冰碛土作高土石坝防渗体材料的试验研究

The Study of Glacial till used as Core Meterial for High Rock-Earth Dam

本文对四川瀑布沟水电站黑马料场的冰碛土进行了试验。首先分析了冰碛土的矿物组成、微观结构、物理性质和渗透变形,然后对这种宽级配的粗颗粒冰碛土作为高土石坝防渗体作出评价.其次,指出这种高密度的冰碛土的应力应变特性属于非线性弹、塑性性质。在50～3500KN/m^2压力范围内其破坏包线近似于直线。当围压增加,在低压下,呈应变软化且体积剪胀:在高压下,呈应变硬化且体积剪缩。确定出冰碛土供土石坝进行有限元计算的非线性变形参数,并对 E～μ及 K～G 两种模型之间系统地进行比较研究。结果表明,成都科技大学建议的简化 K-G 模型比其它模型更为适用于冰碛土。因此,它可用作为实际工程的模型.

Glacial till,Which was from the Heama material Storage of Pubugo Po- wer Station in Schichuam province,has been tested.In this paper,We first analyzed the seepage deformation of the till,and then evaluated the possibility that such broadly graded coarse soll as till was used as antl-seepage material for high rock-earth dam. Next,it was indicated that the stress-strain characteristics of the high density till were nonlinear elasto-plastic.The failure envelope line was appro- ximately linear in the pressure range of 50～3500KN/m^2.With incraesing of confining pressure,the strain-softenlng and volumetric dilatation at low pres- sures changed into the strian-hardening and the volumetric contraction at high pressures.The non-linear deformation parameters of the till for finite ele- ment calculation of rock-earth dam could be determined.According on the studles,the simplcid K-G model suggetted by Chengdu Uuiversity of Scien- ce & Technology,showed more suitable for this till than other models.The- refore it was a useful model for practical engineering.