(4) the dead load stress has apparent effect on ultimate bearing capacity;and (5) the difference between solutions of Hoek-Brown and Bell on ultimate bearing capacity is comparatively small. The analysis results provide new reference to the study of bearing capacity of this type in soft sandy gravel rock foundation.