运用轻便触探和静载荷试验研究黄土的湿陷性(英文)

COLLAPSE CHARACTERISTIC OF LOESS UNDER STATIC LOADING AND DYNAMIC PENETROMETER TESTS

黄土在应力作用下迂水时力学强度迅速下降 ,产生大范围的快速沉陷。这就是黄土的湿陷性 ,是黄土的诸多特性之一。鉴于对黄土湿陷性以往用各种实验室试验指标进行评价 ,这里提出运用动力触探和静载荷试验进行黄土湿陷性原位评价的一种简便的新方法。该方法的试验程序是 ,先用轻便可变动能触探仪在天然状态和饱水状态下进行触探试验 ,而后在触探孔完成静载荷压缩性试验。运用中国黄土高原黄土原位动力触探和静载荷试验测得的资料 ,详细分析了天然状态的黄土对探头阻力 qdnat,饱水状态的黄土对探头阻力 qdsat,实验室测得的湿陷性指数δs压缩曲线参数 (即触探极限压力 ppf,触探蠕变压力ppl 和触探载荷模量Epn)的关系。结果证明所提出的方法适用于原位判定黄土的湿陷性。

Loess has various particular properties. One of them is its collapsibility when inundated with water. Collapse deformation occurs on a large scale, at a great speed. A rapid degradation of mechanical characteristics takes place when loess is wetted at constant stress.After a brief review of various criteria which were utilized for identifying collapse soils and are based on laboratory tests, a new simple methods were proposed to evaluate in situ loess collapsibility with help of dynamic penetrometer tests and static loading tests. The method consists in carrying out penetrometer tests with a portable dynamic penetrometer of variable energy in natural and saturated conditions as a first step, a compressibility test (static loading test) is then performed after the cone penetrometer tests.The paper presents the procedure of in situ penetrometer testing and static loading testing. With the data measured in Central Loess Plateau in China, a detailed analysis of correlation between loess cone resistance q dnat  in natural conditions, q dsat  in saturated conditions, the index of collapsibility δ s measured in laboratory and compressibility curve parameters (penetrometer limit pressure p pf , penetrometer creep pressure p pl  and penetrometer modulus E pn ) was taken. The results permit to state that the method proposed is suitable to characterize in situ loess collapsibility.