胶凝砂砾石坝模型试验突变理论破坏判据

地质力学模型试验是研究胶凝砂砾石坝（cemented sand-gravel dam，CSG坝）安全稳定性的一种研究方法，但在试验中，模型的变位位移比较微小、倾覆趋势不易捕捉，并不能精确地判断出试验中模型受压破坏的区间及其超载安全系数（模型破坏时的极限安全系数）。针对这一问题，本文通过开展CSG坝复杂地基条件下地质力学模型试验，得到了坝基内部应变、坝体下游面位移及坝体表面应变等数据，判断出模型的超载安全系数Kp在4.6 ~ 6.2区间内；为得到模型精确的超载安全系数，首先运用突变理论对模型试验数据进行四次多项式拟合，后将结果代入模型失稳判别式，得到了模型的超载安全系数Kp的精确区间为6.0 ~ 6.2。本文解决了困扰CSG坝地质力学模型试验中超载安全系数精确性的问题，对CSG坝后续的推广、发展和应用起到了积极的作用。

Study on failure criterion of cemented sand-gravel dam model test based on catastrophe theory

Geomechanical model testing is a key approach to studying the safety and stability of a cemented sand-gravel (CSG) dam. However, displacements of a tested model dam are relatively small and the overturning trend of the dam is usually difficult to capture, so its compression failure interval and overload safety factor (or ultimate safety factor in failure stage) cannot be determined with enough accuracy. To overcome this problem, we conduct geomechanical tests on a model CSG dam, and measure strains in the dam foundation and at the dam surfaces and surface displacements at the downstream dam face. The overload safety factor Kp of the model dam are estimated in the range of 4.6 ~ 6.2. To determine this factor accurately, first we use the catastrophe theory to fit a quadratic polynomial to the model test data, and then the fitted values and instability discriminant are used to finalize its values－an accurate Kp range of 6.0 ~ 6.2. This method solves the accuracy problem in calculation of the overload safety factor of a geomechanical model CSG dam, and helps promote its development and application.